Carbapenem-resistant Enterobacteriaceae: What we know and what we need to know

Updates on the Status of Carbapenem-Resistant Enterobacterales in Lebanon

Carbapenem-resistant Enterobacterales (CRE) pathogens have been increasingly isolated and reported in Lebanon. Several studies have been published over the last two decades about the CRE situation in the country. However, compared to the worldwide data, those studies are scarce and mostly restricted to single center studies. In this review, we aim to present a comprehensive and reliable report illustrating the current situation regarding CRE in Lebanon. Variable studies have shown an increasing pattern of carbapenem resistance in Enterobacterales since the first reports of CRE isolates in 2007 and 2008. Escherichia coli and Klebsiella pneumoniae were the most detected ones. The OXA-48 class D carbapenemases were the most prevalent carbapenemases among CRE isolates. Moreover, the emergence of other carbapenemases like the NDM class B carbapenemase has been noticed. Strict infection control measures in hospitals, including the identification of CRE carriers, are needed in Lebanese hospitals since carriage is a potential risk for the spread of CRE in healthcare settings. The dissemination of CRE in the community is noticed and attributed to multiple causes, such as the refugee crisis, water contamination, and antimicrobial misuse. In conclusion, strict infection control measures in healthcare settings, in addition to accurate antimicrobial stewardship program implementation, are urgently needed.

Active Screening of Intestinal Colonization of Carbapenem-Resistant Enterobacteriaceae for Subsequent Bloodstream Infection in Allogeneic Hematopoietic Stem Cell Transplantation

Purpose

To investigate the prevalence, risk factors of intestinal carbapenem-resistant Enterobacteriaceae (CRE) colonization and bloodstream infection (BSI) caused by CRE in allogeneic hematopoietic stem cell transplantation (allo-HSCT) recipients.

Methods

We analyzed the clinical data of 185 patients with hematological malignancies who underwent allo-HSCT from May 2019 to December 2021. All patients received regular CRE monitoring by rectal swab during allo-HSCT, and some CRE strains were further identified for carbapenemase phenotypes. The rates, distribution and risk factors of CRE colonization, CRE-induced BSI were analyzed.

Results

CRE was detected in 44 of 185 recipients, with colonization rate of 23.8%. A total of 46 strains of CRE were isolated, including 22 Escherichia coli, 17 Klebsiella pneumoniae, three Klebsiella oxytoca, two Enterobacter hormaechei, and two other Enterobacteriaceae. Among the 19 strains identified with carbapenemase phenotypes, eight strains of E. coli produced metal β-lactamase, five K. pneumoniae produced serine carbapenemase, two K. pneumoniae produced metal β-lactamase, two K. oxytoca produced metal β-lactamase, a Citrobacter malonic acid-free produced metal β-lactamase and a Citrobacter freundii produced metal β-lactamase. In 10 patients developed with CRE-related BSI, the types and combined drug sensitivity of strains detected by rectal swab were highly consistent with blood culture. Multivariate analysis revealed that pulmonary infection, perianal infection and carbapenem application in the 3 months pre-transplant were independent risk factors for rectal CRE colonization, while rectal colonization with carbapenem-resistant K. pneumoniae (CR-KP) was an independent risk factor for CRE-induced BSI. The mortality rate within 30 days of CRE-related BSI was 50.0%, and patients receiving multi-drug therapy within 24 hours showed slightly lower mortality than that in the single-drug treatment group.

Conclusion

Allo-HSCT patients with CRE-induced BSI have poor prognosis, and CR-KP rectal colonization is an independent risk factor for CRE-related BSI. Rectal swab screening during allo-HSCT could provide early warning for later CRE-induced BSI.

Assessing Colistin Resistance by Phenotypic and Molecular Methods in Carbapenem-resistant Enterobacterales in a Tertiary Care Hospital in Pakistan

Introduction

Members of Enterobacterales are very common pathogens, which continue to show resistance to many antibiotics. Carbapenem performed well for some time. Colistin was the final hope for the carbapenem-resistant Enterobacterales, but resistance against it has virtually tied the clinician's hands, especially when it comes to treating critically ill patients.

Purpose

Detection of colistin resistance by the agar method as well as by the polymerase chain reaction (mobilized colistin resistance-1 gene) in carbapenem-resistant Enterobacterales.

Materials and Methods

A cross-sectional study from Dec 2019 to Dec 2020 was conducted at the Department of Microbiology, Army Medical College, National University of Medical Sciences Rawalpindi Pakistan. Antimicrobial susceptibility of Enterobacterales was determined according to the Kirby-Bauer disc diffusion method except for colistin. Colistin agar was used, in concentrations of 2 µg/mL and 4 µg/mL. Results were interpreted according to Clinical and Laboratory Standards Institute guidelines 2020. Mobilized colistin-resistant-1 gene in the carbapenem resistant Enterobacterales was detected by performing real-time polymerase chain reaction assay.

