Multicenter, Prospective Validation of a Phenotypic Algorithm to Guide Carbapenemase Testing in Carbapenem-Resistant Pseudomonas aeruginosa using the ERACE-PA Global Surveillance Program

Abstract Background Carbapenemase-producing, carbapenem-resistant Pseudomonas aeruginosa (CP-CRPA) are a global challenge. However, detection efforts can be laborious because numerous mechanisms produce carbapenem resistance. An MIC based algorithm (imipenem or meropenem-resistant plus ceftazidime-non-susceptible plus cefepime-non-susceptible) was proposed to identify isolates most likely to harbor a carbapenemase; however, prospective validation in geographies displaying genotypic diversity and varied carbapenemase prevalence is warranted. Methods CRPA were collected during the ERACE-PA global surveillance program from 17 sites in 12 countries. Isolates underwent susceptibility testing following local standards to ceftazidime, cefepime, and ceftolozane/tazobactam. Isolates underwent initial phenotypic carbapenemase screening followed by molecular testing if positive. The primary algorithm criteria were applied and results compared to phenotypic carbapenemase results to assess the performance of the algorithm. A secondary criteria of (the algorithm criteria or imipenem or meropenem-resistant plus ceftolozane/tazobactam-non-susceptible) was assessed. Results 807 CRPA were assessed and 464 isolates met the algorithm criteria described above. Overall, testing was reduced by 43% compared with testing all CRPA. Carbapenemase-positive isolates missed by the algorithm were largely driven by GES. Addition of the criteria of imipenem or meropenem-resistant plus ceftolozane/tazobactam-non-susceptible decreased the number of CP-CRPA missed by the algorithm (21 versus 40 isolates, respectively) still reducing number of isolates tested by 39%. Conclusions Application of the initial algorithm (imipenem or meropenem-resistant plus ceftazidime-non-susceptible plus cefepime-non-susceptible) performed well in a global cohort with 33% phenotypically carbapenemase-positive isolates. Addition of imipenem or meropenem-resistant plus ceftolozane/tazobactam-non-susceptible reduced the number of phenotypically carbapenemase-positive isolates missed and may be useful in areas with a prominence of GES.

Download Full-text

Nonsusceptibility to Ceftazidime or Cefepime Can Predict Carbapenemase-Production Among Carbapenem-Resistant Pseudomonas aeruginosaa

Infection Control and Hospital Epidemiology ◽

10.1017/ice.2020.934 ◽

2020 ◽

Vol 41 (S1) ◽

pp. s330-s331

Author(s):

Snigdha Vallabhaneni ◽

Jennifer Huang ◽

Julian Grass ◽

Sarah Malik ◽

Amelia Bhatnagar ◽

...

Keyword(s):

