Dairy products are potential vehicles for microorganisms from the Enterobacteriaceae family, which can exhibit multi drug resistance to available antimicrobials, reduced susceptibility phenotypes to carbepenens, and produce biofilm, proteolytic enzymes, lipolytic enzymes, and antimicrobial substances, providing advantages for the bacteria in a competitive niche. All these factors represent potential risks to the health of consumers of dairy products, particularly immunocompromised consumers.
In the supply chain of dairy products like production lines, transport, and storage, good manufacturing practices and hygiene, as well as best practices in commercialization, must be followed mainly for products consumed without any prior processing. Additionally, the absence of pathogens, like Salmonella spp. and E. coli, does not indicate that the product is fit for consumption, since other potentially pathogenic bacteria of the same family may be present in the food. Thus, testing for Enterobacteriaceae, including species that are not yet assessed according to regulator standards, may offer a better view of the quality, sanitary conditions, and safety of dairy foods.
Bacterial antibiotic resistance has been recognized as a global problem in both the medical and agricultural fields. There is a worldwide concern about the increased prevalence of antimicrobial resistance in bacteria. Resistant bacteria reach the human population through a variety of pathways. Most studies have been focused on pathogenic microorganisms, that present immediate risks to human health but there is a growing interest in commensal components of the microbiota associated with food (Munsch-Alatossava et al., 2012). Observance of hygiene can play an important role in ensuring food safety and controlling the transmission of resistant bacteria from produce.
Our investigation shows neither coliforms nor the hygiene indicating bacteria, E. coli was not detected in any of the samples examined. Peda being a heat desiccated product, it will be free from gram negative fermentative heat sensitive bacteria when it was prepared. But subsequent handling and environmental factors result in a contaminated product. Prevalence of Salmonella and other pathogens such as E. coli, Shigella, hemolytic Streptococci and Pseudomonas aeruginosa in peda samples were reported by (Patel, 1984). Many of the opportunistic pathogens belonging to the Enterobacteriaceae were also detected in the peda samples. Their presence in the peda samples was significant as this food product is consumed by all age groups of the society. Enterobacter species are now increasingly encountered as causing nosocomial infections causing urinary tract infections and bacteremia. Enterobacter species namely, E. cloacae and E. gergoviae were detected in 16% of peda samples. Detection of E. gergoviae has been reported in environmental, cosmetics, and clinical samples, in France, Africa and USA (Richard et al., 1976); (Brenner et al., 1980). Our finding was the first report of prevalence and detection of E. gergoviae in a food sample. Y. bercovieri was isolated from 2 samples and Y. rohdei from one sample. Y. bercovieri, one among the eight new Y. enterocolitica-like species, was previously designated Y. enterocolitica biogroup 3B. It is known to produce the heat stable enterotoxin (Sulakvelidze et al., 1999).
Acinetobacter lwoffii, A. baumannii/calcoacetius, Pantoea agglomerans PA 2, K. pneumoniae subsp. pneumonia, C. sakazaki (E. sakazaki), Leclericia adecarboxylata and P. nematophilus were also detected in the peda samples. Acinetobacter was considered as a low-grade pathogen, (Joly-Guillou, 2005) reported the high pathogenicity and ability to cause invasive disease by the members of this genus. A. lwoffi, an opportunistic pathogen can survive for long periods under desiccated conditions (Houang et al., 1998). P. agglomerans, previously called as E. agglomerans, has been implicated in outbreaks of septicemia in the United States and Canada. Contamination of closures on bottles of infusion fluids was the source of the outbreaks (Delétoile et al., 2009). K. pneumoniae sub sp. pneumoniae is opportunistic pathogen that primarily attacks immunocompromised individuals and hospitalized patients (Podschun and Ullmann, 1998). R. terigena (formerly K. terigena) was isolated from 2 samples. C. sakazakii (E. sakazakii) was isolated from one sample. It has been linked with serious infections in infants, following the consumption of powdered infant formula (Joint and WHO, 2004; Mullane et al., 2007; Organization, 2006) known to have lowest aw. E. sakazakii infections have caused the preterm very low birth weight neonate with meningitis and infants with bacteraemia in India (Ray et al., 2007). Leclericia adecarboxylata isolated from peda sample is an opportunistic human pathogen that phenotypically resembles E. coli. But the biochemical characteristics like lysine decarboxylase, malonate assimilation, acid production from arabitol and cellobiose, but not from adonitol and sorbitol, allowed definitive separation of L. adecarboxylata from E. coli (Stock et al., 2004).
Even though E. coli and coliforms were not detected in the surveillance, Enterobacteriaceae forms were common. Antibiotic sensitivity studies on the isolates were conducted keeping in mind the prevalence of horizontal gene transfer among closely related bacteria. Bacterial antibiotic resistance has been recognized as a global problem in both the medical and agricultural fields. Most studies on antibiotic resistance have been focused on pathogenic microorganisms, that present immediate risks to human health but there is a growing interest in commensal components of the microbiota associated with food (Munsch-Alatossava et al., 2012).
Most of the isolates were susceptible to the fluoroquinones and aminoglycosides tested. Resistance to nalidixic acid was observed in some isolates. This antibiotic was historically used for treating urinary tract infections, caused by E. coli, Proteus, Shigella, Enterobacter and Klebsiella. It is no longer clinically used for this indication in the USA. Among the cephalosporins, 47% of the isolates were resistant to cefpodoxime, a third generation cephaolosporin. In the recent past, third generation cephalosporins have gained importance in the treatment of enteric fever. With regard to other antibiotics tested, 64.7% isolates to nitrofurantoin and 52.9% to augmentin were resistant. Thus it is of extreme importance to examine the specimens of apparently healthy dairy handlers to clarify their role in shedding bacterial pathogenic agents.
Uncleaned hands, poor quality of milk, unhygienic conditions of manufacturing unit, inferior quality of material used, water supplied for washing the utensils and post processing contamination might be the cause for the presence of enterobacteriaceae in peda samples.
The study reveals the absence of the top foodborne pathogens such as E. coli and coliforms from peda samples. Although E. coli and coliforms were not detected in any of the peda samples, the presence of other Enterobacteriaceae was confirmed by biochemical tests. Although E. gergoviae has been reported in environmental, cosmetics, and clinical samples, our finding was the first report of prevalence and detection in a food sample. Thus focusing attention on the safety of food processing, microbiological evaluation of peda samples revealed the presence of other Gram negative bacteria of clinical significance. The isolates also showed varying degree of resistance to antibiotics like nalidixic acid, cefoxitin, cefpodoxime, aztreonam, nitrofuratoin and augmentin. To the best of our knowledge, this is the first report of evaluating antimicrobial resistance in Enterobacteriaceae isolated from milk peda.
It is advised to the local vendors to keep in view the public health prominence of consumer; and the strict hygienic preventive measures should be practiced during pre and post-preparation handling, storage and marketing of the finished products. This will also increase the quality of the product. It is concluded from present findings that peda samples from organized dairy were superior to that of private and local vendors.