Results

Among the 172 carbapenem-resistant Enterobacterales 18 isolates were resistant using the colistin agar test. Whereas by molecular method colistin resistance was detected among 10 isolates that carried mobilized colistin resistance 1 gene, making the frequency of the MCR-1 gene 5.81%. Seventy percent of isolates were from paired blood samples. Eight patients, from whom the colistin resistant gene was isolated expired.

Conclusion

Colistin resistance is a very serious issue and should not be missed in a clinical microbiology laboratory. The phenotypic agar test method is an excellent option for routine use, as it combines ease of performance with affordable cost. However, molecular methods are essential for the detection of mobilized colistin resistance gene (1-9) for epidemiological purposes.

Multidrug-Resistant Bacteria: Their Mechanism of Action and Prophylaxis

In the present scenario, resistance to antibiotics is one of the crucial issues related to public health. Earlier, such resistance to antibiotics was limited to nosocomial infections, but it has now become a common phenomenon. Several factors, like extensive development, overexploitation of antibiotics, excessive application of broad-spectrum drugs, and a shortage of target-oriented antimicrobial drugs, could be attributed to this condition. Nowadays, there is a rise in the occurrence of these drug-resistant pathogens due to the availability of a small number of effective antimicrobial agents. It has been estimated that if new novel drugs are not discovered or formulated, there would be no effective antibiotic available to treat these deadly resistant pathogens by 2050. For this reason, we have to look for the formulation of some new novel drugs or other options or substitutes to treat such multidrug-resistant microorganisms (MDR). The current review focuses on the evolution of the most common multidrug-resistant bacteria and discusses how these bacteria escape the effects of targeted antibiotics and become multidrug resistant. In addition, we also discuss some alternative mechanisms to prevent their infection as well.

Resistance to beta-lactams in Gram-negative bacilli: relevance and potential therapeutic alternatives

The indiscriminate and massive antibiotic use in the clinical practice and in agriculture or cattle during the past few decades has produced a serious world health problem that entails high morbidity and mortality: the antibiotic multi-drug resistance. In 2017 and 2019, the World Health Organization published a list of urgent threats and priorities in the context of drug resistance, which only included Gram-negative bacteria and specially focused on carbapenem-resistant Acinetobacter baumannii and Pseudomonas aeruginosa, as well as carbapenem and third generation cephalosporin-resistant Enterobacteriaceae. This scenario emphasizes the need of developing and testing new antibiotics from different families, such as new beta-lactams, highlighting cefiderocol and its original mechanism of action; new beta-lactamase inhibitors, with vaborbactam or relebactam among others; new quinolones such as delafloxacin, and also omadacycline or eravacycline, as members of the tetracycline family. The present work reviews the importance and impact of Gram-negative bacterial infections and their resistance mechanisms, and analyzes the current therapeutic paradigm as well as the role of new antibiotics with a promising future in the era of multi and pan-drug resistance.

Parallel Reaction Monitoring Mass Spectrometry for Rapid and Accurate Identification of β-Lactamases Produced by Enterobacteriaceae

The increasing spread of drug-resistant bacterial strains presents great challenges to clinical antibacterial treatment and public health, particularly with regard to β-lactamase-producing Enterobacteriaceae. A rapid and accurate detection method that can expedite precise clinical diagnostics and rational administration of antibiotics is urgently needed. Targeted proteomics, a technique involving selected reaction monitoring or multiple reaction monitoring, has been developed for detecting specific peptides. In the present study, a rapid single-colony-processing procedure combined with an improved parallel reaction monitoring (PRM) workflow based on HRAM Orbitrap MS was developed to detect carbapenemases (Klebsiella pneumoniae carbapenemase, KPC; imipenemase, IMP; Verona integron-encoded metallo-β-lactamase, VIM; New Delhi metallo-β-lactamase, NDM; and oxacillinase, OXA), extended spectrum β-lactamases (TEM and CTX-M), and AmpC (CMY-2) produced by Enterobacteriaceae. Specific peptides were selected and validated, and their coefficients of variation and stability were evaluated. In total, 188 Enterobacteriaceae strains were screened using the workflow. Fourteen out of total 19 peptides have 100% specificity; three peptides have specificity >95% and two peptides have specificity ranged from 74∼85%. On the sensitivity, only nine peptides have 95∼100% sensitivity. The other 10 peptides have sensitivity ranged from 27∼94%. Thus, a screening method based on peptide groups was developed for the first time. Taken together, this study described a rapid extraction and detection workflow for widespread β-lactamases, including KPC, IMP, VIM, NDM, OXA, CMY, CTX-M, and TEM, using single colonies of Enterobacteriaceae strains. PRM-targeted proteomics was proven to be a promising approach for the detection of drug-resistant enzymes.

