Epidemiology and Clonal Spread Evidence of Carbapenem-Resistant Organisms in the Center of Care and Protection of Orphaned Children, Vietnam

Objective: To determine the prevalence of colonization and transmission of carbapenem-resistant Gram-negative organisms in order to develop of an effective infection prevention program. Design: Cross-sectional study with carbapenem-resistant organisms (CRO) colonization detection from the fecal specimens of 20 Health Care Workers (HCWs) and 67 residents and 175 random environment specimens from September 2022 to September 2023. Setting: A Care and Protection Centre of Orphaned Children in South of HCM City. Participants: It included 20 HCWs, 67 residents, and 175 randomly collected environmental specimens. Method: Rectal and environmental swabs were collected from 20 HCWs, 67 residents (most of them were children), and 175 environmental specimens. MELAB Chromogenic CARBA agar plates, Card NID, and NMIC-500 CPO of the BD Phoenix TM Automated Microbiology System and whole genome sequencing (WGS) were the tests to screen, confirm CROs, respectively and determine CRO colonization and transmission between HCWs, residents, and the environment. Result: We detected 36 CRO isolates, including 6, 11 and 19 CROs found in 6 HCWs, 10 residents and 19 environments. The prevalence of detectable CRO was 30% (6/20) in HCWs, 14.92% (10/67) in residents, and 10.86% (19/175) in environmental swabs in our study. WGS demonstrated CRO colonization and transmission with the clonal spread of E. coli and A. nosocomialis, among HCWs and residents (children). Conclusion: Significant CRO colonization and transmission was evident in HCWs, residents, and the center environment. Cleaning and disinfection of the environment and performing regular hand hygiene are priorities to reduce the risk of CRO colonization and transmission.

Risk Factors and Prevalence of Mother to New-Born Transmission of Carbapenemase Producing Enterobacteriaceae in Two Hospitals in Yaounde, Cameroon

Background: In African countries, where the burden of neonatal sepsis is the highest, the spread of Carbapenemases Producing Enterobacteriaceae (CPE) in the community, potentially contributing to neonatal mortality, is a public health concern. The transmission routes are not well defined, particularly the possible key role played by pregnant women. The aim of this study was to understand the neonatal acquisition of CPE in Yaounde, Cameroon. Methods: A transversal analytical study was conducted in an urban area. Maternal stool samples during delivery and the first stool from their new-born were collected and cultured to isolate Enterobacteria. After isolation, characterization using API20E identification system, and antibiotic susceptibility testing were performed according to the Antibiogram Committee of the French Society of Microbiology. Carbapenemases detection was done on each carbapenem-resistant strain using the Modified Hodge Test (MHT) and their classification using the synergy tests with different inhibitors. Results: Out of the 55 CPE isolates identified, Escherichia coli was the most encountered bacteria both in mothers (n = 18, 50.00%) and infants (n = 11, 57.89%). Class B and D carbapenemases were found both in mothers and infants. The estimated prevalence of vertical transmission in our study, was 10% (n = 12). Logistic regression showed that CPE carriage in mothers and CPE acquisition in their new-borns were independently associated with the presence of greenish amniotic fluid (OR = 7.33, p 0.0001 in mothers and OR = 4.09, p = 0.0086 in new-borns). Conclusion: Our results highlight the non-negligeable role played by pregnant women in the neonatal acquisition of CPE.

Clinical pharmacists’ involvement in carbapenem antibiotics management at Wenzhou Integrated Hospital

