Group A Streptococcal Flesh Eaters

Streptococcus pyogenes was introduced in the chapters on skin and respiratory infections as the cause of strep throat, scarlet fever, and other conditions. It is also a common cause of wound infections, which have generally been easy to treat since the bacteria are consistently susceptible to penicillin. Occasionally, however, S. pyogenes infections can progress rapidly, even leading to death despite antimicrobial treatment. These more severe infections are called invasive and include...

A

310 Chapter 12 The Eukaryotic Members of the Microbial World 310 Chapter 12 The Eukaryotic Members of the Microbial World Figure 12.16 Examples of a Mycelium on Various Foods (a)The cottony white mass inside the potato is an example of a mycelium. (b) Magnified hyphae of Rhizopus stolonifer, black bread mold, showing the hyphae and the spores. Figure 12.16 Examples of a Mycelium on Various Foods (a)The cottony white mass inside the potato is an example of a mycelium. (b) Magnified hyphae of...

Surface Layers External to the Cell Wall

Bacteria may have one or more layers outside of the cell wall. The functions of some of these are well established, but that of others are unknown. Many bacteria envelop themselves with a gel-like layer called a glycocalyx that generally functions as a mechanism of either protection or attachment (figure 3.37). If the layer is distinct and gelatinous, it is called a capsule. If, instead, the layer is diffuse and irregular, it is called a slime layer. Colonies of bacteria that form either of...

Role Of Co2 As The Main Causative Agent

Consumed is employed to create biomass, however some is used as an energy source, generating carbon dioxide as a product. As plants lose their leaves, and members of the food web die, various decomposers degrade the resulting detritus, using it both as an energy source and to create biomass. The type of organic material helps dictate which species are involved in the degradation. For example, a wide variety of organisms utilize the more readily decomposable organic substances such as sugars,...

Prevention and Treatment

Because of the ubiquity of the causative organism, there are few effective preventive measures other than to avoid animal urine. Maintaining general sanitary conditions is helpful in the care of domestic animals raised for food. Multivalent vaccines, ones that contain a number of different serotypes of L. interrogans, are available for preventing the disease in domestic animals, but they do not consistently prevent the carrier state. In an epidemic situation, small doses of a tetracycline...

Epidemiology

Leptospira interrogans infects numerous species of wild and domestic animals, usually causing little or no apparent illness, but ranging to highly fatal epidemic disease. Characteristically, the organisms are excreted in their urine, which provides the principal mode of transmission to other hosts. Spots on the ground where urine has been deposited can remain infectious for as long as 2 weeks, while Leptospira in mud or water can survive for several weeks. Warm summer temperatures and neutral...

Csd

Figure 25.3 Leptospira interrogans, the Cause of Leptospirosis Note the hooked ends of this spirochete. Figure 25.3 Leptospira interrogans, the Cause of Leptospirosis Note the hooked ends of this spirochete. the site of entry, but the organisms multiply and spread throughout the body by way of the bloodstream, penetrating all tissues including the eyes and the brain. Severe pain is characteristic of this first (septicemic) phase, and it may lead to unnecessary surgery for suspected appendicitis...

Symptoms

A typical case begins after an incubation period averaging 10 days (range, 2 to 30 days), with abrupt onset of headache, spiking fever, chills, and severe muscle pain. The most characteristic feature of this phase of the disease is the development of redness of the eyes due to dilation of small blood vessels. In mild cases, which are the most common, symptoms usually subside within a week and all signs and symptoms of illness are gone in a month or so. Severe...

Pathogenesis

Generally, the causative agents reach the bladder by ascending from the urethra. The process is aided by motility of the organisms. Urine is a good growth medium for many species of bacteria. Species of E. coli that infect the urinary system possess pili that attach specifically to receptors on the cells that line the bladder. Experimental evidence indicates that attachment is followed by death and sloughing of the superficial layer of epithelium, followed by penetration of newly exposed cells...

Causative Agents

Bladder infections usually originate from the normal intestinal flora. Specific strains of Escherichia coli cause most cases of bacterial cystitis, accounting for 80 to 90 of cystitis cases in women during the reproductive years and about 70 of all bladder infections. Other enterobacteria such as Klebsiella and Proteus species account for 5 to 10 , and the Gram-positive species, Staphylococcus saprophyticus, accounts for another 5 to 10 of infections in young women. Hospitalized patients are...

Microcheck 252

Normally the urine and urinary tract are free of microorganisms above the entrance to the bladder, but the lower urethra hosts a number of genera of bacteria. During the child-bearing years, a woman's hormones are important in the vagina's resistance to infection, because estrogen promotes growth of lactobacilli and acidic conditions. Which parts of the genitourinary system are normally sterile Name two species of pathogenic bacteria to which the vagina is especially susceptible during...

Applications of Genetic Engineering

Genetic engineering brought biotechnology into a new era by providing a powerful tool for manipulating E. coli and other microorganisms for medical, industrial, or research uses (table 9.2). More recently, techniques that permit the genetic engineering of plants and animals have been developed. Genetic engineering relies on DNA cloning, a process that involves isolating the DNA from one organism, using restriction enzymes to cut the DNA into fragments called restriction fragments, and then...

Apc

Blistery Rash From Test

(d) Antigen-presenting cells present the hapten-peptide complex to sensitized Th1 cells, which secrete cytokines and attract macrophages the macrophages are activated and secrete mediators of inflammation that cause skin lesions. Figure 18.7 Poison Oak Dermatitis Is an Example of Type IV Hypersensitivity Delayed Cell-Mediated (e) Characteristic skin lesions appear after 24 hours, reaching their peak at 48-72 hours after exposure to the plant. cytokines when they come into contact again with the...

