Denise Pires Machado

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

BackgroundThere 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.MethodsA 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.ResultsAfter 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).ConclusionsThe 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.

Extended-spectrum beta-lactamases in Klebsiella spp and Escherichia coli obtained in a Brazilian teaching hospital: detection, prevalence and molecular typing

His study was performed to compare the methods of detection and to estimate the prevalence of extendedspectrum β-lactamases (ESBL) among Klebsiella spp and E. coli in a university hospital in southern Brazil. We also used a molecular typing method to evaluate the genetic correlation between isolates of ESBL K. pneumoniae. Production of ESBL was investigated in 95 clinical isolates of Klebsiella spp and Escherichia coli from Hospital de Clinicas de Porto Alegre, using Kirby-Bauer zone diameter (KB), double-disk diffusion (DD), breakpoint for ceftazidime (MIC CAZ), increased zone diameter with clavulanate (CAZ/CAC) and ratio of ceftazidime MIC/ceftazidime-clavulanate MIC (MIC CAZ/CAC). Molecular typing was performed by DNA macrorestriction analysis followed by pulsed-field gel electrophoresis. The KB method displayed the highest rates of ESBL (up to 70% of Klebsiella and 59% of E. coli), contrasting with all the other methods (p < 0.05). The confirmatory methods (DD, MIC CAZ, CAZ/CAC and MIC CAZ/CAC) showed a range of ESBL production from 8 to 13% for E. coli and from 33 to 40% for Klebsiella species. Therefore, the KB method was useful only as a screening method as it provided several false positive results. Molecular typing of 17 ESBL K. pneumoniae indicated that the isolates had no clonal relation. We found a good correlation among the confirmatory methods for ESBL detection although the methods which evaluate inhibition of the β-lactamase by clavulanate appeared to be more specific. The high prevalence of ESBL Klebsiella in our hospital is probably due to individual selection of resistant strains rather than the transmission of a common strain.

Hand hygiene, and not ertapenem use, contributed to reduction of carbapenem-resistant Pseudomonas aeruginosa rates.

OBJECTIVE To evaluate the impact of ertapenem use in Pseudomonas aeruginosa carbapenem resistance, taking into account the volume of antimicrobial consumption, the consumption by the entire hospital of alcohol-based antiseptic hand rub, and the density rate of invasive practices. DESIGN Before-and-after trial. SETTING A tertiary care university hospital in southern Brazil. METHODS Ertapenem was first added to the hospital formulary in June 2006, and it was excluded in February 2009. We evaluated Pseudomonas aeruginosa resistance rates through 3 study periods: period 1, before ertapenem use (17 months); period 2, during ertapenem use (33 months); and period 3, after exclusion of ertapenem (15 months). RESULTS After introduction of ertapenem, there was a significant decrease in median consumption of imipenem or meropenem, from 2.6 to 2.2 defined daily doses (DDDs) per 100 patient-days (level change from 0.04 to -1.08; P < .01), and an increase in the use of these medications after ertapenem exclusion, from 2.2 to 3.3 DDDs per 100 patient-days (level change from -0.14 to 0.91; P < .01), by segmented regression analysis. There was no difference in the incidence density of carbapenem-resistant P. aeruginosa infection related to ertapenem use throughout the study periods. However, by multiple regression analysis, the reduction in the rate of carbapenem-resistant P. aeruginosa infection correlated significantly with the increase in the volume of alcohol used as hand sanitizer, which was from 660.7 mL per 100 patient-days in period 1 to 2,955.1 mL per 100 patient-days in period 3 (P = .04). Ertapenem use did not impact the rate of carbapenem-resistant P. aeruginosa infection. CONCLUSIONS Use of alcohol-based hand gel, rather than ertapenem, was associated with a reduction in the rates of carbapenem-resistant P. aeruginosa infection. Measures to reduce resistance must include factors other than just antimicrobial stewardship programs alone.

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.

Vancomycin minimal inhibitory concentration from broth microdilution and Etest in respiratory tract samples of patients with ventilation-associated pneumonia

additive effect on quinolone susceptibility.7 Though Qnr proteins and Aac(60)-Ib-cr only induce low level quinolone resistance, they are known to facilitate selection of resistancemutations in the presence of concentrations of quinolone antibiotics.8 We describe an isolate of K. pneumoniae isolate carrying three plasmid-mediated quinolone-resistant genes (qnrB, qnrS and aac (60)-Ib-cr variant) together with a novel variant of gyrA gene that has not been reported previously. These mechanisms were likely to have contributed individually to the high level ciprofloxacin and levofloxacin resistance.

