Risk Factors for and Clinical Outcomes of Bloodstream Infections Caused by Extended-Spectrum Beta-Lactamase-ProducingKlebsiella pneumoniae

Characteristics of Extended-Spectrum β-Lactamase-Producing Escherichia coli Derived from Food and Humans in Northern Xinjiang, China

This study aimed to investigate the drug resistance, molecular characteristics, and genetic relationship of extended-spectrum β-lactamase (ESBL)-producing Escherichia coli isolated from food and human stool samples in northern Xinjiang. From 2015 to 2016, a total of 431 samples (meats and vegetables) were collected from retail markets and supermarkets located in the regions of Urumqi, Shihezi, and Kuitun in Xinjiang, China, and 20 human stool samples from the Shihezi Hospital. The PCR method was used to detect E. coli, and the presence of ESBL-producing E. coli was confirmed using the K-B disk diffusion confirmatory method. The susceptibility to ESBL-producing E. coli was tested by the microdilution broth method, and the minimum inhibitory concentration was determined. PCR was used to detect the resistance and virulence genes of ESBL-producing E. coli, and phylogenetics, plasmid replicon typing, screening of three integrons, and multilocus sequence typing (MLST) were performed. The results showed that 127 E. coli strains (15 human stool and 112 food samples) were isolated. Out of the 127 E. coli strains, 38 strains (6 human stool and 32 food 34 samples) of ESBL-producing E. coli were identified through screening. These 38 strains showed resistance to cefotaxime (94.74%) and cefepime (94.74%), and were sensitive to meropenem (0.00%). The most detected resistance genes were blaTEM (47.37%), and the most detected virulence genes were fimH (97.73%), ompA (97.73%), hlyE (97.73%), and crl (97.37%). The isolates belonged to phylogroups B1 (42.11%), C (23.68%), and A (21.05%). Among the plasmid replicon subtypes, IncFIB was the main type (42.11%). The integrons detected were of the first type (47.37%) and the third type (26.32%). The 38 E. coli strains had 19 different sequence-type (ST) strains. These 38 strains of ESBL-producing E. coli were analyzed using MLST and STs are varied.

Factors Associated with Extended-spectrum β-lactamase-producing Enterobacteria Isolated from Respiratory Samples

Objective Although extended-spectrum β-lactamase (ESBL)-producing bacteria are a global threat, as they may cause respiratory infection, the factors associated with the isolation of these bacteria from sputum remain unclear. We therefore explored the factors related to ESBL-producing Klebsiella pneumoniae and Escherichia coli isolated from sputum samples. Patients and Methods This study included consecutive patients admitted to our department from 2010 to 2021 with K. pneumoniae or E. coli isolated from their sputum. The patients were categorized into ESBL-producing and non-ESBL-producing groups, and the factors associated with ESBL-producing bacteria isolation were assessed using a binomial logistic regression analysis. Results We included 82 patients, and ESBL-producing pathogens were isolated from 23 (28%). The usage rates of cephem [odds ratio (OR) 4.000, 95% confidence interval (CI) 1.402-11.409, p=0.010], quinolone (OR 2.961, 95% CI 1.097-7.996, p=0.032), and macrolide (OR 4.273, 95% CI 1.518-12.028, p=0.006) in the past year were significantly higher in the ESBL-producing group than in the non-ESBL-producing group. The multivariate analysis revealed that the applications of cephem (adjusted OR: 4.130, 95% CI: 1.233-13.830, p=0.021) and macrolide (adjusted OR: 6.365, 95% CI: 1.922-21.077, p=0.002) was independently associated with the isolation of ESBL-producing bacteria. Conclusions A history of cephem and macrolide use can be considered a risk factor for ESBL-producing bacteria isolation from sputum samples. Physicians need to consider these risk factors when determining antibiotics for the treatment of patients with respiratory infections.

Recent molecules in the treatment of severe infections caused by ESBL-producing bacteria

Introduction: The widespread increase in resistance to β-lactam antibiotics in Enterobacterales currently represents one of the main threats to human health worldwide. The primary mechanisms of resistance are the production of β-lactamase enzymes that are able to hydrolyze β-lactams.Areas covered: we summarize the most recent advances regarding the main characteristics and spectrum of activity of new available antibiotics and strategies for the treatment of ESBL-producing Enterobacterales infections.Expert opinion: ESBL-producing strains are recognized as a worldwide challenge in the treatment of both hospital- and community-acquired infections. Data from the literature point out the high mortality associated with severe infections due to ESBL strains, especially in patients who developed severe sepsis or septic shock, together with the importance of the source of infection and indicators of severity, as determinants of the patient's outcome. Carbapenems are currently considered the first-line therapy, although the diffusion of resistant strains is an evolving problem and is mandatory the introduction in clinical practice of new drug regimens and treatment strategies, based on clinical data, local epidemiology, and microbiology. As a possible carbapenem-sparing strategy, ceftolozane-tazobactam and ceftazidime-avibactam appear the best-available carbapenem-sparing therapies. The definitive role of new drugs should be definitively assessed.

Variation of effect estimates in the analysis of mortality and length of hospital stay in patients with infections caused by bacteria-producing extended-spectrum beta-lactamases: a systematic review and meta-analysis

OBJECTIVE

To assess the variation of effect estimates in the analysis of mortality and length of stay (LOS) in patients with infections caused by extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae.

DESIGN

Systematic review and meta-analysis METHODS: Literature search for clinical studies from 1 January 1960 to 1 October 2018 was conducted in PubMed. Primary outcomes were risk ratios (RRs) of all-cause and attributable mortality and weighted mean differences (WMDs) in LOS in patients with bloodstream infections (BSIs) and non-invasive infections. Any change in the effect estimates was assessed by grouping studies according to design, setting, economy-based country classification, reporting period, microbiological aetiology, infection type and adjustment for appropriateness of empirical treatment. The impact of ESBL production was calculated using random-effect meta-analysis and heterogeneity was evaluated by I² statistics and metaregression.

RESULTS

Eighty-four studies including 22 030 patients and 149 outcome measures were included in the meta-analysis. Most studies were retrospective cohorts from high-income countries, providing unadjusted estimates. ESBL production in patients with BSIs (56 studies) increased the RR for all-cause mortality by a factor of 1.70 (95% CI 1.52 to 1.90; p<0.001), attributable mortality (16 studies) by 1.75 (95% CI 1.448 to 2.108; p<0.001) and WMD in the intensive care unit by 3.07 days (95% CI 1.61 to 4.54; p<0.001). WMD in hospital LOS was significantly higher in BSIs (4.41 days; 95% CI 3.37 to 5.46; p<0.001) and non-invasive (2.19 days; 95% CI 1.56 to 2.81; p<0.001). Subgroup analyses showed variation of estimates by study design, population, strain and assessment of appropriateness of empiric treatment. High heterogeneity was observed in all analyses.

CONCLUSIONS

Current evidence of the clinical burden of infections caused by ESBL-producing bacteria is highly heterogeneous and based mainly on unadjusted estimates derived from retrospective studies. Despite these limitations, ESBL production in strains causing BSIs seems associated with higher all-cause and attributable mortality and longer hospitalisation.

Exploring the phenotype and genotype of multi-drug resistant Klebsiella pneumoniae harbouring blaCTX-M group extended-spectrum β-lactamases recovered from paediatric clinical cases in Shenzhen, China

Background

Emergence and spread of β-lactamase resistant Klebsiella pneumoniae have posed a serious threat, especially in paediatric patients globally. The present study focuses on explore drug resistance profile and molecular characterization of carbapenemase and extended-spectrum β-lactamase producing K. pneumoniae isolated from paediatric patients in Shenzhen, China.

