Proportional distribution of Staphylococcus isolates in farm
Of an overall examined samples from six different farms (222), 64 (28.8%), [95%CL:28.12–29.54] were positive for Staphylococcus species, from which 4/22 (18.2%), 21/59 (35.6%), 10/28 (35.7%), 14/62 (22.6%), 11/23 (47.8%) and 4/28 (14.3%) from AM, BD, EU, HM, SA, and TE farm, were positive for Staphylococcus species, respectively. There was statistically differed significantly in isolation of Staphylococcus between different farm (p = 0.046)
Proportional distribution of Staphylococcus isolates in housing system and sample source
From two poultry housing system, cage type and deep litter system, 4/28 (15.69%), and 58/194 (31.71%), were positive for Staphylococcus, respectively. For samples examined from layers (Bo vans Brown) and broilers (White Leg Horne), 10/57 (17.54%) and 45/134 (33.58%) were positive for Staphylococcus, respectively, but the highest percentage 7/17 (41.18%) was isolated from litter and the lowest percentage 2/4 (14.29%) was isolated from farm workers, however there was no statistically significant difference in isolation of Staphylococcus between different housing system (P-value = 0.103) and sample source (P-value = 0.052) (Table 1).
Proportional distribution of Staphylococcus isolates in sample type
Of the total 64/222 (28.8%) Staphylococcus isolates, 33/101 (32.7%), 22/90 (24.44%), 7/17 (41.2%) and 2/7 (28.6%), from cloacal swab, tracheal swab, pooled litter swab and nasal swab of farm attendants, were positive for Staphylococcus, respectively, but no isolate was found from pooled hand and boot swab of farm attendants 0/7 (0%). There was no statistically significant difference in Staphylococcus isolation between different sample type (P-value = 0.225) (Table 1).
Proportional distribution of Staphylococcus species in farm
Table 1
Distribution of Staphylococcus isolates in different farms, housing system, sample source and sample types
| Positive | Total | Prevalence (%) | 95%CI | x2 | P |
Farm name | M | 4 | 22 | 18.18 | 16.40, 19.96 | 11.92 | 0.046 |
D | 21 | 59 | 35.59 | 34.07, 37.12 | | |
U | 10 | 28 | 35.71 | 33.50, 37.93 | | |
M | 14 | 62 | 22.58 | 21.40, 23.76 | | |
A | 11 | 23 | 47.83 | 45.00, 50.65 | | |
E | 4 | 28 | 14.29 | 12.89, 15.69 | | |
Housing system | C | 4 | 28 | 14.29 | 12.89, 15.69 | 3.30 | 0.07 |
L | 60 | 194 | 30.93 | 30.15, 31.71 | | |
Sample source | B | 45 | 134 | 33.58 | 32.60, 34.56 | 7.72 | 0.052 |
L* | 7 | 17 | 41.18 | 38.13, 4.23 | | |
Ly | 10 | 57 | 17.54 | 16.46, 18.63 | | |
P | 2 | 14 | 14.29 | 12.31, 16.27 | | |
Sample type | C | 33 | 101 | 32.67 | 31.56, 33.79 | 5.67 | 0.225 |
HB | 0 | 7 | 0.00 | - | | |
L* | 7 | 17 | 41.18 | 38.13, 44.23 | | |
N | 2 | 7 | 28.57 | 24.61, 32.53 | | |
T | 22 | 90 | 24.44 | 23.42, 25.47 | | |
Total | 64 | 222 | 28.83 | 28.12, 29.54 | | |
Key = AM = Amelewerk farm enterprise; BD = Bayissa Damessa farm; EU = Europe farm enterprise; HM = Haile Michael farm; SA = Senait and Abdella and their friends TE = Tesfaye farm enterprise; C = Cage type housing system; L = Litter type housing system; P = Personnel, Ly = layer, B = Broiler, Cl = Cloacal swab; L*= Litter swab, T = Tracheal swab; N = Nasal swab; HB = Hand
Proportional distribution of Staphylococcus species in housing system