Drug Combination ◽

Susceptibility Testing ◽

Clinical Laboratory ◽

Carbapenem Resistance ◽

The United States ◽

Population Based ◽

Molecular Testing ◽

Carbapenem Resistant ◽

Clinical Laboratories ◽

Break Points

Background: In the United States, carbapenemases are rarely the cause of carbapenem resistance in Pseudomonas aeruginosa. Detection of carbapenemase production (CP) in carbapenem-resistant P. aeruginosa (CRPA) is critical for preventing its spread, but testing of many isolates is required to detect a single CP-CRPA. The CDC evaluates CRPA for CP through (1) the Antibiotic Resistance Laboratory Network (ARLN), in which CRPA are submitted from participating clinical laboratories to public health laboratories for carbapenemase testing and antimicrobial susceptibility testing (AST) and (2) laboratory and population-based surveillance for CRPA in 8 sites through the Emerging Infection Program (EIP). Objective: We used data from ARLN and EIP to identify AST phenotypes that can help detect CP-CRPA. Methods: We defined CRPA as P. aeruginosa resistant to meropenem, imipenem, or doripenem, and we defined CP-CRPA as CRPA with molecular identification of carbapenemase genes (blaKPC, blaIMP, blaNDM, or blaVIM). We applied CLSI break points to 2018 ARLN CRPA AST data to categorize isolates as resistant, intermediate, or susceptible, and we evaluated the sensitivity and specificity of AST phenotypes to detect CP among CRPA; isolates that were intermediate or resistant were called nonsusceptible. Using EIP data, we assessed the proportion of isolates tested for a given drug in clinical laboratories, and we applied definitions to evaluate performance and number needed to test to identify a CP-CRPA. Results: Only 203 of 6,444 of CRPA isolates (3%) tested through AR Lab Network were CP-CRPA harboring blaVIM (n = 123), blaKPC (n = 53), blaIMP (n = 16), or blaNDM (n = 13) genes. Definitions with the best performance were resistant to ≥1 carbapenem AND were (1) nonsusceptible to ceftazidime (sensitivity, 93%; specificity, 61%) (Table 1) or (2) nonsusceptible to cefepime (sensitivity, 83%; specificity, 53%). Most isolates not identified by definition 2 were sequence type 111 from a single-state blaVIM CP-CRPA outbreak. Among 4,209 CRPA isolates identified through EIP, 80% had clinical laboratory AST data for ceftazidime and 96% had clinical laboratory AST data for cefepime. Of 967 CRPA isolates that underwent molecular testing at the CDC, 7 were CP-CRPA; both definitions would have detected all 7. Based on EIP data, the number needed to test to identify 1 CP-CRPA would decrease from 135 to 42 for definition 1 and to 50 using definition 2. Conclusions: AST-based definitions using carbapenem resistance combined with ceftazidime or cefepime nonsusceptibility would rarely miss a CP-CRPA and would reduce the number needed to test to identify CP-CRPA by >60%. These definitions could be considered for use in laboratories to decrease the testing burden to detect CP-CRPA.Funding: NoneDisclosures: In the presentation we will discuss the drug combination aztreonam-avibactam and acknowledge that this drug combination is not currently FDA approved.

Download Full-text

Development and Application of a Pragmatic Algorithm to Guide Definitive Carbapenemase Testing to Identify Carbapenemase-Producing Pseudomonas aeruginosa

Antibiotics ◽

10.3390/antibiotics9110738 ◽

2020 ◽

Vol 9 (11) ◽

pp. 738

Author(s):

Christian M. Gill ◽

Tomefa E. Asempa ◽

David P. Nicolau

Keyword(s):

Pseudomonas Aeruginosa ◽

Minimum Inhibitory Concentration ◽

Inhibitory Concentration ◽

Carbapenem Resistance ◽

Surveillance Program ◽

Broth Microdilution ◽

Wild Type ◽

Confirmatory Testing ◽

Carbapenem Resistant

A minimum inhibitory concentration (MIC) derived algorithm, predictive of carbapenemase production, was developed using a challenge set (n = 92) of Pseudomonas aeruginosa (PA), including carbapenemase-producing (CP), cephalosporinase and/or efflux/porin mutation, and wild-type isolates. Broth microdilution MICs to clinically relevant anti-pseudomonal agents were utilized. The algorithm was applied to 1209 clinical PA isolates from a US surveillance program. Confirmatory genotypic (Xpert® Carba-R assay) and phenotypic (mCIM/eCIM) testing for carbapenemases was conducted on algorithm-derived isolates. With the algorithm, carbapenem resistance alone resulted in poor specificity to identify CP-PA (54%) within the challenge set of isolates. Inclusion of cefepime, ceftazidime, and piperacillin/tazobactam non-susceptibility resulted in a specificity of 66%. Ceftolozane/tazobactam resistance further improved specificity (89%). Of the 1209 isolates, 116 met criteria (carbapenem-resistant and non-susceptibility to cefepime, ceftazidime, and piperacillin/tazobactam) for confirmatory testing. Carba-R and mCIM/eCIM identified five (all blaVIM-positive) and seven carbapenemase-producing isolates, respectively. This MIC algorithm combined with genotypic/phenotypic carbapenemase testing is a pragmatic and streamlined approach to identify CP-PA.

Download Full-text

Phenotypic characterization and colistin susceptibilities of carbapenem-resistant of Pseudomonas aeruginosa and Acinetobacter spp.

