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F C Tenover

Publications and source records attributed to F C Tenover.

At least 37 records · Page 2Linked to original sources
PubMed2001

Characterization of clinical isolates of Klebsiella pneumoniae from 19 laboratories using the National Committee for Clinical Laboratory Standards extended-spectrum beta-lactamase detection methods.

Extended-spectrum beta-lactamases (ESBLs) are enzymes found in gram-negative bacilli that mediate resistance to extended-spectrum cephalosporins and aztreonam. In 1999, the National Committee for Clinical Laboratory Standards (NCCLS) published methods for screening and confirming the presence of ESBLs in Klebsiella pneumoniae, Klebsiella oxytoca, and Escherichia coli. To evaluate the confirmation protocol, we tested 139 isolates of K. pneumoniae that were sent to Project ICARE (Intensive Care Antimicrobial Resistance Epidemiology) from 19 hospitals in 11 U.S. states. Each isolate met the NCCLS screening criteria for potential ESBL producers (ceftazidime [CAZ] or cefotaxime [CTX] MICs were > or =2 microg/ml for all isolates). Initially, 117 (84%) isolates demonstrated a clavulanic acid (CA) effect by disk diffusion (i.e., an increase in CAZ or CTX zone diameters of > or =5 mm in the presence of CA), and 114 (82%) demonstrated a CA effect by broth microdilution (reduction of CAZ or CTX MICs by > or =3 dilutions). For five isolates, a CA effect could not be determined initially by broth microdilution because of off-scale CAZ results. However, a CA effect was observed in two of these isolates by testing cefepime and cefepime plus CA. The cefoxitin MICs for 23 isolates that failed to show a CA effect by broth microdilution were > or =32 microg/ml, suggesting either the presence of an AmpC-type beta-lactamase or porin changes that could mask a CA effect. By isoelectric focusing (IEF), 7 of the 23 isolates contained a beta-lactamase with a pI of > or =8.3 suggestive of an AmpC-type beta-lactamase; 6 of the 7 isolates were shown by PCR to contain both ampC-type and bla(OXA) genes. The IEF profiles of the remaining 16 isolates showed a variety of beta-lactamase bands, all of which had pIs of < or =7.5. All 16 isolates were negative by PCR with multiple primer sets for ampC-type, bla(OXA), and bla(CTX-M) genes. In summary, 83.5% of the K. pneumoniae isolates that were identified initially as presumptive ESBL producers were positive for a CA effect, while 5.0% contained beta-lactamases that likely masked the CA effect. The remaining 11.5% of the isolates studied contained beta-lactamases that did not demonstrate a CA effect. An algorithm based on phenotypic analyses is suggested for evaluation of such isolates.

Algorithms↗
PubMed2000

Emergence of domestically acquired ceftriaxone-resistant Salmonella infections associated with AmpC beta-lactamase.

CONTEXT: Ceftriaxone, an expanded-spectrum cephalosporin, is an antimicrobial agent commonly used to treat severe Salmonella infections, especially in children. Ceftriaxone-resistant Salmonella infections have recently been reported in the United States, but the extent of the problem is unknown. OBJECTIVES: To summarize national surveillance data for ceftriaxone-resistant Salmonella infections in the United States and to describe mechanisms of resistance. DESIGN AND SETTING: Case series and laboratory evaluation of human isolates submitted to the Centers for Disease Control and Prevention from 17 state and community health departments participating in the National Antimicrobial Resistance Monitoring System (NARMS) for enteric bacteria between 1996 and 1998. PATIENTS: Patients with ceftriaxone-resistant Salmonella infections between 1996 and 1998 were interviewed and isolates with decreased ceftriaxone susceptibility were further characterized. MAIN OUTCOME MEASURES: Exposures and illness outcomes, mechanisms of resistance. RESULTS: The prevalence of ceftriaxone-resistant Salmonella was 0.1% (1 of 1326) in 1996, 0.4% (5 of 1301) in 1997, and 0.5% (7 of 1466) in 1998. Ten (77%) of the 13 patients with ceftriaxone-resistant infections were aged 18 years or younger. The patients lived in 8 states (California, Colorado, Kansas, Massachusetts, Maryland, Minnesota, New York, and Oregon). Nine (82%) of 11 patients interviewed did not take antimicrobial agents and 10 (91%) did not travel outside the United States before illness onset. Twelve of the 15 Salmonella isolates with ceftriaxone minimum inhibitory concentrations of 16 microg/mL or higher were serotype Typhimurium but these isolates had different pulsed-field gel electrophoresis patterns. Thirteen of these 15 isolates collected between 1996 and 1998 were positive for a 631-base pair polymerase chain reaction product obtained by using primers specific for the ampC gene of Citrobacter freundii. CONCLUSIONS: Domestically acquired ceftriaxone-resistant Salmonella has emerged in the United States. Most ceftriaxone-resistant Salmonella isolates had similar AmpC plasmid-mediated resistance.