Food Spoilage

Food spoilage encompasses any undesirable changes in food. Spoilage microorganisms and their microbial metabolites that cause repugnant tastes and odors, although aesthetically disagreeable, generally are not harmful. This is not surprising when their growth requirements are considered. Most human pathogens grow best at temperatures near 37 C, whereas most foods are usually stored at temperatures well below the normal body temperature. Similarly, the nutrients available in fruits, vegetables,...

Plate Counts

Plate counts measure the number of viable cells in a sample by exploiting the fact that an isolated cell on a nutrient agar plate will give rise to one colony. A simple count of the colonies determines how many cells were in the initial sample (figure 4.13). The two different plating methods, pour-plate and spread-plate, differ in how the suspension of bacteria is applied to the agar plate. As the ideal number of colonies to count is between 30 and 300, and samples frequently contain many more...

X174

*ds, double-stranded ss, single-stranded. *ds, double-stranded ss, single-stranded. Lytic Phage Replication by Double-Stranded DNA Phages In all lytic phage infections, the phage nucleic acid enters the bacterium while its protein coat remains on the outside. Since only nucleic acid enters the cell, the nucleic acid must code for the protein in the phage coat. The nucleic acid is replicated along with phage proteins, resulting in the formation of many virions. At the end of the replication...

Info

Figure 3.20 Typical Shapes of Common Bacteria (a) Coccus (b) rod (c) coccobacillus (d) vibrio (e) spirillum (f) spirochete. Electron micrographs. Figure 3.20 Typical Shapes of Common Bacteria (a) Coccus (b) rod (c) coccobacillus (d) vibrio (e) spirillum (f) spirochete. Electron micrographs. often called a coccobacillus. A short curved rod is called a vibrio (plural vibrios), whereas a curved rod long enough to form spirals is called a spirillum (plural spirilla). A long helical cell with a...

Temperature and Disease

Wide variations exist in the temperature of various parts of the human body. Although the heart, brain, and gastrointestinal tract are near 37 C, the temperature of the extremities may be much lower. For these reasons, some microorganisms can cause disease in certain body parts but not in others. For example, Hansen's disease (leprosy) typically involves the coolest regions of the body (ears, hands, feet, and fingers) because the causative organism, Mycobacterium leprae, grows best at these...

Principles of Bacterial Growth

Bacteria generally multiply by the process of binary fission. After a bacterial cell has increased in size and doubled all of its parts, it divides (figure 4.3). One cell divides into two, those two divide to become four, those four become eight, and so on. In other words, the increase in cell numbers is exponential. Because it is Nester-Anderson-Roberts I I. Life and Death of I 4. Dynamics of Prokaryotic I I The McGraw-Hill 4.2 Principles of Bacterial Growth 85 (8) Isolated colonies develop...

Antigenic Shift

Figure 23.22 Influenza Virus Antigenic Drift and Antigenic Shift With drift, repeated mutations cause a gradual change in the antigens composing the hemagglutinin, so that antibody against the original virus becomes progressively less effective. With shift, there is an abrupt, major change in the hemagglutinin antigens because the virus acquires a new genome segment, which in this case codes for hemagglutinin. Changes in neuraminidase could occur by the same mechanism. Nester-Anderson-Roberts I...

N

Why is it important for a cell that allosteric inhibition be reversible The three central metabolic pathways glycolysis, the pentose phosphate pathway, and the tricarboxylic acid cycle modify organic molecules in a step-wise fashion to form Intermediates with high-energy bonds that can be used to synthesize ATP by substrate-level phosphorylation Intermediates that can be oxidized to generate reducing power Intermediates and end products that function as...

Alcohols

Aqueous solutions of 60 to 80 ethyl or isopropyl alcohol rapidly kill vegetative bacteria and fungi. They do not, however, reliably destroy bacterial endospores and some naked viruses. Alcohol probably acts by coagulating enzymes and other essential proteins and by damaging lipid membranes. Proteins are more soluble and denature more easily in alcohol mixed with water, which is why aqueous solutions are more effective than pure alcohol. Solutions of alcohol are commonly used as antiseptics to...

Anatomy and Physiology

The brain and spinal cord make up the central nervous system (CNS). Both are enclosed by bone the brain by the skull and the spinal cord by the vertebral column (figure 26.1). The network of nerves throughout the body, the peripheral nervous system, is connected with the CNS by bundles of nerve fibers that penetrate the protective bony covering. Nerves can be damaged if the bones are infected at sites of nerve penetration. Motor nerves carry messages from the CNS to different parts of the body...

Archaea that Thrive in Extreme Conditions

Members of the Archaea that have been characterized typically thrive in extreme environments that are otherwise devoid of life. These include conditions of high heat, acidity, alkalinity, and salinity. An exception to this attribute is the methanogens, which inhabit anaerobic niches shared with members of the Bacteria. Because of their intimate association with bacteria, the methanogens were discussed earlier in the chapter. The Archaea fall into two broad phylogenetic groups the Euryarchaeota...

Review Q

Name the prokaryotic groups in the microbial world. 2. List five beneficial applications of bacteria. 3. Name three non-living groups in the microbial world and describe their major properties. 4. In the designation Escherichia coli O157 H7, what is the genus What is the species What is the strain 5. Where would you go to isolate members of the Archaea 6. How might you distinguish a prokaryotic cell from a eukaryotic cell 7. Give three reasons that life could not exist on earth without the...

