Phenotypic and genetic analysis of the antibiotic resistance patterns in uropathogenic Escherichia coli strains

The purpose of this work is to characterize by phenotypic and genotypic analysis the antibiotic resistance patterns in 118 Escherichia (E.) coli strains isolated from urinary tract infections in patients with neurogenic bladder. The E. coli strains have shown high level resistance to aminopenicillins, ampicillin + sulbactam, amoxicillin clavulanate, tetracycline, followed by quinolone, carboxipenicillins, aminoglycosides and cotrimoxazole. Multiple resistance to beta-lactams, aminoglycosides, fluoroquinolones and cotrimoxazol has been registered with high frequency among the studied strains. The phenotypic screening tests for the presence of beta-lactamases, i.e. cefinase and double disk synergism test (DDST) indicated that 65,2% of the tested strains are producing typical beta-lactamases. The synergy test was positive for the strains resistant to clavulanic acid, but susceptible to sulbactam, proving that this inhibitor is more sensitive for this test. Our study indicated a good correlation between the results obtained with DDST and E-test ESBL which confirmed the production of beta-lactamases in strains exhibiting synergism aspects in double disk diffusion test. The IEF analysis of the cellular sonicates revealed the presence of TEM pI 5,2; CTX-M pI 7,5; AmpC pI >= 8; SHV pI 7-8. The genotypic analysis by PCR and sequencing showed the presence of bla TEM and group 1 CTX-M genes in 75% of E. coli strains isolated from patients with neurogenic bladder.