Three separate acquisitions of blaNDM-1 in three different bacterial species from a single patient.

To investigate the acquisition and relatedness of New Delhi Metallo-beta-lactamase among multiple separate species from one patient. Five isolates from three species (Pseudomonas aeruginosa; Pa, Acinetobacter baumannii; Ab and Proteus mirabilis; Pm) suspected of harbouring a carbapenemase were investigated by phenotype (antimicrobial susceptibilities) and whole genome sequencing. Epidemiological data was collected on this patient. Three different carbapenemase genes were detected; blaVIM-1 (Pa; ST773), blaOXA-23 (Ab, ST499) and blaNDM-1 identified in all isolates. NDM regions were found chromosomally integrated in all isolates. Data showed no evidence of NDM-1 transfer within this patient suggesting the enzyme was acquired in three separate events.

Klebsiella pneumoniae ST147: and then there were three carbapenemases.

Gram-negative bacteria containing three different carbapenemases are extremely rare. Klebsiella pneumoniae (N22-925) with KPC-2, NDM-1, and OXA-48 was obtained from a Canadian patient with recent hospitalization in Romania. Short and long read whole genome sequencing showed that the blaKPC-2 was situated on a 214 kb IncFIB(K)/IncFII(K) plasmid, the blaNDM-1 on a 104 kb IncFIB (pQil)/IncFII(K) plasmid, and the blaOXA-48 on a 64 kb IncL plasmid. These plasmids were conjugated to Escherichia coli J53. N22-925 belonged to a unique ST147 cluster that is likely endemic in Romania. This case emphasizes the need for rapid carbapenemase screening in patients from endemic regions. We described the first complete genome sequence of a K. pneumoniae isolate with three different carbapenemases, providing a reference for future studies on this rarely reported occurrence.

Molecular epidemiology of Escherichia coli causing bloodstream infections in a centralized Canadian region: a population-based surveillance study.

OBJECTIVES: Escherichia coli is a leading cause of bloodstream infections worldwide, and is responsible for substantial patient morbidity, mortality and healthcare expenditure. Understanding the molecular epidemiology of E. coli will aid in designing superior treatment and prevention strategies. METHODS: We undertook a population-based surveillance study describing the clinical factors, susceptibility patterns, incidence rates and geographical distribution of sequence types (STs) among E. coli isolates (n = 686) causing incident bloodstream infections in a centralized Canadian region during 2016. STs were identified using a seven-single-nucleotide-polymorphism quantitative PCR (n = 422) and sequencing of certain house-keeping genes (n = 249). RESULTS: The annual population incidence rate of E. coli bloodstream infections was 48.8/100 000 patient years, and five dominant clones (ST131, ST73, ST69, ST95 and ST1193) accounting for 55% (378/686) of the population were identified, each with a specific geographical distribution within Calgary. ST131 was the most common (overall incidence rate of 10.4/100 000 patient years), an antimicrobial-resistant (AMR) clone affecting mainly the elderly and the very young. ST131 was common among residents in long-term care with an incidence rate of 312.5/100 000 patient years. ST73 was associated with community infections in the elderly, while ST69 and ST95 had increased incidence rates among females. ST1193 was the second most AMR clone and was associated with bloodstream infections in elderly males. CONCLUSIONS: This study showed that E. coli clones have unique characteristics in a well-defined human population. The elimination of ST131 would substantially decrease the overall incidence rate and AMR burden among E. coli bloodstream infections in the Calgary region, leading to considerable public health benefits.

Klebsiella pneumoniae ST307 with OXA-181: threat of a high-risk clone and promiscuous plasmid in a resource-constrained healthcare setting.