Mucous Membranes

The cells of the mucous membranes, or mucosa, are constantly bathed with mucus and other secretions that help wash microbes from the surfaces. Some mucous membranes have mechanisms that propel microorganisms and viruses, directing them toward areas where they can be eliminated more easily. For example, peristalsis, the rhythmic contractions of the intestinal tract that propels food and liquid, also helps expel microbes. The respiratory tract is lined with ciliated cells the hairlike cilia...

Jex

(a) Chemoattractants, such as C5a, attract phagocyte to organisms to be ingested (b) C3b coats organisms and attaches to C3b receptors on phagocyte (b) C3b coats organisms and attaches to C3b receptors on phagocyte (g) Contents of phagolysosome eliminated by exocytosis (c) Organism is engulfed into a phagosome fuses with lysosome to produce phagolysosome (e) Organism is killed within the phagolysosome (f) Digestion and breakdown of organism within phagolysosome (c) Organism is engulfed into a...

Selective Media

Selective media inhibit the growth of organisms other than the one being sought. For example, Thayer-Martin agar is used to isolate Neisseria gonorrhoeae from clinical specimens. This is chocolate agar to which three or more antimicrobial drugs have been added. The antimicrobials inhibit fungi, Gram-positive bacteria, and Gram-negative rods. Because these drugs do not inhibit most strains of N. gonorrhoeae, they allow growth with little competition from other organisms. Table 4.6 Ingredients in...

Review Questions

Describe why a microbial mat has green, pink, and black layers. 2. Why do lakes in temperate regions stratify during the summer months 3. Why is there a high concentration of microbes in the rhizosphere 4. What dictates whether a form of an element is suitable for use as an energy source versus a terminal electron acceptor 5. Why does wood resting at the bottom of a bog resist decay 6. What is the importance of nitrogen fixation 7. Describe the relationship between ammonia oxidizers and nitrite...

Nosocomial Infections

A hospital can be seen as a high-density population made up of unusually susceptible people where the most antimicrobial-resistant and virulent pathogens can potentially circulate. Considering this, it is not surprising that hospital-acquired infections, or nosocomial infections, have been a problem since hospitals began (nosocomial is derived from the Greek word for hospital). Modern medical practices, however, including the extensive use of antimicrobial drugs and invasive therapeutic...

IgA

The monomeric form of IgA accounts for about 10 to 13 of antibodies in the blood of healthy individuals. Most IgA antibodies, however, are the secreted form, called secretory IgA (sIgA). In fact, IgA is the most abundant immunoglobulin class produced, even though it makes up only a small fraction of the antibodies in blood. The secreted form is important in mucosal immunity and is found on the mucous membranes that line the gastrointestinal, genitourinary, and respiratory tracts and in...

Causative Agent For Instrument Error Measurement

Microscopic observation all cells in large square counted. Sample added here. Whole grid has 24 large squares, a total area of 1 sq mm and a total volume of 0.02 mm3. 4.6 Methods to Detect and Measure Bacterial Growth 97 Table 4.7 Methods Used to Measure Bacterial Growth Direct microscopic count Cell-counting instruments Membrane filtration Most probable number Total weight Chemical constituents Measuring Cell Products Used to determine total number of cells can be used for those bacteria that...

Viral Diseases of the Lower Alimentary System

Viral infections of the lower alimentary system represent a major illness burden on all age groups. Both the intestine and accessory organs such as the liver can be affected. At least five different groups of viruses can cause epidemic gastroenteritis, resulting in millions of cases each year in the United States. More than six different viruses can cause hepatitis, meaning inflammation of the liver. Hepatitis A virus (HAV), hepatitis B virus (HBV), and hepatitis C virus (HCV) account for most...

Mechanisms of Eukaryotic Pathogenesis

Pathogenesis of eukaryotic cells including fungi and protozoa include the same basic scheme as that of bacterial pathogens colonization, evasion of host defenses, and damage to the host. The mechanisms, however, are generally not well understood. Most fungi, such as yeasts and molds, are saprophytes, meaning that they acquire nutrients from dead and dying material those that can cause disease are generally opportunists, although notable exceptions exist. A group of fungi referred to as...

Causative Agent Of Cytomegalovirus

Cytomegalovirus (CMV) is a member of the herpesvirus family, which includes herpes simplex virus, Epstein-Barr virus, and varicella-zoster virus, any of which can cause troublesome symptoms in patients with immunodeficiency. CMV, like other her-pesviruses, is commonly acquired early in life and then remains latent. With impairment of the immune system, the infection activates and can cause severe symptoms. Symptoms of cytomegalovirus disease follow a pattern similar to that of toxoplasmosis....

Aids

AIDS, acquired immunodeficiency syndrome, unquestionably the most important sexually transmitted disease of the twentieth century, is covered briefly here and more fully in chapter 29. The AIDS epidemic was first recognized in the United States in 1981. Figure 25.20 The AIDS Pandemic Continues Without Letup During 1998 alone an estimated 5.8 million people became newly infected with the human immunodeficiency virus, and most of them will ultimately die of AIDS. Figure 25.20 The AIDS Pandemic...

Gccggaaugcugcuggc

Aspartic acid threonine leucine glycine 6. Allolactose induces the lac regulon by binding to a(n) A. operator. B. repressor. 7. Under which of the following conditions will transcription of the lac operon occur A. Lactose present glucose present B. Lactose present glucose absent C. Lactose absent glucose present D. Lactose absent glucose absent 8. Which of the following statements about gene expression is false A. More than one RNA polymerase can be transcribing a specific gene at a given time....

