Molecular surveillance and clinical outcomes of carbapenem-resistant Escherichia coli and Klebsiella pneumoniae infections

Hospital-Acquired Infections Caused by Carbapenem-Resistant Enterobacteriaceae: An Observational Study

Worldwide, hospital-acquired infections (HAIs) are continuously rising within healthcare settings, leading to high mortality and morbidity rates. Many hospitals have reported the spread of carbapenemases globally, specifically within the E. coli and K. pneumoniae species. This study was aimed at analyzing the state of hospital-acquired, carbapenem-resistant E. coli and K. pneumoniae in the United Kingdom between 2009 and 2021. Moreover, the study analyzed the most efficacious approaches to patient management for controlling the carbapenem-resistant Enterobacteriaceae (CRE) spread. Initially, 1094 articles were identified as relevant for screening, and among them, 49 papers were eligible for full-text screening, with a total of 14 articles meeting the inclusion criteria. The information was recorded from published articles through PubMed, the Web of Science, Scopus, Science Direct, and the Cochrane library and was used to search for hospital-acquired carbapenem-resistant E. coli and K pneumoniae in the UK between 2009 and 2021, in order to evaluate the spread of CRE in hospitals. The total number of carbapenem-resistant E. coli was 1083 and this was 2053 for carbapenem-resistant K. pneumoniae in more than 63 UK hospitals. KPC was the dominant carbapenemase produced by K. pneumoniae. The results showed that the treatment options considered depended on the type of carbapenemase produced; K. pneumoniae showed more resistance to a treatment options, i.e., Colistin, than the other carbapenemase. The current state of the UK is at minimal risk for a CRE outbreak; however, appropriate treatment and infection control measures are highly required to prevent this CRE spread at the regional and global levels. The present study findings have an important message for physicians, healthcare workers, and policymakers about hospital-acquired carbapenem-resistant E. coli and K. pneumoniae spread and approaches to patient management.

In Vitro Activity of Single and Combined Antibiotics against Carbapenem Resistant Enterobacteriaceae Clinical Isolates in Relation to their Resistance Genes

Background: Mortality due to infection with carbapenem-resistant Enterobacteriaceae (CRE) is reported globally and carbapenemase production is the main mechanism of resistance in these isolates. The detection and treatment of carbapenemase-producing Enterobacteriaceae (CPE) is a major challenge in health care facilities. Objectives: The aim of the current study was to evaluate the in-vitro effect of different single and combined antibiotic agents against CRE clinical isolates. Methodology: Fifty CRE isolates were detected using disk diffusion test as a screening test. Species identification and antibiotic susceptibility testing was done using Vitek 2 system. Carbapenemase enzyme production was confirmed by Carba NP test. Multiplex PCR was done to detect carbapenem resistance genes. Antibiotics were tested in the form of single agents (colistin and tigecycline) and combined (tigecycline/ colistin, doripenem/ colistin and dual carbapenem therapy (ertapenem and doripenem) against CRE isolates using E-test method. Results: Most of the CRE isolates were K. pneumoniae, 68%, followed by E. coli, 22%, S. marcescens, 4%, E. cloacae, 4% and C. freundii, 2%. CPE was confirmed in 46 isolates by multiplex PCR; blaNDM-like was the main carbapenem resistance gene in (84%) of the isolates, followed by blaOXA-48-like (6%) and blaKPC-like (2%). Carba NP test detected 90% of CPE isolates. Single use of colistin and tigecycline showed 100% sensitivity against all tested CRE isolates except in blaNDM-like (83%).  Combination of colistin/tigecycline showed synergetic activity in 18% of CRE that was correlated to their carbapenemase R genes showing a significant increase in blaOXA-48-like and blaKPC-like positive isolates (100%) compared to blaNDM-like (7%). Other combinations showed indifferent effect whereas antagonism was not detected in any of the tested combinations. Conclusions: blaNDM-like is the main carbapenemase-producing gene detected among our CPE isolates followed by blaOXA-48-like. Colistin and tigecycline are still effective when used as single agents, and may offer effective treatment options when used in combination for CRE infections. Characterization of carbapenemases is crucial in determining treatment options. There is urgent demand for the development of novel therapeutic agents against NDM-producing CPE isolates.

Klebsiella pneumoniae Harboring Carbapenemase Genes in Taiwan: Its Evolution over 20 Years, 1998-2019

Klebsiella pneumoniae (K. pneumoniae) is an important pathogen causing various types of human infections in Taiwan. Carbapenemases have increasingly been reported in Enterobacterales in the past two decades. Carbapenemase-producing K. pneumoniae (CPKP), a major resistance concern that has emerged during the last decade, has become a global threat, with its related infections associated with high morbidity and mortality; however, therapeutic options for CPKP-associated infections are limited. Carbapenemases - including K. pneumoniae carbapenemases (KPC)-2, New Delhi metallo-β-lactamase (NDM)-1, Verona integron-encoded metallo-β-lactamase (VIM)-1, imipenemase (IMP)-1, and oxacillinase (OXA)-48 - have been reported worldwide, with a marked prevalence in different countries or areas of the world. Understanding the epidemiology of carbapenemase producers is important for the prevention of their expansion. This review examined the evolution of CPKP in the last two decades to better understand the role of CPKP in Taiwan. It discovered that the endemicity has changed from IMP-8, NDM-1 and VIM-1 to the most common KPC-2 and rapidly emerging OXA-48. Resistance epidemiology, genetic background, virulence factors, therapy, and outcomes are discussed in this paper.