INTRODUCTION: Klebsiella pneumoniae with OXA-48-like enzymes were introduced into Tshwane Tertiary Hospital (TTH) (Pretoria, South Africa) during September 2015, causing nosocomial outbreaks. METHODS: PCR methodologies and WGS were used to characterize K. pneumoniae with carbapenemases (n = 124) from TTH (July 2015-December 2016). RESULTS: PCR was used to track K. pneumoniae ST307 with OXA-181 among 60% of carbapenemase-positive isolates in different wards/units over time and showed the transmission of IncX3 plasmids to other K. pneumoniae clones. WGS identified different ST307 clades: 307_OXA181 (consisting of two lineages, A and B) with OXA-181 on IncX3 plasmids (named p72_X3_OXA181) and clade 307_VIM with VIM-1 on IncFII plasmids. Clade 307_OXA181 lineage B was responsible for the rapid increase and transmission of OXA-181 K. pneumoniae in various wards/units throughout TTH, while the numbers of clade 307_OXA181 lineage A and clade 307_VIM remained low. Separate outbreaks were due to K. pneumoniae ST17 and ST29 with p72_X3_OXA181 plasmids. CONCLUSIONS: The high-risk clone K. pneumoniae ST307 with OXA-181 rapidly spread to different wards/units despite infection and prevention measures. ST307 clades and lineages seemingly acted differently in outbreak situations. This study also highlighted the threat of promiscuous plasmids such as p72_X3_OXA181.

Deciphering risk factors for blood stream infections, bacteria species and antimicrobial resistance profiles among children under five years of age in North-Western Tanzania: a multicentre study in a cascade of referral health care system.

BACKGROUND: Blood stream infections (BSIs) cause a complex cascade of inflammatory events, resulting in significant morbidity and mortality in children in Tanzania. This study was designed to delineate circulating bacterial species, antimicrobial resistance (AMR) profiles and risk factors for BSIs and mortality among children in the cascade of referral health care facilities so as to guide comprehensive BSIs management. METHODS: A multiple cross sectional analytical study was conducted between July 20, 2016 to October 04, 2017 involving 950 children less than five years of age in the North-western part of Tanzania. Children with clinical features suggestive of BSIs were included. Demographic, clinical and laboratory information on culture and antimicrobial susceptibility testing was collected from children; and analyzed using STATA version 13.0 software. RESULTS: The prevalence of BSIs among children was 14.2% (95% CI: 12.1-16.6%), with specific prevalence in the district, regional and tertiary hospitals being 8.3, 6.4 and 20.0%, respectively. The most common bacterial pathogens isolated from 135 culture-positive children were Klebsiella pneumoniae (55, 40.4%), Staphylococcus aureus (23, 17.0%), and Escherichia coli (17, 12.6%). Multi-drug resistance (MDR) was higher in isolates from children at Bugando Medical Centre (BMC) tertiary hospital than isolates from district and regional hospitals [OR (95% CI): 6.36 (2.15-18.76); p = 0.001]. Independent risk factors for BSIs were neonatal period [OR (95% CI): 1.93 (1.07-3.48); p = 0.003] and admission at BMC [2.01 (1.08-3.74); p = 0.028)]. Approximately 6.6% (61/932) of children died, and risk factors for mortality were found to be children attending BMC [OR (95% CI): 4.95 (1.95-12.5); p = 0.001)], neonatal period [OR (95% CI): 2.25 (1.02-5.00); p = 0.045)], and children who had blood culture positive results [OR (95% CI): 1.95 (1.07-3.56); p = 0.028)]. CONCLUSIONS: The prevalence of BSIs (14.2%) in this multi-centre study is high and predominantly caused by the MDR K. pneumoniae. Priority interventional measures to combat BSIs and mortality, specifically among neonates at BMC are urgently recommended.

Multicentre evaluation of significant bacteriuria among pregnant women in the cascade of referral healthcare system in North-western Tanzania: Bacterial pathogens, antimicrobial resistance profiles and predictors.

