Stroke and endocarditis: Reversing the point of view. A retrospective, cohort study.

STUDY OBJECTIVES: The primary objective of our study is to assess the endocarditis prevalence in patients admitted to the emergency department (ED) for a primary diagnosis of acute stroke (AS). Secondary objectives are the identification of early markers of endocarditis in AS patients and the analysis of the short-term outcome of this population. METHODS: In this observational, retrospective, cohort study we enrolled consecutive adult patients with a primary diagnosis of AS admitted to the Stroke Unit or to the Neurological Intensive Care Unit of our hospital who were then discharged with a diagnosis of endocarditis. These patients were then compared with age and sex-matched controls with a diagnosis of AS and atrial fibrillation. RESULTS: Endocarditis prevalence in patients admitted to the Stroke Unit or Neurological Intensive Care Unit with a primary diagnosis of AS is 1.0% (95% confidence interval 0.61-1.55). Fever on ED admission, concomitant cancer, low hemoglobin, low lymphocyte levels, a high neutrophils count and erythrocyte sedimentation levels could early differentiate among AS patients, those with endocarditis from those with atrial fibrillation. A moderate-to-severe valvular regurgitation is strongly suggestive of endocarditis. The short term-outcome is markedly worse in endocarditis patients compared to patients with atrial fibrillation, in terms of in-hospital mortality and discharge disability. CONCLUSIONS: Endocarditis prevalence in patients admitted for a primary diagnosis of AS is low, but this etiology leads to a poor outcome. Some laboratory, clinical-epidemiological and echocardiographic parameters may help the physician to early recognize this condition and, consequently, to promptly start an antibiotic therapy.

Disentangling the Association of Hydroxychloroquine Treatment with Mortality in Covid-19 Hospitalized Patients through Hierarchical Clustering.

The efficacy of hydroxychloroquine (HCQ) in treating SARS-CoV-2 infection is harshly debated, with observational and experimental studies reporting contrasting results. To clarify the role of HCQ in Covid-19 patients, we carried out a retrospective observational study of 4,396 unselected patients hospitalized for Covid-19 in Italy (February-May 2020). Patients' characteristics were collected at entry, including age, sex, obesity, smoking status, blood parameters, history of diabetes, cancer, cardiovascular and chronic pulmonary diseases, and medications in use. These were used to identify subtypes of patients with similar characteristics through hierarchical clustering based on Gower distance. Using multivariable Cox regressions, these clusters were then tested for association with mortality and modification of effect by treatment with HCQ. We identified two clusters, one of 3,913 younger patients with lower circulating inflammation levels and better renal function, and one of 483 generally older and more comorbid subjects, more prevalently men and smokers. The latter group was at increased death risk adjusted by HCQ (HR[CI95%] = 3.80[3.08-4.67]), while HCQ showed an independent inverse association (0.51[0.43-0.61]), as well as a significant influence of cluster∗HCQ interaction (p < 0.001). This was driven by a differential association of HCQ with mortality between the high (0.89[0.65-1.22]) and the low risk cluster (0.46[0.39-0.54]). These effects survived adjustments for additional medications in use and were concordant with associations with disease severity and outcome. These findings suggest a particularly beneficial effect of HCQ within low risk Covid-19 patients and may contribute to clarifying the current controversy on HCQ efficacy in Covid-19 treatment.

Lopinavir/Ritonavir and Darunavir/Cobicistat in Hospitalized COVID-19 Patients: Findings From the Multicenter Italian CORIST Study.

Background: Protease inhibitors have been considered as possible therapeutic agents for COVID-19 patients. Objectives: To describe the association between lopinavir/ritonavir (LPV/r) or darunavir/cobicistat (DRV/c) use and in-hospital mortality in COVID-19 patients. Study Design: Multicenter observational study of COVID-19 patients admitted in 33 Italian hospitals. Medications, preexisting conditions, clinical measures, and outcomes were extracted from medical records. Patients were retrospectively divided in three groups, according to use of LPV/r, DRV/c or none of them. Primary outcome in a time-to event analysis was death. We used Cox proportional-hazards models with inverse probability of treatment weighting by multinomial propensity scores. Results: Out of 3,451 patients, 33.3% LPV/r and 13.9% received DRV/c. Patients receiving LPV/r or DRV/c were more likely younger, men, had higher C-reactive protein levels while less likely had hypertension, cardiovascular, pulmonary or kidney disease. After adjustment for propensity scores, LPV/r use was not associated with mortality (HR = 0.94, 95% CI 0.78 to 1.13), whereas treatment with DRV/c was associated with a higher death risk (HR = 1.89, 1.53 to 2.34, E-value = 2.43). This increased risk was more marked in women, in elderly, in patients with higher severity of COVID-19 and in patients receiving other COVID-19 drugs. Conclusions: In a large cohort of Italian patients hospitalized for COVID-19 in a real-life setting, the use of LPV/r treatment did not change death rate, while DRV/c was associated with increased mortality. Within the limits of an observational study, these data do not support the use of LPV/r or DRV/c in COVID-19 patients.