Detection of OXA-48 Gene in Carbapenem-Resistant Escherichia coli and Klebsiella pneumoniae from Urine Samples

INTRODUCTION

Resistance to carbapenem in Gram-negative bacteria is attributable to their ability to produce carbapenemase enzymes. The main objective of this study was to detect the presence of blaOXA-48 genes in carbapenem-resistant uropathogenic Escherichia coli and Klebsiella pneumoniae isolated from urine samples from patients attending Alka Hospital, Jawalakhel, Lalitpur, Nepal.

METHODS

A total of 1013 mid-stream urine samples were collected from patients with suspected urinary tract infection (UTI) between April and September 2018. The identified isolates underwent antibiotic susceptibility testing using the modified Kirby-Bauer disc-diffusion method. Phenotypic carbapenemase production was confirmed by the modified Hodge test, and the blaOXA-48 gene was detected using conventional polymerase chain reaction.

RESULTS

Out of 1013 urine samples, 15.2% (154/1013) had bacterial growth. Among the isolates, 91.5% (141/154) were Gram-negative bacteria, and E. coli was the most common bacterial isolate (62.9%; 97/154), followed by K. pneumoniae 15.6% (24/154). Among 121 bacterial isolates (97 E. coli isolates and 24 K. pneumoniae isolates), 70.3% (52/121) were multidrug-resistant E. coli and 29.7% (22/121) were multidrug-resistant K. pneumoniae. In addition, 9.1% (11/121) were carbapenem resistant (both imipenem and meropenem resistant). Development of multidrug resistance and development of carbapenem resistance were significantly associated (p<0.05). Of the 11 carbapenem-resistant isolates, only seven were carbapenemase producers; of these, 28.6% (2/7) were E. coli, 72.4% (5/7) were K. pneumoniae and 42.8% (3/7) had the blaOXA-48 gene. Of the three bacterial isolates with the blaOXA-48 gene, 33.3% (1/3) were E. coli and 66.7% (2/3) were K. pneumoniae.

CONCLUSION

One in ten isolates of E. coli and K. pneumoniae were carbapenem resistant. Among carbapenem-resistant isolates, one-third of E. coli and two-thirds of K. pneumoniae had the blaOXA-48 gene. OXA-48 serves as a potential agent to map the distribution of resistance among clinical isolates.

Detection of Carbapenem-Resistant Genes in Escherichia coli Isolated from Drinking Water in Khartoum, Sudan

Waterborne Escherichia coli are a major reservoir of antimicrobial resistance (AMR). Carbapenem-resistance, especially when mediated by transferable carbapenemase-encoding genes, is spreading worldwide and causing dramatically limiting treatment options. In our country, studies for the detection of carbapenem resistance in drinking water do not exist; therefore, this work was carried out to determine the prevalence of carbapenem-resistant genes “bla_KPC, bla_IMP, bla_NDM, bla_SPM, bla_VIM, and bla_OXA-48” among Escherichia coli isolated from drinking water in Khartoum, Sudan. A total of forty-five E. coli bacteria were isolated from different sources of drinking water. Antimicrobial susceptibility testing was performed using imipenem (10 mg/disc), gentamicin (10 mg/disc), ceftriaxone (30 mg/disc), ciprofloxacin (5 mg/disc), chloramphenicol (30 mg/disc), and tetracycline (30 mg/disc). “Sensitive” or “resistant” patterns of E. coli were judged using antibiotic minimum inhibitory concentration (MIC). Bacterial genomic DNA was extracted by the boiling method, and then multiplex polymerase chain reaction was performed to detect the carbapenemase genes (bla_KPC, bla_IMP, bla_NDM, bla_SPM, bla_VIM, and bla_OXA-48). Multiplex PCR assays confirmed the presence of carbapenemase genes in 28% of all water isolates. OXA-48 gene was the most predominant gene, detected in 15.5% of the isolates. The bla_KPC and bla_SPM genes were also detected in 4.4% and 8.8% of the isolates, respectively. However, the isolates were negative for bla_NDM, bla_VIM, and bla_IMP genes. The isolates showed a high rate of tetracycline resistance (97.7%), followed by gentamicin (57.7%), ciprofloxacin (46.6%), ceftriaxone (35.5%), and chloramphenicol (31.1%). In conclusion, this study confirmed for the first time the presence of E. coli carried carbapenem-resistant genes in the drinking water of Khartoum state, Sudan. These isolates commonly carried OXA-48 (7/45), followed by SPM (4/45) and KPC (2/45).

Potentials of Actinomycetes from Reserved Environments as Antibacterial Agents Against Drug-Resistant Clinical Bacterial Strains

BACKGROUND

Increased antibiotic resistant properties of pathogens has led to a pronounced search for new effective antibiotics from microbes in diverse ecological niches. This study focused on isolating actinomycetes from soil of reserved areas and profiling them for antibacterial potentials.