OBJECTIVES: The aim of this multicentre study was to evaluate the magnitude of significant bacteriuria (SB) as well as the implicated bacterial pathogens, antimicrobial resistance (AMR) profiles and risk factors for SB among pregnant women attending different levels of healthcare facilities (HCFs) in Tanzania in order to guide antimicrobial therapy and preventive measures. METHODS: Information on sociodemographic and clinical characteristics, midstream urine culture and antimicrobial susceptibility testing was collected from 1828 pregnant women between March 2016 and May 2017. Data were analysed using STATA v.13.0 software. RESULTS: The prevalence of SB among pregnant women was 17.7% (323/1828; 95% CI 16.0-19.5%), with a predominance of Escherichia coli (164/323; 50.8%), Klebsiella spp. (55/323; 17.0%) and Staphylococcus aureus (28/323; 8.7%). Moreover, 37.5% (121/323) of bacteria were multidrug-resistant [84.3% (102/121) Gram-negative bacteria and 15.7% (19/121) in Gram-positive bacteria; P<0.001]. Third-generation cephalosporin resistance in E. coli, Klebsiella spp. and other Enterobacteriaceae was 13.4%, 21.8% and 27.5%, respectively, and was higher in strains from a tertiary hospital (OR=3.27, 95% CI 1.02-10.49; P=0.046) compared with lower HCFs. Predictors of SB among pregnant women were lack of formal occupation, current hospital admission and presence of co-morbidities. CONCLUSIONS: The prevalence of SB among pregnant women in this study was high (17.7%) and was within the same range reported 10 years ago in a single-centre baseline study. However, there is an increase in AMR in the cascade of referral healthcare system, underscoring the need for health facility level-specific antimicrobial stewardship.

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

PURPOSE: There are few data in the literature regarding sepsis or septic shock due to extended-spectrum ß-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. ß-lactam/ß-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.

Preliminary insights into the occurrence of similar clones of extended-spectrum beta-lactamase-producing bacteria in humans, animals and the environment in Tanzania: A systematic review and meta-analysis between 2005 and 2016.

The emergence and spread of extended-spectrum beta-lactamase producing Enterobacteriaceae (ESBL-PE) are complex and of the public health concern across the globe. This review aimed at assessing the ESBL-PE clones circulating in humans, animals and the environment to provide evidence-based insights for combating ESBL-PE using One Health approach. Systematic search from Medline/PubMed, Google Scholar and African Journals Online was carried out and retrieved nine eligible articles (of 131) based on phenotypic and genotypic detection of ESBL-PE between 2005 and 2016 in Tanzania. Analysis was performed using STATA 11.0 software to delineate the prevalence of ESBL-PE, phenotypic resistance profiles and clones circulating in the three interfaces. The overall prevalence of ESBL-PE in the three interfaces was 22.6% (95% CI: 21.1-24.2) with the predominance of Escherichia coli (E. coli) strains (51.6%). The majority of ESBL-PE were resistant to the commonly used antimicrobials such as trimethoprim-sulfamethoxazole and tetracycline/doxycycline, 38%-55% were resistant to ciprofloxacin and all were sensitive to meropenem/imipenem. ESBL-PE infections were more associated with deaths compared to non-ESBL-PE infections. Strikingly, E. coli ST38, ST131 and ST2852 were found to intersect variably across the three interfaces. The predominant allele, blaCTX-M-15, was found mostly in the conjugative IncF plasmids connoting transmission potential. The high prevalence of ESBL-PE and shared clones across the three interfaces, including the global E. coli ST131 clone, indicates wide and inter-compartmental spread that calls for One Health genomic-driven studies to track the resistome flow.

Genomic epidemiology of global Klebsiella pneumoniae carbapenemase (KPC)-producing Escherichia coli.

The dissemination of carbapenem resistance in Escherichia coli has major implications for the management of common infections. bla KPC, encoding a transmissible carbapenemase (KPC), has historically largely been associated with Klebsiella pneumoniae, a predominant plasmid (pKpQIL), and a specific transposable element (Tn4401, ~10 kb). Here we characterize the genetic features of bla KPC emergence in global E. coli, 2008-2013, using both long- and short-read whole-genome sequencing. Amongst 43/45 successfully sequenced bla KPC-E. coli strains, we identified substantial strain diversity (n = 21 sequence types, 18% of annotated genes in the core genome); substantial plasmid diversity (≥9 replicon types); and substantial bla KPC-associated, mobile genetic element (MGE) diversity (50% not within complete Tn4401 elements). We also found evidence of inter-species, regional and international plasmid spread. In several cases bla KPC was found on high copy number, small Col-like plasmids, previously associated with horizontal transmission of resistance genes in the absence of antimicrobial selection pressures. E. coli is a common human pathogen, but also a commensal in multiple environmental and animal reservoirs, and easily transmissible. The association of bla KPC with a range of MGEs previously linked to the successful spread of widely endemic resistance mechanisms (e.g. bla TEM, bla CTX-M) suggests that it may become similarly prevalent.

