Persistent and recurrent bacteremia caused by Staphylococcus aureus: Clinical, microbiological and molecular analysis

PERAZZI B; DI GREGORIO S; DE GREGORIO S; ORDOÑEZ MARTINEZ A; BELLO N; FOCCOLI M; GARCÍA S; VAY C; LASALA MB; MOLLERACH M; FAMIGLIETTI A

Denver

Conferencia; 53rd Interscience Conference on Antimicrobial Agents and Chemotherapy; 2013

American Society for Microbiology

Objective: To evaluate the clinical, microbiological and molecular characteristics of the isolates recovered from patients with persistence (PBSA) and recurrence of bacteremia (RBSA) by S. aureus. Methods: We conducted a prospective, observational and transversal study including all S. aureus recovered from bloodstream infections of inpatients from August 2009 to November 2010. PBSA was defined as bacteremia of more than 7 days long duration, and RBSA as the return of S. aureus after documentation of negative blood cultures or clinical improvement after completing a course of antistaphylococcal therapy. Genotyping included SCCmec, agr typing and the detection of luk-PV genes. PFGE was used to differentiate relapse from reinfection. Heterogeneous vancomycin intermediate S. aureus (hVISA) was identified by population analysis profiling-area under the curve (PAP-AUC). Results: A total of 97 patients with S. aureus bacteremia were enrolled and 13 patients (13.4%) had multiple episodes of bacteremia by S. aureus. In this group of patients, 15 episodes were described: 5 PBSA (4.8%), and 10 RBSA (95%). Within PBSA 2 MSSA, 2 MRSA-SCCmec I-luk-PV negative-agr II, being one of them hVISA, and 1 MRSA-SCCmec IV-luk-PV positive-agr untypeable were found. By PFGE 8/10 RBSA paired isolates and 2/2 PBSA paired isolates were isogenic, indicating 8 relapses and 2 reinfections within RBSA. In the group of relapses, 4 dyalisis catheter-related bacteremia by MSSA; and 3 MRSA-SCCmec I-luk-PV negative corresponding to unknown focus, dialysis catheter-related bacteremia and empyema secondary to an undetected focus, and 1 MRSA-SCCmec IV-luk-PV negative-agr II that resulted to be hVISA corresponding to unknown focus.hVISA was detected in 2/15 (13%) episodes of PBSA and RBSA, while only one out of 90 episodes without persistence or recurrence was hVISA (1.1%). Conclusion: Different genotypes were associated with PBSA and RBSA. Although not always the episodes of persistence and recurrence were associated to the presence of hVISA strains, these were more frequent in these clinical situations.