METHODS

The isolates (IS-2, IS-4, IS-6, IS-10, IS-14) were assessed for antagonistic activity against ten multi-drug resistant bacterial strains (Gram positive and negative) by cross streak and well diffusion methods.

RESULTS

During the primary screening, four of the isolates showed good antagonistic activity against the test strains. Notably, all the bacterial strains except Pseudomonas aeruginosa responded sensitively to at least one of the actinomycetes screened. The crude extracts of the secondary metabolites of the four actinomycetes (IS-2, IS-4, IS-6, IS-10) with considerably significant antagonistic activities inhibited the growth of all the bacterial strains efficiently. All the test bacterial strains were sensitive to at least one of the extracts at a concentration of 100µg/ml. The minimum inhibitory concentration of the extracts against the isolates ranged from 12.5 - 25µg/ml. The crude extracts of IS-4 and IS-6 identified as Streptomyces glauciniger NBRC 100913 and Streptomyces griseoplanus NRRL-ISP 5009 by I6s rRNA sequencing, showed higher antibacterial activities against the bacterial strains. Significantly, the ethyl acetate crude extract of the actinomycetes demonstrated better antibacterial activities than the standard antibiotics (ofloxacin, amoxicillin/clavulanate, cefuroxime and ceftriaxone).

CONCLUSION

This study reports remarkable anti-MRSA activities as well as broad spectrum antibacterial potentials of extracts of Streptomyces spp. worthy of further exploration.

A matched case-control study to assess the carbapenem-resistant Enterobacteriaceae infections among hospitalized children at King Fahad Medical City, Riyadh, Saudi Arabia

OBJECTIVES

To identify risk factors associated with carbapenem-resistant Enterobacteriaceae (CRE) infections among hospitalized children at King Fahad Medical City, Riyadh, Saudi Arabia.

METHODS

A retrospective matched case-control study was conducted in pediatric patients with CRE infection at King Fahad Medical City, Riyadh, Saudi Arabia between January 2016-2017.

RESULTS

During the study period, 19 CRE cases and 37 controls were identified for analysis. Children  ≤17 years (mean age±SD for cases was 43.9±46 months and controls was 29.2±52.2 months) were included in the study. Several factors associated with CRE infections were identified, which included, central venous catheter (CVC) line placement (p=0.023; confidence interval [CI]: 0.97-85.77), recent surgical procedures (p=0.006; CI: 1.30-9.28), invasive procedures (p greater than 0.001; CI: 1.98-21.18), use of prior antibiotics (p=0.008; CI: 1.38-24.62), and carbapenem exposure in the past 3 months (p=0.004; CI: 1.09-12.20). Among the cases, Klebsiella pneumonia was the most commonly identified (47%) followed by Escherichia coli (31%). Carbapenem-resistant Enterobacteriaceae was associated with increased comorbidities and prolonged hospitalization however, no mortalities were reported.

CONCLUSION

This study identified prior antibiotic exposure, recent surgery and the use of invasive procedures as significant risk factors for colonization or infection with CRE. Also, the need for public awareness, continuing education for healthcare professionals, optimum use of invasive devices, enhanced surveillance, and antimicrobial stewardship are highlighted here which can limit CRE transmission in healthcare facilities.

Carbapenem-Resistant Enterobacteriaceae Infections: Taiwan Aspects

Carbapenem-resistant Enterobacteriaceae (CRE), a major resistance concern emerging during the last decade because of significantly compromising the efficacy of carbapenem agents, has currently become an important focus of infection control. Many investigations have shown a high association of CRE infections with high case-fatality rates. In Taiwan, a few surveys observed that a significant proportion (29–47%) of the CR-Klebsiella pneumoniae isolates harbored a plasmidic allele encoding K. pneumoniae carbapenemases (KPC, especially KPC-2). A significant increase in the number of oxacillinase (OXA)-48-like carbapenemases among CR-K. pneumoniae isolates was observed between 2012 and 2015. By striking contrast, isolates of CR-Escherichia coli and CR-Enterobacter species in Taiwan had a much lower percentage of carbapenemase production than CR-K. pneumoniae isolates. This differs from isolates found in China as well as in the India subcontinent. Apart from the hospital setting, CRE was also cultured from the inpatients from communities or long-term care facilities (LTCF). Therefore, implementation of regular CRE screening of LTCF residents, strict disinfectant use in nursing homes and hospital settings, and appropriate control of antibiotic prescriptions is suggested to alleviate the spread of clinical CRE isolates in Taiwan. Although there are some promising new antibiotics against CRE, such as ceftazidime-avibactam, meropenem-vaborbactam, aztreonam-avibactam and cefiderocol, these agents are not available in Taiwan currently. Therefore, in order to effectively decrease case-fatality rates among patients with the infections owing to carbapenemase-producing CRE isolates, combination antibiotic schemes, including colistin (or amikacin) and/or tigecycline in combination with an anti-pseudomonal carbapenem agent, remain the mainstay for treating clinical CRE infections.

Whole genome sequence revealed the fine transmission map of carbapenem-resistant Klebsiella pneumonia isolates within a nosocomial outbreak

Background

Carbapenem-resistant Klebsiella pneumoniae (CRKP) is a major cause of nosocomial infections worldwide. The transmission route of CRKP isolates within an outbreak is rarely described. This study aimed to reveal the molecular characteristics and transmission route of CRKP isolates within an outbreak of nosocomial infection.

