Ertapenem Disk Research Articles

Detection of carbapenemase producing enterobacterales using the Modified Hodge Test from clinical isolates in Colombo South Teaching Hospital and Sri Jayewardenepura General Hospital, Sri Lanka in 2017

Introduction: Enterobacterales is a large family of Gram-negative bacilli including many pathogens. Carbapenemase producing Enterobacterales (CPEs) have emerged as a global threat. This study was conducted to detect carbapenemase production by Enterobacterales isolates from clinical specimens and to correlate the occurrence of CPE with age, gender, and duration of hospital stay of the patients included in the study.Methods: A descriptive cross-sectional study was carried out using 120 consecutive, non-repetitive clinical isolates identified as Enterobacterales by the microbiology laboratories of Colombo South Teaching Hospital and Sri Jayewardenepura General Hospital. The demographic data of the patients was gathered and used to analyse the correlation with CPE occurrence. All isolates were identified up to species level using API 20E kits. Screening for detection of carbapenemase was carried out using meropenem, imipenem, and ertapenem disks. The Modified Hodge Test (MHT), which is one of the suggested procedures to determine carbapenemase production, was performed to identify carbapenemase producing isolates.Results: Of the120 isolates, 14 (11.7%) were resistant to at least one of the carbapenems tested. MHT detected carbapenemase production in ten (8.3%) isolates. The majority of these isolates were Klebsiella sp. (6; 60.0%). Of carbapenemase producing isolates, six were from urine specimens (60%). Eight (80.0%) of the CPE harbouring patients were males and eight (80.0%) were aged above 50 years. The mean duration of hospital stay of the patients was 7.2 days (±SD 5.65days).Conclusion: The proportion of CPE was 8.3% according to this study and emphasises the importance of conducting more studies on the prevalence of CPE in Sri Lanka.

An observational study on carbapenem-resistant Enterobacterales (CRE) colonisation and subsequent risk of infection in an adult intensive care unit (ICU) at a tertiary care hospital in India

Carbapenem-resistant Enterobacterales (CRE) are a global health problem with a growing prevalence. India has a high prevalence of CRE. CRE infections are difficult to treat, and are associated with significant morbidity and mortality. Colonisation is generally a prerequisite for infection and the prevention of CRE colonisation is key to the prevention of CRE infection. To determine the prevalence of CRE colonisation and subsequent infections in an adult intensive care unit (ICU) in India. We conducted a prospective observational study in which perirectal swabs were obtained along with relevant clinical details of consenting adult patients upon ICU admission between January 2019 and August 2020. Rectal screening was performed using MacConkey agar plates with ertapenem disks and further identification was performed using conventional microbiological techniques. Ertapenem minimum inhibitory concentration (MIC) was determined using an epsillometer (E) test. The modified carbapenem inactivation (mCIM) test and EDTA carbapenem inactivation test (eCIM) were performed to confirm carbapenem resistance using the Clinical Laboratory Standards Institute (CLSI) 2020 guidelines. 192 ICU patients were screened for CRE. 37 patients were found to be colonised with CRE. Klebsiella pneumoniae (N=25; 67.6%) was the most frequent CRE isolate, followed by Escherichia coli (N=11; 29.7%) and one Enterobacter species (N=1; 2.7%). 89.2% (33/37) patients developed CRE infection. Pneumonia was the most common CRE infection identified in 12/33 (36.4%) patients.during the hospital stay. The median duration of hospital stay was longer (17 days) for CRE colonised compared to CRE non-colonised patients (9 days) (P<0.001). Death occurred in 27 % (N=10/37) of CRE-colonised patients during the hospital admission. CRE colonisation is associated with high risk of subsequent CRE infection and longer ICU and hospital admission.

Screening of Carbapenem Resistance Klebsiella pneumoniae and its MIC against Imipenem