BACKGROUND Carbapenem antibiotics are a pivotal solution for severe infections,particularly in hospital settings.The emergence of carbapenem-resistant bacteria owing to the irrational and extensive use of carbapenems underscores the need for meticulous management and rational use.Clinical pharmacists,with their specialized training and extensive knowledge,play a substantial role in ensuring the judicious use of carbapenem.This study aimed to elucidate the patterns of carbapenem use and shed light on the integral role played by clinical pharmacists in managing and promoting the rational use of carbapenem antibiotics at Wenzhou Integrated Traditional Chinese and Western Medicine Hospital.AIM To analyze carbapenem use patterns in our hospital and role of clinical pharmacists in managing and promoting their rational use.METHODS We performed a retrospective analysis of carbapenem use at our hospital between January 2019 and December 2021.Several key indicators,including the drug utilization index,defined daily doses(DDDs),proportion of antimicrobial drug costs to total hospitalization expenses,antibiotic utilization density,and utilization rates in different clinical departments were comprehensively analyzed.RESULTS Between 2019 and 2021,there was a consistent decline in the consumption and sales of imipenem-cilastatin sodium,meropenem(0.3 g),and meropenem(0.5 g).Conversely,the DDDs of imipenem-cilastatin sodium for injection increased in 2020 and 2021 vs 2019,with a B/A value of 0.67,indicating a relatively higher drug cost.The DDDs of meropenem for injection(0.3 g)exhibited an overall upward trend,indicating an increasing clinical preference.However,the B/A values for 2020 and 2021 were both>1,suggesting a relatively lower drug cost.The DDDs of meropenem for injection(0.5 g)demonstrated a progressive increase annually and consistently ranked first,indicating a high clinical preference with a B/A value of 1,signifying good alignment between economic and social benefits.CONCLUSION Carbapenem use in our hospital was generally reasonable with a downward trend in consumption and sales over time.Clinical pharmacists play a pivotal role in promoting appropriate use of carbapenems.

Risk of transmission of carbapenem-resistant Enterobacteriaceae and related “superbugs” during gastrointestinal endoscopy

To evaluate the risk of transmission of carbapenem-resistant Enterobacteriaceae(CRE) and their related superbugs during gastrointestinal(GI) endoscopy. Reports of outbreaks linked to GI endoscopes contami-nated with different types of infectious agents, includ-ing CRE and their related superbugs, were reviewed. Published during the past 30 years, both prior to and since CRE's emergence, these reports were obtained by searching the peer-reviewed medical literature(via the United States National Library of Medicine's "MEDLINE" database); the Food and Drug Administration's Manu-facturer and User Facility Device Experience database, or "MAUDE"; and the Internet(via Google's search engine). This review focused on an outbreak of CRE in 2013 following the GI endoscopic procedure known as endoscopic retrograde cholangiopancreatography, or ERCP, performed at "Hospital X" located in the sub-urbs of Chicago(IL; United States). Part of the largest outbreak of CRE in United States history, the infection and colonization of 10 and 28 of this hospital's patients, respectively, received considerable media attention and was also investigated by the Centers for Disease Con-trol and Prevention(CDC), which published a report about this outbreak in Morbidity and Mortality WeeklyReport(MMWR), in 2014. This report, along with the results of an independent inspection of Hospital X's in-fection control practices following this CRE outbreak, were also reviewed. While this article focuses primar-ily on the prevention of transmissions of CRE and their related superbugs in the GI endoscopic setting, some of its discussion and recommendations may also apply to other healthcare settings, to other types of flexible endoscopes, and to other types of transmissible infec-tious agents. This review found that GI endoscopy is an important risk factor for the transmission of CRE and their related superbugs, having been recently as-sociated with patient morbidity and mortality following ERCP. The CDC reported in MMWR that the type of GI endoscope, known as an ERCP endoscope, that Hospi-tal X used to perform ERCP in 2013 on the 38 patients who became infected or colonized with CRE might be particularly challenging to clean and disinfect, because of the complexity of its physical design. If performed in strict accordance with the endoscope manufacturer's labeling, supplemented as needed with professional organizations' published guidelines, however, current practices for reprocessing GI endoscopes, which include high-level disinfection, are reportedly adequate for the prevention of transmission of CRE and their related superbugs. Several recommendations are provided to prevent CRE transmissions in the healthcare setting. CRE transmissions are not limited to contaminated GI endoscopes and also have been linked to other reusable flexible endoscopic instrumentation, including broncho-scopes and cystoscopes. In conclusion, contaminated GI endoscopes, particularly those used during ERCP, have been causally linked to outbreaks of CRE and their related superbugs, with associated patient morbidity and mortality. Thorough reprocessing of these complex reusable instruments is necessary to prevent disease transmission and ensure patient safety during GI endos-copy. Enhanced training and monitoring of reprocessing staffers to verify the proper cleaning and brushing of GI endoscopes, especially the area around, behind andnear the forceps elevator located at the distal end othe ERCP endoscope, are recommended. If the ERCPendoscope features a narrow and exposed channel thathouses a wire connecting the GI endoscope's controhead to this forceps elevator, then this channel's com-plete reprocessing, including its flushing with a deter-gent using a procedure validated for effectiveness, is also emphasized.

