TABLE 3.
Nucleotide differences identified in rifampin- and spectinomycin-resistant isolates of C. psittaci 6BC and C. trachomatis L2
| Mutant strain | No. of independent mutations analyzed
|
Characteristic of mutant allelea
|
MIC | ||||
|---|---|---|---|---|---|---|---|
| Total | Distribution | Designation | Nucleotide change | Representative chlamydial mutant | Allele distribution in drug-resistant organisms | ||
| C. trachomatis L2 Rifr | 1 | 1 | rpoB1 | GAU→GGU (Asp516→Gly) | L2R1 | Mycobacterium tuberculosis, Helicobacter pylori | 800 ng/ml |
| C. psittaci 6BC Rifr | 1 | 1 | rpoB2 | AUG→AUC (Met515→Ile) | BCR1 | M. tuberculosis | 300 ng/ml |
| C. psittaci 6BC Spcr | 59 | 52 | 16S1 | C1192U | BC0E1 | E. coli, Neisseria sp., Nicotiana tabacum chloroplasts | >10 mg/mlb |
| 5 | 16S2 | A1191G | BC0A2 | Chlamydomonas reinhardtii chloroplasts | >10 mg/mlb | ||
| 1 | 16S3 | C1192G | BCS18 | E. coli | >10 mg/mlb | ||
| 1 | 16S4 | G1193C | BCS34 | Not previously reported | 5 mg/ml | ||
a
Each distinct mutation identified was given an allele name (designation), which represents a specific change (E. coli numbering) at the indicated nucleotide in the rpoB or 16S rRNA sequence.
b
Spc concentrations above 10 mg/ml were cytotoxic to mouse fibroblast cells in the monolayer.