Klebsiella pneumoniae is a common opportunistic pathogen causing a wide range of infections; pneumonia, urinary tract infection, bacteremia, and liver abscesses. It infects primarily immunocompromised and immunocompetent individuals. It presents itself as an antibiotic-resistant bacterium, especially for third-generation cephalosporins and carbapenems, creating serious global challenges. Therefore, this cross-sectional study was conducted in B &amp; B Hospital, Lalitpur to screen the distribution of carbapenem resistance K. pneumoniae through ertapenem and to assess the minimum inhibitory concentration of imipenem for screened carbapenem resistance K. pneumoniae. From 3447 different clinical samples collected according to standard guidelines, K. pneumoniae was identified using standard microbiological techniques; staining and a panel of biochemical tests. The antibiotic susceptibility test of the isolates was performed by the Kirby-Bauer disc diffusion method as per CLSI 2018 guidelines. The screening of carbapenem resistance was assessed by using ertapenem disc and the MIC of imipenem for carbapenem resistance and intermediate was performed using an Epsilometer. A total of 85 K. pneumoniae were identified and their antibiotic susceptibility test revealed that ceftriaxone was the least effective antibiotic. The number of MDR, carbapenem-resistant and intermediate isolates was 51, 46, and 3, respectively. The MIC of imipenem through an Epsilometer from ertapenem resistant and intermediate revealed that 31, 5, and 13 isolates were resistant, intermediate, and sensitive respectively. These findings showed the inconsistency in the detection of carbapenem-resistant isolates in routine microbiology laboratories and further support the other tests for the detection of carbapenem resistance as suggested by CLSI.

Phenotypic Detection and Molecular Characterization of Carbapenem-Resistant Enterobacteriaceae at a Tertiary Care Center

Background: Carbapenem-resistant Enterobacteriaceae (CRE) is of utmost clinical importance because they challenge the armamentarium of the treating clinicians, hampering current treatment strategies. Aim: The aim of the study is to detect carbapenemase-producing Enterobacteriaceae by phenotypic and molecular methods. Materials and Methods: Nonrepetitive isolates of Enterobacteriaceae were identified by conventional phenotypic methods from various clinical samples. All these isolates were screened for carbapenem resistance by meropenem (10μg) or ertapenem (10μg) disc. All the isolates which were found to be carbapenem-resistant by screening test were subjected to phenotypic confirmatory test in the form of modified Hodge test (MHT). These isolates were then subjected to polymerase chain reaction for the detection of various carbapenemase-producing genes, namely New Delhi metallo-β-lactamase 1 (NDM), verona integron-encoded metallo-β-lactamase (VIM), imipenem-resistant Pseudomonas (IMP), KPC, and OXA-48. Results: Out of 1254 isolates of Enterobacteriaceae, 230 isolates (18.3%) were found to be positive for carbapenemase production by screening test. A total of 150 out of 230 isolates (65.2%) tested positive for carbapenemase production by MHT. Out of these 150 phenotypically confirmed carbapenemase-producing isolates, blaNDM gene was found in 85, blaVIM in 32, and blaIMP in 22 isolates. blaOXA-48 and blaKPC genes were not found in any isolate. Moreover, there were 19 isolates, in which no gene was detected. Conclusion: The prevalence of phenotypically confirmed carbapenemase resistance among Enterobacteriaceae is 11.96% (150/1254). Genes responsible for carbapenemase production are widely prevalent in Enterobacteriaceae Routine detection will help in the management of these broadly-resistant pathogens and implementation of appropriate infection control measures, thus limiting their spread.

A Variant Carbapenem Inactivation Method (CIM) for Acinetobacter baumannii Group with Shortened Time-to-Result: rCIM-A.

Carbapenem-resistant Acinetobacter baumannii group organisms (CRAB) are challenging because the choice between targeted, new antibiotic drug options and hygiene measures should be guided by a timely identification of resistance mechanisms. In CRAB, acquired class-D carbapenemases (CHDLs) are active against meropenem and imipenem. If PCR methods are not the first choice, phenotypic methods have to be implemented. While promising, the carbapenemase inactivation method (CIM) using meropenem-hydrolysis is, however, hampered by poor performance or overly long time-to-result. We developed a rapid CIM (rCIM-A) with good performance using ertapenem, imipenem, and meropenem disks, 2-h permeabilization and incubation with the test strain in trypticase soy broth, and a read-out of residual carbapenem activity after 6 h, and optionally after 16–18 h. Using clinical isolates and type-strains of Acinetobacter (n = 67) not harboring carbapenemases (n = 28) or harboring acquired carbapenemases (n = 39), the sensitivity of detection was 97.4% with the imipenem disk after 6 h at a specificity of 92.9%. If the inhibition zone around the ertapenem disk at 6 h was 6 or ≤26 mm at 16–18 h, or ≤25.5 mm for meropenem, the specificity was 100%. Because of the high negative predictive value, the rCIM-A seems particularly appropriate in areas of lower CRAB-frequency.

