ABSTRACT
BACKGROUND: Ventricular assist devices (VAD) are currently approved for use as a bridge for transplantation. Although reports have suggested acceptable rates of survival of patients with VAD, there is little information regarding the mechanism and etiology of bacteremia in these patients. METHODS: We prospectively followed patients who underwent VAD implantation and developed bacteremia during VAD support at the University of Pittsburgh Medical Center. Relapsing bacteremia was defined as at least two episodes of positive blood cultures with a genetically related organism on 2 different days. Species identification and susceptibility testing were performed on all isolates. Pulse field gel electrophoresis was performed on selected blood and VAD isolates. RESULTS: Between January 1998 and August 1999, 3 patients with VAD developed relapsing bacteremia, which was treated with full courses of antibiotic agents, 2 of whom also developed VAD endocarditis. All 3 patients had documented driveline or device pocket infections with these isolates. Consecutive blood and VAD isolates were found to be genetically related within each patient. CONCLUSIONS: These patients with bacteremia after VAD implantation had relapse due to the same strain, which may have originated from indolent driveline infection. Endovascular infection in this setting is difficult to eradicate with antibiotic agents and carries a high mortality. These patients should be considered to have priority for orthotopic heart transplantation.
Subject(s)
Bacteremia/etiology , Heart-Assist Devices , Postoperative Complications/etiology , Adult , Bacteremia/mortality , Bacteriological Techniques , Endocarditis, Bacterial/etiology , Endocarditis, Bacterial/mortality , Humans , Male , Middle Aged , Postoperative Complications/mortality , Prospective Studies , Recurrence , Risk Factors , Survival RateABSTRACT
A cluster (14 of 18) of Streptococcus pneumoniae serotype 23F isolates that were resistant to penicillin (PEN), cephalosporin, and macrolide was found in one day care center in Kaohsiung, Taiwan. We analyzed the 18 isolates by pulsed field gel electrophoresis (PFGE). All but one serotype 23F isolate demonstrated identical PFGE patterns, which were different from the established pattern of the internationally spread Spanish 23F clone. The three strains of serotype 19F also showed a uniform pattern. These data strongly suggest that two novel clones of PEN-, cephalosporin-, and macrolide-resistant S. pneumoniae serotypes 23F and 19F are present in Taiwan.
Subject(s)
Anti-Bacterial Agents/pharmacology , Cephalosporins/pharmacology , Streptococcus pneumoniae/drug effects , Streptococcus pneumoniae/genetics , Child Day Care Centers , Child, Preschool , Drug Resistance, Microbial/genetics , Electrophoresis, Gel, Pulsed-Field , Humans , Macrolides , Microbial Sensitivity Tests/methods , Nasopharynx/microbiology , Penicillins/pharmacology , Pneumococcal Infections/microbiology , Serotyping , Streptococcus pneumoniae/classificationABSTRACT
Few data are available on the molecular subtypes of all penicillin-nonsusceptible Streptococcus pneumoniae (PNSP) from a defined population base. Pulsed-field gel electrophoresis (PFGE), serotyping, and antibiotic susceptibility testing were performed for all available invasive PNSP isolates for which the penicillin (MIC) was > or =0.1 microg/ml from Baltimore, Md., during 1995-1996 (n = 143). The dendrogram analysis of PFGE patterns included 32 distinct clonal groups. Six major clonal groups included two-thirds of the PNSP strains. Major clonal groups 2, 3, 4, and 6 strains were genetically related to four previously described international clones and were all multidrug resistant. Major clonal group 3 was genetically related to the Tennessee(23F)-4 clone and contained all four strains for which the penicillin MIC was 8 microg/ml. Most of the clonal group 1 and 5 strains had intermediate susceptibility to penicillin and were rarely multidrug resistant. The latter clonal groups represent two previously undescribed penicillin-intermediate pneumococcal clones. Clonal group homogeneity was greater for serotype 9V, 19A, and 23F strains than for serotype 6A, 6B, 14, and 19F strains. The classification of PNSP strains into clonal groups is essential for future population-based epidemiologic studies of PNSP.
Subject(s)
Penicillin Resistance , Streptococcus pneumoniae/classification , Adolescent , Adult , Aged , Child , Child, Preschool , Drug Resistance, Multiple , Electrophoresis, Gel, Pulsed-Field , Female , Humans , Infant , Infant, Newborn , Male , Maryland , Microbial Sensitivity Tests , Middle Aged , Phenotype , Streptococcus pneumoniae/drug effectsABSTRACT
A variety of pulsed-field gel electrophoresis (PFGE) protocols for the molecular subtyping of Streptococcus pneumoniae have been reported; most are time-consuming and complex. We sought to modify reference PFGE protocols to reduce the time required while creating high-quality gels. Only protocol modifications that resulted in high-quality banding patterns were considered. The following protocol components were modified. Lysis enzymes (lysozyme, mutanolysin, and RNase A) were deleted in a stepwise fashion, and then the lysis buffer was deleted. Lysis and digestion were accomplished in a single step with EDTA and N-lauroyl sarcosine (ES; pH 8.5 to 9.3) incubation at 50 degrees C in the absence of proteinase K. All enzymes except the restriction enzyme were omitted. A minimum incubation time of 6 h was required to achieve high-quality gels. All of the reactions were performed within 9 h, and the total protocol time from lysis to gel completion was reduced from 3 days to only 36 h. Combining lysis and digestion into a single step resulted in a substantial reduction in the time required to perform PFGE for S. pneumoniae. The ES solution may have caused cell lysis by activating N-acetylmuramyl-L-alanine amidase, the pneumococcal autolysin.