Methods

Collecting case information, active screening and targeted environmental monitoring were carried out. The antibiotic susceptibility, drug-resistant genes, molecular subtype and whole genome sequence of CRKP strains were analyzed.

Results

Between October and December 2011, 26 CRKP isolates were collected from eight patients in a surgical intensive care unit and subsequent transfer wards of Beijing Tongren hospital, China. All 26 isolates harbored bla_KPC-2, bla_SHV-1, and bla_CTX-M-15 genes, had the same or similar pulsed-field gel electrophoresis patterns, and belonged to the sequence type 11 (ST11) clone. By comprehensive consideration of genomic and epidemiological information, a putative transmission map was constructed, including identifying one case as an independent event distinct from the other seven cases, and revealing two transmissions starting from the same case.

Conclusions

This study provided the first report confirming an outbreak caused by K. pneumoniae ST11 clone co-harboring the bla_KPC-2, bla_CTX-M-15, and bla_SHV-1 genes, and suggested that comprehensive consideration of genomic and epidemiological data can yield a fine transmission map of an outbreak and facilitate the control of nosocomial transmission.

Factors associated to prevalence and treatment of carbapenem-resistant Enterobacteriaceae infections: a seven years retrospective study in three tertiary care hospitals

Background

The increasing incidence of carbapenem-resistant Enterobacteriaceae (CRE), has resulted in a difficult problem in the current clinical anti-infective treatment. We performed a retrospective analysis of prevalence and treatment for CRE infections patients.

Methods

This study was conducted in three tertiary care hospitals from January 1, 2010 to December 30, 2016. Baseline data, treatment, and outcomes were collected in patients with ventilator-associated bacterial pneumonia (VABP), bacteremia, complicated urinary tract infection (cUTI)/acute pyelonephritis (AP), hospital-acquired bacterial pneumonia (HABP), superficial wound infection (SWI), biliary tract infection (BTI), deep wound infection (DWI) and sterile body fluids infection (SBFI) due to CRE.

Results

One hundred twenty-four cases of CRE infection were identified: 31 VABP, 22 bacteremia, 18 cUTI/AP, 16 HABP, 16 SWI, 9 BTI, 7 DWI and 5 SBFI. The patient population had significant immunocompromised (33 of 124, 26.6%) and severe sepsis (43 of 124, 34.7%). The most common CRE pathogens were Klebsiella pneumoniae (84 of 124, 67.7%) and Enterobacter cloacae (24 of 124, 19.4%). And the production of IMP-type carbapenemase was the main antibiotic resistance mechanism. The majority of patients to take monotherapy for empiric therapy and dual therapy for direct treatment. Outcomes were universally poor (28-day mortality was 22.6%, 28 of 124) across all sites of infection.

Conclusions

We identified a large number of cases of CRE infection in 7 years from different parts, most of these pathogens have been confirmed to produce IMP-type carbapenemases. The retrospective analysis of cases of such bacterial infections will help to control future infections of these pathogens. Despite the high mortality rate, we still found that the selection of quinolone antibiotics can be effective in the treatment of CRE producing IMP type enzymes.

Mortality due to KPC carbapenemase-producing Klebsiella pneumoniae infections: Systematic review and meta-analysis: Mortality due to KPC Klebsiella pneumoniae infections

INTRODUCTION

KPC carbapenemase-producing Klebsiella pneumoniae (KPC-KP) has become a major public health challenge. Accordingly, this study sought to use a systematic review of the scientific literature to ascertain the mortality of KPC-KP infection, and analyze such mortality by country, year of publication, hospital ward, and type of interpretation used to define carbapenem resistance.

METHODOLOGY

A search without language restrictions was made of the MEDLINE, CENTRAL, EBSCO, LILACS and EMBASE databases from 1996 through June 2017, to locate all studies which had determined the existence of KPC-KP infection. We then performed a meta-analysis of all studies that reported KPC-KP infection-related mortality, and analyzed mortality by subgroup in accordance with standard methodology.

RESULTS

A total of 51 papers were included in the systematic review. From 2005 through 2017, data on KPC-KP infection were reported in 5124 patients, with an average of 465 patients per year. The most widely studied type of infection was bacteremia (28∙0%). The meta-analysis showed that overall mortality for the 37 studies was 41.0% (95%CI 37.0-44.0), with the highest mortality rates being observed in oncology patients, 56.0% (95%CI 38.1-73.0), and Brazil, 51.3% (95%CI 43.0-60.0).

CONCLUSION

KPC-KP infection-related mortality is high, is manifested differently in some countries, and is highest among oncology patients.

Study on MICs of Tigecycline in Clinical Isolates of Carbapenem Resistant Enterobacteriaceae (CRE) at a Tertiary Care Centre in North India

INTRODUCTION

Members of family Enterobacteriaceae are the most common Gram-negative bacteria isolated from clinical samples. Those Enterobacteriaceae which have acquired resistance to all β-lactams antibiotics including the carbapenems are considered as Carbapenem Resistant Enterobacteriaceae (CRE). These CRE isolates are often resistant to most other classes of antimicrobials as well, making their treatment a great challenge. Tigecycline is one of the last resort antimicrobials against such multidrug resistant bacteria. Decreased tigecycline susceptibility mediated by efflux pump systems is being reported in clinical strains of Enterobacteriaceae. Minimum Inhibitory Concentration (MIC) data would prove useful in managing infections by these multidrug resistant bacteria and optimizing use of tigecycline.