The Journal of Infection in Developing Countries ◽

10.3855/jidc.2924 ◽

2013 ◽

Vol 7 (11) ◽

pp. 880-887 ◽

Cited By ~ 15

Author(s):

Srujana Mohanty ◽

Vijeta Maurya ◽

Rajni Gaind ◽

Monorama Deb

Keyword(s):

Pseudomonas Aeruginosa ◽

Susceptibility Testing ◽

Carbapenem Resistance ◽

Multidrug Resistant ◽

Resistance Mechanisms ◽

Phenotypic Characterization ◽

Antibiotic Susceptibility Testing ◽

Colistin Resistance ◽

Carbapenem Resistant ◽

Acinetobacter Spp

Introduction: Pseudomonas aeruginosa and Acinetobcter spp. are important nosocomial pathogens and carbapenem resistance is an emerging threat. Therapeutic options for infections with these isolates include colistin. This study was conducted to determine the prevalence of carbapenem resistance in P. aeruginosa and Acinetobacter spp. bloodstream isolates, phenotypically characterize the resistance mechanisms and evaluate the invitro activity of colistin. Methodology: Consecutive 145 (95 P.aeruginosa and 50 Acinetobacter spp.) non-repeat isolates were included. Antibiotic susceptibility testing was performed per CLSI guidelines. MIC for carbapenems and colistin was performed using Etest. Isolates showing reduced susceptibility or resistance to the carbapenems were tested for metallo-β-lactamase (MBL) production using imipenem-EDTA combined disk and MBL Etest. Results: Carbapenem resistance was observed in 40% P. aeruginosa and 66.0% Acinetobacter spp. Carbapenem-resistant (CA-R) isolates were significantly (p< 0.05) more frequently resistant to the other antibiotics than carbapenem-susceptible isolates. Approximately half of the CA-R strains were multidrug-resistant, and 3.1-5.5% were resistant to all antibiotics tested. MBL was found in 76.3% and 69.7% of the P. aeruginosa and Acinetobacter spp., respectively. Colistin resistance was observed in three (6.0%) Acinetobacter isolates and eight (8.4%) P. aeruginosa. MIC50 for carbapenems were two to four times higher for MBL-positive compared to MBL-negative isolates, but no difference was seen in MIC for colistin. Conclusion: Carbapenem resistance was observed to be mediated by MBL in a considerable number of isolates. Colistin is an alternative for infections caused by CA-R isolates; however, MIC testing should be performed whenever clinical use of colistin is considered.

Download Full-text

A comparative evaluation of two chromogenic media for surveillance of carbapenem-resistant Enterobacterales with non-carbapenemase-producing or carbapenemase-producing strains other than blaKPC: blaGES-5, blaNDM-1 or blaVIM-2

Journal of Laboratory Medicine ◽

10.1515/labmed-2018-0139 ◽

2019 ◽

Vol 43 (3) ◽

pp. 173-176

Author(s):

Chang-Hun Park

Keyword(s):

Rapid Detection ◽

Comparative Evaluation ◽

Susceptibility Testing ◽

Rapid Identification ◽

Surveillance Program ◽

Contact Precaution ◽

Chain Reaction ◽

Carbapenem Resistant ◽

Control And Prevention ◽

Polymerase Chain

Abstract Background Infections caused by carbapenem-resistant Enterobacterales (CREs) are an emerging problem associated with high rates of morbidity and mortality. CREs are divided into two categories (carbapenemase-producing [CP] CRE and non-CP CRE). The most prevalent carbapenemase produced by Enterobacterales is Klebsiella pneumoniae carbapenemase (KPC) in Korea. Rapid identification of CREs is clinically important in infection control precaution. We compared the performance of two chromogenic media (chromID CARBA agar and CHROMagar KPC agar) for non-CP CREs or CP CREs with blaGES-5, blaNDM-1 or blaVIM-2 in a Korean hospital. Methods The study was carried out during a 3-month period from April to June 2017 during the surveillance program for CRE colonization. Antimicrobial susceptibility testing (AST) and polymerase chain reaction (PCR) were performed at the Korean Centers for Disease Control and Prevention. Results A total of 45 rectal swabs from 42 hospitalized patients were examined. Sensitivity of both chromID CARBA and CHROMagar KPC were 100% for CP CREs; and 50% and 100% for non-CP CREs, respectively. Specificity of chromID CARBA and CHROMagar KPC were 89.2% and 70.3% for CP CRE, respectively; and 76.9% and 66.7% for non-CP CRE, respectively. Conclusions The CHROMagar KPC is useful to monitor non-CP and CP CREs. The chromID CARBA is efficient for rapid detection of CP CREs requiring high contact precaution.