After isolation and identification of Staphylococcus species, 40 (18.01%), 11 (4.95%), 3 (1.4%), 10 (4.5%) were S. aureus, S. hycus, S. intermedius and Coagulase negative staphylococci (CNS) from the total sample examined, respectively and none of the farm is free of the bacteria. Of the isolates, S. aureus 40/64 (62.5%) was the most dominant followed by S. hycus 11/64 (17.2%) and CNS 10/64 (15.6%); and lastly S. intermedius 3/64 (4.7%). From the species isolated and identified only S. aureus was isolated from all farms with highest prevalence in farm BD, 19/59 (32.2%), and lowest in farm SA, 1/23 (3.4%). Other staphylococcal species, S. hycus was isolated only from three farms, BD 2/59 (3.4%), EU 3/28 (10.7%) and SA 6/23 (26.1%); and S. intermedius and CNS were also isolated from three similar farms, EU, HM and SA, with 1/28 (3.6%), 1/62 (1.6%), 1/23 (4.3%) S. intermedius and 4/28 (14.3%), 3/62 (4.8%) and 3/23 (13%) CNS, respectively. There was statistically differed significantly in isolation and identification of Staphylococcus species between different farm except for S. intermidius (P = 0.53) (Table 2).
Proportional distribution of Staphylococcus species in sample source and sample type
From two types of housing system (cage and deep litter) 34/194 (18.6%) and 4/28 (14.3%) from deep litter and cage type housing system, were positive of S. aureus, respectively, but S. hycus,11/194 (5.7%),, S. intermedius, 3/194 (1.6%) and CNS, 10/194 (5.2%) were only isolated from deep litter housing system, and there was no statistically significant difference in Staphylococcus species isolated and identified between housing system, since the P- value in all species is (P-value > 0.05) (Table 2).
Among the Staphylococcus species S. aureus was isolated from all sample sources, broiler (17.9%), layer (17.5%), litter (23.5%) and personnel (14.3%). Both S. hycus and CNS with the same result (6.7%) were isolated from broilers; S. intermedius was only isolated from broiler (2.2%). There was no statistically significant difference in Staphylococcus species isolated and identified between different sample sources (P-value ≥ 0.05 in all species) (Table 2). All the staphylococcal species were isolated from different sample types, but none of them identified from pooled hand and boot swab of farm attendants. S. aureus was highest (28.6%) in nasal swab and lowest (12.9%) in cloacal swab. S. aureus 4(23.5%). S. hycus 2(21.8%) and CNS 1(5.9%) were isolated from litter, but S. intermiedius not. S. intermidius was only isolated from cloacal swab, 3/101 (3%). There was no statistically significant difference in Staphylococcus species isolated from different sample types except CNS (p = 0.05) (Table 2).
Table 2
The proportional distribution of Staphylococcus species isolated from different farms, housing systems, sample sources and different sample types
| Staphylococcus species, n (%) |
CNS | SA | SH | SI |
Farm name | AM (n = 22) | | 0 (0.0) | 4 (18.2) | 0 (0.0) | 0 (0.0) |
BD (n = 59) | | 0 (0.0) | 19 (32.2) | 2 (3.4) | 0 (0.00 |
EU (n = 28) | | 4 (14.3) | 2 (7.1) | 3 (10.7) | 1 (3.6) |
HM (n = 62) | | 3 (4.8) | 10 (16.1) | 0 (0.0) | 1 (1.6) |
SA (n = 23) | | 3 (13) | 1 (3.4) | 6 (26.1) | 1 (4.3) |
TE (n = 28) | | 0 (0.0) | 4 (14.3) | 0 (0.0) | 0 (0.0) |
x2(p-v) | | | 15.28(0.01) | 13.60(0.02) | 29.93(0.00) | 4.12(0.53) |
Housing system | C (n = 28) | | 0 (0.0) | 4 (14.3) | 0 (0.0) | 0 (0.00 |
L (n = 194) | | 10 (5.2) | 36 (18.6) | 11 (5.7) | 3 (1.6) |
x2(p-v) | | | 2.30(0.32) | 0.32(0.88) | 2.55(0.29) | 0.67(0.72) |
Sample source | B (n = 134) | | 9 (6.7) | 24 (17.9) | 9 (6.7) | 3 (2.2) |
L* (n = 17) | | 1 (5.9) | 4 (23.5) | 2 (11.8) | 0 (0.0) |
