Extended-spectrum β-lactamases: implications for the clinical microbiology laboratory, therapy, and infection control

Long-lasting Effects of Control Measures on Trends in Incidence in Neonatal Late-onset Sepsis due to Multiresistant Bacteria in a Brazilian Neonatal Unit

BACKGROUND

In 1995, due an outbreak of sepsis caused by multiresistant (MR) Gram-negative bacteria (GNB) our neonatal unit established a series of control and prevention measures. This study assessed the long-term impact of these measures on late-onset neonatal sepsis (LONS) caused by MR bacteria in a Brazilian level III neonatal unit from 2000 to 2020 and examined its relationship with in-hospital death.

METHODS

Newborns with LONS, confirmed by positive blood and/or cerebrospinal fluid cultures caused by Staphylococcus aureus, GNB, and Enterococcus sp, were analyzed. MR criteria followed CDC and local infectious disease guidelines. The annual sepsis trend was evaluated using joinpoint regression analysis.

RESULTS

Over 21 years, the confirmed LONS rate was 4.6%, showing a significant decline from 2000 to 2016 (P <.0001, negative slope of -0.36). From 2016 to 2020, there was a non-significant increase (slope = +0.92, P =.08). MR agents were present in 36/227 cases of sepsis (15.8%). MR sepsis showed a non-significant upward trend (slope = +0.50, P =.08) without inflection points. In-hospital death rates for MR LONS did not differ significantly from non-MR LONS (37.1% vs. 30.1%, P =.413).

DISCUSSION

The study indicates a low prevalence of MR sepsis due to effective antimicrobial use and educational interventions.

CONCLUSION

MR sepsis prevalence remained low and stable, not increasing in-hospital mortality.

Molecular characterization of extended-spectrum β-lactamases-producing Enterobacteriaceae species in ground beef and chicken meat

The objectives of this study were i) to characterize extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) using pheno- and genotyping methods, ii) to evaluate the antimicrobial resistance pattern against 10 antibiotics, and iii) to investigate class 1 integron (intI1) in 80 Enterobacteriaceae isolates obtained from chicken meat (n = 40; 47 isolates) and ground beef (n = 40; 33 isolates) samples. Through the study, we found that 55 (68.7 %) of 80 Enterobacteriaceae isolates were capable of β-lactamase activity, and 38 (47.5 %) of them were multi-drug-resistant (MDR). The ground meat-origin isolates are 1.2 times more likely to produce imipenem resistance compared to chicken-meat-origin isolates (z = 2.1, p < 0.05, OR = 1.42). ESBL-E was found in 18 (22.5 %) of the isolates, 16.3 % of chicken meat and 6.3 % of ground beef origin. The bla genes were detected in 14 isolates [bla-_TEM (n = 10; 12.5 %); bla-_SHV (n = 4; 5.0 %); bla-_CTX-M (n = 0)], where the predominant species were Escherichia (E.) coli and Citrobacter braakii. The nine ESBL-E isolates were MDR. Twenty-eight (35.0 %) of 80 isolates were found to be resistant to at least one third-generation cephalosporin, and eight (28.6 %) of them were also ESBL-E. Eleven of 16 (48.5 %) carbapenem-resistant isolates were ESBL-E. The intI1 gene was found in 13 (16.3 %) isolates, five of which were ESBL-E, and four of which were MDR. Co-existing with bla-_TEM and the intI1 isolate was ESBL-E. coli, which was resistant to nine antibiotics. In conclusion, chicken meat and ground beef may pose a potential risk of containing ESBL-E, and bla genes which could be spread to the entire food chain.

Evaluation of Antibiotic Resistance of Salmonella Serotypes and Whole-Genome Sequencing of Multiresistant Strains Isolated from Food Products in Russia

Food products may be a source of Salmonella, one of the main causal agents of food poisoning, especially after the emergence of strains resistant to antimicrobial preparations. The present work dealt with investigation of the occurrence of resistance to antimicrobial preparations among S. enterica strains isolated from food. The isolates belonged to 11 serovars, among which Infantis (28%), Enteritidis (19%), and Typhimurium (13.4%) predominated. The isolates were most commonly resistant to trimethoprim/sulfamethoxazole (n = 19, 59.38%), cefazolin (n = 15, 46.86%), tetracycline (n = 13, 40.63%), and amikacin (n = 9, 28.13%). Most of the strains (68.75%) exhibited multiple resistance to commonly used antibiotics. High-throughput sequencing was used to analyse three multidrug-resistant strains (resistant to six or more antibiotics). Two of them (SZL 30 and SZL 31) belonged to S. Infantis, while one strain belonged to S. Typhimurium (SZL 38). Analysis of the genomes of the sequenced strains revealed the genes responsible for antibiotic resistance. In the genomes of strains SZL 30 and SZL 31 the genes of antibiotic resistance were shown to be localized mostly in integrons within plasmids, while most of the antibiotic resistance genes of strain SZL 38 were localized in a chromosomal island (17,949 nt). Genomes of the Salmonella strains SZL 30, SZL 31, and SZL 38 were shown to contain full-size pathogenicity islands: SPI-1, SPI-2, SPI-4, SPI-5, SPI-9, SPI-11, SPI-13, SPI-14, and CS54. Moreover, the genome of strain SZL 38 was also found to contain the full-size pathogenicity islands SPI-3, SPI-6, SPI-12, and SPI-16. The emergence of multidrug-resistant strains of various Salmonella serovars indicates that further research on the transmission pathways for these genetic determinants and monitoring of the distribution of these microorganisms are necessary.

