Tags: Aminoglycoside

Giardia: Clinical Syndromes

After ingestion of G lamblia cysts, 5-15% of patients will have asymptomatic cyst passage, and 25-50% of patients will have diarrhea. From 35% to 70% of these patients will have no evidence of infection. The three manifestations of infection include asymptomatic cyst passage, self-limited diarrhea, and chronic diarrhea with associated malabsorption and weight loss. Factors related to each of these manifestations are unknown but are believed to be related to specific host factors, parasite load, and virulence variation among G lamblia isolates.

Actinomyces

Disease occurs when mechanical insult disrupts the mucosal barrier or organisms gain access to privileged sites. For example, actinomycosis commonly occurs after dental procedures, trauma, surgery, or aspiration. Actinomyces israelii causes the majority of human disease owing to this genus, but other species, including Actinomyces naeslundii, Actinomyces viscosus, Actinomyces enksonii, Actinomyces odontolyticus, and Actinomyces meyeri have also been implicated. Actinomycosis is threefold more common in men than women.

Other Mycobacteria

The increasingly relative importance of the atypical mycobacteria, many of which are ubiquitous in the environment, was recognized with the decline in tuberculous disease. Generally, atypical mycobacteria are unusual causes of disease in patients who are immunocompetent but can in immunocompromised hosts such as AIDS and cancer patients.

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.

Yersiniosis

Conditions that are associated with increased risk for Yersinia spp. infections (yersiniosis) include iron overload states (such as in patients who receive chronic blood transfusions or those with hemochromatosis) and the use of desferrioxamine, a bacterial siderophore. Infections caused by Y enterocolitica are more common in children than adults.

Tularemia

Francisella tularensis is the causative agent of tularemia (also called rabbit fever or deerfly fever), an infectious disease that occurs primarily in animals. It may occasionally cause human disease, which most often manifests itself by one or more skin lesions, regional lymphadenopathy, fever, and constitutional symptoms.

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.

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.