Identification of enterotoxigenic Staphylococcus aureus strains from meat and dairy products by multiplex PCR and reverse passive latex agglutination test in Nairobi, Kenya
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Date
2015
Authors
Mathenge, J.M.
Okemo, P.O.
Ng'ang'a, P.M.
Mbaria, J.M.
Gicheru, M. M.
Journal Title
Journal ISSN
Volume Title
Publisher
Kenyatta University School of Medicine
Abstract
Background: Foods of animal origin,
especially meat and dairy products,
are sometimes associated with food
borne diseases. In many countries,
Staphylococcus aureus is considered the
second or third most common pathogen
responsible for outbreaks of food
poisoning. In Kenya enterotoxigenic
staphylococcal food poisoning poses a
potential health hazard to the consumers
of meat and dairy products but little data
is available about the strains involved in
food poisoning.
Objective: The primary objective of this
study were to investigate the occurrence
of different strains of Staphylococcus
aureus in meat and milk products and to
determine the existence of gene coding,
the classical staphylococcal enterotoxins.
Methodology: The survey was a crosssectional
descriptive study targeting meat,
dairy products and meat processing plant.
The study was confined in randomly
selected meat and milk outlets in the
Central Business District of Nairobi
(CBDN) and its surroundings. Four
hundred and twenty food samples of
animal origin, comprising of meat and
dairy products, were randomly sampled.
Genes coding classical staphylococcal
enterotoxins were profiled using multiplex
Polymerase Chain Reaction (PCR) and
the production by Reversed Passive Latex
Agglutination (RPLA). Two hundred and
fifty one samples of raw pork and packed
pork products from a local processing
factory were similarly tested.
Results: Data from a total 671 samples
were examined and 37.4% of them were
contaminated with S. aureus in which
the contamination rate was higher in
meat products than in the milk products.
Enterotoxin production was detected in
74.5% of the isolated strains of S. aureus.
Staphylococcal enterotoxin genes (ses)
were detected in 77.3% of the total
isolates. The most frequent gene was sea
(61.8%) followed by see (33.1%), sed
(17.5%) and see (15.9%) respectively.
Staphylococcal enterotoxin B (seb) was
the least occurring gene in the S. aureus
isolates examined (13.9%). Genes
occurring in pairs included Sea/See
(21.2%), Sea/Sed (9.8%), Sed/See (2.1 %),
Sea/See (0.7%) and Seb/Sec (0.5%) among
others. A relatively low number 4 (2.1 %)
of discrepancies between the results of
multiplex PCR and RPLA were found
where by the sed genes were expressed by
PCR but the corresponding toxins were
not detected by RPLA.
Conclusions: The study clearly indicated
that meat and milk products marketed
in and around Nairobi, Kenya were
contaminated with enterotoxigenic
S. aureus posing a high risk of food
poisoning to the consumers. Equally, these
data demonstrated that multiplex PCR and
RPLA are useful methods for detection
of enterotoxigenic potential of S. aureus.
There is need for strict hygienic and
preventive measures to the manufacturer,
distributors and consumers of meat and
milk products since the contamination of
S. aureus is greater than other pathogenic
bacteria previously reported.
Description
Journal Articles scanned from a hard copy of the East and central Africa medical journal
Keywords
Staphylococcal enterotoxin, PCR, RPLA meat, Dairy products
Citation
East and Central Africa Medical Journal 2015; 2(2): 97-103