Download Full-text

Prevalence of metallo-β-lactamase genes among Pseudomonas aeruginosa isolated from various clinical samples in China

Journal of Laboratory Medicine ◽

10.1515/labmed-2019-0162 ◽

2020 ◽

Vol 0 (0) ◽

Author(s):

Wei Wang ◽

Xiaoya Wang

Keyword(s):

Pseudomonas Aeruginosa ◽

Antibiotic Susceptibility ◽

Ethylenediaminetetraacetic Acid ◽

Carbapenem Resistance ◽

Opportunistic Pathogen ◽

Detection Methods ◽

Clinical Samples ◽

Routine Practice ◽

Carbapenem Resistant ◽

High Prevalence

AbstractBackgroundPseudomonas aeruginosa is an opportunistic pathogen which is associated with nosocomial infections and causes various diseases including urinary tract infection, pneumonia, soft-tissue infection and sepsis. The emergence of P. aeruginosa-acquired metallo-β-lactamase (MBL) is most worrisome and poses a serious threat during treatment and infection control. The objective of this study was to identify antibiotic susceptibility, phenotypic detection of MBL production and to determine the prevalence of MBL genes in carbapenem-resistant P. aeruginosa isolated from different clinical samples.MethodsA total of 329 non-duplicate P. aeruginosa isolated from various clinical samples from two hospitals in China between September 2017 and March 2019 were included in this study. Phenotypic detection of MBL was performed by the combined detection method using imipenem and imipenem-ethylenediaminetetraacetic acid (EDTA) discs. MBL-encoding genes including blaVIM-1, blaVIM-2, blaIMP-1, blaIMP-2, blaSPM-1, blaSIM, blaNDM-1 and blaGIM were detected by polymerase chain reaction (PCR).ResultsOf the 329 P. aeruginosa, majority of the isolates were resistant to imipenem (77.5%) followed by meropenem (64.7%). Of the 270 P. aeruginosa isolates tested, 149 (55.2%) isolates were found to be positive for MBL detection. Of the different samples, 57.8% (n = 26) of P. aeruginosa isolated from blood were found to be positive for MBL production. Of the various MBL genes, blaIMP-1 (28.2%) was the most predominant gene detected followed by blaVIM-2 (18.8%), blaVIM-1 (16.1%), blaNDM-1 (9.4%), blaIMP-2 (6.7%), blaSIM (6.0%), blaSPM-1 (4.0%) and blaGIM (1.3%) genes.ConclusionsThe high resistance of P. aeruginosa toward imipenem and meropenem and the high prevalence of blaIMP-1 and blaVIM-2 set the alarm on the increasing, perhaps the increased, carbapenem resistance. In addition to routine antibiotic susceptibility testings, our results emphasize the importance of both the phenotypic and genotypic MBL detection methods in routine practice for early detection of carbapenem resistance and to prevent further dissemination of this resistant pathogen.

