3.1. Prevalence of Escherichia coli and Total Coliform Counts in the Various Meat Types
The occurrence of E. coli and total coliform counts in the various meat types are presented in Table 1. E. coli were found in guinea fowl 35 (87.50%), Goat meat 29 (77.50%), Cow Meat 34 (85.00%), local chicken 31 (77.50%), and Sheep meat 35 (87.50%). There were no significant differences (> 0.05) among the various meat types. Nonetheless, guinea fowl and Sheep meat were most contaminated, followed by Cow meat, local chicken, and Goat meat. The contamination of the meat samples by E. coli indicates that lapses occurred during the slaughtering of the animals and transportation and selling of the meats [2]. This is because the muscle of a non-diseased life animal is indispensably sterile. Once the animal is slaughtered, the muscles are exposed and can be contaminated by microorganisms. E. coli are known to naturally harbor in the gastrointestinal tract of farm animals [17]. They cross-contaminate meats when the gastrointestinal tract ruptures during evisceration. It was observed during sampling that knives used for cutting meats were not sterilized intermittently. The tables also had remains of meat exudates and particles from previous use. All these posed as potential sources for cross-contamination of the meats by E. coli. A similar observation was made by [24] among meat sellers in the Accra metropolis. The knives and tables could harbor E. coli which cross-contaminated the meats. Therefore, some measures as described by Adzitey [25] must be adapted to control and prevent bacterial foodborne infections from the consumption of the various meat types.
Table 1: Prevalence of Escherichia coli and coliform counts in meat samples sold at the Tamale Metropolis.
Samples
|
No. of samples examined
|
aNo. (%) positive
|
Coliforms (log CFU/cm2)
|
Cow meat
|
40
|
34 (85.00)
|
2.81 (2.48-3.14)
|
Goat meat
|
40
|
29 (72.50)
|
3.72 (3.09-4.35)
|
Sheep meat
|
40
|
35 (87.50)
|
3.39 (3.25-4.53)
|
Local chicken
|
40
|
31 (77.50)
|
2.23 (2.16-3.30)
|
Guinea fowl
|
40
|
35 (87.50)
|
3.44 (3.35-4.24)
|
Overall
|
200
|
164 (82.00)
|
3.12 (2.16-4.35)
|
aNo.: the number of samples positive for Escherichia coli; range values for coliform counts.
Rasmussen et al. [13] examined locally produced chicken meat and imported chicken thighs into Ghana for E. coli and observed that the local chickens 36 (64.29%) and imported chickens 73 (55.30%) were contaminated by E. coli. Adzitey [9] also detected 56% (39/70) of E. coli in beef samples sold in the Tamale metropolis of Ghana. E. coli were observed in beef, pork, and fresh and grilled guinea fowls in the Bolgatanga municipality of Ghana [11, 12]. E. coli were not found in beef and chicken samples collected from three administrative regions (Gyeonggi, Gyeongsang, and Chungchong) of Korea [26]. Of 119 chicken slices of meat sampled in the city of Taif, Saudi Arabia, 31.1% showed contamination with E. coli [27]. In the Bhaktapur Metropolitan City of Nepal, E. coli were detected in 33 (33.00%) of chicken meats [28]. In the United States of America, Zhao et al. [29] reported that 83.5% of chicken breasts were contaminated with E. coli. The findings of Zhao et al. [29] were similar to this study; however, lower contamination rates were reported by [9, 13, 27, 28].
The total coliform counts were 3.44 log CFU/cm2 for guinea fowl, 3.39 log CFU/cm2 for sheep meat, 3.72 log CFU/cm2 for Goat meat, 2.81 log CFU/cm2 for Cow meat, and 2.23 log CFU/cm2 for local chicken. Thus, it was highest for guinea fowl, followed by chevon, mutton, beef, and local chicken. However, statistical differences (>0.05) were not observed among the meat types. Coliforms include Citrobacter, Enterobacter, Hafnia, Klebsiella, and Escherichia coli species, and the detection of coliforms in the meat samples is an indication of faecal contamination or processing under an unsanitary environment [17]. Kim and Yim [26] reported an average coliform count of 0.37 log cfu/g in meat samples collected from Gyeonggi, Gyeongsang, and Chungchong in Korea. The coliform counts were 0.30+- 0.78 and 1.03+-1.28for beef and chicken, respectively [26]; this study found higher coliform counts in the meat samples examined. In Ghana, Antwi-Agyei and Maalekuu [30] recorded total coliform counts of cfu/g (7.55 log cfu/g) for goat meat and cfu/g (7.33 log cfu/g) for cattle meat, which were higher than the present study. Maharjan et al. [31] reported that more than 80% of meat samples collected from Kathmandu, Nepal, had coliform bacteria.
