Citation
Lemma, Amare Berhanu
(2009)
Occurence of arcobacter species in farm chicken and chicken meat at reail outlets in Malaysia.
Masters thesis, Universiti Putra Malaysia.
Abstract
The genus Arcobacter comprises the former “aerotolerant campylobacters” that
are recognized recently as emerging, potential food- and water-borne pathogens.
Like their closely related campylobacters, arcobacters are major contaminants of
poultry products rendering poultry in general and chicken in particular significant
risk factors to humans. A number of protocols have so far been described to
detect Arcobacter on food although their apparent deficiencies and the likely
underestimation therein of the actual rate of contamination are well emphasized.
Furthermore, there is a general scarcity of data on the occurrence of the bacteria
in the food chain in Malaysia. The present study was, therefore, undertaken to
evaluate the performances of existing Arcobacter isolation protocols for
maximum detection of naturally contaminated chicken meat, to determine the
occurrence of Arcobacter at two levels (chicken meat at retail outlets and
chickens in the farms) and to identify the species of the isolates.Forty-eight retail chicken meat samples were subjected to three established
protocols [modified Lammerding (method I), Steele and Mc Dermott (method II),
Houf (method III)], and an ‘in-house’ method (method IV) comprising the
enrichment procedure of Houf and the plating media and techniques specified in
the modified Lammerding protocol. Method II failed to recover the organisms
from any of the samples but Arcobacter were detected by the other protocols
(methods I, III, and IV). The Arcobacter isolates were identified by a multiplex
PCR as Arcobacter butzleri from 30 (62.5%) chicken meat samples. By
comparison, the ‘in-house’ protocol (method IV) recovered the bacteria from a
greater number of samples (24 of 48) than the modified protocol of Lammerding
(12 of 48) (p= 0.019), or the protocol of Houf (17 of 48) (p= 0.046). Each of the
methods involved some degree of false negative results with the high frequency
of positive samples detected by the ‘in-house’ protocol (50%). This suggested
that the ‘in house’ method offer a more accurate estimate of the actual
occurrence of Arcobacter on food than either of the parent protocols (method I:
25%; method III: 35.42%) thereby making it a good alternative to consider
whenever available resources proscribe the simultaneous use of multiple
methods. It is recommended that further verification and/or validation of the ‘inhouse’
protocol be made prior to its adoption. To determine the frequency of
occurrence of Arcobacter and the species distribution, fresh/‘warm’ (n= 61) and
chilled (n= 62) chicken meat parts were purchased from various retail outlets in
Selangor. Forty eight of the 123 (prevalence: 39.02%; range: 0 – 88.2%) chicken meat parts selected from five sampling sites (retail outlets) were found to be
Arcobacter-positive with A. butzleri as the only species isolated. The fresh/’warm’
chicken meat portions had a higher contamination frequency (41%) than the
chilled chicken meat parts (37.1%) although the difference was not statistically
significant (2= 0.2; p= 0.655). A farm-level survey was also conducted to assess
the presence of Arcobacter species in live chicken so as to determine whether
intestinal carriage of the bacteria accounted for its high rate of occurrence on the
chicken meat portions. The bacteria were not detected in any of 210 cloacal
swabs collected from six chicken farms in Southern (Melaka and Johor ) and
Central (Selangor) regions of peninsular Malaysia probably supporting the views
that poultry are less likely hosts for Arcobacter. Environmental factors such as
water may play the role for the presence of Arcobacter on chicken meat.
This is the first large scale study on the occurrence of Arcobacter species in the
Malaysian food production chain and the first to establish the distribution of
species. Overall, the findings of the study indicated arcobacters to constitute a
major proportion of the chicken meat microbiota rendering this product a
significant risk factor for human acquisition of the organisms.
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