Methods

Present study, a total of 31 isolates of multi-drug resistant K. pneumoniae were collected from Shenzhen Children’s Hospital, China during Jan 2014 to December 2015. ESBLs production was confirmed by using the combination disc diffusion method followed by antimicrobial susceptibility. In addition, β-lactamase encoding genes were determined by PCR assay and sequencing. The genotypic diversity and phylogenetic relationship were determined by multi-locus sequence typing (MLST) method and pulsed-field gel electrophoresis (PFGE).

Results

We examined 31, unique K. pneumoniae isolates collected from 2014 and 2015 in Shenzhen Children’s Hospital, China. All the 31 isolates 100% were resistant to ceftazidime, ertapenem, ampicillin, cefazolin and ampicillin-sulbactam followed by ceftriaxone 94% (n = 29), aztreonam 89% (n = 26), cefepime 84% (n = 26), nitrofurantoin 75% (n = 24), piperacillin 52% (n = 16), and levofloxacin 49% (n = 15). Of the 31 β-lactamase gene coding isolates, bla_CTX-M was mainly detected in about 100% (n = 31), followed by bla_KPC 71% (n = 22), bla_SHV 61% (n = 19), bla_NDM 25% (n = 8), bla_CYM 13% (n = 4), bla_OXA-48 9% (n = 3), bla_GES 9% (n = 3) and bla_TEM 6% (n = 2). Seventeen distinct sequences type were observed with ST20 being mostly identified 16% (n = 5). Pulsed-field gel electrophoresis (PFGE) typing showed that identical profile for the isolates recovered from the Department of Intensive Care Unit and Department of Neurology of our hospital. Plasmid replicon typing result indicates the presence of IncFIS type as highest in all isolates as 61% (n = 19), followed by IncFIB 23% (n = 7), IncFIA and IncFIC 16% (n = 5) each.

Conclusion

Our study reports the occurrence and spread of extended β-lactamase K. pneumoniae ST20 and ST2407 for the first time, in Shenzhen, particularly in paediatric patients. To prevent and control the infection by limiting the spread of infection-causing organisms it is very crucial to detect the presence of resistant genes at an early stage.

Estimating the association between antibiotic exposure and colonization with extended-spectrum β-lactamase-producing Gram-negative bacteria using machine learning methods: a multicentre, prospective cohort study

OBJECTIVES

The aim of the study was to measure the impact of antibiotic exposure on the acquisition of colonization with extended-spectrum β-lactamase-producing Gram-negative bacteria (ESBL-GNB) accounting for individual- and group-level confounding using machine-learning methods.

METHODS

Patients hospitalized between September 2010 and June 2013 at six medical and six surgical wards in Italy, Serbia and Romania were screened for ESBL-GNB at hospital admission, discharge, antibiotic start, and after 3, 7, 15 and 30 days. Primary outcomes were the incidence rate and predictive factors of new ESBL-GNB colonization. Random forest algorithm was used to rank antibiotics according to the risk of selection of ESBL-GNB colonization in patients not colonized before starting antibiotics.

RESULTS

We screened 10 034 patients collecting 28 322 rectal swab samples. New ESBL-GNB colonization incidence with and without antibiotic treatment was 22/1000 and 9/1000 exposure-days, respectively. In the adjusted regression analyses, antibiotic exposure (hazard ratio (HR) 2.38; 95% CI 1.29-4.40), age 60-69 years (HR 1.19; 95% CI 1.05-1.34), and spring season (HR 1.25; 95% CI 1.14-1.38) were independently associated with new colonization. Monotherapy ranked higher als combination therapy in promoting ESBL-GNB colonization. Among monotherapy, cephalosporins ranked first followed by tetracycline (second), macrolide (fourth) and cotrimoxazole (seventh). Overall the ranking of cephalosporins was lower when used in combination. Among combinations not including cephalosporins, quinolones plus carbapenems ranked highest (eighth). Among sequential therapies, quinolones ranked highest (tenth) when prescribed within 30 days of therapy with cephalosporins.

CONCLUSIONS

Impact of antibiotics on selecting ESBL-GNB at intestinal level varies if used in monotherapy or combination and according to previous antibiotic exposure. These finding should be explored in future clinical trials on antibiotic stewardship interventions.

CLINICAL TRIAL REGISTRATION

NCT01208519.

Inappropriate empirical antibiotic therapy does not adversely affect the clinical outcomes of patients with acute pyelonephritis caused by extended-spectrum β-lactamase-producing Enterobacteriales

Extended-spectrum β-lactamase-producing Enterobacteriales (ESBL-PE) are often associated with inappropriate empirical therapy (IAT). The aim of this study was to investigate whether IAT of acute pyelonephritis (APN) caused by ESBL-PE is related to adverse outcomes. A retrospective cohort study was performed at a tertiary-care hospital from 2014 through 2016. Patients who had APN caused by ESBL-PE and were definitely treated with appropriate antibiotics for at least 7 days were enrolled. IAT was defined as when inappropriate empirical antibiotics were given 48 h or longer after initial diagnosis of APN. Primary endpoint was treatment failure defined as clinical and/or microbiologic failure. Secondary endpoints were length of hospital stay and recurrence of APN. Propensity score matching was used to adjust heterogeneity of each group. Among 175 eligible cases, 59 patients received IAT and 116 patients received appropriate empirical antimicrobial therapy (AT). Treatment failure was observed in five (8.4%) patients and nine (7.8%) patients in each group, respectively. After matching, the treatment failure rate was similar between both groups (adjusted odd ratio [aOR] 1.05; 95% confidence index [CI] 0.26-4.15). The length of hospital stay (median 11 days in the IAT group versus 11 days in the AT group; P = 0.717) and absence of recurrence within 2 months (90.3% in IAT and 86.7% in AT; P = 0.642) were also similar. IAT did not adversely affect the clinical outcome. In this regard, clinicians should be more cautious about indiscriminate prescription of broad-spectrum antibiotics such as carbapenem empirically for treatment of APN possibly caused by ESBL-PE.

Extended-spectrum β-lactamase-producing E. coli septicemia among rectal carriers in the ICU

The aim of this study was to identify risk factors for extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (E coli) bloodstream infection (BSI) among carriers hospitalized between March 2011 and June 2016 at the ICU of the West China Hospital.The cases were patients with at least 1 episode of ESBL-producing E coli BSI within 1 week after a positive rectal swab. Controls were selected randomly 1:2 among ESBL-producing E coli rectal carriers who did not develop BSI.Among 19,429 ICU patients, 9015 (46.4%) had a positive rectal swab for ESBL-producing E coli. Of them, 42 (0.5%) were diagnosed with ESBL-producing E coli BSI. The in-hospital mortality was higher for the BSI patients compared with controls (19.1% vs. 6.0%, P = .031). In the past 72 hours, patients in case group were more likely to use penicillin (odds ratio [OR] = 12.076; 95% confidence interval [CI]: 1.397-104.251, P = .02), cephalosporin (OR = 6.900; 95% CI: 1.493-31.852, P = .01), and carbapenem (OR = 5.422; 95% CI: 1.228-23.907, P = .03) as compared to patients in control group. Also, when compared to patients in control group, patients in case group were likely to stay for a longer time in ICU before positive rectal swab test (OR = 1.041, 95% CI: 1.009-1.075, P = .01) and have higher maximum body temperature before positive rectal swab (OR = 8.014; 95% CI: 2.408-26.620, P = .001).Bacteremia owing to ESBL-producing E coli was associated with high antimicrobial exposure, hospital stay, and maximum body temperature.

