Tags: Gentamicin

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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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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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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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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Pseudomonas Aeruginosa

Essentials of Diagnosis • Nosocomial acquisition. • Predisposing factors include immunosuppression (neutropenia, cystic fibrosis [CF], AIDS, corticosteroid use, diabetes mellitus); presence of a foreign body, prosthesis, or instrumentation; prolonged hospitalization and antibiotic use; intravenous drug use. • Most common infections include pneumonia, bacteremia, urinary tract infection, otitis media, skin and skin structure infections, including ecthyma gangrenosa. • Gram stain shows gram-negative bacilli; recovery of microorganism from culture of blood or other tissue. General Considerations A. Epidemiology. The genus Pseudomonas consists of a number of human pathogens, the most important of which is Pseudomonas aeruginosa. P aeruginosa is an opportunistic pathogen found widely in soil, water, and organic material, reflecting its limited …

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Infection in Patients With Aids

Paeruginosa infections may occur in patients with AIDS. Risk factors for infection include a CD4 count of < 100 cells/mL3, neutropenia or functional neutrophil defects, intravascular catheterization, hospitalization, and prior use of antibiotics including ciprofloxacin or trimethoprim-sulfamethoxazole. Many cases are community acquired. Bacteremia is common, and the lung or an intravenous catheter is the most frequent portal of entry. An impaired ability to mount immunotype-specific antibodies to Pseudomonas lipopolysaccharide antigen has been noted in HIV-positive individuals with bacteremia. Relapse is frequent, and mortality is high, 40%. Pneumonia is usually associated with cavitation and a high relapse rate. Bacterial sinusitis is an important and frequently undetected illness in HIV-positive individuals, and P …

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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 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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Streptococcus Dysgalactiae Subspp. Equisilimis & Streptococcus Zooepidemicus:Clinical Syndromes

1. PHARYNGITIS The symptoms of pharyngitis caused by these organisms mimic those of S pyogenes pharyngitis (Box 50-1; see also site). Poststreptococcal glomerulonephritis has been described following S dysgalactiae subspp. equisimilis and S zooepidemicus pharyngitis. Notably, however, no antistreptolysin O antibody response will be detected as these organisms do not produce streptolysin O. S dysgalactiae subspp. equisimilis pharyngitis has been associated with sterile reactive arthritis. Acute rheumatic fever, however, has not been described in association with S dysgalactiae subspp. equisimilis and S zooepidemicus pharyngitis. 2. SKIN & SOFT TISSUE INFECTIONS Cellulitis, wound infections, pyoderma, erysipelas, impetigo, and cutaneous ulcers can be caused by these organisms (see site). Breaches in skin integrity …

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Group B Streptococcus (S Agalactiae) Clinical Syndromes

1. EARLY-ONSET GROUP B STREPTOCOCCAL NEONATAL INFECTION Early-onset group B streptococcal neonatal infection has three major clinical expressions: bacteremia with no identifiable focus of infection, pneumonia, and meningitis (Box 1). Signs and symptoms of early-onset group B streptococcal neonatal infection include lethargy, poor feeding, jaundice, abnormal temperature, grunting respirations, pallor, and hypotension. In most infants with pneumonia, symptoms of respiratory distress are present at or within a few hours after birth. Signs of respiratory distress associated with pneumonia include apnea, grunting, tachypnea, and cyanosis. The radiographic findings in infants with pneumonia may be indistinguishable from those of hyaline membrane disease. Infants with meningitis have a clinical presentation that initially cannot be …

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