Heparin in COVID-19 Patients Is Associated with Reduced In-Hospital Mortality: The Multicenter Italian CORIST Study.

INTRODUCTION: A hypercoagulable condition was described in patients with coronavirus disease 2019 (COVID-19) and proposed as a possible pathogenic mechanism contributing to disease progression and lethality. AIM: We evaluated if in-hospital administration of heparin improved survival in a large cohort of Italian COVID-19 patients. METHODS: In a retrospective observational study, 2,574 unselected patients hospitalized in 30 clinical centers in Italy from February 19, 2020 to June 5, 2020 with laboratory-confirmed severe acute respiratory syndrome coronavirus-2 infection were analyzed. The primary endpoint in a time-to event analysis was in-hospital death, comparing patients who received heparin (low-molecular-weight heparin [LMWH] or unfractionated heparin [UFH]) with patients who did not. We used multivariable Cox proportional-hazards regression models with inverse probability for treatment weighting by propensity scores. RESULTS: Out of 2,574 COVID-19 patients, 70.1% received heparin. LMWH was largely the most used formulation (99.5%). Death rates for patients receiving heparin or not were 7.4 and 14.0 per 1,000 person-days, respectively. After adjustment for propensity scores, we found a 40% lower risk of death in patients receiving heparin (hazard ratio = 0.60; 95% confidence interval: 0.49-0.74; E-value = 2.04). This association was particularly evident in patients with a higher severity of disease or strong coagulation activation. CONCLUSION: In-hospital heparin treatment was associated with a lower mortality, particularly in severely ill COVID-19 patients and in those with strong coagulation activation. The results from randomized clinical trials are eagerly awaited to provide clear-cut recommendations.

Common cardiovascular risk factors and in-hospital mortality in 3,894 patients with COVID-19: survival analysis and machine learning-based findings from the multicentre Italian CORIST Study.

BACKGROUND AND AIMS: There is poor knowledge on characteristics, comorbidities and laboratory measures associated with risk for adverse outcomes and in-hospital mortality in European Countries. We aimed at identifying baseline characteristics predisposing COVID-19 patients to in-hospital death. METHODS AND RESULTS: Retrospective observational study on 3894 patients with SARS-CoV-2 infection hospitalized from February 19th to May 23rd, 2020 and recruited in 30 clinical centres distributed throughout Italy. Machine learning (random forest)-based and Cox survival analysis. 61.7% of participants were men (median age 67 years), followed up for a median of 13 days. In-hospital mortality exhibited a geographical gradient, Northern Italian regions featuring more than twofold higher death rates as compared to Central/Southern areas (15.6% vs 6.4%, respectively). Machine learning analysis revealed that the most important features in death classification were impaired renal function, elevated C reactive protein and advanced age. These findings were confirmed by multivariable Cox survival analysis (hazard ratio (HR): 8.2; 95% confidence interval (CI) 4.6-14.7 for age ≥85 vs 18-44 y); HR = 4.7; 2.9-7.7 for estimated glomerular filtration rate levels <15 vs ≥ 90 mL/min/1.73 m2; HR = 2.3; 1.5-3.6 for C-reactive protein levels ≥10 vs ≤ 3 mg/L). No relation was found with obesity, tobacco use, cardiovascular disease and related-comorbidities. The associations between these variables and mortality were substantially homogenous across all sub-groups analyses. CONCLUSIONS: Impaired renal function, elevated C-reactive protein and advanced age were major predictors of in-hospital death in a large cohort of unselected patients with COVID-19, admitted to 30 different clinical centres all over Italy.

