VETERINARSKI ARHIV 69 (4), 191-197, 1999

ISSN 1331-8055 Published in Croatia

Isolation of bacteria during processing of chicken carcasses for the market in Lusaka, Zambia

Bernard Mudenda Hang'ombe¹*, Nath Ravindra Sharma¹, Eystein Skjerve², and Lawrence Musonda Tuchili¹

¹School of Veterinary Medicine, University of Zambia, Lusaka, Zambia

²Department of Pharmacology, Microbiology and Food Hygiene,
Norwegian College of Veterinary Medicine, Oslo, Norway

* Contact address:
Dr. Bernard Mudenda Hang'ombe,
Department of Paraclinical Studies, School of Veterinary Medicine, University of Zambia, Lubumbashi Road, Handsworth Court B4, Lusaka, Zambia,
Phone: 260 1 291 512; Fax: 260 1 291 512; E-mail: Bhangombe@vet.unza.zm

Hang'ombe, B. M., N. R. Sharma, E. Skjerve, L. M. Tuchili: Isolation of bacteria during processing of chicken carcasses for the market in Lusaka, Zambia. Vet. arhiv 69, 191-197, 1999.

ABSTRACT

A study was carried out in a poultry processing plant in Lusaka, Zambia, to identify and describe bacteria found in chicken carcasses leaving the processing plant for retail outlets. The thirteen different bacteria found in the chicken carcasses included: Escherichia coli (41.7%), Staphylococcus spp. (2.49%), Pseudomonas spp. (6.71%), Klebsiella spp. (1.91%), Salmonella spp. (20.53), Citrobacter spp. (6.71%), Acinetobacter spp. (0.58%), Proteus spp. (9.02%), Flavobacterium spp. (1.15%), Streptococci spp. (1.72%), Alcaligenes spp. (0.77%), Micrococcus spp. (3.84%) and Bacillus spp. (2.88%). These results showed that the chicken carcasses entering the Zambian market are a potential source of bacteria pathogens to consumers. It is therefore suggested that much more attention should be paid to the processing plant in order to control the bacterial contamination of poultry meat.

Key words: bacteria, chicken carcasses, poultry meat, poultry processing plant, Lusaka, Zambia

Introduction

Several different species of micro-organisms have been reported in poultry meat. Some of these micro-organisms are pathogenic, while others are non-pathogenic. Of the microbes known as human pathogens, poultry are often known to be sources of Salmonella spp. and Campylobacter jejuni infections in man (SIMMONS and GIBBS, 1979; BRYAN, 1980, 1981; GRANT et al., 1980; SHANKER et al., 1982). Other pathogens may be found in poultry carcasses, although no causal relations to human infections are documented. This group includes Aeromonas hydrophila (BARNHART et al., 1989; BARNHART and PANCARBO, 1992) and Listeria monocytogenes (BAILEY et al., 1989).

Organisms often found in poultry carcasses also include a number of bacteria causing food poisoning due to extensive growth and eventual production of potent toxins in foods. These organisms are Staphylococcus aureus, Clostridium perfringens and Clostridium botulinum, often detected in poultry carcasses, but also found in a wide range of other foods (MULDER and DORRESTEIJN, 1977; HARRIGAN, 1980; MULLER-HOHE, 1989). Other bacteria are involved in the spoilage of meat; these include Micrococcus spp., Staphylococcus spp., Streptococcus spp., Lactobacillus spp., Bacillus spp., Clostridium spp., Corynebacterium spp., Pseudomonas spp., Flavobacterium spp., Acinetobacter spp., Alcaligenes spp., Escherichia coli and Klebsiella spp. (GRACEY and COLLINS, 1994). Some of these originate from the poultry itself, but may also stem from the abattoir environment.

No published literature is available on the isolation of bacteria from poultry meat in Zambia, and the present study was undertaken to describe the bacterial contamination of poultry meat packaged at a Zambian poultry abattoir.

