Table 3.
Distribution of antimicrobial and multidrug resistance among S. aureus isolated from canine specimens submitted to a veterinary diagnostic laboratory in Tennessee, USA (2006–2017)
| Antimicrobials | 2006–2008 | 2009–2011 | 2012–2014 | 2015–2017 | Total |
|---|---|---|---|---|---|
| Aminoglycosides | |||||
| Gentamicin | 2.5 (2/79) | 1.2 (1/86) | 0 (0/63) | 0 (0/40) | 1.1 (3/268) |
| β-lactams | |||||
| Ampicillin | 83.6 (61/73) | 91.9 (79/86) | 74.2 (69/93) | 81.4 (57/70) | 82.6 (266/322) |
| Cefoxitin | 25.6 (20/78) | 49.4 (42/85) | 42.4 (39/92) | 45.7 (32/70) | 40.9 (133/325)* |
| Oxacillin | 27.5 (22/80) | 52.3 (45/86) | 40.2 (37/92) | 40 (28/70) | 40.2 (132/328) |
| Fluoroquinolones | |||||
| Marbofloxacin | 23.4 (18/77) | 43.5 (37/85) | 28.6 (26/91) | 40.7 (22/54) | 33.6 (103/307) |
| Folate inhibitors | |||||
| TMSa | 3.8 (3/80) | 3.5 (3/86) | 2.2 (2/93) | 8.5 (6/71) | 4.2 (14/330) |
| Lincosamides | |||||
| Clindamycin | 33.8 (27/80) | 44.2 (38/86) | 33.3 (31/93) | 29.0 (20/69) | 35.4 (116/328) |
| Macrolides | |||||
| Erythromycin | 33.8 (27/80) | 55.8 (48/86) | 48.4 (45/93) | 50.7 (36/71) | 47.3 (156/330) |
| Phenicols | |||||
| Chloramphenicol | 3.8 (3/80) | 2.3 (2/86) | 2.2 (2/93) | 1.4 (1/71) | 2.4 (8/330) |
| Tetracyclines | |||||
| Tetracycline | 5.0 (4/80) | 7.0 (6/86) | 5.4 (5/93) | 8.7 (6/69) | 6.4 (21/328) |
| AMRb | 93.8 (75/80) | 95.4 (82/86) | 89.3 (83/93) | 93.0 (66/71) | 92.7 (306/330) |
| MDRc | 35.0 (28/80) | 53.5 (46/86) | 35.5 (33/93) | 39.4 (28/71) | 40.9 (135/330) |
| MRSAd | 21.6 (16/74) | 45.8 (38/83) | 40.7 (37/91) | 40.0 (26/65) | 37.4 (117/313)* |
aTrimethoprim/sulfamethoxazole
bAntimicrobial resistance
cMultidrug resistance
dMethicillin-resistant S. aureus, based on cefoxitin disk diffusion testing confirmed with positive mecA PCR
*p < 0.05, **p < 0.01, ***p < 0.0001 for Cochran-Armitage trend test