Table 2. Univariable analysis of medical and surgical risk factors for MRSA versus MSSA infections in dogs, United States and Canada, 2001–2007*.
| Variable† | MRSA, no. (%) dogs, n = 40 | MSSA, no. (%) dogs, n = 80 | Odds ratio (95% CI) | p value‡ |
|---|---|---|---|---|
| Received antimicrobial drugs | ||||
| No | 8 (20.0) | 30 (37.5) | Ref | |
| Yes | 26 (65.0) | 33 (41.3) | 3.84 (1.21–14.74) | 0.02 |
| Don’t know |
6 (15.0) |
17 (21.2) |
1.29 (0.28–5.65) |
0.75 |
| Received >2 antimicrobial drugs | ||||
| No | 25 (62.5) | 56 (70.0) | Ref | |
| Yes | 9 (22.5) | 7 (8.8) | 2.87 (0.81–11.49) | 0.08 |
| Don’t know |
6 (15.0) |
17 (21.2) |
0.79 (0.19–2.79) |
0.78 |
| Received an aminoglycoside | ||||
| No | 8 (20.0) | 30 (37.5) | Ref | |
| Yes | 1 (2.5) | 1 (1.3) | 5.71 (0.06–517.45) | 0.30 |
| Other classes§ | 25 (62.5) | 32 (40.0) | 3.80 (1.19–14.62) | 0.02 |
| Don’t know |
6 (15.0) |
17 (21.2) |
1.29 (0.28–5.62) |
0.75 |
| Received a β-lactam | ||||
| No | 8 (20.0) | 30 (37.5) | Ref | |
| Yes | 18 (45.0) | 25 (31.3) | 3.58 (1.04–14.79) | 0.04 |
| Other classes | 8 (20.0) | 8 (10.0) | 4.18 (0.96–20.88) | 0.04 |
| Don’t know |
6 (15.0) |
17 (21.2) |
1.31 (0.28–5.69) |
0.75 |
| Received chloramphenicol | ||||
| No | 8 (20.0) | 30 (37.5) | Ref | |
| Yes | 1 (2.5) | 2 (2.5) | 2.61 (0.04–65.5) | 1.00 |
| Other classes | 25 (62.5) | 31 (38.8) | 3.84 (1.21–14.74) | 0.02 |
| Don’t know |
6 (15) |
17 (21.2) |
1.29 (0.28–5.65) |
0.75 |
| Received a fluoroquinolone | ||||
| No | 8 (20.0) | 30 (37.5) | Ref | |
| Yes | 9 (22.5) | 7 (8.8) | 5.34 (1.24–27.38) | 0.01 |
| Other classes | 17 (42.5) | 26 (32.5) | 3.24 (0.94–13.2) | 0.06 |
| Don’t know |
6 (15.0) |
17 (21.2) |
1.31 (0.29–5.74) |
0.75 |
| Received a lincosamide | ||||
| No | 8 (20.0) | 30 (37.5) | Ref | |
| Yes | 2 (5.0) | 2 (2.5) | 4.43 (0.27–75.86) | 0.19 |
| Other classes | 24 (60.0) | 31 (38.8) | 3.77 (1.18–14.53) | 0.02 |
| Don’t know |
6 (15.0) |
17 (21.2) |
1.32 (0.29–5.73) |
0.75 |
| Received a nitroimidazole | ||||
| No | 8 (20.0) | 30 (37.5) | Ref | |
| Yes | 2 (5.0) | 0 | 7.18 (0.53–∞) | 0.07 |
| Other classes | 24 (60.0) | 33 (41.3) | 3.47 (1.08–13.33) | 0.03 |
| Don’t know |
6 (15.0) |
17 (21.2) |
1.38 (0.29–6.17) |
0.74 |
| Received a tetracycline | ||||
| No | 8 (20.0) | 30 (37.5) | Ref | |
| Yes | 2 (5.0) | 1 (1.3) | 6.63 (0.29–463.75) | 0.17 |
| Other classes | 24 (60.0) | 32 (40.0) | 3.54 (1.11–13.65) | 0.03 |
| Don’t know |
6 (15.0) |
17 (21.2) |
1.33 (0.29–5.88) |
0.74 |
| Hospitalized | ||||
| No | 16 (40.0) | 38 (47.5) | Ref | |
| Yes | 16 (40.0) | 25 (31.3) | 1.54 (0.58–4.14) | 0.37 |
| Don’t know |
8 (20.0) |
17 (21.3) |
1.17 (0.32–4.06) |
0.08 |
| Underwent surgical procedure | ||||
| No | 25 (62.5) | 46 (57.5) | Ref | |
| Yes | 10 (25.0) | 16 (20.0) | 1.07 (0.39–2.83) | 1.00 |
| Don’t know | 5 (12.5) | 18 (22.5) | 0.45 (0.09–1.68) | 0.26 |
*MRSA, methicillin-resistant Staphylococcus aureus; MSSA, methicillin-susceptible Staphylococcus aureus; CI, confidence interval; Ref, referent category. Dogs with MRSA (case-patients) and MSSA (controls) infections were matched for veterinary referral hospital and date of admission. †Information obtained refers to the 90 days before admission to the veterinary referral hospital. ‡Score method for estimating p values does not assume a symmetrical distribution for discrete data. p<0.05 was considered significant. §Refers to dogs given antimicrobial drugs from other drug classes.