Tags: Rifampin

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. 1. ACUTE GIARDIASIS Clinical Findings A. Signs and Symptoms. After ingestion of cysts, an incubation period of 3-20 days exists before symptom onset. At the time of presentation, patients …

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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 …

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Cryptococcus Neoformans

Essentials of Diagnosis • Routine laboratory tests often normal. • One-third of patients are afebrile. • Definitive diagnosis made by fungal culture maintained at 37°C for 6 weeks. • Cryptococcal antigen 95% sensitive in CNS infection in centrifuged CSF. • India ink examination positive in only 50% of meningoencephalitis cases. • CSF lymphocytes often low in CNS infection, especially in AIDS patients. • Cryptococcal antigen most sensitive detection method in serum. • Chest radiograph variable — multiple areas of infiltration in lower lobes most common in pulmonary disease. • Molecular detection by PCR might soon become laboratory standard. General Considerations A. Epidemiology and Ecology. Cryptococcus neoformans exists as two distinct varieties …

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Blastomyces Dermatitidis

Essentials of Diagnosis • Round thick-walled yeast with broad-based budding. • Dimorphic: mycelial in nature, yeast in tissue. • Associated with activities in proximity to waterways. • Associated with exposure to dust, eg excavation. • Endemic in states surrounding the Mississippi and Ohio Rivers. • Pyogranulomas on histopathological examination. • Acute or chronic infection of lung, skin, bone, or genitourinary tract. • Recovery of microorganism from culture of tissue. General Considerations A. Epidemiology. Blastomyces dermatitidis is an endemic fungus that causes acute and chronic infections in humans and other animals. It is found primarily in the south central, southeastern, and midwestern United States, especially in the states surrounding the Mississippi and …

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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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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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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 …

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Tuberculosis

Essentials of Diagnosis • The cardinal symptoms of tuberculosis (TB) are fatigue, weight loss, fever, and night sweats. • The most commonly infected populations include the homeless, institutionalized patients, and HIV-positive patients. • In most cases, a TB skin test (PPD) is positive. • To establish presence of infection, an acid-fast bacilli (AFB) smear demonstrates the acid-fast bacillus. • In primary pulmonary TB, an infiltrate in the lower lobes of the lung is usually seen on chest x-ray. In contrast, apical lung infiltrates are commonly seen in the reactivation of pulmonary TB. General Considerations Mycobacterium tuberculosis is still an important pathogen. Approximately one-third of the world’s population is infected with M …

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Tuberculosis: Clinical Syndromes

PULMONARY TUBERCULOSIS The most common syndrome in adults is pulmonary TB, which accounts for ~ 80% of cases of active disease. Clinical Findings A. Signs and Symptoms. Symptoms of infection consist of fatigue, weight loss, fever, night sweats, and a productive cough. Most children who are infected with TB usually have no symptoms. Early symptoms can also include hemoptysis, which also occurs later in the disease when there is significant necrosis of lung parenchyma or if previous cavitations erode into arterioles. Patients with subpleural parenchymal inflammation with pleural membrane involvement or with TB pleuritis without parenchymal disease can experience pleuritic chest pain. Severe shortness of breath is not common. However, extensive …

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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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