Food Protection Trends - January/February 2015 - 50

presence in meat products a matter of public health
concern (11). For instance, a report from the World Health
Organization showed an annual estimate of 1.8 million
deaths resulting from diarrheal diseases caused by microbial
pathogens (36). Recent changes in eating habits, mass
catering services, and poor hygienic practices have been
identified as contributing factors to this plight, particularly
in developing countries (17).
Sources of poultry meat contamination with pathogenic
microbes include the contents of the intestinal tract of
slaughtered birds, fecal material on feet and feathers, meat
handlers, product packing and marketing (2, 32). Globally,
the most challenging contaminants of raw and processed
meat products are members of the family Enterobacteriaceae,
particularly Salmonella, Escherichia, Proteus and Klebsiella
(2). Most genera of Enterobacteriaceae, which also include
Enterobacter, Serratia, Stenotrophomonas and Yersinia, are
overt and opportunistic pathogens, many of which have
been isolated from hospital settings, where they are strongly
associated with nosocomial infections (24, 30). The disease
burden caused by the pathogens is further increased by high
levels of antibiotic resistance, leading to complications in the
treatment of clinical cases.
In addition to causing diseases in humans, species of
Proteus, Salmonella, Yersinia and Citrobacter have been
incriminated in spoilage of refrigerated meat and poultry
products (21). In the U.S., for example, reports have shown
annual wastage of approximately 3.5 billion kg of meat
products at the retail and consumer levels, due mainly to
microbial spoilage (22).
The burden of disease and losses from product waste as a
result of microbial contamination calls for proper monitoring
of the pathogens in meat and poultry products, and for the
development of effective control strategies. A few studies
have been conducted in South Africa to assess microbial
contamination of ready-to-eat (RTE) street-vended foods (5,
26). However, there is inadequate information on microbial
contamination of raw and RTE poultry products that are
consumed with or without further processing. Therefore,
the present study was conducted to evaluate the incidence
and antibiotic resistance of coliforms in raw and RTE broiler
products obtained from the North West Province (NWP) of
South Africa.
MATERIALS AND METHODS
Sampling
A cross-sectional study was carried out in the Northwest
Province of South Africa, where 180 samples of both raw
and RTE chicken products were obtained from various retail
outlets. The outlets sampled consisted of supermarkets (n
= 120) and butcheries (n = 60). Samples obtained included
whole broiler carcasses (n = 45), raw chicken portions (n =
75) and RTE products such as polonies and viennas (n = 60).
The sampling was done during the summer months, when

50

Food Protection Trends

January/February

conditions are expected to favor growth of many bacteria.
Samples were purchased under refrigeration conditions, held
in separate sterile plastic containers at 4oC and transported
immediately to the laboratory for analysis. All samples
purchased were within the expiration date for consumption.
Bacterial culture and isolation
To evaluate the coliform contamination of the samples, 25
g of each sample was aseptically removed and homogenized
with 225 ml of buffered peptone water (BPW) in a stomacher
bag (Nasco, USA) (29). Each bag was sealed and incubated
at 37oC for 18 hours. Following incubation, contents of
each bag were homogenized, and 1 ml and 0.1 ml portions
of the liquid were transferred to 10 ml each of Luria broth
(LB) (Merck, SA). The broths were incubated at 37oC for 24
hours. A loopful of each broth sample was then streaked on
MacConkey agar (MA) (Merck, SA) and Blood agar (BA)
(Merck, SA). Plates were incubated at 37oC for 24 hours.
Colonies obtained were further purified on MA. Gram
staining and an oxidase test were performed on all obtained
isolates. Gram-negative and oxidase-negative isolates were
subjected to testing with Entero-pluritest®/API 20NE
(Davies diagnostics, South Africa), performed according to
manufacturer's instructions. The various coliform species
were identified by correlating colony morphology, Gram stain
results, oxidase reactions and biochemical characteristics.
Antimicrobial susceptibility testing
Isolates identified by biochemical characterization were
tested for antimicrobial susceptibility by the Kirby-Bauer
disc-diffusion method, as previously described (25), using
a panel of eight antibiotics. This method conforms to the
recommended standard of the Clinical and Laboratory
Standards Institute (2001). E. coli ATCC 25922 was used as
a control strain for the susceptibility testing. The antibiotics
consisted of ampicillin (10 µg), ciprofloxacin (5 µg),
amikacin (30 µg), trimethoprim-sulphamethoxasole (25 µg),
cefotaxime (30 µg), meropenem (10 µg), gentamicin (10 µg)
and erythromycin (15 µg).
RESULTS
Coliform bacterial species in raw broiler products
Coliforms were identified in 90 (75%) raw broiler
products analyzed. A total of eight genera of coliforms
belonging to the family Enterobacteriaceae were isolated
from raw products. These included four species of
Enterobacter (n = 34), three species of Klebsiella (n = 13),
two species of Citrobacter (n = 6) and one species each
of Serratia (n = 14), Hafnia (n = 9), Escherichia (n = 11),
Yersinia (n = 1), and Proteus (n = 2) (Table 1). In some
instances, multiple isolates were identified in one sample,
with two genera/species, although this finding usually
involved fewer pathogenic strains.
Food Protection Trends - January/February 2015

Table of Contents for the Digital Edition of Food Protection Trends - January/February 2015