The association of high-sensitivity c-reactive protein and other biomarkers with cardiovascular disease in patients treated for HIV: a nested case-control study.

BACKGROUND: Elevated high-sensitivity C-reactive protein (hsCRP) increases the risk of cardiovascular disease (CVD) in the general population, but its role as a predictive marker in HIV-positive patients remains unclear. Aim of the study was to evaluate whether hsCRP or other biomarkers are independent predictors of CVD risk in HIV-infected patients. METHODS: Retrospective, nested case-control study. HIV-positive men and women (35-69 years of age) receiving combination antiretroviral therapy (cART) were included. Cases (n = 35) had a major CVD event. Controls (n = 74) free from CVD events for at least 5 years from starting ART were matched on diabetes and smoking. HsCRP, D-dimer, P-selectin, interleukin-6 (IL-6), tissue plasminogen activator, plasminogen activator inhibitor-1 levels were measured. RESULTS: High hsCRP was associated with CVD risk, independently of traditional cardiovascular risk factors, HIV replication and the type of ART received at the time of sampling (adjusted odds ratio 8.00 [1.23-51.94] comparing >3.3 mg/L with <0.9 mg/L; P = 0.03). Higher IL-6 and P-selectin levels were also independently associated with increased CVD risk, although the association was weaker than for hsCRP. Higher total cholesterol and lower HDL cholesterol increased CVD risk, independent of hsCRP. CONCLUSION: hsCRP may be a useful additional biomarker to predict CVD risk in HIV-infected patients receiving cART.

2011-12 seasonal influenza vaccines effectiveness against confirmed A(H3N2) influenza hospitalisation: pooled analysis from a European network of hospitals. A pilot study.

BACKGROUND: Influenza vaccination strategies aim at protecting high-risk population from severe outcomes. Estimating the effectiveness of seasonal vaccines against influenza related hospitalisation is important to guide these strategies. Large sample size is needed to have precise estimate of influenza vaccine effectiveness (IVE) against severe outcomes. We assessed the feasibility of measuring seasonal IVE against hospitalisation with laboratory confirmed influenza through a network of 21 hospitals in the European Union. METHODS: We conducted a multicentre study in France (seven hospitals), Italy (one hospital), and Navarra (four hospitals) and Valencia (nine hospitals) regions in Spain. All ≥18 years hospitalised patients presenting an influenza-like illness within seven days were swabbed. Cases were patients RT-PCR positive for influenza A (H3N2); controls were patients negative for any influenza virus. Using logistic regression with study site as a fixed effect we calculated IVE adjusted for potential confounders. We restricted the analyses to those swabbed within four days. RESULTS: We included, 375 A(H3N2) cases and 770 controls. The overall adjusted IVE was 24.9% (95%CI-1.8;44.6). Among the target group for vaccination (N = 1058) the adjusted IVE was 28.8% (95%CI:2.8;47.9); it was respectively 36.8% (95%CI:-48.8; 73.1), 42.6% (95%CI:-16.5;71.7), 17.8%(95%CI:-40.8; 52.1) and 37.5% (95%CI:-22.8;68.2) in the age groups 18-64, 65-74, 75-84 and more than 84 years. DISCUSSION: Estimation of IVE based on the pooling of data obtained through a European network of hospitals was feasible. Our results suggest a low IVE against hospitalised confirmed influenza in 2011-12. The low IVE may be explained by a poor immune response in the high-risk population, imperfect match between vaccine and circulating strain or waning immunity due to a late season. Increased sample size within this network would allow more precise estimates and stratification of the IVE by time since vaccination and vaccine types or brands.

Chemotherapy-Induced Neutropenia in HIV Positive Patients with Lymphoma: Comparison of Pegfilgrastim with Daily Filgrastim Administration.

We retrospectively compared the incidence of neutropenia in two groups of HIV patients with lymphoma, who underwent chemotherapy supported by once-per-cycle administration of pegfilgrastim or by daily subcutaneous injection of filgrastim, respectively. Our findings indicate that pegfilgrastim and filgastrim produce similar results in preventing both neutropenia and febrile neutropenia.

Detrimental clinical interaction between ritonavir-boosted protease inhibitors and vinblastine in HIV-infected patients with Hodgkin's lymphoma.

