Background: Gram Negative bacilli (GNB) are the most common causes of urinary tract infections (UTIs). There is a worrying level of antimicrobial resistance emerging in UTIs pathogens. Metallo-β-lactamases (MBLs) are rapidly spreading β-lactamases with no available FDA approved inhibitor conferring resistance to most β-lactam antibiotics including carbapenems. We aimed to determine prevalence and antimicrobial resistance patterns of Gram-negative uropathogens in our tertiary care hospital, and to characterize MBLs production among them.
Methods: A hundred and forty-three urine samples were collected from the Urology Department. Uropathogens were isolated on Cystiene Lactose Electrolyte Deficient agar and Mac-Conkey's agar. GNB were identified by conventional methods. Antimicrobial susceptibility was evaluated by disc diffusion method. Carbapenems resistant Gram-negative bacilli (CRGNB) were tested for MBLs production both phenotypically and genotypically.
Results: Eighty-five GNB (75.9%) were isolated from 112 positive cultures. Escherichia coli (49.4%) was the most prevalent isolate. Most of GNB showed high resistance patterns to various antimicrobials. Twenty-nine GNB isolates were resistant to at least one carbapenem (28.2% for imipenem, 30.6% for meropenem). Twenty-three isolates (79.3%) were phenotypically positive for MBL activity by combined disc test (CDT). Twenty-two isolates (75.9%) were positive for one or more of MBL genes (blaIMP, blaVIM and/or blaNDM).
Conclusions: Our study emphasized on the alarming rates of resistance to most of the common antimicrobials particularly carbapenems among GNB uropathogens, which represent a public health threat. CRGNB isolates in our hospital are phenotypically and genotypically associated with MBLs production so an effective strategy to combat these strains is mandatory.