Tags: cephalosporins

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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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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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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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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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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