Risk factors and mortality of healthcare-associated and community-acquired Staphylococcus aureus bacteraemia.

Staphylococcus aureus bacteraemia (SAB) is a leading cause of mortality and morbidity in both nosocomial and community settings. The objective of the study is to explore epidemiological characteristics and predisposing risk factors associated with healthcare-associated (HCA) and community-acquired (CA) SAB, and to evaluate any differences in mortality and efficacy of initial antimicrobial therapy on treatment outcome. We conducted a two-part analysis. First, a triple case-control study in which groups of HCA SAB with onset ≥ 48 h after hospital admission (HCA ≥ 48 h), HCA SAB with onset <48 h of hospital admission (HCA <48 h), and CA SAB were compared with controls. Second, a cohort study including all patients with SAB was performed to identify factors associated with in-hospital mortality. SAB was diagnosed in 165 patients over the study period (January 2007 to December 2007). Five variables were independently associated with HCA ≥ 48 h SAB: presence of central venous catheter, solid tumour, chronic renal failure, previous hospitalization and previous antibiotic therapy. Significant risk factors for HCA <48 h SAB were: Charlson Comorbidity Index ≥ 3, previous hospitalization, living in long-term care facilities and corticosteroid therapy. Factors independently associated with CA SAB were: diabetes mellitus, HIV infection and chronic live disease. Patients with HCA <48 h SAB were significantly more likely to receive initial inadequate antimicrobial treatment than patients with CA or HCA ≥ 48 h SAB (44.8% versus 33.3% and 31.5%, respectively). Logistic-regression analysis identified three variables as independent predictors of mortality: presentation with septic shock, infection with methicillin-resistant S. aureus, and initial inadequate antimicrobial treatment. More than half of patients with SAB have MRSA strains and presentation with septic shock, and inappropriate empirical therapy was associated with increased mortality.

Bassetti M ，Trecarichi EM ，Mesini A ，Spanu T ，Giacobbe DR ，Rossi M ，Shenone E ，Pascale GD ，Molinari MP ，Cauda R ，Viscoli C ，Tumbarello M ... -  《-》

Predisposing factors, disease progression and outcome in 430 prospectively followed patients of healthcare- and community-associated Staphylococcus aureus bacteraemia.

Staphylococcus aureus bacteraemia (SAB) episodes identified in a prospective multicentre study during 1999-2002 (not including MRSA) were followed up by an infectious disease specialist. The aim of this study was to compare predisposing factors, disease progression and outcome of healthcare (HA)- and community (CA)-associated SAB. Of 430 SAB episodes, 232 (54%) were HA. The HA-SAB patients were significantly older and more chronically ill compared to CA-SAB. Deep infection foci prevalence within three days of onset of SAB for HA versus CA were deep-seated abscesses (26% vs 37%, P < 0.05), pneumonia [25% vs 31%, non-significant (NS)], osteomyelitis (24% vs 36%, P<0.01), permanent foreign body (24% vs 9%, P<0.001), endocarditis (11% vs 15%, NS), septic arthritis (9% vs 13%, NS) and no infection focus (3% vs 6%, NS). The case fatality rates for HA-SAB versus CA-SAB at 28 days were 14% vs 11% (NS). Independent risk factors according to multivariate analysis for a fatal outcome were age, chronic alcoholism, immunosuppressive treatment, ultimately or rapidly fatal underlying diseases, severe sepsis on the onset of SAB, S. aureus pneumonia and endocarditis. As a result of a prospective study design, meticulous infection foci search and infectious disease specialist follow-up of each SAB episode, the case fatality remained low and 97% of the HA-SAB episodes presented infection foci within three days of onset of bacteraemia.

Forsblom E ，Ruotsalainen E ，Mölkänen T ，Ollgren J ，Lyytikäinen O ，Järvinen A ... -  《-》

Methicillin-resistant Staphylococcus aureus bacteraemia diagnosed at hospital admission: distinguishing between community-acquired versus healthcare-associated strains.

Tacconelli E ，Venkataraman L ，De Girolami PC ，DAgata EM ... -  《JOURNAL OF ANTIMICROBIAL CHEMOTHERAPY》

Feedback to clinicians on preventable factors can reduce hospital onset Staphylococcus aureus bacteraemia rates.

Staphylococcus aureus bacteraemia (SAB) is associated with significant morbidity and mortality, yet there are limited data on preventable factors. This study aimed to evaluate SAB episodes at a tertiary care hospital; to identify factors that, if avoided, might have prevented the episode of SAB; and to provide feedback to treating clinicians. Of 187 episodes of SAB over 19 months 59.9% were caused by meticillin-susceptible S. aureus (MSSA) and 40.1% meticillin-resistant S. aureus (MRSA), 65.8% of SAB were healthcare-associated (HA) and 34.2% were community-acquired. Seven- and 30-day mortality rates, overall, were 11.2% and 20.9% respectively. At least one preventable factor was identified in 50.4% of HA-SAB episodes, including recent nosocomial MRSA acquisition in 53.7% MRSAB episodes and one or more factors associated with intravenous access in at least 24.3% of HA (35.7% of hospital onset) cases. SAB was more likely to be associated with at least one identifiable, preventable factor in surgical than in medical inpatients (86.2% vs 54.5%, P=0.004). Patients with HA-MRSAB were more likely than those with HA-MSSAB to require intensive care unit admission (44.4% vs 18.8%, P=0.003). Identifying and addressing preventable factors will better target resources for prevention of SAB. Feedback about preventable factors was associated with a reduction in HA-SAB rates from 0.29 to 0.20 per 1000 occupied bed-days, from 2008 to 2009.

Kok J ，O'Sullivan MV ，Gilbert GL 《-》

Comparison of microbiological and clinical characteristics based on SCCmec typing in patients with community-onset meticillin-resistant Staphylococcus aureus (MRSA) bacteraemia.

Molecular identification methods based on the staphylococcal cassette chromosome mec (SCCmec) genotype are more reliable than clinical risk factors and demographic data for differentiating community-acquired and healthcare-associated (HCA) meticillin-resistant Staphylococcus aureus (MRSA). However, patients with community-onset (CO) MRSA infections, defined as a culture-positive sample obtained <48h after admission and from patients with HCA risk factors, have been infrequently studied. This study compared the clinical profiles of different SCCmec genotypes in this group of patients. From 2004 to 2008, the clinical profiles of 122 non-repetitive patients with CO-MRSA infections at a tertiary medical centre in Taiwan were retrospectively recorded and the molecular characteristics of the isolates were examined. The proportion of SCCmec IV/V genotypes increased from 9.5% to 35.3% from 2004 to 2008. There were no differences in demographic data, underlying diseases, invasive procedures or outcomes between the SCCmec II/III and IV/V groups, except that patients with SCCmec II/III genotypes tended to have more HCA risk factors (3.1 vs. 2.4; P=0.008). Multivariate logistic regression analysis revealed that having at least four HCA risk factors was independently associated with SCCmec II/III. The sensitivity of recovering SCCmec IV/V genotypes from patients with less than four HCA risk factors was 89.3%. This study revealed the emergence of SCCmec IV/V genotypes in CO-MRSA infections. Although the clinical characteristic boundaries between SCCmec II/III and IV/V diminished, having at least four HCA risk factors made the presence of SCCmec IV/V genotypes less likely in patients with CO-MRSA infections.

Kuo SC ，Chiang MC ，Lee WS ，Chen LY ，Wu HS ，Yu KW ，Fung CP ，Wang FD ... -  《-》