Evaluation of a new selective medium, BD BBL CHROMagar MRSA II, for detection of methicillin-resistant Staphylococcus aureus in different specimens.

The sensitivity of screening for methicillin-resistant Staphylococcus aureus (MRSA) can be improved by adding other specimen sites to nares. We describe an evaluation of a new selective medium, BBL CHROMagar MRSA II (CMRSAII), for its ability to detect MRSA from different specimen types. CMRSAII is a chromogenic medium which incorporates cefoxitin for the detection of MRSA. A study was performed at four clinical laboratories with the following specimens: 1,446 respiratory, 694 stool, 1,275 skin, and 948 wound specimens and 688 blood culture bottles containing Gram-positive cocci. The recovery of MRSA on traditional culture media was compared to results with CMRSAII. S. aureus was tested by cefoxitin disk diffusion. CMRSAII was interpreted as positive for MRSA at 24 h (range, 18 to 28 h) based solely on the visualization of mauve-colored colonies and at 48 h (range, 36 to 52 h) based on detection of mauve colonies with subsequent confirmation as S. aureus (by coagulase or latex agglutination testing). MRSA was recovered more frequently on CMRSAII (89.8% at 24 h and 95.6% at 48 h) than on traditional culture plates (83.1% at 24 h and 79.8% at 48 h) for all specimen types combined (P < 0.001). The percent sensitivities of CMRSAII at 24- and 48-h reads, respectively, were 85.5 and 92.4% for respiratory specimens, 87.9% and 98.3% for stool specimens, 88.4% and 96.1% for skin specimens, 92.1% and 94.6% for wound specimens, and 100% and 100% for positive blood cultures. The specificity was 99.8% for respiratory specimens and 100% for all others. In conclusion, CMRSAII is a reliable screening medium for multiple specimen types.

High interlaboratory reproducibility of matrix-assisted laser desorption ionization-time of flight mass spectrometry-based species identification of nonfermenting bacteria.

Matrix-assisted laser desorption ionization-time of flight mass spectrometry has emerged as a rapid, cost-effective alternative for bacterial species identification. Identifying 60 blind-coded nonfermenting bacteria samples, this international study (using eight laboratories) achieved 98.75% interlaboratory reproducibility. Only 6 of the 480 samples were misidentified due to interchanges (4 samples) or contamination (1 sample) or not identified because of insufficient signal intensity (1 sample).

[Prevention and control of the spread of vancomycin-resistant enterococci: results of a workshop held by the German Society for Hygiene and Microbiology]. / Prävention und Kontrolle der Ausbreitung von Vancomycin-resistenten Enterokokken: Ergebnisse eines Workshops der Deutschen Gesellschaft für Hygiene und Mikrobiologie.

The incidence of vancomycin-resistant enterococci (VRE), especially E. faecium, is increasing in several German hospitals and some facilities have experienced VRE outbreaks. The German National Nosocomial Infection Surveillance System has also noticed a sharp increase in the incidence of nosocomial VRE infections per 10,000 patients from 0.5 in 2003 to 11.0 in 2005 accompanied by a rise in VRE-associated mortality. However, the reasons of this increase remain unknown. As VRE may cause severe nosocomial infections, transmission must be restricted. This article provides the guidelines as defined by the workshop of the German Society for Hygiene and Microbiology for the prevention of VRE transmission in both, endemic and epidemic, settings. The following topics are discussed: indication for VRE screening, microbiological diagnostics, general infection control measures (isolation precautions and use of protective clothing) and additional hygiene measures in the nosocomial VRE outbreak setting.

Spread of ampicillin/vancomycin-resistant Enterococcus faecium of the epidemic-virulent clonal complex-17 carrying the genes esp and hyl in German hospitals.

The incidence of vancomycin-resistant Enterococcus faecium isolation was low (

Evaluation of a rapid direct assay for identification of bacteria and the mec A and van genes from positive-testing blood cultures.

We performed the first evaluation of a DNA strip assay (GenoType blood culture; Hain Lifescience, Nehren, Germany) for the detection of the most relevant bacterial sepsis pathogens directly from positive BACTEC blood culture bottles (Becton Dickinson, Heidelberg, Germany). The test comprises two panels, one for the direct species identification of important gram-positive cocci and the other for gram-negative rods. Additionally, detection of the mec A and the van genes are implemented. The GenoType assay was validated regarding its analytical sensitivity with blood cultures spiked with reference strains. Approximately 10(4) CFU per ml were detected. Analytical specificity was calculated with a test panel of 212 reference strains. Of the strains tested, 99% were correctly identified. Additionally, 279 consecutive blood cultures signaled positive by BACTEC were processed directly, in comparison to conventional methods. The GenoType assays were performed according to Gram stain morphology. A total of 243 (87.1%) of the 279 organisms isolated were covered by specific probes. A total of 152 organisms were gram-positive cocci, of which 148 (97.4%) were correctly identified by the GenoType assay. Ninety-one organisms were gram-negative rods, of which 89 (97.8%) were correctly identified. Concerning mec A gene detection, GenoType assay correctly detected 12 of 13 methicillin-resistant Staphylococcus aureus isolates. One Enterococcus faecium isolate with a positive van A gene isolated was correctly differentiated by the assay. All results were available 4 h after the results of microscopic analysis. The evaluated GenoType blood culture assay showed fast and reliable results in detecting the most important sepsis pathogens and the mec A and van genes directly from positive blood culture bottles.

