TABLE 3.
Macrolide resistance phenotypes and their association with tetracycline and erythromycin resistance genes, the int-Tn gene, serotypes, PFGE types, and restriction types of the tet(M) gene in 65 tetracycline- and erythromycin-resistant isolates of S. pneumoniae
| Macrolide resistance phenotype (n) | Resistance genea
|
int-Tn gene | No. of strains | Serotype(s) (no. of strains)b | PFGE type(s) (no. of strains)b,c | Restriction type of tet(M) loci (no. of strains)b,d | |||
|---|---|---|---|---|---|---|---|---|---|
| tet(M) | erm(B) | mef(A) | mef(E) | ||||||
| cMLS (14) | + | + | − | − | + | 12 | 23F (3), 19F (3), 14 (2), 3, 6B, 9A, 15A | b (2), d (2), c, Ost (7) | A (4), E (3), G (3), B (2) |
| + | + | + | − | + | 1 | 19A | Ost | C | |
| + | + | − | − | − | 1 | 6B | Ost | A | |
| iMcLS (44) | + | + | − | − | + | 38 | 19A (8), 23F (7), 19F (5), 6B (3), 3 (2), 6A (2), 10A (2), 10F (2), 14 (2), 15A, 33F, 36 | a (4), c (2), e (2), f (2), i (2), b, h, j, Ost (23) | A (22), C (5), D (4), B (3), F (3), E |
| + | + | − | + | + | 4 | 6B, 7F, 19F, 23F | a, b, g, h | A, B, C, D | |
| + | + | + | − | + | 1 | 3 | g | A | |
| + | + | − | − | − | 1 | 6B | Ost | A | |
| iMLS (1) | + | + | − | − | + | 1 | 23F | Ost | A |
| M (6) | + | − | − | + | + | 4 | 6B, 11A, 19A, 23F | j, Ost (3) | B (3), D |
| + | − | + | − | + | 1 | 14 | Ost | B | |
| − | − | + | − | − | 1e | 14 | Ost | ||
tet(K), tet(L), tet(O), and erm(A) were not detected in any test strain. +, present; −, absent.
The number of strains is indicated for types represented by more than one strain.
Ost, one-strain type.
Restriction profiles were as follows (different profiles yielded by the same endonucleases are distinguished by subscript numerals): A, RsaI1, MseI, TaqI, AciI1; B, RsaI2, MseI, TaqI, AciI2; C, RsaI2, MseI, TaqI, AciI3; D, RsaI1, MseI, TaqI, AciI3; E, RsaI1, MseI, TaqI, AciI4; F, RsaI2, MseI, TaqI, AciI1; G, RsaI1, MseI, TaqI, AciI5.
This strain was the only kanamycin-susceptible isolate and was also found to be susceptible to minocycline.