Blood-Modified Carbapenem Inactivation Method: a Phenotypic Method for Detecting Carbapenemase-Producing Enterobacteriaceae Directly from Positive Blood Culture Broths.

A variant of the modified carbapenem inactivation method (mCIM) was developed to detect carbapenemase activity directly from positive blood culture broths. The method, termed "Blood-mCIM," was evaluated using Bactec blood culture bottles (Becton, Dickinson and Company, Franklin Lakes, NJ) inoculated with 27 different carbapenemase-producing Enterobacteriaceae (CPE) isolates and 34 different non-CPE isolates. The assay was positive for all blood culture broths inoculated with CPE isolates and negative for all blood culture broths inoculated with non-CPE isolates, corresponding to a diagnostic sensitivity and specificity of 100%, respectively. This assay is inexpensive using "off the shelf" reagents, does not require centrifugation or mechanical lysis, and can be readily implemented in any clinical microbiology laboratory. The Blood-mCIM should facilitate expedient administration of antimicrobial therapy targeted toward CPE bloodstream infections and assist infection control and public health surveillance.

Epidemiologic trends in Clostridioides difficile isolate ribotypes in United States from 2011 to 2016.

BACKGROUND: Geographic and temporal trends in the distribution of PCR ribotypes for Clostridioides difficile associated diarrheal isolates obtained in the United States (US) are changing. As part of a US national surveillance program of C. difficile susceptibility to fidaxomicin, we quantified the distribution of PCR ribotypes of stool isolates collected from 2011 to 2016. METHODS: C. difficile isolates or C. difficile toxin + stools from patients with C. difficile infection (CDI) were submitted for testing to Tufts Medical Center from 6 geographically distinct medical centers. Following isolation and confirmation as C. difficile, approximately 35% of the isolates were randomly sampled, stratified by center, for PCR ribotyping by capillary gel electrophoresis. Toxin gene profiling was performed on all isolates. RESULTS: 939 isolates from a total of 2814 (33.4%) isolated over the 6 years were analyzed. Seventy unique ribotypes were observed, including 19 ribotypes observed 10 or more times. Sixteen ribotypes were not previously observed in our data base. Ribotype 027 declined by more than 60% over the 6 years of the survey from 35.3% to 13.1% (p < 0.001). Ribotype 106 was the most common in 2016, followed by 027 and 014-020. There were strong correlations between 027 and binary toxin with the 18 base pair deletion of tcdC and ribotype 078-126 had 100% concordance with the previously described tcdC 39 base pair deletion. CONCLUSIONS: The frequency of ribotypes in the US has changed with a marked decline in 027. Each of the geographical areas had variations which differed from each other, but collectively, these results suggest that the changing epidemiology of C. difficile in the US is consistent with what is being seen in Europe. Continued surveillance and monitoring of changes in ribotype distributions of C. difficile are warranted.

U.S.-Based National Surveillance for Fidaxomicin Susceptibility of Clostridioides difficile-Associated Diarrheal Isolates from 2013 to 2016.

In 2011, we initiated a sentinel surveillance network to assess changes in Clostridioides (formerly Clostridium) difficile antimicrobial susceptibility to fidaxomicin from 6 geographically dispersed medical centers in the United States. This report summarizes data from 2013 to 2016. C. difficile isolates or toxin-positive stools from patients were referred to a central laboratory. Antimicrobial susceptibility was determined by agar dilution. CLSI, EUCAST, or FDA breakpoints were used, where applicable. Toxin gene profiles were characterized by multiplex PCR on each isolate. A random sample of approximately 40% of isolates, stratified by institution and year, was typed by restriction endonuclease analysis (REA). Among 1,889 isolates from 2013 to 2016, the fidaxomicin MIC90 was 0.5 µg/ml; all isolates were inhibited at ≤1 µg/ml. There were decreases in metronidazole and vancomycin MICs over time. Clindamycin resistance remained unchanged (27.3%). An increase in imipenem resistance was observed. By 2015 to 2016, moxifloxacin resistance decreased in all centers. The proportion of BI isolates decreased from 25.5% in 2011 to 2012 to 12.8% in 2015 to 2016 (P < 0.001). The BI REA group correlated with moxifloxacin resistance (BI 84% resistant versus non-BI 12.5% resistant). Fidaxomicin MICs have not changed among C. difficile isolates of U.S. origin over 5 years post licensure. There has been an overall decrease in MICs for vancomycin, metronidazole, moxifloxacin, and rifampin and an increase in isolates resistant to imipenem. Moxifloxacin resistance remained high among the BI REA group, but the proportion of BI isolates has decreased. Continued geographic variations in REA groups and antimicrobial resistance persist.