Temporal association between antibiotic use and resistance in Klebsiella pneumoniae at a tertiary care hospital

Background

β-Lactam/β-lactamase inhibitors (BLBLIs) were introduced into clinical practice as an alternative to carbapenems for treating multi-drug-resistant Klebsiella pneumoniae infections. However, little is known about the relationship between BLBLI treatment and antimicrobial resistance. In this study, we investigated the trends and the temporal association between antibiotic use and antimicrobial resistance in K. pneumoniae isolates obtained between 2012 and 2016.

Methods

Data regarding quarterly consumption (total number of prescriptions per quarter) of all BLBLIs, all third-generation cephalosporins, and all fluoroquinolones at a tertiary care hospital were obtained from the Korean Health Insurance Review and Assessment Service. Susceptibility data (isolation rate of antibiotic resistance per quarter) were obtained from the existing database of the same tertiary hospital. Regression analysis was used to analyze annual trends and cross-correlations to assess the temporal association on a quarterly basis between antibiotic consumption and antibiotic resistance in K. pneumoniae.

Results

The rate of resistance to piperacillin/tazobactam in K. pneumoniae significantly increased over the study period (p < 0.01). The consumption of all BLBLIs was also found to be significantly correlated with the rate of resistance to piperacillin/tazobactam (β = 0.66; p < 0.01), ceftazidime (β = 0.54; p = 0.02), and levofloxacin (β = - 0.60; p = 0.01) with two-quarter lags. Furthermore, the consumption of all third-generation cephalosporins was significantly correlated with rates of K. pneumoniae resistance to ceftazidime (β = 0.64; p < 0.01) with a two-quarter lag and levofloxacin (β = 0.50; p = 0.03) with a quarter lag. The consumption of all fluoroquinolones correlated with resistance rates to ceftazidime (β = 0.14; p < 0.01) with a two-quarter lag.

Conclusions

The rate of resistance to piperacillin/tazobactam in K. pneumoniae increased significantly over the study period and was significantly correlated with BLBLI consumption. While BLBLIs can potentially be utilized as an alternative to carbapenems, our findings reinforce concerns of resistance to these drugs. Further research is needed to understand the implications on resistance of utilizing BLBLIs as a carbapenem-sparing option.

Predictors of outcome in patients with severe sepsis or septic shock due to extended-spectrum β-lactamase-producing Enterobacteriaceae

PURPOSE

There are few data in the literature regarding sepsis or septic shock due to extended-spectrum β-lactamases (ESBL)-producing Enterobacteriaceae (E). The aim of this study was to assess predictors of outcome in septic patients with bloodstream infection (BSI) caused by ESBL-E.

METHODS

Patients with severe sepsis or septic shock and BSI due to ESBL-E were selected from the INCREMENT database. The primary endpoint of the study was the evaluation of predictors of outcome after 30 days from development of severe sepsis or septic shock due to ESBL-E infection. Three cohorts were created for analysis: global, empirical-therapy and targeted-therapy cohorts.

RESULTS

367 septic patients were analysed. Overall mortality was 43.9% at 30 days. Escherichia coli (62.4%) and Klebsiella pneumoniae (27.2%) were the most frequent isolates. β-lactam/β-lactamase inhibitor (BLBLI) combinations were the most empirically used drug (43.6%), followed by carbapenems (29.4%). Empirical therapy was active in vitro in 249 (67.8%) patients, and escalation of antibiotic therapy was reported in 287 (78.2%) patients. Cox regression analysis showed that age, Charlson Comorbidity Index, McCabe classification, Pitt bacteremia score, abdominal source of infection and escalation of antibiotic therapy were independently associated with 30-day mortality. No differences in survival were reported in patients treated with BLBLI combinations or carbapenems in empirical or definitive therapy.

CONCLUSIONS

BSI due to ESBL-E in patients who developed severe sepsis or septic shock was associated with high 30-day mortality. Comorbidities, severity scores, source of infection and antibiotic therapy escalation were important determinants of unfavorable outcome.

Clinical outcomes of elderly patients with bloodstream infections due to extended-spectrum β-lactamase-producing Enterobacteriaceae in an Italian Internal Medicine ward

PURPOSE

Infections caused by ESBL-producing Enterobacteriaceae (ESBL-EB) are a major health problem, but data regarding elderly patients is lacking.

METHODS

We performed a retrospective observational study quantifying the effects of antimicrobial treatment and primary infection site on clinical outcomes in an historical case series of 42 patients aged 80.7±10years admitted to an Internal Medicine ward in Italy for ESBL-EB bloodstream infections (BSI).

RESULTS

At multivariate risk analysis, we found that urinary tract as primary infection site (RR=0.181 [0.037-0.886], p=0.035) and definitive antibiotic therapy (RR=0.517 [0.147-0.799], p=0.038) decreased the relative risk of a negative clinical response, while the respiratory tract origin increased the relative risk (RR=2.788 [1.407-9.228], p=0.025). Also regarding 30days mortality, multivariate risk analysis identified that urinary tract as primary infection site (RR=0.098 [0.011-0.743], p=0.025) and definitive antibiotic therapy (RR=0.236 [0.058-0.961], p=0.044) decreased the relative risk, while the respiratory origin increased the relative risk (RR=4.241 [1.040-17.295], p=0.014). We observed similar outcomes in patients definitively treated with carbapenems or with carbapenem-free treatments. Additionally, an initially inappropriate therapy did not correlate with worse outcomes if a switch to an effective definitive treatment was performed promptly.

CONCLUSIONS

Carbapenem-sparing regimens (e.g. piperacillin-tazobactam alone or with an aminoglycoside) could be empirically safely used in elderly patients at high risk of ESBL-EB BSI and for definitive treatment of ascertained cases if the primary site is the urinary tract, leaving early carbapenem use for cases at higher risk of death, such as those with pneumonia.

A simple scoring algorithm predicting extended-spectrum β-lactamase producers in adults with community-onset monomicrobial Enterobacteriaceae bacteremia: Matters of frequent emergency department users

The incidence of community-onset bacteremia caused by extended-spectrum-β-lactamase (ESBL) producers is increasing. The adverse effects of ESBL production on patient outcome have been recognized and this antimicrobial resistance has significant implications in the delay of appropriate therapy. However, a simple scoring algorithm that can easily, inexpensively, and accurately be applied to clinical settings was lacking. Thus, we established a predictive scoring algorithm for identifying patients at the risk of ESBL-producer infections among patients with community-onset monomicrobial Enterobacteriaceae bacteremia (CoMEB).In a retrospective cohort, multicenter study, adults with CoMEB in the emergency department (ED) were recruited during January 2008 to December 2013. ESBL producers were determined based on ESBL phenotype. Clinical information was obtained from chart records.Of the total 1141 adults with CoMEB, 65 (5.7%) caused by ESBL producers were identified. Four independent multivariate predictors of ESBL-producer bacteremia with high odds ratios (ORs)-recent antimicrobial use (OR, 15.29), recent invasive procedures (OR, 12.33), nursing home residents (OR, 27.77), and frequent ED user (OR, 9.98)-were each assigned +1 point to obtain the CoMEB-ESBL score. Using the proposed scoring algorithm, a cut-off value of +2 yielded a high sensitivity (84.6%) and an acceptable specificity (92.5%); the area under the receiver operating characteristic curve was 0.92.In conclusion, this simple scoring algorithm can be used to identify CoMEB patients with a high ESBL-producer infection risk. Of note, frequent ED user was firstly demonstrated to be a crucial predictor in predicting ESBL-producer infections. ED clinicians should consider adequate empirical therapy with coverage of these pathogens for patients with risk factors.