Adolescent↗
PubMed2000

Ability of laboratories to detect emerging antimicrobial resistance in nosocomial pathogens: a survey of project ICARE laboratories.

A proficiency testing project was conducted among 48 microbiology laboratories participating in Project ICARE (Intensive Care Antimicrobial Resistance Epidemiology). All laboratories correctly identified the Staphylococcus aureus challenge strain as oxacillin- resistant and an Enterococcus faecium strain as vancomycin-resistant. Thirty-one (97%) of 32 laboratories correctly reported the Streptococcus pneumoniae strain as erythromycin-resistant. All laboratories testing the Pseudomonas aeruginosa strain against ciprofloxacin or ofloxacin correctly reported the organism as resistant. Of 40 laboratories, 30 (75%) correctly reported resistant MICs or zone sizes for the imipenem- and meropenem-resistant Serratia marcescens. For the extended-spectrum beta-lactamase (ESBL)-producing strain of Klebsiella pneumoniae, 18 (42%) of 43 laboratories testing ceftazidime correctly reported ceftazidime MICs in the resistant range. These results suggest that current testing generally produces accurate results, although some laboratories have difficulty detecting resistance to carbapenems and extended-spectrum cephalosporins. This highlights the need for monitoring how well susceptibility test systems in clinical laboratories detect emerging resistance.

Aminoglycosides↗
PubMed2000

Activities of clinafloxacin, gatifloxacin, gemifloxacin, and trovafloxacin against recent clinical isolates of levofloxacin-resistant Streptococcus pneumoniae.

The activities of two investigational fluoroquinolones and three fluoroquinolones that are currently marketed were determined for 182 clinical isolates of Streptococcus pneumoniae. The collection included 57 pneumococcal isolates resistant to levofloxacin (MIC >/= 8 microg/ml) recovered from patients in North America and Europe. All isolates were tested with clinafloxacin, gatifloxacin, gemifloxacin, levofloxacin, and trovafloxacin by the National Committee for Clinical Laboratory Standards broth microdilution and disk diffusion susceptibility test methods. Gemifloxacin demonstrated the greatest activity on a per gram basis, followed by clinafloxacin, trovafloxacin, gatifloxacin, and levofloxacin. Scatterplots of the MICs and disk diffusion zone sizes revealed a well-defined separation of levofloxacin-resistant and -susceptible strains when the isolates were tested against clinafloxacin and gatifloxacin. DNA sequence analyses of the quinolone resistance-determining regions of gyrA, gyrB, parC, and parE from 21 of the levofloxacin-resistant strains identified eight different patterns of amino acid changes. Mutations among the four loci had the least effect on the MICs of gemifloxacin and clinafloxacin, while the MICs of gatifloxacin and trovafloxacin increased by up to six doubling dilutions. These data indicate that the newer fluoroquinolones have greater activities than levofloxacin against pneumococci with mutations in the DNA gyrase or topoisomerase IV genes. Depending upon pharmacokinetics and safety, the greater potency of these agents could provide improved clinical efficacy against levofloxacin-resistant pneumococcal strains.

Anti-Bacterial Agents↗
PubMed2000

Characterization of the extended-spectrum beta-lactamase reference strain, Klebsiella pneumoniae K6 (ATCC 700603), which produces the novel enzyme SHV-18.

