Dio-Sensimedia: a novel culture medium for rapid detection of extended spectrum beta-lactamases

Superintendence of antimicrobial resistance observed in bacterial flora isolated from human faecal carriage in Vellore, India

A frequent cross-sectional study was conducted to determine the patterns of antimicrobial resistance in 296 bacterial strains isolated from in-patient faecal samples of Government Vellore Medical College and Hospital, Vellore. Isolation and identification of bacterial strains were done using enrichment media, selective media, and biochemical tests. Antimicrobial susceptibility testing by the disc diffusion method and minimal inhibitory concentration method was conducted and the strains were subjected to extended spectrum beta-lactamases screening. Antibiotic sensitivity pattern of Staphylococcus spp. showed oxacillin resistance. Almost all the strains were sensitive to linezolid, vancomycin, gentamycin and chloramphenicol. In gram negative isolates ciprofloxacin and tobramycin showed better sensitivity and ceftazidime showed a higher percentage of resistance by MIC. Out of 250 isolates, Enterobacteriaceae showed positive for 86/250, 82/250 and 94/250 isolates and 3/10, 4/10 and 4/10 non-Enterobacteriaceae isolates were found to be positive for CTX-M gene, TEM gene and SHV gene, respectively. This study helps to assess/analyse the relation between the spectrum of microorganisms present in various grades of faecal carriage and their susceptibility pattern in this part of the Vellore town.

Risk factors of organ failure in cholangitis with bacteriobilia

AIM: To identify the risk factors for organ failure (OF) in cholangitis with bacteriobilia.

METHODS: This study included 182 patients with acute cholangitis who underwent percutaneous transhepatic biliary drainage between January 2005 and April 2013. We conducted a retrospective analysis of comprehensive clinical and laboratory data.

RESULTS: There were 24 cases (13.2%) of OF and five deaths (2.7%). Bile culture was positive for microbial growth in 130 out of 138 (94.2%) patients. In multivariate analysis of 130 patients with positive bile cultures, significant predictive factors for OF were the presence of extended-spectrum beta-lactamase (ESBL) organisms in blood cultures, pre-existing renal dysfunction, and choledocholithiasis as an etiology, with odds ratios of 15.376, 6.319, and 3.573, respectively. We developed a scoring system with a regression coefficient of each significant variable. The OF score was calculated using the following equation: (2.7 × ESBL organisms in blood cultures) + (1.8 × pre-existing renal dysfunction) + (1.3 × choledocholithiasis). This scoring system for predicting OF was highly specific (99.1%) and had a positive predictive value of 86.2%.

CONCLUSION: ESBL organisms in blood cultures, pre-existing renal dysfunction, and choledocholithiasis are risk factors for OF in cholangitis with bacteriobilia. The OF scoring system may aid clinicians to identify a poor prognosis group.

Risk factors of organ failure in patients with bacteremic cholangitis

BACKGROUND

Bacteremic cholangitis carries a high mortality rate of up to 10 % in relation to organ failure (OF), including septic shock.

AIM

The purpose of this study was to elucidate predictive factors for OF in bacteremic cholangitis.

METHODS

A retrospective review of all patients diagnosed with acute cholangitis and proven bacteremia from 2003 to 2011 was performed. Comprehensive clinical and laboratory data of 211 patients were analyzed.

RESULTS

There were 42 cases (19.9 %) of OF and 5 deaths (2.4 %). In the multivariate logistic regression analysis, significant predictive factors for OF were successful biliary decompression, presence of extended-spectrum beta-lactamase organism (ESBL), higher total bilirubin, and higher blood urea nitrogen (BUN) level at admission with odds ratios (ORs) of 0.129, 6.793, 1.148, and 1.089, respectively. Subgroup analysis of 165 patients who underwent biliary decompression before an event (with OF: 20, without OF: 145) was performed to elucidate the risk factors for organ failure even after successful biliary drainage. Variables significantly associated with OF included ESBL and BUN (OR = 4.123 and 1.177, respectively). We developed a scoring system with regression coefficient of each significant variable. The organ failure score was calculated using the following equation: (1.4 × ESBL) + (0.2 × BUN). This scoring system for predicting OF was highly sensitive (85.0 %) and specific (83.4 %).

CONCLUSIONS

Biliary decompression, ESBL, total bilirubin, and BUN are prognostic determinants in patients with bacteremic cholangitis. An organ failure scoring system may allow clinicians to identify groups with poor prognosis even after successful biliary decompression.

Rapid 4 to 6 hour detection of extended-spectrum beta-lactamases in a routine laboratory

With the growing frequency of extended-spectrum beta-lactamases (ESBL) among Enterobacteriaceae, treatment of Gram-negative nosocomial infections requires rapid and reliable detection of this enzyme. Quicolor agar (QC agar) (Salubris Inc., Massachusetts, USA) is a novel chromogenic agar medium changing colour within 4 to 6 h due to the metabolic activity of growing bacteria. This study investigated the use of QC agar compared to Mueller Hinton agar (MH) for the detection of ESBL using disk diffusion and E-test. 100 Enterobacteriaceae isolated at Hacettepe University Hospital, of which 50 were predetermined to be ESBL positive and 50 as negative using the CLSI disk diffusion ESBL (phenotypic confirmatory test) criteria. For disk diffusion and E-test, cefotaxime+/-clavulanate (CT/CTL) and ceftazidime+/-clavulanate (TZ/TZL) were used, and for E-test, cefepime+/-clavulanate (PM/PML) was also used. QC agar rapid ESBL results for all strains were in agreement with the standard overnight procedure. All 50 ESBL positives were detected by both methods. For the 50 ESBL negatives, QC agar rapid results from E-test and disk diffusion were in complete accordance with the overnight MH results. Moreover, E-test detected 8 additional ESBL positive strains that disk diffusion missed. For disk diffusion, CT/CTL alone detected all 50 ESBL positives while TZ/TZL alone missed 5 ESBL positives. E-test CT/CTL alone confirmed all 50 ESBL positives and identified 4 additional ESBL-positive strains. When used together, E-test CT/CTL, TZ/TZL and PM/PML identified a total of 58 ESBL positives among the 100 strains tested. QC agar can be used for rapid and reliable ESBL detection within 4 to 6 h, using disk diffusion and E-test ESBL reagents. This rapid method should be further validated using genotype characterized ESBL and other beta-lactamase positive strains.