Bacterial Infections

Bartonella

Essentials of Diagnosis Key signs and symptoms include dermal lesion (bacillary angiomatosis and chronic phase of Bartonella bacilliformis infection); papule at inoculation site followed by proximal lymphadenopathy (cat scratch disease); fever, bacteremia, acute hemolytic anemia (acute phase of B bacilliformis infection); persistent or relapsing fever (fever and bacteremia/endocarditis). Predisposing factors include louse exposure, low income, and homelessness (Bartonella quintana-associated bacillary angiomatosis, fever, and bacteremia/endocarditis); cat exposure (cat scratch disease and Bartonella henselae-associated bacillary angiomatosis, fever and bacteremia/endocarditis); sandfly exposure in endemic areas of South American Andes (B bacilliformis infection). History of HIV or immunocompromise (bacillary angiomatosis). Key laboratory findings include small, curved, pleomorphic weakly gram-negative bacilli, best visualized with Warthin-Starry silver …

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Fever & Bacteremia/Trench Fever/Endocarditis

The four Bartonella species that are pathogenic for humans are capable of causing sustained or relapsing bacteremia accompanied by only fever (Table 1). All except B bacilliformis also cause endocarditis. After B quintana enters the body through broken skin from the excreta of the infected human body louse (Pediculus humanus), there is an incubation period of between 5 and 20 days before the onset of trench fever. Patients complain of fever, myalgias, malaise, headache, bone pain — particularly of the legs, and a transient macular rash. Usually the illness continues for 4-6 weeks. Sustained or recurrent bacteremia is common, with or without symptoms. The form of trench fever described in the …

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Bacillary Angiomatosis

A. Signs and Symptoms. The most common manifestation of bacillary angiomatosis is a dermal lesion (Table 1). Three types of lesions are seen: cutaneous papules, subcutaneous nodules, and hyperpigmented plaques, in decreasing order of frequency. Papules are usually red-purple in color and range in size from a few millimeters to several centimeters, often surrounded by a collarette of scale. They vary in number, are often friable and bleed easily, are occasionally tender, and may resolve spontaneously even in immunosuppressed patients. These lesions are easily removed by curettage. Slight hyperpigmentation and induration may persist. Subcutaneous nodules or lobules are the second most common presentation and may vary markedly in size and number. …

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Rickettsialpox

Essentials of Diagnosis Eschar at site of mite bite. Regional lymphadenopathy. Generalized erythematous papulovesicular eruption on the trunk, extremities, and mucous membranes 9-14 days after exposure. Systemic symptoms including chills, fever, myalgias, anorexia, and photophobia. Prediposing factors include urban dwelling in close proximity to house mice. Serology for R rickettsii will cross-react with antibodies to Rickettsia akari. General Considerations Rickettsialpox has been reported infrequently in the United States. This disease is a mild, self-limited illness caused by R akari and is transmitted to humans by a house mite. Both the house mouse and house mite are reservoirs for the organism. Clinical Findings A painless papule develops 7-14 days after the mite …

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Rocky Mountain Spotted Fever (RMSF)

Essentials of Diagnosis Key symptoms and signs: abrupt onset of high fevers, headaches, myalgias, malaise, and a flu-like illness 3-12 days after tick bite; rash (80-90% of patients, initially maculopapular, then petechial, classically involving the palms and soles). Predisposing factors: tick exposure (April through September), pet owners, animal handlers, and outdoor activities. Commonest geographic location of infection: rural. Confirmatory serology via IFA. PCR with blood or skin biopsy: sensitive and specific but not widely available. General Considerations RMSF is caused by Rickettsia rickettsii and is an acute tick-borne illness occurring during seasonal tick activity. The disease is characterized by acute onset of fever, headache, and a rash of the extremities spreading …

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Ehrlichia Infection (Ehrlichiosis)