Microcheck 133

Bacterial genes from a donor can be transferred to recipient bacteria following the incorporation of bacterial genes in place of phage genes in the virion. After the phage lyse the donor bacteria and infect the recipient cells, the bacterial genes are integrated into the chromosome of the recipient cell, the process of transduction. There are two types of transduction generalized, in which any gene of the host can be transferred and specialized, in which only the gene near the site at which the...

The Ecology of Lyme Disease

Yme disease is often referred to as one of the emerging diseases. Unrecognized in the United States before 1975, it is ' now the most commonly reported vector-borne disease. Because of the seeming explosion in the numbers of Lyme disease cases, and its apparent extension to new geographical areas, the ecology of Lyme disease is under intense study. In the northeastern United States, large increases in white-footed mouse populations occur in oak forests during years in which there is a heavy...

Bacterial Infections of the Upper Respiratory System

A number of different species of bacteria can infect the upper respiratory system. Some, such as Haemophilus influenzae and -hemolytic streptococci of Lancefield group C, can cause sore throats but generally do not require treatment because the bacteria are quickly eliminated by the immune system. Other infections require treatment because they are not so easily eliminated and can cause serious complications. Strep Throat (Streptococcal Pharyngitis) Sore throat is one of the most common reasons...

HIV Disease

Almost everyone who becomes infected with HIV develops HIV disease, marked by slow destruction of their immune system, eventually ending in AIDS. The first symptoms of HIV disease appear after an incubation period of 6 days to 6 weeks and usually consist of fever, headache, sore throat, muscle aches, enlarged lymph nodes, and a generalized rash. Some subjects develop central nervous system symptoms ranging from moodiness and confusion to seizures and paralysis. These symptoms constitute the...

Causative Agent

Dental caries is caused principally by Streptococcus mutans and closely related species. The bacteria live only on the teeth and cannot colonize the mouth in the absence of teeth. They produce lactic acid as a by-product of their metabolism of sugars, and unlike many other bacteria, they thrive under acidic conditions below pH 5. Another important feature is that they produce insoluble extracellular glucans from sucrose, but not from other sugars. Glucans, polysaccharides composed of repeating...

O N S

Name three food products produced with the aid of microorganisms. 8. In photosynthesis, what is encompassed by the term light-independent reactions 9. Unlike the oxygenic phototrophs, the anoxygenic phototrophs do not evolve oxygen (O2). Why not 10. What is the role of transamination in amino acid biosynthesis 166 Chapter 6 Metabolism Fueling Cell Growth Multiple Choice 1. Which of these environmental factors does not affect general enzyme activity A. Temperature B. Inhibitors C. Coenzymes D....

Chanchroid Causative Agent

Most of the bacteria that cause STDs survive poorly in the environment and require intimate contact for transmission. 1. Gonorrhea is caused by Neisseria gonorrhoeae, has been generally declining in incidence, but it is still one of the most commonly reported bacterial diseases. (Figures 25.8,25.9) 2. Men usually develop painful urination and thick pus draining from the urethra women may have similar symptoms, but they tend to be milder and are often overlooked. 3. Expression of different...

Chipmunks In Medical Research

During epidemic viral encephalitis, only a minority of those infected develop encephalitis. Others develop viral meningitis, fever and headache only, or no symptoms at all. These diseases are all zoonoses maintained in nature in birds or rodents, humans being an accidental host. In the United States, LaCrosse encephalitis virus usually causes most of the reported encephalitis cases. In its natural cycle (figure 26.13), the LaCrosse virus infects Aedes mosquitoes, which pass it directly from one...

Microcheck

Direct microscopic counts and cell-counting instruments generally do not distinguish between living and dead cells. Plate counts determine the number of cells capable of multiplying membrane filtration can be used to concentrate the sample. The most probable number is a statistical assay based on the theory of probability. Turbidity of a culture is a rapid measurement that can be correlated to cell number. The total weight of a culture and the amount of certain cell constituents can be...

Viral Diseases of the Nervous System

Many different kinds of viruses can infect the central nervous system, including the Epstein-Barr virus of infectious mononucleosis the mumps, rubeola, varicella-zoster, and herpes simplex viruses and more commonly, human enteroviruses and the viruses of certain zoonoses. In most cases, nervous system involvement occurs in only a very small percentage of people infected with the viruses. The next section discusses four kinds of illness resulting from viral central nervous system infections...

Branched Cells That Gather Antigen From Tissues Bring To Lymphctyes

Lobed nucleus granules in cytoplasm ameboid appearance Large eosinophilic granules non-segmented or bilobed nucleus Lobed nucleus large basophilic granules Single nucleus little cytoplasm before differentiation Account for most of the circulating leukocytes few in tissues except during inflammation and in reserve locations Few in tissues except in certain types of inflammation and allergies Basophils in circulation mast cells present in most tissues In circulation they differentiate into either...

Regulating Gene Expression

To cope with changing conditions in their environment, microorganisms have evolved elaborate control mechanisms to synthesize the maximum amount of cell material from a limited supply of energy. This is critical, because generally a microorganism must reproduce more rapidly than its competitors in order to be successful. Consider the situation of Escherichia coli. For over 100 million years, it has successfully inhabited the gut of mammals, where it reaches concentrations of 106 cells per...

Case Presentation

The patient was a 35-year-old man who consulted his physician because of upper abdominal pain.The pain was described as a steady burning or gnawing sensation, like a severe hunger pain. Usually it came on 1 1 2 to 3 hours after eating, and sometimes it woke him from sleep. Generally, it was relieved in a few minutes by food or antacid medicines. On examination, the patient appeared well, without evidence of weight loss.The only positive finding was tenderness slightly to the right of the...