1β-Methyl Carbapenem 中间体的合成

综述了１β－ＭｅｔｈｙｌＣａｒｂａｐｅｎｅｍ中间体的合成方法，重点强调了如何构筑１位β构型的甲基。参考文献３７篇。

Treatment of sepsis: What is the antibiotic choice in bacteremia due to carbapenem resistant Enterobacteriaceae?

Sepsis is one of the major challenges of today. Although gram-positive bacteria related infections are more prevalent in hospital setting, the highest mortality rate is associated with gram-negative microorganisms especially Enterobacteriaceae. Enterobacteriaceae, including Escherichia coli, Klebsiella spp., Proteus spp., Enterobacter spp. and Serratia spp. Resistance to β-lactams in Enterobacteriaceae is primarily attributed to the production of B-lactamase enzymes with subsequent antibiotic hydrolysis and to a lesser extent by alteration of efflux pump or porins expression. Carbapenem resistant Enterobacteriaceae(CRE) and Acinetobacter baumannii are the most notorious pathogens due to the high incidence of morbidity and mortality especially in the immunocompromised patients in the intensive care unit. The most appropriate antimicrobial therapy to treat CRE is still controversial. Combination therapy is preferred over monotherapy due to its broad-spectrum coverage of micro-organisms, due to its synergetic effect and to prevent development of further resistance. Current suggested therapies for CRE resistance as well as promising antibiotics that are currently under investigation for winning the war against the emerging CRE resistance are reviewed and discussed.

Prevalence of Carbapenem-Resistant Klebsiella Pneumoniae （CRKP） and the Distribution of Class 1 Integron in Their Strains Isolated from a Hospital in Central China

Objective The aim of our study is to investigate the prevalence of Carbapenem-resistant Klebsiella pneumoniae （CRKP） and the genetic characteristics of the class 1 integron in CRKP on multi-drug resistance. Methods Clinical Klebsiella pneumoniae strains were collected from multiple departments of a hospital in central China. CRKP strains were identified among the isolates, and antibiotics susceptibility of CRKP strains was analyzed. The polymerase chain reaction （PCR） was adopted to amplify the class 1 integron variable area. The integron genetic structure was analyzed with enzyme digestion and DNA sequencing technology. The relation between class 1 integron and drug resistance was analyzed statistically. Results Totally 955 strains of Klebsiella pneumoniae were isolated from varied sites of the hospital, and 117（12.3%） of them were identified as CRKP, with a separation rate of 8.9% （26/292） in 2013, 11.3% （38/336） in 2014 and 16.2% （53/327） in 2015, which shows an increasing trend by year. 44.4% （52/117） of CRKP strains were separated from specimen of ICU, and 61.5% （72/117） were from sputum. Over 95% CRKP strains were resistant to ampicillin/sulbactam, aztreonam, imipenem, meropenem Ceftazidme,Cefotaxime,Cefepime,and Piperacillin, while relatively low resistant rates were found in Tigecycline （12.8%） and colistin （35.9%）. The class 1 integron was detected in 77.8% （91/117） of CRKP strains. Class 1 integron of CRKP was significantly correlated with the antibiotic resistance to the tobramycin, gentamicin and amikacin （all P〈0.01）. The gene cassette analysis of variable area of class 1 integron showed that aadA2 accounts for 64.8% （59/91）, aacA4-catB8-aadA1 23.1% （21/91）, and aadA2-dfrA25 12.1% （11/91）. Conclusions CRKP has an increasing trend in a clinical setting in China, and most of them were resistant to multiple antibiotics. Class 1 integron in CRKP has strong ability to capture the genes resistant to aminoglycosides antibiotics from environment, with the aadA2 gene as the most popular one.

Sepsis resulting from Enterobacter aerogenes resistant to carbapenems after liver transplantation