Effects of modified atmosphere packaging on an extended-spectrum beta-lactamase-producing Escherichia coli, the microflora, and shelf life of chicken meat

The effects of modified atmosphere packaging on an extended-spectrum beta-lactamase-producing Escherichia coli strain and product quality characteristics of skinless chicken meat were determined. The samples were packed separately in air, 100% N2, and prefabricated gas mixtures with 75% O2 + 25% CO2 and 70% CO2 + 15% O2 + 15% N2 and incubated at 3°C for 7 d. To investigate the influence of the headspace ratio, samples were packed in identical trays to 600 g and 120 g. After 0, 2, 5, and 7 d of incubation, the samples were analyzed microbiologically and photometrically, and pH was measured. The results show that the development of the microorganisms depends on the atmosphere, with the 70% CO2 + 15% O2 + 15% N2 atmosphere having the highest development-inhibiting effect. This effect is increased with increased headspace. No significant effects on the pH and color of the samples were observed.

Comparison between Exposure of Ciprofloxacin and Cefotaxime on Developing of Escherichia coli ESBL

This study aimed to compare ciprofloxacin and cefotaxime exposure to develop ESBL producing Escherichia coli (E. coli). A total of 16 isolates of cefotaxime sensitive E. coli and ciprofloxacin were exposed to ciprofloxacin and cefotaxime for 14 days using the Kirby-Bauer antibiotic disc diffusion method. Colonies that grew on the edge of the inhibiting zone were exposed each day by the same method. Furthermore, we observed the occurrence of resistance to cefotaxime as ESBL screening test. Isolates were resistant, the following day the ESBL was confirmed by the Modified Double Disk Sinergy Test (MDDST) method using Cefotaxime (CTX), Ceftazidime (CAZ), Aztreonam (ATM), and Amoxilin Clavulanate (AMC) antibiotic discs. From 16 isolates of ESBL producing E. coli exposed to ciprofloxacin, it was obtained 4 (25%) to ESBL E. coli. ESBL production occurred after E. coli was exposed to ciprofloxacin on days 5, 6, 7, and 12. While those exposed to cefotaxime none becomes ESBL E. coli. There was no difference between ciprofloxacin and cefotaxime exposure to develop ESBL producing E. coli (p=0.101; Chi-square).

Complete Genome Sequence of Proteus mirabilis Phage Mydo

Proteus mirabilis is a pathogen that has been linked to nosocomial infections. Studies on phages infecting P. mirabilis may provide therapeutics for infections caused by antibiotic-resistant strains of this pathogen. Here, we announce the complete genome sequence of a P. mirabilis myophage, Mydo, which is distantly related to Escherichia coli phage rv5.

Proteus mirabilis is a pathogen that has been linked to nosocomial infections. Studies on phages infecting P. mirabilis may provide therapeutics for infections caused by antibiotic-resistant strains of this pathogen. Here, we announce the complete genome sequence of a P. mirabilis myophage, Mydo, which is distantly related to Escherichia coli phage rv5.

First report of blaOXA-24 carbapenemase gene, armA methyltransferase and aac(6')-Ib-cr among multidrug-resistant clinical isolates of Proteus mirabilis in Algeria

OBJECTIVE

Carbapenemase-producing, or carbapenem-resistant, Enterobacteriaceae are an emerging threat to human and animal health because they are resistant to many of the last-line antimicrobials available for treatment of infection. The aim of this study was to analyse the antimicrobial resistance patterns and their encoding genes of Proteus mirabilis isolated in Constantine, Algeria.

METHODS

A total of 108 Proteus, Morganella and Providencia (PMP) strains were isolated from a large variety of clinical specimens at University Hospital of Constantine in Algeria. Isolates were identified using the API 20E system and matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Diagnostic accuracy was determined by independent comparison of each method to phylogenetic analysis based on 16S rRNA gene sequencing. Antimicrobial susceptibility was determined by the standard disk diffusion and Etest methods. The presence of antimicrobial resistance genes was screened for by PCR amplification and sequencing.

RESULTS

A total of 72 PMP strains were multidrug-resistant (MDR). Among them, one P. mirabilis isolate was resistant to imipenem with a minimum inhibitory concentration (MIC) of ≥12μg/mL. PCR and sequencing showed the presence of various antimicrobial resistance genes, including bla_CTX-M-15, bla_TEM-1, bla_TEM-2, bla_PER-1, bla_SHV-11, aadA1, aadA2, armA, aac(6')-Ib, aac(6')-Ib-cr, aac(3)-Ia and ant(2″)-I, forming different resistance profiles. Moreover, the bla_OXA-24 gene was detected in the imipenem-resistant P. mirabilis strain.

CONCLUSION

In this study, a MDR P. mirabilis isolate harbouring the bla_OXA-24, armA 16S rRNA methylase and aac(6)-Ib-cr genes was found for the first time in Algeria.

Prevalence and antimicrobial susceptibility patterns of extended spectrum beta-lactamase producing Entrobacteriaceae in the University of Gondar Referral Hospital environments, northwest Ethiopia

OBJECTIVE

This study aimed at assessing the magnitude, distribution, and the antimicrobial susceptibility of the extended spectrum beta-lactamase producing Entrobacteriaceae in the University of Gondar Referral Hospital environments.

RESULTS

Out of a total of 384 samples, 14.8% were ESBL producing Entrobacteriaceae, where 42.10% Klebsiella pneumoniae, 35.09% Escherchia coli and 7.01% Proteus mirabilis were the predominant isolates. Most ESBL producing isolates, that is, 24.56, 22.8, and 22.8% were found from waste water, sinks and bedside tables respectively. All ESBL producing Entrobacteriaceae were found to be resistant to ceftriaxone, ceftazidime, cefpirome, cefpodoxime, and amoxicillin with Clavulanic acid. Resistance rate was also high for non-beta-lactam antimicrobials, like chloramphenicol (70.18%), cotrimoxazole (64.91%), norfloxacin (42.10%), ciprofloxacin (43.86%), and gentamicin (19.30%).

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, bla_CTX-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.