R Plasmid

Figure 8.22 Two Regions of an R Plasmid The R (resistance) genes code for resistance to various antimicrobials the RTF (resistance transfer factor) region codes for plasmid replication and the transfer of the plasmid to other bacteria. Figure 8.22 Two Regions of an R Plasmid The R (resistance) genes code for resistance to various antimicrobials the RTF (resistance transfer factor) region codes for plasmid replication and the transfer of the plasmid to other bacteria.

Terrestrial Habitats

Although microbes may adhere to and grow on a variety of objects on land, the focus in this section will deal with soil, as it is a critical component of terrestrial ecosystems. Extreme terrestrial habitats, such as volcanic vents and fissures, and the extremophiles that inhabit them are described in chapter 11. extreme thermophiles, p. 293 thermophilic extreme acidophiles, p. 294 Human interest in the microbiology of soil stems partly from the ability of microbes to synthesize a variety of...

Biotechnology and Recombinant DNA

n September of 1976, Argentinean newspapers reported a violent shootout that had occurred between soldiers and the JL. occupants of a house in suburban Buenos Aires, leaving the five extremists inside dead. Conspicuously absent from those reports was the identity of the extremists a young couple and their three children, ages six years, five years, and six months. Over the next seven years, similar scenarios recurred as the military junta that ruled Argentina eliminated thousands of its...

The Plasma Membrane

All eukaryotic cells have a cytoplasmic membrane, or plasma membrane, which is similar in chemical structure and fUnction to that of prokaryotic cells. It is a typical phospholipid bilayer embedded with proteins. The lipid and protein composition of the leaflet that faces the cytoplasm, however, differs significantly from that facing the outside of the cell. The same is true for membranes that surround the organelles. The leaflet facing the lumen of the organelle is similar to its counterpart...

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Introduce recombinant molecule into new host Figure 9.2 The Steps of a Cloning Experiment Figure 9.3 Cloning into a High-Copy-Number Plasmid When a gene is inserted into a high-copy-number plasmid, multiple copies of that gene will be present in a single cell, resulting in the synthesis of many more molecules of the encoded protein. Figure 9.3 Cloning into a High-Copy-Number Plasmid When a gene is inserted into a high-copy-number plasmid, multiple copies of that gene will be present in a single...

Type IV Hypersensitivities Delayed Cell Mediated

Harmful effects produced by the mechanisms of cell-mediated immunity are referred to as delayed hypersensitivity. The name reflects the slowly developing response to antigen reactions peak at 2 to 3 days rather than in minutes as in immediate hypersensitivity. As would be expected with cell-mediated responses, T cells are responsible and antibodies are not involved. Delayed hypersensitivity reactions can occur almost anywhere in the body. They are wholly or partly responsible for contact...

The Anatomical Barriers As Ecosystems

The skin and mucous membranes provide anatomical barriers against invading microorganisms, but they also supply the foundation for a complex ecosystem, an interacting biological community. The microbial community that resides on humans is important from a medical standpoint because it offers protection from some disease-causing organisms. At the same time, members of the normal flora are a common cause of infection in people who are immunocompromised. The intimate interactions between the...

Protozoan Diseases

Protozoa infect the blood vascular and lymphatic systems of millions of people worldwide. One example, discussed in an earlier chapter, is Trypanosoma brucei, fundamentally a bloodstream parasite of African animals and cause of African sleeping sickness in humans. Another trypanosome, T. cruzi, causes chagas disease (American trypanosomiasis), often manifest as a chronic heart infection. Protozoans of the genus Leishmania cause visceral leishmaniasis, with enormous splenic enlargement, and a...

Crocheck 193

A primary pathogen can cause disease in an otherwise healthy individual an opportunist causes disease in an immunocompromised host. The course of infectious disease includes an incubation period, illness, and a period of convalescence. Infections may be acute or chronic, latent, localized, or systemic. Why are opportunists causing disease more frequently Give an example of a latent disease. What factors might contribute to a long incubation period

Viruses Prions and Viroids Infectious Agents of Animals and Plants

Transmission electron micrograph (TEM) of rotavirus (x575,000) Ithough scientific reports as early as the eighteenth century suggested that invisible agents might cause * * tumors, not until the early twentieth century did this idea gain strong experimental support. At that time, Dr. Peyton Rous of the Rockefeller Institute caused tumors in healthy chickens by injecting them with a filtered suspension of ground-up cells from tumors of other chickens. These studies were not taken very seriously,...

Mary

An abscess is composed of a collection of pus, which is composed of leukocytes, components of tissue breakdown, and infecting organisms. 2. Abscess formation localizes an infection within tissue to prevent its spread inflammatory cells and clotted blood vessels separate the abscesses from normal tissue. (Figure 27.2) 712 Chapter 27 Wound Infections Anaerobic Wounds 1. Anaerobic conditions are likely to occur in wounds containing dead tissue or foreign material, and those with a narrow opening...

That Complicate Acquired Immunodeficiencies

Certain malignant tumors are associated with HIV disease, organ transplantation, and other acquired immunodeficiency states. Most of these malignancies fall into one of only three types Kaposi's sarcoma, lymphomas, and carcinomas arising from anal or cervical epithelium. They tend to metastasize, meaning jump to new areas, and be difficult to treat. Evidence indicates that viruses are a factor in their causation. A popular theory is that certain viral antigens, perhaps with the aid of...