3.2. Phenotypic Antimicrobial Susceptibility Testing of Escherichia coli
The phenotypic antimicrobial resistance of the 60 E. coli isolates is shown in Tables 2 and 3. The E. coli isolates were highly resistant to erythromycin (85.00%), tetracycline (73.33%), and ampicillin (71.67%) but susceptible to gentamicin (88.33%), ciprofloxacin (85.00%), sulphamethoxazole/trimethoprim (85.00%), chloramphenicol (83.33%), and ceftriaxone (80.00%). Intermediate resistance was observed for all the antibiotics examined, and it ranged from 3 to 10%. The E. coli of meat origin being resistant to antimicrobials can be linked to their use in animal production. Residues from these antimicrobials can also be deposited in meats which can be transferred into humans when consumed. The overall consequence is humans not responding to antimicrobial treatments due to the presence of resistant strains or residues in them. In Ghana, antibiotics are mainly used as prophylactics and treatment of sick animals, rather than as growth promoters. Ekli et al. [1] reported that antimicrobials including ciprofloxacin (32.0%), sulphamethoxazole/trimethoprim (17.1%), gentamicin (1.8%), ceftriaxone (0.9%), chloramphenicol (0.9%), and tetracycline (0.9%) were used by farmers in Wa, municipality of Ghana, as prophylactics or to treat animal diseases. They also indicated that the farmers (73.2%) did not observe withdrawal periods when they administer, or antimicrobials are administered to their animals before sales or slaughter. These prone bacteria of these animals develop resistance to antimicrobials and deposition of antimicrobial residues in their muscle tissues.
Table 2: %age antibiotic resistance of Escherichia coli isolated from meat samples in Ikorodu.
Antimicrobial
|
S
|
I
|
R
|
(%)
|
(%)
|
(%)
|
Ampicillin (Amp) 10 μg
|
≤13
|
14-16
|
≥17
|
71.67
|
10.00
|
18.33
|
Ciprofloxacin (CIP) 5 μg
|
≤15
|
16-20
|
≥21
|
8.33
|
6.67
|
85.00
|
Ceftriaxone (Cro) 30 μg
|
≤19
|
20-22
|
≥23
|
16.67
|
3.33
|
80.00
|
Chloramphenicol (C) 30 μg
|
≤12
|
13-17
|
≥18
|
10.00
|
6.67
|
83.33
|
Erythromycin (E) 15 μg
|
≤13
|
14-22
|
≥23
|
85.00
|
10.00
|
5.00
|
Gentamicin (Cn) 10 μg
|
≤12
|
13-14
|
≥15
|
6.67
|
5.00
|
88.33
|
Sulphamethoxazole/trimethoprim (Sxt) 25 μg
|
≤10
|
11-15
|
≥16
|
8.33
|
6.67
|
85.00
|
Tetracycline (Te) 30 μg
|
≤11
|
12-14
|
≥15
|
73.33
|
6.67
|
25.00
|
Overall (%)
|
|
|
|
37.71
|
6.04
|
56.25
|
Key- S: susceptible; I: intermediate; R: resistant.
Table 3: Antibiotic resistance profile and multiple antibiotic resistance index of individual Escherichia coli isolated from meat samples in Sabo Market, Ikorodu.
Serial No.
|
Escherichia coli code
|
Source
|
Antibiotic-resistant profile
|
Number of antibiotics
|
MAR index
|
1
|
CC15
|
Sheep meat
|
|
0
|
0.00
|
2
|
AM13
|
Goat meat
|
Amp