BACKGROUND: Sepsis due to Enterobacter aerogenes (E. aerogenes) is rare after liver transplantation but is also a serious infection that may cause liver abscess. The purpose of this case report is to relate an unusual presentation of liver transplantation to show how successive treatment can be an appropriate option in septic patients after liver transplantation. METHOD: We report on a patient with liver transplantation who developed sepsis due to extended spectrum beta-lactamases and AmpC-producing E. aerogenes. RESULTS: A 39-year-old man had a biliary fistula and then was found to have multiple liver abscesses through abdominal ultrasound and an abdominal computed tomography scan, and carbapenem-sensitive E. aerogenes infection was confirmed. The patient was not successfully treated with conservative treatment consisting of intravenous carbapenems, percutaneous transhepatic cholangial drainage, and biliary stent placement by endoscopic retrograde cholangiopancreatography, so a second liver transplantation followed. Carbapenem-resistant E. aerogenes was detected in bile and blood after a five-week course of carbapenem therapy. The patient developed septic shock and multiple organ dysfunction syndrome. CONCLUSIONS: We first report an unusual case of sepsis caused by E. aerogenes after liver transplantation in China. Carbapenem-resistant E. aerogenes finally leads to uncontrolled sepsis with current antibiotics. We hypothesize that the infection developed as a result of biliary fistula and predisposing immunosuppressive agent therapy. Further research is progressing on the aspect of immunomodulation therapy. (Hepatobiliary Pancreat Dis Int 2009; 8: 320-322)

Study on the Stereoselective Synthesis of Carbapenem Sidechain (2S,4S)-4-Acetylsulphanyl-2-[(S)-1-phenylethylcarbamoyl]-pyrrolidine-1-carboxylic Acid 4-Nitrobenzyl Ester

A stereoselective and economic synthesis of the carbapenem sidechain (2S, 4S)-4-ace-tylsulphanyl-2-[(S)1-phenylethyl-carbamoyl] pyrrolidine-1-carboxylic acid 4-nitrobenzylester was developed. Due to the effect of spatial hindrance, only the (2S,4S) diastereomer 3 wasobtained by coupling 1 and the inexpensive racemic 2 catalyzed by EEDQ.

Patient Demographics and Characteristics of Infection with Carbapenem-Resistant <i>Acinetobacter baumannii</i>in a Teaching Hospital from the United States

A characterization of the clinical demographic features of patients with infection caused Acinetobacter baumannii, and the antibiotyping of the isolates recovered from these patients was undertaken, with a special reference to carbapenem-resistant variants, and their risk factors. This study was conducted retrospectively from January 2010 to March 2011 at a 616-bed tertiary care university hospital. Sixty-four patients were identified. Clinical and microbiological data were analyzed for risk factors and demographic features to derive relative risk and odds ratio. We identified 100 A. baumannii from 64 patients during 15 months period. Significant risk factors were working age (18 - 60 years), male gender, hospital stay (>1 week but Pseudomonas aeruginosa, and Klebsiella pneumoniae were the significant co-infecting agents. The antibiogram demonstrated multidrug resistance in a majority of the isolates. Relative risk associated with ventilator, diabetes, and surgery was higher in repeat isolates than in first isolates and were multidrug resistant. Repeat isolates were more resistant that the first isolates to most anti-acinetobacter agents, but the overall crude mortality was not significant during this study period, and couldn’t correlated to the choice of treatment. In conclusion, a resistance against all clinically used carbapenems, and colistin is rapidly increasing in repeat isolates of A. baumannii;leaves narrow therapeutic options to treat multidrug-resistant and pandrug-resistant A. baumannii infection. For the first time we report rising incidence of colistin resistance by 20 percent in repeat isolates, and is worrisome for healthcare centers. A combination therapy should be adopted to treat such infection to avoid the emergence of colistin-resistant phenotypes in the United States.

Molecular Detection of Carbapenemase Genes in Extensive Drug Resistant Acinetobacter baumannii Clinical Isolates from ICU Patients, Khartoum

Background: The emergence of carbapenemase producing Acinetobacter baumannii is increasingly reported nowadays and constitutes a major problem to the intensive care unit (ICU) patients with notable extensive-drug resistance ability. The study investigates carbapenemase producing A. baumannii strains exhibiting an extensively drug-resistant (XDR) phenotype, isolated from ICU patients in Khartoum. Methods: A total of 100 nonduplicate Gram-negative coccobacilli strains were obtained from microbiology laboratory of ICU patients’ clinical isolates. Molecular identification of A. baumannii was performed by targeting 16S rRNA gene using specifically designed primers. Then, XDR strains were determined by susceptibility testing (disc diffusion). For detection of carbapenemase genes Polymerase chain reaction (PCR) was carried out. Result: Of 100 ICU clinical isolates, 38 (38.0%) was confirmed A. baumannii strains, those strains showed 100% carbapenem resistance and 60.5% extensive drug resistance to the antibiotics tested. The frequency of carbapenemase producer was 57.9% (22/38) of carbapenem resistance A. baumannii (CRAB). The most common carbapenemase associated with resistance was blaOXA gene followed by blaNDM and blaGES A. baumannii isolates. The co-occurrence of blaOXA-48-like and blaNDM, blaOXA-23-like and blaOXA-51, and blaNDM-1 and blaOXA-51 was detected in 22.7%, 18.2% strains and 4.5% respectively. A unique characteristic of our findings was the coharbouring of the genes blaNDM-1, blaOXA-23-like, blaOXA-51 and blaOXA-143 in 9.1% strains (2/22), and this was the first report in the Khartoum city, Sudan. Conclusion: We have demonstrated for the first time a high prevalence of XDR-carbapenemase producing A. baumannii clinical isolates from ICU patients in Khartoum. Also an emergent blaOXA-143 was reported as High-Risk Clones. This highlights the routine mentoring of XDR-carbapenemase producing A. baumannii to avoid clone dissemination in our region hospitals.