Ly (n = 57) | | 0 (0.0) | 10 (17.5) | 0 (0.00 | 0 (0.0) |
P (n = 14) | | 0 (0.0) | 2 (14.3) | 0 (0.0) | 0 (0.0) |
x2(p-v) | | | 4.95(0.18) | 0.50(0.92) | 6.26(0.10) | 2.00(0.57) |
Sample type | C (n = 101) | | 9 (8.9) | 13 (12.9) | 8 (7.9) | 3 (3) |
HB (n = 7) | | 0 (0.0) | 0 (0.0) | 0 (0.0) | 0 (0.0) |
L* (n = 17) | | 1 (5.9) | 4 (23.5) | 2 (11.8) | 0 (0.0) |
N (n = 7) | | 0 (0.0) | 2 (28.6) | 0 (0.0) | 0 (0.0) |
T (n = 90) | | 0 (0.0) | 21 (23.3) | 1 (1.1) | 0 (0.0) |
x2(p-v) | | | 9.54(0.05) | 5.95(0.20) | 7.11(0.13) | 3.64(0.46) |
Total n = 64 | | 10(15.6) | 40 (62.5) | 11(17.2) | 3 (4.7) |
Key = CNS = Coagulase negative Staphylococcus; SA = S. aureus; SH = S. hycus; SI = S. intermedius; and see the previous table for others
Frequency distribution of antimicrobial susceptibility pattern of Staphylococcal isolates
All isolates (64) of Staphylococcus were tested for susceptibility test to 10 antimicrobial discs. The comparative efficacies of antimicrobial used indicate CIP and SXT were the most effective antibiotics with susceptibility percentage of 95.3%and 85.9% respectively. Conversely P and TE have shown the poorest efficacy (susceptibility) or high resistance against staphylococcal isolates with 96.9% and 78.1%, respectively (Table 3).
Table 3
Antimicrobial susceptibility profile of staphylococcal isolates (n = 64)
S/n | Antimicrobials | Number of tested | Susceptible [N (%)] | Intermediate [n (%)] | Resistance [N (%)] |
1 | P | 64 | 2 (3.1) | 0 (0.0) | 62 (96.9) |
2 | VA | 64 | 26 (40.6) | 0 (0.0) | 38 (59.4) |
3 | CIP | 64 | 61 (95.3) | 0 (0.0) | 3 (4.7) |
4 | SXT | 64 | 55 (85.90 | 0 (0.0) | 9 (14.1) |
5 | AML | 64 | 22 (34.4) | 0 (0.0) | 42 (65.6) |
6 | F | 64 | 19 (29.70 | 27 (42.2) | 18 (28.1) |
7 | E | 64 | 6 (9.4) | 16 (25.0) | 42 (65.6) |
8 | TE | 64 | 7 (10.9) | 7 (10.9) | 50 (78.1) |
9 | S | 64 | 24 937.5) | 16 (25.0) | 24 (37.5) |
10 | NA | 64 | 48 (75.0) | 5 (7.80) | 11 (17.2) |
Total | 10 | 640 | 270 (42.2) | 71 (11.1) | 299 (46.7) |
Key for Abbreviations: P = Penicillin, AML = Amoxicillin, F = Cefoxitin, CIP = Ciprofloxacin, NA = Naldixic acid, S = Streptomycin, SXT = Sulfamethoxazole trimethoprim, VA = Vancomycin, TE = tetracycline, E = Erythromycin |
Frequency distribution of antimicrobial susceptibility pattern of Staphylococcus species
Staphylococcal species have variable susceptibility pattern toward antimicrobials (Table 3). All positive samples of Staphylococcus species, S. aureus (40), S. hycus (11), S. intermedius (3) and CNS (10) were tested for susceptibility. Of the isolates 38/40 (95%) S. aureus, 10/11 (90.9) S. hycus, 10/10 (100%) CNS and 3/3 (100%) S. intermedius were resistance to three or more antimicrobials, while 1/40 (2.5%) S. aureus and 1/11 (9.1%) S. hycus showed mono resistance and only 1/40 (2.5%) S. aureus was susceptible to all antimicrobials tested. S. aureus is highly resistance (95.0%) to P and (72.5%) to both VA and TE; and highly susceptible (97.5%), and (87.5%) to CIP and SXT, respectively. S. hycus showed greater resistance (100%) to P and highly resistance (81.8%) to TE; and greater susceptible (100%) to SXT and highly susceptible (90.9%) to CIP and slightly susceptible (63.6%) to both VA and NA. Similarly S. intermedius showed greater resistance (100%) to P, AML, TE and S, but greater susceptibility (100%) was seen in VA. Moreover, CNS has showed greater resistance (100%) to P and greater susceptibility (100%) to CIP (Table 4).