EDTA-Modified Carbapenem Inactivation Method: a Phenotypic Method for Detecting Metallo-ß-Lactamase-Producing Enterobacteriaceae.

The increase in the prevalence and impact of infections caused by carbapenemase-producing Enterobacteriaceae is a global health concern. Therefore, rapid and accurate methods to detect these organisms in any clinical microbiology laboratory, including those in resource-limited settings, are essential to prevent and contain their spread. It is also important to differentiate between serine- and metal-dependent carbapenemases elaborated by carbapenemase-producing isolates for epidemiologic, infection control and prevention, and therapeutic purposes. Here, we describe the development and evaluation of the EDTA-modified carbapenem inactivation method (eCIM), an assay for discriminating between serine- and metal-dependent (i.e., metallo-ß-lactamases [MBLs]) carbapenemases when used in conjunction with the modified carbapenem inactivation method (mCIM). The eCIM had an overall sensitivity and specificity of 100% and was adopted by the Clinical and Laboratory Standards Institute as a method to use in combination with the mCIM to identify MBL-producing Enterobacteriaceae.

Trends in antimicrobial resistance among Bacteroides species and Parabacteroides species in the United States from 2010-2012 with comparison to 2008-2009.

The susceptibility trends for Bacteroides fragilis and related species against various antibiotics were determined using data from 3 years of surveillance (2010-2012) on 779 isolates referred by 7 medical centers. The antibiotic test panel included imipenem, ertapenem, meropenem, ampicillin-sulbactam, piperacillin-tazobactam, cefoxitin, clindamycin, moxifloxacin, tigecycline, linezolid, chloramphenicol and . MICs were determined using the agar dilution CLSI reference method. Carbapenem resistance remained low (range 1.1%-2.5%) and unchanged from 2008 to 9 through 2010-2012. Resistance also remained low to the beta-lactam/beta-lactamase inhibitor combinations (1.1%-4.4%). While resistance to clindamycin and moxifloxacin remained high; rates were lower for B. fragilis in 2010-12 (24% and 19% respectively) compared to the earlier time frame of 2008-9 (29% and 35% respectively for the earlier time frame). There were notable species and resistance associations which have been demonstrated previously. No resistance to metronidazole or chloramphenicol resistance was seen. These data demonstrate the continued variability in resistance among Bacteroides and Parabacteroides species, but do demonstrate that carbapenems and beta-lactam/beta-lactamase inhibitor combinations remain very active throughout the United States.

Combination Regimens for Treatment of Carbapenem-Resistant Klebsiella pneumoniae Bloodstream Infections.

Previous studies reported decreased mortality in patients with carbapenemase-producing Klebsiella pneumoniae bloodstream infections (BSIs) treated with combination therapy but included carbapenem-susceptible and -intermediate isolates, as per revised CLSI breakpoints. Here, we assessed outcomes in patients with BSIs caused by phenotypically carbapenem-resistant K. pneumoniae (CRKP) according to the number of in vitro active agents received and whether an extended-spectrum beta-lactam (BL) antibiotic, including meropenem, or an extended-spectrum cephalosporin was administered. We retrospectively reviewed CRKP BSIs at two New York City hospitals from 2006 to 2013, where all isolates had meropenem or imipenem MICs of ≥4 µg/ml. Univariate and multivariable models were created to identify factors associated with mortality. Of 141 CRKP BSI episodes, 23% were treated with a single active agent (SAA), 26% were treated with an SAA plus BL, 28% were treated with multiple active agents (MAA), and 23% were treated with MAA plus BL. Ninety percent of isolates had meropenem MICs of ≥16 µg/ml. Thirty-day mortality was 33% overall and did not significantly differ across the four treatment groups in a multivariable model (P = 0.4); mortality was significantly associated with a Pitt bacteremia score of ≥4 (odds ratio [OR], 7.7; 95% confidence interval [CI], 3.2 to 18.1; P = 0.1), and immunosuppression was protective (OR, 0.4; 95% CI, 0.2 to 1.0; P = 0.04). Individual treatment characteristics were also not significantly associated with outcome, including use of SAAs versus MAA (26% versus 38%, P = 0.1) or BL versus no BL (26% versus 39%, P = 0.1). In summary, in patients with CRKP BSIs caused by isolates with high carbapenem MICs, the role of combination therapy remains unclear, highlighting the need for prospective studies to identify optimal treatment regimens.