An Observational Study on CRE Colonization and Subsequent Risk of Infection in Adult ICU Patients

Background: Carbapenem-resistant Enterobactericeae (CRE) has emerged as a global health threat with increasing incidence. It is a particular problem in India because control over antibiotics prescription is really poor; these agents can be easily bought over the counter and the antibiotic prescription threshold is low among Indian doctors. Also, even when administered, antibiotics are given in inappropriate dosages and durations. CRE infections are a healthcare challenge due to their difficulty to treat and high morbidity and mortality. Colonization requires infection prevention measures, and it should be prioritized. Methods: We sought to determine the prevalence rate of CRE colonization in the gastrointestinal tract in newly admitted ICU patients along with follow-up of any subsequent infection following colonization. A prospective observational study was carried out among ICU patients from January 2019 to August 2020 by collecting perirectal swabs from patients who gave consent. Clinical variables were identified, and the relationship between CRE colonization and subsequent systemic CRE infection was assessed. Processing was carried out by culturing on MacConkey agar plate with ertapenem disk and further identified using conventional microbiological techniques. The ertapenem MIC was determined using an Epsillometer (E) test. The modified carbapenem inactivation (mCIM) test and the EDTA carbapenem inactivation method (eCIM) were used to confirm carbapenem resistance using Clinical Laboratory Standards Institute 2020 guidelines (Figure 1). Results: Among 192 ICU patients, 37 (19.27%) were colonized with CRE (Table 1). Also, 13 (35.13%) CRE isolates showed metallo-β-lactamase resistance. Furthermore, 18 CRE isolates (48.64%) showed serine carbapenemase activity; 6 CRE isolates showed no carbapenemase activity. Klebsiella pneumoniae (n = 25 of 37, 67.56%) was the most common CRE isolated followed by Escherichia coli (n = 11 of 37, 29.72%) and 1 isolate of Enterobacter spp (n = 1 of 37, 0.02%). Of 37 patients, 33 (89.18%) developed CRE infection during their hospital stay. Pneumonia was the most common infection developed (36.36%), followed by surgical site infection (21.21%) and urinary tract infection (12.12%). Only 1 patient developed a bloodstream infection. However, 9 patients (27.27%) developed multiple-site infections. Of 37 CRE-colonized patients, 10 (27.02%) died during their hospital stay. Conclusions: Our study highlights the increased risk of CRE infection and mortality in patients with CRE colonization in ICU patients. Hence, CRE perirectal screening for detection of asymptomatic carriers should be conducted, and strict infection control measures, such as isolation and cohorting with barrier nursing of such patients, should be done to prevent further spread of CREs in hospital settings.Funding: NoDisclosures: None

Carbapenem-resistant Enterobacteriaceae infections among patients admitted to intensive care units in Kano, Nigeria

Background: Globally, intensive care units (ICUs) are encountering emergence and spread of antibiotic-resistant pathogens, and for some pathogens, there are few therapeutic options available. Objectives: The study assessed prevalence, susceptibility pattern, and risk factors of carbapenem-resistant Enterobacteriaceae (CRE) infections among ICU patients in Kano, Nigeria. Materials and Methods: A descriptive cross-sectional study was used to study 190 patients admitted to the ICUs of two tertiary hospitals in Kano. Antibiotic susceptibility of isolated organisms was determined by disc diffusion technique. Suspected carbapenemase producers were further subjected to the modified Hodge test (MHT) method for confirmation. Results: A total of 76 out of the 190 samples yielded clinical isolates of Enterobacteriaceae as follows: 34 (44.7%) Escherichia coli, 19 (25%) Klebsiella pneumoniae, 3 (3.9%) Proteus mirabilis, 4 (5.3%) Enterobacter aerogenes, 3 (3.9%) Proteus vulgaris, 2 (2.6%) Citrobacter freundii, 2 (2.6%) Klebsiella ozaenae, 2 (2.6%) Klebsiella oxytoca, 2 (2.6%) Salmonella subsp. 3b, 2 (2.6%) Enterobacter agglomerans, 2 (2.6%) Enterobacter cloacae, and 1 (1.3%) Serratia odorifera. Screening the Enterobacteriaceae-positive samples for carbapenem resistance using ertapenem disc (10 μg) showed 8 samples (10.5%) as resistant while MHT gave a carbapenem resistance prevalence of 7.9% (6 out of 76). Based on multiplex polymerase chain reaction; the distributions of genotypes of the carbapenemase producers were as follows: Verona Integron Metallo-beta-lactamase (VIM) genes only (4 [50%]) New Delhi Metallo-beta-lactamase (NDM) genes only (2 [25%]), and 1 (12.5%) had Klebsiella pneumoniae carbapenemase (KPC) and VIM gene coexisting. Surgical procedure (P = 0.009) and history of recent admission (P = 0.001) were found to be risk factors for CRE. Conclusion: The study provided evidence of the presence of CRE infections among patients admitted to ICUs in the study centers. This underscores the need for effective infection prevention and control measures to avoid the spread of CRE in hospital setting.