|
1
|
0.13
|
3
|
NB1
|
Cow meat
|
E
|
1
|
0.13
|
4
|
CB1
|
Goat meat
|
E
|
1
|
0.13
|
5
|
CC2
|
Sheep meat
|
E
|
1
|
0.13
|
6
|
NB15
|
Cow meat
|
E
|
1
|
0.13
|
7
|
NC10
|
Sheep meat
|
E
|
1
|
0.13
|
8
|
NLC5
|
Local chicken
|
E
|
1
|
0.13
|
9
|
Cg3
|
Guinea fowl
|
Te
|
1
|
0.13
|
10
|
NC3
|
Sheep meat
|
AmpE
|
2
|
0.25
|
11
|
CM11
|
Goat meat
|
AmpE
|
2
|
0.25
|
12
|
CM15
|
Goat meat
|
AmpE
|
2
|
0.25
|
13
|
NM3
|
Goat meat
|
AmpE
|
2
|
0.25
|
14
|
AC10
|
Sheep meat
|
TeAmp
|
2
|
0.25
|
15
|
CM4
|
Goat meat
|
TeCro
|
2
|
0.25
|
16
|
Cg5
|
Guinea fowl
|
TeE
|
2
|
0.25
|
17
|
Cg15
|
Guinea fowl
|
TeE
|
2
|
0.25
|
18
|
NLC15
|
Local chicken
|
TeE
|
2
|
0.25
|
19
|
Tg14
|
Guinea fowl
|
TeE
|
2
|
0.25
|
20
|
AB7
|
Cow meat
|
AmpCCn
|
3
|
0.38
|
21
|
AM1
|
Goat meat
|
AmpECn
|
3
|
0.38
|
22
|
CM15
|
Goat meat
|
AmpE
|
2
|
0.25
|
23
|
NB8
|
Cow meat
|
AmpECro
|
3
|
0.38
|
24
|
CM1
|
Goat meat
|
TeAmpCn
|
3
|
0.38
|
25
|
NC1
|
Sheep meat
|
TeAmpCro
|
3
|
0.38
|
26
|
AC15
|
Sheep meat
|
TeAmpE
|
3
|
0.38
|
27
|
AM14
|
Goat meat
|
TeAmpE
|
3
|
0.38
|
28
|
CB4
|
Goat meat
|
TeAmpE
|
3
|
0.38
|
29
|
CB9
|
Goat meat
|
TeAmpE
|
3
|
0.38
|
30
|
CB13
|
Goat meat
|
TeAmpE
|
3
|
0.38
|
30
|
CC6
|
Sheep meat
|
TeAmpE
|
3
|
0.38
|
31
|
CC10
|
Sheep meat
|
TeAmpE
|
3
|
0.38
|
32
|
NB12
|
Cow meat
|
TeAmpE
|
3
|
0.38
|
33
|
NM7
|
Goat meat
|
TeAmpE
|
3
|
0.38
|
34
|
Cg9
|
Guinea fowl
|
TeAmpE
|
3
|
0.38
|
35
|
Sg1
|
Guinea fowl
|
TeAmpE
|
3
|
0.38
|
36
|
Sg15
|
Guinea fowl
|
TeAmpE
|
3
|
0.38
|
37
|
Tg9
|
Guinea fowl
|
TeAmpE
|
3
|
0.38
|
38
|
TLC1
|
Local chicken
|
TeAmpE
|
3
|
0.38
|
39
|
TLC4
|
Local chicken
|
TeAmpE
|
3
|
0.38
|
40
|
TLC10
|
Local chicken
|
TeAmpE
|
3
|
0.38
|
41
|
NLC3
|
Local chicken
|
TeSxtE
|
3
|
0.38
|
42
|
SLC11
|
Local chicken
|
TeSxtE
|
3
|
0.38
|
43
|
SLC15
|
Local chicken
|
TeSxtE
|
3
|
0.38
|
44
|
TLC13
|
Local chicken
|
TeSxtE
|
3
|
0.38
|
45
|
AB1
|
Cow meat
|
AmpCipCroC
|
4
|
0.50
|
46
|
AM9
|
Goat meat
|
TeAmpECro
|
4
|
0.50
|
47
|
AB13
|
Cow meat
|
TeAmpSxtE
|
4
|
0.50
|
48
|
NC15
|
Sheep meat
|
TeAmpSxtE
|
4
|
0.50
|
50
|
Sg6
|
Guinea fowl
|
TeAmpSxtE
|
4
|
0.50
|
51
|
Sg9
|
Guinea fowl
|
TeAmpSxtE
|
4
|
0.50
|
52
|
SLC2
|
Local chicken
|
TeAmpSxtE
|
4
|
0.50
|
53
|
SLC6
|
Local chicken
|
TeAmpSxtE
|
4
|
0.50
|
54
|
NM8
|
Goat meat
|
TeAmpCipSxtE
|
5
|
0.63
|
55
|
Tg5
|
Guinea fowl
|
TeAmpSxtEC
|
5
|
0.63
|
56
|
AC7
|
Goat meat
|
TeAmpSxtECro
|
5
|
0.63
|
57
|
AB15
|
Cow meat
|
TeAmpSxtECro
|
5
|
0.63
|
58
|
Tg1
|
Guinea fowl
|
TeAmpSxtECro
|
5
|
0.63
|
59
|
NLC9
|
Local chicken
|
TeAmpCipSxtEC
|
6
|
0.75
|
60
|
AC1
|
Sheep meat
|
TeAmpCipSxtECroC
|
7
|
0.88
|
Key: Amp: ampicillin; Cip: ciprofloxacin; Cro: ceftriaxone; C: chloramphenicol; E: erythromycin; Cn: gentamicin; Sxt: sulphamethoxazole/trimethoprim; Te: tetracycline.