U.S.-Based National Sentinel Surveillance Study for the Epidemiology of Clostridium difficile-Associated Diarrheal Isolates and Their Susceptibility to Fidaxomicin.

In 2011 a surveillance study for the susceptibility to fidaxomicin and epidemiology of Clostridium difficile isolates in the United States was undertaken in seven geographically dispersed medical centers. This report encompasses baseline surveillance in 2011 and 2012 on 925 isolates. A convenience sample of C. difficile isolates or toxin positive stools from patients were referred to a central laboratory. Antimicrobial susceptibility was determined by agar dilution (CLSI M11-A8). Clinical and Laboratory Standards Institute (CLSI), Food and Drug Administration, or European Union of Clinical Antimicrobial Susceptibility Testing (EUCAST) breakpoints were applied where applicable. Toxin gene profiles were characterized by multiplex PCR on each isolate. A random sample of 322 strains, stratified by institution, underwent restriction endonuclease analysis (REA). The fidaxomicin MIC90 was 0.5 µg/ml for all isolates regardless of REA type or toxin gene profile, and all isolates were inhibited at ≤1.0 µg/ml. By REA typing, BI strains represented 25.5% of the isolates. The toxin gene profile of tcdA, tcdB, and cdtA/B positive with a tcdC 18-bp deletion correlated with BI REA group. Moxifloxacin and clindamycin resistance was increased among either BI or binary toxin-positive isolates. Metronidazole and vancomycin showed reduced susceptibility (EUCAST criteria) in these isolates. Geographic variations in susceptibility, REA group and binary toxin gene presence were observed. Fidaxomicin activity against C. difficile isolated in a national surveillance study did not change more than 1 year after licensure. This analysis provides baseline results for future comparisons.

Human rhinovirus infections of the lower respiratory tract in hematopoietic stem cell transplant recipients.

BACKGROUND: Human rhinoviruses (HRVs) are a common cause of upper respiratory infection (URI) in hematopoietic stem cell transplant (HSCT) recipients; yet, their role in lower respiratory illness is not well understood. METHODS: We performed a retrospective chart review of HSCT recipients with HRV infection from the time molecular detection methods were implemented at our institution in 2008. Factors associated with proven or possible HRV pneumonia at the first HRV detection were evaluated by univariate and multivariate analysis. We then characterized all episodes of proven and possible HRV pneumonia from the initial HRV infection through a 1-year follow-up period. RESULTS: Between 2008 and 2011, 63 HSCT recipients had ≥1 documented HRV infections. At first HRV detection, 36 (57%) patients had HRV URI and 27 (43%) had proven or possible HRV pneumonia; in multivariate analysis, hypoalbuminemia (odds ratio [OR] 9.5, 95% confidence interval [CI] 1.3-71.7; P = 0.03) and isolation of respiratory co-pathogen(s) (OR 24.2, 95% CI 2.0-288.4; P = 0.01) were independently associated with pneumonia. During the study period, 22 patients had 25 episodes of proven HRV pneumonia. Fever (60%), cough (92%), sputum production (61%), and dyspnea (60%) were common symptoms. Fifteen (60%) episodes demonstrated bacterial (n = 7), fungal (n = 5), or viral (n = 3) co-infection. Among the remaining 10 (40%) cases of HRV monoinfection, patients' oxygen saturations ranged from 80% to 97% on ambient air, and computed tomography scans showed peribronchiolar, patchy, ground glass infiltrates. CONCLUSIONS: HRV pneumonia is relatively common after HSCT and frequently accompanied by bacterial co-infection. As use of molecular assays for respiratory viral diagnosis becomes widespread, HRV will be increasingly recognized as a significant cause of pneumonia in immunocompromised hosts.