Colistin-Nonsusceptible Pseudomonas aeruginosa Sequence Type 654 with blaNDM-1 Arrives in North America.

This study describes 3 different blaNDM-1 genetic platforms in 3 different species obtained from the same patient who was directly transferred to an institution in Calgary, Alberta, Canada, following a prolonged hospital stay in India. The blaNDM-1 in the Escherichia coli isolate was located on a 176-kb IncA/C plasmid contained within an ISCR1 region. The blaNDM-1 in the Providencia rettgeri isolate was located on a 117-kb IncT plasmid contained within Tn3000, while the blaNDM-1 in the Pseudomonas aeruginosa isolate was located on the chromosome within an ISCR3 region. This report highlights the plasticity of the genetic regions and environments associated with blaNDM-1. To the best of our knowledge, this is the first report of P. aeruginosa with blaNDM-1 identified in North America and the first report of blaOXA-181 in P. rettgeri. The P. aeruginosa isolate belonged to the international high-risk sequence type 654 clone and was nonsusceptible to colistin. This case emphasizes the need for the use of appropriate infection prevention and control measures and vigilant screening for carbapenem-resistant Gram-negative bacteria in patients with a history of travel to areas of endemicity, such as the Indian subcontinent.

Molecular Characterization by Using Next-Generation Sequencing of Plasmids Containing blaNDM-7 in Enterobacteriaceae from Calgary, Canada.

Enterobacteriaceae with blaNDM-7 are relatively uncommon and had previously been described in Europe, India, the United States, and Japan. This study describes the characteristics of Enterobacteriaceae (Klebsiella pneumoniae [n = 2], Escherichia coli [n = 2], Serratia marcescens [n = 1], and Enterobacter hormaechei [n = 1] isolates) with blaNDM-7 obtained from 4 patients from Calgary, Canada, from 2013 to 2014. The 46,161-bp IncX3 plasmids with blaNDM-7 are highly similar to other blaNDM-harboring IncX3 plasmids and, interestingly, showed identical structures within the different isolates. This finding may indicate horizontal transmission within our health region, or it may indicate contact with individuals from areas of endemicity within the hospital setting. Patients infected or colonized with bacteria containing blaNDM-7 IncX3 plasmids generate infection control challenges. Epidemiological and molecular studies are required to better understand the dynamics of transmission, the risk factors, and the reservoirs for bacteria harboring blaNDM-7. To the best of our knowledge, this is the first report of S. marcescens and E. hormaechei with blaNDM-7.

Incidence, risk factors, and outcomes for Enterococcus spp. blood stream infections: a population-based study.

BACKGROUND: Enterococci are a clinically significant cause of bloodstream infections (BSI), particularly in the nosocomial setting. The purpose of this study was to characterize the incidence, risk factors for acquisition, microbiological characteristics and mortality of enterococcal BSI within the well-defined population of a large Canadian health region. METHODS: Surveillance for all episodes of enterococcal BSI occurring among residents of the Calgary Health Zone (population 1.2 million) between 2000 and 2008 was conducted using an electronic surveillance system. Clinical features, microbiology, and outcomes were obtained. RESULTS: A total of 710 incident episodes of enterococcal BSI were identified for an annual incidence of 6.9 episodes per 100,000; the incidences of E. faecalis and E. faecium BSI were 4.5, and 1.6 per 100,000, respectively. Enterococcus faecalis infections were associated with a urinary focus, genitourinary malignancy, and abnormal genitourinary anatomy. E. faecium infections were associated with a gastrointestinal focus. Resistance to ampicillin, vancomycin and ciprofloxacin was higher in E. faecium infection. The overall case fatality rate was 22.8%, and was higher for E. faecium infection. CONCLUSIONS: This is the second population-based study to assess the risk factors for enterococcal BSI and compare the characteristics of infection with E. faecalis and E. faecium. Results suggest that BSI with E. faecalis and E. faecium should be regarded as two clinically different entities with unique sets of risk factors and microbiologic characteristics.