AIM

To evaluate the MIC values of tigecycline against carbapenem resistant Escherichia coli and Klebsiella pneumoniae isolates.

MATERIALS AND METHODS

This prospective study was carried out from January 2015 to December 2015 at the Department of Microbiology, Era's Lucknow Medical College and Hospital (ELMCH), Lucknow, Uttar Pradesh, India. Antimicrobial susceptibility by disk diffusion (Kirby-bauer) was done for 491 E. coli and K. pneumoniae strains isolated from 1606 samples collected from patients admitted in various wards and ICUs. Imipenem, meropenem and ertapenem 10 μg disks were used for testing of sensitivity to carbapenems. In all isolates, Tigecycline 15 μg (Hi-Media) disk was used to screen for tigecycline resistance. In CRE isolates, MICs of tigecycline were determined by E-test (Ezy MIC TM TG strips, Hi Media) and interpreted using European Committee on Antimicrobial Susceptibility Testing (EUCAST) 2016 guidelines.

RESULTS

Out of 491 isolates tested, 186 (37.9%) were found to be CRE showing resistance to at least one of the three carbapenems tested and these included 99 E.coli and 87 K. pneumoniae. Sensitivity pattern of these two bacterial isolates shows a high level of resistance to most classes of antimicrobials. MIC testing for tigecycline was carried out in 144 CRE isolates and tigecycline resistance (MIC >2 μg/ml) was seen in 12 (8.3%) isolates (eight K.pneumoniae and four E. coli). Eight other isolates were found to have MIC of 2 μg/ml and thus the overall prevalence of isolates with decreased susceptibility was 20 (13.9%).

CONCLUSION

A high prevalence of carbapenem resistance coupled with high tigecycline MICs in clinical isolates of E.coli and K. pneumoniae highlights the judicious use of a combination of antimicrobials. Routine in vitro sensitivity testing to evaluate the clinical utility of tigecycline against such resistant Enterobacteriaceae is warranted.

Molecular epidemiology of carbapenem resistant gram-negative bacilli from infected pediatric population in tertiary - care hospitals in Medellín, Colombia: an increasing problem

BACKGROUND

Gram-negative bacilli are a cause of serious infections in the pediatric population. Carbapenem are the treatment of choice for infections caused by multidrug-resistant Gram-negative bacilli, but the emergence of carbapenem resistance has substantially reduced access to effective antimicrobial regimens. Children are a population vulnerable to bacterial infections and the emergence of resistance can worsen prognosis. The aim of this study is to describe the clinical and molecular characteristics of infections caused by carbapenem-resistant Gram-negative bacilli in pediatric patients from five tertiary-care hospitals in Medellín, Colombia.

METHODS

A cross-sectional study was conducted in five tertiary-care hospitals from June 2012 to June 2014. All pediatric patients infected by carbapenem-resistant Gram-negative bacilli were included. Clinical information for each patient was obtained from medical records. Molecular analyses included PCR for detection of bla VIM, bla IMP bla NDM, bla OXA-48 and bla KPC genes and PFGE and MLST for molecular typing.

RESULTS

A total of 59 patients were enrolled, most of them less than 1 year old (40.7 % n = 24), with a previous history of antibiotic use (94.9 %; n = 56) and healthcare-associated infections - predominately urinary tract infections (31.0 %; n = 18). Klebsiella pneumoniae was the most frequent bacteria (47.4 %), followed by Enterobacter cloacae (40.7 %) and Pseudomonas aeruginosa (11.9 %). For K. pneumoniae, KPC was the predominant resistance mechanism (85.7 %; n = 24) and ST14 was the most common clone (39.3 % n = 11), which included strains closely related by PFGE. In contrast, E. cloacae and P. aeruginosa were prevailing non-carbapenemase-producing isolates (only KPC and VIM were detected in 1 and 3 isolates, respectively) and high genetic diversity according to PFGE and MLST was found in the majority of the cases.

CONCLUSIONS

In recent years, increasing carbapenem-resistant bacilli in children has become in a matter of great concern. It is important to conduct systemic surveillance and take measures to prevent dissemination of multidrug-resistant bacteria.

Prevalence of Class D Carbapenemases among Extended-Spectrum β-Lactamases Producing Escherichia coli Isolates from Educational Hospitals in Shahrekord

INTRODUCTION

Extended-spectrum β-lactamases (ESBLs) are a set of plasmid-borne, various and quickly evolving enzymes that are a main therapeutic issue now-a-days for inpatient and outpatient treatment.

AIM

The aim of this study was to determine multi-drug resistance (MDR) and ESBLs producing E. coli strains, prevalence of class D Carbapenemases among ESBLs producing Escherichia coli isolates from educational hospitals in Shahrekord, Iran.

