Tags: Ceftriaxone

Borrelia & Leptospira Species

BORRELIA SPECIES RELAPSING FEVER Essentials of Diagnosis The most common presentation is fever with rash, headache, shaking chills, myalgias, arthralgias, and — during the acute phase — hepatosplenomegaly. Louse-borne relapsing fever (LBRF) is epidemic, caused by B. recurrentis, and characterized by one or two relapses. Tick-borne relapsing fever (TBRF) is endemic, caused by several Borrelia species, and characterized by multiple clinical relapses. Organisms can be visualized in blood smears of febrile patients, unlike other spirochetal pathogens, using dark-field microscopy or Giemsa or Wright stains. Helical (3-10 spirals) spirochetes, 8-30 um × 0.3 um, motile (flagella). Weil-Felix reaction: Proteus OX-K agglutinin titers are elevated (this is more common in LBRF). General Considerations […]

Treponema Pallidum

Essentials of Diagnosis Spiral, motile, coil-shaped, elongated (0.10 um × 5-20 um) spirochete. No reliable method for sustained in vitro cultivation. Direct detection with darkfield microscopy or immunofluorescent antibody in early syphilis. Nontreponemal antibody tests (rapid plasma reagin, Venereal Disease Research Laboratory [VDRL]) for screening, treatment follow-up. Treponema-specific antibody tests (fluorescent treponemal antibody test, microhemagglutination-T pallidum test) for confirmation. Cerebrospinal fluid (CSF) lymphocytosis, elevated CSF protein, or reactive CSF VDRL test suggests neurosyphilis. PCR, DNA probes, and immunoblotting techniques promising in congenital syphilis, early syphilis, or neurosyphilis. All patients with T pallidum infection should be tested for HIV coinfection and vice versa. General Considerations The term syphilis was first used in […]

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. Epidemiology Brucellosis is transmitted to humans by either direct contact […]

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 Considerations Epidemiology Before 1990, strains […]

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). 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. Nowadays, […]

Enteritis Caused by Escherichia coli & Shigella & Salmonella Species

Essentials of Diagnosis Enteritis: diarrhea, which may be watery, bloody, or dysenteric; abdominal pain; and fever and/or; Systemic disease: highly variable presentations that may include enteric fever, hemolytic uremic syndrome, or bacteremia with infectious foci in distant sites. History of exposure, possibly in known endemic areas or associated with an outbreak, through the ingestion of unclean water, unpasteurized juice or milk, undercooked meats, or other possibly contaminated food. Microbiologic isolation and identification of enteric pathogens or molecular detection. General Considerations The Enterobacteriaceae are a diverse family of bacteria that, in nature, exist in soil, on plant material, and in the intestines of humans and other animals. Another ecological niche in which […]

Enteric Fever

Clinical Findings Signs and Symptoms Patients are asymptomatic during the incubation phase. Early in the course of disease, patients may experience diarrhea or constipation. Patients then develop a variety of nonspecific symptoms, such as fever, chills, weakness, malaise, myalgia, and cough. Signs, that are not always present, such as rose spots, paroxysmal bradycardia in sharp contrast to the clinical presentation and elevated temperature, and hepatosplenomegaly are clues to the diagnosis. Profound mental status changes and picking at bed clothing, termed typhoid psychosis, may develop in some patients with enteric fever. The middle phase of disease is the time of maximal symptomatology. If complications do not intervene (see below), patients begin to […]

Neisseria Meningitidis

Essentials of Diagnosis Transmission in crowded or closed populations. Meningitis most common, but bacteremia, pneumonia, and other syndromes can occur in absence of meningitis. Disease often associated with petecchial or purpuric rash, which may involve palms and soles. Neutrophil-predominant cell profile in CSF, with low-glucose and high-protein concentrations. Gram-negative diplococci inside neutrophils on stained smears of CSF and aspirated skin lesions. Fastidious organism requires special media and growth conditions. Blood and CSF most useful specimens for recovery of organism. Improved sensitivity of detection with PCR in CSF, but not widely available. General Considerations Epidemiology N meningitidis is found only in humans and is a member of the normal oropharyngeal flora in […]

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 […]

Other Gram-Positive Cocci

VIRIDANS GROUP STREPTOCOCCI, INCLUDING ABIOTROPHIA DEFECTIVA & ABIOTROPHIA ADJACENS Essentials of Diagnosis Facultatively anaerobic gram-positive cocci, catalase negative, coagulase negative. a or ß hemolytic on blood agar. Abiotrophia defectiva and Abiotrophia adjacens require pyridoxal or thiol group supplementation. Streptococcus milleri group organisms often exhibit Lancefield antigens A, C, F, or G and often have a butterscotch odor. General Considerations Epidemiology Viridans streptococci are part of the normal microbial flora of humans and animals and are indigenous to the upper respiratory tract, the female genital tract, all regions of the gastrointestinal tract, and, most significantly, the oral cavity. Clinically significant species that are currently recognized as belonging to the viridans group of […]