CHROMagar Orientation medium reduces urine culture workload.

Microbiology laboratories continually strive to streamline and improve their urine culture algorithms because of the high volumes of urine specimens they receive and the modest numbers of those specimens that are ultimately considered clinically significant. In the current study, we quantitatively measured the impact of the introduction of CHROMagar Orientation (CO) medium into routine use in two hospital laboratories and compared it to conventional culture on blood and MacConkey agars. Based on data extracted from our Laboratory Information System from 2006 to 2011, the use of CO medium resulted in a 28% reduction in workload for additional procedures such as Gram stains, subcultures, identification panels, agglutination tests, and biochemical tests. The average number of workload units (one workload unit equals 1 min of hands-on labor) per urine specimen was significantly reduced (P < 0.0001; 95% confidence interval [CI], 0.5326 to 1.047) from 2.67 in 2006 (preimplementation of CO medium) to 1.88 in 2011 (postimplementation of CO medium). We conclude that the use of CO medium streamlined the urine culture process and increased bench throughput by reducing both workload and turnaround time in our laboratories.

Evaluation of MRSASelect (™) chromogenic medium for the early detection of methicillin-resistant Staphylococcus aureus from blood cultures.

INTRODUCTION: Staphylococcus aureus bacteremia is associated with considerable morbidity and mortality. In theory, reducing the turnaround time in reporting of methicillin-resistant S aureus (MRSA) among patients with bactermia could assist with the rapid optimization of antimicrobial therapy. OBJECTIVE: To evaluate the sensitivity and specificity of MRSASelect (Bio-Rad Laboratories, USA), a chromogenic medium, in the early detection of MRSA from blood cultures growing Gram-positive cocci in clusters, and to confirm that routine use of this medium would, in fact, reduce turnaround time for MRSA identification. METHODS: The present study was conducted at three microbiology laboratories in Manitoba. Between April 2010 and May 2011, positive blood cultures with Gram-positive cocci in clusters visualized on Gram stain were subcultured to both MRSASelect and routine media. MRSA isolates were identified using conventional microbiological methods from routine media and using growth with the typical colony morphology (pink colony) on MRSASelect medium. RESULTS: A total of 490 blood cultures demonstrating Gram-positive cocci in clusters on Gram stain were evaluated. S aureus was recovered from 274 blood cultures, with 51 S aureus isolates (51 of 274 [18.6%]) identified as MRSA. MRSASelect medium had a sensitivity of 98%, a specificity of 100%, a positive predictive value of 100% and a negative predictive value of 99.8% for the recovery and identification of MRSA directly from positive blood culture bottles. In addition, use of MRSASelect medium was found to improve turnaround time in the detection of MRSA by almost 24 h relative to conventional methods. DISCUSSION: These data support the utility of MRSASelect medium for the rapid identification of MRSA from positive blood cultures. Further clinical studies are warranted to determine whether the improvement in turnaround time will result in a measurable reduction in suboptimal antimicrobial therapy and/or improvement in patient outcome.

HISTORIQUE: La bactériémie à Staphylococcus aureus s'associe à une morbidité et une mortalité considérables. En théorie, la réduction du délai à confirmer un S aureus résistant à la méthicilline (SARM) chez les patients ayant une bactériémie pourrait contribuer à l'optimisation rapide de la thérapie antimicrobienne. OBJECTIF: Évaluer la sensibilité et la spécificité du MRSASelect (Bio-Rad Laboratories, États-Unis), un milieu de culture chromogène, pour déceler rapidement le SARM dans des cultures sanguines contenant des coccobacilles à Gram positif en grappes et confirmer que l'utilisation systématique de ce milieu de culture réduit véritablement le délai de dépistage du SARM. MÉTHODOLOGIE: Les chercheurs ont mené la présente étude dans trois laboratoires de microbiologie du Manitoba. Entre avril 2010 et mai 2011, les cultures sanguines positives aux coccobacilles à Gram positif en grappes visualisées sur une coloration de Gram ont été repiquées à la fois dans un milieu de culture MRSASelect et dans un milieu de culture habituel. Les chercheurs ont repéré des isolats de SARM au moyen des méthodes microbiologiques classiques dans les milieux de culture habituels et des milieux de culture ayant la morphologie classique des colonies (colonie rose) sur les milieux de culture MRSASelect. RÉSULTATS: Au total, les chercheurs ont évalué 490 cultures sanguines démontrant des cocccobacilles à Gram positif en grappes sur une coloration de Gram. Ils ont prélevé le S aureus sur 274 analyses sanguines et déterminé que 51 isolats de S aureus (51 sur 274 [18,6 %]) étaient un SARM. Le milieu de culture MRSASelect avait une sensibilité de 98 %, une spécificité de 100 %, une valeur prédictive positive de 100 % et une valeur négative prédictive de 99,8 % à l'égard de la récupération et du dépistage du SARM directement dans les fioles de culture sanguine. De plus, l'utilisation du milieu de culture MRSASelect raccourcissait de près de 24 heures le délai de dépistage du SARM par rapport aux méthodes classiques. EXPOSÉ: Ces données appuient l'utilité du milieu de culture MRSASelect pour dépister rapidement le SARM dans les cultures sanguines positives. D'autres études cliniques s'imposent pour déterminer si l'obtention plus rapide des résultats s'associera à une réduction mesurable de la thérapie antimicrobienne sous-optimale ou à une amélioration de l'issue des patients.