MATERIALS AND METHODS

Uropathogenic Escherichia coli strains were isolated from patients with Urinary Tract Infections (UTIs). The agar disc diffusion test was used to characterize the antimicrobial sensitivity of the E. coli isolates. The ESBL positive strains were identified by phenotypic double-disk synergy test, by third-generation cephalosporin in combination with or without clavulanic acid. Multiplex PCR was carried out for detection of the three families of OXA-type carbapenamases including OXA-23, OXA-24, and OXA-48 in E. coli strains.

RESULTS

All bacterial isolates were susceptible to meropenem. Ninety isolates produced ESBL, 55 E. coli isolates from inpatients, and 35 isolates from outpatients, with a significant association (p< 0.05). The prevalence of OXA-23, OXA-24, and OXA-48 in the ESBLs producing isolates was respectively 21%, 18%, and 11% for inpatients, and 10%, 8%, and 6% for outpatients.

CONCLUSION

ESBL-producing E. coli isolates are also a major threat in the clinical setting. The findings of this study indicated the high occurrence of ESBLs and multiple antibiotic resistance in E. coli isolates.

Characteristics and management of Enterobacteriaceae harboring IMP-4 or IMP-8 carbapenemase in a tertiary hospital

BACKGROUND

The emergence of Enterobacteriaceae harboring IMP-4 or IMP-8 carbapenemases is rare. We report an occurrence of Enterobacteriaceae harboring IMP-4 or IMP-8 carbapenemases in a Chinese tertiary care hospital from November 2010 to December 2012.

METHODS

The clinical characteristics of 30 patients were described. The genetic relationship of isolates was determined by pulsed-field gel electrophoresis (PFGE). Carbapenemases were detected by modified Hodge test (MHT) and polymerase chain reactions (PCRs). Amplicons were sequenced and blasted to determine the genotype.

RESULTS

Most infected patients were from intensive care unit and had complex and serious underlying illnesses requiring mechanical ventilation. PFGE revealed that Klebsiella pneumoniae showed two major PFGE types. Two Klebsiella oxytoca had an indistinguishable PFGE pattern, while four Enterobacter cloacae were different strains. The sequencing studies showed Enterobacteriaceae harboring IMP-4 or IMP-8 carbapenemase in the 23 infected patients. The majority of patients had infections with the carbapenemase-producing Enterobacteriaceae (CPE) strain, most were successfully treated with a range of antibiotics and discharged.

CONCLUSION

It is important to maintain a high index of suspicion to screen for carbapenemase-producing Enterobacteriaceae strains. Rapid identification of these strains and implementation of stringent procedures are the key to prevent major outbreaks in a hospital setting.

Tigecycline Treatment for Carbapenem-Resistant Enterobacteriaceae Infections: A Systematic Review and Meta-Analysis

Carbapenem-resistant Enterobacteriaceae (CRE) infections are prevalent worldwide; they have few effective treatments and this jeopardizes public health. Clinicians often use tigecycline to combat CRE, but its clinical efficacy remains controversial. Therefore, to compare the efficacy and safety of tigecycline in treating CRE infections compared with that of other antimicrobial agents, and to evaluate whether combination therapy and high-dose regimens are beneficial, we performed a systematic review and meta-analysis. PubMed and Embase were searched for controlled trials or cohort studies reporting the efficacy and/or safety of tigecycline-based regimens to treat CRE infections. Statistical analyses were performed using the Comprehensive Meta-Analysis V2.2. All meta-analyses were performed based on fixed- or random-effects model, and the I method was used to assess heterogeneity. Twenty-one controlled studies and 5 single-arm studies were included in this systematic review. With regard to the controlled studies, the tigecycline groups did not differ significantly from the control groups in terms of overall mortality (Odds ratio (OR) = 0.96 [95% confidence interval (CI) = 0.75-1.22; P = 0.73]), clinical response rate (OR = 0.58 [95% CI = 0.31-1.09; P = 0.09]), or microbiological response rate (OR = 0.46 [95% CI = 0.15-1.44; P = 0.18]). Subgroup analyses showed that 30-day mortality was significantly lower in patients who received tigecycline combination therapy than in those who received monotherapy (OR = 1.83 [95% CI = 1.07-3.12; P = 0.03]) and other antibiotic regimens (OR = 0.59 [95% CI = 0.39-0.88; P = 0.01]), respectively. In addition, high-dose tigecycline regimens differed significantly from standard dose schedules in terms of ICU mortality (OR = 12.48 [95% CI = 2.06-75.43; P = 0.006]). The results of the 5 single-arm studies corroborated the findings of the controlled studies. Our results indicated that the efficacy of tigecycline in treating CRE infections is similar to that of other antibiotics. Tigecycline combination therapy and high-dose regimens may be more effective than monotherapy and standard-dose regimens, respectively. Nonetheless, considering that the current available evidence is limited, well-designed randomized controlled trials are urgently needed to clarify the comparative efficacy of tigecycline in treating CRE infections.