Download Full-text

Complete Sequence of pOZ176, a 500-Kilobase IncP-2 Plasmid Encoding IMP-9-Mediated Carbapenem Resistance, from Outbreak Isolate Pseudomonas aeruginosa 96

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00423-13 ◽

2013 ◽

Vol 57 (8) ◽

pp. 3775-3782 ◽

Cited By ~ 48

Author(s):

Jianhui Xiong ◽

David C. Alexander ◽

Jennifer H. Ma ◽

Maxime Déraspe ◽

Donald E. Low ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Carbapenem Resistance ◽

Complete Sequence ◽

Open Reading Frames ◽

Content Type ◽

Conserved Sequence ◽

Carbapenem Resistant ◽

Class 1 ◽

Usage Analysis ◽

Type 3

ABSTRACTPseudomonas aeruginosa96 (PA96) was isolated during a multicenter surveillance study in Guangzhou, China, in 2000. Whole-genome sequencing of this outbreak strain facilitated analysis of its IncP-2 carbapenem-resistant plasmid, pOZ176. The plasmid had a length of 500,839 bp and an average percent G+C content of 57%. Of the 618 predicted open reading frames, 65% encode hypothetical proteins. The pOZ176 backbone is not closely related to any plasmids thus far sequenced, but some similarity to pQBR103 ofPseudomonas fluorescensSBW25 was observed. Two multiresistant class 1 integrons and several insertion sequences were identified. TheblaIMP-9-carrying integron containedaacA4→blaIMP-9→aacA4, flanked upstream by Tn21 tnpMRAand downstream by a completetnioperon of Tn402and amermodule, named Tn6016. The second integron carriedaacA4→catB8a→blaOXA-10and was flanked by Tn1403-liketnpRAand asul1-type 3′ conserved sequence (3′-CS), named Tn6217. Other features include three resistance genes similar to those of Tn5, a tellurite resistance operon, and twopiloperons. The replication and maintenance systems exhibit similarity to a genomic island ofRalstonia solanacearumGM1000. Codon usage analysis suggests the recent acquisition ofblaIMP-9. The origins of the integrons on pOZ176 indicated separate horizontal gene transfer events driven by antibiotic selection. The novel mosaic structure of pOZ176 suggests that it is derived from environmental bacteria.

Download Full-text

Investigation of Metallo-Beta-Lactamases in Carbapenem Resistant Pseudomonas aeruginosa Strains by Phenotypic and Genotypic Methods

Flora the Journal of Infectious Diseases and Clinical Microbiology ◽

10.5578/flora.68921 ◽

2020 ◽

Vol 25 (3) ◽

pp. 301-307

Author(s):

M. Duygu Aksoy ◽

H. Murat Tuğrul

Keyword(s):

Pseudomonas Aeruginosa ◽

Ethylenediaminetetraacetic Acid ◽

Carbapenem Resistance ◽

Beta Lactamase ◽

Bacterial Strains ◽

Beta Lactamases ◽

Carbapenem Resistant ◽

Synergy Test ◽

Phenotypic Tests ◽

Positive Controls

Introduction: Carbapenem resistant Pseudomonas aeruginosa strains cause serious problems in treatment. A large number of identified metallo-beta-lactamase (MBL) enzymes produced by P. aeruginosa are one of the most important mechanisms in resistance to carbapenems. MBL genes are located on the chromosome or plasmid, and they can easily spread between different bacterial strains. The activities of these enzymes are zinc-dependent, and they are inhibited by ethylenediaminetetraacetic acid (EDTA). Therefore, this advantage is used in MBL identification tests. In this study, it was aimed to determine MBL among P. aeruginosa strains. Materials and Methods: MBL existence was investigated in 35 P. aeruginosa strains accepted to be mildly susceptible/resistant to any of the carbapenem group of antibiotics through phenotypic and genotypic methods. Phenotypic tests were performed as double disk synergy test (DDST), combined disk diffusion tests (CDDT) by using 0.1 M and 0.5 M EDTA, MBL E-test, and modified Hodge test (MHT). blaIMP, blaVIM, blaGIM, blaSIM, blaSPM genes and blaNDM gene were investigated by multiplex polimerase chain reaction (PCR) and PCR, respectively. Escherichia coli ATCC 25922 and P. aeruginosa ATCC 27853 standard bacteria were used in tests. VIM-1, VIM-2, IMP-13, SPM-1, NDM-1 type MBL-producing P. aeruginosa strains were used as positive controls. Results: Among the carbapenems resistant P. aeruginosa isolates, positivity of MBL was found as 54.2% by MBL E-test, 42.8% by DDST, 94.2% and 37.1% by CDDT method using 0.5 M and 0.1 M EDTA, respectively. Modified Hodge test and genotypic method did not detect MBL. Conclusion: In order to correctly evaluate the results of the phenotypic method, the investigation of resistance genes by molecular methods is also required. The most common metallo-beta-lactamase enzymes responsible for resistance to carbapenem in Pseudomonas were not observed. It was thought that different mechanisms might be responsible for the identified carbapenem resistance.

