Serologic testing for Salmonella lacks overall sensitivity and specificity and varies with the stage of infection.[3, 24] Complete blood cell count Anemia is a result of blood loss and inflammation. The white blood cell (WBC) count in enteric or typhoid fever is often low. Leukocytosis is common in the first 10 days in children and may also result from bacteremia, localized infection, bowel perforation, or other extraintestinal complications. Reversible thrombocytopenia may occur. Liver function tests may be mildly elevated. Elevated alanine aminotransferase level (>70 IU/L) can be seen in enteric fever.[25] A reversible form of a mild disseminated intravascular coagulopathy (DIC) may occur. Cultures The diagnosis of Salmonella infection is based on isolation of the infecting organism. Stool culture results can take 3-7 days. Three to ten grams collected over several days are preferred.[21] Due to the time involved with stool culture detection, treatment decisions should be based on the patient’s presentation. Rapid testing technologies, such as polymerase chain reaction (PCR), have not yet been proven feasible.[26] Culture sensitivity decreases after the first week of illness and antibiotic therapy.[3, 24] Bone marrow evaluation is considered the criterion standard for enteric fever and has a sensitivity of 90% but is rarely performed. Bone marrow aspirates have approximately 10 times the concentration of viable organisms versus blood and continue to have high sensitivity with prior antimicrobial treatment and regardless of duration of disease.[23] Blood culture results in enteric fever are positive in 50-70% of cases and often considered practical first choice. PCR sensitivity on blood is 84.5% and is as high as 95% when performed in the first 5 days.[24] PCR evaluations on urine and feces are 69% and 47% sensitive, respectively.[24] Duodenal string culture is an additional option.[23] Three serially collected urine samples for suspected enteric fever patients have reported sensitivities of 92% and specificities of 71%.[23] Antibody assays are commonly used to detect nontyphoid Salmonella in veterinary and food sectors, but this has not extended to standardized testing in human salmonellosis.[27]
Posted on: Sun, 11 Aug 2013 20:37:17 +0000
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