Klebsiella pneumoniae K6 (ATCC 700603), a clinical isolate, is resistant to ceftazidime and other oxyimino-beta-lactams. A consistent reduction in the MICs of oxyimino-beta-lactams by at least 3 twofold dilutions in the presence of clavulanic acid confirmed the utility of K. pneumoniae K6 as a quality control strain for extended-spectrum beta-lactamase (ESBL) detection. Isoelectric-focusing analysis of crude lysates of K6 demonstrated a single beta-lactamase with a pI of 7.8 and a substrate profile showing preferential hydrolysis of cefotaxime compared to ceftazidime. PCR analysis of total bacterial DNA from K6 identified the presence of a bla(SHV) gene. K6 contained two large plasmids with molecular sizes of approximately 160 and 80 kb. Hybridization of plasmid DNA with a bla(SHV)-specific probe indicated that a bla(SHV) gene was encoded on the 80-kb plasmid, which was shown to transfer resistance to ceftazidime in conjugal mating experiments with Escherichia coli HB101. DNA sequencing of this bla(SHV)-related gene revealed that it differs from bla(SHV-1) at nine nucleotides, five of which resulted in amino acid substitutions: Ile to Phe at position 8, Arg to Ser at position 43, Gly to Ala at position 238, and Glu to Lys at position 240. In addition to the production of this novel ESBL, designated SHV-18, analysis of the outer membrane proteins of K6 revealed the loss of the OmpK35 and OmpK37 porins.

Amino Acid Sequence↗
PubMed2000

Multicenter evaluation of epidemiological typing of methicillin-resistant Staphylococcus aureus strains by repetitive-element PCR analysis. The European Study Group on Epidemiological Markers of the ESCMID.

Rapid and efficient epidemiologic typing systems would be useful to monitor transmission of methicillin-resistant Staphylococcus aureus (MRSA) at both local and interregional levels. To evaluate the intralaboratory performance and interlaboratory reproducibility of three recently developed repeat-element PCR (rep-PCR) methods for the typing of MRSA, 50 MRSA strains characterized by pulsed-field gel electrophoresis (PFGE) (SmaI) analysis and epidemiological data were blindly typed by inter-IS256, 16S-23S ribosomal DNA (rDNA), and MP3 PCR in 12 laboratories in eight countries using standard reagents and protocols. Performance of typing was defined by reproducibility (R), discriminatory power (D), and agreement with PFGE analysis. Interlaboratory reproducibility of pattern and type classification was assessed visually and using gel analysis software. Each typing method showed a different performance level in each center. In the center performing best with each method, inter-IS256 PCR typing achieved R = 100% and D = 100%; 16S-23S rDNA PCR, R = 100% and D = 82%; and MP3 PCR, R = 80% and D = 83%. Concordance between rep-PCR type and PFGE type ranged by center: 70 to 90% for inter-IS256 PCR, 44 to 57% for 16S-23S rDNA PCR, and 53 to 54% for MP3 PCR analysis. In conclusion, the performance of inter-IS256 PCR typing was similar to that of PFGE analysis in some but not all centers, whereas other rep-PCR protocols showed lower discrimination and intralaboratory reproducibility. None of these assays, however, was sufficiently reproducible for interlaboratory exchange of data.

Bacterial Typing Techniques↗
PubMed2000

A simplified method for testing Bordetella pertussis for resistance to erythromycin and other antimicrobial agents.

Present methods of antimicrobial susceptibility testing of Bordetella pertussis are time consuming and require specialized media that are not commercially available. We tested 52 isolates of B. pertussis for resistance to erythromycin, trimethoprim-sulfamethoxazole, chloramphenicol, and rifampin by agar dilution with Bordet-Gengou agar (BGA) containing 20% horse blood (reference method), Etest using BGA and Regan-Lowe agar without cephalexin (RL-C), and disk diffusion using BGA and RL-C. The organisms tested included four erythromycin-resistant isolates of B. pertussis from a single patient, a second erythromycin-resistant strain of B. pertussis from an unrelated patient in another state, and 47 nasopharyngeal surveillance isolates of B. pertussis from children in the western United States. The results of agar dilution testing using direct inoculation of the organisms suspended in Mueller-Hinton broth were within +/-1 dilution of those obtained after overnight passage of the inoculum in Stainer-Scholte medium, which is the traditional method of testing B. pertussis. The Etest method produced MICs similar to those of the agar dilution reference method for three of the four antimicrobial agents tested; the trimethoprim-sulfamethoxazole results were lower with Etest, particularly when the direct suspension method was used. Most of the Etest MICs, except for that of erythromycin, were on scale. Disk diffusion testing using RL-C medium was helpful in identifying the erythromycin-resistant strains, which produced no zone of inhibition around the disk; susceptible isolates produced zones of at least 42 mm. Thus, the antimicrobial susceptibility testing of B. pertussis can be simplified by using the Etest or disk diffusion on RL-C to screen for erythromycin-resistant isolates of B. pertussis.

