Tags: Sulfonamides

Pathogenic Amebas

ENTAMOEBA HISTOLYTICA & ENTAMOEBA DISPAR Essentials of Diagnosis Patient living in or having traveled to endemic area increases risk. Frequent loose stools with blood and mucus. Demonstration of cyst or trophozoite on stool wet mount or in biopsy specimen. Serology positive within 7-10 days of infection, may remain positive for years after infection resolved. Monoclonal antibodies and polymerase chain reaction emerging; may help differentiate E histolytica and E dispar. General Considerations A. Epidemiology. There are numerous distinct species of ameba within the genus Entamoeba, and the majority of these do not cause disease in humans. E histolytica is a pathogenic species that is capable of causing disease, such as colitis or …

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Toxoplasma Gondii

General Considerations A. Epidemiology. Toxoplasma gondii infection, or toxoplasmosis, is a zoonosis (the definitive hosts are members of the cat family). The two most common routes of infection in humans are by oral ingestion of the parasite and by transplacental (congenital) transmission to the fetus. Ingestion of undercooked or raw meat that contains cysts or of water or food contaminated with oocysts results in acute infection. In humans, the prevalence of toxoplasmosis increases with age. There are also considerable geographic differences in prevalence rates (eg, 10% in Palo Alto, CA; 15% in Boston, MA; 30% in Birmingham, AL; 70% in France; = 90% in El Salvador). Differences in the epidemiology of …

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Toxoplasma Gondii: Treatment

A. Infection in Immunocompetent Adults and Children. Immunocompetent adults and children with toxoplasmic lymphadenitis do not require treatment unless symptoms are severe or persistent. Infections acquired by laboratory accident or transfusion of blood products are potentially more severe, and these patients should always be treated. The combination of pyrimethamine, sulfadiazine, and folinic acid for 4-6 weeks is the most commonly used and recommended drug regimen (Box 2). Treatment should be administered for 2-4 weeks, followed by reassessment of the patient’s condition. The decision to treat active toxoplasmic chorioretinitis should be based on the results of an examination performed by an ophthalmologist. Pyrimethamine and sulfadiazine plus folinic acid are commonly used for …

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Paracoccidioidomycosis

Essentials of Diagnosis Patients usually immunocompetent. Patients in endemic areas with chronic pulmonary and mucotaneous lesions involving the mouth, nose, larynx, and face; regional or diffuse lymphadenopathy. Found in Latin America, from Mexico to Argentina. Dimorphic fungus: yeast form in tissue specimens and at 37 °C; mold form when grown at room temperature in the laboratory. Thick-walled yeast, 4-40 um, with multiple buds when seen in tissue specimens. Complement fixation or immunodiffusion. General Considerations Paracoccidioidomycosis is caused by Paracoccidioides brasiliensis. Also known as South American blastomycosis, it is the most prevalent systemic mycosis found in Central and South America and is the most common endemic mycosis in this area. A. Epidemiology. …

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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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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, …

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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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Penicillins: Organs and Systems

Respiratory Bronchospasm may be a consequence of penicillin allergy. Acute severe dyspnea with cyanosis has also been observed without symptoms of bronchial obstruction or pulmonary edema. Specific mechanisms for such cases have yet to be identified. Allergic pneumonitis and transient eosinophilic pulmonary infiltrate (Loeffler’s syndrome) are rare. These syndromes have also been observed with penicillin hypersensitivity. In one case, an alveolar allergic reaction, probably due to ampicillin, showed features of an adult respiratory distress syndrome. Nervous system High doses of penicillins, in the order of several million units/day of penicillin G, can produce myoclonic jerks, hyper-reflexia, seizures, or coma. Drowsiness and hallucinations can occur occasionally. Such reactions are due to a …

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Penicillins: Organs and Systems: Hematologic

Since the days when chloramphenicol was more commonly used, it has been recognized that many antimicrobial drug are associated with severe blood dyscrasias, such as aplastic anemia, neutropenia, agranulocytosis, throm-bocytopenia, and hemolytic anemia. Information on this association has come predominantly from case series and hospital surveys (38^. Some evidence can be extracted from population-based studies that have focused on aplastic anemia and agranulocytosis and their association with many drugs, including antimicrobial drugs. The incidence rates of blood dyscrasias in the general population have been estimated in a cohort study with a nested case-control analysis, using data from a General Practice Research Database in Spain. The study population consisted of 822048 patients …

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