Dissemination and characteristics of Klebsiella spp. at the processed cheese plant

Abstract

The genus Klebsiella is not generally considered as a major foodborne pathogen and with regard to food production it represents also a hygiene indicator. This study was focused on the monitoring of Klebsiella spp. dissemination at the processed cheese plant and determination of virulence determinants and antibiotic resistance of obtained strains. Klebsiella spp. were detected in 43% (37/87) of samples: swabs from the cheese processing environment (34/69), personnel (2/3) and raw material (milk powder) from an opened packaging (1/7). All tested samples of final processed cheeses were negative for the presence of Klebsiella spp. Obtained strains were identified as K. oxytoca (n = 32) and K. pneumoniae (n = 23). Typing results enabled to reveal the presence of two predominant PFGE clusters of K. pneumoniae and K. oxytoca suggesting the occurrence of suspect persistent strains, and spread of Klebsiella spp. between the production environment and the personnel. The melting process of processed cheese production was able to eliminate Klebsiella spp. in the final products, although some K. oxytoca and K. pneumoniae strains carried genes of the locus of heat resistance 1 (LHR1), which may lead to their increased heat resistance. K. pneumoniae and K. oxytoca isolated from the processed cheese plant did not represent any hypervirulent or multidrug-resistant strains which could be a potential threat to public health.