Animals↗
PubMed2000

Evaluation of the PASCO strep plus broth microdilution antimicrobial susceptibility panels for testing Streptococcus pneumoniae and other Streptococcal species.

Antimicrobial resistance continues to increase worldwide among isolates of Streptococcus pneumoniae and other species of streptococci. Increasing rates of penicillin resistance, particularly in viridans group streptococci, and resistance to multiple classes of antimicrobial agents, including beta-lactams, macrolides, and fluoroquinolones, in pneumococci have increased the importance of having accurate antimicrobial susceptibility testing results for guiding therapy. One commercial method of assessing resistance in streptococci is the PASCO Strep Plus panel. This broth microdilution-based method has recently been expanded to include a variety of newer antimicrobial agents. Therefore, we compared the results of the new PASCO Strep Plus panels for 26 antimicrobial agents against the results generated using the National Committee for Clinical Laboratory Standards (NCCLS) broth microdilution reference method for 75 pneumococci and 68 other streptococcal isolates. Only 4 (0.2%) very major errors (all with pneumococci and each with a different antimicrobial agent) were observed. There were 5 (0.3%) major errors observed with pneumococci (each with a different antimicrobial agent), but only 1 major error with nonpneumococcal streptococci. All of the very major and major errors resolved on retesting. Of the 65 (3.9%) and 17 (1.6%) minor errors observed with pneumococci and other streptococci, respectively, all were within 1 dilution of the broth microdilution reference MIC result. Thus, the PASCO Strep Plus panel has comparable accuracy to the NCCLS broth microdilution reference method.

Anti-Bacterial Agents↗
PubMed2000

A 5' nuclease PCR (TaqMan) high-throughput assay for detection of the mecA gene in staphylococci.

In an effort to find a rapid, efficient, and reliable method of screening large numbers of bacterial isolates for specific antimicrobial resistance genes, we compared conventional PCR results to the results generated using the TaqMan 5' nuclease PCR kit in conjunction with an ABI Prism 7700 Sequence Detector for detecting the mecA gene in various species of staphylococci. DNA was extracted using two techniques. The first used a high-salt extraction method suitable for conventional PCR but resulted in a 7.2% rate of PCR inhibition with the TaqMan technique. PCR inhibition could be overcome by diluting samples 1:5 prior to testing. The second method used the Qiagen QIAamp Tissue Kit; no instances of PCR inhibition were encountered with this method. A total of 197 (96%) of the 206 samples with no inhibition showed agreement between the two methods. Eight of the nine disagreements were likely the result of low-level DNA cross contamination caused by frequent specimen handling. Target DNA in all eight of these samples was first detected in the initial tests only after >30 PCR cycles, and all were negative upon repeat testing even after 40 PCR cycles using freshly extracted DNA. Among those positive samples in agreement, target DNA was invariably detected before 30 PCR cycles. The TaqMan assay eliminated the need to load, run, stain, and read agarose gels and provided the advantage of instant detection of PCR product by laser-activated fluorescence. Thus, final results were obtained 2 h after PCR was initiated, as opposed to a requirement of 2 days to examine 96 samples by agarose gel electrophoresis.

Bacterial Proteins↗
PubMed1999

Epidemics of diarrhea caused by a clindamycin-resistant strain of Clostridium difficile in four hospitals.