Materials and methods

The study was conducted for a period of four months, from mid-March to June 1997, at a central processing plant in Lusaka, Zambia. The plant processes poultry from different farms around Lusaka. At this processing plant, the broiler carcasses are routinely dipped in chlorinated water prior to packing, using calcium hypochlorite (Olin Corporation, South Africa). Initially, 200 grams of calcium hypochlorite are added to 500 litres of water, and a further 50 grams is added after about every three hours. The period that carcasses remain in chlorinated water is not usually monitored.

The carcasses were swabbed with sterile cotton swabs on emerging from the chiller in the packaging chain, from where they are destined for final packaging to enter the market. A carcass was selected after every 10 minutes in the packaging chain, and then sampled. A total of 382 carcasses were sampled throughout the 13-weeks sampling period. The inside of the visceral cavity and cloacal area surfaces were swabbed. Two swabs were used for each sampling; one swab was placed in 10 ml of selenite broth (Biotec, Suffolk, UK) and the other in peptone broth (Difco, Michigan, USA) directly after swabbing. The broths were returned to the laboratory and incubated at 37.5 °C for 24 hours. After incubation, one loop of selenite broth was plated on xylose lysine deoxycholate (Oxoid, Hampshire, UK) and one loop of peptone broth on Trypticase soy agar (TSA, Becton Dickinson, Cockeysville, USA). The plates were incubated aerobically at 37.5 °C for 24 hours.

The cultures from the plates were purified by subculture into single identical colonies. This was done by single selection of different colonies on a plate. Each colony was re-cultured on TSA, where similar growth in terms of morphology was used for further identification. Identification of isolates was done using routine bacteriological methods as detailed by COWAN and STEEL (1977) and HOLT et al. (1994). A selected number of Escherichia coli isolates was serotyped using Escherichia coli anti-sera supplied by Denka Seiken Co., Tokyo, Japan, while the Salmonella spp isolates were serotyped at Ondersterpoort Veterinary Institute, South Africa. The Staphylococcus spp isolates were tested for coagulase test using rabbit plasma.

Statistical analysis

The percentage of isolation was calculated for each week. Based on these figures, the partial correlation between the different bacteria were calculated using the software package JMP for Windows (Version 3.2, 1997, SAS Institute, Inc.)

Results

All sampled carcasses yielded some bacteria growth on TSA. Some had more than two bacteria species isolated, despite the technique used. A total of 521 isolates, comprising 13 bacteria species, were identified (Table 1). Escherichia coli had the highest frequency of isolation, (41.65%), followed by Salmonella spp. (20.53%).

Table 1. Bacteria isolates from chicken carcasses in Lusaka, Zambia

Pair-wise correlation between the different bacteria was done and is as shown in Table 2.

Table 2. Partial correlation between isolation percentages of
different bacteria in poultry carcasses

Escherichia coli and Salmonella spp. isolations were predominant at each isolation during the 13 weeks of study. The mean percentage of isolations of Escherichia coli and Salmonella spp. were 56.5% and 27.5% respectively.

The 30 serotyped Escherichia coli isolates against specific anti-sera were: O111:K58 (2), O26:K60 (2), O26:K- (4) and 22 were of the rough type, i.e. untypable. Eight of 13 Staphylococcus spp. isolates tested positive for coagulase. Serotypes of Salmonella isolates are presented in Table 3.

Table 3. Serovars of 107 Salmonella isolates from chicken carcasses

Discussion

Predominant bacteria isolated in this study were: Salmonella, Escherichia coli, Klebsiella, Staphylococci, Streptococci, Alcaligenes, Pseudomonas, Citrobacter and Proteus, which can be opportunistic pathogens of humans. Of definite significance is Salmonella spp., which has been isolated. Other bacteria from this study have been isolated from human clinical specimens (CARTER and COLE, 1990; HOLT et al., 1994) and outbreaks of food poisoning (GRACEY and COLLINS, 1994).

