Tags: tetracyclines

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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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), …

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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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C 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 …

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C 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) …

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Mycoplasma & Ureaplasma

Mycoplasma and Ureaplasma species (mycoplasmas) are ubiquitous in nature and are commonly found in plants, animals, and humans. These bacteria contain the smallest amount of double-stranded DNA that is capable of producing a free-living microorganism; they measure between 0.15 and 0.3 um in diameter and = 2 um in length. They are believed to have evolved from a putative common ancestor of the gram-positive bacteria by a process of genome reduction and adoption of a dependent, parasitic life style. Mycoplasma and Ureaplasma spp. lack a cell wall. Therefore, they cannot be visualized with the Gram stain and are not susceptible to antibiotics that act on cell wall synthesis (eg, penicillins and …

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M Pneumoniae Infection & Disease

M pneumoniae is an important cause of upper and lower respiratory infections in both adults and children. Extrapulmonary involvement, including dermatological, neurological, cardiac, musculoskeletal, and vasculitic involvement, has also been associated with M pneumoniae infection in humans. Essentials of Diagnosis • Community acquired pneumonia. • Extrapulmonary involvement is not infrequent. • Inflammatory cells on sputum Gram stain but no predominant bacterial type. • Coombs-positive hemolytic anemia. • Cold agglutinin titer of = 1:32. • Fourfold change in specific immunoglobulin G (IgG) or IgM titers. General Considerations A. Epidemiology. Infected humans are the only source of M pneumoniae organisms for transmission to new susceptible hosts. M pneumoniae is spread from one individual …

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Brucella, Francisella, Pasteurella, Yersinia, & Hacek

BRUCELLOSIS Essentials of Diagnosis • Suspected in patients with chronic fever of unknown etiology who have a history of occupational exposure or come from a high prevalence area. • Leukopenia. • Blood culture or bone marrow cultures on appropriate media. • Serum antibody titer = 1:160. • Polymerase chain reaction. General Considerations 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. A. Epidemiology. Brucellosis is transmitted …

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Plague

Essentials of Diagnosis • Suspected in patients living in or traveling from an endemic area who have acute onset of fever, prostration, and tender adenopathy. • Yersinia pestis may be recovered from blood cultures or cultures of an aspirate from buboes or sputum in the pneumonic form in 80%-100% of cases. • Gram stains of bubo aspirate or sputum demonstrate the characteristic bipolar “safety pin” gram-negative microorganisms. • Y pestis grows aerobically on most culture media after 48-72 h of incubation. General Considerations The genus Yersinia, named after Alexander Yersin (1863-1943), includes Y pestis, Y enterocolitica, and Y pseudotuberculosis. Y pestis is the cause of plague, a disease that has left …

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Tularemia

Essentials of Diagnosis • Suspected in patients with fever, lymphadenopathy, and skin lesions who have a history of animal exposure (including to wild animals, ticks, or deerflies) or are coming from a high prevalence area or in laboratory personnel who work with Francisella spp. • Blood culture or other biologic specimen cultures on appropriate culture media. • Serum antibody titer = 1:160 or a fourfold increase or decrease in titer. General Considerations 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 …

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