Evaluation of BacT/Alert 3D automated unit for detection of nontuberculous mycobacteria requiring incubation at 30 degrees C for optimal growth.

The reliability of the BacT/Alert 3D unit for automated detection of nontuberculous mycobacteria (NTM) that grow optimally at 30 °C was assessed. This system reliably maintained a temperature of 30 °C and detected 50% of the clinical NTM strains (5 Mycobacterium marinum and 3 Mycobacterium gordonae strains) faster than 37 °C culture.

Ureaplasma parvum as a cause of sternal wound infection.

Few reports in the literature have documented the isolation of Ureaplasma species from sternal wounds. A case of sternal wound infection likely due to Ureaplasma parvum is described. When routine bacterial cultures from a sternal wound infection fail to yield a pathogen, diagnostic testing for mycoplasmas and ureaplasmas should be considered.

Reductions in workload and reporting time by use of methicillin-resistant Staphylococcus aureus screening with MRSASelect medium compared to mannitol-salt medium supplemented with oxacillin.

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in both nosocomial and community settings, and screening for carriers is an important infection control practice in many hospitals. In this retrospective study, we demonstrate that the implementation of an MRSA screening protocol using a selective chromogenic medium (MRSASelect) reduced the workload for this screening test by 63.7% overall and by 12.6% per specimen and reduced the turnaround time for reporting by an average of 1.33 days for all MRSA screening specimens, 1.97 days for MRSA-positive specimens, and 1.3 days for MRSA-negative specimens compared to standard mannitol-salt agar supplemented with 6 mg of oxacillin/liter.

Microfiber cloths reduce the transfer of Clostridium difficile spores to environmental surfaces compared with cotton cloths.

BACKGROUND: Environmental surfaces in health care facilities contaminated with Clostridium difficile spores can be a reservoir that contribute to transmission of hospital-acquired infections. Microfiber cleaning cloths may improve the effectiveness of surface cleaning. The objective of this study was to assess the removal and transfer of C difficile spores on surfaces cleaned by microfiber compared with cotton cloths. METHODS: C difficile spores (approximately 4.2 log(10)/site) were applied to ceramic surfaces. Microfiber or cotton cloths were used to wipe the surfaces that were sprayed with either buffer or a nonsporicidal cleaning agent. To ensure reproducible pressure and surface contact time, a drill apparatus was used. The pressure was 1.5-1.77 N, and the total number of rotations was 10. Viable counts were used to assess the efficiency of microfiber and cotton cloths in removing and transferring spores. RESULTS: Of 4.4 log(10)C difficile spores inoculated on a ceramic surface, microfiber and cotton cloths removed 2.4 and 1.7 log(10), respectively. Microfiber cloths containing 4.2 log(10)C difficile spores transferred 1.7 log(10) C difficile spores when used to wipe a ceramic surface compared with cotton cloths that transferred 2.4 log(10). Similarly microfiber wipes transferred fewer spores on consecutive surfaces wiped compared with cotton cloths (0.8 log(10) vs 1.80 log(10)). CONCLUSION: The use of microfiber cloths may reduce the risk of C difficile spore transfer during surface cleaning.

UF-1000i flow cytometry is an effective screening method for urine specimens.

This study was undertaken to evaluate the UF-1000i™ (UF) flow cytometer to count urine constituents including bacteria. The objective was to screen urine samples and determine what white blood cell (WBC) and/or bacteria screening criteria would minimize the number of specimens cultured yet ensuring that all true positives were cultured. UF screening and culture on CHROMagar™ Orientation (CO) medium were performed on 2496 specimens. Various combinations of WBC/bacterial counts were assessed as screening criteria and correlated with significant growth on CO medium. A bacterial count of ≥20 from UF gave an overall screening sensitivity of 92.6%, allowing 35% of specimens to be screened out and not cultured. The sensitivity was 99.2% and 85.0% for Gram-negative and Gram-positive organisms, respectively, using the same bacterial count. Our study indicated that UF was a simple, rapid, and reliable method for urine screening when the bacterial count of ≥20 was used as the sole screening criterion.

First report of Actinobaculum schaalii urinary tract infection in North America.

A recurrent urinary tract infection with Actinobaculum schaalii, a fastidious, facultative anaerobic, and emerging pathogen, is described. Diagnosis was delayed when routine urine cultures were initially performed yielding recurrently negative results. Resolution of symptoms occurred after anaerobic cultures were done to allow organism isolation, identification, and appropriate antimicrobial treatment.