Comparison of performance of the novel chromogenic spectra VRE agar to that of bile esculin azide and Campylobacter agars for detection of vancomycin-resistant enterococci in fecal samples.

A total of 142 stool specimens were evaluated for vancomycin-resistant enterococcus (VRE). Twenty-four-hour sensitivities and specificities, respectively, were 98% and 95% for Spectra VRE chromogenic agar (Remel, Lenexa, KS), 86% and 92% for bile esculin azide with vancomycin (BEAV; Remel), and 96.5% and 92% for Campylobacter agar (CAMPY; Remel). Spectra VRE and CAMPY are significantly more sensitive at 24 h than BEAV.

Plasmid comparison and molecular analysis of Klebsiella pneumoniae harbouring bla(KPC) from New York City and Toronto.

OBJECTIVES: This study examined Klebsiella pneumoniae clinical isolates and their bla(KPC) plasmids to determine potential relatedness of the isolates and their plasmids harbouring carbapenem resistance mechanisms. METHODS: K. pneumoniae carbapenemase (KPC)-producing K. pneumoniae from New York City (NYC) (n = 19) and Toronto (n = 2) were typed by PFGE and multilocus sequence typing (MLST). bla(KPC)-harbouring plasmids were transformed into Escherichia coli DH10B(TM), restricted using EcoRI and analysed for bla content and replicon (rep) type. Susceptibility profiles for clinical and transformed strains were determined by automated microbroth dilution using CLSI breakpoints. Outer membrane protein (OMP) genes were analysed by sequencing of ompk35 and ompk36. RESULTS: PFGE analysis identified 17 related strains (≥ 80% similarity; 11 KPC-2, 6 KPC-3) where ST258 was the dominant clonal type. All clinical isolates contained both bla(SHV) and bla(TEM-1) and, with the exception of one isolate, were multidrug resistant (MDR). Transformed KPC plasmids (n = 21) carried TEM-1 (n = 18) and were MDR (n = 5). Three plasmid clusters, repFIIA (n = 10), repR (n = 3) and an unknown type (n = 3), were observed. repFllA plasmids were observed from both NYC and Toronto strains. OMP gene analysis revealed premature stop codons in ompk35 and numerous deletions and insertions in ompk36. CONCLUSIONS: The dissemination of bla(KPC) is due both to carriage of similar KPC-harbouring plasmids within genetically distinct K. pneumoniae and to clonal spread of K. pneumoniae with unrelated KPC plasmids.

Amp C beta-lactamase-producing Escherichia coli in neonatal meningitis: diagnostic and therapeutic challenge.

Antibiotic resistance is a global health priority. Major defenses for Gram-negative bacteria are beta-lactamase enzymes, which have co-evolved with the development and increasing utilization of new antibiotics. Bacteria harboring the plasmid-mediated AmpC enzymes are increasingly prevalent among adult patients, but have not previously been reported in neonates. Early-onset neonatal meningitis caused by an AmpC beta-lactamase-producing Escherichia coli is described for the first time; the plasmid was identified as a transferable CMY-2 family beta-lactamase. Limited experience with newer antibiotics and pharmacokinetics in neonates presents a therapeutic challenge. Currently, there are no Clinical Laboratory Standards Institute (CLSI) recommendations for detecting AmpC nor is the optimal treatment for AmpC-producing organisms known. Thus, it is imperative that clinicians have a high index of suspicion when antimicrobial susceptibility patterns are inconsistent. Development of better microbiology screening tests to rapidly detect resistance is essential. Additionally, pharmacokinetic studies with newer antibiotics in neonates are warranted.