BACKGROUND: Large outbreaks of diarrhea caused by a newly recognized strain of Clostridium difficile occurred in four hospitals located in different parts of the United States between 1989 and 1992. Since frequent use of clindamycin was associated with the outbreak in one of the hospitals, we examined the resistance genes of the epidemic-strain isolates and studied the role of clindamycin use in these outbreaks. METHODS: Case-control studies were performed at three of the four hospitals to assess the relation of the use of clindamycin to C. difficile-associated diarrhea. All isolates of the epidemic strain and representative isolates of other strains identified during each outbreak were tested for susceptibility to clindamycin. Chromosomal DNA from these representative isolates was also analyzed by dot blot hybridization and amplification with the polymerase chain reaction (PCR) with the use of probes and primers from a previously described determinant of erythromycin resistance - the erythromycin ribosomal methylase B (ermB) gene - found in C. perfringens and C. difficile. RESULTS: In a stratified analysis of the case-control studies with pooling of the results according to the Mantel-Haenszel method, we found that the use of clindamycin was significantly increased among patients with diarrhea due to the epidemic strain of C. difficile, as compared with patients whose diarrhea was due to nonepidemic strains (pooled odds ratio, 4.35; 95 percent confidence interval, 2.02 to 9.38; P<0.001). Exposure to other types of antibiotics or hospitalization in a surgical ward was not significantly associated with the risk of C. difficile-associated diarrhea due to the epidemic strain. All epidemic-strain isolates were highly resistant to clindamycin (minimal inhibitory concentration, >256 microg per milliliter). DNA hybridization and PCR analysis showed that all these isolates had an ermB gene, which encodes a 23S ribosomal RNA methylase that mediates resistance to macrolide, lincosamide, and streptogramin antibiotics. Only 15 percent of the nonepidemic strains were resistant to clindamycin. CONCLUSIONS: A strain of C. difficile that is highly resistant to clindamycin was responsible for large outbreaks of diarrhea in four hospitals in different states. The use of clindamycin is a specific risk factor for diarrhea due to this strain. Resistance to clindamycin further increases the risk of C. difficile-associated diarrhea, an established complication of antimicrobial use.

Anti-Bacterial Agents↗
PubMed1999

Emergence of vancomycin resistance in Staphylococcus aureus. Glycopeptide-Intermediate Staphylococcus aureus Working Group.

BACKGROUND: Since the emergence of methicillin-resistant Staphylococcus aureus, the glycopeptide vancomycin has been the only uniformly effective treatment for staphylococcal infections. In 1997, two infections due to S. aureus with reduced susceptibility to vancomycin were identified in the United States. METHODS: We investigated the two patients with infections due to S. aureus with intermediate resistance to glycopeptides, as defined by a minimal inhibitory concentration of vancomycin of 8 to 16 microg per milliliter. To assess the carriage and transmission of these strains of S. aureus, we cultured samples from the patients and their contacts and evaluated the isolates. RESULTS: The first patient was a 59-year-old man in Michigan with diabetes mellitus and chronic renal failure. Peritonitis due to S. aureus with intermediate resistance to glycopeptides developed after 18 weeks of vancomycin treatment for recurrent methicillin-resistant S. aureus peritonitis associated with dialysis. The removal of the peritoneal catheter plus treatment with rifampin and trimethoprim-sulfamethoxazole eradicated the infection. The second patient was a 66-year-old man with diabetes in New Jersey. A bloodstream infection due to S. aureus with intermediate resistance to glycopeptides developed after 18 weeks of vancomycin treatment for recurrent methicillin-resistant S. aureus bacteremia. This infection was eradicated with vancomycin, gentamicin, and rifampin. Both patients died. The glycopeptide-intermediate S. aureus isolates differed by two bands on pulsed-field gel electrophoresis. On electron microscopy, the isolates from the infected patients had thicker extracellular matrixes than control methicillin-resistant S. aureus isolates. No carriage was documented among 177 contacts of the two patients. CONCLUSIONS: The emergence of S. aureus with intermediate resistance to glycopeptides emphasizes the importance of the prudent use of antibiotics, the laboratory capacity to identify resistant strains, and the use of infection-control precautions to prevent transmission.

Aged↗
PubMed1999

Implications of vancomycin-resistant Staphylococcus aureus.