Clinical Epidemiology of Ciprofloxacin Resistance and Its Relationship to Broad-Spectrum Cephalosporin Resistance in Bloodstream Infections Caused by Enterobacter Species

Objectives:

To evaluate the clinical features of ciprofloxacin-resistant Enterobacter bacteremia and to examine the risk factors for ciprofloxacin resistance in Enterobacter species isolates causing bacteremia.

Design:

A case-control study.

Setting:

A 1,500-bed, tertiary-care university hospital and referral center.

Patients:

All patients older than 16 years with Enterobacter species isolated from blood were enrolled. The medical records of 183 patients with clinically significant Enterobacter bacteremia from January 1998 to December 2002 were identified. We compared patients with bacteremia caused by ciprofloxacin-susceptible isolates with patients with bacteremia caused by ciprofloxacin-resistant isolates.

Results:

Twenty-three (12.6%) of the patients had bacteremia caused by isolates resistant to ciprofloxacin. There were no significant differences in age, gender, underlying diseases, primary site of infection, or Acute Physiology and Chronic Health Evaluation II score between the ciprofloxacin-resistant and the ciprofloxacin-susceptible groups. Broad-spectrum cephalosporin resistance, defined as resistance to cefotaxime or ceftazidime in vitro, was detected in 21 (91.3%) of 23 ciprofloxacin-resistant isolates compared with 65 (40.6%) of 160 ciprofloxacin-susceptible isolates (P < .001). Multivariate analysis revealed that independent risk factors for ciprofloxacin resistance were the prior receipt of fluoroquinolones (P < .001) and broad-spectrum cephalosporin resistance (P < .001).

Conclusions:

In Enterobacter species isolates causing bacteremia, ciprofloxacin resistance was closely associated with the prior receipt of fluoroquinolones and broad-spectrum cephalosporin resistance. The close relationship between ciprofloxacin resistance and broad-spectrum cephalosporin resistance is particularly troublesome because it severely restricts the therapeutic options for Enterobacter species infection.

Antimicrobial Susceptibility Patterns Among Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae in a Large Pediatric Hospital in the United Kingdom

Of the 551 extended spectrum β-lactamase-producing isolates characterized, the MIC90 for Escherichia coli, Klebsiella spp., and Enterobacter spp. were in the susceptible range when tested against meropenem, but were in the resistant range for all other antimicrobials tested excluding E coli and Klebsiella spp. against ertapenem and ciprofloxacin, and for Enterobacter spp. against ciprofloxacin.

Clinical and Molecular Epidemiology of Extended-Spectrum Beta-Lactamase-Producing Klebsiella spp.: A Systematic Review and Meta-Analyses

Healthcare-related infections caused by extended-spectrum beta-lactamase (ESBL)-producing Klebsiella spp. are of major concern. To control transmission, deep understanding of the transmission mechanisms is needed. This systematic review aimed to identify risk factors and sources, clonal relatedness using molecular techniques, and the most effective control strategies for ESBL-producing Klebsiella spp. A systematic search of PubMed, Embase, and Outbreak Database was performed. We identified 2771 articles from November 25th, 1960 until April 7th, 2014 of which 148 were included in the systematic review and 23 in a random-effects meta-analysis study. The random-effects meta-analyses showed that underlying disease or condition (odds ratio [OR] = 6.25; 95% confidence interval [CI] = 2.85 to 13.66) generated the highest pooled estimate. ESBL-producing Klebsiella spp. were spread through person-to-person contact and via sources in the environment; we identified both monoclonal and polyclonal presence. Multi-faceted interventions are needed to prevent transmission of ESBL-producing Klebsiella spp.

Infection with multidrug-resistant gram-negative bacteria in a pediatric oncology intensive care unit: risk factors and outcomes

OBJECTIVE

This study aimed at evaluating the predictors and outcomes associated with multidrug-resistant gram-negative bacterial (MDR-GNB) infections in an oncology pediatric intensive care unit (PICU).

METHODS

Data were collected relating to all episodes of GNB infection that occurred in a PICU between January of 2009 and December of 2012. GNB infections were divided into two groups for comparison: (1) infections attributed to MDR-GNB and (2) infections attributed to non-MDR-GNB. Variables of interest included age, gender, presence of solid tumor or hematologic disease, cancer status, central venous catheter use, previous Pseudomonas aeruginosa infection, healthcare-associated infection, neutropenia in the preceding 7 days, duration of neutropenia, length of hospital stay before ICU admission, length of ICU stay, and the use of any of the following in the previous 30 days: antimicrobial agents, corticosteroids, chemotherapy, or radiation therapy. Other variables included initial appropriate antimicrobial treatment, definitive inadequate antimicrobial treatment, duration of appropriate antibiotic use, time to initiate adequate antibiotic therapy, and the 7- and 30-day mortality.

RESULTS

Multivariate logistic regression analyses showed significant relationships between MDR-GNB and hematologic diseases (odds ratio [OR] 5.262; 95% confidence interval [95% CI] 1.282-21.594; p=0.021) and healthcare-associated infection (OR 18.360; 95% CI 1.778-189.560; p=0.015). There were significant differences between MDR-GNB and non-MDR-GNB patients for the following variables: inadequate initial empirical antibiotic therapy, time to initiate adequate antibiotic treatment, and inappropriate antibiotic therapy.

CONCLUSIONS

Hematologic malignancy and healthcare-associated infection were significantly associated with MDR-GNB infection in this sample of pediatric oncology patients.

Re-engineering nalidixic acid's chemical scaffold: A step towards the development of novel anti-tubercular and anti-bacterial leads for resistant pathogens

Occurrence of antibacterial and antimycobacterial resistance stimulated a thrust to discover new drugs for infectious diseases. Herein we report the work on re-engineering nalidixic acid's chemical scaffold for newer leads. Stepwise clubbing of quinoxaline, 1,2,4-triazole/1,3,4-oxadiazole with nalidixic acid yielded better compounds. Compounds were screened against ciprofloxacin resistant bacteria and Mycobacterium tuberculosis H37Rv species. Results were obtained as minimum inhibitory concentration, it was evident that molecule with quinoxaline linked azide as side chain served as antitubercular lead (<6.25 μg/ml) whilst molecule with oxadiazole or triazole linked quinoxaline side chain served as anti-bacterial lead. Few compounds were significantly active against Escherichia coli and Proteus vulgaris with MIC less than 0.06 μg/ml and relatively potent than ciprofloxacin. No true compound was potentially active against Salmonella species as compared to amoxicillin.

Risk factors for bloodstream infection caused by extended-spectrum β-lactamase-producing Escherichia coli and Klebsiella pneumoniae: A focus on antimicrobials including cefepime

BACKGROUND

Extended-spectrum β-lactamase (ESBL)-producing pathogens represent increasing challenges to physicians because of rising prevalence, high mortality, and challenging treatment. Identifying high risks and early appropriate therapy is critical to favorable outcomes.

METHODS

This is a 5-year retrospective case-case-control study performed at the Detroit Medical Center on adult patients with bloodstream infection (BSI) caused by ESBL-producing and non-ESBL-producing Escherichia coli or Klebsiella pneumoniae, each compared with uninfected controls. Data were collected from December 2004-August 2009. Multivariate analysis was performed using logistic regression.