Multilaboratory comparison of growth characteristics for anaerobes, using 5 different agar media.

A multilaboratory study compared the growth of 30 fastidious anaerobes, using 5 different agar media: Wilkins-Chalgren (WC), WC with either whole or laked sheep blood, and Brucella supplemented with vitamin K(1) and hemin and either laked or whole sheep blood. The media were compared for quality and quantity of growth. Experiments were conducted either entirely in an anaerobic chamber or inoculated in ambient air with anaerobic incubation. The results showed that (1) any medium plus whole or laked blood was better than unsupplemented WC, (2) whole blood and laked blood additives gave similar results, (3) supplemented Brucella with whole or laked blood was superior to WC and WC with whole or laked blood, and (4) anaerobic and aerobic inoculation with anaerobic incubation gave similar results. Brucella agar supplemented with whole or laked blood supports the growth of fastidious anaerobic species better than the WC agars do.

Multilaboratory comparison of anaerobe susceptibility results using 3 different agar media.

A 5-laboratory study was performed that used the National Committee for Clinical Laboratory Standards (NCCLS) reference agar dilution method with 3 media formulations to determine whether the use of different media would affect minimum inhibitory concentration (MIC) results. Wilkins-Chalgren, Brucella-based blood agar (BRU), and Wilkins-Chalgren agar plus blood (WCB) and 6 antibiotics (clindamycin, cefoxitin, ceftizoxime, piperacillin, metronidazole, and trovafloxacin) were evaluated with 58 isolates. The MIC values were compared, and a significant correlation of >0.80 was demonstrated for all media and each antibiotic/organism group. The cumulative rate of errors for all antibiotics was 0.1%. These data indicate that a change in the NCCLS reference medium for testing of anaerobic bacteria susceptibility to either BRU or WCB will not affect the MIC results for the antibiotics and organisms evaluated.

National survey on the susceptibility of Bacteroides Fragilis Group: report and analysis of trends for 1997-2000.

The results of a multicenter US survey using the National Committee for Clinical Laboratory Standards currently recommended methodology for measuring in vitro susceptibility of 2673 isolates of Bacteroides fragilis group species were compared from 1997 to 2000. The test panel consisted of 14 antibiotics: 3 carbapenems, 3 beta-lactam-beta-lactamase inhibitors, 3 cephamycins, 2 fluoroquinolones, clindamycin, chloramphenicol, and metronidazole. Declines in the geometric mean minimum inhibitory concentrations were seen with imipenem, meropenem, ampicillin-sulbactam, and the cephamycins. Increased geometric means were observed with the fluoroquinolones and were usually accompanied by an increase in resistance rates. Bacteroides distasonis shows the highest resistance rates among beta-lactam antibiotics, whereas Bacteroides vulgatus shows the highest resistance levels among fluoroquinolones. B. fragilis shows the lowest resistance rates for all antibiotics. All strains were susceptible to chloramphenicol and metronidazole concentrations <8 microgram/mL. The data underscore the need for species identification and continued surveillance to monitor resistance patterns.

Comparative susceptibility patterns of common clinical isolates to cefoperazone: 1981 to 1987.

It has been postulated that the widespread use of broad-spectrum cephalosporins might lead to increased bacterial resistance to such agents. To determine if such increased resistance to cefoperazone might be detectable, the susceptibility patterns of common clinical isolates to cefoperazone were examined from the Pathology Laboratories at Baptist Medical Center, Jacksonville, Florida, from 1981, prior to approval by the Food and Drug Administration, to the present. Gram-negative aerobic and facultative anaerobic organisms, staphylococci, and members of the Bacteroides fragilis group were included in the analysis. The data obtained were compared with results of similar published studies nationwide. No significant decrease in susceptibility to cefoperazone was detected for any gram-negative species examined. A steady increase in the percentage of staphylococci (both coagulase positive and especially coagulase negative) resistant to cefoperazone was demonstrable at this institution. This was a direct function of the concomitant rise in the percentages of staphylococci resistant to methicillin observed over the testing interval. Anaerobic susceptibility patterns of the members of the B. fragilis group were also relatively constant during this period of time. The concentrations of antibiotic inhibiting 50 percent (MIC50) and 90 percent (MIC90) of B. fragilis isolates as determined by an agar dilution technique were 16 micrograms/ml and 64 micrograms/ml, respectively, both in 1981 and in 1987. No change in the national susceptibility patterns of common bacterial isolates to cefoperazone was demonstrable in the five-year period during which the antibiotic has been available for clinical use.