Population-based assessment of the incidence, risk factors, and outcomes of anaerobic bloodstream infections.

BACKGROUND: Anaerobes are a relatively uncommon but important cause of bloodstream infection. However, their epidemiology has not been well defined in non-selected populations. We sought to describe the incidence of, risk factors for, and outcomes associated with anaerobic bacteremia. METHODS: Population-based surveillance for bacteremia with anaerobic microorganisms was conducted in the Calgary area (population 1.2 million) during the period from 2000 to 2008. RESULTS: A total of 904 incident cases were identified, for an overall population incidence of 8.7 per 100,000 per year; 231 (26 %) were nosocomial, 300 (33 %) were healthcare-associated community-onset, and 373 (41 %) were community-acquired. Elderly males were at the greatest risk. The most common pathogens identified were: Bacteroides fragilis group (3.6 per 100,000), Clostridium (non-perfringens) spp. (1.1 per 100,000), Peptostreptococcus spp. (0.9 per 100,000), and Clostridium perfringens (0.7 per 100,000). Non-susceptibility to metronidazole was 2 %, to clindamycin 17 %, and to penicillin 42 %. Relative to the general population, risk factors for anaerobic bloodstream infection included: male sex, increasing age, a prior diagnosis of cancer, chronic liver disease, heart disease, diabetes mellitus, stroke, inflammatory bowel disease, human immunodeficiency virus (HIV) infection, chronic obstructive pulmonary disease (COPD), and/or hemodialysis-dependent chronic renal failure (HDCRF). The 30-day mortality was 20 %. Increasing age, nosocomial acquisition, presence of malignancy, and several other co-morbid illnesses were independently associated with an increased risk of death. CONCLUSION: Anaerobic bloodstream infection is responsible for a significant burden of disease in general populations. The data herein establish the extent to which anaerobes contribute to morbidity and subsequent mortality. This information is key in developing preventative, empiric treatment and research priorities.

Metallo-ß-lactamase-producing Pseudomonas aeruginosa in the Netherlands: the nationwide emergence of a single sequence type.

Recently, the first outbreak of clonally related VIM-2 metallo-ß-lactamase (MBL)-producing Pseudomonas aeruginosa in a Dutch tertiary-care centre was described. Subsequently, a nationwide surveillance study was performed in 2010-2011, which identified the presence of VIM-2 MBL-producing P. aeruginosa in 11 different hospitals. Genotyping by multiple-locus variable-number tandem-repeat analysis (MLVA) showed that the majority of the 82 MBL-producing isolates found belonged to a single MLVA type (n = 70, 85%), identified as ST111 by multilocus sequence typing (MLST). As MBL-producing isolates cause serious infections that are difficult to treat, the presence of clonally related isolates in various hospitals throughout the Netherlands is of nationwide concern.

Molecular characteristics of extended-spectrum ß-lactamase-producing Escherichia coli from Rio de Janeiro, Brazil.

Twenty-five extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli clinical isolates from Rio de Janeiro, Brazil were characterized by isoelectric focusing, PCR and sequencing of bla(ESBL) genes, plasmid-mediated quinolone resistance determinants, phylogenetic groups, replicon typing, pulsed-field electrophoresis, and multilocus sequencing typing. Twenty-three (92%) ESBL-producing E. coli isolates were positive for bla(CTX-M) genes, aac(6')-Ib-cr, and qnrB. Genetic relatedness of ESBL producers clustered seven (28%) CTX-M-15-producing isolates as sequence type (ST)410, clonal complex (CC) 23, and two (8%) as clone O25-ST131. Our results illustrate the predominance of phylogroup A (52%), ST410 (CC 23) and CTX-M-15 among ESBL-producing E. coli isolates from hospitals in Rio de Janeiro.

Phylogenetic diversity of Escherichia coli strains producing NDM-type carbapenemases.

