Culture and culture-independent diagnostic tests in Campylobacter enteritis.

INTRODUCTION: Campylobacter infections are among the most common causes of bacterial enteritis. This study aims to determine the sensitivity, specificity and positive predictive values (PPV) of culture and culture-independent tests for the diagnosis of Campylobacter enteritis. METHODOLOGY: A total of 400 stool samples were included in the study. BD MAX enteric bacterial panel (BD Diagnostics, Franklin Lakes, NJ, USA) and EntericBio Gastro Panel II (Serosep, Limerick, Ireland) were used as commercial molecular tests. RIDA®QUICK Campylobacter (R-Biopharm, Darmstadt,, Germany) and CerTest (Biotec, Zaragoza, Spain) were used to detect Campylobacter antigens. Samples were cultured in CCDA media and subjected to bacterial identification by mass spectrometry. RESULTS: Among the 400 specimens, 41 (10.2%) were evaluated as Campylobacter positive; 21 were culture-positive and 20 were detected as positive by both PCR methods. Of the 21 isolates grown in culture, 16 (76.2%) were identified as C. jejuni and 5 (23.8%) as C. coli. While all 21 culture-positive specimens were detected as positive by both molecular tests, 18 of the specimens were found positive by RidaQuick, and 16 by Certest ICA. Of the 20 culture-negative Campylobacter cases, 18 were positive by RidaQuick and 12 by Certest ICA. Sensitivities of culture, ICA-RidaQuick and ICA-CerTest were 51.2%, 87.8 and 68.3, respectively. The specificities of all tests were in the range of 90-100 %. PPV of molecular tests, ICA-RidaQuick and ICA-CerTest were > 95%, 72 % and 48.3 %, respectively. CONCLUSIONS: Molecular tests were superior to culture and ICA in terms of sensitivity, specificity, and positive predictive value.

Investigation of carbapenemase and mcr-1 genes in carbapenem-resistant Klebsiella pneumoniae isolates.

INTRODUCTION: Carbapenem-resistant Klebsiella pneumoniae are a major problem. We aimed to investigate carbapenemase-encoding genes and transferable mcr-1 genes among 57 carbapenem-resistant Klebsiella pneumoniae (CRKP) isolates from hospitalized patients. METHODOLOGY: Antibiotic susceptibility tests were performed by Phoenix (BD). Results for ertapenem and colistin were confirmed by gradient diffusion and microdilution methods. Carbapenemase and mcr-1 genes were investigated by Polymerase Chain Reaction (PCR). RESULTS: Thirty-two (56.14%) isolates were from intensive care units (ICU). Antibiotic resistance rates by Phoenix: 52.63% for amikacin; 73.69% trimethoprim sulfamethoxazole; 91.23% cefepime; 82.46% tigecycline; 59.65% colistin. Carbapenemases positivity: 82.45% (47) for blaOXA-48, 40.35% (23) blaOXA-55, 3.50% (2) blaOXA-51, 1.75% (1) blaOXA-23, 1.75% (1) blaOXA-24, 1.75% (1) blaIMP. blaOXA-58, blaKPC, blaNDM-1, and blaVIM were not detected. Twenty (35.08%) isolates had both blaOXA-48 and blaOXA-55. Three isolates were mcr-1 (+) and blaOXA-48 (+). One mcr-1 (+) isolates was blaOXA-51 (+). One colistin sensitive isolate determined by Phoenix, was found colistin resistant by microdilution. CONCLUSION: OXA-48 and OXA-55 co-harboring isolates and mcr-1 gene (+) isolates were spreading. Automated colistin susceptibility results should be confirmed by microdilution method. Resistance mechanisms in Enterobacteriaceae should be determined and the isolates should be monitored by molecular epidemiological methods. Effective infection control measures will contribute to reduce risk of antibiotic resistant bacterial infections and dissemination of antibiotic resistance.