In order to analyze the clinical relevance of the pharmacokinetic interactions between vinblastine and antiretrovirals described in literature, we evaluated all HIV-infected patients with Hodgkin's lymphoma treated with vinblastine-containing regimens and combination antiretroviral therapy, in a single clinical center. The use of protease inhibitors was independently associated with WHO grade III-IV neutropenia. Moreover, an inverse correlation between dosage of ritonavir and mean nadir neutrophil count was found. The concomitant administration of vinblastine-containing chemotherapy regimens with protease inhibitors can lead to higher levels of neutropenia than those of different classes of drugs such as nonnucleoside reverse transcriptase inhibitors or integrase inhibitors.

HIV Infection, Antiretroviral Therapy and Cardiovascular Risk.

In the last 15 years, highly active antiretroviral therapy (HAART) has determined a dramatic reduction of both morbidity and mortality in human immunodeficiency virus (HIV)-infected subjects, transforming this infection in a chronic and manageable disease. Patients surviving with HIV in the developed world, in larger number men, are becoming aged. As it would be expected for a population of comparable age, many HIV-infected individuals report a family history of cardiovascular disease, a small proportion have already experienced a cardiovascular event and an increasing proportion has diabetes mellitus. Smoking rate is very high while an increasing proportion of HIV-infected individuals have dyslipidaemia. Studies suggest that these traditional risk factors could play an important role in the development of cardiovascular disease in these patients as they do in the general population. Thus, whilst the predicted 10-year cardiovascular disease risk remains relatively low at present, it will likely increase in relation to the progressive aging of this patient population. Thus, the long-term follow-up of HIV infected patients has to include co-morbidity management such as cardiovascular disease prevention and treatment. Two intriguing aspects related to the cardiovascular risk in patients with HIV infection are the matter of current investigation: 1) while these subjects share many cardiovascular risk factors with the general population, HIV infection itself increases cardiovascular risk; 2) some HAART regimens too influence atherosclerotic profile, partly due to lipid changes. Although the mechanisms involved in the development of cardiovascular complications in HIV-infected patients remain to be fully elucidated, treatment guidelines recommending interventions to prevent cardiovascular disease in these individuals are already available; however, their application is still limited.

Fungaemia caused by Candida glabrata with reduced susceptibility to fluconazole due to altered gene expression: risk factors, antifungal treatment and outcome.

BACKGROUND: The role of Candida glabrata in fungaemia is attributed in part to its reduced susceptibility to azoles, usually due to altered expression of genes encoding drug efflux pumps. The aims of this study were to identify risk factors for fungaemia due to C. glabrata isolates with decreased susceptibility to fluconazole and to analyse the response to antifungal treatment and the clinical outcome of C. glabrata infections in hospitalized patients. METHODS: A retrospective case-case-control study was conducted at a university hospital from 2000 to 2006. Three patient groups were studied: 14 patients infected by a fluconazole-less-susceptible isolate [susceptible-dose-dependent (SDD) or resistant]; 21 patients infected by a fluconazole-susceptible (FS) isolate; and 70 uninfected controls. We measured expression of the drug efflux pump-encoding CgCDR1 and CgCDR2 genes in isolates of the two infected groups using quantitative real-time PCR. RESULTS: Multivariable analysis found that patients with prior fluconazole use [odds ratio (OR) 12.24, 95% confidence intervals (CIs) 1.77-84.39, P = 0.01], diabetes (OR 10.47, 95% CI 1.96-55.96, P = 0.006) and a central venous catheter (CVC) (OR 8.48, 95% CI 1.82-39.36, P = 0.006) were more likely to develop fungaemia due to a less-susceptible isolate. Previous surgery (OR 7.73, 95% CI 2.18-27.41, P = 0.002) was an independent risk factor for fungaemia due to a susceptible isolate, in addition to the presence of a CVC (OR 5.48, 95% CI 1.69-17.72, P = 0.004). The crude 30 day mortality rate was high for both case groups. Seven patients received inadequate antifungal treatment, including five infected by a fluconazole-resistant isolate but empirically treated with fluconazole; six of these seven patients died. Expression of the CgCDR genes was up-regulated in all fluconazole-resistant and, to a lesser extent, SDD isolates, but not in the FS isolates. CONCLUSIONS: Our data suggest that when candidaemia is suspected or detected, a more broad-spectrum antifungal drug (i.e. echinocandins or amphotericin B) should be considered as initial treatment for patients with prior azole exposure.