BACKGROUND: The global accumulation of Escherichia coli with CTX-M extended-spectrum ß-lactamases partly reflects the dissemination of clonal lineages, notably ST131 and ST405. More recently, E. coli have emerged that produce NDM carbapenemase. We sought to determine the clonal diversity of E. coli with this enzyme from English hospitals, and to compare them with isolates from Pakistan and India. METHODS: The 18 NDM-positive E. coli were from hospitals in England (n = 10), Pakistan (n = 7) and India (n = 1). Isolates were compared by phylogenetic grouping, multilocus sequence typing and PFGE of XbaI-digested DNA. Isolates were screened by PCR for acquired AmpC genes, bla(CTX-M), and the 16S rRNA methylase genes armA and rmtC. RESULTS: Most of the isolates belonged to phylogenetic groups B1 (n = 9) or D (n = 7); two were group A and none was group B2. Nine isolates from England and Pakistan belonged to the B1 lineage ST101, with seven of these clustering at >77% similarity by PFGE. Other lineages included ST405 (n = 3, group D), ST648 (n = 3, group D), the ST23 complex (one each of ST90 and ST410, both group A) and ST156 (n = 1, group D). Sixteen of 18 isolates had a group 1 CTX-M gene, 13 had a CIT-type acquired AmpC, and 16 had either or both of armA and rmtC. CONCLUSIONS: The E. coli isolates producing NDM-1 carbapenemase belonged to six sequence types and included diverse clonal lineages. Nevertheless, isolates of B1-ST101 accounted for half the collection, and included isolates from both England and Pakistan. None of the isolates belonged to ST131 or to phylogroup B2.

First outbreak of VIM-2 metallo-ß-lactamase-producing Pseudomonas aeruginosa in The Netherlands: microbiology, epidemiology and clinical outcomes.

This study was designed to investigate the prevalence and characteristics of metallo-ß-lactamase (MBL)-producing Pseudomonas aeruginosa in a tertiary care centre in The Netherlands, a country that is considered to have a low prevalence of antibiotic-resistant bacteria. Imipenem-resistant P. aeruginosa isolates cultured from clinical specimens during 2008-2009 were analysed phenotypically and molecularly by polymerase chain reaction (PCR) with sequencing. Genotyping was performed by multiple-locus variable-number tandem repeat (VNTR) analysis (MLVA). Clinical information was obtained by electronic chart review for all patients infected or colonised with an imipenem-resistant P. aeruginosa isolate that was included in the study. In total, 106 imipenem-resistant P. aeruginosa isolates were included. The bla(VIM-2) gene was detected in 35/106 isolates (33%) and was associated with integrons. Compared with non-MBL-producing imipenem-resistant P. aeruginosa, VIM-2 MBL-producing isolates showed higher rates of multidrug resistance. Patients with VIM-2 MBL-producing isolates were more likely to be admitted to the Intensive Care Unit (ICU) and had a higher risk of invasive infection, including development of bacteraemia. MLVA identified two separate VIM-2 MBL-producing clones, responsible for outbreaks in the ICU but also affecting 10 other departments. This is the first reported outbreak of VIM-2 MBL-producing P. aeruginosa in The Netherlands. Once introduced, VIM-2 MBL-producing P. aeruginosa cause significant infections and are easily spread within the hospital setting.

Population-based study of the epidemiology and the risk factors for Pseudomonas aeruginosa bloodstream infection.