Clinical Relevance of Antibiotic Susceptibility Profiles for Screening Gram-negative Microorganisms Resistant to Beta-Lactam Antibiotics.

The increasing resistance to antibiotics is compromising the empirical treatment of infections caused by resistant bacteria. Rapid, efficient, and clinically applicable phenotypic methods are needed for their detection. This study examines the phenotypic behavior of β-lactam-resistant Gram-negative bacteria grown on ChromID ESBL medium with ertapenem, cefoxitin, and cefepime disks, reports on the coloration of colonies, and establishes a halo diameter breakpoint for the detection of carbapenemase-producing bacteria. We studied 186 β-lactam-resistant Gram-negative microorganisms (77 with extended spectrum beta lactamase (ESBL), 97 with carbapenemases, and 12 with AmpC β-lactamases (AmpC)). Susceptibility profiles of Gram-negative bacteria that produced ESBL, AmpC, and carbapenemases were similar to the expected profiles, with some differences in the response to cefepime of ESBL-producing microorganisms. Coloration values did not differ from those described by the manufacturer of ChromID ESBL medium. In the screening of carbapenemase production, inhibition halo diameter breakpoints for antibiotic resistance were 18 mm for Enterobacterales and ertapenem, 18 mm for Pseudomonas and cefepime, and 16 mm for Acinetobacter baumannii and cefepime. This innovative phenotypic approach is highly relevant to clinical laboratories, combining susceptibility profiles with detection by coloration of high-priority resistant microorganisms such as carbapenemase-producing A. baumannii, carbapenemase-producing Pseudomonas spp., and ESBL and/or carbapenemase-producing Enterobacterales.

Antibiogram, Prevalence of OXA Carbapenemase Encoding Genes, and RAPD-Genotyping of Multidrug-Resistant Acinetobacter baumannii Incriminated in Hidden Community-Acquired Infections.

Acinetobacter spp. has gained fame from their ability to resist difficult conditions and their constant development of antimicrobial resistance. This study aimed to investigate the prevalence, susceptibility testing, OXA carbapenemase-encoding genes, and RAPD-genotyping of multidrug resistant Acinetobacter baumannii incriminated in hidden community-acquired infections in Egypt. The antimicrobial susceptibility testing was assessed phenotypically using Kirby–Bauer disk diffusion method. Also, Modified-Hodge test (MHT) was carried out to detect the carbapenemases production. Multiplex-PCR was used to detect the carbapenemase-encoding genes. Furthermore, the genetic relationship among the isolated strains was investigated using RAPD fingerprinting. The bacteriological examination revealed that, out of 200 Gram-negative non-fermentative isolates, 44 (22%) were identified phenotypically and biochemically as Acinetobacter spp. and 23 (11.5%) were molecularly confirmed as A. baumannii. The retrieved A. baumannii strains were isolated from urine (69%), sputum (22%), and cerebrospinal fluid (csf) (9%). The isolated A. baumannii strains exhibited multidrug resistance and the production rates of carbapenemases were 56.5, 60.9, and 78.3% with meropenem, imipenem, and ertapenem disks, respectively. The blaOXA-24-like genes were the most predominant among the tested strains (65.2%), followed by blaOXA-23 (30.4%) and blaOXA-58 (17.4%), in addition, the examined strains are harbored IMP, VIM, and NDM genes with prevalence of 60.9, 43.5, and 13%, respectively, while KPC and GES genes were not detected. RAPD-PCR revealed that the examined strains are clustered into 11 different genotypes at ≥90% similarity. Briefly, to the best of our knowledge, this study is the first report concerning community-associated A. baumannii infections in Egypt. The high prevalence of hidden multidrug-resistant (MDR) and extensively drug-resistant (XDR) A. baumannii strains associated with non-hospitalized patients raises an alarm for healthcare authorities to set strict standards to control the spread of such pathogens with high rates of morbidity and mortality.