Feeding of waste milk to Holstein calves affects antimicrobial resistance of Escherichia coli and Pasteurella multocida isolated from fecal and nasal swabs

The use of milk containing antimicrobial residues in calf feeding programs has been shown to select for resistant fecal Escherichia coli in dairy calves. However, information is scarce about the effects of feeding calves waste milk (WM) on the prevalence of multidrug-resistant bacteria. The objective of this study was to determine the antimicrobial resistance patterns of fecal E. coli and nasal Pasteurella multocida isolates from calves fed either milk replacer (MR) or WM in 8 commercial dairy farms (4 farms per feeding program). Fecal and nasal swabs were collected from 20 ± 5 dairy calves at 42 ± 3.2 d of age, and from 10 of these at approximately 1 yr of age in each study farm to isolate the targeted bacteria. Furthermore, resistance of E. coli isolates from calf-environment and from 5 calves at birth and their dams was also evaluated in each study farm. Resistances were tested against the following antimicrobial agents: amoxicillin-clavulanic acid, ceftiofur, colistin, doxycycline (DO), enrofloxacin (ENR), erythromycin, florfenicol, imipenem, and streptomycin. A greater number of fecal E. coli resistant to ENR, florfenicol, and streptomycin and more multidrug-resistant E. coli phenotypes were isolated in feces of calves fed WM than in those fed MR. However, the prevalence of fecal-resistant E. coli was also influenced by calf age, as it increased from birth to 6 wk of age for ENR and DO and decreased from 6 wk to 1 yr of age for DO regardless of the feeding program. From nasal samples, an increase in the prevalence of colistin-resistant P. multocida was observed in calves fed WM compared with those fed MR. The resistance patterns of E. coli isolates from calves and their dams tended to differ, whereas similar resistance profiles among E. coli isolates from farm environment and calves were observed. The findings of this study suggest that feeding calves WM fosters the presence of resistant bacteria in the lower gut and respiratory tracts of dairy calves.

Characterization of CTX-M enzymes, quinolone resistance determinants, and antimicrobial residues from hospital sewage, wastewater treatment plant, and river water

Multidrug-resistant (MDR) bacteria are widespread in hospitals and have been increasingly isolated from aquatic environments. The aim of the present study was to characterize extended-spectrum β-lactamase (ESBL) and quinolone-resistant Enterobacteriaceae from a hospital effluent, sanitary effluent, inflow sewage, aeration tank, and outflow sewage within a wastewater treatment plant (WWTP), as well as river water upstream and downstream (URW and DRW, respectively), of the point where the WWTP treated effluent was discharged. β-lactamase (bla) genes, plasmid-mediated quinolone resistance (PMQR), and quinolone resistance-determining regions (QRDRs) were assessed by amplification and sequencing in 55 ESBL-positive and/or quinolone-resistant isolates. Ciprofloxacin residue was evaluated by high performance liquid chromatography. ESBL-producing isolates were identified in both raw (n=29) and treated (n=26) water; they included Escherichia coli (32), Klebsiella pneumoniae (22) and Klebsiella oxytoca (1). Resistance to both cephalosporins and quinolone was observed in 34.4% of E. coli and 27.3% of K. pneumoniae. Resistance to carbapenems was found in 5.4% of K. pneumoniae and in K. oxytoca. Results indicate the presence of bla_CTX-M (51/55, 92.7%) and bla_SHV (8/55, 14.5%) ESBLs, and bla_GES (2/55, 3.6%) carbapenemase-encoding resistance determinants. Genes conferring quinolone resistance were detected at all sites, except in the inflow sewage and aeration tanks. Quinolone resistance was primarily attributed to amino acid substitutions in the QRDR of GyrA (47%) or to the presence of PMQR (aac-(6')-Ib-cr, oqxAB, qnrS, and/or qnrB; 52.9%) determinants. Ciprofloxacin residue was absent only from URW. Our results have shown strains carrying ESBL genes, PMQR determinants, and mutations in the gyrA QRDR genes mainly in hospital effluent, URW, and DRW samples. Antimicrobial use, and the inefficient removal of MDR bacteria and antibiotic residue during sewage treatment, may contribute to the emergence and spreading of resistance in the environment, making this a natural reservoir.

Early Infections in Renal Transplant Recipients: Incidence, Risk Factors, and Causative Microorganisms

OBJECTIVES

This study aimed to compare renal transplant recipients with and without infection with respect to demographic and clinical characteristics as well as risk factors; to determine the incidence of posttransplant infections; and to study the antibiotic resistance patterns of bacterial species identified as the causative organisms in posttransplant infections.

MATERIALS AND METHODS

This study included a total of 136 patients undergoing renal transplant in a 4-year period. The patients were categorized into 2 groups. The 2 groups were compared with each other with respect to general clinical and demographic variables and the number and frequency of infectious attacks within a 1-year follow-up, infection type, and antibiotic resistance patterns.

RESULTS

Ninety-two (67.6%) of the subjects were male and 44 (32.4%) were female. A total of 57 (41.9%) patients developed 128 infectious attacks. Urinary tract infections were the most common infections (42.1%). There was a significant correlation between a clinically relevant urinary culture proliferation and postoperative infection rate (P = .002). There was a significant correlation between antimicrobial resistance and the number of infectious attacks (P = .023). There was a significant correlation between the proliferation of Extended Spectrum Beta Lactamase-positive Enterobactericeae species and the number of infectious attacks (P = .000).

CONCLUSIONS

Presence of a clinically relevant proliferation in the preoperative urinary culture, which was identified as a risk factor for infection, increased the number of infectious attacks. Moreover, Extended Spectrum Beta Lactamase-positive Enterobactericeae species increased the number of infections. These 2 principle results should be taken into account in patient management.

