A hospital-based matched case-control study to identify clinical outcome and risk factors associated with carbapenem-resistant Klebsiella pneumoniae infection

Background: Healthcare-associated infections caused by Klebsiella pneumoniae isolates are increasing and few effective antibiotics are currently available to treat patients. We observed decreased carbapenem susceptibility among K. pneumoniae isolated from patients at a tertiary private hospital that showed a phenotype compatible with carbapenemase production although this group of enzymes was not detected in any sample. the aim of this study was to describe the epidemiology and clinical outcomes associated with carbapenem-resistant K. pneumoniae and to determine the antimicrobial resistance mechanisms.Methods: Risk factors associated with carbapenem-resistant K. pneumoniae infections were investigated by a matched case-control study from January 2006 through August 2008. A cohort study was also performed to evaluate the association between carbapenem resistance and in-hospital mortality. Bacterial identification and antimicrobial susceptibility were determined by Vitek 2 and Etest. Carbapenemase activity was detected using spectrophotometric assays. Production of beta-lactamases and alterations in genes encoding K. pneumoniae outer membrane proteins, OmpK35 and OmpK36, were analyzed by PCR and DNA sequencing, as well as SDS-Page. Genetic relatedness of carbapenem resistant isolates was evaluated by Pulsed Field Gel Electrophoresis.Results: Sixty patients were included (20 cases and 40 controls) in the study. Mortality was higher for patients with carbapenem-resistant K. pneumoniae infections compared with those with carbapenem-susceptible K. pneumoniae (50.0% vs 25.7%). the length of central venous catheter use was independently associated with carbapenem resistance in the multivariable analysis. All strains, except one, carried bla(CTX-M-2), an extended-spectrum betalactamase gene. in addition, a single isolate also possessed bla(GES-1). Genes encoding plasmid-mediated AmpC beta-lactamases or carbapenemases (KPC, metallo-betalactamases or OXA-carbapenemases) were not detected.Conclusions: the K. pneumoniae multidrug-resistant organisms were associated with significant mortality. the mechanisms associated with decreased K. pneumoniae carbapenem susceptibility were likely due to the presence of cephalosporinases coupled with porin alterations, which resulted from the presence of the insertion sequences in the outer membrane encoding genes.Instituto Israelita de Ensino e Pesquisa Israelita Albert EinsteinHosp Israelita Albert Einstein, Infect Control Unit, BR-05652000 São Paulo, BrazilHosp Israelita Albert Einstein, Microbiol Lab, BR-05651901 São Paulo, BrazilUniversidade Federal de São Paulo UNIFESP EPM, Div Infect Dis, BR-04024002 São Paulo, BrazilHosp Israelita Albert Einstein, Intens Care Unit, BR-05651901 São Paulo, BrazilUniversidade Federal de São Paulo UNIFESP EPM, Div Infect Dis, BR-04024002 São Paulo, BrazilInstituto Israelita de Ensino e Pesquisa Israelita Albert Einstein: 449.08Web of Scienc

Correlation between mass and volume of collected blood with positivity of blood cultures

Background The collection of blood cultures is an extremely important method in the management of patients with suspected infection. Microbiology laboratories should monitor blood culture collection. Methods Over an 8-month period we developed a prospective, observational study in an adult Intensive Care Unit (ICU). We correlated the mass contained in the blood vials with blood culture positivity and we also verified the relationship between the mass of blood and blood volume collected for the diagnosis of bloodstream infection (BSI), as well as we explored factors predicting positive blood cultures. Results We evaluated 345 patients with sepsis, severe sepsis or septic shock for whom blood culture bottles were collected for the diagnosis of BSI. Of the 55 patients with BSI, 40.0 % had peripheral blood culture collection only. BSIs were classified as nosocomial in 34.5 %. In the multivariate model, the blood culture mass (in grams) remained a significant predictor of positivity, with an odds ratio 1.01 (i.e., for each additional 1 mL of blood collected there was a 1 % increase in positivity; 95 % CI 1.01–1.02, p = 0.001; Nagelkerke R Square [R2] = 0.192). For blood volume collected, the adjusted odds ratio was estimated at 1.02 (95 % CI: 1.01–1.03, p \u3c 0.001; R2 = 0.199). For each set of collected blood cultures beyond one set, the adjusted odds ratio was estimated to be 1.27 (95 % CI: 1.14–1.41, p \u3c 0.001; R2 = 0.221). Conclusions Our study was a quality improvement project that showed that microbiology laboratories can use the weight of blood culture bottles to determine if appropriate volume has been collected to improve the diagnosis of BSI