Use of Ertapenem as a Marker for Detection of Carbapenem Resistance for Enterobacteriaceae

Introduction: Detection of carbapenem resistance in the clinical microbiology laboratory is challenging. Production of carbapenemase enzymes remains the most important mechanism among Carbapenem Resistant Enterobacteriaceae (CRE). Ertapenem has been found as a sensitive marker for detecting CRE, especially the non-carbapenemase producing CRE. However, limited literature is available discussing its specificity and sensitivity in comparison to gold standard tests. Aim: To compare the ability of the ertapenem disc diffusion test with other confirmatory tests i.e., Epsilometer test (E test), Carbapenemase Nordmann-Poirel (CNP) test, and Polymerase Chain Reaction (PCR) for CRE identification. Materials and Methods: Seventy six phenotypically confirmed Enterobacteriaceae isolates were tested for carbapenem resistance. Ertapenem susceptibility was compared with imipenem, meropenem, and doripenem disc individually and in combination to determine its sensitivity. Further, it was compared with the E test, CNP test, and PCR to find the concordance of the result. Data were analysed by statistical software using Chi-square test with p-value &lt;0.05 as significant. Results: Ertapenem disc independently was able to detect maximum resistant isolates (64/76) in comparison to other individual carbapenem discs or their combinations. Among the four carbapenem discs, the result of the ertapenem disc showed maximum concordance with its corresponding E test. The sensitivity, specificity, Positive Predictive Value (PPV), and Negative Predictive Value (NPV) of the Ertapenem disc compared to the gold standard tests (CNP and PCR) were 89.7%, 62.5%, 95.3%, and 41.7%, respectively. Conclusion: Disc diffusion test using ertapenem disc was observed as a sensitive marker for detecting CRE. The result of the ertapenem disc diffusion test was observed less discordant with E test, CNP test, and PCR in comparison to other carbapenem discs.

532. Can Saccharomyces boulardii Therapy Be Effective in Decolonizing Rectal Carbapenem-Resistant Enterobacteriaceae (CRE) Colonization?

BackgroundCRE are globally important pathogens associated with significant morbidity and mortality. The problem of carrying CRE may continue to create a problem in discharged cases in the community. Saccharomyces boulardii sachet therapy (SBST) is reported to cause decolonization in several MDR bacteria carriers. Herein, it is aimed to present the decolonizing rates of rectal CRE colonized cases after SBST treatment.MethodsThe study period was August 2018–March 2019. Inclusion criteria were: (i) age >18, (ii) receiving Saccharomyces boulardii 250 mg sachets q12h for 7 days, (iii) being proven CRE carrier on rectal swab culture (RSC) up to 5 days period before SBST. The first repeated RSC was performed 3–5 days after the end of SBST. Data were retrieved from the hospital electronic database. Cases with three consecutive weekly performed negative RSC were considered to be decolonized. RSC were processed according to CDC protocol; briefly, the swab was inoculated into 10 mL of trypticase soy broth (bioMérieux Inc., Marcy-l’Étoile, France) with the addition of one 10-μg ertapenem disk (Oxoid, Altrincham, UK) and incubated at 35°C for 18–20 h. The next day, after vortexing, 100 μL of the inoculum was subcultured (8) onto chromID CARBA agar plates (bioMérieux) and incubated at 35°C for 18–20 h. Suspected CRE colonies on chromID CARBA (blue/green to blue/gray in color) were identified by the VITEK MS system (bioMérieux). Susceptibility testing of the isolates was performed with the VITEK 2 system (bioMérieux). Isolates were tested for their resistance phenotypes to imipenem, ertapenem, and meropenem by E-test (bioMérieux). The results were interpreted according to the EUCAST criteria.ResultsFifteen cases [2 women, mean age 60.6 ± 18.3 (min. 18–max. 83)] fulfilled the inclusion criteria. All had a history of carbapenem usage. Five cases (33%) had three consequent negative RSC after SBST and were considered to be decolonized. Twelve cases were receiving concomitant antibiotic during SBST (10 carbapenem based regimens). Three cases who received no concomitant antibiotic were decolonized.ConclusionSBST may be a promising tool for decolonizing CRE carriers. These data need to be validated in larger cohorts preferably via randomized-controlled trials.Disclosures All authors: No reported disclosures.

Detection of carbapenamase production by rapid carba NP test among Enterobacteriaceae isolates in tertiary care hospital

Detection of carbapenamase production by rapid carba NP test among Enterobacteriaceae isolates in tertiary care hospital - IJMR- Print ISSN No: - 2394-546X Online ISSN No:- 2394-5478 Article DOI No:- 10.18231/j.ijmr.2019.059, Indian Journal of Microbiology Research-Indian J Microbiol Res

Comparison of three phenotypic methods for the screening of carbapenem resistance among clinical isolates of Enterobacteriaceae