CTX-M extended-spectrum β-lactamase-producing Klebsiella spp, Salmonella spp, Shigella spp and Escherichia coli isolates in Iranian hospitals

This study was conducted in Iran in order to assess the distribution of CTX-M type ESBLs producing Enterobacteriaceae. From January 2012 to December 2013, totally 198 E. coli, 139 Klebsiella spp, 54 Salmonella spp and 52 Shigella spp from seven hospitals of six provinces in Iran were screened for resistance to extended-spectrum cephalosporins. After identification and susceptibility testing, isolates presenting multiple-drug resistance (MDR) were evaluated for ESBL production by the disk combination method and by Etest using (cefotaxime and cefotaxime plus clavulanic acid). All isolates were also screened for bla_CTX-M using conventional PCR. A total of 42.92%, 33.81%, 14.81% and 7.69% of the E. coli, Klebsiella spp, Salmonella spp and Shigella spp isolates were MDR, respectively. The presence of CTX-M enzyme among ESBL-producing isolates was 85.18%, 77.7%, 50%, and 66.7%, in E. coli, Klebsiella spp, Salmonella spp and Shigella spp respectively. The overall presence of CTX-M genes in Enterobacteriaceae was 15.4% and among the resistant isolates was 47.6%. This study indicated that resistance to β-lactams mediated by CTX-M enzymes in Iran had similar pattern as in other parts of the world. In order to control the spread of resistance, comprehensive studies and programs are needed.

Bloodstream infections caused by multi-drug resistant Proteus mirabilis: Epidemiology, risk factors and impact of multi-drug resistance

BACKGROUND

The prevalence of antimicrobial co-resistance among ESBL-producing Enterobactereaceae is extremely high in Israel. Multidrug-resistant Proteus mirabilis strains (MDR-PM), resistant to almost all antibiotic classes have been described. The aim was to determine the risk factors for bloodstream infections caused by MDR-PM and clinical outcomes.

METHODS

A retrospective case-control study. Adult patients with PM bacteremia during 7 years were identified retrospectively and their files reviewed for demographics, underlying diseases, Charlson Comorbidity Index, treatment and outcome.

RESULTS

One hundred and eighty patients with PM-bloodstream infection (BSI) were included; 90 cases with MDR-PM and 90 controls with sensitive PM (S-PM). Compared to controls, cases more frequently were from nursing homes, had recurrent hospital admissions in the past year and received antibiotic therapy in the previous 3 months, were bedridden and suffered from peripheral vascular disease and peptic ulcer disease (p < 0.001). Two-thirds of the MDR-PM isolates were ESBL-producers vs 4.4% of S-PM isolates (p < 0.001, OR = 47.6, 95% CI = 15.9-142.6). In-hospital crude mortality rate of patients with MDR-PM BSI was 37.7% vs 23.3% in those with S-PM BSI (p = 0.0359, OR = 2, 95% CI = 1.4-3.81).

CONCLUSIONS

PM bacteremia in elderly and functionally-dependent patients is likely to be caused by nearly pan-resistant PM strains in the institution; 51.8% of the patients received inappropriate empiric antibiotic treatment. The crude mortality rate of patients with MDR-PM BSI was significantly higher than that of patients with S-PM BSI.

Quinolone co-resistance in ESBL- or AmpC-producing Escherichia coli from an Indian urban aquatic environment and their public health implications

Quinolone and β-lactam antibiotics constitute major mainstay of treatment against infections caused by pathogenic Escherichia coli. Presence of E. coli strains expressing co-resistance to both these antibiotic classes in urban aquatic environments which are consistently being used for various anthropogenic activities represents a serious public health concern. From a heterogeneous collection of 61 E. coli strains isolated from the river Yamuna traversing through the National Capital Territory of Delhi (India), those harboring blaCTX-M-15 (n = 10) or blaCMY-42 (n = 2) were investigated for co-resistance to quinolones and the molecular mechanisms thereof. Resistance was primarily attributed to amino acid substitutions in the quinolone resistance-determining regions (QRDRs) of GyrA (S83L ± D87N) and ParC (S80I ± E84K). One of the E. coli strains, viz., IPE, also carried substitutions in GyrB and ParE at positions Ser492→Asn and Ser458→Ala, respectively. The phenotypically susceptible strains nevertheless carried plasmid-mediated quinolone resistance (PMQR) gene, viz., qnrS, which showed co-transfer to the recipient quinolone-sensitive E. coli J53 along with the genes encoding β-lactamases and led to increase in minimal inhibitory concentrations of quinolone antibiotics. To the best of our knowledge, this represents first report of molecular characterization of quinolone co-resistance in E. coli harboring genes for ESBLs or AmpC β-lactamases from a natural aquatic environment of India. The study warrants true appreciation of the potential of urban aquatic environments in the emergence and spread of multi-drug resistance and underscores the need to characterize resistance genetic elements vis-à-vis their public health implications, irrespective of apparent phenotypic resistance.

Molecular epidemiology of quinolon resistant strains of extended spectrum beta-lactamase producing Escherichia coli

Objective:

To determine the clonal relationship of ESBL-producing and quinolone resistant E.coli strains and to investigate the risk factors for infections with these microorganisms.

Methods:

A total of 95 ESBL-producing and quinolone resistant E.coli strains isolated from various clinical specimens of inpatients and outpatients in our hospital were included in the study. Risk factors for infections with ESBL-producing E.coli and demographic data of the patients were obtained from hospital records. The rep-PCR method was used for the determination of the genetic relationship of the strains.

Results:

Of the strains included in the study, 33(34.7%) were isolated from inpatients and 62(65.3%) from outpatients. At least one risk factor has been identified in all patients for infection with ESBL producing E.coli and the mean of the risk factors of patients was 4.2. The most common risk factor was urinary catheter insertion (57.9%). The distribution of the strains in each clone was as fallows: clone A: 9(9.5%), clone B: 10(10.5%), clone C: 38(40%), clone D: 12(12.5%), clone E: 6(6.3%), clone F: 7(7.3%) and clone G 5(5.3%). The clones A, D and C (dominant clone) were isolated from hospital and community acquired infections. Clones E, F and G were identified as nosocomial clones.

Conclusion:

Infections with multidrug resistant bacteria may be related to the hospital although they were isolated from outpatients. Developing a medical record system is vitally important to prevent the occurence and spread of resistant bacterial infections in the community.