Activity of cefotaxime/desacetylcefotaxime with two aminoglycosides against gram-negative pathogens: an example of interactive synergy.

The susceptibility patterns of clinical Gram-negative isolates were determined to cefotaxime (CTX) and desacetylcefotaxime (dCTX) alone and in combination with gentamicin (GENT) or tobramycin (TOB) by an agar dilution technique. A constant ratio of 1:1 (CTX to dCTX) was tested throughout the study. Isolates were challenged with subinhibitory levels of TOB or GENT in combination with clinically achievable levels of CTX, dCTX and CTX/dCTX to examine the interactions of the agents. Results of this study demonstrate that CTX/dCTX interacts synergistically with aminoglycosides against many Gram-negative pathogens. Synergy (defined as a fourfold or greater decrease in minimum inhibitory concentration (MIC) when CTX/dCTX was compared to CTX/dCTX/TOB) was demonstrable for 55% of isolates tested. Similarly, 45% were synergistically inhibited by CTX/dCTX/GENT. Additivism (a 2-fold decrease in MIC with the same comparisons) was evident for an additional 18 isolates for CTX/dCTX/TOB and 19 with CTX/dCTX/GENT. When data for Pseudomonas spp. were excluded from the analysis, synergy or additivism was evident with CTX/dCTX/TOB for 88% of the organisms tested and 72% with CTX/dCTX/GENT. Synergistic synergy for CTX/dCTX/TOB (an 8- to greater than 16-fold decrease in MIC for CTX) was demonstrable for 35 and 32 of 82 nonspeudomonal isolates respectively with the TOB and GENT combinations. Ninety nine percent of the nonspeudomonal isolates were inhibited by less than 4 micrograms/ml of CTX, 4 micrograms/ml of dCTX and 0.12 micrograms/ml of TOB, or 0.25 micrograms/ml of GENT, respectively.

Evaluation of new technology in the clinical microbiology laboratory.

Technology capable of significantly influencing the practice of clinical microbiology is evolving at an ever-accelerating rate. During their early developmental years, it is difficult to predict which evolving technologies will prove amenable for use in hospital laboratory settings. With the considerable and increasing cost constraints placed on our medical institutions and the resulting budgetary pressures exerted on clinical laboratories, evaluation of developing technology is essential. The Clinical Laboratory Improvement Act of 1988 mandates correlation studies by clinical laboratories as part of the evaluation of all new assays to compare their sensitivities and specificities with those obtained using established methodologies. With shrinking numbers of technologists available for such evaluations, however, the mechanism with which this will be accomplished promises to pose a significant challenge. Factors that demand consideration in any such evaluation include (but are not restricted to) utility, accuracy, prospective time savings, cost of related instrumentation and reagents, and potential for diverse applications. Specific current examples that exemplify the need for such evaluations include the emergence of gene-based techniques such as the polymerase chain reaction as clinical tools, availability of new blood culture systems based on divergent sensor systems, and varying techniques for the the detection of antibodies and antigens for the serodiagnosis of infectious diseases. We as clinical microbiologists have the opportunity to approach the challenges confronting us regarding evaluation of developing technologies with responsible innovation and insight. Only by embracing these responsibilities can we hope to influence the impact of health care reform in the hospital laboratory setting.

In vitro activity of selected cephalosporins and erythromycin against staphylococci and pneumococci isolated at 38 North American medical centers participating in the SENTRY Antimicrobial Surveillance Program, 1997-1998.

