Tags: Vancomycin

Important Anaerobes

Essentials of Diagnosis • Foul odor of draining purulence. • Presence of gas in tissues. • No organism growth on aerobic culture media. • Infection localized in the proximity of mucosal surface. • Presence of septic thrombophlebitis. • Tissue necrosis and abscess formation. • Association with malignancies (especially intestinal). • Mixed organism morphologies on Gram stain. General Considerations A. Epidemiology and Ecology. Anaerobic bacteria are the predominant component of the normal microbial flora of the human body. The following sites harbor the vast majority of them: • Skin: Mostly gram-positive bacilli such as Propionibacterium acnes • Gastrointestinal tract: In the oral cavity Prevotella spp., Porphyromonas spp., Peptostreptococcus spp., microaerophillic streptococci, and …

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Toxin-Mediated Infections

1. TETANUS Tetanus is a disease of global incidence produced by the toxin of Clostridium tetani. The risk of acquiring it increases in people > 60 years of age and in neonates, especially in Third World countries where poor sanitary conditions predispose to umbilical stump contamination. Immunization campaigns have played a crucial role in bringing about the observed decreasing incidence in the United States. The pathogenesis of tetanus involves the absorption of preformed toxin, or, less commonly, invasion of toxin-producing organisms from contaminated wounds; it may complicate surgical wounds colonized with C tetani. Incubation periods vary depending on the portal of entry. The toxin tetanospasmin blocks the transmission of inhibitory neurons, …

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Haemophilus, Bordetella, & Branhamella Species

HAEMOPHILUS INFLUENZAE & OTHER HAEMOPHILUS SPECIES Essentials of Diagnosis • Haemophilus influenzae is generally acquired via the aerosol route or by direct contact with respiratory secretions. • The most common associated syndromes include otitis media, sinusitis, conjunctivitis, bronchitis, pneumonia, and, to a lesser extent, meningitis, epiglottitis, arthritis, and cellulitis. • Gram stain shows pleomorphic gram-negative coccobacilli. • In cases of meningitis, epiglottitis, arthritis, and cellulitis, organisms are typically recovered from blood, and type-b polysaccharide capsular material may be detected in the urine. • Organisms and type-b polysaccharide capsule may also be present in other appropriate sterile body fluids, such as cerebrospinal fluid (CSF) in meningitis and joint fluid in arthritis. General …

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Branhamella Catarrhalis: Clinical Syndromes

B catarrhalis causes bronchitis and pneumonia in patients with underlying lung disease, especially chronic obstructive pulmonary disease. It is also a rare cause of invasive disease, including meningitis, endocarditis, bacteremia without a focus, septic arthritis, and cellulitis. In addition, it is a recognized cause of acute conjunctivitis and is periodically mistaken as Neisseria gonorrhoeae in newborn infants with conjunctivitis. B catarrhalis occasionally colonizes the genital mucosa and has been reported as a cause of urethritis. Clinical Findings A. Signs and Symptoms. The signs and symptoms of B catarrhalis acute otitis media and sinusitis are indistinguishable from those present when acute otitis media and sinusitis are caused by other pathogens (Box 8). …

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Haemophilus Influenzae: Clinical Syndromes

H influenzae was first isolated during the 1892 influenza pandemic and was originally believed to be the causative agent of influenza. Although subsequent studies revealed the fallacy of this idea, H influenzae has proved to be a common cause of localized respiratory tract and systemic disease, including meningitis, epiglottitis, pneumonia, pyogenic arthritis, cellulitis, otitis media, and sinusitis, among others (Box 1). 1. MENINGITIS Meningitis is the most common and serious form of invasive H influenzae type-b disease. In the mid-1980s, before the introduction of effective vaccines, ~ 10,000-12,000 cases of H influenzae type-b meningitis occurred in the United States each year, and 95% of cases involved children < 5 years old. …

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Helicobacter Pylori

Essentials of Diagnosis • Positive serum immunoglobulin G usually indicates active infection. • Serology is generally not helpful for documentation of cure. • Urea breath test and stool antigen test are useful to document cure. • Acid suppression therapy decreases the sensitivity of the urea breath test. • Culture and susceptibility testing may be useful in refractory cases. General Considerations Pathologists have noted spiral bacteria in biopsies and autopsy specimens of gastric mucosa for over 100 years. Their significance was alternately debated and ignored until 1982, when Barry Marshall and Robin Warren cultivated the organism for the first time and suggested that it might be a cause of chronic gastritis and …

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Neisseria Gonorrhoeae & Neisseria Meningitidis

Neisseria gonorrhoeae was first described by Albert Neisser in 1879, in the ocular discharge and exudate from newborn infants with conjunctivitis. Descriptions of a condition resembling the disease gonorrhea can be found in the written record as early as 130 AD, when Galen created a descriptor for the malady by using the Greek words gonos (seed) and rhoea (flow) to characterize what was believed to be the morbid loss of semen. Neisseria meningitidis is thought to be responsible for epidemics in the Napoleonic and Persian armies in the early 1800s. The pathogen was first described in 1886 by Weichselbaum, who observed gram-negative diplococci in the cerebrospinal fluid (CSF) of a young …

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Gram-Positive Aerobic Bacilli

LISTERIA MONOCYTOGENES Essentials of Diagnosis • Incriminated foods include unpasteurized milk, soft cheeses, undercooked poultry, and unwashed raw vegetables. • Asymptomatic fecal and vaginal carriage can result in sporadic neonatal disease from transplacental and ascending routes of infection. • Incubation period for foodborne transmission is 21 days. • Organism causes disease especially in neonates, pregnant women, immunocompromised hosts, and elderly. • Organism is grown from blood, cerebrospinal fluid (CSF), meconium, gastric washings, placenta, amniotic fluid, and other infected sites. General Considerations A. Epidemiology. L monocytogenes is found in soil, fertilizer, sewage, and stream water; on plants; and in the intestinal tracts of many mammals. It is a foodborne pathogen that causes …

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Other Bacillus Species

General Considerations Bacillus species other than B anthracis are found in soil, decaying organic matter, and water, but they are rare causes of disease. Risk factors associated with Bacillus infection include the presence of intravascular catheters, intravenous drug use, sickle cell disease, and immunosuppression — particularly corticosteroid use, transplantation, AIDS, and neutropenia secondary to chemotherapy. The hardy growth characteristics of Bacillus spp. cause them to arise as common laboratory contaminants; however, they are also capable of causing severe invasive illness. B cereus and B subtilis are the most frequent Bacillus spp. to cause invasive infection. Pneumonia, meningoencephalitis, endocarditis (native and prosthetic valves), and intravascular catheter infection have been well described. High-grade …

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Other Gram-Positive Cocci

The following organisms are too rare to merit extensive discussion of clinical syndromes, diagnosis, and treatment (see Box 4). STREPTOCOCCUS INIAE S iniae has recently been described as a cause of cellulitis, bacteremia, endocarditis, meningitis, and septic arthritis associated with the preparation of the aquacultured fresh fish tilapia. LEUCONOSTOC SPECIES Leuconostoc spp. are gram-positive cocci or coccobacilli that grow in pairs and chains; Leuconostoc spp. may be morphologically mistaken for streptococci. They are vancomycin-resistant facultative anaerobes that are commonly found on plants and vegetables and less commonly in dairy products and wine. Leuconostoc spp. have been documented to cause bacteremias, intravenous line sepsis with localized exit site infection and/or bacteremia, meningitis, …

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