Adzitey [10] observed that E. coli isolated from cow meat in Ghana were resistant to tetracycline (44.44%), erythromycin (68.89%), and chloramphenicol (44.44%), but susceptible to ciprofloxacin (95.56%), sulphamethoxazole/trimethoprim (82.22%), and gentamicin (75.56%). Resistance to tetracycline and erythromycin but not chloramphenicol was higher in the present study compared with Adzitey [10]. Similarly, high susceptibility to ciprofloxacin and gentamicin was found in both studies. Also, Rasmussen et al. [13] reported that E. coli from locally produced chicken meats were resistant to tetracycline (88.9%) and ampicillin (69.4%), while those from imported chicken meats were resistant to tetracycline (57.5%) and ampicillin (61.6%). Resistance to ampicillin in locally produced chicken meat was similar to the current study but not the rest. Saud et al. [28] found that E. coli isolated from chicken meats in Bhaktapur Metropolitan City, Nepal, were resistant to gentamicin (24.2%) and tetracycline (60.6%), which contradicts this study. E. coli from chicken meats in Indonesia were resistant to tetracycline (79.24%) and chloramphenicol (9.43%) [32], which were similar to this study. Altalhi et al. [27] observed that E. coli isolated from retail raw chicken meat in Taif, Saudi Arabia, were resistant to ampicillin (78.4%), chloramphenicol (32.4%), and gentamicin (24.3%). Resistance to ampicillin was similar to this study but lower for chloramphenicol and gentamicin. Martínez-Vázquez et al. [33] reported that E. coli from retail meats in Tamaulipas, Mexico, were resistant to ampicillin (92%) and tetracycline (75%), which were comparable to this study.
The multiple antibiotic (MAR) index ranged from 0.13 (resistant to one antibiotic) to 1.0 (resistant to eight antibiotics) (Table 3). Bacteria have originated from a high-risk source of contamination where several antibiotics or growth promoters are used while showing bacteria from the source with less antibiotic use [34, 35]. A completely resistant isolate has a MAR index of 1.0. The E. coli isolates were resistant to one (13.33%), two (16.67%), three (41.67%), four (13.33%), and five (8.33%) antimicrobials. Resistance to zero, six, seven, and eight antimicrobials was 1.67% each. The E. coli isolates also exhibited twenty-three (23) different resistance patterns. The resistance pattern TeAmpE (tetracycline-ampicillin-erythromycin) was the most common and was exhibited by sixteen isolates. Most of the E. coli isolates exhibited a MAR index of ≥0.25 reflecting a greater resistance to the group of antimicrobial agents studied. This means that there is greater antimicrobial use in production on the farms the animals were reared, which needs the attention of all relevant stakeholders in Ghana. Furthermore, E. coli isolates of meat origin with a MAR index of 0.4 and above are associated with human faecal contamination, while a MAR index of less than 0.4 is associated with nonhuman faecal contamination [36]. Based on this assumption, 26.7% of the samples were human faecal contamination and the rest were not. It has been reported that meat sellers at Sabo markets do not adhere to strict hygiene in the sale of meat, and this could contribute to faecal contamination (Adzitey et al. [37]). Similarly, Adzitey [10] showed that E. coli isolated from beef in Techiman exhibited twenty-five (25) resistance patterns, and the MAR index ranged from 0.11 to 0.78. Adzitey [10] also found that majority of E. coli isolates were resistant to three antimicrobials (14 isolates), followed by four antimicrobials (13 isolates). In addition, three and one isolates were resistant to 5 and 7 antimicrobials, respectively.
Multidrug resistance (MDR), that is, resistance to 3 or more different classes of antimicrobials, was observed in 41 (68.33%) of the isolates. Multidrug-resistant E. coli can be transferred from one carcass to the other and finally consumed by humans. Multidrug resistance is a cause for concern because it limits therapeutic options available for animal and human treatment. E. coli isolates of meat origin exhibiting multidrug resistance with susceptible ones serve as sources of resistant genes and increase the chances for the transfer of resistance genes to those that are sensitive. In Nigeria, Kehinde et al. [15] reported that 4.8% of E. coli from meat sources were multidrug-resistant to cefuroxime-chloramphenicol-ampicillin. Altalhi et al. [27] found that E. coli of raw chicken meat were resistant to one or more antimicrobials. They also found that 86.5% were resistant to at least one antimicrobial and 40.5% of the isolates were resistant to at least three antimicrobials. Saud et al. [28] observed 52.5% multidrug resistance in E. coli isolates of meat origin (chicken and buffalo meat). In addition, they found overall multidrug resistance of 69.81%, and resistance to zero, one, two, three, four, five, and six antibiotics was 13.21%, 16.98%, 33.96%, 15.09%, 20.75%, 0.00%, and 0.00%, respectively [30]. In Tamaulipas, Mexico, Martínez-Vázquez et al. [33] detected that 92.4% of E. coli obtained from retail meats exhibited multi-resistance.