No abstract

Our results showed a correlation between presence of virulence gene and antibiotic resistance in K. pneumoniae.

ScienceKlebsiella pneumoniae (K. pneumoniae) is one of the most common causes of nosocomial and opportunistic infections. This microorganism is involved in pneumonia, bacteremia, septicemia, diarrhea, wound infections, and infections of the urinary tract, bones, joints, and central nervous system. 1 The spread of extended-spectrum β-lactamase (ESBL) producing K. pneumoniae infections is an increasing public health problem internationally. ESBLcarrying microorganisms are resistant to third-generation cephalosporin antibiotics and have cross-resistance to aminoglycosides and quinolones. [2][3][4] CTX-M β-lactamases are the most prevalent types of ESBL worldwide. Phylogenetically, these enzymes have been classified into 5 major groups based on their amino acid sequence similarities: the CTX-M-1 cluster (CTX-M-1, -3, -10, -11, -12, -15, and -28, as well as FEC-1), the CTX-M-2 cluster (CTX-M-2, -4, -5, -6, -7, and -20, as well as TOHO-1), the CTX-M-8 cluster (CTX-M-8), the CTX-M-25 cluster , and the CTX-M-9 cluster (and -27, as well as TOHO-2). 5-7 The primary mechanism of resistance to aminoglycosides is the expression of aminoglycoside-modifying enzymes. ABSTRACTObjective: To determine the prevalence of extended-spectrum beta lactamases (ESBLs), the bla CTX-M genes, and aminoglycoside modifying enzymes genes in clinical isolates of Klebsiella pneumoniae (K. pneumoniae).Methods: We collected 200 nonduplicate clinical isolates of K. pneumoniae in hospitals in Tehran, Iran. We determined antibacterial susceptibility and confirmed ESBL production via the disk diffusion and minimum inhibitory concentration (MIC) methods. We identified bla CTX-M and aminoglycoside modifying enzymes genes via polymerase chain reaction (PCR). Results:We detected 72 (36.0%) ESBL-positive K. pneumoniae, in which the bla CTX-M-15 was dominant (62.5%). A total of 54.0% of isolates were resistant to at least 1 tested aminoglycoside; also, we detected aac(6')-Ib in 42.5% of isolates and aac(3)-IIa in 35.1% of them. We observed a high rate of aminoglycoside-resistant genes (71.0%) among bla CTX-M-15 -carrying isolates. Conclusion:We report that CTX-M-15 is the dominant type of CTX-M, which associates with entities that have high aminoglycoside resistance. Continuous surveillance and monitoring of this entity are needed because the codissemination of multiple drug-resistant genes with K. pneumoniae may become a serious therapeutic problem.

Escherichia coli is the major causative pathogen of urinary tract infection (UTI) in humans. Virulence and drug resistance play important roles in the pathogenesis of E. coli infections. The aims were to investigate the presence of uropathogenic virulence genes and to evaluate a relationship between antibiotic resistance and virulence in E. coli from UTI. A total of 132 E. coli were collected between April and June 2015 in two hospitals of Sanandaj, Iran. Isolates were examined for susceptibility to 16 antibiotic disks using the disk diffusion method and for possession of virulence genes by polymerase chain reaction. Associations between antimicrobial resistance and virulence genes were investigated. A P < 0.05 was considered significant. Of the 132 isolates, the most prevalent virulence gene was pap (31.1%), followed by cnf (28.8%), hly (16.7%), and afa (10.6%). Different patterns of virulence genes were identified. A significant association was detected between the simultaneous presence of hly and pap. The most effective antibiotics were nitrofurantoin, cefoxitin, and imipenem and the least effective were ampicillin, trimethoprim-sulfamethoxazole, and cefotaxime. An association was seen between the presence of cnf and susceptibility to the certain antibiotics, whereas strains with a reduced susceptibility to the certain antibiotics were associated with a significantly increased prevalence of afa and hly (P < 0.05). These findings suggest a correlation between the presence of virulence gene and resistance in E. coli strains from UTI. The results indicate that there is a need for surveillance programs to monitor drug resistance in pathogenic E. coli.

Background: CTX-M-type β-lactamases are increasingly becoming the predominant ESBLs globally in recent years. Integrons are genetic elements which can integrate gene cassettes, usually antibiotic resistance genes. Objectives: The aims were to determine antibiotic susceptibility and to detect genes encoding CTX-M-1 group enzymes and class 1, 2, and 3 integrons among the Klebsiella pneumoniae isolated from children in Tehran hospitals, Iran. Patients and Methods: Thirty-one K. pneumoniae isolates were collected from samples of children aged 0-12 years admitted to three hospitals in Tehran between May and December 2011, and identified using biochemical tests and PCR. Susceptibility of isolates to 14 antibiotic disks was determined using disk diffusion method. The combined disk method was used for the detection of ESBL. The presence of bla CTX-M-1 group and class 1, 2, and 3 integrons was investigated by PCR. Results: Most of the isolates showed high level of resistance: 17 isolates were simultaneously resistant to Amoxicillin-Clavulanic acid, Cefotaxime, Ceftriaxone, Aztreonam, and Ceftazidime (17/31, 54.9%). All were susceptible to Imipenem and Ciprofloxacin. ESBL production was detected in 54.9% (17/31). The bla CTX-M-1 group was detected in all Cefotaxime-resistant isolates (17/31, 54.9%). Class 1 integron was detected in 8 isolates (25.8%). The class 2 and 3 integrons were not detected. Conclusions: The results showed that the CTX-M-1-producing K. pneumoniae is already present in some parts of Tehran. The presence of class I integron genes among resistant strains of K. pneumoniae highlights the continued monitoring of drug resistance in clinical settings.