RESULTS

Participants included 103 patients with BSI caused by ESBL-producing pathogens and 79 patients with BSI caused by pathogens that did not produce ESBLs. The mean age of patients in the ESBL group was 67 years; of the patients, 51% were men, 77% were black, and 38% (n = 39) died in hospital. The mean age of patients in the non-ESBL group was 58 years; of the patients, 51% were men, 92% were black, and 22% (n = 17) died in hospital. On multivariate analysis, predictors of BSI caused by ESBL-producing pathogens included central venous catheter (odds ratio [OR], 29.4; 95% confidence interval [CI], 3.0-288.3), prior β-lactam-/β-lactamase-inhibitor therapy (OR, 28.1; 95% CI, 1.99-396.5), and prior cefepime therapy (OR, 22.7; 95% CI, 2.7-192.4). The only risk factor for BSI caused by non-ESBL-producing pathogens was urinary catheter insertion (OR, 18.2; 95% CI, 3.3-100.3).

CONCLUSION

Prior antimicrobial therapy, particularly with β-lactam, was the strongest unique risk factor for BSI caused by ESBL-producing E coli or K pneumoniae.

Risk Factors for and Outcomes of Bacteremia Caused by Extended-Spectrum ß-Lactamase-Producing Escherichia coli and Klebsiella Species at a Canadian Tertiary Care Hospital

BACKGROUND

Antimicrobial resistance due to production of extended-spectrum ß-lactamases by Escherichia coli and Klebsiella species (ESBL-EK) is concerning. Previous studies have shown that bacteremia due to ESBL-producing organisms is associated with increases in length of stay and/or mortality rate. Rates of infection by ESBL-EK vary worldwide, and regional differences in the prevalence of risk factors are likely. Few Canadian studies assessing risk factors for ESBL-EK infections or the outcomes of empiric therapy have been published.

OBJECTIVES

To determine risk factors for and patient outcomes associated with ESBL-EK bacteremia. The appropriateness of empiric antibiotic therapy and the effect of inappropriate empiric therapy on these outcomes were also examined.

METHODS

In a retrospective, 1:1 case-control study conducted in a tertiary care hospital between 2005 and 2010, data for 40 patients with ESBL-EK bacteremia were compared with data for 40 patients who had non-ESBL-EK bacteremia.

RESULTS

Of all variables tested, only antibiotic use within the previous 3 months was found to be an independent risk factor for acquisition of ESBL-EK bacteremia (odds ratio 5.2, 95% confidence interval 1.6-16.9). A greater proportion of patients with non-ESBL-EK bacteremia received appropriate empiric therapy (88% [35/40] versus 15% [6/40], p < 0.001). Time to appropriate therapy was longer for those with ESBL-EK bacteremia (2.42 days versus 0.17 day, p < 0.001). Patient outcomes, including length of stay in hospital, admission to the intensive care unit (ICU), length of stay in the ICU (if applicable), and in-hospital mortality were not affected by the presence of ESBL-EK or the appropriateness of empiric therapy.

CONCLUSIONS

Previous antibiotic use was a significant, independent risk factor for acquiring ESBL-EK. Thus, prior antibiotic use is an important consideration in the selection of empiric antibiotic therapy and should increase the concern for resistant pathogens.

Characteristics and outcomes of Klebsiella pneumoniae bacteraemia in Hong Kong

BACKGROUND

We compared clinical outcomes between patients with healthcare-associated and community-acquired Klebsiella pneumoniae bacteraemia and identified predictors associated with mortality and high treatment cost in Hong Kong.

METHODS

This was a retrospective cohort study of patients with K. pneumoniae bacteraemia in a teaching hospital. Adult patients with K. pneumoniae in blood cultures were included. Demographics and clinical data were retrieved from medical records.

RESULTS

The analysis included 208 patients. The mean age was 68.6 ± 16.8 years. The Pitt bacteraemia score was 2.2 ± 2.8. In all, 54.8% cases were healthcare-associated infections. The 30-day mortality rate was 32.7%. The mortality rate of patients with healthcare-associated bacteraemia was significantly higher than for community-acquired cases (p < 0.001). Extended-spectrum β-lactamase (ESBL)-producing K. pneumoniae accounted for 15.4% of cases. Intra- abdominal infection was the most common infection (32.7%). Prior use of immunosuppressive agents and antimicrobial therapy were two major predisposing factors for infection. The treatment cost was USD12 282 ± 11 751 and the length of hospitalization was 9.0 ± 6.7 days. Multivariate analysis showed that liver disease (odds ratio (OR) = 3.06; 95% confidence interval (CI) = 1.38-6.78), malignancy (OR = 6.86; 95% CI = 3.25-14.48), pneumonia (OR = 5.25; 95% CI = 2.05-13.41) and Pitt score > 1 (OR = 2.50; 95% CI = 1.25-5.00) were associated with mortality. Malignancy (OR = 2.94; 95% CI = 1.33-6.49), Pitt score > 1 (OR = 4.15; 95% CI = 1.87-9.24) and age < 72 years (OR = 2.86; 95% CI = 1.35-5.88) were associated with high treatment cost.

CONCLUSIONS

The 30-day mortality and treatment cost of patients with K. pneumoniae bacteraemia were high in Hong Kong. Based upon the risk factors identified, infection control and treatment algorithms for K. pneumoniae bacteraemia in patients with malignancy or liver disease are highly warranted.

Risk Factors for and Outcomes of Healthcare-Associated Infection Due to Extended-Spectrum β-Lactamase-Producing Escherichia coli or Klebsiella pneumoniae in Thailand

A matched case-control study was performed to evaluate the risk factors for and outcomes of healthcare-associated infection due to extended-spectrum β-lactamase-producing Escherichia coli or extended-spectrum β-lactamase-producing Klebsiella pneumoniae in Thailand. By multivariable analysis, prior exposure to third-generation cephalosporins and transfer from another hospital were risk factors associated with infection. Receipt of inadequate antimicrobial therapy was a predictor of mortality.

Clinical and Molecular Epidemiology of Healthcare-Associated Infections Due to Extended-Spectrumβ-Lactamase (ESBL)–Producing Strains ofEscherichia coliandKlebsiella pneumoniaeThat Harbor Multiple ESBL Genes

Objectives.

To characterize healthcare-associated infections due to extended-spectrumβ-lactamase (ESBL)-producing strains ofEscherichia coliandKlebsiella pneumoniaethat harbor multiple ESBL genes, as opposed to a single ESBL gene.

Methods.

All patients with a confirmed healthcare-associated infection due to an ESBL-producing strain ofE. coliorK. pneumoniaewere enrolled in the study. Molecular typing of isolates was performed, and the comparative risks and outcomes of patients were analyzed.

Results.

Among 71 patients with healthcare-associated infection due to an ESBL-producing strain ofE. coliorK. pneumoniae, the gene for CTX-M, with or without other ESBL genes, was identified in all 51 (100%) of the patients infected with anE. colistrain and in 18 (90%) of the 20 patients infected with aK. pneumoniaestrain. Of these 71 patients, 17 (24%) met the definition of healthcare-associated infection due to an ESBL-producing strain that harbored multiple genes; in multivariate analysis, previous exposure to 3 or more classes of antibiotics (adjusted odds ratio, 4.5 [95% confidence interval, 1.7-75.2]) was the sole risk factor for healthcare-associated infection due to an ESBL-producing strain that harbored multiple ESBL genes. Isolates recovered from patients with healthcare-associated infection due to an ESBL-producing strain that harbored multiple ESBL genes were more resistant to various antibiotic classes, and, compared with patients with healthcare-associated infection due to an ESBL-producing strain that harbored a single ESBL gene, they were more likely to have ineffective initial empirical antimicrobial therapy (52% vs 94%; odds ratio, 5.1 [95% confidence interval, 1.04-14.5]).

Conclusions.