Emergence of Carbapenemase Producing Klebsiella Pneumonia and Spread of KPC-2 and KPC-17 in Taiwan: A Nationwide Study from 2011 to 2013

The emergence of carbapenemase-producing Klebsiella pneumoniae (CPKP) has become a great concern worldwide. In this study, 994 non-duplicate, carbapenem non-susceptible Klebsiella pneumonia isolates were collected in Taiwan from 2011 to 2013 for detection of the carbapenemase genes, assessment of antimicrobial susceptibility and molecular epidemiology studies. Of these 994 isolates, 183 (18.4%) had carbapenemase genes: 157 (15.8%) KPC (145 KPC-2 and 12 KPC-17), 16 (1.6%) IMP-8, 9 (0.9%) VIM-1, and 1 (0.1%) NDM-1. KPC had the highest prevalence rate among the carbapenemases and represented a major epidemic clone circulating in Taiwan. The ST512 and ST258 KPC-2 KPs were first identified in Taiwan and were grouped into a small cluster in the PFGE profile. In addition, the genetic structure encompassing the bla_KPC gene of the ST512 and ST258 isolates showed a different pattern from that of other KPC isolates. ST11 may be a major sequence type circulating in Taiwan, although a specific minor clone has begun to be observed. This is the first report of ST258 and ST512 KPC-2 KP isolates in Taiwan, whether ST258 and ST512 will become the next endemic problems in Taiwan should be closely monitored.

Quantification and comparison of virulence and characteristics of different variants of carbapenemase-producing Klebsiella pneumoniae clinical isolates from Taiwan and the United States

BACKGROUND/PURPOSE

The emergence of Klebsiella pneumoniae carbapenemase (KPC)-producing strains is a challenge for clinicians. The characteristics and virulence of variants of KPC-producing K. pneumoniae isolates were evaluated.

METHODS

Five clinical isolates-three KPC subtypes from Taiwan (KPC2-TW, KPC3-TW, and KPC17-TW) and two clinical strains from the United States (US; KPC2-US, KPC3-US)-were included. Virulent traits and capsular serotypes were analyzed by Polymerase Chain Reaction (PCR). Serum killing, neutrophil phagocytosis, and mice lethargy studies were performed to evaluate virulence.

RESULTS

Multilocus sequence typing (MLST) demonstrated that KPC2-TW and KPC17-TW belonged to sequence type (ST)11, and KPC2-US, KPC3-US, and KPC3-TW to ST258. KPC3-TW expressed capsular serotype K1, whereas the others were non-K1/K2/K5 isolates. MLST analysis indicated that ST11 strains were serum resistant, whereas ST258 isolates were serum sensitive. ST11 isolates exhibited significantly higher 15-minute phagocytic rates than ST258 isolates (70.28 ± 16.68% vs. 34.88 ± 10.52%, p < 0.001). The capsular serotype K1 strain was more resistant to neutrophil phagocytosis than non-K1/K2/K5 isolates (27.1 ± 10.23% vs. 54.46 ± 20.94%, p = 0.050). All KPC-producing strain variants from Taiwan and the US demonstrated less virulence in a mouse lethality study, where the LD50 ranged from approximately 10(6) colony-forming units (CFU) to >10(7) CFU. Immunological responses were not significantly correlated with KPC subtype; however, responses were associated with MLST and capsular serotype.

CONCLUSION

Production of KPC itself was not associated with increased virulence despite different variants of KPC. The ST11 KPC-producing strain was resistant to serum killing, whereas capsular ss K1 was associated with resistance to neutrophil phagocytosis.

Identification of DHA-23, a novel plasmid-mediated and inducible AmpC beta-lactamase from Enterobacteriaceae in Northern Taiwan

Objectives: AmpC β-lactamases are classified as Amber Class C and Bush Group 1. AmpC β-lactamases can hydrolyze broad and extended-spectrum cephalosporins, and are not inhibited by β-lactamase inhibitors such as clavulanic acid. This study was conducted to identify DHA-23, a novel plasmid-mediated and inducible AmpC β-lactamase obtained from Enterobacteriaceae.

Methods: A total of 210 carbapenem-resistant Enterobacteriaceae isolates were collected from a medical center (comprising two branches) in Northern Taiwan during 2009–2012. AmpC β-lactamase genes were analyzed through a polymerase chain reaction using plasmid DNA templates and gene sequencing. The genetic relationships of the isolates were typed using pulsed-field gel electrophoresis following the digestion of intact genomic DNA by using XbaI.

Results: Three enterobacterial isolates (one Escherichia coli and two Klebsiella pneumoniae) were obtained from three hospitalized patients. All three isolates were resistant or intermediately susceptible to all β-lactams, and exhibited reduced susceptibility to carbapenems. These three isolates expressed a novel AmpC β-lactamase, designated DHA-23, approved by the curators of the Lahey website. DHA-23 differs from DHA-1 and DHA-6 by one amino acid substitution (Ser245Ala), exhibiting three amino acid changes compared with DHA-7 and DHA-Morganella morganii; three amino acid changes compared with DHA-3; four amino acid changes compared with DHA-5; and eight amino acid changes compared with DHA-2 (>97% identity). This AmpC β-lactamase is inducible using a system involving ampR.

Conclusion: This is the first report to address DHA-23, a novel AmpC β-lactamase. DHA-type β-lactamases are continuous threat in Taiwan.