Strains of Staphylococcus aureus with reduced susceptibility to glycopeptides have been reported from Japan (multiple strains), the United States (four strains), and Europe (France, the UK and Spain) and the Far East (Hong Kong and Korea). The isolates from the US, France, and strain Mu50 from Japan, demonstrate vancomycin MICs of 8 microg/mL by broth microdilution testing and appear to have developed from pre-existing methicillin-resistant S. aureus (MRSA) infections. The strain from the UK and other parts of Europe appears heteroresistant to vancomycin and has MIICs in the 1-2 microg/mL range. Many of the isolates with reduced susceptibility to glycopeptides have been associated with therapeutic failures with vancomycin. Although nosocomial spread of the glycopeptide-intermediate S. aureus (GISA) strains has not been observed in US hospitals or in Europe, spread of GISA strains has apparently occurred in Japan. Laboratory studies have indicated that the disk diffusion test, the Stoke's method, and several automated methods of antimicrobial susceptibility testing do not detect GISA strains. The requirement to choose from a relatively small number of acceptable techniques for screening may well influence the ability of laboratories to conduct surveillance for these organisms. Finally, the isolation of such strains in three geographically distinct regions suggests that this phenomenon will continue to occur worldwide.

Forecasting↗
PubMed1999

A cluster of VanD vancomycin-resistant Enterococcus faecium: molecular characterization and clinical epidemiology.

VanD-mediated glycopeptide resistance has been reported for an isolate of Enterococcus faecium, BM4339. Three clinical isolates of vancomycin-resistant E. faecium collected from 3 patients during a 6-week period in 1993 had agar dilution MICs of vancomycin and teicoplanin of 128 and 4 microg/mL, respectively. Polymerase chain reaction (PCR) using degenerate primers complementary to genes encoding d-Ala-d-X ligases yielded a 630-bp product that was similar to the published partial sequence of vanD. By use of inverse PCR, vanD, vanHD, and two partial flanking open-reading frames were sequenced. The deduced amino acid sequence of VanD showed 67% identity with VanA and VanB. vanD appeared to be located on the chromosome and was not transferable to other enterococci. The 3 isolates were indistinguishable by pulsed-field gel electrophoresis and differed from BM4339. No other isolates carrying vanD were found in a subset of 875 recent US isolates of vancomycin-resistant enterococci.

Amino Acid Sequence↗
PubMed1999

Reporting of vancomycin-resistant enterococci in Connecticut: implementation and validation of a state-based surveillance system.

OBJECTIVE: To assess state-based surveillance for isolation from a sterile site of vancomycin-resistant enterococci (VRE) in Connecticut. DESIGN: Clinical laboratory reporting (passive surveillance) of VRE isolates to the Connecticut Department of Public Health (CDPH) was followed by state-initiated validation, laboratory proficiency testing, and review of hospital demographic characteristics. SETTINGS: All 45 clinical laboratories and all 37 (36 for 1995 and 1996) acute-care hospitals in Connecticut were included in the study. MAIN OUTCOME MEASURES: The outcome measures included determination of the statewide incidence of VRE and the accuracy of passive reporting, determination of clinical laboratory proficiency in detecting VRE, and analysis of hospital characteristics that might be associated with an increased incidence of VRE. RESULTS: During 1994 through 1996, 29 (78%) of 37 hospital-affiliated clinical laboratories and 1 (11%) of 9 commercial or other laboratories in Connecticut reported to the CDPH the isolation of VRE from sterile sites; 158 isolates were reported for these 3 years. Based on verification, we discovered that these laboratories actually detected 58 VRE isolates in 1994, 104 in 1995, and 104 in 1996 (total, 266). The age-standardized incidence rate of VRE was 14.1 cases per million population in 1994 and 26.8 cases per million population for both 1995 and 1996. Laboratory proficiency testing revealed that high-level vancomycin resistance was identified accurately and that low- and moderate-level resistance was not detected. The incidence of VRE isolates was three times greater in hospitals with over 300 beds compared with categories of hospitals with fewer beds. Increases in the number of VRE isolates were at least twice as likely in hospitals located in areas with a higher population density, or with a residency program or trauma center in the hospital. CONCLUSIONS: Passive reporting of VRE isolates from sterile sites markedly underestimated the actual number of iso lates, as determined in a statewide reporting system. Statewide passive surveillance systems for routine or emerging pathogens must be validated and laboratory proficiency ensured if results are to be accurate and substantial underreporting is to be corrected.

Adolescent↗
PubMed1999

The emergence of decreased susceptibility to vancomycin in Staphylococcus epidermidis.

