Relationships between Virulence Factors and Antimicrobial Resistance among Escherichia coli Isolated from Urinary Tract Infections and Commensal Isolates in Tehran, Iran

OBJECTIVES: Uropathogenic Escherichia coli (UPEC) are the major cause of urinary tract infections (UTIs). Here, we determined whether sensitivity to antibiotics was related to the prevalence of iron scavenging genes, or to biofilm and hemolysis formation. METHODS: A total of 110 UPEC and 30 E coli isolates were collected from the urine of UTI patients and feces of healthy individuals without UTI, respectively. The presence of iron receptor genes and phenotypic properties were evaluated by polymerase chain reaction and phenotypic methods, respectively. Susceptibility to routine antibiotics was evaluated using the disc diffusion method. RESULTS: The prevalence of iron scavenging genes ranged from 21.8% (ireA) to 84.5% (chuA) in the UPEC. Resistance to ceftazidime and cefotaxime was significantly correlated with the presence of fyuA and iutA iron genes. Biofilm production was significantly associated with the prevalence of fyuA and hma iron genes. A higher degree of antibiotic resistance was exhibited by isolates that produced biofilms than by their non-biofilm producing counterparts. CONCLUSION: Our study clearly indicates that biofilm production is associated with antibiotic resistance, and that iron receptors and hemolysin production also contribute to reduced antibiotic sensitivity. These results further our understanding of the role that these virulence factors play during UPEC pathogenesis, which in turn may be valuable for the development of novel treatment strategies against UTIs.

Evaluation of prevalence, homology and immunogenicity of dispersin among enteroaggregative Escherichia coli isolates from Iran

Background: Diarrhea, caused by enteroaggregative Escherichia coli [EAEC], is an important infection leading toillness and death. Numerous virulent factors have been described in EAEC. However, their prevalence was highly variable among EAECs of distinct geographic locations. Studies have shown that dispersin [antiaggregation protein, aap] is one of the important and abundant virulent factors in EAEC. In this study, we aimed to determine the presence, conservation, and immunogenicity of aap gene in EAEC isolated from Iranian patients

Methods: PCR amplification of aap gene in the EAEC isolates was performed, and the aap gene was cloned in pBAD-gIIIA vector. The sequence of aap gene was analyzed using the ExPASy and BLAST tools. The expression of aap gene was performed in E. coli Top10, and expression confirmation was carried out by SDS-PAGE and Western-blot techniques. Rabbits were immunized with purified dispersin protein emulsified with Freund's adjuvant. Sera were collected and examined for antibody response. Finally, in vitro efficacy of dispersin and anti-dispersin was evaluated

Results: The results of PCR showed the presence of aap gene in all of the EAEC isolates with significant homology. Finally, the significant difference between the levels of IgG response in dispersin-injected rabbits and control group was observed

Conclusion: Our results were in accordance with other studies that reported the presence of dispersin in the EAEC isolates with high conservation and immunogenicity. Hence, dispersin could be a promising candidate for any probable prevention against EAEC infections

Metallo- beta-lactamases among multidrug resistant [MDR] gram negative bacteria isolated from clinical specimens during 2009 in Sanandaj, Kurdistan province

Today, there are numerous reports about emerging multi drug resistant gram negative bacteria all around the world, especially in ICUs. Rarely, Metallo-beta-lactamase [MBL] enzymes are responsible for these cases. Study of MBLs for diagnosing and preventing distribution of the origin of infection are critical issues. In addition, we would like to compare the efficacy of Iranian and foreign- made antibiotic disks. During 2009 all entered clinical specimens to the laboratory tested for detecting gram negative bacteria. Isolated bacteria were tested by Kirby-Bauer method to antibiotic susceptibility test by Iranian and foreign [MAST] disks. For gram negative carbapenem resistant isolates, PCR technique used to detect VIM, GIM, and SIM variants of MBLs. During one year, 17890 clinical specimens referred Besat laboratory. The most specimen was Urine [8172] followed by blood culture [5190] that in which 1110 gram negative and positives isolated. Out of which, 778 [70%] of isolates were gram negatives. MDR gram negatives were 157 [20.2%]. Imipenem and meropenem were the most efficient antibiotics [all susceptible] and ceftriaxone was the least [19% susceptible]. E. coli was the most prevalent isolate. 79 Gram negative isolates [10.1%] were resistant to Iranian-made discs but all susceptible for foreign ones. All 79 isolates were tested by PCR for MBL genes, that, all were negative. Besides, Iranian imipenem and cefepime disks have had distinguishable difference in susceptibility of isolates. Fortunately, none of gram negative isolates were MBL producer, which revealed no colonization of MBL producing bacteria. Iranian-made disks appear efficient except for imipenem and cefepime.