Download Full-text

Detection of VIM and NDM-1 metallo-beta-lactamase genes in carbapenem-resistant Pseudomonas aeruginosa clinical strains in Bahrain

Journal of Laboratory Physicians ◽

10.4103/jlp.jlp_118_18 ◽

2019 ◽

Vol 11 (02) ◽

pp. 138-143 ◽

Cited By ~ 1

Author(s):

Ronni Mol Joji ◽

Nouf Al-Rashed ◽

Nermin Kamal Saeed ◽

Khalid Mubarak Bindayna

Keyword(s):

Pseudomonas Aeruginosa ◽

Multiple Drug Resistance ◽

Infectious Agent ◽

Carbapenem Resistance ◽

Conventional Polymerase Chain Reaction ◽

Control Measures ◽

Multiple Drug ◽

Beta Lactamase ◽

Infection Control Measures ◽

Carbapenem Resistant

Abstract INTRODUCTION: Carbapenem-resistant Pseudomonas aeruginosa has emerged as a life-threatening infectious agent worldwide. Carbapenemase genes are reported to be some of the most common mechanisms for carbapenem resistance in P. aeruginosa. No reports are available from the Kingdom of Bahrain about carbapenem resistance and the underlying cause. In this study, we determined to study the presence of the metallo-beta-lactamase (M β L) genes of VIM family and NDM-1 in carbapenem-resistant P. aeruginosa strains. METHODOLOGY: Fifty carbapenem-resistant P. aeruginosa isolates were obtained from three main hospitals of Bahrain. They were subjected to antimicrobial susceptibility testing by disc diffusion test. Subsequently, MβL was detected by imipenem-ethylene diamine tetraacetic acid (EDTA) combined disc test and conventional polymerase chain reaction. RESULTS: Among 50 P. aeruginosa strains, 40 (80%) were imipenem resistant. Among the 40 imipenem-resistant strains, 35 (87.5%) strains were positive for the imipenem-EDTA combined disc test, and 21 (52%) were carrying MβL genes. Nineteen (47.5%) strains were positive for the VIM gene; one (2.5%) strain was carrying the NDM-1 gene, while one strain was carrying both the VIM and NDM-1 genes. None of the imipenem sensitive strains carried the VIM or NDM-1 gene. CONCLUSION: This is the first study to report the presence of the VIM family gene and NDM-1 genes in imipenem-resistant P. aeruginosa isolates in the Kingdom of Bahrain. The study also confirms the multiple drug resistance by the MβL strains, attention should therefore from now on, be focused on prevention of further spread of such isolates by firm infection control measures, and to reduce its threat to public health.

Download Full-text

Carbapenemase Production of Clinical Isolates Acinetobacter baumannii and Pseudomonas aeruginosa from a Bulgarian University Hospital

Folia Medica ◽

10.1515/folmed-2017-0060 ◽

2017 ◽

Vol 59 (4) ◽

pp. 413-422 ◽

Cited By ~ 1

Author(s):

Atanaska P. Petrova ◽

Irina D. Stanimirova ◽

Ivan N. Ivanov ◽

Michael M. Petrov ◽

Tsonka M. Miteva-Katrandzhieva ◽

...