The Role of Dendritic Cells in TCell Activation

Naive T cells slowly circulate among the secondary lymphoid organs as a means of encountering antigens. Immature dendritic cells, meanwhile, reside in peripheral tissues, such as beneath the skin, gathering various materials from those areas (figure 16.20). The dendritic cells use both phagocytosis and pinocy-tosis to take up particulate and soluble material that could potentially contain foreign protein. After collecting substances from the periphery, the dendritic cells travel to the...

U E S T I O N S

Staphylococcus aureus can be responsible for which of these following conditions A. Impetigo B. Food poisoning C. Toxic shock syndrome D. Scalded skin syndrome E. All of the above 3. The main effect of staphylococcal protein A is to A. interfere with phagocytosis. B. enhance the attachment of the Fc portion of antibody to phagocytes. 4. Which of the following is essential for the virulence of Streptococcus pyogenes A. Protease B. Hyaluronidase C. DNase D. All of the above E. None of the above...

Microcheck 253

Situations that interfere with the normal flow of urine predispose to urinary system infections. Bladder infections are common, especially in women, caused by bowel bacteria ascending from the urethra. Pyelonephritis is a feared complication. Leptospirosis is a widespread zoonosis spread by urine, in which the kidneys are infected from the bloodstream. Usually Wafer or animal urine contaminated with Leptospira sp. splashes onto mucous membrane or abraded skin (2) The bacteria infect the...

Putrefying Agents

Figure 30.4 Growth of Microbial Populations in Unpasteurized Raw Milk at Room Temperature Production of acid causes souring and encourages growth of fungi. Eventually bacteria digest the proteins, causing putrefaction. Figure 30.4 Growth of Microbial Populations in Unpasteurized Raw Milk at Room Temperature Production of acid causes souring and encourages growth of fungi. Eventually bacteria digest the proteins, causing putrefaction. and then a third. An example of such a microbial succession...

Rabies

In the United States, immunization of dogs against rabies has practically eliminated them as a source of human disease. The rabies virus remains rampant among wildlife, however, a constant threat to non-immunized domestic animals and humans. Many questions remain about the pathogenesis of rabies, and no effective treatment exists for the disease. Rabies is one of the most feared of all diseases because its terrifying symptoms almost invariably end with death. Like many other viral diseases, it...

The Nature of Antigens

The term antigen was initially coined in reference to compounds that elicited the production of antibodies it is derived from the descriptive expression antibody generator. The compounds observed to induce the antibody response are recognized as being foreign to the host by the adaptive immune system. They include an enormous variety of materials, from invading microbes and their various products to plant pollens. Today, the term antigen is used more broadly to describe any molecule that reacts...

Transmissible Spongiform Encephalopathy in Humans

Transmissible spongiform encephalopathy is rare in humans, occurring in only 0.5 to 1 case per million people. Most cases occur sporadically as Creutzfeld-Jakob disease, although there are other forms of the disease that run in families. Another form, kuru, is associated with cannibalism, as formerly practiced by some New Guinea natives. Early symptoms include vague behavioral changes, anxiety, insomnia and fatigue, which progress over weeks or months to the hallmarks of the disease, muscle...

Hsv2

Varicella-zoster virus (herpesvirus family) Cytomegalovirus (CMV herpesvirus family) Usually subclinical except in fetus or immunocompromised host CMV pneumonia, eye infections, mononucleosis-like symptoms Salivary glands, kidney epithelium, leukocytes Epstein-Barr virus (herpesvirus family) B cells, which are involved in antibody production Chapter 14 Viruses, Prions, and Viroids Infectious Agents of Animals and Plants Chapter 14 Viruses, Prions, and Viroids Infectious Agents of Animals and...

Biogeochemical Cycling and Energy Flow

Biogeochemical cycles are the cyclical paths that elements take as they flow through living (biotic) and non-living (abiotic) components of ecosystems. These cycles are important, because a fixed and limited amount of the elements that make up living cells exists on the earth and in the atmosphere. Thus, in order for an ecosystem to sustain its characteristic life forms, elements must continuously be recycled. For example, if the organic carbon that animals use as an energy source and exhale as...

Summary

26.1 Anatomy and Physiology (Figure 26.1) 1. The brain and spinal cord make up the central nervous system (CNS) the peripheral nervous system is composed of motor nerves and sensory nerves. 2. Cerebrospinal fluid is produced by structures in cavities inside the brain and flows out over the brain and spinal cord. 3. Meninges are the membranes that cover the surface of the brain and spinal cord. Pathways to the Central Nervous System 1. Infectious agents can reach the CNS by way of the...

Using Phenotypic Characteristics to Classify Prokaryotes

Traditionally, relatedness of different prokaryotes has been decided by comparing their phenotypic characteristics. Numerical taxonomy determines relatedness based on the percentage of characteristics that two groups have in common. In this approach, the investigator conducts a large number of tests to determine whether certain features are present or absent in an organism. These tests include such characteristics as the ability to degrade lactose, the ability to form endospores, and the...

Aquatic Habitats

Oceans, covering more than 70 of the earth's surface, are the most abundant aquatic habitat, representing about 95 of the global water. They are the marine environment. Although lakes and rivers, the fresh water environments, represent only a small fraction of the total water, they are important sources of fresh water. Deep lakes and oceans have characteristic zones that influence the distribution of microbial populations. The uppermost layer, where sufficient light penetrates, supports the...

