Tags: fluoroquinolones

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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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 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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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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Mycoplasma Pneumoniae Infection & Disease

Mycoplasma 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 to another by respiratory droplets produced …

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Actinomycetes

Actinomycetes are variably acid-fast, gram-positive bacilli that are sometimes filamentous and branched. Originally thought to be fungi due to their hyphae-like appearance, they are now recognized as bacteria based on their cell wall components, reproduction by fission without sporulation or budding, inhibition by antibacterial agents, and molecular phylogenetic analysis. The actinomycete chromosomes contain a high content of guanosine and cytosine. The actinomycetes include the genera Mycobacterium and Corynebacterium, which are discussed in site and site, respectively. The actinomycetes also include the genera Nocardia, Actinomyces, Rhodococcus, Tsukumurella, Gordona, Actinomadura, and Streptomyces, as well as the Whipple’s disease bacillus Tropheryma whippelii. Of these, members of the genus Nocardia are the most significant from …

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Nocardia

Essentials of Diagnosis Gram-positive, variably acid-fast, branching filaments with aerial hyphae. Colonies have characteristic chalky-white or cotton ball appearance. Suspect when chronic pulmonary disease is accompanied by CNS or skin lesions. No specific antibody or antigen detection tests. General Considerations A. Epidemiology. Nocardia spp. are strictly aerobic, ubiquitous soil-dwelling organisms that are largely responsible for the decomposition of organic plant material. Infection usually occurs via inhalation of these organisms in airborne dust particles, leading to pulmonary disease. However, infection can also be acquired via direct percutaneous inoculation by thorns, animal scratches, bites, surgical wounds, and intravenous catheters. Dissemination commonly occurs to the central nervous system (CNS), skin, and subcutaneous tissues. Nocardiosis …

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Other Mycobacteria

Essentials of Diagnosis Demonstration of the acid-fast bacillus. Infections more common in immunocompromised hosts. Infections mainly pulmonary or soft tissue. General Considerations 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. Most infections caused by atypical mycobacteria are skin and soft tissue abscesses, sometimes following pulmonary infection or implantation of prosthetic devices. There have been a few reports of epidemics of iatrogenic infection with atypical mycobacteria, associated with injection of contaminated materials. …

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Yersiniosis

Essentials of Diagnosis • Suspected in a child living in or traveling from a high-prevalence area who has fever, abdominal pain, and diarrhea followed by a reactive polyarthritis. • Yersinia spp. are recovered from cultures of specimens of stool, mesenteric lymph nodes, blood, or abscess material. • Inoculation of duplicate sets of cultures for incubation at 37 and 25 °C, respectively, enhances recovery of the microorganisms. General Considerations A. Epidemiology. 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 …

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