Table 4
Antimicrobial susceptibility patterns of Staphylococcus species
Antimicrobials tested | Staphylococcus species [n (%)] | | |
CNS | SA | SH | SI | x2 | P |
P | R(n = 62) | 10 (100) | 38 (95.0) | 11 (100) | 3 (100) | 1.239 | 0.744 |
S (n = 2) | 0 (0.0) | 2 (5.0) | 0 (0.0) | 0 (0.0) | | |
VA | R(n = 38) | 5 (50.0) | 29 (72.5) | 4 (36.4) | 0 (0.0) | 10.02 | 0.018 |
S(n = 26) | 5 (50.0) | 11 (27.5) | 7(63.6) | 3 (100) | | |
CIP | R (n = 3) | 0 (0.0) | 1 (2.5) | 1 (9.1) | 1 (33.3) | 6.908 | 0.075 |
S(n = 62) | 10 (100) | 39 (97.5) | 10(90.9) | 2 (66.7) | | |
SXT | R(n = 9) | 2 (20.0) | 5 (12.5) | 0 (0.0) | 2 (66.7) | 9.042 | 0.029 |
S (n = 55) | 8 (80.0) | 35 (87.5) | 11 (100) | 1 (33.3) | | |
AML | R(n = 42) | 8 (80.0) | 26 (65.0) | 5 (45.5) | 3 (100) | 4.478 | 0.214 |
S(n = 22) | 2 (20.0) | 14 (35.0) | 6 (54.5) | 0 (0.0) | | |
F | I (n = 27) R(n = 18) | 1 (10.0) 7 (70.0) | 21 (52.5) 6 (15.0) | 5 (45.5) 4 (36.4) | 0 (0.0) 1 (33.3) | 16.032 | 0.014 |
S (n = 19) | 2 (20.0) | 13 (32.5) | 2 (18.2) | 2 (66.7) | | |
E | I (n = 16) R(n = 42) | 1 (10.0) 9 (90.0) | 0 (0.0) 25 (62.5) | 0 (0.0) 7 (63.6) | 1 (33.3) 1 (33.3) | 20.119 | 0.003 |
S(n = 6) | 0 (0.0) | 1 (2.5) | 4 (36.4) | 1 (33.3) | | |
TE | I (n = 7) R(n = 50) | 0 (0.0) 9 (90.0) | 7 (17.5) 29 (72.5) | 0 (0.0) 9 (81.8) | 0 (0.0) 3 (100) | 5.642 | 0.465 |
S(n = 7) | 1 (10.0) | 4 (10.0) | 2 (18.2) | 0 (0.0) | | |
S | I (n = 16) R(n = 24) | 2 (20.0) 4 (40.0) | 11 (27.5) 15 (37.5) | 3 (27.3) 2 (18.2) | 0 (0.0) 3 (100) | 7.27 | 0.297 |
S (n = 24) | 4 (40.0) | 14 (35.0) | 6 (54.5) | 0 (0.0) | | |
NA | I (n = 5) R(n = 11) | 0 (0.0) 3 (30.0) | 4 (10.0) 4 (10.0) | 1 (9.1) 3 (27.3) | 0 (0.0) 1 (33.3) | 4.931 | 0.553 |
S(n = 48) | 7 (70.0) | 32 (80.0) | 7 (63.6) | 2 (66.7) | | |
Total | 10 (15.6) | 40 (62.5) | 11(17.2) | 3 (4.7) | | |
I = intermediate, R = resistant, S = susceptible |
Frequency distribution of Mono and Multi-drug resistance of Staphylococcus species
Out of 64 Staphylococcal isolates, only one (1.56%) isolate of Staphylococcus (S. aureus) was susceptible to all antimicrobial agents tested, while two (3.13%) isolates of Staphylococcus were mono drug resistant. Multi-drug resistance to three or more antimicrobials was observed in 61 (95.31%) of all the isolates (Table 5).