Essentials of Diagnosis Key symptoms and signs: abrupt onset of high fever, headache, myalgias, chills 8-9 days after tick bite; rash (36% of human monocytic ehrlichiosis [HME] patients; only 2% of human granulocytic ehrlichiosis [HGE] patients); central nervous system involvement (20-25% of patients). Predisposing factors: tick and rural exposure (April through September). Presentation: most present as flu-like illness. Key laboratory features: thrombocytopenia, leukopenia, and elevated liver transaminases. Diagnosis: confirmed by a fourfold or greater rise in titers with an IFA. General Considerations Human ehrlichiosis was first recognized in the United States in 1986 as a life threatening tick-borne illness similar to Rocky Mountain spotted fever (RMSF), but with a much lower …

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Coxiella, Ehrlichia, & Rickettsia

Coxiella, Ehrlichia, and Rickettsia spp. are small, obligate intracellular bacteria that usually cause disease when they accidentally encounter a human host. Once inside a host cell, Coxiella and Ehrlichia spp. remain within a vacuole where they progress through distinct developmental stages; in contrast, the Rickettsia spp. escape the endocytic vacuole and replicate within the host cell cytoplasm. Ehrlichia and Rickettsia spp. are transmitted by arthropod vectors. COXIELLA BURNETII INFECTION (Q FEVER) Essentials of Diagnosis Acute Infection Key symptoms and signs: fever, severe headache, myalgias, arthralgias, retrobulbar pain, cough; possible pneumonitis and hepatitis on examination. Predisposing factors: occupation as a dairy farmer, abattoir worker, or veterinarian; exposure to parturient or newborn animals, …

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Chlamydia

General Considerations Chlamydia trachomatis, Chlamydia psittaci, and Chlamydia pneumoniae are among the most prevalent microbial pathogens in humans worldwide. C trachomatis is responsible for a variety of sexually transmitted disease (STD) syndromes in both sexes. In addition, certain serotypes of C trachomatis are responsible for trachoma, the most common infectious cause of blindness in humans. C psittaci is a zoonotic pathogen associated with atypical pneumonia. C pneumoniae infects approximately one-half of the world’s human population and is a cause of upper and lower respiratory tract disease. It has also been associated with atherosclerotic cardiovascular disease. A. Epidemiology. In the United States, genital infections by C trachomatis serovars D through K occur …

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Chlamydia Psittaci Infections

Essentials of Diagnosis History of contact with birds. Positive C psittaci-specific microimmunofluorescence serologies. Positive complement fixation titers (not species specific). Clinical Findings A. Signs and Symptoms. Pneumonia, pericarditis, myocarditis, and endocarditis have been attributed to C psittaci infection (psittacosis or ornithosis) (Box 5). The incubation period for the pneumonia is usually 1-2 weeks. Its onset is gradual with body temperature increasing over a period of 5-7 days; however, there are cases in which the onset is sudden with rigors and temperatures as high as 104 °F. Headache is a salient and important symptom; it can be severe and incapacitating. Cough is usually nonproductive and hacking; however, on occasion a mucoid sputum …

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Chlamydia Trachomatis Infections

Essentials of Diagnosis Typical intracytoplasmic inclusions in Giemsa-stained cell scrapings from the conjunctiva. Ligase chain reaction (LCR) or polymerase chain reaction (PCR) in first-void urine. Positive culture in McCoy or HeLa cells of body fluids or secretions. Positive microimmunofluorescence serology for suspected cases of lymphogranuloma venereum and infants with pneumonia. Complement fixation titer of 1:64 or greater in patients with presumed lymphogranuloma venereum. Clinical Syndromes C trachomatis is associated with urethritis, proctitis, conjunctivitis, and arthritis in women and men; epididymitis in men; and mucopurulent cervicitis (MPC), acute salpingitis, bartholinitis, and the Fitz-Hugh and Curtis syndrome in women (Box 1). C trachomatis and Neisseria gonorrhoeae (see site) coinfections are common in women …

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