Impact of the ST101 clone on fatality among patients with colistin-resistant Klebsiella pneumoniae infection.

Objectives: We describe the molecular characteristics of colistin resistance and its impact on patient mortality. Methods: A prospective cohort study was performed in seven different Turkish hospitals. The genotype of each isolate was determined by MLST and repetitive extragenic palindromic PCR (rep-PCR). Alterations in mgrB were detected by sequencing. Upregulation of pmrCAB, phoQ and pmrK was quantified by RT-PCR. mcr-1 and the genes encoding OXA-48, NDM-1 and KPC were amplified by PCR. Results: A total of 115 patients diagnosed with colistin-resistant K. pneumoniae (ColR-Kp) infection were included. Patients were predominantly males (55%) with a median age of 63 (IQR 46-74) and the 30 day mortality rate was 61%. ST101 was the most common ST and accounted for 68 (59%) of the ColR-Kp. The 30 day mortality rate in patients with these isolates was 72%. In ST101, 94% (64/68) of the isolates had an altered mgrB gene, whereas the alteration occurred in 40% (19/47) of non-ST101 isolates. The OXA-48 and NDM-1 carbapenemases were found in 93 (81%) and 22 (19%) of the total 115 isolates, respectively. In multivariate analysis for the prediction of 30 day mortality, ST101 (OR 3.4, CI 1.46-8.15, P = 0.005) and ICU stay (OR 7.4, CI 2.23-29.61, P = 0.002) were found to be significantly associated covariates. Conclusions: Besides ICU stay, ST101 was found to be a significant independent predictor of patient mortality among those infected with ColR-Kp. A significant association was detected between ST101 and OXA-48. ST101 may become a global threat in the dissemination of colistin resistance and the increased morbidity and mortality of K. pneumoniae infection.

Emerging Escherichia coli O25b/ST131 clone predicts treatment failure in urinary tract infections.

BACKGROUND: We described the clinical predictive role of emerging Escherichia coli O25b/sequence type 131 (ST131) in treatment failure of urinary tract infection. METHODS: In this prospective observational cohort study, the outpatients with acute cystitis with isolation of E. coli in their urine cultures were assessed. All the patients were followed up for clinical cure after 10 days of treatment. Detection of the E. coli O25:H4/ST131 clone was performed by multiplex polymerase chain reaction (PCR) for phylogroup typing and using PCR with primers for O25b rfb and allele 3 of the pabB gene. RESULTS: In a cohort of patients with diagnosis of acute urinary cystitis, 294 patients whose urine cultures were positive with a growth of >10(4) colony-forming units/mL of E. coli were included in the study. In empiric therapy, ciprofloxacin was the first choice of drug (27%), followed by phosphomycin (23%), trimethoprim-sulfamethoxazole (TMP-SMX) (9%), and cefuroxime (7%). The resistance rate was 39% against ciprofloxacin, 44% against TMP-SMX, and 25% against cefuroxime. Thirty-five of 294 (12%) isolates were typed under the O25/ST131 clone. The clinical cure rate was 85% after the treatment. In multivariate analysis, detection of the O25/ST131 clone (odds ratio [OR], 4; 95% confidence interval [CI], 1.51-10.93; P = .005) and diabetes mellitus (OR, 2.1; 95% CI, .99-4.79; P = .05) were found to be significant risk factors for the treatment failure. In another multivariate analysis performed among quinolone-resistant isolates, treatment failure was 3 times more common among the patients who were infected with ST131 E. coli (OR, 3; 95% CI, 1.27-7.4; P = .012). CONCLUSIONS: In urinary tract infections, the E. coli ST131 clone seems to be a consistent predictor of treatment failure.

Molecular epidemiology of bloodstream-associated Escherichia coli ST131 H30-Rx subclone infection in a region with high quinolone resistance.

Bloodstream infections caused by Escherichia coli ST131 and ST131 H30-Rx subclones have emerged worldwide. This study was carried out to evaluate the prevalence of the ST131-Rx subclone and characterize the virulence properties of the Rx isolates among the bloodstream E. coli isolates. A total of 297 non-duplicated E. coli bloodstream isolates were studied. Antibiotic susceptibilities were tested using the disc diffusion method. PCR amplification and sequencing was used to identify ST131 and H30-Rx, the virulence gene, the ß-lactamase and virotype. Quinolone resistance among bacteraemic E. coli strains was 51 %, and it was 98 % among E. coli ST131 isolates. The ST131 isolates accounted for 16 % (49) of all isolates and all ST131 isolates belonged to the extraintestinal pathogenic E. coli. The proportion of H30 subclone among the ST131 isolates was 98 %, and 75 % of H30 isolates belonged to the H30-Rx subclone. The prevalence of ST131 increased from 13 to 23 % in 4 years; however, there was a decrease in the ratio of H30-Rx infections. CTX-M-15 was detected in 85 % of ST131 and all of the H30-Rx isolates. The virulence genes associated with adhesion, cell protection, iron uptake and toxins (papA, iha, kpsMTII, iut and sat) were more common in ST131 than in non-ST131 isolates. Most of the ST131 and H30-Rx isolates were of the C virotype. All papA-positive isolates were in virotype C. The E. coli ST131 clone has increased rapidly among bloodstream isolates. However, a decrease in the proportion of the H30-Rx subclone in the quinolone-resistant population suggests the possibility of dissemination of other virulent and quinolone-resistant subclones in hospital settings.

The clinical impact of ST131 H30-Rx subclone in urinary tract infections due to multidrug-resistant Escherichia coli.

In this study, risk factors for ST131 H30 and H30-Rx subclones among urinary tract infections (UTIs) caused by multidrug-resistant (MDR) Escherichia coli were described. Urine samples were collected from consecutive outpatients registered to the outpatient clinics of Baskent University Hospital (Ankara, Turkey) with complaints of acute cystitis in 2011. A total of 107 MDR E. coli isolates were included in the study. Of the 107 isolates studied, 26 (24.3%) were typed as ST131 clone. Extended-spectrum ß-lactamase (ESBL)-producers accounted for 59 (55.1%) of the 107 isolates. Among the 59 ESBL-positive isolates, 18 (31%) were found to belong to the ST131 clone. Of the 18 ESBL-positive ST131 isolates, 17 (94%) were defined as H30 subclone, among which 16 (94%) represented the H30-Rx subclone. Among the 48 ESBL-negative isolates, 8 (17%) ST131 isolates were detected, 7 (88%) of which belonged to H30 subclone; 5 (71%) of the H30 subclone isolates were classified under H30-Rx subclone. In multivariate analysis, hospitalisation within last year was the only host risk factor associated with MDR E. coli ST131 H30-Rx subclone UTI (OR=3.5, 95% CI 1.04-12.17; P=0.042). CTX-M-15 production was found to be highly associated with the presence of ST131 H30-Rx subclone (OR=4.8, 95% CI 1.54-15.32; P=0.007). In conclusion, urinary MDR E. coli ST131 H30-Rx subclone was found to be important in the dissemination of MDR UTIs in the community. Approximately 20% of the MDR isolates were H30-Rx subclone. Infection with this subclone was found to be healthcare-associated.