Phenotypic Detection of Virulence Factors of Uropathogenic Enterobacteriaceae

Abstract

Members of the family Enterobacteriaceae are the major cause of nosocomial infections, including approximately 70% of gastrointestinal infections, 60% to 70% of urinary tract infections (UTIs), and septicemias. Since 1990, members of Enterobacteriaceae have emerged as predominant pathogens causing UTIs. In this study, we performed phenotypic testing of the virulence factors in uropathogens. A total of 118 uropathogens belonging to the family Enterobacteriaceae were isolated from suspected UTI cases in patients aged > 18 years. Uropathogens were tested for virulence factors, such as hemolysin, phospholipase, gelatinase, and lipase production, as well as for mannose resistance, mannose-sensitive hemagglutination (MRHA, MSHA), serum resistance, and cell surface hydrophobicity. Among 118 uropathogenic Enterobacteriaceae isolates, E. coli was the most prevalent (62,52.5%), followed by Klebsiella (28,23.7%), Citrobacter (23,19.5%), and, Proteus species (5, 4.2%). Serum resistance was the most common virulence factor and was seen in 54(87%) of E. coli, 24 (85.7%) of Klebsiella species, 22 (95.7%) of Citrobacter species, and 5(100%) of Proteus species isolates. Furthermore, 10 (16.1%) isolates of E. coli showed mannose resistance hemagglutination and 7(11.3%) showed mannose-sensitive hemagglutination. Two (8.7%) isolates of Citrobacter species showed mannose resistance and mannose-sensitive hemagglutination. Hemolysis was observed in 33(53.2%) isolates of E. coli, 11(39.3%) of Klebsiella species, 15(65.2%) Citrobacter species, and 1(20%) Proteus isolate. Gelatinase production was observed in 14(22.6%) of E. coli, 6(21.4%) of Klebsiella species, 7(30.4%) of Citrobacter species, and 5(100%) of Proteus isolates. All E. coli, Klebsiella species, and Citrobacter species isolates tested negative for phospholipase. This study showed that the Enterobacteriaceae family plays a role in UTIs by evading the host immune response through the production of various virulence factors.