Egyptian Journal of Medical Microbiology, January 2010 Vol. 19, No. 1 27 Antimicrobial Resistance Genes and Some Virulence Factors in Escherichia coli and Streptococcus pyogenes Isolated from Mansoura University Hospitals Ramadan Hassan, Rasha Barwa and Hanan R. Shehata Department of Microbiology, Faculty of Pharmacy, Mansoura University, Mansoura, Egypt, ABSTRACT Aim: The present study aims to determine the antimicrobial resistance genes and some virulence factors produced by clinical isolates of E. coli and S. pyogenes isolated from different sources. Methods: A total of 60 E. coli and 42 S. pyogenes were studied for antibiotic susceptibility pattern, resistance genes, different resistance enzymes production and some virulence factors such as serum resistance, haemolysin, bacterial ability for colonization, haemagglutination , gelatinase, streptokinase and streptodornase. Results: Nearly 79.4 % of the isolates are multiple resistant as they were resistant to all antimicrobial classes used in this study. All E. coli isolates and only 2 S. pyogenes were β-lactamase producers. Detection of bla-TEM gene reveled that it was amplified on plasmid DNA of 23 isolates out of 25 E. coli isolates. AGIEs prepared from 19 E. coli and 11 S. pyogenes isolates exhibited variable inactivation percentages on different aminoglycosides. Chloramphenicol acetyltransferase (CAT) enzyme was detected among 55% of E. coli isolates. Gyr A gene was successfully amplified by a specific primer set on plasmid DNA of 36 isolates out of 39 tested E. coli isolates which were quinolone resistant. bla-TEM gene was amplified on plasmid DNA of 23 isolates out of 25 B-lactam resistant E. coli isolates. While for S. pyogenes, Gyr A was detected and amplified on genomic DNA of 14 quinolone resistant isolates and bla-TEM was detected and amplified on genomic DNA of 28 B-lactam resistant isolates. Among 60 E. coli isolates, 42 (70%) were serum resistant, 20 (33.3%) showed mannose-resistant haemagglutination, 16 (26.7%) showed mannose-sensitive haemagglutination, 37 (61.7%) were slime producers, 10 (16.7%) were hemolytic and none of E. coli isolates was positive gelatinase producer. Among 42 S. pyogenes isolates, streptodornase production was detected in 28 (66.7%) of S. pyogenes isolates while streptokinase activity was detected in 23 (55%) of S. pyogenes isolates. INTRODUCTION The discovery and use of antibiotics has been one of the major scientific achievements of the 20 th century. During the early period of antibiotic usage, antibiotics were being used to cure potentially lethal infections. However, widespread antibiotic use has promoted the emergence of antibiotic-resistant pathogens, including multidrug resistant strains [1] . Antibiotic resistance is now well recognized as a major problem in the treatment of infections in hospitals and, with increasing and alarming frequency, in the community [2] . E. coli is one of the commensals in human intestinal tract. As commensals, it contributes to maintenance of health of a person. However, E. coli when enter into unnatural sites, can cause variety of infectious diseases such as urinary tract infections, wound infections, bacteraemiae, meningitis and other soft tissue infections [3] . The ability of E. coli to cause extraintestinal infections depends largely on several virulence factors, which help in the survival of E. coli under adverse conditions present in those sites [4] . Urinary tract infection (UTI) is one of the most prevalent bacterial infections, and the financial burden on family and society is substantial [5] . Uropathogenic Escherichia coli (UPEC) are the most common microorganisms causing UTIs. UPEC strains possess specialized virulence factors, enabling them to colonize and invade to the host, disrupt the host defense mechanisms, injure host tissues, and/or stimulate a noxious host inflammatory response. Virulence factors of recognized importance in the pathogenesis of UTI include diverse adhesins, toxins, siderophores, and polysaccharide coatings [6] . Because UPEC yearly affects a large proportion of the population, they are a major target of antimicrobial therapy. However, the clinical management of UTI is complicated by the increasing incidence of infections caused by