Some of these bacteria can contribute to chicken meat spoilage. From this study it was established that bacteria that can cause chicken carcass spoilage are: Pseudomonas, Alcaligenes, Micrococcus, Staphylococcus, Streptococcus, Bacillus, Flavobacterium and Escherichia coli as indicated by MOUNTNEY (1983) and GRACEY and COLLINS (1994). Variations exist in the percentages of isolations for different bacteria due to the fact that the birds came from different farms with differences in their management. As can be seen in Table 2, there were some high positive as well as negative correlations found between some of the bacteria. However, it may be difficult to provide a direct interpretation of these results, as competition among different bacteria in the broth may have confounded the results.

Salmonella contamination in poultry has been recognised by the formulation of legislation, laws and regulations throughout the world (ZIVKOVIC et al., 1997), as it is very common in many areas. In this study 27.5% of the chicken carcasses sampled were found positive for Salmonella. Other workers in different parts of the world gave varying isolation rates of Salmonella bacteria. Salmonella serovars reported in a number of similar studies include: S. anatum, S. mbandaka, S. seftenberg, S. hadar, S. typhimurium, S. enteritidis, S. agona, S. saintpaul and S. newport (DEZEURE-WALLAYS et al., 1980; BERNADO and MACHADO, 1989). In this study, four Salmonella serovars have been documented. In this study, S. mbandaka had the highest percent of isolation and was documented for the first time in Zambia. Salmonella enteritidis is well documented as a human pathogen. Isolation of Salmonella enteritidis from market-ready chicken carcasses is a matter for concern. Salmonella enteritidis and Salmonella mbandaka have not yet been documented in the Zambian human population, but work is underway to assess the importance of different varieties of Salmonella in humans in Zambia.

The qualitative method used in this study did not permit an independent assessment of the number of the different bacteria. The swabs may collect only some of the bacteria present, and competition between different bacteria in the broth may confound the results.

There is a need to revisit the processing procedures, with identification and monitoring of the most critical points in the production process in order to reduce the contamination rate. Further work should concentrate on quantifying the numbers of Enterobacteriaceae, as well as monitoring the prevalence of isolation of major pathogens such as Salmonella spp. and Campylobacter spp.

Acknowledgments
We are grateful to Norwegian University Fund (NUFU) for their financial support of the research project, and to Dr. Martie van der Walt, microbiologist, Onderstepoort Veterinary Institute South Africa, for serotyping of the Salmonella isolates. Thanks are also due to Mr. Don Mule, Microbiology Laboratory, for his technical assistance.

References

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Received: 15 June 1999
Accepted: 18 October 1999

Hang'ombe, B. M., N. R. Sharma, E. Skjerve, L. M. Tuchili: Izolacija bakterija tijekom klaonicke obrade pilica za trziste u Lusaki u Zambiji. Vet. arhiv 69, 191-197, 1999.

SAZETAK

Istrazivanje je izvrseno u klaonici peradi u Lusaki u Zambiji te su utvrdene i opisane bakterije nadene u zaklanoj peradi koja se iz klaonice dostavlja u prodavaonice na malo. U truplima pilica ustanovljene su bakterije iz 13 razlicitih rodova: Escherichia coli (41,7%), Staphylococcus spp. (2,49%), Pseudomonas spp. (6,71%), Klebsiella spp. (1,91%), Salmonella spp. (20,53), Citrobacter spp. (6,71%), Acinetobacter spp. (0,58%), Proteus spp. (9,02%), Flavobacterium spp. (1,15%), Streptococci spp. (1,72%), Alcaligenes spp. (0,77%), Micrococcus spp. (3,84%) i Bacillus spp. (2,88%). Dobiveni rezultati pokazuju da zaklana perad koja dolazi na trziste u Zambiji predstavlja mogucu opasnost i izvor patogenih bakterija za potrosace. Stoga se preporuca mnogo veca higijenska kontrola u klaonicama peradi kako bi se sprijecilo bakterijsko zagadenje piletine.

Kljucne rijeci: bakterije, zaklani pilici, piletina, klaonica peradi, Lusaka, Zambija