The impact of serum vancomycin levels and minimum inhibitory concentrations of methicillin-resistant Staphylococcus aureus on mortality in patients with nosocomial pneumonia

BACKGROUND Vancomycin is the treatment of choice for methicillin-resistant Staphylococcus aureus (MRSA) infections; however, treatment failure is not uncommon, even when the minimum inhibitory concentration (MIC) of the MRSA strain is within the susceptible range for vancomycin. OBJECTIVE To describe the relationship between molecular markers such as the mecA and agrII genes, serum vancomycin levels and vancomycin MICs, and the 30-day mortality rate of patients with nosocomial MRSA pneumonia in an intensive care unit (ICU). METHODS The present study was a prospective cohort study including all patients with MRSA hospital-acquired pneumonia or ventilator-associated pneumonia who were admitted to the ICU of a tertiary care hospital between June 2009 and December 2011. The MIC for vancomycin was determined using the E-test and broth microdilution methods. Variables analyzed included age, sex, comorbid conditions, serum vancomycin trough concentration, the Acute Physiology and Chronic Health Evaluation II (APACHE) score and the presence of the agrII gene. The primary outcome was mortality at 30 days. RESULTS Thirty-six (42.4%) patients died within 30 days of the index MRSA culture. A multiple regression analysis that included the variables of MIC (determined using the E-test or broth microdilution methods), APACHE II score, serum vancomycin level and the presence of agrII revealed that only the APACHE II score was related to the 30-day mortality rate (P=0.03). Seven patients (9.0%) with isolates exhibiting an MIC ≥1.5 μg/mL according to the E-test method died, and nine patients (11.6%) survived (P=0.76). Of the patients for whom MICs were determined using the broth microdilution method, 11 (14.1%) patients with MICs of 1.0 μg/mL died, and 16 (20.5%) survived (P=0.92). The median APACHE II score of survivors was 22.5, and the median score of nonsurvivors was 25.0 (P=0.03). The presence of the agrII gene was not related to the 30-day mortality rate. CONCLUSIONS Patients with severe hospital-acquired pneumonia presented with MRSA isolates with low to intermediate vancomycin MICs in the ICU setting. At the Hospital de Clínicas de Porto Alegre (Porto Alegre, Brazil), the 30-day mortality rate was high, and was similar among patients with severe hospital-acquired pneumonia infected with MRSA isolates that exhibited MICs of ≤1.5 μg/mL determined using the E-test method and ≤1.0 μg/mL determined using the broth microdilution method in those who achieved optimal serum vancomycin levels. The APACHE II scores which provides an overall estimate of ICU mortality were independently associated with mortality in the present study, regardless of the MICs determined. Molecular markers, such as the agrII gene, were not associated with higher mortality in the present study.

Over 18 h to positivity in the BacT/ALERT system with clustered Gram-positive cocci is highly predictive of coagulase-negative staphylococci

Coagulase-negative staphylococci (CoNS) are the most common bacteria isolated from blood cultures, but a great proportion of them are most likely contaminants.1,2 On the other hand, one single positive blood culture for Staphylococcus aureus is usually sufficient to diagnose bacteraemia. Therefore, a rapid method of differentiating CoNS from S aureus would assist in the clinical decision on starting antimicrobial treatment in a timely manner. As many laboratories routinely process blood culture bottles in automated systems that record time to positivity (TTP) and this information is readily available along with the Gram-smear results, we assessed the predictive value of TTP for the exclusion of S aureus in the setting of a positive result for clustered Gram-positive cocci.1,3,4 For this purpose, we retrospectively analysed all blood cultures collected from patients between January 2005 and February 2006 in a large university teaching hospital. In our hospital, we routinely collected two blood cultures for every patient, each one consisting of a single BacT/ALERT FA aerobic bottle. The sets …

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.

280Association between acessory gene regulator II expression and mortality among critically ill patients receiving vancomycin for hospital-acquired methicillin-resistant Staphylococcus aureus bacteremia

280. Association between acessory gene regulator II expression and mortality among critically ill patients receiving vancomycin for hospitalacquired methicillin-resistant Staphylococcus aureus bacteremia Regis Rosa, MD, MS; Eduardo Turra; Denise Machado, PhD; Angelica Cechinel; Rodrigo Dos Santos, MD, PhD; Luciano Goldani, PhD, MD; PPG Em Ciências Médicas, Ufrgs Faculty of Medicine, Porto Alegre, Brazil; Universidade Federal do Rio Grande do Sul, Porto Alegre, Brazil; Ufrgs, Porto Alegre, Brazil; Hospital de Clinicas de Porto Alegre / Universidade Federal do Rio Grande do Sul, Prto Alegre, Brazil; Infectious Diseases Unit, Hospital de Clinicas de Porto Alegre, Porto Alegre, Brazil