Background: The global use, misuse, and abuse of broad-spectrum antibiotics coupled with failure of development of newer effective antibiotics have led to the rapid spread of carbapenemase producing Gram-negative Enterobacteriaceae. The lack of capacity for effective diagnosis results in increased morbidity, prolonged hospitalization, suboptimal treatment leading to treatment failure, and increased healthcare cost. Aims/objectives: We set out to determine the best method(s) for the phenotypic screening of carbapenem resistance among the species of Enterobacteriaceae at University of Maiduguri Teaching Hospital (UMTH). Materials and Methods: We screened all patients admitted into various wards/units of UMTH over a 6-month period to isolate Enterobacteriaceae. We used an interviewer-administered questionnaire to obtain some basic information from the patients. We confirmed the species of Enterobacteriaceae using Microbact Gram-negative 24E test kit. All confirmed isolates were screened for carbapenem resistance with Meropenem and Ertapenem antibiotic discs (10 μg, Oxoid, UK) according to the Clinical and Laboratory Standards Institute (CLSI) guideline. Minimum inhibitory concentration (MIC) using Etest of Imipenem (Biomeriux) was also determined based on CLSI recommendations. Modified Hodge test method was considered as a gold standard for confirmatory test. The three methods were compared with the gold standard. Results: We isolated 225 Enterobacteriaceae from 225 patients. Klebsiella pneumoniae had the highest proportion of 73 (32.4%). The sensitivity of the different methods in increasing order was 95.7% for Meropenem disk (10 μg), 100% for Ertapenem disk (10 μg), and 100% for Imipenem MIC. Conclusion: In view of cost and availability, the Ertapenem disc (10 μg) method can be used for the screening of carbapenem-resistant Enterobacteriaceae. For the routine screening of carbapenem resistance Enterobacteriaceae in our clinical laboratories, the Ertapenem disc (10 μg) method is recommended.

Evaluation of Modified Hodge Test as a Non-molecular Assay for Accurate Detection of KPC-producing Klebsiella pneumoniae

Klebsiella pneumoniae carbapenemase (KPC) have become a major therapeutic challenge because of its increasingly fast dissemination throughout the world. Accurate detection of KPC is essential for optimal treatment. The Clinical and Laboratory Standards Institutes (CLSI) for fast detection of KPC producers currently recommend Modified Hodge Test (MHT) and Carba NP test. MHT can directly detect carbapenemase production in Enterobacteriaceae isolates. The current study was conducted to evaluate the capacity of MHT with two carbapenem disks for accurate detection of KPC. MHT was performed according to guidelines of CLSI to identify isolates with carbapenem resistance. In doing so, two substrates of MHT were assigned into two groups for examination: meropenem and ertapenem groups. A total of 96 non-repetitive clinical isolates of Klebsiella pneumoniae were tested. The presence of the blaKPC gene in each MHT-positive isolate was examined by PCR. A total of 54 isolates exhibited reduced susceptibility or resistance to carbapenems. Sensitivity of MHT with two carbapenem disks was similar. Specificity of the MHT with meropenem disk was 64% and with ertapenem disk was 53%. Detection of KPC by MHT with meropenem disk was found to be more effective than with ertapenem disk. Based on our results, the presence of KPC does not in itself influence the categorization of resistance. Therefore, the use of MHT with ertapenem disk for the rapid detection of KPC among K. pneumoniae for infection control should not be recommended.

Carba NP as a simpler, rapid, cost-effective, and a more sensitive alternative to other phenotypic tests for detection of carbapenem resistance in routine diagnostic laboratories.

PURPOSE:Resistance to carbapenems due to carbapenemases has been increasingly noticed in Enterobacteriaceae. Clinical and Laboratory Standards Institute (CLSI) has recommended the latest Carba NP (CNP) test as a confirmatory test for carbapenemase production in Enterobacteriaceae. Low sensitivity of disk diffusion (DD) and modified Hodge test (MHT) may result in missing out of resistant strains which can adversely affect clinical management. The present study compares three phenotypic tests - CNP test, DD, and MHT for detection of carbapenemase production.MATERIALS AND METHODS:Four hundred consecutive, nonduplicate Enterobacteriaceae isolates were tested for carbapenem resistance using ertapenem disc (10 μg) by Kirby–Bauer DD method, MHT, and CNP. These tests were performed and interpreted as per the CLSI standards. CNP was considered to be the reference test for comparison. Sensitivity, specificity, and accuracy rates for ertapenem DD and MHT were calculated.RESULTS:One hundred and six out of 400 strains were positive by CNP test. Of the 294 CNP-negative strains, 28 were resistant by DD and 18 were resistant by MHT. Of the 106 CNP-positive strains, 82 were resistant and 16 were intermediate by DD while 76 were positive by MHT ertapenem DD had a sensitivity and specificity of 66.04% and 90.48%, respectively. Sensitivity and specificity of MHT were 54.72% and 93.88%, respectively. There was considerable discordance between all the three tests.CONCLUSION:As a rapid, simple, and cost-effective test with a greater capability greater to detect carbapenemase producers, CNP can be implemented in routine diagnostic laboratories, thereby benefiting patient care and antimicrobial stewardship.