Efficacy of polymyxins in the treatment of carbapenem-resistant Enterobacteriaceae infections: a systematic review and meta-analysis

In recent years, carbapenem-resistant Enterobacteriaceae has become endemic in many countries. Because of limited treatment options, the abandoned "old antibiotics", polymyxins, have been reintroduced to the clinic. To evaluate the clinical efficacy of polymyxins in the treatment of infections caused by carbapenem-resistant Enterobacteriaceae, we systemically searched the PubMed, Embase, and Cochrane Library databases and analyzed the available evidence. The Preferred Reporting Items for Systematic reviews and Meta-Analysis statement were followed, and the I(2) method was used for heterogeneity. Nineteen controlled and six single-arm cohort studies comprising 1086 patients met the inclusion criteria. For controlled studies, no significant difference was noted for overall mortality (OR, 0.79; 95% CI, 0.58-1.08; p=0.15), clinical response rate (OR, 1.24; 95% CI, 0.61-2.54; p=0.55), or microbiological response rate (OR, 0.59; 95% CI, 0.26-1.36; p=0.22) between polymyxin-treated groups and the control groups. Subgroup analyses showed that 28-day or 30-day mortality was lower in patients who received polymyxin combination therapy than in those who received monotherapy (OR, 0.36; 95% CI, 0.19-0.68; p<0.01) and the control groups (OR, 0.49; 95% CI, 0.31-0.75; p<0.01). The results of the six single-arm studies were in accordance with the findings of controlled studies. One controlled and two single-arm studies that evaluated the occurrence of nephrotoxicity reported a pooled incidence rate of 19.2%. Our results suggest that polymyxins may be as efficacious as other antimicrobial therapies for the treatment of carbapenem-resistant Enterobacteriaceae infection. Compared to polymyxin monotherapy, combination regimens may achieve lower 28-day or 30-day mortality. Future large-volume, well-designed randomized control trials are required to determine the role of polymyxins in treating carbapenem-resistant Enterobacteriaceae infections.

Phenotypic and molecular characteristics of carbapenem-resistant Enterobacteriaceae in a health care system in Los Angeles, California, from 2011 to 2013

Carbapenem-resistant Enterobacteriaceae (CRE) are a concern for health care in the United States but remain relatively uncommon in California. We describe the phenotype, clonality, and carbapenemase-encoding genes present in CRE isolated from patients at a Californian tertiary health care system. CRE for this study were identified by evaluating the antibiograms of Enterobacteriaceae isolated in the UCLA Health System from 2011 to 2013 for isolates that were not susceptible to meropenem and/or imipenem. The identification of these isolates was subsequently confirmed by matrix-associated laser desorption ionization-time of flight, and broth microdilution tests were repeated to confirm the CRE phenotype. Real-time PCR for bla(KPC), bla(SME), bla(IMP), bla(NDM-1), bla(VIM), and bla(OXA-48) was performed. Clonality was assessed by repetitive sequence-based PCR (repPCR) and multilocus sequence typing (MLST). Of 15,839 nonduplicate clinical Enterobacteriaceae isolates, 115 (0.73%) met the study definition for CRE. This number increased from 0.5% (44/8165) in the first half of the study to 0.9% (71/7674) in the second (P = 0.004). The most common CRE species were Klebsiella pneumoniae, Enterobacter aerogenes, and Escherichia coli. A carbapenemase-encoding gene was found in 81.7% (94/115) of CRE and included bla(KPC) (78.3%), bla(NDM-1) (0.9%), and bla(SME) (2.6%). The majority of bla(KPC) genes were in K. pneumoniae isolates, which fell into 14 clonal groups on typing. bla(KPC) was identified in more than one species of CRE cultured from the same patient in four cases. Three bla(SME)-carrying Serratia marcescens isolates and one bla(NDM-1) carrying Providencia rettgeri isolate were detected. CRE are increasing in California, and carbapenemases, particularly KPC, are a common mechanism for carbapenem resistance in this region.

Antibiotic treatment of infections due to carbapenem-resistant Enterobacteriaceae: systematic evaluation of the available evidence

We sought to evaluate the effectiveness of the antibiotic treatment administered for infections caused by carbapenemase-producing Enterobacteriaceae. The PubMed and Scopus databases were systematically searched. Articles reporting the clinical outcomes of patients infected with carbapenemase-producing Enterobacteriaceae according to the antibiotic treatment administered were eligible. Twenty nonrandomized studies comprising 692 patients who received definitive treatment were included. Almost all studies reported on Klebsiella spp. In 8 studies, the majority of infections were bacteremia, while pneumonia and urinary tract infections were the most common infections in 12 studies. In 10 studies, the majority of patients were critically ill. There are methodological issues, including clinical heterogeneity, that preclude the synthesis of the available evidence using statistical analyses, including meta-analysis. From the descriptive point of view, among patients who received combination treatment, mortality was up to 50% for the tigecycline-gentamicin combination, up to 64% for tigecycline-colistin, and up to 67% for carbapenem-colistin. Among the monotherapy-treated patients, mortality was up to 57% for colistin and up to 80% for tigecycline. Certain regimens were administered to a small number of patients in certain studies. Three studies reporting on 194 critically ill patients with bacteremia showed individually significantly lower mortality in the combination arm than in the monotherapy arm. In the other studies, no significant difference in mortality was recorded between the compared groups. Combination antibiotic treatment may be considered the optimal option for severely ill patients with severe infections. However, well-designed randomized studies of specific patient populations are needed to further clarify this issue.