Nutritional Factors that Influence Microbial Growth

Growth of any bacterium depends not only on a suitable physical environment, but also an available source of chemicals to use as nutrients. From these, the cell must synthesize all of the cell components discussed in chapter 3, including lipid membranes, cell walls, proteins, and nucleic acids. These components are made from building blocks such as fatty acids, sugars, amino Table 4.3 Representative Functions of the Major Elements Component of cellular constituents including amino acids,...

Microscopic Techniques Dyes and Staining

Steps Gram Stain Technique

It can be difficult with the bright-field microscope to observe living microorganisms. Most are nearly transparent and often move rapidly about the slide. Consequently, cells are frequently immobilized and stained with dyes. These dyes may be attracted to one or more cellular components. As a result, an entire organism, or its specific parts, can be made to contrast with the unstained background. Many different dyes and staining procedures can be used each has specific applications table 3.2 ....

Non Venereal Genital System Diseases

The genital tract is the portal of entry for numerous infectious diseases, both venereal and non-venereal (venereal, from Venus, the goddess of love non-venereal means not transmitted by making love). This section discusses some examples of non-venereal genital diseases. The term venereal disease (VD), formerly meaning disease transmitted almost exclusively by sexual intercourse, is now often used interchangeably with sexually transmitted disease (STD), which includes all diseases spread by...

Exponential Phase Log Phase

During the exponential or log phase, cells divide at a constant rate and their numbers increase by the same percentage during each time interval. The generation time is measured during this period of active multiplication. Because bacteria are most susceptible to antibiotics and other chemicals during this time, the log phase is important medically. During the initial phase of exponential growth, all the cells' activities are directed toward increasing cell mass. Cells produce compounds such as...

Bacterial Skin Diseases

Only a few species of bacteria commonly invade the intact skin directly, which is not surprising in view of the anatomical and physiological features discussed earlier. Hair follicle infections exemplify direct invasion. Infections originating in hair follicles commonly clear up without treatment. In some instances, however, they progress into severe or even life-threatening disease. Folliculitis, furuncles, and carbuncles represent different outcomes of hair follicle infections. In...

Slime Molds and Water Molds

Cellular Slime Mould Life Cycle Images

The slime molds and water molds used to be considered types of fungus. They are, however, completely unrelated to the true fungi and are good examples of convergent evolution. Convergent evolution occurs when two organisms develop similar characteristics because of adaptations to similar environments and yet are not related on a molecular level figure 12.19 . There are two groups of slime molds, the acellular slime molds and the cellular slime molds. The slime molds are terrestrial organisms...

Microbiology of Solid Waste Treatment

In addition to ridding our environment of wastes in water, we must dispose of the solid wastes that are generated each day. Some of it is inert materials such as glass, metals, and plastics, but a large amount is organic material that is affected by microorganisms. Eliminating waste products from the environment has become an increasingly complex problem. Sanitary Landfills for Solid Waste Disposal Sanitary landfills are widely used to dispose of non-hazardous solid wastes in a manner that...

Characteristics of the Secondary Response

Igg Igm First And Second Exposure

Memory B cells are responsible for the swift and effective reaction of the secondary response, eliminating identical repeat invaders before they cause noticeable harm. Thus, once a person has recovered from a particular disease, he or she generally has long-lasting immunity to that disease. Vaccination exploits this naturally occurring phenomenon. Memory B cells that bind antigen can promptly become activated provided they receive necessary signals from effector T-helper cells. When compared to...

Obligate Intracellular Parasites

Tissue Culture Chlamydia

Obligate intracellular parasites are unable to reproduce outside a host cell. In general, the term only refers to those that infect eukaryotic cells. By living within eukaryotic cells, these bacteria are supplied with a readily available source of compounds they would otherwise need to synthesize for themselves. As a result, most species of these genera have lost the ability to synthesize substances needed for extracellular growth. Bacterial examples include members of the genera Rickettsia,...

