High frequency of broad-spectrum β-lactamase-producing Klebsiella pneumoniae and E. coli isolated from urine of male patients


Urinary tract infections (UTIs) are the most common bacterial infections in the world and are common in general clinical practice (1, 2). The infection was initially diagnosed by the presence of at least 105 colony forming units (CFUs) of a single urinary pathogen in the urine sample. However, in recent years, the cutoff limit has been lowered due to bacterial counts of 103 and above and 102 CFU / ml (2, 3). UTI accounts for 25% to 40% of nosocomial infections and about 80% of cases associated with the use of urethral catheters (4, 5).

E. coli and Klebsiella pneumoniae are the major causative agents of Gram-negative bacteriuria in both hospital and community-acquired UTIs (2, 6). A broad spectrum of β-lactamase (ESBL) that produces E. coli and Klebsiella pneumoniae is a new cause of UTI worldwide and is often resistant to commonly prescribed antibiotics (7, 8). Outbreak of ESBL in E. coli and K. Iran’s pneumonia was found in 21% -56% and 12% -69.7%, respectively (9-15). TEM and CTX-M are the most common types of ESBL in the world. Phylogenetically, the CTX-M enzyme is divided into five major groups based on amino acid similarity: the CTX-M-1 group (CTX-M-1, -3, -10, -11,- 12, -15, -28 and FEC-1), CTX-M-2 group (CTX-M-2, -4, -5, -6, -7, -20 and TOHO-1), CTX-M- 8 groups (CTX-M-8), CTX-M-25 groups (CTXM-25 and -26) and CTX-M-9 groups (CTX-M-9, -13, -14, -16, -17, -19, -21, -24, -27 and TOHO-2). The abnormal spread of the blaCTX-M gene to mobile genetic elements such as plasmids and transposons is called the CTX-M pandemic worldwide (16). In particular, the development of co-resistance to aminoglycosides and fluoroquinolones has been observed in organisms that produce CTX-M (17, 18). This study focused on the prevalence of multidrug resistance in clinical strains of ESBL-producing E. coli and K. pneumoniae in hospitals in Teheran, and the molecular properties of several ESBL genes focusing on gender prevalence. Was carried out to evaluate.

Study Findings

Background: The number of wide-spectrum beta-lactamase-producing Enterobacteriaceae (ESBLs) reported worldwide continues to grow faster than other resistance mechanisms, especially in E. coli and Klebsiella pneumoniae.

Objective: This cross-sectional study is designed to determine the prevalence of multidrug resistance in E. coli and K. Pneumonia collected in a hospital in Tehran, and the molecular properties of some ESBL genes with an emphasis on the incidence of gender.

Materials and Methods: From 2009 to 2010, a total of 190 strains of E. coli and K. pneumoniae were collected from urine samples from patients in a hospital in Tehran, Iran, antibiotic sensitivity, ESBL phenotype, blaCTX- I investigated the existence of. M. and blaTEM genes. The minimum inhibitory concentration (MIC) of ceftazidime and cefotaxime was obtained by agar dilution.

RESULTS: 55.5% of E. coli isolates and 46.4% of K.pneumoniae isolates had the ESBN phenotype. The presence of blaCTX-M-1 was predominant in both organisms. Outbreak of blaCTX-M-1 carrier isolate under K. Pneumonia and E. coli were 49.1% and 85.7%, respectively. Of the ESBL-producing isolates, E. 68.5% of coli isolates and 59.3% of K. pneumoniae isolates carry the blaTEM gene, and simultaneous transport of BlaCTX-M and blaTEM occurred in 68.5% of E. 33.3% of Kori and K. pneumoniae strains. Tolerance to ceftazidime, cefotaxime, and cefepime was significantly higher in K. pneumoniae and E. coli isolated from urine samples from male patients. Significantly higher proportions of the blaCTX-M-1, blaTEM and co-blaCTX-M-1-blaTEM genes were observed in E. coli and K. pneumoniae isolates in the urine of male patients.

Conclusion: The results show that ESBL rates are high in E. coli and K. Pneumonia in a hospital in Tehran. In addition, this study shows that urine isolates from male patients are significantly more tolerant than female isolates.


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