Analysis of the drug-resistant characteristics of Klebsiella pneumoniae isolated from the respiratory tract and CTX-M ESBL genes

Abstract

ABSTRACT. The main aim of this study was to understand the relationship between the drug-resistant characteristics of Klebsiella pneumoniae and CTX-M-type extended spectrum β-lactamases (ESBLs), and to detect the distributions of CTX-M-type ESBLs in clinically isolated strains. CTX-M ESBL genes isolated from the clinical samples were amplified by polymerase chain reaction and identified by sequence analysis; the antibiotic susceptibility of the samples was determined using the Kirby-Bauer disc-diffusion method. One hundred and five strains among the 246 isolated strains of K. pneumoniae tested positive for ESBL production (42.68%); 92 of these produced CTX-M ESBLs. Of the 92 CTX-M ESBL strains, 81 produced CTX-M-1 ESBLs and 11 produced CTX-M-25 ESBLs. Fifty-seven of the CTX-M-1 ESBL-and six of the CTX-M-25 ESBL-producing bacteria had CTX-M ESBL genes that coexisted in the plasmid and chromosome. The KirbyBauer antibiotic susceptibility method revealed that CTX-M ESBLpositive strains showed a higher rate of resistance to cefazolin, cefoxitin, cefuroxime, ceftazidime, cefotaxime, aztreonam, levofloxacin, and 12044 S.Y. Huang et al. ©FUNPEC-RP www.funpecrp.com.br Genetics and Molecular Research 14 (4): 12043-12048 (2015) cotrimoxazole, compared to the CTX-M ESBL-negative strains (P < 0.05). The CTX-M ESBL genes were commonly observed in the K. pneumoniae isolated from respiratory tract samples; these were significantly associated with the drug-resistant characteristics of K. pneumoniae to β-lactam antibiotics.

Antimicrobial Resistance Profile of Different Clinical Isolates against Third-Generation Cephalosporins

“…However, it is dissimilar with other studies which showed that the isolates exhibited similar resistance pattern to both ceftazidime and ceftriaxone [ 28 , 29 ]. It was also reported that Klebsiella pneumoniae strain isolated from patients with community acquired pneumonia was resistant to third-generation cephalosporins [ 30 , 31 ]. This is because these strains have a β -lactam ring provided with a Zwitterionic structure that protects these antibiotics from hydrolysis by β -lactamases [ 32 ].…”

Emergence and molecular characterization of multidrug-resistant <em>Klebsiella pneumoniae</em> isolates harboring <em>bla</em>_CTX-M-15 extended-spectrum &beta;-lactamases causing ventilator-associated pneumonia in China

“…Over the past decade, predominant CTX-M-type ESBLs have been described globally, including China, South Korea, and many other countries 11,31,32. In fact, together with bla CTX-M-14 , bla CTX-M-15 is currently the most common variant detected worldwide in clinically important Gram-negative bacteria 33,34.…”

The Antimicrobial Susceptibility of Klebsiella pneumoniae from Community Settings in Taiwan, a Trend Analysis

“…Finally, the actual location of the ESBL and AmpC β-lactamase genes were not determined in our study. Although it has been shown that ESBL genes could reside on the chromosome40, several studies on ESBL-producing K. pneumoniae have found CTX-M-type and SHV-type ESBL genes to be mostly located on plasmids41424344. Furthermore, the great genotypic diversity of our ESBL and/or AmpC β-lactamase-producers, having different combinations of ESBL/AmpC β-lactamase genes even among isolates within the same PFGE cluster, implied that these resistant genes are acquired through transfer of plasmids among isolates of different genetic backgrounds.…”