CTX-M ESBL is highly prevalent in Thailand. Patients with healthcare-associated infection due to an ESBL-producing strain that harbored multiple ESBL genes were more likely to have had ineffective initial empirical antimicrobial therapy, and, given that antibiotic selection pressure was the only associated risk, we suggest focused antimicrobial stewardship programs to limit the emergence and spread of healthcare-associated infection due to ESBL-producing strains in this middle-income country.

Klebsiella pneumoniae bloodstream infection: epidemiology and impact of inappropriate empirical therapy

Multidrug resistance associated with extended-spectrum beta-lactamase (ESBL) and Klebsiella pneumoniae carbapenemase (KPC) among K. pneumoniae is endemic in southern Europe. We retrospectively analyzed the impact of resistance on the appropriateness of empirical therapy and treatment outcomes of K. pneumoniae bloodstream infections (BSIs) during a 2-year period at a 1420-bed tertiary-care teaching hospital in northern Italy. We identified 217 unique patient BSIs, including 92 (42%) KPC-positive, 49 (23%) ESBL-positive, and 1 (0.5%) metallo-beta-lactamase-positive isolates. Adequate empirical therapy was administered in 74% of infections caused by non-ESBL non-KPC strains, versus 33% of ESBL and 23% of KPC cases (p < 0.0001). To clarify the impact of resistance on BSI treatment outcomes, we compared several different models comprised of non-antibiotic treatment-related factors predictive of patients' 30-day survival status. Acute Physiology and Chronic Health Evaluation (APACHE) II score determined at the time of positive blood culture was superior to other investigated models, correctly predicting survival status in 83% of the study cohort. In multivariate analysis accounting for APACHE II, receipt of inadequate empirical therapy was associated with nearly a twofold higher rate of death (adjusted hazard ratio 1.9, 95% confidence interval 1.1-3.4; p = 0.02). Multidrug-resistant K. pneumoniae accounted for two-thirds of all K. pneumoniae BSIs, high rates of inappropriate empirical therapy, and twofold higher rates of patient death irrespective of underlying illness.

Effect of ceftriaxone on the outcome of murine pyelonephritis caused by extended-spectrum-β-lactamase-producing Escherichia coli

Urinary tract infections (UTIs) due to extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae in children are becoming more frequent, and they are commonly treated initially with a second- or third-generation cephalosporin. We developed a murine model of ascending UTI caused by ESBL-producing Escherichia coli. Using this model, we investigated the renal bacterial burden, interleukin-6 (IL-6) expression, and histopathological alterations caused by ESBL- and non-ESBL-producing bacteria after 1, 2, or 6 days with or without ceftriaxone therapy. The renal bacterial burden, IL-6 concentration, and histological inflammatory lesions were not significantly different between mice infected with ESBL- and non-ESBL-producing bacteria without treatment at any of the time points examined. Following ceftriaxone administration, the bacterial burden was eliminated in the kidneys of mice infected with ESBL- and non-ESBL-producing bacteria on the 6th postinfection day. The histological analysis demonstrated that among mice treated with ceftriaxone, those infected with ESBL-producing bacteria had more profound renal alterations than those infected with non-ESBL-producing bacteria on the 6th day (P < 0.001). In comparison, microbiological outcomes did not differ significantly between mice infected with ESBL- and non-ESBL-producing bacteria at any of the time points examined. The effectiveness of ceftriaxone in mice with UTIs due to ESBL-producing E. coli may have therapeutic implications; it is, however, hampered by limited activity on the histopathological lesions, a finding that needs further investigation.

Predictors of 7- and 30-day mortality in pediatric intensive care unit patients with cancer and hematologic malignancy infected with Gram-negative bacteria

Background

Infection with Gram-negative bacteria is associated with increased morbidity and mortality. The aim of this study was to evaluate the predictors of 7- and 30-day mortality in pediatric patients in an intensive care unit with cancer and/or hematologic diseases and Gram-negative bacteria infection.

Methods

Data were collected relating to all episodes of Gram-negative bacteria infection that occurred in a pediatric intensive care unit between January 2009 and December 2012, and these cases were divided into two groups: those who were deceased seven and 30 days after the date of a positive culture and those who survived the same time frames. Variables of interest included age, gender, presence of solid tumor or hematologic disease, cancer status, central venous catheter use, previous Pseudomonas aeruginosa infection, infection by multidrug resistant-Gram-negative bacteria, colonization by multidrug resistant-Gram-negative bacteria, neutropenia in the preceding seven days, neutropenia duration ≥3 days, healthcare-associated infection, length of stay before intensive care unit admission, length of intensive care unit stay >3 days, appropriate empirical antimicrobial treatment, definitive inadequate antimicrobial treatment, time to initiate adequate antibiotic therapy, appropriate antibiotic duration ≤3 days, and shock. In addition, use of antimicrobial agents, corticosteroids, chemotherapy, or radiation therapy in the previous 30 days was noted.

Results

Multivariate logistic regression analysis resulted in significant relationship between shock and both 7-day mortality (odds ratio 12.397; 95% confidence interval 1.291–119.016; p = 0.029) and 30-day mortality (odds ratio 6.174; 95% confidence interval 1.760–21.664; p = 0.004), between antibiotic duration ≤3 days and 7-day mortality (odds ratio 21.328; 95% confidence interval 2.834-160.536; p = 0.003), and between colonization by multidrug resistant-Gram-negative bacteria and 30-day mortality (odds ratio 12.002; 95% confidence interval 1.578–91.286; p = 0.016).

Conclusions

Shock was a predictor of 7- and 30-day mortality, and colonization by multidrug resistant-Gram-negative bacteria was an important risk factor for 30-day mortality.

Third-generation cephalosporin resistance of community-onset Escherichia coli and Klebsiella pneumoniae bacteremia in a secondary hospital

BACKGROUND/AIMS

To enable appropriate antimicrobial treatment for community-onset infections in emergency departments (EDs), data are needed on the resistance profiles of Escherichia coli and Klebsiella pneumoniae, which are the main pathogens of community-onset bacteremia.

METHODS

Records were reviewed of 734 patients with E. coli and K. pneumoniae bacteremia who visited the Daegu Fatima Hospital ED, Daegu, Korea between 2003 and 2009. We investigated the demographic data, clinical findings, and antimicrobial susceptibility patterns of the organisms.

RESULTS

Of 1,208 cases of community-onset bacteremia, 62.8% were caused by E. coli or K. pneumoniae in an ED of a secondary care hospital. Five hundred and forty-eight cases of E. coli (75%) and 183 cases of K. pneumoniae (25%) were analyzed. Urinary tract infection (43.1%) was most common, followed by intra-abdominal infection (39%) and pneumonia (7.2%). Trimethoprim/sulfamethoxazole, fluoroquinolone, third-generation cephalosporin (3GC) and amikacin resistance rates among E. coli and K. pneumoniae were 22.8%, 19.6%, 6.2%, and 1.3%, respectively. In 2009, the rate of 3GC resistance (10.6%) was significantly higher, compared to the annual averages of 2003 to 2008 (6.1%; p = 0.03). Previous exposure to antibiotics was an independent risk factor for 3GC resistance in multivariate logistic regression analysis.

CONCLUSIONS

The rate of 3GC resistance increased in community-onset infections, and previous exposure to antibiotics was an independent risk factor. Despite the increased 3GC resistance in community-onset infections, an amikacin combination therapy could provide an option for treatment of bacteremic patients with previous antibiotic exposure in an ED.

