Tags: Vancomycin

Important Anaerobes

Anaerobic bacteria are the predominant component of the normal microbial flora of the human body. The following sites harbor the vast majority of them:

Toxin-Mediated Infections

Tetanus is a disease of global incidence produced by the toxin of Clostridium tetani. The risk of acquiring it increases in people > 60 years of age and in neonates, especially in Third World countries where poor sanitary conditions predispose to umbilical stump contamination. Immunization campaigns have played a crucial role in bringing about the observed decreasing incidence in the United States. The pathogenesis of tetanus involves the absorption of preformed toxin, or, less commonly, invasion of toxin-producing organisms from contaminated wounds; it may complicate surgical wounds colonized with C tetani.

Haemophilus, Bordetella, & Branhamella Species

Before 1990, strains of Haemophilus influenzae type b were found in the upper respiratory tract of 3-5% of children and a small percentage of adults. Colonization rates with type-b strains are even lower now, reflecting routine immunization of infants against H influenzae type b. Non-type-b encapsulated H influenzae are present in the nasopharynx of < 2% of individuals, whereas nonencapsulated (nontypable [see below]) strains colonize the respiratory tract of 40-80% of children and adults.

Branhamella Catarrhalis: Clinical Syndromes

B catarrhalis causes bronchitis and pneumonia in patients with underlying lung disease, especially chronic obstructive pulmonary disease. It is also a rare cause of invasive disease, including meningitis, endocarditis, bacteremia without a focus, septic arthritis, and cellulitis.

Haemophilus Influenzae: Clinical Syndromes

H influenzae was first isolated during the 1892 influenza pandemic and was originally believed to be the causative agent of influenza. Although subsequent studies revealed the fallacy of this idea, H influenzae has proved to be a common cause of localized respiratory tract and systemic disease, including meningitis, epiglottitis, pneumonia, pyogenic arthritis, cellulitis, otitis media, and sinusitis, among others (Box 1). Meningitis is the most common and serious form of invasive H influenzae type-b disease. In the mid-1980s, before the introduction of effective vaccines, ~ 10,000-12,000 cases of H influenzae type-b meningitis occurred in the United States each year, and 95% of cases involved children < 5 years old.

Helicobacter Pylori

Pathologists have noted spiral bacteria in biopsies and autopsy specimens of gastric mucosa for over 100 years. Their significance was alternately debated and ignored until 1982, when Barry Marshall and Robin Warren cultivated the organism for the first time and suggested that it might be a cause of chronic gastritis and peptic ulcer disease. Although initially called Campylobacter pylori, subsequent taxonomic studies showed that the bacterium was not a true Campylobacter species, and it was renamed Helicobacter pylori.

Neisseria Gonorrhoeae & Neisseria Meningitidis

Neisseria gonorrhoeae was first described by Albert Neisser in 1879, in the ocular discharge and exudate from newborn infants with conjunctivitis. Descriptions of a condition resembling the disease gonorrhea can be found in the written record as early as 130 AD, when Galen created a descriptor for the malady by using the Greek words gonos (seed) and rhoea (flow) to characterize what was believed to be the morbid loss of semen.

Gram-Positive Aerobic Bacilli

L monocytogenes is found in soil, fertilizer, sewage, and stream water; on plants; and in the intestinal tracts of many mammals. It is a foodborne pathogen that causes bacteremic illness and meningoencephalitis, with few if any gastrointestinal manifestations.

Other Bacillus Species

Bacillus species other than B anthracis are found in soil, decaying organic matter, and water, but they are rare causes of disease. Risk factors associated with Bacillus infection include the presence of intravascular catheters, intravenous drug use, sickle cell disease, and immunosuppression — particularly corticosteroid use, transplantation, AIDS, and neutropenia secondary to chemotherapy.

Other Gram-Positive Cocci

Leuconostoc spp. are gram-positive cocci or coccobacilli that grow in pairs and chains; Leuconostoc spp. may be morphologically mistaken for streptococci. They are vancomycin-resistant facultative anaerobes that are commonly found on plants and vegetables and less commonly in dairy products and wine. Leuconostoc spp. have been documented to cause bacteremias, intravenous line sepsis with localized exit site infection and/or bacteremia, meningitis, and dental abscess.