BACKGROUND: Coagulase-negative staphylococci (CNS) are the major cause of nosocomial bloodstream infection. Emergence of vancomycin resistance among CNS is a serious public health concern, because CNS usually are multidrug-resistant, and glycopeptide antibiotics, among which only vancomycin is available in the United States, are the only remaining effective therapy. In this report, we describe the first bloodstream infection in the United States associated with a Staphylococcus epidermidis strain with decreased susceptibility to vancomycin. METHODS: We reviewed the hospital's microbiology records for all CNS strains, reviewed the patient's medical and laboratory records, and obtained all available CNS isolates with decreased susceptibility to vancomycin. Blood cultures were processed and CNS isolates identified by using standard methods; antimicrobial susceptibility was determined by using minimum inhibitory concentration (MIC) and disk-diffusion methods. Nares cultures were obtained from exposed healthcare workers (HCWs) to identify possible colonization by CNS with decreased susceptibility to vancomycin. RESULTS: The bloodstream infection by an S. epidermidis strain with decreased susceptibility to vancomycin occurred in a 49-year-old woman with carcinoma. She had two blood cultures positive for CNS; both isolates were S. epidermidis. Although susceptible to vancomycin by the disk-diffusion method (16-17 mm), the isolates were intermediate by MIC (8-6 microg/mL). The patient had received an extended course of vancomycin therapy; she died of her underlying disease. No HCW was colonized by CNS with decreased susceptibility to vancomycin. CONCLUSIONS: This is the first report in the United States of bloodstream infection due to S. epidermidis with decreased susceptibility to vancomycin. Contact precautions likely played a role in preventing nosocomial transmission of this strain, and disk-diffusion methods may be inadequate to detect CNS with decreased susceptibility to vancomycin.

Anti-Bacterial Agents↗
PubMed1999

The prevalence of colonization with vancomycin-resistant Enterococcus at a Veterans' Affairs institution.

OBJECTIVE: To study vancomycin-resistant Enterococcus (VRE) prevalence, risk factors, and clustering among hospital inpatients. DESIGN: Rectal-swab prevalence culture survey conducted from February 5 to March 22, 1996. SETTING: The Veterans' Affairs Medical Center, Atlanta, Georgia. PATIENTS: Hospital (medical and surgical) inpatients. RESULTS: The overall VRE prevalence was 29% (42/147 patients). The VRE prevalence was 52% (38/73 patients) among patients who had received at least one of six specific antimicrobials during the preceding 120 days, compared with only 5% (4/74) among those who had not received the antimicrobials (relative risk, 9.6; P<.001). The longer the period (up to 120 days) during which antimicrobial use was studied, the more closely VRE status was predicted. Among 67 hospital patients in 28 multibed rooms, clustering of VRE among current roommates was not found. CONCLUSIONS: At this hospital with relatively high VRE prevalence, VRE colonization was related to antibiotic use but not to roommate VRE status. In hospitals with a similar VRE epidemiology, obtaining cultures from roommates of VRE-positive patients may not be as efficient a strategy for identifying VRE-colonized patients as obtaining screening cultures from patients who have received antimicrobials.

Aged↗
PubMed1999

Determinants of vancomycin use in adult intensive care units in 41 United States hospitals.

We analyzed data from a prospective observational cohort study that included 108 adult intensive care units (ICUs) in 41 United States hospitals. Use of vancomycin (defined daily doses per 1,000 patient-days), nosocomial infection rates, and proportion of all Staphylococcus aureus isolates resistant to methicillin (MRSA rate) were recorded from January 1996 through November 1997. The median rate of vancomycin use was lowest in coronary care ICUs and highest in general surgical ICUs. Prior approval before use of vancomycin was required in only 26 (24%) of the 108 ICUs. In a multivariate linear regression model, rates of MRSA, central line-associated bloodstream infection, and the type of ICU were independent predictors of vancomycin use. None of the vancomycin control practices was associated with lower rates of vancomycin use; however, it is important to recognize that this database was not designed to measure rates of inappropriate use. Vancomycin use is heavily determined by rates of endemic MRSA and central line-associated bloodstream infection. Efforts to reduce these rates through infection control activities should be included in hospitals' efforts to reduce vancomycin use.

Adult↗