Emerging Carbapenem-Resistant <i>Enterobacter cloacae</i>Producing OXA-48-, VIM- and IMP-Type-<i>β</i>-Lactamases in Eastern Cape Hospitals in South Africa

Introduction: Enterobacter cloacae strains have been isolated from Eastern Cape hospitalised patients. Methodology: We have molecularly characterised blaOXA-48-, blaIMP- and blaVIM-expressing E. cloacae isolates demonstrating resistance to carbapenems from five hospitals by multilocus sequence typing. Organism identification and antimicrobial susceptibility testing was done using automated systems and the isolates were screened for carbapenemases using either conventional or real-time PCR and then typed using multilocus sequence typing. Further characterisation of IMP-type-producing E. cloacae isolates, an unusual occurrence in South Africa, was performed by pulsed-field gel electrophoresis. Results and Conclusion: Twenty-five E. cloacae isolates from 24 patients were investigated. Eighteen (72%) isolates harboured either one of the following genes: blaIMP, blaVIM or blaOXA-48. Multilocus sequence typing data and pulsed-field gel electrophoresis showed that several strains from the same geographical region and hospitals were genetically related.

Solid-Phase Total Synthesis of 1-β-Methylcarbapenem

A 1-b-methylcarbapenem analogue 6 was synthesized on polystyrene-diethylsilane resin (PS-DES) using 2-azetidinone bearing with 2-oxazolidone chiral auxiliary as starting material.

Relationship of multidrug-resistant gene and extended-spectrum carbapenem-resistance in Staphylococcus aureus

The aim of this study was to determine the relationship between phenotypic antimicrobial susceptibility patterns and extended-spectrum,carbapenem-resistance genes.A total of 109 clinical Staphilococcus aureus strains were subjected to 19 antimicrobial susceptibility tests.Resistance to methicillin(mecA),penicillin(blaTEM),and tetracycline(tetM)was detected.We compared the presence of the blaTEM genes with extended-spectrum,carbapenem-related genes and identified the types of SCCmec genes.Of 109 clinical S.aureus strains,62(56.88%)had methicillin resistance and 60 strains carried mecA.The prevalence of blaTEM and tetM genes was 81.65%and 37.61%,respectively.The most predominant SCCmec type was SCCmec type Ⅱ 28/60(46.67%),in 60 mecA-positive methicillin-resistant S.aureus(MRSA)isolates.The SCCmec prevalence rates were type ⅣA 30.00%(18/60),type Ⅳb 8.33%(5/60),type Ⅳd 6.67%(4/60),and non-typable 8.33%(5/60).Sixty of the 109(55.05%)MRSA isolates were positive for extended-spectrum carbapenems(31/60)(51.67%),cephalosporins 40/60(66.67%)and carbapenems 31/60(51.67%).The predominant SCCmec type II demonstrated more carbapenem-resistance than the ⅣA,Ⅳb and Ⅳd types.

