TABLE 2.
Antimicrobial resistance genes harbored by the 178 LA-MRSA-CC398 included in the study
| Resistance to: | Gene | No. of isolates | Gene combinations | No. of isolates |
|---|---|---|---|---|
| β-Lactams | blaZ | 172a | blaZ + mecA | 172 |
| mecA | 178 | |||
| Tetracyclines | tet(K) | 172 | tet(K) + tet(M) | 131 |
| tet(L) | 43 | tet(L) + tet(M) | 3 | |
| tet(M) | 177 | tet(K) + tet(L) + tet(M) | 40 | |
| tet(38) | 178b | |||
| Macrolides, lincosamides, streptogramin B | erm(A) | 23 | erm(A) + erm(B) | 5 |
| erm(B) | 39 | erm(A) + erm(C) | 4 | |
| erm(C) | 48 | erm(A) + erm(54) | 1 | |
| erm(T) | 10 | erm(B) + erm(C) | 2 | |
| erm(54) | 1 | erm(C) + erm(T) | 3 | |
| erm(A) + erm(B) + erm(C) | 1 | |||
| Lincosamides | lnu(A) | 3 | ||
| lnu(B) | 9 | |||
| Lincosamides, pleuromutilins, streptogramin A | vga(A)V | 25 | ||
| vga(A)LC | 2 | |||
| vga(C) | 1 | |||
| vga(E) | 21 | |||
| lsa(E) | 9 | |||
| Aminoglycosides | aacA-aphD (gentamicin, kanamycin, tobramycin, amikacin) | 15 | aacA-aphD + str | 1 |
| aacA-aphD + aadD + str | 9 | |||
| aadD (kanamycin, neomycin, tobramycin) | 42 | aadD + aadE | 5 | |
| aadD + str | 20 | |||
| aadE (streptomycin) | 7 | aadD + aadE + str | 2 | |
| str (streptomycin) | 82 | |||
| Aminocyclitols | spc (spectinomycin) | 24 | spc + apmA | 1 |
| spcV (spectinomycin) | 2 | spc + spw + apmA | 1 | |
| spd (spectinomycin) | 2 | |||
| spw (spectinomycin) | 7 | |||
| apmA (apramycin, decreased gentamicin susceptibility) | 20 | |||
| Trimethoprim | dfrG | 47 | ||
| dfrK | 47 | |||
| Phenicols | fexA | 16 | ||
| Phenicols, lincosamides, oxazolidinones, pleuromutilins, streptogramin A | cfr | 1 |
a
One isolate harbored two blaZ copies.
b
The tet(38) gene can be found in nearly every S. aureus genome, including phenotypically susceptible isolates, and may confer resistance to tetracycline only when overexpressed (23).