BACKGROUND: Detailed population-based data on the epidemiology of Pseudomonas aeruginosa bloodstream infections are sparse. We sought to describe the incidence rate, risk factors, and outcomes associated with P. aeruginosa bacteremia in a large Canadian health region. PATIENTS AND METHODS: A retrospective population-based surveillance for P. aeruginosa bacteremia was conducted in the Calgary Health Region (CHR, population:approx. 1.2 million) during the period from 2000 to 2006. RESULTS: A total of 284 incident cases of P. aeruginosa bacteremia were identified in CHR residents, corresponding to an annual incidence rate of 3.6/100,000.Nosocomial acquisition accounted for 45% of cases,healthcare-associated community onset for 34% of cases,and community-acquired (CA) cases for 21%. Relative to the general population, risk factors for blood stream infection included male sex, increasing age, hemodialysis,solid organ transplant, diagnosis of cancer, heart disease, HIV infection, diabetes mellitus, and/or chronic obstructive airway disease (COPD). Overall mortality was 29%. Factors associated with mortality in univariate analysis included pulmonary focus of infection and co-morbidities, including chronic liver disease, substance abuse, heart disease, COPD, and cancer, and increased with the burden of co-morbidities. Despite those patients with CA disease having fewer co-morbidities,they had a significantly higher mortality rate than either healthcare-associated cases or nosocomial cases(RR 1.88, p = 0.05). CONCLUSIONS: This study documents that P. aeruginosa bacteremic disease is responsible for a significant burden of illness in general populations and identifies those groups at increased risk of infection and subsequent mortality. This information can be used to identify those individuals likely to benefit from empiric anti-pseudomonal therapies.

Detection of AmpC beta-lactamases in Escherichia coli, Klebsiella spp., Salmonella spp. and Proteus mirabilis in a regional clinical microbiology laboratory.

There are currently no standardized diagnostic tests available for the reliable detection of AmpC beta-lactamases in Klebsiella spp., Escherichia coli, Proteus mirabilis and Salmonella spp. A study was designed to evaluate a confirmation disk test using cefotetan (CTT) and cefoxitin (FOX) with phenylboronic acid (PBA). It also investigated the most suitable screening concentrations of FOX, ceftriaxone (CRO) and ceftazidime (CAZ) for the detection of AmpC beta-lactamases. A total of 126 control (consisting of 11 laboratory and 115 well-characterized clinical strains) and 29,840 non-repeat clinical isolates were included. FOX with PBA used in a confirmation test and CRO and CAZ as screening agents were found to be unreliable. FOX at >or= 32 mg/L was the best screening agent and CTT with PBA was the best confirmation test. Of the clinical isolates 635 (2%) were found to be resistant to cefoxitin (MIC >or= 32 ug/mL) and 332 (52%) were AmpC positive. E. coli was the most common organism with AmpC beta-lactamases and was mostly present in urines from community patients. It is recommended that laboratories use FOX at 32 mg/L as a screening agent and perform a disk test with CTT and PBA to confirm the presence of an AmpC cephalosporinase in isolates of Klebsiella spp., E. coli, Salmonella spp. and P. mirabilis. This approach is convenient, practical and easy to incorporate into the workflow of a clinical laboratory. False-positive AmpC detection may occur with KPC-producing bacteria when inhibitor-based methods are used.

Incidence, risk factors and outcomes of Escherichia coli bloodstream infections in a large Canadian region.

Although Escherichia coli is the most common cause of bloodstream infection, its epidemiology has not been well defined in non-selected populations. We sought to describe the incidence of risk factors for, and outcomes associated with, E. coli bacteraemia. Population-based surveillance for E. coli bacteraemia was conducted in the Calgary Health Region (population 1.2 million) during the period 2000-2006. In total, 2368 episodes of E. coli bacteraemia were identified for an overall annual population incidence of 30.3/100 000; 15% were nosocomial, 32% were healthcare-associated community-onset and 53% were community-acquired bacteraemias. The very young and the elderly were at highest risk for E. coli bacteraemia. Sixty per cent of the episodes occurred in females (relative risk 1.5; 95% CI 1.4-1.6). Dialysis, solid organ transplantation and neoplastic disease were the most important risk factors for acquiring E. coli bacteraemia. Rates of resistance to ampicillin, trimethoprim-sulphamethoxazole, gentamicin, ciprofloxacin, cefazolin and ceftriaxone increased significantly during the period 2000-2006. The case-fatality rate was 11% and the annual population mortality rate was 2.9/100 000. Increasing age, ciprofloxacin resistance, non-urinary focus and a number of comorbid illnesses were independently associated with an increased risk of death, and community acquisition and urinary focus were associated with a lower risk of death. This study documents the major burden of illness associated with E. coli bacteraemia and identifies groups at increased risk for acquiring and dying from these infections. The emergence of ciprofloxacin resistance and its adverse effect on patient outcome is a major concern.