Keyword(s):

Pseudomonas Aeruginosa ◽

Acinetobacter Baumannii ◽

Insertion Sequence ◽

Susceptibility Testing ◽

Transmembrane Protein ◽

Carbapenem Resistance ◽

University Hospital ◽

Gram Negative ◽

Main Factors ◽

Hospital Wards

AbstractBackground: Production of Bla OXA-23, OXA-24, OXA-58 and hyperexpression of OXA-51 due to ISAba1 insertion sequence are the leading causes of carbapenem resistance in Acinetobacter baumannii. The loss of OprD transmembrane protein and the overexpression of some effl ux pumps are considered to be the main factors for carbapenem resistance in Pseudomonas aeruginosa whereas metallo-enzymes’ production has a secondary role. Aim: Тo examine the carbapenem resistance due to carbapenemase production among clinically signifi cant Gram-negative non-fermenters from St George University hospital, Plovdiv: A. baumannii and P. aeruginosa. Materials and methods: Forty three A. baumannii and 43 P. aeruginosa isolates, resistant or with intermediate resistance to imipenem and/or meropenem were included in the study. They were collected from patients admitted in 14 various hospital wards between 2010 and 2014. Both phenotypic and genetic methods were used for identifi cation and antimicrobial susceptibility testing. Results: All A. baumannii demonstrated carbapenemase production determined by a modifi ed Hodge test whereas P. aeruginosa isolates did not show this phenomenon. OXA-23 genes were determined in 97.7% (42 out of 43) of A. baumannii isolates indistinguishable from the sequence of the classical ARI-1 gene. OXA-24, OXA-58 and overexpression of OXA-51 were not registered in any of the isolates. All P. aeruginosa were negative for blaVIM and blaIMP genes. Conclusion: The leading cause of carbapenem resistance in A. baumannii isolates from our hospital is the carbapenemase production due to the expression of OXA- 23 gene, whereas in P. aeruginosa - the loss of transmembrane OprD protein and the effl ux pumps’ hyperexpression are suspected to be the main mechanisms.

Download Full-text

Reduction in Fluoroquinolone Use following Introduction of Ertapenem into a Hospital Formulary Is Associated with Improvement in Susceptibility of Pseudomonas aeruginosa to Group 2 Carbapenems: a 10-Year Study

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00742-11 ◽

2011 ◽

Vol 55 (12) ◽

pp. 5597-5601 ◽

Cited By ~ 20

Author(s):

Paul P. Cook ◽

Michael Gooch ◽

Shemra Rizzo

Keyword(s):

Pseudomonas Aeruginosa ◽

Pearson Correlation ◽

Tertiary Care ◽

Carbapenem Resistance ◽

Antibiotic Use ◽

Care Hospital ◽

Hospital Formulary ◽

Content Type ◽

Carbapenem Resistant ◽

Group 2

ABSTRACTWe examined the effect of the addition of ertapenem to our hospital formulary on the resistance of nosocomialPseudomonas aeruginosato group 2 carbapenems (imipenem, meropenem, and doripenem). This was a retrospective, observational study conducted between 1 January 2000 and 31 January 2009 at a large, tertiary-care hospital. Autoregressive integrated moving average (ARIMA) regression models were used to evaluate the effect of ertapenem use on the susceptibility ofPseudomonas aeruginosato group 2 carbapenems as well as on the use of the group 2 carbapenems, ciprofloxacin, and other antipseudomonal drugs (i.e., tobramycin, cefepime, and piperacillin-tazobactam). Resistance was expressed as a percentage of total isolates as well as the number of carbapenem-resistant bacterial isolates per 10,000 patient days. Pearson correlation was used to assess the relationship between antibiotic use and carbapenem resistance. Following the addition of ertapenem to the formulary, there was a statistically significant decrease in the percentage ofPseudomonas aeruginosaisolates resistant to the group 2 carbapenems (P= 0.003). Group 2 carbapenem use and the number of carbapenem-resistantPseudomonas aeruginosaisolates per 10,000 patient days did not change significantly over the time period. There was a large decrease in the use of ciprofloxacin (P= 0.0033), and there was a correlation of ciprofloxacin use with the percentage of isolates resistant to the group 2 carbapenems (ρ = 0.47,P= 0.002). We suspect that the improvement in susceptibility ofPseudomonas aeruginosato group 2 carbapenems was related to a decrease in ciprofloxacin use.

Download Full-text