(404) - Clinical and Molecular Epidemiologic Characterization of Methicillin-Resistant Staphylococcus aureus (MRSA) Infections Occurring Early After Lung Transplant

Abstract

PurposeWe recently described our clinical experience with MRSA infections following lung transplant (LTx). A previous study showed that post-LTx MRSA infections were due to hospital-acquired (HA) strains. We studied the molecular epidemiology of MRSA infections in our program.MethodsRetrospective review of MRSA infections in the first 90 days after LTx at UPMC from 2008-10. Isolates were characterized by PFGE, Staphylococcal Cassette Chromosome mec (SCCmec) and spa typing, and detection of Panton-Valentine leukocidin (PVL).ResultsThe incidence of MRSA infections was 18%. 75 isolates from 17 pts were studied (median: 3/pt). Infections were caused most commonly by the HA genotype SCCmec type II (n=12 pts, spa t002 most common), and community acquired (CA) genotype SCCmec type IV, spa t008 (n=5 pts). Median time from LTx to SCCmec type II and IV infections was 18 and 16 d, respectively. 7 pts were colonized with MRSA prior to LTx (5 SCCmec type II, 2 SCCmec type IV), each of whom developed infections by the colonizing strain. Pneumonia, tracheobronchitis, and endobronchial infection were the most common infections caused by either SCCmec type II or SCCmec IV. Pts infected with type IV were more likely to have multiple sites of infection (p=0.02). Abscesses (1 lung, 1 breast, 1 parotid) developed in 3 of 5 pts infected with type IV. 2 pts (1 SCCmec type II, 1 SCCmec type IV) developed complete airway dehiscence. No pts died within 90 days of infection. Recurrent infections were caused by the same strains causing initial infections post-LTx, demonstrating the difficulty in eradicating both HA- and CA-MRSA once established. Strains were PVL(+) in 4 of 5 LTx pts with SCCmec type IV infections. All SCCmec type II isolates were PVL(-).ConclusionSCCmec type II, spa t002 (typical HA) and SCCmec type IV, spa t008 (typical CA) MRSA genotypes were both common causes of infection in the first 90 days after LTx, consistent with movement of candidates between health care and community settings. Post-LTx infections were caused by pre-LTx strains, suggesting that systematic decolonization protocols may be effective at preventing disease. Multiple sites of infection and abscesses were more common with SCCmec type IV (CA), but otherwise types of infection and clinical courses were similar for CA- and HA-strains. PurposeWe recently described our clinical experience with MRSA infections following lung transplant (LTx). A previous study showed that post-LTx MRSA infections were due to hospital-acquired (HA) strains. We studied the molecular epidemiology of MRSA infections in our program. We recently described our clinical experience with MRSA infections following lung transplant (LTx). A previous study showed that post-LTx MRSA infections were due to hospital-acquired (HA) strains. We studied the molecular epidemiology of MRSA infections in our program. MethodsRetrospective review of MRSA infections in the first 90 days after LTx at UPMC from 2008-10. Isolates were characterized by PFGE, Staphylococcal Cassette Chromosome mec (SCCmec) and spa typing, and detection of Panton-Valentine leukocidin (PVL). Retrospective review of MRSA infections in the first 90 days after LTx at UPMC from 2008-10. Isolates were characterized by PFGE, Staphylococcal Cassette Chromosome mec (SCCmec) and spa typing, and detection of Panton-Valentine leukocidin (PVL). ResultsThe incidence of MRSA infections was 18%. 75 isolates from 17 pts were studied (median: 3/pt). Infections were caused most commonly by the HA genotype SCCmec type II (n=12 pts, spa t002 most common), and community acquired (CA) genotype SCCmec type IV, spa t008 (n=5 pts). Median time from LTx to SCCmec type II and IV infections was 18 and 16 d, respectively. 7 pts were colonized with MRSA prior to LTx (5 SCCmec type II, 2 SCCmec type IV), each of whom developed infections by the colonizing strain. Pneumonia, tracheobronchitis, and endobronchial infection were the most common infections caused by either SCCmec type II or SCCmec IV. Pts infected with type IV were more likely to have multiple sites of infection (p=0.02). Abscesses (1 lung, 1 breast, 1 parotid) developed in 3 of 5 pts infected with type IV. 2 pts (1 SCCmec type II, 1 SCCmec type IV) developed complete airway dehiscence. No pts died within 90 days of infection. Recurrent infections were caused by the same strains causing initial infections post-LTx, demonstrating the difficulty in eradicating both HA- and CA-MRSA once established. Strains were PVL(+) in 4 of 5 LTx pts with SCCmec type IV infections. All SCCmec type II isolates were PVL(-). The incidence of MRSA infections was 18%. 75 isolates from 17 pts were studied (median: 3/pt). Infections were caused most commonly by the HA genotype SCCmec type II (n=12 pts, spa t002 most common), and community acquired (CA) genotype SCCmec type IV, spa t008 (n=5 pts). Median time from LTx to SCCmec type II and IV infections was 18 and 16 d, respectively. 7 pts were colonized with MRSA prior to LTx (5 SCCmec type II, 2 SCCmec type IV), each of whom developed infections by the colonizing strain. Pneumonia, tracheobronchitis, and endobronchial infection were the most common infections caused by either SCCmec type II or SCCmec IV. Pts infected with type IV were more likely to have multiple sites of infection (p=0.02). Abscesses (1 lung, 1 breast, 1 parotid) developed in 3 of 5 pts infected with type IV. 2 pts (1 SCCmec type II, 1 SCCmec type IV) developed complete airway dehiscence. No pts died within 90 days of infection. Recurrent infections were caused by the same strains causing initial infections post-LTx, demonstrating the difficulty in eradicating both HA- and CA-MRSA once established. Strains were PVL(+) in 4 of 5 LTx pts with SCCmec type IV infections. All SCCmec type II isolates were PVL(-). ConclusionSCCmec type II, spa t002 (typical HA) and SCCmec type IV, spa t008 (typical CA) MRSA genotypes were both common causes of infection in the first 90 days after LTx, consistent with movement of candidates between health care and community settings. Post-LTx infections were caused by pre-LTx strains, suggesting that systematic decolonization protocols may be effective at preventing disease. Multiple sites of infection and abscesses were more common with SCCmec type IV (CA), but otherwise types of infection and clinical courses were similar for CA- and HA-strains. SCCmec type II, spa t002 (typical HA) and SCCmec type IV, spa t008 (typical CA) MRSA genotypes were both common causes of infection in the first 90 days after LTx, consistent with movement of candidates between health care and community settings. Post-LTx infections were caused by pre-LTx strains, suggesting that systematic decolonization protocols may be effective at preventing disease. Multiple sites of infection and abscesses were more common with SCCmec type IV (CA), but otherwise types of infection and clinical courses were similar for CA- and HA-strains.