Volume 20, Number 5—May 2014
Letter
Linezolid-Resistant Staphylococcus epidermidis, Portugal, 2012
Table
Epidemiologic features and antimicrobial drug resistance of linezolid -resistant Staphylococcus epidermidis isolates from a hospital, Portugal, 2012*
| Characteristic | Patient no.† |
||||
|---|---|---|---|---|---|
| 1 | 2 | 3 | 4 | 5 | |
| Epidemiologic features | |||||
| Date of isolation | 2012 May 8 | 2012 Aug 7 | 2012 Oct 23 | 2012 Nov 7 | 2012 Nov 11 |
| Hospital ward | Men’s surgery | Unknown | Medicine I | Emergency unit‡ | Emergency unit‡ |
| Pathology | Gastric neoplasia§¶ | Unknown | Multiple§ | Acute lung edema | Multiple |
| Clinical sample | Catheter | Blood | Catheter | Blood | Blood |
| Patient sex/age, y | M/75 | Unknown | F/87 | M/78 | M/87 |
| Previous linezolid | Yes | Unknown | Yes# | Yes‡ | Yes‡ |
| PFGE type | A | A | A | A | A |
| Sequence type | 2** | ||||
| Biofilm production (OD570nm) |
Strong (2.33 ± 0.34)**†† |
||||
| Drug resistance | |||||
| Linezolid (MIC, mg/L) | R (32) | R (32) | R (32) | R (32) | R (32) |
| Vancomycin (MIC, mg/L) | S (2) | S (2) | S (2) | S (2) | S (2) |
| Cefoxitin | R | R | R | R | R |
| Gentamicin | R | R | R | R | R |
| Tobramycin | R | R | R | R | R |
| Ciprofloxacin | R | R | R | R | R |
| Clindamycin | R | R | R | R | R |
| Erythromycin | S | I | S | I | S |
| Quinupristin–dalfopristin | S | S | S | S | S |
| Chloramphenicol | R | R | R | R | R |
| Tetracycline | S | S | S | S | S |
| Cotrimoxazole |
R |
R |
R |
R |
R |
| Molecular features | |||||
| cfr gene | – | – | – | – | – |
| 23S rRNA mutations | |||||
| T2504A | + | + | + | + | + |
| G2631T | + | + | + | + | + |
| T2530A | + | + | + | + | + |
| L3 ribosomal protein mutations | |||||
| Leu94Val | +** | ||||
| Gly152Asp | +** | ||||
| Asp159Glu | +** | ||||
| Ala160Pro | +** | ||||
| L4 or L22 ribosomal protein mutations | None | ||||
*PFGE, pulsed-field gel electrophoresis; OD, optical density; R, resistant; S, susceptible; I, Intermediate resistance; –, negative; +, positive. Blank cells indicate not tested.
†A sixth linezolid-resistant S. epidermidis isolate was detected in December 2012; however, access to this isolate was not possible during this study.
‡Patients 4 and 5 were hospitalized in Medicine II a month before linezolid-resistant S. epidermidis was isolated. Therapy with linezolid was started during this first hospitalization. For patient 4, duration of linezolid therapy was at least 12 d. For patient 5, duration of therapy is unknown.
§Long-stay hospitalization.
¶Followed up in oncology ward since 2011.
#Patient 3 received linezolid for 11 d before linezolid-resistant S. epidermidis was detected.
**Studied in S. epidermidis from patient 1 only, representative isolate of the PFGE type A.
††For the interpretation of the results, the cutoff optical density (ODc) was defined as 3 SDs above the mean OD of the negative control (culture medium). Strains were classified as nonadherent (OD<ODc), weakly adherent (ODc<OD<2×ODc), moderately adherent (2xODc<OD<4×ODc), or strongly adherent (4×ODc<OD).