Table 5
Number and percentages of antimicrobial resistance patterns of Staphylococcus species
No of antimicrobials | Antimicrobial resistance pattern | Number (%) | Species |
One | NA | 1 (1.56) | SH |
| P | 1 (1.56) | SA |
Three | P, E, S(1); P, AML, TE (1); P, E, TE(1); P, VA, TE (2); P, F, E (1); P, VA, E (1) | 7(10.94) | SA |
P, AML, TE(1) P, E, TE(1) | 2 (3.13) | SH |
Four | P, AML, E, TE (2); P, CIP, AML, NA (1) P, E, TE, NA (1) | 4 (6.25) | SH |
P, AML, F, TE (1); P, AML, E, S (1) | 2 (3.13) | CNS |
P, AML, F, TE (1) ; P, VA, AML, TE (2); P, VA, AML, E (5); P, VA, E, S (1); P, VA, TE, S (1) P, E, TE, S (1) | 11(17.19) | SA |
Five | P, CIP, AML, TE, E (1) | 1 (1.56) | SI |
P, VA, F, E, TE (2); | 2 (3.13) | SH |
P, AML, F, E, TE (1); P, VA, AML, E, TE(1); P, VA, E, TE, NA (1) | 3 (4.69) | CNS |
P, AML, F, E, TE (1); P, VA, AML, E, TE(4); P, VA, SXT, AML, TE (1); P, VA, AML, TE, S (2); P, VA, TE, S, NA (1); P, VA, E, TE, S (1); P, AML, F, TE, S (1) | 11 (17.19) | SA |
Six | P, SXT, AML, E, TE, S (1); | 1 (1.56) | SI |
P, VA, F, E, TE, S (1); | 1 (1.56) | SH |
P, VA, AML, F, E, TE (1); P, AML, F, E, TE, NA (1) | 2 (3.13) | CNS |
P, SXT, AML, E, TE, S (1); P, VA, AML, F, E, TE (1); P, VA, SXT, E, TE, S (1); P, VA, SXY, AML, TE, S (1); P, VA, AML, E, TE, S (2) | 6 (9.380) | SA |
Seven | P, SXT, AML, F, TE, S, NA (1); | 1 (1.56) | SI |
P, VA, AML, F, TE, S, NA (1); | 1 (1.56) | SH |
P, SXT, AML, F, E, TE, S (1) P, VA, AML, F, E, TE, S (1); | 2 (3.13) | CNS |
P, VA, AML, F, E, TE, S (1); P, VA, SXT, AML, E, TE, NA (1); P, VA, CIP, AML, E, TE, NA (1); | 3 (4.69) | SA |
Eight | P, VA, SXT, F, E, TE, S, NA(1) | 1 (1.56) | CNS |
Total | Mono resistance (2) Multi resistance (61) | 63 (98.44) | SA(39) SH(11) SI(3) CNS(10) |
MDR | 61 | 61 (95.31) | SA(38) SH(10) SI(3) CNS(10) |
Key: MDR = Multi drug resistance, SA = S. aureus, SH = S. hycus, SI = S. intermedius |