A hospital-based matched case–control study to identify clinical outcome and risk factors associated with carbapenem-resistant <it>Klebsiella pneumoniae</it> infection

Abstract Background Healthcare-associated infections caused by Klebsiella pneumoniae isolates are increasing and few effective antibiotics are currently available to treat patients. We observed decreased carbapenem susceptibility among K. pneumoniae isolated from patients at a tertiary private hospital that showed a phenotype compatible with carbapenemase production although this group of enzymes was not detected in any sample. The aim of this study was to describe the epidemiology and clinical outcomes associated with carbapenem-resistant K. pneumoniae and to determine the antimicrobial resistance mechanisms. Methods Risk factors associated with carbapenem-resistant K. pneumoniae infections were investigated by a matched case–control study from January 2006 through August 2008. A cohort study was also performed to evaluate the association between carbapenem resistance and in-hospital mortality. Bacterial identification and antimicrobial susceptibility were determined by Vitek 2 and Etest. Carbapenemase activity was detected using spectrophotometric assays. Production of beta-lactamases and alterations in genes encoding K. pneumoniae outer membrane proteins, OmpK35 and OmpK36, were analyzed by PCR and DNA sequencing, as well as SDS-Page. Genetic relatedness of carbapenem resistant isolates was evaluated by Pulsed Field Gel Electrophoresis. Results Sixty patients were included (20 cases and 40 controls) in the study. Mortality was higher for patients with carbapenem-resistant K. pneumoniae infections compared with those with carbapenem-susceptible K. pneumoniae (50.0% vs 25.7%). The length of central venous catheter use was independently associated with carbapenem resistance in the multivariable analysis. All strains, except one, carried blaCTX-M-2, an extended-spectrum betalactamase gene. In addition, a single isolate also possessed blaGES-1. Genes encoding plasmid-mediated AmpC beta-lactamases or carbapenemases (KPC, metallo-betalactamases or OXA-carbapenemases) were not detected. Conclusions The K. pneumoniae multidrug-resistant organisms were associated with significant mortality. The mechanisms associated with decreased K. pneumoniae carbapenem susceptibility were likely due to the presence of cephalosporinases coupled with porin alterations, which resulted from the presence of the insertion sequences in the outer membrane encoding genes.</p

Evaluation of Two Methods for Determination of CD64 as a Diagnostic Marker of Infection in Critically Ill Adults

Objectives. Diagnostic markers of infection have had little innovation over the last few decades. CD64, a marker expressed on the surface of neutrophils, may have utility for this purpose. Methods. This study was conducted in an adult intensive care unit (ICU) in São Paulo, Brazil, with 89 patients. We evaluated CD64 in patients with documented or clinically diagnosed infection (infection group) and controls (patients without any evidence of infection) by two different methodologies: method #1, an in house assay, and method #2, the commercial kit Leuko64 (Trillium Diagnostics). Results. CD64 displayed good discriminating power with a 91.2% sensitivity (95% CI 90.7–91.6%) for detecting infection. The commercial kit (Leuko64) demonstrated higher specificity (87.3%) compared with method #1 as well as better accuracy (88.8%). Conclusions. CD64 seems to be a promising marker of infection in the intensive care setting, with Leuko64 showing a slight advantage

Measuring hand hygiene compliance rates in different special care settings: a comparative study of methodologies

Objectives: The purpose of this study was to compare methods for assessing compliance with hand hygiene in an intensive care unit (ICU), a step-down unit (SDU), and a hematology–oncology unit. Methods: Over a 20-week period, we compared hand hygiene compliance measurements by three different methods: direct observation, electronic handwash counter for alcohol gel, and measuring the volume of product used (alcohol gel) in an ICU, an SDU, and a hematology–oncology unit of a tertiary care, private hospital. Results: By direct observation we evaluated 1078 opportunities in the ICU, 1075 in the SDU, and 517 in the hematology–oncology unit, with compliance rates of 70.7%, 75.4%, and 73.3%, respectively. A total of 342 299, 235 914, and 248 698 hand hygiene episodes were recorded by the electronic devices in the ICU, SDU, and hematology–oncology unit, respectively. There were also 127.2 ml, 85.3 ml, and 67.6 ml of alcohol gel used per patient-day in these units. We could find no correlation between the three methods. Conclusions: Hand hygiene compliance was reasonably high in these units, as measured by direct observation. However, a lack of correlation with results obtained by other methodologies brings into question the validity of direct observation results, and suggests that periodic audits using other methods may be needed