Transmission of Carbapenem Resistance Between Human and Animal NDM-Positive Escherichia coli Strains

Although carbapenem use is prohibited in animals in China,carbapenem-resistant Escherichia coli(CREC),especially New Delhi metallo-β-lactamase(NDM)-producing strains,are widely prevalent in foodproducing animals.At present,the impact of livestock-associated CREC strains on human populations at the national level is unknown.Here,we conduct a retrospective cross-sectional study to investigate the prevalence of CREC from clinical settings across 22 Chinese provinces or municipalities and analyze anthropogenic factors associated with their presence.We also ascertain the blaNDMand blaKPCabundance among pig and chicken farms and present a detailed genomic framework for CREC of animal and human origin.Overall,631/29799(2.1%)clinical Escherichia coli(E.coli)isolates were identified as CREC.Multivariable analysis revealed that being male,an age below 1,an age between 13 and 18,provinces with greater chicken production,and provinces with higher pig production were associated with higher odds of CREC infection.In general,73.8%(n=45/61)of pig farms and 62.2%(n=28/45)of chicken farms had a blaNDMabundance of 1×10^(-5)to 1×10^(-3)and 1×10^(-3)to 1×10^(-2),respectively.Among all the Chinese NDM-positive E.coli(n=463)available at the National Center for Biotechnology Information(NCBI),the genomic analysis revealed that blaNDM-5and Inc X3 were the predominant carbapenemase gene-plasmid combination,while a highly homogeneous relationship between NDM-positive isolates from humans and animals was demonstrated at the plasmid and core genome levels.All the findings suggest frequent CREC transmission between humans and animals,indicating that further discussions on the use of antibiotics in animals and humans are needed,both in China and across the globe.

Trends in the Annual Incidence of Carbapenem Resistant among Gram Negative Bacilli in a Large Teaching Hospital in Makah City, Saudi Arabia

Objective: To detect the prevalence of carbapenem resistance among Gram negative bacilli at the Al-Noor Specialist Hospital in the western part of Saudi Arabia. Materials and Methods: This study was conducted in the Microbiology department, Al-Noor Specialist Hospital, Makah city, Saudi Arabia. The clinical samples were collected from admitted patients in the wards, Intensive Care Units (ICUs), urology unit and surgery unit, these samples included blood, urine, sputum, pus and wound. The identification and antibiotic susceptibility testing of all bacterial isolates were performed via the Vitek 2 Compact System. Results: Out of 4803 Gram negative bacterial bacilli were isolated, the prevalence rate of carbapenem resistance among these isolates was 2797/4803 (58.23%), and sensitivity rate was 2006/4803 (41.77%) of the total isolates. The rate of resistance to carbapenem was among Acinetobacter baumannii 1710 (99.13%), followed by Pseudomonas aeruginosa 575 (62.4%), Klebsiella pneumoniae 459 (38%) and Escherichia coli 56 (5.59%). The trend of carbapenem resistance among Gram negative bacterial isolates from 2013-2015 was 53.99%, 59.88% and 61.43% respectively. Conclusion: A. baumannii rec-orded, the highest rate of carbapenem resistance through three year, 98.19%, 99.48% and 99.81% respectively and the lowest rate of resistance recorded with E. coli, 4.63%, 5.79% and 6.31% respectively.

A Case of Carbapenem Resistant Non-K1/K2 Serotype <i>Klebsiella pneumoniae</i>Liver Abscess

Klebsiella pneumoniae liver abscess (KPLA) has been described as an invasive syndrome with extrahepatic complications. The majority of KPLA is caused by capsular serotype K1 and K2 isolates. We report a case of carbapenem resistant Klebsiella pneumoniae liver abscess. The patient initially presented with infected right above-the-knee amputation and was later found with a large liver abscess. Initial antimicrobial susceptibility showed carbapenem resistant K. pneumoniae (CRKP). Further molecular workup revealed that the isolate was a less virulent non-K1/K2 serotype, and both rmpA and kfu genes were negative. The lack of outer membrane porins likely contributed to the carbapenem resistance. To our knowledge, this is a first reported case of carbapenem resistant, non-K1/K2 serotype K. pneumoniae liver abscess in the United States.

Low Prevalence of Carbapenem Resistance in Clinical Isolates of Extended Spectrum Beta Lactamase (ESBL) Producing <i>Escherichia coli</i>in North Central, Nigeria