Retrospective and prospective evaluation of the Carbapenem inactivation method for the detection of carbapenemase-producing Enterobacteriaceae.

BackgroundThere is an urgent need for accurate and rapid diagnostic tests to identify carbapenemase producing enterobacteria (CPE). Here, we have evaluated the Carbapenem Inactivation Method (CIM) test to detect CPEs from cultured colonies.MethodsA total of 256 enterobacterial isolates were used to evaluate the performance of the CIM in comparison to Carba NP test and molecular detection used a reference method. Ninety three well-characterized isolates (including 29 non-CPE and 63 CPEs of worldwide origin) with decreased susceptibility to at least one carbapenem were used to (i) evaluate the efficacy of CIM test and (ii) to compare it to the Carba NP test. We also tested different carbapenems to determine the best substrate for this test. Finally, the CIM test was then evaluated prospectively against 164 isolates referred to the French National Reference Center (NRC) for Antimicrobial Resistance from may 2016 to july 2016.ResultsBased on the results of this retrospective study, sensitivity and specificity of the CIM and the Carba NP test were 92.1% and 100%, respectively. We demonstrated that the meropenem was the best substrate to perform the CIM test since sensitivity and specificity were 81.1% and 100% using ertapenem disk, and 100% and 65,6% using imipenem disk, and respectively. Taking in account the results of retrospective and prospective studies, CIM and Carba NP tests have similar sensitivity, specificity, positive predictive value and negative predictive values being 96.3%, 98.9%, 99.0% and 98.4% for the CIM test versus 96.9%, 100%, 100% and 100% for the Carba NP test.ConclusionsOur results confirm that the CIM test may be a useful tool for the reliable confirmation of carbapenemase-activity in enterobacterial isolates, especially in clinical microbiological laboratories with limited resources, no trained personnel, and no specialized equipment.

Investigation of carbapenem resistance and the first identification of Klebsiella pneumoniae carbapenemase (KPC) enzyme among Escherichia coli isolates in Turkey: A prospective study.

The aim of this study was to determine the presence of carbapenem resistance and carbapenemase production in Escherichia coli isolates from clinical samples in Turkey. The prospective study included a total of 4.052 Escherichia coli isolates collected from patients admitted to a hospital from March 2011 to May 2012. We used ertapenem disc for screening carbapenemase production, and the confirmation was performed by using Etest. The resistance mechanisms and genetic relatedness of the carbapenem resistant strains were investigated by using PCR (polymerase chain reaction) and pulsed-field gel electrophoresis (PFGE), respectively. Among the 4.052 E.coli isolates, 24 (0.59%) were found to be carbapenem resistant. Of these, only 5 isolates were positive for OXA-48 and 2 isolates were positive for Klebsiella pneumoniae carbapenemase (KPC)-2. The KPC-2 producing E.coli strains (n=2) were both isolated from the same patient. The blaKPC genes were confirmed using DNA sequence analysis. The genetic relationship between the 24 E.coli strains studied by PFGE revealed that the strains were genetically unrelated. This article confirms, to our knowledge for the first time, the detection of KPC-2-producing E.coli in Turkey, with OXA-48 being the most frequent carbapenemase in the study.

Carbapenemase-producing Enterobacteriaceae in hospital wastewater: a reservoir that may be unrelated to clinical isolates