Impact of extended-spectrum beta-lactamase on acute pyelonephritis treated with empirical ceftriaxone

BACKGROUND

Ceftriaxone is frequently administered empirically for hospitalized patients with acute pyelonephritis (APN) due to prevalent quinolone resistance in our hospital; however, its use is inappropriate for extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli, an increasing problem.

METHODS

A retrospective, 1:2 matched cohort study was performed to evaluate the impact of ESBL on APN treated with empirical ceftriaxone. Each patient in ESBL group was matched with two patients in the non-ESBL group, using a 16-point scoring system, which included age, sex, bacteremia, simplified acute physiology score 2, Charlson comorbidity index and APN severity score.

RESULTS

From 2009 to 2011, among 1,322 community-onset cases of the E. coli bacteriuria with 212 (16%) ESBL producers, 261 patients with APN were treated empirically with ceftriaxone in a secondary care hospital. Among these 261 cases, twenty-six patients in the ESBL group and 52 matched patients in the non-ESBL group (1:2) were included. Mean time to defervescence was 4.6±2.2 days in the ESBL group and 2.6±1.3 days in the non-ESBL group (p<0.01). Rate of microbiological resolution within 5 days after antibiotic treatment was 77% (17/22) in the ESBL group and 100% (45/45) in the non-ESBL group (p=0.01). The duration of hospitalization was 13.3±8.2 days in the ESBL group and 7.3±3.5 days in the non-ESBL group (p<0.01). No patient died in either group.

CONCLUSION

Empirical ceftriaxone therapy for APN caused by ESBL-producing E. coli is inappropriate, and consequently can delay recovery and result in longer hospitalization.

Can a routine follow-up blood culture be justified in Klebsiella pneumoniae bacteremia? A retrospective case-control study

Background

The need for mandatory confirmation of negative conversion in Klebsiella pneumoniae bacteremia (KpB) has not been adequately addressed. We conducted a retrospective case–control study of adult patients with KpB over a 5-year period in two tertiary-care hospitals to determine the risk factors for persistent bacteremia and to reevaluate the necessity of follow-up blood culture in KpB.

Methods

Persistent KpB is defined as the finding of K. pneumoniae in more than two separate blood-culture samples for longer than a two-day period in a single episode. The case- and control-groups were patients with persistent and non-persistent KpB, respectively, and they were matched 1-to-3 according to age and gender.

Results

Among 1068 KpB episodes analyzed after excluding polymicrobial infection and repeated KpB, follow-up blood cultures were performed in 862 cases (80.7%), 62 of which (7.2%) were persistent. Independent risk factors for persistence were intra-abdominal infection, higher Charlson’s comorbidity weighted index score, prior solid organ transplantation, and unfavorable treatment response, which was defined as positivity for at least two parameters among fever, leukocytosis, and no decrease of C-reactive protein on the second day after initial culture. A proposed scoring system using four variables, namely, intra-abdominal infection, nosocomial KpB, fever and lack of C-reactive protein decrease, the last two being assessed on the second day after the initial blood culture, showed that only 4.9% of the patients with no risk factors or with only intra-abdominal infection had persistent KpB.

Conclusions

Though persistent KpB is uncommon, follow-up blood culture was performed in as many as 80% of the cases in this study. A more careful clinical assessment is warranted to reduce the cost and patient inconvenience involved in follow-up blood culture.

Risk factors for bacteriuria with carbapenem-resistant Klebsiella pneumoniae and its impact on mortality: a case-control study

BACKGROUND

The objective of this study was to evaluate the mortality of and risk factors for bacteriuria due to carbapenem-resistant Klebsiella pneumoniae (CRKp) versus carbapenem-susceptible K. pneumoniae (CSKp) producing extended spectrum β lactamase (ESBL).

METHODS

This was a retrospective case-control study in which 135 case-patients with bacteriuria due to CRKp were compared with 127 control patients with CSKp producing ESBL. In a first step, multivariate Cox regression and Kaplan-Meier survival analysis models were used to determine the difference in mortality between the two groups and risk factors for mortality. In a second step, a univariate analysis was used to identify risk factors for CRKp colonization.

RESULTS

There were no significant demographic or clinical differences between the groups. In-hospital mortality in the study and control groups was 29 and 25 %, respectively (non-significant difference). Multivariate analysis revealed that the most important risk factor for mortality in both groups was being bed ridden [hazard ratio 2.2, 95 % confidence interval (CI) 1.23-3.93; P = 0.008]. Patients with CRKp bacteriuria had a longer hospitalization time with a mean ± standard deviation of 28 ± 33 days compared to 22 ± 28 days in the control group (P < 0.05). Several univariate risk factors for acquiring CRKp bacteriuria were identified: antibiotic use [odds ratio (OR) 1.93, 95 % CI 1.18-3.17, p = 0.008], especially colistin (OR 2.04, 95 % CI 1.04-4.02; P = 0.036), presence of a urinary catheter (OR 2.09, 95 % CI 1.2-3.63; P = 0.008), surgery (OR 3.94, 95 % CI 1.85-8.37; P = 0.0002), invasive procedures (OR 3.06, 95 % CI 1.61-5.8; P = 0.0004), and intensive care unit admission (OR 2.49, 95 % CI 1.18-5.37; P = 0.015).

CONCLUSION

Bacteriuria caused by CRKp as compared that caused by CSKp was not found to be a risk factor for death.

Detecting risk and predicting patient mortality in patients with extended-spectrum β-lactamase-producing Enterobacteriaceae bloodstream infections

Extended-spectrum β-lactamases (ESBLs) have been increasingly described worldwide, especially among Enterobacteriaceae isolates, and recently not only in the nosocomial, but also in the community setting. Bloodstream infections (BSIs) caused by ESBL-producing Enterobacteriaceae have been associated with increased rates of treatment failure, mortality and hospital costs. Any delay in the initiation of adequate antibiotic therapy is potentially lethal for patients with BSIs caused by ESBL-producing Enterobacteriaceae. The awareness of changes in bacterial resistance patterns, the careful knowledge of risk factors for ESBL infection and of factors facilitating adverse outcome, giving attention to local epidemiology, can improve the efficacy of empirical treatment protocols. The aim of this review is to focus on the main characteristics of BSIs caused by ESBL-producing Enterobacteriaceae, with particular emphasis on risk factors for these infections and factors related to mortality.

The clinical epidemiology and outcomes of bacteremic biliary tract infections caused by antimicrobial-resistant pathogens

OBJECTIVES

The prevalence of antibiotic-resistant pathogens continues to increase steadily. The aim of this study was to analyze the changing patterns and risk factors of antibiotic resistance in patients with bacteremic biliary tract infections (BTIs). In addition, prognostic factors related to survival in patients with a bacteremic BTI were evaluated.

METHODS

Five hundred fifty-six biliary bacteremic events in 411 patients, treated from January 2000 to April 2010, were retrospectively analyzed. In addition, biliary bacteremic events were divided into nosocomial infections (N=396) and community-acquired infections (N=160).

RESULTS

The resistance rate to third-generation cephalosporin was higher in 2005-2009 (35 out of 140, 25%, vs. 72 out of 151, 47.7%). The prevalence of extended-spectrum β-lactamase-producing organisms of Escherichia coli and Klebsiella strains increased markedly from 2.3% (2 out of 86) in 2000-2004 to 43.9% (58 out of 132) in 2005-2009. Nosocomial infection, hospital days before bacteremia, previous hospitalization within 90 days, previous use of antibiotics within 90 days, and an indwelling biliary drainage catheter were found to be independently associated with antibiotic resistance. However, no association was found between antibiotic resistance and mortality in patients with biliary bacteremia.

