RESUMEN
BACKGROUND: Staphylococcus aureus bloodstream infections (BSI) cause significant morbidity and mortality due to the frequent antibiotic resistance, toxin and adhesin production of the bacterium. These characteristics differ significantly in methicillin resistant (MRSA) and methicillin sensitive S. aureus (MSSA) and also among isolates of different MRSA clones, contributing to the outcome of S. aureus bacteraemia. METHODS: In this study, all MRSA BSI isolates from Semmelweis University, Budapest, Hungary, isolated between 2011-2016 and the same number of matched MSSA (overall 306 isolates) were characterised in terms of antibiotic susceptibility, virulence genes, clonality and their association with all-cause 30-day mortality. Effect of patient related variables, such as age, gender and comorbidities were also investigated. RESULTS: ST22-MRSA-IV and ST5-MRSA-II were the most prevalent clones in our study. SCCmec I isolates showed the highest resistance rates and SCCmec II carried most virulence genes. Infections caused by SCCmec IV isolates were associated with the highest mortality rate (42.2%), despite the similar comorbidity rates of the different patient groups. All-cause 30-day mortality was 39.9% in the MRSA and 30.7% in the MSSA group. Increased teicoplanin MIC was associated with high mortality rate. Resistance to ciprofloxacin, erythromycin and clindamycin was common in MRSA, whereas MSSA isolates were more sensitive to all antibiotics with the exception of doxycycline. All MRSA isolates were sensitive to glycopeptides and linezolid; resistance to rifampicin and sulfamethoxazole-trimethoprim was low. MRSA isolates carried more adhesion genes, superantigens were more frequent in MSSA. Panton-Valentine leukocidin was found in 2.3% of the isolates. CONCLUSION: This study provides insight into the clonal composition and associated mortality of BSI S. aureus isolates in Hungary. The results suggest that the outcome of the infection is determined by the antibiotic resistance, genotype of the bacterium, and patient-related factors; rather than the virulence factors carried by the bacteria.
Asunto(s)
Farmacorresistencia Bacteriana Múltiple , Infecciones Estafilocócicas/microbiología , Staphylococcus aureus/clasificación , Staphylococcus aureus/efectos de los fármacos , Staphylococcus aureus/genética , Factores de Virulencia/genética , Adolescente , Adulto , Anciano , Anciano de 80 o más Años , Bacteriemia/microbiología , Niño , Preescolar , Femenino , Genotipo , Humanos , Hungría , Lactante , Recién Nacido , Masculino , Resistencia a la Meticilina , Staphylococcus aureus Resistente a Meticilina/clasificación , Staphylococcus aureus Resistente a Meticilina/genética , Persona de Mediana Edad , Mortalidad , Estudios Retrospectivos , Infecciones Estafilocócicas/genética , Centros de Atención Terciaria , Adulto JovenRESUMEN
In the last few decades, methicillin-resistant Staphylococcus aureus (MRSA) strains have become a serious health care problem. However, in the European Union/European Economic Area countries the prevalence of the invasive MRSA isolates has decreased in recent years; in Romania, the considerably high prevalence of these strains is still unchanged. In this study, 396 staphylococcal strains were screened using molecular biology techniques for the presence of the nucA, mecA, and mecI genes and for the detection of the possible mutations accumulated in the mecI gene. More than half of the collected Staphylococcus strains (59.34%) were determined as S. aureus, and 63 strains were considered as MRSA. Small number of MRSA strains (n = 6; 54.54% of invasive S. aureus) originated from hemoculture. The mecI gene was present in 22 MRSA strains and in 4 methicillin-resistant coagulase-negative staphylococci strains. The majority of the mecI-positive MRSA strains contained the C to T substitution at position 202; furthermore, one previously undescribed mutation (C to G transversion at nucleotide position 285) was detected in one MRSA strain.