Bacteremia caused by nonhemolytic group B streptococci

Abstract

Case Report A 75-yr-old woman with a history of type 2 noninsulin-dependent diabetes and hepatic cirrhosis with previous acute episodes of encephalopathy was admitted to the hospital because of abdominal swelling, tenderness of several day’s duration, and nausea On physical examination, the patient was afebrile and had tender hepatomegaly, ascites, and jaundice with normal central nervous system findings. The white blood cell count was 8,100/mm3 (85% neutrophils, 12% lymphocytes, and 3% monocytes). Prythrocyte sedimentation rate was 102 mm at the first hour. Other hematologic studies, metabolic profile, and liver function tests showed increased serum amylase (2,832 U/L), hyperglycemia, and hyperbilirubinemia An ultrasonogmphic study was done and a clinical diagnosis of acute pancreatitis was confiied. Medical therapy was begun, and the disease was self-limited within 3 d after treatment was instituted On the fifth day after admission, the patient underwent gynecological exploration because of vaginal discomfort, and a sample of the purulent vaginal discharge was sent to microbiology laboratory for culture. On the sixth day, she suddenly developed fever (39”C), and three sets of blood cultures were obtained. Empiric treatment with cefotaxime (2 g tid i.v.) was begun, yet the patient remained febrile. The vaginal sample grew a pure culture of a gram-positive, nonhemolytic coccus subsequently identified as Sneptoc0ccus agalactiue (3). The same microorganism also grew in all three blood culture sets after overnight incubation (BacTAlert system, Organon Teknika). A Gram stain of the blood culture showed gram-positive cocci resembling streptococci. The organism grew on sheep blood agar at 37°C with 5% COZ as small, white, slightly convex, nonhemolytic colonies, and hemolysis was not detectable on lifting a colony from the agar. The isolate was catalase-negative, PYRand bile esculin-negative, bacitracin-resistant, and did not grow in the presence of 6.5% sodium chloride. In addition, positive reactions for voges-Proskauer and hippurate hydrolysis tests were obtained. Group B streptococcal antigen was demonstrated with the PhadeBact test system (Karo Bio Diagnostics, Sweden), and a biochemical profile consistent with group B streptococci was obtained with the API 20 Strep test (bioM&ieux, France). Serotyping of the isolate by agglutination with antisera to GBS serotypes I through V (Dako A/S, Denmark) produced agglutination with the type II antisera. Repeated subcultures of the isolate onto blood agar under aerobic and anaerobic conditions failed to produce beta hemolysis. No pigment production was seen when the isolate was cultured in Granada medium, a selective and differential pigmentenhancing culture medium (4).