Biofilm production by Candida species and inadequate antifungal therapy as predictors of mortality for patients with candidemia.

Nosocomial Candida bloodstream infections rank among infections with highest mortality rates. A retrospective cohort analysis was conducted at Catholic University Hospital to estimate the risk factors for mortality of patients with candidemia. We reviewed records for patients with a Candida bloodstream infection over a 5-year period (January 2000 through December 2004). Two hundred ninety-four patients (42.1% male; mean age +/- standard deviation, 65 +/- 12 years) were studied. Patients most commonly were admitted with a surgical diagnosis (162 patients [55.1%]), had a central venous catheter (213 [72.4%]), cancer (118 [40.1%]), or diabetes (58 [19.7%]). One hundred fifty-four (52.3%) patients died within 30 days. Of 294 patients, 168 (57.1%) were infected by Candida albicans, 64 (21.7%) by Candida parapsilosis, 28 (9.5%) by Candida tropicalis, and 26 (8.8%) by Candida glabrata. When fungal isolates were tested for biofilm formation capacity, biofilm production was most commonly observed for isolates of C. tropicalis (20 of 28 patients [71.4%]), followed by C. glabrata (6 of 26 [23.1%]), C. albicans (38 of 168 [22.6%]), and C. parapsilosis (14 of 64 [21.8%]). Multivariable analysis identified inadequate antifungal therapy (odds ratio [OR], 2.35; 95% confidence interval [95% CI], 1.09 to 5.10; P = 0.03), infection with overall biofilm-forming Candida species (OR, 2.33; 95% CI, 1.26 to 4.30; P = 0.007), and Acute Physiology and Chronic Health Evaluation III scores (OR, 1.03; 95% CI, 1.01 to 1.15; P < 0.001) as independent predictors of mortality. Notably, if mortality was analyzed according to the different biofilm-forming Candida species studied, only infections caused by C. albicans (P < 0.001) and C. parapsilosis (P = 0.003) correlated with increased mortality. Together with well-established factors, Candida biofilm production was therefore shown to be associated with greater mortality of patients with candidemia, probably by preventing complete organism eradication from the blood.

Partial protective effect of CCR5-Delta 32 heterozygosity in a cohort of heterosexual Italian HIV-1 exposed uninfected individuals.

Despite multiple sexual exposure to HIV-1 virus, some individuals remain HIV-1 seronegative (exposed seronegative, ESN). The mechanisms underlying this resistance remain still unclear, although a multifactorial pathogenesis can be hypothesised. Although several genetic factors have been related to HIV-1 resistance, the homozigosity for a mutation in CCR5 gene (the 32 bp deletion, i.e. CCR5-Delta32 allele) is presently considered the most relevant one. In the present study we analysed the genotype at CCR5 locus of 30 Italian ESN individuals (case group) who referred multiple unprotected heterosexual intercourse with HIV-1 seropositive partner(s), for at least two years. One hundred and twenty HIV-1 infected patients and 120 individuals representative of the general population were included as control groups. Twenty percent of ESN individuals had heterozygous CCR5-Delta 32 genotype, compared to 7.5% of HIV-1 seropositive and 10% of individuals from the general population, respectively. None of the analysed individuals had CCR5-Delta 32 homozygous genotype. Sequence analysis of the entire open reading frame of CCR5 was performed in all ESN subjects and no polymorphisms or mutations were identified. Moreover, we determined the distribution of C77G variant in CD45 gene, which has been previously related to HIV-1 infection susceptibility. The frequency of the C77G variant showed no significant difference between ESN subjects and the two control groups. In conclusion, our data show a significantly higher frequency of CCR5-Delta 32 heterozygous genotype (p = 0.04) among the Italian heterosexual ESN individuals compared to HIV-1 seropositive patients, suggesting a partial protective role of CCR5-Delta 32 heterozygosity in this cohort.

Older age does not influence CD4 cell recovery in HIV-1 infected patients receiving highly active antiretroviral therapy.