Analysis of the comparative workflow and performance characteristics of the VITEK 2 and Phoenix systems.

The VITEK 2 (bioMérieux, Marcy L'Etoile, France) and the Phoenix systems (BD Diagnostic Systems, Sparks, Md.) are automated instruments for rapid organism identification and susceptibility testing. We evaluated the workflow, the time to result, and the performance of identification and susceptibility testing of both instruments. A total of 307 fresh clinical isolates were tested: 141 Enterobacteriaceae, 22 nonfermenters, 93 Staphylococcus spp., and 51 Enterococcus spp. Manipulation time was measured in batches, each with seven isolates, for a total of 39 batches. The mean (+/- standard deviation [SD]) manipulation time per batch was 20.9 +/- 1.8 min for Phoenix and 10.6 +/- 1.0 min for VITEK 2 (P < 0.001). Mean (+/-SD) time to result for all bacterial groups was 727 +/- 162 min for Phoenix and 506 +/- 120 min for VITEK 2 (P < 0.001). Concerning identification, Phoenix and VITEK 2 yielded the same results for nonfermenters (100%), staphylococci (97%), and enterococci (100%). For 140 Enterobacteriaceae strains evaluated, 135 (96%) were correctly identified by Phoenix and 137 (98%) by VITEK 2 (P = 0.72). The overall category agreement for all isolates was 97.0% for both instruments. The minor error rate, major error rate, and very major error rate for all bacterial isolates tested were 3.0, 0.3, and 0.6 and 2.8, 0.2, and 1.7 for Phoenix and VITEK 2, respectively (P values of 0.76, 0.75, and 0.09). The VITEK 2 system required less manual manipulation time and less time than the Phoenix system to yield results.

Treatment of life-threatening multiresistant staphylococcal and enterococcal infections in patients with end-stage renal failure with quinupristin/dalfopristin: preliminary report.

BACKGROUND: Life-threatening infections with multiresistant gram-positive bacteria are increasing. Treatment with quinupristin/dalfopristin (Q-D) has turned out to be effective against such resistant pathogens. PATIENTS AND METHODS: We report on treatment of six patients on dialysis (four with additional liver injury) and of one renal graft recipient with normal renal function who had severe infections caused by multiresistant Staphylococus epidermidis (1/7), methicillin-resistant Staphylococcus aureus (4/7) and vancomycin-resistant Enterococcus faecium (2/7). RESULTS: Six out of seven patients were cured by therapy with Q-D in adjusted doses lasting for 10 to 34 days. Pharmacokinetics of Q-D and its metabolites were determined and remained within the therapeutic range, despite a modest increase of all compounds at the presumed steady state. The concentrations of the metabolites of Q-D were clearly lower than the parent drugs, including those of quinupristin-conjugated derivatives, which has not been reported previously. CONCLUSION: These preliminary results suggest that: a) neither quinupristin nor dalfopristin or its metabolites accumulated despite the long duration of treatment; b) no adjustment of the standard dosage regimen (three times 7.5 mg/kg/day) is necessary in end-stage renal disease.

Evaluation of a new chromogenic medium for the isolation and presumptive identification of Salmonella species from stool specimens.

The performance of BBL CHROMagar Salmonella (Becton Dickinson, France), a new selective chromogenic medium for the isolation and presumptive identification of Salmonella spp., was evaluated. On this medium, which is a modification of CHROMagar Salmonella (CHROMagar Microbiology, France) with enhanced selectivity, the colonies of Salmonella are stained in mauve (rose-violet), while those of other organisms appear in blue-green or are not stained by any of the chromogens of the medium. The medium was evaluated with a total of 176 strains of Salmonella and other organisms, consisting of 18 reference strains and 158 clinical isolates. All Salmonella strains except subspecies IIIa and IIIb strains and Salmonella Gallinarum yielded typical mauve colonies. During the evaluation with 107 known positive and 332 unknown stool specimens in a clinical laboratory, a total of 115 and 105 Salmonella isolates were obtained on BBL CHROMagar Salmonella and Hektoen enteric agar, respectively. From the known positive stool specimens, 92 true positive cultures were obtained on BBL CHROMagar Salmonella and 89 on Hektoen enteric agar, yielding sensitivities of 86 and 83%, respectively. From the unknown stool specimens, a total of 27 Salmonella isolates were obtained, with 23 isolated from BBL CHROMagar Salmonella and 16 from Hektoen enteric agar by direct plating (sensitivity 85 and 59%, specificity 99 and 97%, respectively). Seroagglutination tests could be performed directly from BBL CHROMagar Salmonella. Compared to conventional isolation media, the time needed for confirmatory biochemical and serological tests was shortened by about 1 day when BBL CHROMagar Salmonella was used. On the basis of these results, the medium can be recommended for the primary isolation and presumptive identification of Salmonella spp. from clinical stool specimens.

