FOODBORNE ILLNESS

Campylobacter

Biofilms are communities of microorganisms that live attached to a surface, embedded in a protective extracellular matrix. Food presents a favourable substrate for biofilm formation because it provides nutrients and good environmental conditions for microorganisms to thrive. In addition, surfaces in the food industry are in constant contact with new foods that can bring nutrients and/or new microorganisms to a biofilm. Biofilms often show a high resistance to disinfection methods (e.g., antibiotics and chemical treatments) and are the cause of foodborne illnesses and food spoilage.

Non-thermal or cold atmospheric-pressure plasma (CAP) is being investigated as a new technology for the disinfection of thermally labile materials (including food) and food-contact surfaces. CAP consists of a mix of reactive chemical species and charged particles that have antibacterial activity. This chapter describes the use of CAP to eliminate biofilms and discusses examples of its application in the food industry.

This chapter focuses on chilled food microbiology. Chilled foods comprise a diverse and complex group of commodities that contain a large number of ingredients. The composition and number of micro-organisms present is affected by the indigenous microflora, micro-organisms contaminating before and after processing, the growth rates and abilities of the micro-organisms, the spoilage abilities of the micro-organisms, the intrinsic properties of the food, the effects of processing and packaging, and the time and temperatures of storage. Consequently, the microbial safety and spoilage of chilled foods is very complex, but certain general principles may be applied: (i) the microbiological status of all raw materials should be known and only materials of good quality used; (ii) all stages of processing should be defined, monitored and controlled to ensure their correct operation. This is of particular significance in foods that rely on a combination of factors to ensure microbial stability; (iii) the temperatures and times of chill storage should be controlled during all stages, from raw materials through retail sale and preferably to the home. The lower the temperature throughout the process, the slower the rate of growth; and (iv) attention must be given to the hygiene of the entire process to ensure that microbial contamination is minimized.

Campylobacter jejuni is a frequently detected food-borne pathogenic bacterium. Clinical cases are mostly sporadic but campylobacteriosis can have serious consequences, such as the development of Guillain–Barré syndrome as well as diarrheal diseases. We examined 265 retail raw chickens from Korean markets for the presence of C. jejuni using the US Food and Drug Administration standard cultural method and multiplex polymerase chain reaction (mPCR). The mPCR-confirmed C. jejuni isolates were subtyped by pulsed field gel electrophoresis (PFGE) and flaA-typing for investigating the genetic diversity of the microorganism in retail raw chickens. Restriction enzymes SmaI and DdeI were used for PFGE and flaA-typing, respectively. Campylobacter spp. were found in 181 samples (68.3%) and C. jejuni in 100 samples (37.74%). For C. jejuni, 73 pulsotypes and 30 flaA types were detected. Antibiotic resistance tests performed by disk diffusion assay indicated that most C. jejuni isolates were resistant to tetracycline, nalidixic acid, and ciprofloxacin, and 87 composite types were revealed by PFGE, flaA-typing, and the antibiotic resistance tests. Our results show that the genetic diversity of C. jejuni isolates is very high and the correlation between genotype and antibiotic resistance was low even though many bacteria showed multi-drug resistance.

The purpose of this study was to establish the prevalence and possible contamination routes of Campylobacter spp. in a pig slaughterhouse. Swab samples were taken from the last part of rectum, from the carcasses surface before meat inspection and from slaughter line surface from 4 different pig herds during slaughtering. Identification of Campylobacter isolates was determined by the use of phase-contrast microscopy, hippurate hydrolysis, indoxyl acetate hydrolysis tests and PCR based restriction fragment length polymorphism method (PCR-RFLP). Pulsed-field gel electrophoresis (PFGE) typing using two macro-restriction enzymes SmaI and SalI was applied to in-slaughterhouse contamination analysis of pig carcasses. The study showed that 28 (63.6%) of the 44 samples collected at slaughterhouse were contaminated by Campylobacter spp. Up to 5 different colonies were obtained from each swab sample and a total of 120 different isolates were collected. 23.4% (28 of 120) isolates were identified as C. jejuni (19 from carcasses and 9 from slaughter line surfaces) and 76.6% (92 of 120) isolates as C. coli (28 from faeces, 47 from carcasses and 17 from slaughter line surfaces). The typing results showed identity between isolates from successive flocks, different carcasses, and places in the slaughterhouse in contact with carcasses. The results suggest that cross-contamination originated in the gastro-intestinal tract of the slaughtered pigs and that cross-contamination happened during the slaughter process.