Fungal Wound Infections

Sporotrichosis

Fungal infections of wounds are unusual in economically developed countries, except that the yeast Candida albicans can be troublesome in severe burns and in those with wounds and underlying diseases such as diabetes and cancer. This yeast, commonly present among the normal flora and kept in check by it, becomes pathogenic when the competing microorganisms are eliminated, as in individuals receiving antibacterial therapy. Other fungal wound infections are much more common in impoverished people...

Microbiology of Sewage Treatment

Methods Used For Testing Water Nester

Sewage, or wastewater, is composed of all the material that flows from household plumbing systems, including washing and bathing water and toilet wastes. Municipal wastewater also includes industrial wastes. In many cities, storm water runoff that flows into street drains enters the sewage system as well. The most obvious reason that sewage must be treated before discharge is that pathogenic microbes can be transmitted in feces, including those that cause diarrheal diseases and hepatitis. If...

History and Development of Antimicrobial Drugs

To appreciate the unique antibiotic era in which we now live, it is helpful to understand the history and development of these life-saving remedies. The development of Salvarsan by Paul Ehrlich was the first documented example of a chemical used successfully as an antimicrobial medication. The next breakthrough in the developing science of antimicrobial chemotherapy came almost 25 years 508 Chapter 21 Antimicrobial Medications 508 Chapter 21 Antimicrobial Medications Table 21.1 Terms that...

Establishing the Cause of Infectious Disease

The fact that microorganisms and viruses cause infectious disease is now commonly accepted. The evidence that linked microbes to disease was discovered not much more than a century ago, however, when Robert Koch showed that that Bacillus anthracis causes anthrax (see A Glimpse of History). This was an important step forward, because it often allowed people to avoid or control infection. In addition, it led to the development of antimicrobial drugs and other therapies to combat infectious...

Bacteria that Form a Resting Stage

Cyst Forming Azospirillum

Several genera that inhabit the soil can form a resting stage that enables them to survive the dry periods that are typical in many soils. Of these various types of dormant cells, endospores are by far the most resistant to environmental extremes. Bacillus and Clostridium species are common Gram-positive rod-shaped bacteria that form endospores the position of the spore in the cell can be used as an aid in identification (figure 11.16). Clostridium species, which are obligate anaerobes, were...

Prevention and Treatment

Human Penis Infections

Avoidance of sexual intercourse during active symptoms and the use of condoms with a spermicide reduce but do not eliminate the chance of transmission. Spermicidal jellies and creams can inactivate herpes simplex viruses. There is no cure for genital herpes, although medications such as acyclovir and famciclovir Figure 25.18 Genital Warts on the Penis, a Manifestation of Human Papillomavirus Infection Itching, burning pain at the site of infection, painful urination, tiny blisters with...

Reservoirs of Infectious Agents in Hospitals

The organisms that cause nosocomial infections may originate from other patients, the hospital environment, medical personnel, or from the patient's own normal flora. Because of the widespread use of antimicrobial drugs in hospitals, many organisms that cause nosocomial infections are resistant to these medications. Because of the very nature of hospitals, infectious agents are always present. Patients are often hospitalized because they have a severe infectious disease. The pathogens that...

Normal Flora of the Genitourinary System

Normally, the urine and urinary tract above the entrance to the bladder are essentially free of microorganisms the lower urethra, however, has a normal resident flora. Species of Lactobacillus, Staphylococcus (coagulase-negative), Corynebacterium, Haemophilus, Streptococcus, and Bacteroides are common inhabitants. The normal flora of the genital tract of women is influenced by the action of estrogen hormones on the epithelial cells of the vaginal mucosa. When estrogens are present, glycogen is...