A qPCR and multiplex pyrosequencing assay combined with automated data processing for rapid and unambiguous detection of ESBL-producers Enterobacteriaceae

Rapid and specific detection of extended-spectrum β-lactamase-producing (ESBL) bacteria is crucial both for timely antibiotic therapy when treating infected patients as well as for appropriate infection control measures aimed at curbing the spread of ESBL-producing isolates. Whereas a variety of phenotypic methods are currently available for ESBL detection, they remain time consuming and sometimes difficult to interpret while being also affected by a lack of sensitivity and specificity. Considering the longer turnaround time (TAT) of susceptibility testing and culture results, DNA-based ESBL identification would be a valuable surrogate for phenotypic-based methods. Putative ESBL-positive Enterobacteriaceae isolates (n = 330) from clinical specimen were prospectively collected in Bulgaria, Romania and Democratic Republic of Congo and tested in this study. All isolates were assessed for ESBL-production by the E-test method and those giving undetermined ESBL status were re-tested using the combination disk test. A genotypic assay successively combining qPCR detection of blaCTX-M, blaTEM and blaSHV genes with a multiplex pyrosequencing of blaTEM and blaSHV genes was developed in order to detect the most common ESBL-associated TEM and SHV single nucleotides polymorphisms, irrespective of their plasmid and/or chromosomal location. This assay was applied on all Enterobacteriaceae isolates (n = 330). Phenotypic and genotypic results matched in 324/330 (98.2%). Accordingly, real-time PCR combined with multiplex pyrosequencing appears to be a reliable and easy-to-perform assay with high-throughput identification and fast TAT (~5 h).

Pulmonary Pneumatocele in a Pneumonia Patient Infected with Extended-Spectrum β-Lactamase Producing Proteus mirabilis

Pulmonary pneumatoceles are air-filled thin-walled spaces within the lung and are rare in adult cases of pneumonia. We report the case of a 74-year-old male who was admitted with a cough and sputum production. He had been treated with oral dexamethasone since a brain tumorectomy 6 months prior. Contrast-enhanced computed tomography (CT) of the chest revealed a large pneumatocele in the right middle lobe and peripheral pneumonic consolidation. Bronchoalveolar lavage was performed; cultures identified extended-spectrum β-lactamase (ESBL) producing Proteus mirabilis. A 4-week course of intravenous ertapenem was administered, and the pneumatocele with pneumonia resolved on follow-up chest CT. To the best of our knowledge, this is the first reported case of pulmonary pneumatocele caused by ESBL-producing P. mirabilis associated with pneumonia.

In Vitro Activity of Oral Cephalosporins (Cefprozil and Cefixime) Against Ciprofloxacin-Resistant Enterobacteriaceae from Community-Acquired Urinary-Tract Infections

INTRODUCTION

The global emergence of pathogens of urinary-tract infections resistant to ciprofloxacin or producing extended-spectrum β-lactamases (ESBL) led us to investigate the activity of older antimicrobials such as cefprozil and cefixime against a recent broad collection of urine enterobacteria from 2012 and 2013.

METHODS

Minimum inhibitory concentrations and minimum bactericidal concentrations of cefprozil, cefixime and ciprofloxacin were determined against 293 Escherichia coli (40 ESBL producers), 54 Klebsiella pneumoniae (10 ESBL producers) and 53 Proteus mirabilis isolates.

RESULTS

Cefprozil was more active than ciprofloxacin against non-ESBL-producing E. coli (93.7% vs 80.2%, p < 0.0001); this was not the case for cefixime (85.7% vs 80.2%, p: 0.125). Overall, cefprozil and cefixime inhibited 80-90% of ciprofloxacin-resistant isolates of all studied species. However, they were active against less than 20% of ESBL-producing isolates.

CONCLUSION

Results suggest that cefprozil and cefixime remain a good therapeutic alternative against urine enterobacteria particularly in case of ciprofloxacin-resistant pathogens. Their activity against ESBL-producing pathogens is limited.

Interactions of Klebsiella pneumoniae with the innate immune system vary in relation to clone and resistance phenotype

Apart from inadequate antimicrobial treatment, specific virulence factors contribute to the high attributable mortality of infections caused by multidrug-resistant (MDR) Klebsiella pneumoniae. We explored the roles of MDR and clones as virulence determinants of K. pneumoniae and their interaction with innate immunity. Twenty isolates were studied and characterized by resistance phenotype and multilocus sequence type (MLST). Human peripheral blood mononuclear cells (PBMCs) were stimulated for the production of proinflammatory cytokines by live and heat-killed isolates and plasmid DNA; modulation by cellular pathway inhibitors was explored. Survival of 30 mice was recorded after intraperitoneal challenge with susceptible and K. pneumoniae carbapenemase (KPC)-producing isolates. Splenocytes of mice were stimulated for the production of pro- and anti-inflammatory cytokines. Isolates were divided into different patterns of production of tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β) poststimulation in relation to both the MLST clone and resistance phenotype. The sequence type 383 (ST383) clone producing Verona integron-encoded metallo-β-lactamase (VIM) stimulated high production of both TNF-α and IL-1β. Clone ST17 producing KPC elicited low TNF-α production; this was reversed by Toll-like receptor 9 (TLR9) antagonists, indicating an effect of plasmid DNA. This isolate was linked with early death of mice compared to high-TNF-α-producing isolates. We conclude that KPC-producing isolates seem to be highly virulent in a low-TNF-α-release environment, suggesting an immunoparalysis induction mechanism. KPC plasmids may directly contribute to the immune system stimulation.