BACKGROUND: Diagnosis of HIV infection is recently occurring with increasing frequency in middle-aged and in older individuals. As HAART became available, a minimal beneficial effect on immunological outcome in older in respect of younger subjects has been reported. In fact, both the intensity and the rapidity of the immunological response appeared to be reduced in elderly subjects. On the contrary, only few reports have indicated a similar immunological outcome both in older and younger HIV-positive subjects. Interestingly, older age did not seem to significantly affect the long-term virological outcome of HAART treated subjects. METHODS: To characterise epidemiological and clinical features of older HIV+ subjects, a prospective case-control study was performed: 120 subjects >/= 50 and 476 between 20 and 35 years were initially compared. Subsequently, to better define the impact of HAART on their viro-immunological response, 81 older were compared with 162 younger subjects. RESULTS: At baseline cases presented significantly lower TCD4+ cell number and were more frequently affected by comorbid conditions. Under HAART a statistically significant increase in TCD4+ cell number was observed in cases and controls. At multivariate analysis, there was no statistically significant difference between cases and controls regarding viro-immunological response. CONCLUSIONS: Although older subjects present a more severe HIV infection, they can achieve, under HAART, the same viro-immunological success as the younger individuals.

HIV infection, HAART, and endothelial adhesion molecules: current perspectives.

In this review we summarise the data on the effects of HIV infection and its therapy with antiretroviral drugs on adhesion molecules, considered to be potential biomarkers of endothelial cell function. This is a recent area of interest, given the unexpected associations between antiretroviral therapy, metabolic alterations of lipid profile, and the risk of cardiovascular disease in the absence of clear pathogenetic links. Although convincing prospective data are still scarce, it seems timely to elucidate the potential value of non-invasive, inexpensive tests for predicting cardiovascular risk in HIV-infected patients undergoing highly active antiretroviral therapy (HAART). Endothelial function, the most plausible link between infection, inflammation, and atherosclerosis, has been investigated since the beginning of the HIV epidemic. Increased concentrations of soluble adhesion molecules, such as those from the selectin and immunoglobulin families, have consistently been reported in HIV-positive patients. The introduction of HAART has renewed interest in the study of endothelial function in HIV-positive patients, in view of some HAART-related metabolic abnormalities (hyperlipidaemia, hyperglycaemia, fat redistribution) and several large reports of premature coronary artery disease. Whether HAART reduces endothelial injury associated with HIV infection or contributes to further endothelial cell activation is still a matter of controversy. Also unclear is whether HAART acts directly or indirectly, and if protease inhibitors and other classes of antiretroviral drugs differ in their proatherosclerotic effects. This article attempts to define the state of these emerging issues, identifies areas of controversy and of potential clinical relevance, and suggests some directions for future research.

Risk factors and predictors of mortality of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in HIV-infected patients.

OBJECTIVES: To define the incidence, risk factors and short-term predictors of mortality of methicillin-resistant Staphylococcus aureus (MRSA) bacteraemia in HIV-infected patients. PATIENTS AND METHODS: All HIV-infected subjects with S. aureus bacteraemia were consecutively enrolled in a case-control study between January 1, 1991 and December 31, 2000 and prospectively followed up. RESULTS: In the study period, 129 of 419 (31%) HIV-infected patients with bacteraemia had a diagnosis of S. aureus bacteraemia. The comparative analysis of incidence of S. aureus bacteraemia in the period 1991-96 and 1997-2000 showed a significant decrease (P < 0.001). The same trend was observed for MRSA bacteraemia (P = 0.002). The analysis of antimicrobial resistance showed that among 129 S. aureus strains, 88 (68%) were methicillin susceptible and 41 (32%) were methicillin resistant. The majority of MRSA bacteraemia was hospital acquired (78%). Previous administration of beta-lactams (P < 0.001), multiple previous hospital admissions (P < 0.001) and low numbers of CD4+ peripheral cells (P < 0.001) were found to be independent risk factors of methicillin resistance at multivariate analysis. The mortality rate was 34% in the cases and 11% in the controls (P = 0.002). Multivariate analysis indicated that a high Acute Physiology and Chronic Health Evaluation (APACHE) III score (P < 0.001) and high HIV viraemia (P = 0.02), but not methicillin resistance, predicted an increased risk of death in patients with S. aureus bacteraemia. CONCLUSION: Individual exposure to beta-lactams, in association with a history of multiple hospitalizations and low CD4+ cell number, plays a pivotal role as a risk factor for the development of methicillin resistance in HIV-infected patients. Methicillin resistance does not influence the outcome of S. aureus bacteraemia when included in a multivariate analysis.