Extended Spectrum Beta Lactamase (ESBL) producing Escherichia coli is a global cause of life threatening infections. We determined the presence of ESBL and carbapenemase production in clinical isolates of E. coli and their antibiotic susceptibility. Clinical isolates of community and hospital acquired E. coli from 220 patients seen at a tertiary hospital were evaluated. Antibiotic susceptibility testing was by the modified Kirby-Bauer protocol while ESBL production was determined by the Double Disk Synergy Test (DDST). Carbapenem resistance was confirmed by the Modified Hodge Test. Of the 220 isolates, 122 (55.5%) were from females;41 (18.6%) were ESBL positive. About 90% of the ESBL producing isolates were resistant to nine of the 15 antimicrobial agents tested. However, only one (2.4%) of the 41 ESBL producing isolates exhibited carbapenem resistance. The ESBL negative isolates were susceptible to Meropenem (100%), Cefepime (97.8%), Ceftriaxone (96.6%) and Cefotaxime (96.6%). All the ESBL producing isolates harbored detectable plasmids with sizes ranging from 2322 to 23,130 base pairs. Our findings show that although multidrug resistant ESBL producing E. coli are prevalent in both the hospital and the community in this environment, carbapenem resistance is still low. We recommend that institutions develop guidelines for the early phenotypic detection of ESBLs and carbapenem resistance.

Study of OmpK35 and OmpK36 Expression in Carbapenem Resistant ESBL Producing Clinical Isolates of Klebsiella pneumoniae

Background: Carbapenem resistant extended spectrum β-lactamase (ESBL) producing Klebsiella pneumoniae (K. pneumoniae) is increasing worldwide. Carbapenem resistance (CR) has been attributed not only to production of carbapenemases but also to permeability barriers due to outer membrane proteins (OmpK35 and OmpK36) disruption. Objective: Phenotypic detection of CR among ESBL producing K. pneumoniae isolates, followed by the evaluation of the role of ompK35 and ompK36 gene expression among carbapenem resistant K. pneumoniae (CR-KP) isolates. Methods: 100 ESBL producing K. pneumoniae isolates were included in this study. Minimum inhibitory concentration (MIC) of imipenem was performed for all isolates by broth microdilution method. For CR-KP isolates, phenotypic detection of K. pneumoniae carbapenemase (KPC), metallo-β-lactamase (MBL) and AmpC enzymes was performed followed by Realtime qRT-PCR to detect and quantify ompK35 and ompK36 gene expression. Results: 42% of our isolates were carbapenem resistant, and all of them were KPC producers either singly or in combination with MBL and/or AmpC production. Reduced expression of both ompK35 and ompK36 was detected in (52.38%) of CR-KP isolates, while reduced expression of ompK36 or ompK35 alone was found in (2.38%) and (33.33%) respectively. Twenty of 42 CR-KP isolates (47.62%), showing reduced ompK35 and ompK36 expression, exhibited high level resistance (HLR) (>32 μg/ml) to imipenem. There was a significant correlation between reduced expression of ompK36 and increase MIC values (p < 0.05). The combined production of MBL or AmpC together with reduced expression of ompK35 and/or ompK36 resulted in significant increase in imipenem MIC (p < 0.05). Conclusion: The combined OmpK35/OmpK36 loss resulted in HLR. However OmpK36 seems to play a major role in those strains. Imipenem MIC was markedly increased among K. pneumoniae showing carbapenemase and/or AmpC production together with loss of OmpK35 and/or OmpK36.

Detection and Characterization of β-Lactamase Encoding Genes in Carbapenem Non-Susceptible Gram-Negative Bacteria and Susceptibility of Isolates to Ceftazidime-Avibactam at a New York City Community Hospital

A surveillance study was undertaken to identify prominent β-lactamase encoding genes in 131 carbapenem non-susceptible gram-negative clinical isolates at a New York City community hospital. KPC carbapenemases were detected in 89% of Enterobacteriaceae as well as additional TEM, SHV, and CTX-M class A enzymes. OXA-23 and OXA-24 were the prevalent class D carbapenemases identified in Acinetobacter species. One OXA-23 in M. morganii and one OXA-48 in K. pneumoniae were also identified. Among class C β-lactamases CMY, ACT/MIR, DHA, and FOX were detected. The in vitro activity of ceftazidime-avibactam by E-test methodology was tested with minimal inhibitory concentrations (MIC) of ≤3 μg/ml for 97.8% of all Enterobacteriaceae, MIC50/90 of 16/>256 μg/ml for carbapenem non-susceptible Acinetobacter, and 3/6 μg/ml for carbapenem non-susceptible Pseudomonas aeruginosa. Periodic surveillance of isolates to characterize current and emerging β-lactamase genotypes present in local isolates may help identify outbreak situations, provide assistance to infection control and antibiotic stewardship programs, and potentially improve patient outcomes.