Microcheck 159

Fever results when macrophages release pro-inflammatory cytokines this occurs when the toll-like receptors on the macrophages are engaged by microbial products. What is an endogenous pyrogen What is an exogenous pyrogen How does fever inhibit the growth of pathogens Syphilis was once treated by intentionally infecting the patient with the parasite that causes malaria, a disease characterized by repeated bouts of fever, shaking, and chills. Why would this treatment cure syphilis

Causative Agent In Morbid Pregnancy-related Outcomes

Figure 16.6 Protective Outcomes of Antibody-Antigen Binding Figure 16.6 Protective Outcomes of Antibody-Antigen Binding is recognized by receptors in the placenta, permitting transport across to the fetus. Since IgG production is not optimal until the secondary response, women who have not been exposed to certain disease-causing agents that can infect and damage the fetus are warned to take extra precautions during pregnancy. For example, pregnant women are advised not to eat raw meat or become...

Viruses and Animal Tumors

As pointed out in the Glimpse of History, viruses were implicated in causing tumors in chickens in the early twentieth century. Retroviruses are the most important tumor viruses in animals, whereas in humans, DNA viruses are the most important. Tumor Viruses and Cell Transformation An understanding of the mechanism by which viruses cause tumors in animals was given a big boost when it was observed that tumor viruses could rapidly change the properties of human cells growing in cell culture....

Using Chemicals to Destroy Microorganisms and Viruses

Germicidal chemicals can be used to disinfect and, in some cases, sterilize. Most chemical germicides react irreversibly with vital enzymes and other proteins, the cytoplasmic membrane, or viral envelopes, although their precise mechanisms of action are often not completely understood (figure 5.6). Although generally less reliable than heat, these chemicals are suitable for treating large surfaces and many heat-sensitive items. Some are sufficiently non-toxic to be used as antiseptics. Those...

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Most human tumors are not caused by viruses but by mutations in certain genes. The most common viral cause of tumors in humans is DNA tumor viruses. One retrovirus is known to cause a rare human tumor. Name three viruses that cause tumors in humans. Name a tumor common in AIDS patients and the virus that causes it. Why is it not surprising that AIDS patients frequently suffer a viral-induced tumor

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Mutations and transfer of genetic information have enabled microorganisms to develop resistance to each new antimicrobial drug that has been developed. Drug resistance affects the cost, complications, and outcomes of medical treatment. Slowing the emergence and spread of bacteria involves the cooperation of health care personnel, educators, and the general public. Explain how using a combination of two antimicrobial drugs helps prevent the development of spontaneously resistant mutants. Explain...

Concerns Regarding DNA Technologies

Advent of any new technology should bring scrutiny over the safety and efficacy of the procedures. When recombinant DNA technologies first allowed the cloning of genes over two decades ago, controversies swirled about their use and possible abuse. Even the scientists who developed the technologies were concerned about potential dangers in gene cloning. In response, the National Institutes of Health (NIH) formed the Recombinant DNA Advisory Committee (RAC) to develop a set of guidelines for...

Using Microorganisms to Nourish the World

The world's steadily increasing population mandates the efficient use of finite natural resources and the development of new protein supplies to nourish that growing populace. One potential solution that addresses both of these needs is to cultivate microorganisms as a protein source, employ- ing industrial by-products currently considered wastes as the growth medium. The term single-cell protein or SCP was coined in the 1960s to describe the use of unicellular organisms such as yeast and...

The Cells of the Immune System

The cells of the immune system can move from one part of the body to another, traveling through the body's circulatory systems like vehicles on an extensive interstate highway system. They are always found in normal blood, but their numbers usually increase during infections, recruited from reserves of immature cells that develop in the bone marrow. Some cells play dual functions, having crucial roles in both innate and adaptive immunity. The formation and development of blood cells is called...

Genetically Engineering Eukaryotic Cells

Transferring genes into most eukaryotic cells is considerably more difficult than transferring them into prokaryotic cells. This is particularly true with plant and animal cells. Vectors Used to Transfer DNA into Eukaryotic Cells Like the vectors used for cloning DNA in bacterial cells, vectors used to transfer DNA into eukaryotic cells generally have a selectable marker and a unique restriction enzyme site. Frequently, they also have a characteristic that allows the Bacterial cells plated on...

Micrococcus Species Status Epilepticus

Obligate aerobes generate energy exclusively by respiration. Micrococcus species are Gram-positive cocci found in soil and on dust particles, inanimate objects, and skin. (Figure 11.12) Mycobacterium species are widespread in nature. Although they have a Gram-positive type of cell wall, they stain poorly they are acid-fast. Mycobacterium species cause tuberculosis and Hansen's disease (leprosy). Pseudomonas species are Gram-negative rod-shaped bacteria that are widespread in nature and have...

Interactions of Animal Viruses with Their Hosts

For bacterial viruses, the host organism is a single cell, and so other kinds of cells do not affect the course of the infection. In the case of animals, however, the outcome of viral infection depends on many factors that are independent of the infected cell. Of special importance are the defense mechanisms of the host, such as the presence of protective antibodies that can confer immunity against a virus ordinarily lethal to an individual without such immunity. Devastating epidemics of...

Bacteria that Derive Nutrients from Other Organisms

Bacteria Cycle Atacting

Some bacteria obtain nutrients directly from other organisms. Bdellovibrio species do this by preying on other bacteria, attacking them and digesting their contents, eventually killing them. Bioluminescent bacteria use another tactic they have established relationships with fish and squid in which the animal provides nutrients and protection while the bacterium provides a source of luminescence. Legionella species can live intracellularly within the protected confines of protozoa. Bdellovibrio...

Sterilization Using Pressurized Steam

Pressure cookers and their commercial counterpart, the autoclave, heat water in an enclosed vessel that achieves temperatures above 100 C (figure 5.3). As heated water in the vessel forms steam, the steam causes the pressure in the vessel to increase beyond atmospheric pressure. The higher pressure, in turn, increases the temperature at which steam forms. Whereas steam produced at atmospheric pressure never exceeds 100 C, steam produced at an additional 15 psi (pounds square inch) is 121 C, a...