Normal Flora of the Skin

Microscopic Arachnid Skin Causes Acne

The skin represents a distinct ecological habitat, analogous to a cool desert, compared to the warm, moist tropical conditions that exist in other body systems. Large numbers of microorganisms live on and in the various components of the normal skin. For example, depending on the body location and amount of skin moisture, the number of bacteria on the skin surface may range from only about 1,000 organisms per square centimeter on the back to more than 10 million in the groin and armpit, where...

Causative Agent Of Cytomegalovirus

Eosinofilos

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....

Characteristics to Identify Prokaryotes

Wet Mounts Clinical Specimens

Phenotypic characteristics such as cell morphology, colony morphology, biochemical traits, and the presence of specific proteins can all be used in the process of identifying microorganisms. Most of these methods do not require sophisticated equipment and can easily be done anywhere in the world. Methods used to identify prokaryotes are summarized in table 10.3. An important initial step in identifying a microorganism is to determine its size, shape, and staining characteristics. Microscopic...

Choose The One True Statement About Gas Gangrene

What characteristics of bite wounds favor anaerobic infections 17. What is the causative agent of cat scratch disease Why is it a threat to patients with AIDS 18. What is a synergistic infection How might one be acquired 20. Why is sporotrichosis sometimes called rose gardener's disease Multiple Choice 1. All of the following are true of Staphylococcus aureus, except A. it is generally coagulase-positive. B. its infectious dose is increased in the presence of a foreign body. C. some strains...

Invasion Breaching the Anatomical Barriers

Membrane Ruffling Typhimurium

Some bacterial pathogens cause disease while remaining on the mucosal surfaces, but many others breach the anatomical barriers. By traversing the epithelial cell barrier and accessing the nutrient-rich tissue, these invading microbes can enjoy an exclusive source of nutrients, multiplying without competition. Skin is the most difficult anatomical barrier for a microbe to penetrate. Bacterial pathogens that invade via this route rely on trauma of some sort that destroys the integrity of the...

Streptococcal Impetigo

Streptococcus Pyogenes

A skin infection characterized by pus production is called pyoderma. Pyodermas can result from infection of an insect bite, burn, scrape, or other wound. Sometimes, the injury is so slight that it is not apparent. Impetigo is the most common type of pyoderma (figure 22.5). Impetigo is a superficial skin infection, involving patches of epidermis just beneath the dead, scaly outer layer. Thin-walled Figure 22.5 Impetigo This type of pyoderma is often caused by Streptococcus pyogenes and may...

Pseudomonas aeruginosa Infections

Pseudomonas Burn Infection

Pseudomonas aeruginosa is an opportunistic pathogen that is widespread in the environment, a major cause of nosocomial infections, and an occasional cause of community-acquired infections, meaning infections acquired outside hospital or other medical facilities. Community-acquired infections include skin rashes from contaminated swimming pools and hot tubs, serious infections of the foot bones from stepping on nails, serious eye infections from contaminated contact lens solutions, heart valve...

Causative Agent Of Worm Infestation

Causal Organism Worm Infestation

Rocky Mountain spotted fever fever, hemorrhagic rash, confusion Lyme disease fever, rash, joint pain, nervous system impairment 316 Chapter 12 The Eukaryotic Members of the Microbial World Storage area Midgut 316 Chapter 12 The Eukaryotic Members of the Microbial World Storage area Midgut Figure 12.21 Internal Anatomy of a Mosquito Note the storage areas that allow ingestion of large amounts of blood and the salivary glands that discharge pathogens into the host. Figure 12.21 Internal Anatomy...

The Commercial Canning Process

Chemical Indicator For Autoclave

The commercial canning process uses pressurized steam in an industrial-sized autoclave called a retort. Conditions of the process are designed to ensure that endospores of Clostridium botulinum are destroyed. This is critical because surviving spores can germinate and the resulting vegetative cells can grow in the anaerobic conditions of low-acid canned foods, such as vegetables and meats, and produce botulinum toxin, one of the most potent toxins known. Because ingestion of even minute amounts...