Pathogenic and commensal Escherichia coli from irrigation water show potential in transmission of extended spectrum and AmpC β-lactamases determinants to isolates from lettuce

There are few studies on the presence of extended-spectrum β-lactamases and AmpC β-lactamases (ESBL/AmpC) in bacteria that contaminate vegetables. The role of the production environment in ESBL/AmpC gene transmission is poorly understood. The occurrence of ESBL/AmpC in Escherichia coli (n = 46) from lettuce and irrigation water and the role of irrigation water in the transmission of resistant E. coli were studied. The presence of ESBL/AmpC, genetic similarity and phylogeny were typed using genotypic and phenotypic techniques. The frequency of β-lactamase gene transfer was studied in vitro. ESBLs/AmpC were detected in 35 isolates (76%). Fourteen isolates (30%) produced both ESBLs/AmpC. Prevalence was highest in E. coli from lettuce (90%). Twenty-two isolates (48%) were multi-resistant with between two and five ESBL/AmpC genes. The major ESBL determinant was the CTX-M type (34 isolates). DHA (33% of isolates) were the dominant AmpC β lactamases. There was a high conjugation efficiency among the isolates, ranging from 3.5 × 10(-2) to 1 × 10(-2)  ± 1.4 × 10(-1) transconjugants per recipient. Water isolates showed a significantly higher conjugation frequency than those from lettuce. A high degree of genetic relatedness between E. coli from irrigation water and lettuce indicated possible common ancestry and pathway of transmission.

Incidence of Urinary Tract Infection Following Transrectal Ultrasound Guided Prostate Biopsy at a Tertiary-Care Medical Center in Lebanon

Objective:

To determine the incidence of urinary tract infections (UTIs) following transrectal ultrasound guided needle biopsy of the prostate (TRUBP) and the bacteriology of these infections.

Design:

Retrospective evaluation of the charts and records of all patients who underwent TRUBP between June 1, 2002, and August 31, 2003.

Setting:

American University of Beirut Medical Center, a tertiary-care center in Lebanon.

Patients:

Two hundred seven patients underwent TRUBP. All received prophylactic antibiotics. One hundred twenty (58%) received ciprofloxacin alone, whereas 87 (42%) received both ciprofloxacin and gentamicin. Sixty-one patients (29.5%) had an enema prior to the procedure, whereas 146 (70.5%) did not.

Results:

Thirteen patients (6.3%) were admitted with UTI. All had rigors and fever on admission. Symptoms appeared at a mean of 2.7 days and the mean hospital stay was 9.2 days. The mean duration of antibiotic treatment was 23.2 days. Ten (77%) of the patients had positive bacteriology. Urine cultures were positive in 8 (61.5%) of the patients and blood cultures in 6 (46.2%). All positive cultures grew Escherichia coli resistant to ciprofloxacin, with 5 isolates producing extended-spectrum beta-lactamases.

Conclusions:

TRUBP continues to be associated with significant infectious complications, especially UTI. Given the increasing incidence of antibiotic resistance mainly among the Enterobacteriaceae, antimicrobial prophylaxis practices should be reevaluated and the universal administration of quinolones alone or in combination with aminoglycosides should be reconsidered.

TEM and SHV Genes in Klebsiella pneumoniae Isolated from Cockroaches and Their Antimicrobial Resistance Pattern

Objectives

Klebsiella pneumoniae is a gram-negative rod bacterium, a known cause of community-acquired bacterial pneumonia and is an important hospital-acquired pathogen that causes severe morbidity and mortality. The aim of this study was to identify the TEM and SHV genes in K. pneumoniae isolated from cockroaches obtained from hospitals.

Methods

In this study, 250 cockroaches were collected from different hospitals in the province of Chaharmahal Va Bakhtiari, which is located in southwest Iran. The samples were examined for the presence of K. pneumoniae by plating onto a combination of culture media, and the antimicrobial susceptibility patterns of isolated K. pneumoniae from samples were evaluated using the disk diffusion test. In addition, from the culture, genomic bacterial DNA was extracted, and sequence-specific targets (TEM and SHV genes) were amplified using the polymerase chain reaction (PCR) method.

Results

Out of 250 cockroach samples collected from various hospitals, 179 samples (71.60%) were positive for K. pneumoniae. PCR reaction was performed using specific oligonucleotide primers (TEM-F, TEM-R and SHV-F, SHV-R) for the amplification of each gene, and amplified products were visualized on 1% agarose gel electrophoresis. Of all the specimens amplified by PCR in this research, 32 samples (17.87%) were positive for TEM and 15 samples (8.37%) were positive for SHV.

Conclusion

Detection of TEM and SHV genes using molecular methods and their pattern of antimicrobial resistance can provide useful information about the epidemiology of and risk factors associated with K. pneumoniae infection.

Extended-Spectrum β-Lactamase-Producing and Third-Generation Cephalosporin-Resistant Enterobacteriaceae in Children: Trends in the United States, 1999-2011

BACKGROUND

Enterobacteriaceae infections resistant to extended-spectrum β-lactams are an emerging problem in children. We used a large database of clinical isolates to describe the national epidemiology of extended-spectrum β-lactamase (ESBL)-producing and third-generation cephalosporin-resistant (G3CR) Enterobacteriaceae.

METHODS

Antimicrobial susceptibilities of Klebsiella pneumoniae, Escherichia coli, and Proteus mirabilis reported to ∼300 laboratories participating in The Surveillance Network (TSN) between January 1999 and December 2011 were used to phenotypically identify G3CR and ESBL isolates cultured from patients <18 years. Bi-annual trends in the prevalence of each phenotype were stratified by species, patient location, culture site, age, and region. Children of age 0-1 years were excluded from analysis as data were only available from 2010 onwards.

RESULTS

Out of 368,398 pediatric isolates, 1.97% (7255) were identified as G3CR, and 0.47% (1734) as ESBL producers. The prevalence of both phenotypes increased, respectively, from 1.39% and 0.28% in 1999-2001 to 3% and 0.92% in 2010-2011. Trends were significant across all demographic and age groups, including outpatients, with the highest proportion of isolates in the 1-5-year-old age group. The majority of G3CR and ESBL isolates were E. coli (67.8% and 65.2%, respectively). Among ESBLs, resistance to ≥3 antibiotic classes was 74%. The lower regional prevalence of ESBL-producing bacteria in the upper Midwest relative to the rest of the country is consistent with recent local data.

CONCLUSIONS

Rates of G3CR and ESBL infections in children are increasing in both inpatient and ambulatory settings nationally. The identification of host factors and exposures leading to infection in children is essential.

Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae Infections in Children: A Two-Center Case-Case-Control Study of Risk Factors and Outcomes in Chicago, Illinois

BACKGROUND

Extended-spectrum β-lactamase (ESBL)-producing Enterobacteriaceae infections are an emerging problem in children. We sought to identify risk factors and describe outcomes associated with pediatric ESBL-producing bacterial infections at 2 hospitals in Chicago, IL from 2008 to 2011.

METHODS

A case-case-control study of children aged 0-17 years was conducted. Cases of Escherichia coli, Klebsiella, and Proteus spp. ESBL-producing bacterial infections (n = 30) were compared to uninfected controls and in parallel, cases of non-ESBL-producing bacterial infections (n = 30) were compared to uninfected controls (n = 60). We then qualitatively compared these results.

RESULTS

Median age of cases was 1.06 years; 62% of isolates were from urine, and 60% were E. coli. By multivariable analysis, ESBL cases were 5.7 and 3.3 times more likely to have gastrointestinal (P = .001; 95% confidence interval [CI] 1.9-17.0) and neurologic (P = .001; 95% CI 1.1-3.7) comorbidities, respectively, than controls; non-ESBL cases were also more likely to have gastrointestinal comorbidities than controls (P = .014; odds ratio 3.6; 95% CI 1.2-10.1). Study period prevalence remained stable (1.7%). Most (60%) infections occurred in the intensive care unit; however, 30% of children presented in the outpatient setting. Seventy-seven percent of isolates were multidrug resistant (ie, resistant to ≥3 antibiotic classes). Recurrence of infection occurred in 17% of ESBL cases. Crude mortality rates (7%) did not differ between cases and controls.

CONCLUSIONS

The incidence of pediatric infection due to ESBL-positive Enterobacteriaceae was stable at 2 large tertiary-care medical centers over a 4-year period. Multidrug resistance in pediatric ESBL isolates is common. Risk factors for infection due to ESBL-producing bacteria include neurologic medical conditions.

Prevalence of Extended Spectrum β-lactamase-Producing Klebsiella pneumoniae in Clinical Isolates

Background:

Extended spectrum β-lactamase (ESBL) are gram-negative bacteria that produce the enzyme, β-lactamase, which can break down commonly used antibiotics, such as penicillin and cephalosporins, making infections with ESBL producing bacteria more difficult to treat. Extended spectrum β-lactamase-producing Klebsiella pneumoniae were first reported in 1983 from Germany, and since then a steady increase in resistance against cephalosporins has been seen causing health problems.

Objectives:

The aim of this study was to determine the prevalence of ESBL in strains of K. pneumoniae isolated from different clinical samples.

Patients and Methods:

One hundred and thirty isolates of K. pneumoniae were isolated from different clinical specimens from King Khalid hospital, Hafr Elbatin, Kingdom Saudi Arabia. These isolates were then characterized, tested for antimicrobial susceptibility and screened for ESBL production by the MicroScan WalkAway-96 SI System. Extended spectrum β-lactamase production was confirmed by the phenotypic confirmatory disc diffusion test (PCDDT) and the double disc synergy test (DDST).

Results:

Overall, 76.9% (100) of the isolates were resistant to cefuroxime, cefepime and cefazolin, 69.23% (90) were resistant to cefotaxime, and 46.15% (60) were resistant to cefoxitin. Extended spectrum β-lactamase was detected in 53.8% (70) of K. pneumoniae as detected by the MicroScan “WalkAway-96” SI System and 50.07% (66) by PCDDT and 46.15% (60) by DDST. All K. pneumoniae isolates were resistant to ampicillin followed by both piperacillin and mezlocillin 92.30% (120). K.pneumoniae isolates showed high sensitivity to imipenem (15.38%) (20), followed by ertapenem, tetracycline, tigecycline pipracilline/tazobactam and amikacin (23.07%) (30).

Conclusions:

Our study showed that the prevalence of ESBL-producing K. pneumoniae at King Khalid Hospital was significantly high. Routine detection of ESBL-producing microorganisms is required by each of the laboratory standard detection methods to control the spread of these infections and allow a proper therapeutic strategy. For detection, the phenotypic confirmatory disc diffusion test is simple, sensitive and cost effective. However, there is a need for larger scale drug susceptibility surveillance.

Piperacillin/tazobactam vs. cefoperazone/sulbactam in adult low-risk febrile neutropenia cases

AIM

The aim of this study was to compare the efficacy of piperacillin/tazobactam (P/T) and cefoperazone/sulbactam (C/S) in the empirical treatment of adult neutropenic fever.

METHODS

Data and outcomes of low-risk adult cases with neutropenic fever and treated with P/T (4.5 g q6h) or C/S (2 g q8h) between 2005 and 2011 June were extracted from our database. Risk evaluation was made according to criteria of Multinational Association for Supportive Care in Cancer (MASCC) and a score of ≥ 21 was considered as low risk. Data were collected prospectively by daily visits and evaluated retrospectively. Primary outcome was - fever defervescence at 72 h in combination with success without modification (referring to episodes where the patient recovered from fever with disappearance of signs of infection without modification to initial empirical treatment). All-cause mortality referred to death resulting from a documented or presumed infection or unidentified reason during the treatment and 30-day follow-up period.

RESULTS

A total of 172 patients (113 cases P/T and 59 cases C/S) fulfilled the study inclusion criteria. Persistent response in P/T arm was 73.5%, whereas it was 64.5% in C/S arm (p > 0.05). Rates of any modification were also similar in both treatment arms. All-cause mortality during the treatment and 30-day follow-up period was not significantly different (P/T: 4/113 vs. C/S: 2/59, p > 0.05). There was no severe adverse effect requiring antibiotic cessation in both cohorts.

CONCLUSION

In conclusion, our data suggest that C/S may be a safe alternative to P/T in the empirical treatment of adult low-risk febrile neutropenia cases.

