Association between Accessory Gene Regulator Polymorphism and Mortality among Critically Ill Patients Receiving Vancomycin for Nosocomial MRSA Bacteremia: A Cohort Study.

Background. Polymorphism of the accessory gene regulator group II (agr) in methicillin-resistant Staphylococcus aureus (MRSA) is predictive of vancomycin failure therapy. Nevertheless, the impact of group II agr expression on mortality of patients with severe MRSA infections is not well established. Objective. The goal of our study was to evaluate the association between agr polymorphism and all-cause in-hospital mortality among critically ill patients receiving vancomycin for nosocomial MRSA bacteremia. Methods. All patients with documented bacteremia by MRSA requiring treatment in the ICU between May 2009 and November 2011 were included in the study. Cox proportional hazards regression was performed to evaluate whether agr polymorphism was associated with all-cause in-hospital mortality. Covariates included age, APACHE II score, initial C-reactive protein plasma levels, initial serum creatinine levels, vancomycin minimum inhibitory concentration, vancomycin serum levels, and time to effective antibiotic administration. Results. The prevalence of group I and group II agr expression was 52.4% and 47.6%, respectively. Bacteremia by MRSA group III or group IV agr was not documented in our patients. The mean APACHE II of the study population was 24.3 (standard deviation 8.5). The overall cohort mortality was 66.6% (14 patients). After multivariate analysis, initial plasma C-reactive protein levels (P = 0.01), initial serum creatinine levels (P = 0.008), and expression of group II agr (P = 0.006) were positively associated with all-cause in-hospital mortality. Patients with bacteremia by MRSA with group II agr expression had their risk of death increased by 12.6 times when compared with those with bacteremia by MRSA with group I agr expression. Conclusion. Group II agr polymorphism is associated with an increase in mortality in critically ill patients with bacteremia by MRSA treated with vancomycin.

Vancomycin-resistant Enterococcus faecium Bacteremia in a tertiary care hospital: epidemiology, antimicrobial susceptibility, and outcome.

Vancomycin-resistant Enterococcus faecium (VREF) has emerged as a relevant multidrug-resistant pathogen and potentially lethal etiology of health care associated infections worldwide. The objective of this retrospective cohort study was to assess factors associated with mortality in patients with VREF bacteremia in a major tertiary referral hospital in Southern Brazil. All documented cases of bacteremia identified between May 2010 and July 2012 were evaluated. Cox regression was performed to determine whether the characteristics related to the host or antimicrobial treatment were associated with the all-cause 30-day mortality. In total, 35 patients with documented VREF bacteremia were identified during the study period. The median APACHE-II score of the study population was 26 (interquartile range: 10). The overall 30-day mortality was 65.7%. All VREF isolates were sensitive to linezolid, daptomycin, and quinupristin-dalfopristin. Linezolid was the only antimicrobial agent with in vitro activity against VREF that was administered to the cohort. After multivariate analysis, linezolid treatment (HR, 0.08; 95% CI, 0.02-0.27) and presence of acute kidney injury at the onset of bacteremia (HR, 4.01; 95% CI, 1.62-9.94) were independently associated with mortality. Presentation with acute kidney injury and lack of treatment with an effective antibiotic poses risk for mortality in patients with VREF bacteremia.

Prevalence and acquisition of MRSA amongst patients admitted to a tertiary-care hospital in Brazil.

BACKGROUND: There are few studies in Brazil that address baseline prevalence of MRSA colonization and associated risk factors at hospital admission, or the incidence of nosocomial colonization. We report a prospective study in a tertiary-care, university-affiliated hospital to implement a new MRSA control policy at the institution. METHODS: A cohort of randomly selected patients admitted to emergency and clinical wards at our hospital was followed until discharge. Nasal swabs were taken for identification of MRSA-colonized patients and detection of SCCmecA in positive cultures, at admission and weekly thereafter. Multivariate analysis using a log-binomial analysis was used to identify risk factors for colonization. RESULTS: After screening 297 adult patients and 176 pediatric patients, the prevalence of MRSA at admission was 6.1% (95%CI, 3.6% to 9.4%), in the adult population and 2.3% (95%CI, 0.6% to 5.7%), for children. From multivariate analysis, the risk factors associated with colonization in adults were: age above 60 years (P = 0.019) and hospitalization in the previous year (P = 0.022). Incidence analysis was performed in 276 MRSA-negative patients (175 adults and 101 children). Acquisition rate was 5.5/1,000 patient-days for adults (95%CI, 3.4 to 8.5/1,000 patients-days), and 1.1/1,000 patient-days for children (95%CI, 0.1 to 4.0/1,000 patients-days). CONCLUSIONS: The identification of MRSA carriers is a step towards establishing a control policy for MRSA, and helps to identify measures needed to reduce colonization pressure and to decrease the high acquisition rate in hospitalized patients.

Tumor necrosis factor alpha in experimental empyema thoracis.

PURPOSE: To determine serum and pleural concentrations of tumor necrosis factor alpha (TNF-α) in an experimental model of empyema induced by intrapleural inoculation of Staphylococcus aureus or Streptococcus pneumoniae. METHODS: Wistar rats were inoculated with S. aureus (SA group, 17 animals) or S. pneumoniae (SP group, 30 animals). The presence of free fluid or pus in the pleural space was investigated. TNF-α levels >150 pg/ml (minimum detection limit) were determined in pleural fluid and blood. Histopathological examination of pleural tissue was performed to determine the severity of infection. RESULTS: Serum TNF-α was >150 pg/ml in nine SA versus 10 SP rats. In pleural fluid, TNF-α was >150 pg/ml in 11 SA versus 19 SP rats. Pleural and serum TNF-α concentrations were significantly different in the SP group (P = 0.035), but not in the SA group (P = 0.727). Pleural TNF-α was similar in both groups (P = 0.92), but serum TNF-α was significantly higher in SA (P = 0.03). Out of 17 SA animals, 1 (5.8%) did not develop empyema, versus 4 (13.3%) out of 30 SP animals. A mild inflammatory response was predominant in both groups, but the inflammatory process was significantly more severe in SP (P = 0.012). However, TNF-α levels were not associated with severity of the inflammatory response. CONCLUSIONS: We describe a simple and effective rat model of empyema. TNF-α levels above 150 pg/ml in the pleural fluid are useful to confirm empyema, but cannot predict the severity of the inflammatory response. TNF-α levels below 150 pg/ml are useful to rule out empyema.

Relação do uso de cateter com a ocorrência de sepse / The relationship between catheter use and the incidence of sepsis

O objetivo deste artigo é relacionar o uso de cateteres com a ocorrência de bacteremia e sepse. A cultura foi considerada positiva quando houve crescimento de 15 ou mais colônias em placa. A identificação bacteriana foi realizada através de provas bioquímicas ou através do sistema MicroScan (Dade Behring). As hemoculturas foram incubadas e monitoradas pelo sistema Bact Alert (Organon teknika). Do total de 79 cateteres, 30,3% tiveram uma cultura positiva (24/79). Em 11,4% dos casos, o mesmo microorganismo foi detectado tanto na cultura de cateteres quanto na hemocultura, sinalizando uma bacteremia devida ao cateter (9/79). Os parâmetros bioquímicos analisados não apresentaram diferenças significativas, enquanto que os parâmetros hematológicos (leucócitos, diferencial de bastonados e plaquetas) apresentaram diferenças significativas, demonstrando serem bons marcadores para o quadro séptico. Estes achados demonstraram uma importante relação entre a utilização de cateteres intravasculares e o desenvolvimento de bacteremia e sepse.