The SENTRY Antimicrobial Surveillance Program employs a worldwide network of hospitals to monitor the predominant bacterial and fungal pathogens and antimicrobial susceptibility patterns associated with nosocomial and community-acquired bloodstream, respiratory tract, wound, and urinary tract infections. The purpose of this analysis of SENTRY data is to extract information on the current North American susceptibility patterns of pneumococci and oxacillin-susceptible staphylococci from the comprehensive SENTRY program database. Clinical isolates were provided by 30 centers in the United States (grouped into five regions) and eight centers in Canada. Susceptibility testing was performed at a central reference laboratory using broth microdilution methods and interpretive criteria specified by the National Committee for Clinical Laboratory Standards. Of 34 530 North American bacterial isolates tested during 1997 and 1998, 565 (1.6%) were oxacillin-susceptible, coagulase-negative staphylococci (CoNS). Cefazolin, cefepime, and ceftriaxone all had excellent activity against these CoNS (97.3%-99. 3% susceptible), and 90.4% were susceptible to ceftazidime. A total of 4404 isolates (12.8%) were oxacillin-susceptible Staphylococcus aureus. Overall, 98.9% to 99.2% were susceptible to cefazolin, cefepime, and ceftriaxone; ceftazidime did not have acceptable activity against these S. aureus. Streptococcus pneumoniae accounted for 1665 (4.8%) of North American SENTRY isolates. A total of 1212 isolates (72.8%) were fully susceptible to penicillin (MIC /= 2 microg/ml). The rate of penicillin susceptibility was highest in Canada, and lowest in the South Central and South East regions of the United States. Cefepime, cefuroxime, ceftazidime, and erythromycin all demonstrated excellent efficacy (94%-99.8% susceptibility) against fully penicillin-susceptible isolates of S. pneumoniae. Among pneumococci with intermediate penicillin resistance, 88% were susceptible to cefepime, 92% to cefotaxime, and only 14% to ceftazidime. None of the antimicrobial agents in this analysis demonstrated adequate activity against fully penicillin-resistant pneumococci. In summary, the fourth-generation cephalosporin, cefepime, demonstrated consistently excellent efficacy against oxacillin-susceptible staphylococci and most pneumococci, and remains an appropriate choice for empiric therapy of serious infections.

Practical approach to the identification of clinically relevant Enterococcus species.

Enterococci have become important nosocomial pathogens, with Enterococcus faecalis and then Enterococcus faecium predominating. Because of the emergence of glycopeptide (vancomycin and teicoplanin) resistance in enterococci, laboratories have been required to screen for resistant strains and to identify them to the species level. This has resulted in the need for accurate identification of species less commonly associated with clinical infections, such as Enterococcus casseliflavus and Enterococcus gallinarum, which are inherently resistant to the glycopeptides. Studies evaluating commonly used commercial identification systems, have found error rates for enterococcal species identification of 2-21% for E. faecalis, 5-9% for E. faecium, and 14-79% for other species. Reporting errors may have adverse effects on the management of clinical infections, as well as in the control of multidrug-resistant strain outbreaks. The purpose of this document is to present a simplified approach to the identification of Enterococcus species that uses a combination of rapid, readily available, and inexpensive tests.

Global distribution of Streptococcus pneumoniae serotypes isolated from paediatric patients during 1999-2000 and the in vitro efficacy of telithromycin and comparators.

Few data exist on the distribution of Streptococcus pneumoniae serotypes in many countries and in non-invasive disease overall. Here, data are presented from 772 paediatric isolates from children with community-acquired respiratory tract infections isolated from the PROTEKT global surveillance study during 1999-2000. Overall, 60.0 % of isolates were covered by the 7-valent pneumococcal vaccine formulation (PCV7), with greater coverage in the USA compared with Europe (69.6 vs 55.5 %, P = 0.014). Geographically dispersed clones of serogroups 3, 11 and 15 accounted for most of the isolates outside PCV7 coverage. Overall, macrolide, penicillin and cotrimoxazole non-susceptibility rates were high; however, all isolates were susceptible to telithromycin. Although only 7.4 % of isolates were resistant to amoxycillin/clavulanate, a higher prevalence of resistance was found in isolates from the USA and South Korea. This study shows the feasibility and importance of serotyping antibiotic surveillance study isolates and the potential of telithromycin as an important option for empiric therapy.