Evaluation of matrix-assisted laser desorption ionization-time of flight mass spectrometry for rapid detection of β-lactam resistance in Enterobacteriaceae derived from blood cultures

The identification of pathogens directly from blood cultures by matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) can be a valuable tool for improving the treatment of patients with sepsis and bacteremia. However, the increasing incidence of multidrug-resistant Gram-negative bacteria makes it difficult to predict resistance patterns based only on pathogen identification. Most therapy regimens for sepsis caused by Gram-negative rods consist of at least one β-lactam antibiotic. Thus, it would be of great benefit to have an early marker of resistance against these drugs. In the current study, we tested 100 consecutive blood cultures containing Enterobacteriaceae for resistance against 3rd-generation cephalosporins in a MALDI-TOF MS β-lactamase assay. Escherichia coli was also tested for resistance against aminopenicillins. The results of the β-lactamase assay were compared with those of conventional methods. The assay permitted discrimination between E. coli strains that were resistant or susceptible to aminopenicillins with a sensitivity and a specificity of 100%. The same was true for resistance to 3rd-generation cephalosporins in Enterobacteriaceae that constitutively produced class C β-lactamases. Discrimination was more difficult in species expressing class A β-lactamases, as these enzymes can generate false-positive results. Thus, the sensitivity and specificity for this group were 100% and 91.5%, respectively. The test permitted the prediction of resistance within 2.5 h after the blood culture was flagged as positive.

Comprehensive analysis of ß-lactam antibiotics including penicillins, cephalosporins, and carbapenems in poultry muscle using liquid chromatography coupled to tandem mass spectrometry

A comprehensive method for the quantitative residue analysis of trace levels of 22 ß-lactam antibiotics, including penicillins, cephalosporins, and carbapenems, in poultry muscle by liquid chromatography in combination with tandem mass spectrometric detection is reported. The samples analyzed for ß-lactam residues are hydrolyzed using piperidine in order to improve compound stability and to include the total residue content of the cephalosporin ceftifour. The reaction procedure was optimized using a full experimental design. Following detailed isotope labeling, tandem mass spectrometry studies and exact mass measurements using high-resolution mass spectrometry reaction schemes could be proposed for all ß-lactams studied. The main reaction occurring is the hydrolysis of the ß-lactam ring under formation of the piperidine substituted amide. For some ß-lactams, multiple isobaric hydrolysis reaction products are obtained, in accordance with expectations, but this did not hamper quantitative analysis. The final method was fully validated as a quantitative confirmatory residue analysis method according to Commission Decision 2002/657/EC and showed satisfactory quantitative performance for all compounds with trueness between 80 and 110% and within-laboratory reproducibility below 22% at target level, except for biapenem. For biapenem, the method proved to be suitable for qualitative analysis only.

Extended spectrum beta lactamase peritonitis: Time for innovation?

Extended spectrum beta lactamase (ESBL) producing bacteria that are capable of hydrolyzing even third generation cephalosporin are emerging as a potent threat. We report a seven-year-old child on continuous ambulatory peritoneal dialysis, who developed ESBL producing Klebsiella pneumoniae peritonitis. The bacterium was resistant to the usual intraperitoneal antibiotics. We successfully treated the child with intravenous meropenem along with oral cotrimoxazole. The case highlights the menace of ESBL peritonitis, as also a need for the development of guidelines for such a scenario, which is becoming increasingly common in India.

A step towards the discrimination of beta-lactamase-producing clinical isolates of Enterobacteriaceae and Pseudomonas aeruginosa by MALDI-TOF mass spectrometry

Background

Matrix-Assisted Laser-Desorption/Ionization Time of Flight Mass Spectrometry (MALDI-TOF MS) has already proven to be a powerful tool for species identification in microbiological laboratories. As adequate and rapid screening methods for antibiotic resistance are crucially needed, the present study investigated the discrimination potential of MALDI-TOF MS among extended-spectrum-beta-lactamase (ESBL) or metallo-beta-lactamases- (MBL) producing and the nonproducing strains of Escherichia coli (n=19), Klebsiella pneumoniae (n=19), and Pseudomonas aeruginosa (n=38), respectively.

Material/Methods

We used a MALDI-TOF MS protocol, usually applied for species identification, in order to integrate a screening method for beta-lactamases into the routine species identification workflow. The acquired spectra were analyzed by visual inspection, statistical similarity analysis and support vector machine (SVM) classification algorithms.

Results

Neither visual inspection nor mathematical similarity analysis allowed discrimination between spectra of beta-lactamase-producing and the nonproducing strains, but classification within a species by SVM-based algorithms could achieve a correct classification rate of up to 70%.

Conclusions

This shows that MALDI-TOF MS has definite potential to discriminate antibiotic-resistant strains due to ESBL and MBL production from nonproducing strains, but this performance is not yet sufficiently reliable for routine microbiological diagnostics.

Prevalence of ESBL-Producing Klebsiella pneumoniae Isolates in Tertiary Care Hospital

Extended-spectrum β lactamases (ESBLs) continue to be a major challenge in clinical setups world over, conferring resistance to the expanded-spectrum cephalosporins. An attempt was made to study the prevalence of ESBL-producing Klebsiella pneumoniae clinical isolates in a tertiary care hospital in Kurnool. A total of hundred collected isolates of Klebsiella pneumoniae was studied for their susceptibility patterns to various antibiotics and detection of ESBL producers by double disc synergy test (DDST) and phenotypic confirmatory disc diffusion test (PCDDT). Of the 100 isolates tested for their antibiogram, 61% isolates have shown susceptibility to 3rd-generation cepholosporins and 39% were resistant. Amoxycillin showed the highest percentage of resistance followed by tetracyclins and cotrimoxazole. Among 39 resistant isolates of Klebsiella pneumoniae, 17 were ESBL producers detected by DDST and PCDDT. ESBL producers were more in the hospital isolates (28%) compared to community isolates (6%). Maximum percentage of ESBL producers were noticed from blood sample with 57.14%. In the present study, a large number of isolates were found to be multidrug resistant and ESBL producers. PCDDT was found to be better than DDST in the detection of ESBLs. Continued monitoring of drug resistance is necessary in clinical settings for proper disease management.

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.