Kinolon Dirençli ve Duyarlı İnvaziv Escherichia Coli Kan İzolatlarında St131/H30 Klon/Subklonunun Virülans ile İlişkisi

Abstract

Gürpınar Ö., Correlation Between ST131/H30 Clone/Subclone and The Virulence in Fluoroquinolone Resistant and Sensitive Invasive Blood Isolates of Escherichia coli, Hacettepe Un¬vers¬ty Inst¬tute of Health Sc¬ences Microbiology Master of Science Thes¬is, Ankara, 2018. Escherichia coli sequence type 131 (ST131) is a worldwide pandemic clone, causing predominant antimicrobial resistant infections. Subsequent researches have confirmed a worldwide spread of E. coli ST131 clone harbouring broad range of virulence and antibiotic resistance genes. A high prevalence of the clone has been identified in fluoroquinolone resistant E. coli isolates. Geographical distribution of the clone in Asia and the Middle East is very limited and little is known about the ST131 clone in many parts of the developing world. It has not known if there are certain virulence factors those make this ST131 clone such a successful pathogen. This study included all E. coli invasive blood isolates of hospitalized patients during one year period between January-December 2015 in Hacettepe University Hospitals and aimed to determine the antimicrobial susceptibility, molecular detection of antimicrobial resistance genes and virulence factors, and the frequency of ST131/H30 clone/subclones. Antimicrobial susceptibility testing and phenotypic tests of extended spectrum beta-lactamases and carbapenemases of E. coli blood isolates were performed and interpreted in accordance with the CLSI and EUCAST criteria. Distribution of acquired antimicrobial resistance genes; blaCTX-M, blaCTX-M-15, blaKPC, blaNDM, blaIMP, blaOXA-48 and ST131/H30 clone/subclone and virulence genes were defined using polymerase chain reaction. The mean age of 152 patients was 60.3±18.6 and the mean hospitalization time was 25.9±35.1. Distribution of patients according to the services were emergency services (n=63), intensive care unit (n=29), bone marrow transplantation unit (n=3), oncology unit (n=25), surgical services (n=20) and internal medicine services (n=26). The rate of hospital-acquired E. coli infections was 53.3%, mortality was 42%, malignancy was 59.9%. Antibiotic usage rate before bacteremia was 46.1%. Beta lactam/beta-lactamase inhibitors were used in 24.3%, carbapenems in 14.5% and fluoroquinolones in 13.1% of the patients. Urinary and central venous catheterization rate was 36.8% and 20.4% among patients. Antimicrobial resistance rates for SAM, GEN, AMP, CRO, TMP-SMX, CAZ, CTX and CIP were as 23%, 32%, 65%, 23.5%, 37%, 7.7%, 12% and 53.5%, respectively. All isolates were susceptible to IMP and ERT.ST131 was found in 156 (99.4%) and H30 subclone in 111 (70.7%). Among 53.5% ESBL positive isolates, 49.7% were blaCTX-M positive and 45.2% were blaCTX-M-15. Of the CTX-M-15 positive isolates, 97.2% were identified as H30Rx positive. The predominant carbapenemase was blaOXA-48 (21%), followed by blaNDM-1 (1.3%) and blaVIM (3.2%). There was no blaKPC and blaIMP production. Virulence genes ompT (82.2%), iutA (73.2%), usp (64.3%) and papA (22.9%) were common in ST131 isolates. This study showed that the presence of ST131 was high in E. coli bloodstream isolates in our hospital. ST131-infected patients were frequently immunosuppressed with a long history of hospitalization and antibiotic intake prior to bacteremia was high in these patients. blaOXA-48 was the most common carbapenemase; ompT and iutA were the most common virulence genes in ST131 isolates. In conclusion, ST131 clone, in particular the H30Rx subclone showed prominent resistance to fluoroquinolones due to CTX-M-15 type ESBL production. Finding out a parameter to detect virulant clones of E. coli in invasive blood isolates may cause to control drug resistant E. coli infections and may also cause to set more rational antibiotic strategies in empirical therapy of these infections.