Tags: Allergy

Dermatophytes

Dermatophytes are molds that infect keratinized tissues including skin, hair, and nails. Whereas 40 dermatophyte species are known to infect humans, only about 15 of these are common causes of disease. These organisms belong to three genera, Microsporum, Trichophyton, and Epidermophyton. Because these fungi have such similar infectivity, morphology, and pathogenicity, they are often categorized according to the clinical syndrome and the preferred anatomic site with which they are associated, such as tinea capitis, tinea pedis, etc.

Histoplasma Capsulatum

Histoplasma capsulatum, the etiologic agent of histoplasmosis, is an endemic, dimorphic fungus that causes a wide spectrum of disease in both immunocompetent and immunocompromised individuals. It is found in temperate zones around the world. In the United States, it is endemic within the Ohio and Mississippi River Valleys.

Brucella, Francisella, Pasteurella, Yersinia, & Hacek

Brucellosis (also called undulant fever, Mediterranean fever, Malta fever) is an infection that causes abortion in domestic animals. It is caused by one of six species of Brucella coccobacilli. It may occasionally be transmitted to humans, in whom the disease could be acute or chronic with ongoing fever and constitutional symptoms without localized findings.

Infection in Patients With Aids

Paeruginosa infections may occur in patients with AIDS. Risk factors for infection include a CD4 count of < 100 cells/mL3, neutropenia or functional neutrophil defects, intravascular catheterization, hospitalization, and prior use of antibiotics including ciprofloxacin or trimethoprim-sulfamethoxazole. Many cases are community acquired. Bacteremia is common, and the lung or an intravenous catheter is the most frequent portal of entry.

Enterococci

Enterococci are able to grow and survive under harsh conditions and can be found in soil, food, water, and a wide variety of animals. The major habitat of these organisms is the gastrointestinal tract of humans and other animals, where they make up a significant portion of the normal gut flora. Most enterococci isolated from human stools are E faecalis, although E faecium are also commonly found in the human gastrointestinal tract. Small numbers of enterococci are occasionally found in oropharyngeal and vaginal secretions and on the skin, especially in the perineal area.

Streptococcus Pneumoniae

S pneumoniae may exist in humans as either a nasopharyngeal colonist or as a pathogen in one of many clinical syndromes (Box 1). Although S pneumoniae has been found in other mammals, humans are thought to be the principal reservoir. As a colonist, S pneumoniae is found in up to 40% of children and 10% of adults.

Staphylococci

Staphylococcus aureus colonizes the human skin, vagina, nasopharynx, and gastrointestinal tract. Colonization occurs shortly after birth and may be either transient or persistent. Published studies differ widely in estimates of the prevalence of S aureus carriage.

Primary Bacteremia & Endocarditis

Staphylococci (both S aureus and CoNS) have emerged as the two most common organisms cultured from patients with primary bloodstream infections. The term “primary bacteremia” refers to positive blood cultures without an identifiable anatomic focus of infection. Differentiation of primary bacteremia from infective endocarditis (IE), in which infection of the cardiac valves leads to continuous bacterial seeding of the bloodstream, may challenge even the most experienced clinician. Primary S aureus bacteremia is associated with insulin-dependent diabetes, the presence of a vascular graft, and, most significantly, the presence of an indwelling intravascular catheter.