CONCLUSIONS

Antibiotic resistance in bacteremic BTI has increased markedly during the past 10 years. Almost half of nosocomial bacteremic BTI caused by common Gram-negative pathogens during 2005-2009 (58.5%) could not be treated with third-generation cephalosporin. Clinical outcomes were found to be associated with bacteremia severity and underlying illness rather than antibiotic resistance.

Efficacy of ertapenem for treatment of bloodstream infections caused by extended-spectrum-β-lactamase-producing Enterobacteriaceae

Ertapenem is active against extended-spectrum-β-lactamase (ESBL)-producing Enterobacteriaceae organisms but inactive against Pseudomonas aeruginosa and Acinetobacter baumannii. Due to a lack of therapeutic data for ertapenem in the treatment of ESBL bloodstream infections (BSIs), group 2 carbapenems (e.g., imipenem or meropenem) are often preferred for treatment of ESBL-producing Enterobacteriaceae, although their antipseudomonal activity is unnecessary. From 2005 to 2010, 261 patients with ESBL BSIs were analyzed. Outcomes were equivalent between patients treated with ertapenem and those treated with group 2 carbapenems (mortality rates of 6% and 18%, respectively; P = 0.18).

Clinical characteristics and outcomes of patients with extended-spectrum β-lactamase-producing bacteremias in the emergency department

Extended-spectrum β-lactamase (ESBL)-producing bacteria have been spreading from hospitals to communities. Despite this, there are limited emergency department (ED) patient-based studies about these bacteremias. A retrospective matched case-control study with a ratio of 1:3 was conducted at a university hospital. The case group consisted of patients aged >16 years with ESBL-producing bacteremias in the ED. Patients matched for age and sex with non-ESBL-producing bacteremias were sampled as the control group. Finally, 64 episodes of ESBL-producing Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis bacteremias were included in our study. The median age of case patients was 71 years, and 29 (45.3%) were males. The most common type of infection was urinary tract infection (71.9%), followed by intra-abdominal infection (12.5%). Inappropriate empirical antibiotics therapy was prescribed in 87.5% of case patients, which was significantly higher than the control group (13.0%; p < 0.001). Patients with inappropriate empirical antibiotics had a significantly longer hospital stay than those with appropriate empirical antibiotics (p < 0.001). Multivariate analysis showed that hospital-acquired infection, urinary catheterization, and previous antibiotics use were independent risk factors for the acquisition of ESBL-producing bacteremia. The 28-day mortality rate of case patients was 18.8%. Whether they received appropriate empirical antibiotics treatment or not, there was no statistical difference in the mortality of patients with ESBL-producing bacteremias (p = 0.167). To face these emerging multidrug-resistant bacteria and to guide the empirical antibiotics therapy, it is crucial for emergency physicians to recognize the characteristics and risk factors for ESBL-producing organisms.

Outcome of urinary tract infections caused by extended spectrum β-lactamase-producing Enterobacteriaceae in children

The outcome of patients with urinary tract infections caused by extended spectrum β-lactamases (ESBL)-producing bacteria (cases) was compared with that of matched controls with urinary tract infections caused by non-extended spectrum β-lactamases-producing isolates. Significantly, more case patients received inappropriate empiric therapy than controls. Nevertheless, clinical and microbiologic outcomes as well as formation of renal scars did not differ between the 2 groups.

Risk factors for and outcomes associated with clinical isolates of Escherichia coli and Klebsiella species resistant to extended-spectrum cephalosporins among patients admitted to Canadian hospitals

BACKGROUND

Clinical features associated with Gram-negative bacterial isolates with extended-spectrum beta-lactamase (ESBL)- and AmpC-mediated resistance identified in Canadian hospitals is largely unknown. The objective of the present study was to determine the demographics, risk factors and outcomes of patients with ESBL- or AmpC-mediated resistant organisms in Canadian hospitals.

METHODS

Patients with clinical cultures of Escherichia coli or Klebsiella species were matched with patients with a similar organism but susceptible to third-generation cephalosporins. Molecular identification of the AmpC or ESBL was determined using a combination of polymerase chain reaction and sequence analysis. Univariate and multivariate logistic regression analysis was performed to identify variables associated with becoming a case.

RESULTS

Eight Canadian hospitals identified 106 cases (ESBL/AmpC) and 106 controls. All risk factors identified in the univariate analysis as a predictor of being an ESBL/AmpC cases at the 0.20 P-value were included in the multivariate analysis. No significant differences in outcomes were observed (unfavourable responses 17% versus 15% and mortality rates 13% versus 7%, P not significant). Multivariate logistic regression found an association of becoming an ESBL/AmpC case with: previous admission to a nursing home (OR 8.28, P=0.01) or acute care facility (OR 1.96, P=0.03), length of stay before infection (OR 3.05, P=0.004), and previous use of first-generation cephalosporins (OR 2.38, P=0.02) or third-generation cephalosporins (OR 4.52, P=0.01). Appropriate antibiotics were more likely to be given to controls (27.0% versus 13.3%, P=0.05) and number of days to appropriate antibiotics was longer for cases (median 2.8 days versus 1.2 days, P=0.05).

CONCLUSION

The importance of patient medical history, present admission and antibiotic use should be considered for all E coli or Klebsiella species patients pending susceptibility testing results.

Outcome of carbapenem resistant Klebsiella pneumoniae bloodstream infections

The aim of this study was to evaluate the impact of carbapenem-resistant K. pneumoniae bloodstream infections on mortality. During the study period 42, 68 and 120 patients were identified with carbapenem-resistant, extended-spectrum β-lactamase producers (ESBL) and susceptible K. pneumoniae bloodstream infections, respectively. Patients with carbapenem-resistant K. pneumoniae had higher rates of prior antimicrobial exposure, other nosocomial infections, and use of invasive devices. Infection-related mortality was 48% for carbapenem-resistant, 22% for ESBL producers and 17% for susceptible K. pneumoniae. Independent risk factors for infection-related mortality were Pitt bacteraemia score, Charlson score and carbapenem resistance.

Investigating the impact of the definition of previous antibiotic exposure related to isolation of extended spectrum β-lactamase-producing Klebsiella pneumoniae

BACKGROUND

Previous antibiotic exposure is a risk factor for extended spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae isolation, but the optimal definition of previous antibiotic exposure remains unclear.

METHODS

This was a retrospective, case-control study comparing 88 patients with ESBL-producing K pneumoniae (cases) and 88 patients with non-ESBL-producing K pneumoniae (controls). Three previous antibiotic exposure definitions were analyzed, including durations of 30, 60, and 90 days prior to organism isolation.

RESULTS

The mean cohort age was 63.6 ± 16.9 years, 43% were male, and 86% were black. In bivariate analysis, third-generation cephalosporins and cefepime were associated with ESBL-producing K pneumoniae isolation, and the odds ratios (OR) were significant regardless of previous antibiotic exposure definition. However, for fluoroquinolones and ampicillin/sulbactam, the ORs varied as a function of previous antibiotic exposure definition. In multivariate analysis, third-generation cephalosporin usage was a risk factor for ESBL-producing K pneumoniae isolation, whereas ampicillin/sulbactam usage was protective against these organisms, regardless of the time frame analyzed. Other independent predictors of ESBL-producing K pneumoniae included nursing home residence (OR, 9.30 [95% confidence interval: 3.69-23.43]) and hemodialysis (OR, 13.60 [95% confidence interval: 4.29-43.17]).

CONCLUSION

Prior use of third-generation cephalosporins, nursing home residence, and hemodialysis were independent risk factors for isolation of an ESBL-producing K pneumoniae regardless of the time frame analyzed.