Abstract
This study aimed to assess the frequency of Klebsiella pneumoniae in food samples and to detect antibiotic resistance phenotypes, antimicrobial resistance genes and the molecular subtypes of the recovered isolates. A total of 998 food samples were collected, and 99 (9.9%) K. pneumoniae strains were isolated; the frequencies were 8.2% (4/49) in fresh raw seafood, 13.8% (26/188) in fresh raw chicken, 11.4% (34/297) in frozen raw food and 7.5% (35/464) in cooked food samples. Antimicrobial resistance was observed against 16 antimicrobials. The highest resistance rate was observed for ampicillin (92.3%), followed by tetracycline (31.3%), trimethoprim-sulfamethoxazole (18.2%), and chloramphenicol (10.1%). Two K. pneumoniae strains were identified as extended-spectrum β-lactamase (ESBL)–one strain had three beta-lactamases genes (blaSHV, blaCTX-M-1, and blaCTX-M-10) and one had only the blaSHV gene. Nineteen multidrug-resistant (MDR) strains were detected; the percentage of MDR strains in fresh raw chicken samples was significantly higher than in other sample types (P<0.05). Six of the 18 trimethoprim-sulfamethoxazole-resistant strains carried the folate pathway inhibitor gene (dhfr). Four isolates were screened by PCR for quinolone resistance genes; aac(6’)-Ib-cr, qnrB, qnrA and qnrS were detected. In addition, gyrA gene mutations such as T247A (Ser83Ile), C248T (Ser83Phe), and A260C (Asp87Ala) and a parC C240T (Ser80Ile) mutation were identified. Five isolates were screened for aminoglycosides resistance genes; aacA4, aacC2, and aadA1 were detected. Pulsed-field gel electrophoresis-based subtyping identified 91 different patterns. Our results indicate that food, especially fresh raw chicken, is a reservoir of antimicrobial-resistant K. pneumoniae, and the potential health risks posed by such strains should not be underestimated. Our results demonstrated high prevalence, antibiotic resistance rate and genetic diversity of K. pneumoniae in food in China. Improved control and prevention strategies are urgently needed.
Highlights
Klebsiella pneumoniae is a common opportunistic pathogen that causes human infections
In a previous survey conducted in the United States, 53 (16.1%) MDR K. pneumoniae strains were isolated from 330 farm-raised frozen shrimp that were imported from Thailand to the United States [9]
In another survey focusing on fresh vegetables in Spain, 9 K. pneumoniae strains were obtained from 160 vegetables, among which 1 (0.6%) was an MDR strain [8]
Summary
Klebsiella pneumoniae is a common opportunistic pathogen that causes human infections. It can be widely distributed in the respiratory and intestinal tracts of humans and animals and in a variety of environments and vectors. This pathogen can cause pneumonia, respiratory tract infections, urinary system infections, septicemia and other diseases [1,2]. Antimicrobials have been widely used to treat K. pneumoniae infections in humans. A recent report showed that foodborne K. pneumoniae could cause a nosocomial outbreak [11]. The potential contribution of K. pneumoniae to the resistance of clinically relevant bacteria is cause for concern
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