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Rotaviruses are the leading cause of viral gastroenteritis in infants and children, and they also are a common cause of traveler's diarrhea. Norwalk viruses cause almost half the viral gastroenteritis in children and adults. Hepatitis A is transmitted by the fecal-oral route and is preventable by gamma globulin and an inactivated vaccine. Hepatitis B, transmitted by exposure to blood and by sexual intercourse, is preventable by a vaccine produced in yeast. A combination hepatitis A and...

Microcheck 245

Vibrios, Campylobacter jejuni, and enterobacteria account for most intestinal bacterial infections. Pathogenic mechanisms include attachment, toxin production, cell invasion, and destruction of microvilli. Gastroenteritis can be caused either by infectious microorganisms consumed with the food or by toxic products of microbial growth in food. Some microbial toxins alter the secretory function of cells in the small intestine without killing or visibly damaging them. Unsuspected human carriers...

Cousetive Agent Of Cilia

The phylum Ciliophora, or the ciliates, includes organisms that have cilia. The cilia are similar in construction to the flagella and usually completely cover the surface of an organism. Most often, they are arranged in distinct rows and are connected to one another by fibrils known as kinetodesma. Cilia beat in a coordinated fashion in waves across the body of the protozoan. A beat of one cilium affects the cilia immediately around it, but there is no evidence that the connecting fibrils aid...

Gram Negative Septicemia

Septicemia is a common nosocomial illness, with an estimated 400,000 cases occurring in the United States each year. Approximately 30 of of the cases are caused by Gram-negative bacteria. Endotoxin release by Gram-negative bacteria can lead to shock and death. The symptoms of septicemia include violent shaking chills and fever, often accompanied by anxiety and rapid breathing. If septic shock develops, urine output drops, the respirations and pulse become more rapid, and the arms and legs...

Overview of the Innate Defenses

First-line defenses are the barriers that separate and shield the interior of the body from the surrounding environment they are the initial obstacles that microorganisms must overcome to invade the tissues. The anatomical barriers, which include the skin and mucous membranes, not only provide physical separation, but they are often bathed in secretions containing substances that have antimicrobial properties (figure 15.1). Characteristics of the components of innate immunity, including the...

Characteristics to Identify Prokaryotes

Increasingly, genotypic characteristics are being used to identify microorganisms, particularly those that are difficult to cultivate. DNA probes and polymerase chain reaction (PCR) can both be used to detect nucleotide sequences that are unique to a given organism. DNA sequencing has made identification possible of organisms that cannot be grown in culture. nucleic acid probe, pp. 225,236 polymerase chain reaction, pp. 229,239 sequencing, pp. 229,237 Nucleic Acid Probes to Detect Specific...

Membrane Bound Organelles

Nucleus Freeze Fracture

The presence of membrane-bound organelles is an important feature that sets eukaryotic cells apart from their prokaryotic counterparts. The predominant distinguishing feature of the eukaryotic cell is the nucleus, which contains the DNA. Enclosing this structure are two concentric lipid bilayer membranes the inner membrane and the outer membrane. These membranes make up the nuclear envelope. Spanning the membranes are complex protein structures that form nuclear pores, allowing large molecules...

Examples of Emerging Antimicrobial Resistance

Some of the problems associated with the increasing resistance of bacteria to antimicrobial drugs are highlighted by the following examples. One of the most dramatic examples of antimicrobial resistance is the enterococci, a group of bacteria that are part of the normal intestinal flora and a common cause of nosocomial infections. Enterococci are intrinsically less susceptible to many common antimicrobials. For example, their penicillin-binding proteins have low affinity for certain b-lactam...

Methanogens Often Grow In Association With

Methanogens are found in anaerobic environments where hydrogen gas and carbon dioxide are available. Because these gases are generated by chemoorganotrophs during the fermentation of organic material, methanogens often grow in association with these microorganisms. Methanogens, however, are generally not found in environments that contain high levels of sulfate, nitrate, or other inorganic electron acceptors. This is because microorganisms that oxidize hydrogen gas using these electron...

A B C D E

370 Chapter 14 Viruses, Prions, and Viroids Infectious Agents of Animals and Plants Applications 1. You are a scientist at a pharmaceutical company in charge of developing drugs against HIV. Discuss four possible targets for drugs that might be effective against this virus. 2. Researchers debate the evolutionary value to the virus of its ability to cause disease. Many argue that viruses accidentally cause disease and only in animals that are not the natural host. They state that this strategy...

Anaerobic Chemoorganotrophs Anaerobic Respiration

Chemoorganotrophs oxidize organic compounds such as glucose to obtain energy. Like the chemolithotrophs, chemoorgan-otrophs that grow anaerobically employ a terminal electron acceptor other than O2. Sulfur and sulfate are common inorganic compounds used as a terminal electron acceptor by these organisms. Sulfur- and Sulfate-Reducing Bacteria When sulfur compounds are used as a terminal electron acceptor, they become reduced to form hydrogen sulfide, the compound responsible for the rotten-egg...

Approaches to Control

The processes used to control microorganisms are either physical or chemical, though a combination of both may be used. Physical methods include heat treatment, irradiation, filtration, and mechanical removal (washing). Chemical methods use any one of a variety of antimicrobial chemicals. The method chosen depends on the circumstances and resulting degree of control required. Definitions related to microbial control are summarized in table 5.1. The process of removing or destroying all...