Microbiologist Who Has Inclined To Accept The Theory Of Spontaneous Generation

C. a nuclear membrane. D. specific shapes. E. genetic information. 8. Nucleoids are associated with 1. genetic information. 2. prokaryotes. 3. eukaryotes. A. 1, 2 B. 2, 3 C. 3, 4 D. 4, 5 E. 1, 5 9. Which of the following are eukaryotes 1. Algae 2. Viruses 3. Bacteria A. 1, 2 B. 2, 3 C. 3, 4 D. 4, 5 E. 1, 5 10. The person best known for his microscopy of microorganisms is 1. The American Society of Microbiology is preparing a Microbe-Free banquet to emphasize the...

Skin Diseases Caused by Fungi

Candida Albicans Cytological

Diseases caused by fungi are called mycoses. Earlier in this chapter, we mentioned the role of normal flora yeast of the genus Malassezia in causing mild skin diseases, such as tinea versicolor. Other fungi are responsible for more serious infections of the skin, although even in these cases the condition of the host's defenses against infection is often crucial. The yeast Candida albicans (figure 22.26) may live harmlessly among the normal flora of the skin, but in some people it invades the...

Fermented Meat Products

Traditionally, fermented meat products, such as salami, pepper-oni, and summer sausage, were produced by enabling the small numbers of lactic acid bacteria naturally present to multiply to the point of dominance. Relying on the natural fermentation of meat is inherently risky, however, because the incubation conditions used to initiate fermentation can potentially support the growth and toxin production of pathogens such as Staphylococcus aureus and Clostridium botulinum. The development and...

Toxic Derivatives of Oxygen O2

Cell Called Shrinkage

Although not toxic itself, O2 can be converted into a number of compounds that are highly toxic. Some of these, such as superoxide (O2 ), are produced both as a part of normal metabolic processes and as chemical reactions involving oxygen and light. Others, such as hydrogen peroxide (H2O2), result from metabolic processes involving oxygen. To survive in an environment containing O2, cells must have enzymes that can convert these toxic compounds to non-toxic forms. The enzyme superoxide...

Cousative Agent Of Hbsag

Hepatitis B is caused by hepatitis B virus (HBV) (figure 24.19a), a member of the hepadnavirus family (hepa-, referring to the liver, and -dna- DNA). The virus contains double-stranded DNA and has a lipid-containing outer envelope. Three important HBV antigens are (1) surface antigen (HBsAg), (2) core antigen (HBcAg), a protein of the nucleocapsid, and (3) e antigen (HBeAg), a soluble component of the viral core. HBsAg is produced during viral replication in amounts far in excess of that needed...

Vaccines and Immunization Procedures

A vaccine is a preparation of a disease-causing agent or its products used to induce active immunity. Vaccines not only protect an individual against disease, they can also prevent diseases from spreading in a population. When a critical portion of a population is immune to a disease, either through natural immunity or vaccination, a phenomenon called herd immunity develops. 17.2 Vaccines and Immunization Procedures 421 This is the inability of an infectious disease to spread because of the...

Case Presentation

The patient was a 24-year-old woman, a surgical nurse, seen in the clinic for evaluation of a needle puncture wound to the hand. Earlier in the day, while assisting in a frantic attempt to revive a man with cardiac arrest, she sustained a deep puncture wound to her right palm from a needle that had accidentally dropped into the bedclothes. The needle was visibly contaminated with blood. She immediately washed her hand thoroughly with soap and water, applied an antiseptic, and dressed the...

Epidemiology Causative Agent

Giant Cell Inclusion Disease

HSV is extremely widespread and infects up to 90 of some U.S. inner-city populations, usually resulting in mild, if any, symptoms. An estimated 20 to 40 of Americans suffer recurrent herpes simplex. The virus is transmitted primarily by close physical contact, although it can survive for several hours on plastic and cloth. The greatest risk of infection is from contact with lesions or saliva from patients within a few days of disease onset, because at this time large numbers of virions are...