ABSTRACT
Two phenotypic methods, quantitative antibiogram analysis and colony morphology, were compared to pulsed-field gel electrophoresis (PFGE) for distinguishing the clonality of coagulase-negative Staphylococcus (CNS) species. The results of these three methods were correlated with the patients' clinical findings for 23 episodes in which CNS species were isolated from two blood culture bottles within a 24-h period. Quantitative antibiogram and colony morphology at 24 h correlated with PFGE typing in 21 (91%) and 20 (87%) episodes, respectively. All episodes associated with CNS strains with identical PFGE patterns had quantitative antibiogram similarity coefficients < 10, whereas most episodes associated with strains with different PFGE patterns had quantitative antibiogram similarity coefficients >or= 17. The CNS isolate pairs were less likely to be associated with infection if the strains had different PFGE types or a quantitative antibiogram similarity coefficient >or= 17. Clinical microbiology laboratories should consider use of the quantitative antibiogram similarity coefficient to aid clinicians in distinguishing infection-associated CNS blood isolates from contaminants.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bacteremia/microbiology , Blood/microbiology , Coagulase/metabolism , Staphylococcus/classification , Staphylococcus/drug effects , Adolescent , Adult , Aged , Aged, 80 and over , Bacterial Typing Techniques , Child , Child, Preschool , Culture Media , Female , Humans , Infant , Male , Microbial Sensitivity Tests , Middle Aged , Staphylococcal Infections/microbiology , Staphylococcus/enzymology , Staphylococcus/geneticsABSTRACT
From March 1997 through November 1997, 8 allogenic bone marrow transplant (BMT) patients developed Stenotrophomonas maltophilia bacteremia on the hematology service at UCLA Medical Center (Los Angeles). Five of these patients had undergone transplantation during the same hospitalization that S. maltophilia bacteremia was detected (case patients). Compared with 7 concurrently hospitalized allogenic BMT patients (control patients), the 5 case patients were more likely to have been hospitalized in room A (P=.045), to have severe neutropenia on the culture date (P=.028), to have a longer duration of severe neutropenia (P=.05), to have severe mucositis (P=. 028), and to have received total parenteral nutrition (P=.028). Pulsed-field gel electrophoresis revealed that 2 of 3 isolates from case patients hospitalized in room A were identical. In allogenic BMT patients, severe neutropenia and severe mucositis may promote infection with S. maltophilia by impairing host defenses.
