Antibiotic resistance pattern in bacterial isolates obtained from frozen food samples of animal origin in Sanandaj and Ahvaz

1 School of Health, Environmental Health Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran. 2 Department of Pathobiology, Alborz University of Medical Sciences, Karaj, Iran. 3 Department of Microbiology, School of Medicine, Infectious and Tropical Diseases Research Center, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. 4 Department of Microbiology, School of Medicine, Kurdistan University of Medical Sciences, Sanandaj, Iran. 5 Food and Drug Deputy, Kurdistan University of Medical Sciences, Sanandaj, Iran.


INTRODUCTION
There is an increasing trend in production and consumption of meat, poultry meat, fish and their products.This, of course, requires adequate control and inspection both during poultry rearing and in slaughterhouses, processing plants and shops.Consumers are also a link in the chain of food-borne human diseases, because of the way they store and cook meat, poultry meat, fish and their products (Kozacinski et al., 2006;Lei et al., 2008).Therefore, microbial safety of food is a significant concern of consumers and industries today.
The rapid and accurate identification of food-borne pathogenic bacteria in food is important; both for quality assurance and to trace pathogens within the food supply (Kye et al., 2008;Hyun-Joong et al., 2008).Major foodborne pathogens include Bacillus cereus, Listeria  (Laboratório, 2006).Some of these foodborne pathogens can cause life-threatening diseases to humans and animals.Whilst all are well recognized, some are considered emerging because they have recently become more common.
In addition, food contamination with antibiotic resistant bacteria could be a major threat to public health as the antibiotic resistance determinants can be transferred to other pathogenic bacteria, causing compromise in the treatment of severe infections.The prevalence of antimicrobial resistance among food-borne pathogens has increased during recent decades (Boerlin et al., 2005;Choi et al., 2001).Therefore, this study aimed to determine the antibiotic resistance pattern in bacterial isolates obtained from frozen food samples of animal origin in Sanandaj and Ahvaz.

MATERIALS AND METHODS
A total of 250 packages of food of animal origin consisting of frozen chicken, chicken nuggets, frozen fish, mince, and beef burger were purchased from different separate grocery stores in Sanandaj and Ahvaz during one year.Field personnel collected the samples on a weekly basis.Retail samples was sealed in a plastic bag, labeled with a unique identifying number, and placed into a cooler with ice packs.Field personnel transport the specimens to food and drug laboratory, within 1 h of collection.
Antibiogram results clearly showed that resistance to Tetracycline and Ampicillin was 55 and 50% respectively.We also observed resistance to Chloramphenicol, and Erythromycin (Table 3).Similarly, Ahvaz results are as follows: out of 125 food samples, 71 (56.8%) were contaminated.A total of 76 bacteria were isolated and identified.Prevalence of E. coli, Salmonella Spp, and Proteus Spp, were 52, 03.2 and 02.4% respectively.The above bacteria were 39 and 26% resistance to Ampicillin and Tetracycline respectively.

DISCUSSION
A major goal for the food processing industry is to provide safe, wholesome and acceptable food to the consumer.Control of microorganisms is essential to meeting this goal.Many food pathogenic and spoilage bacteria are able to attach to food and remain viable even after cleaning and disinfection.This can seriously affect the quality and safety of the food processed and pose a potential risk to the consumer (Bagge-Ravn et al., 2003).
The present study demonstrated that three major enteric bacterial taxa were present in frozen food samples of animal origin obtained from supermarkets in the Sanandaj and Ahvaz.The findings presented herein suggest that there was not much a significant difference in the occurrence of bacteria among the evaluated food samples.The most prevalent bacteria in both the cities were E. coli.A study performed in the Washington, D.C reported E. coli prevalence of 38.7% in poultry (Cuiwei et al., 2001), which is much lesser to the results of the present survey.Several studies have shown that E. coli O157:H7 and other STEC are present in meat products, mostly beef products (Brooks et al., 2001;Heuvelink et al., 1996;Samadpour et al., 1994).
As regards antibiotic resistance, 55 and 50% of the bacterial strains which isolated from Sanandaj were resistant to Tetracycline and Ampicillin respectively.Many studies have reported almost same results concerning Tetracycline and Ampicillin resistant (Soltan et al., 2007;Bywater and Deluyker, 2004).Similarly, Tansuphasiri et al. (2006), evaluated 239 isolates of enterococci (113 from frozen foods and 126 from environmental water) for their resistance to 8 antibiotics by agar disk diffusion method.Most isolates from both sources were resistant to tetracycline (64.1% food strains; 46.8% water strains) and ciprofloxacin (53.4% food strains; 48.4% water strains).A relatively high prevalence of chloramphenicol, trimethoprimsulfamethoxazole and vancomycin resistance was present, ranging from 9.7 to 27.2% for food strains and 10.3 to 15.9% for water strains.
A recent study reported that the prevalence of antimicrobial resistance in commensal microflora is very useful in monitoring and understanding the process of antimicrobial-mediated selection in a population (Caprioli et al., 2000).The previous studies on resistance from developing countries have concentrated on pathogenic bacteria (Byarugaba et al., 2005;Kassa et al., 2007), but our study lead to isolation of one important resistance indicator; E. coli.
Bacteria were isolated and identified based on Institute of Standards and Industrial Research of Iran.Antibiogram was done using the agar disc diffusion method on Muller-Hinton agar (Merck, Germany), according to CLSI (Clinical and Laboratory Standards Institute, 2010).

Table 1 .
Prevalence of bacterial contamination of frozen food samples in Ahvaz and Sanandaj.

Table 3 .
Overall resistance of bacterial isolates from the frozen food samples of animal origin in Ahvaz and Sanandaj against different antibiotics.