Carbapenemase-producing Enterobacteriaceae (CPE) are an emerging infection control problem in hospitals worldwide. Identifying carriers may help reduce potential spread and infections. To assess whether testing hospital wastewater for CPE can supplement patient-based screening for infection prevention purposes in a hospital without a recognized endemic CPE problem. Wastewater collected from hospital pipework on 16 occasions during February to March 2014 was screened for CPE using chromID(®) CARBA agar and chromID(®) CPS agar with a 10μg ertapenem disc and combination disc testing. Minimum inhibitory concentrations were determined using British Society for Antimicrobial Chemotherapy methodology and carbapenemase genes detected by polymerase chain reaction or whole-genome sequencing. Selected isolates were typed by pulsed-field gel electrophoresis. Suspected CPE were recovered from all 16 wastewater samples. Of 17 isolates sent to the Antimicrobial Resistance and Healthcare Associated Infections Reference Unit, six (four Citrobacter freundii and two Enterobacter cloacae complex) were New Delhi metallo-β-lactamase (NDM) producers and the remaining 11 (six Klebsiella oxytoca and five Enterobacter cloacae complex) were Guiana-Extended-Spectrum-5 (GES-5) producers, the first to be described among Enterobacteriaceae in the UK. The four NDM-producing C.freundii, two NDM-producing E.cloacae complex, and four out of five GES-5-producing E.cloacae complex were each indistinguishable isolates of the same three strains, whereas the six GES-5-producing K.oxytoca overall shared 79% similarity. CPE are readily isolated from hospital wastewater using simple culture methods. There are either undetected carriers of CPE excreting into the wastewater, or these CPE represent colonization of the pipework from other sources. Surveillance of hospital wastewater for CPE does not appear helpful for infection control purposes within acute hospitals.

Evaluation of phenotypic tests to detect carbapenem-resistant Enterobacteriaceae in colonized patients hospitalized in intensive care units

In this study, we aimed to evaluate the performance of different phenotypic tests to detect carbapenem-resistant Enterobacteriaceae.Three different phenotypic methods were evaluated: (1) combined-disk test of meropenem plus phenylboronic acid or EDTA reading after 24h and 48h; (2) selective/chromogenic read after 24h and after 48h; and (3) overnight selective enrichment broth containing 10μg ertapenem disk followed by culture on MacConkey agar. A positive result in at least one of the methods was submitted to PCR for blaNDM-1, blaOXA-48, blaKPC, blaSPM-1, blaIMP, and blaGES detection.Carbapenem-resistant Enterobacteriaceae was detected in 31 (30.4%) of 102 rectal swabs evaluated. All isolates showed to be KPC-2-producing organisms. Results showed excellent agreement among the evaluated tests (positive and negative) (kappa=0.88).It is important to state that combined-disk test with phenylboronic acid is not suitable for bacterial identification/isolation. Conversely, selective/chromogenic agar after 48h of incubation showed to be a useful tool, with the advantage of presumptive bacterial identification.

Prevalence of fecal carriage of extended-spectrum- and metallo-β-lactamase-producing gram-negative bacteria among neonates born in a hospital setting in central Saudi Arabia.

BACKGROUND AND OBJECTIVECommensal neonatal fecal flora constitute a reservoir of antibiotic resistance. The aim of this study was to characterize the prevalence of fecal carriage of extended spectrum beta-lactamases (ESBLs) and carbapenemase producing gram-negative bacteria among 150 neonates who were born in two hospitals in central Saudi Arabia.PATIENTS AND METHODSFrom June 2012 to Janauary 2013, 150 healthy neonates ≤7 days of age were screened for intestinal enteric bacteria colonization and the influence of age, mode of delivery, body weight and breast feeding of neonates on colonzation rates. The isolates were identified manually and by VITEK 2 and antibiotic susceptibility was tested. Phenotypic tests were performed to seek ESBL and metallo-β-lactamase (MBL) producers in recovered isolates.RESULTSAmong 150 fecal specimens, 188 gram-negative rods were recovered. E coli (n=130; 69.1%) was the commonest organism followed by Klebsiella pneumoniae (n=23; 12.2%), Pseudomonas aeuroginosa (n=14; 7.5%), Acinetobacter baumannii (n=9; 4.8%), Enterobacter spp. (n=9; 4.8%) and Morganella morganii (n=3; 1.6%). E coli colonization during the first day of life was 95.5% (n=43/45), which was relatively higher than in subsequent days. The colonization rate of E coli among low weight babies (≤3 kg) was significantly higher than fully grown neonates (≥4 kg)(P=.03). The prevalence of ESBL and MBL was 15.0% (n=28/188) and 1.6% (n=3/188). The prevalence rates of ESBL in E coli, K pneumoniae, E cloacae, M morganii and E aerogenes were 16.9% (n=22/130), 4.3 % (n=1/23), 60% (n=3/5), 33.3% (n=1/3), and 25% (n=1/4), respectively. All E cloacae with ESBLs and MBLs were resistant to all tested antibiotics including carbapenems.CONCLUSIONWithin the first week of life, the most important determinants of gut enteric bacteria composition in neonates were age in days, body weight, mode of delivery, and type of neonatal feeding. The findings of ESBLs- and MBLs-producing enteric bacteria as neonate-gut colonizers may have wider implication or linkage to prevention of nosocomial and community-acquired infections by these strains.