Evaluation of BBL CHROMagar orientation medium for detection and presumptive identification of urinary tract pathogens.

The microbiological performance of BBL CHROMagar Orientation medium and CPS ID2 agar was compared to that of Columbia agar with 5% sheep blood and MacConkey agar without crystal violet for the enumeration and presumptive identification of bacteria responsible for urinary tract infections. Of a total of 658 clinical urine specimens, 118 specimens yielded no growth, 402 specimens yielded growth with cell counts of > or = 10(5) CFU/ml, and 138 specimens yielded growth with cell counts of < 10(5) CFU/ml. Of the specimens with cell counts of > or = 10(5) CFU/ml, 163 were pure cultures and 239 were mixed cultures. A total of 266 Escherichia coli organisms were isolated on both chromogenic media, 260 were isolated on blood agar, and 248 were isolated on MacConkey agar. One strain (0.4%) failed to develop the expected pink color on CHROMagar Orientation medium, and 23 strains (8.7%) failed to develop the expected pink color on CPS ID2 agar. Enterococci (CHROMagar Orientation medium, n = 266; CPS ID2 agar, n = 265) produced small blue-green colonies on both chromogenic media. Fifty of the mixed cultures contained enterococci that were detected only on the chromogenic media. The Klebsiella-Enterobacter-Serratia (KES) and the Proteus-Morganella-Providencia (PMP) groups could be identified on both chromogenic media. Of 66 isolates of the KES group, 63 grew with the expected color on CHROMagar Orientation medium and 58 of 64 isolates grew with the expected color on CPS ID2 agar. Other microorganisms required further identification. The use of chromogenic medium formulations offers a time-saving method for the reliable detection, enumeration, and presumptive identification of urinary tract pathogens. One of the greatest advantages of these media is the easy recognition of mixed cultures.

[Meningitis caused by Streptococcus suis type 2 in an adult]. / Erwachsenen-Meningitis durch Streptococcus suis Typ 2.

HISTORY AND ADMISSION FINDINGS: A 54-year-old huntsman who 3 days previously had shot a wild pig, developed severe headache, nausea and vomiting over the last 10 hours. Physical examination was unremarkable except for an 8 x 4 cm large reddening of the skin over the right tibia and fever (38.2 degrees C). INVESTIGATIONS: Cranial computed tomography was normal. Cerebrospinal fluid showed pleocytosis (5.200 cells/mm3). Gram-stained (CSF) smear showed gram-positive cocci and an increased white cell count (14,000/microliters) was found in blood. DIAGNOSIS, TREATMENT AND COURSE: After the diagnosis of bacterial meningitis had been made antibiotics were given intravenously (penicillin G 10 mill. IU, three times daily on days 1 to 16: at first with cefotaxim, three times daily 2 g on days 1 to 3, then with gentamicin twice 80 mg on days 3 to 13). The acute neurological signs quickly regressed, the pretibial reddening (presumably at the port of entry) disappeared, as did the fever on the 4th day of the illness. The streptococci isolated from CSF and blood were identified as 5. suis type 2 (Lancefield group R). But despite the early and effective antibiotic treatment cochleovestibular symptoms (hearing impairment, vertigo and unsteady gait) set in after initial improvement, a frequent complication of S. suis meningitis. CONCLUSION: S. suis should be considered as the causative organism of generalized septicaemia and meningitis in adults, if the history reveals contact with domestic or wild pigs and there are early cochleovestibular signs.

[How fastidious are the so-called non-fastidious neisseriae? (AUTHOR'S TRANSL)]. / Wie anspruchslos sind die sog. anspruchslosen Neisserien?

75 strains of all the so-called non-fastidious Neisseria species were examined for their ability to grow on blood and nutrient agar at temperatures between 22 degrees C and 45 degrees C. The result was that only Neisseria mucosa var. mucosa, N. catarrhalis, N. ovis and N. canis grow sufficiently on nutrient agar at 22 degrees C. N. lactamica has an even narrower range of of growth (30-37 degrees C) than meningococci. Therefore, the statement in Bergey's Mnaual that the saprophytic neisseriae can be separated from the pathogenic species by their minor needs for temperature and media should be corrected.