Genomic Insights Into the Mechanism of Carbapenem Resistance Dissemination in Enterobacterales From a Tertiary Public Heath Setting in South Asia

SUMMARY

10.6% patients were CRE positive. Only 27% patients were prescribed at least 1 antibiotic to which infecting pathogen was susceptible. Burn and ICU admission and antibiotics exposures facilitate CRE acquisition. Escherichia coli ST167 was the dominant CRE clone.

BACKGROUND

Given the high prevalence of multidrug resistance (MDR) across South Asian (SA) hospitals, we documented the epidemiology of carbapenem-resistant Enterobacterales (CRE) infections at Dhaka Medical College Hospital between October 2016 and September 2017.

METHODS

We enrolled patients and collected epidemiology and outcome data. All Enterobacterales were characterized phenotypically and by whole-genome sequencing. Risk assessment for the patients with CRE was performed compared with patients with carbapenem-susceptible Enterobacterales (CSE).

RESULTS

10.6% of all 1831 patients with a clinical specimen collected had CRE. In-hospital 30-day mortality was significantly higher with CRE [50/180 (27.8%)] than CSE [42/312 (13.5%)] (P = .001); however, for bloodstream infections, this was nonsignificant. Of 643 Enterobacterales isolated, 210 were CRE; blaNDM was present in 180 isolates, blaOXA-232 in 26, blaOXA-181 in 24, and blaKPC-2 in 5. Despite this, ceftriaxone was the most commonly prescribed empirical antibiotic and only 27% of patients were prescribed at least 1 antibiotic to which their infecting pathogen was susceptible. Significant risk factors for CRE isolation included burns unit and intensive care unit admission, and prior exposure to levofloxacin, amikacin, clindamycin, and meropenem. Escherichia coli ST167 was the dominant CRE clone. Clustering suggested clonal transmission of Klebsiella pneumoniae ST15 and the MDR hypervirulent clone, ST23. The major trajectories involved in horizontal gene transfer were IncFII and IncX3, IS26, and Tn3.

CONCLUSIONS

This is the largest study from an SA public hospital combining outcome, microbiology, and genomics. The findings indicate the urgent implementation of targeted diagnostics, appropriate antibiotic use, and infection-control interventions in SA public institutions.

Carbapenem-resistant bacteria on hand-held and hands-free electronic devices of healthcare workers and non-healthcare workers in Delhi, India

Background

Monitoring sensitivity profiles of circulating hospital strains is a key activity of a hospital infection control policy. The hospital environment and equipment may be reservoirs for carbapenem-resistant bacteria. Mobile phones have been shown to be a potential source for the transmission of bacteria in the healthcare environment.

Methods

Bacteria were cultured from seven common electronic devices. These included touchpads, chargers, hands-free headphones/microphones, laptops, digital wristwatches and computer mice which were used by healthcare workers and non-healthcare workers including family members and patient attendants. The Gram-negative bacteria were further analysed for phenotypic and genotypic (bla_KPC, bla_NDM-1 genes) carbapenem resistance.

Results

110 Gram-negative bacteria were isolated Mobile phones were found to be the most heavily contaminated devices and hands-free devices the least. 53.6% (n=59/110) Gram-negative bacteria were phenotypically carbapenem-resistant of which 36.37% (n=40) were metallo-β-lactamase positive. 40% (n=44/110) were genotypically resistant and 30% (n=33) were bla_NDM-1 gene positive. 9% (n=10) bacteria had both bla_NDM–1and bla_KPC genes.

Conclusions

Carbapenem-resistant bacteria are widespread in India's hospital environment and present a challenge in healthcare. Electronic devices are a potential vehicle for the transmission of carbapenem-resistant bacteria. The results of the study support that hands-free electronic devices are less likely to be contaminated with carbapenem-resistant bacteria and that promoting the use of hands-free devices may help to reduce the spread of multidrug resistant bacteria in healthcare.

mCIM test as a reliable assay for the detection of CRE in the Gulf region

Introduction. Carbapenem resistant Enterobacterales (CRE) are one of the leading causes of systemic and nosocomial infections and are multidrug-resistant organisms producing different carbapenemases. There are many genotypic and phenotypic methods for detecting the carbapenemases; however, there is a limitation for each. Modified carbapenem inactivation method (mCIM) assay is a recent phenotypic method which has been published by the Clinical and Laboratory Standards Institute.Hypothesis / Gap Statement. mCIM assay could provide a reliable method for the detection of carbapenemases in CRE.Aim. Evaluation of the mCIM assay performance for the detection of carbapenemases in Enterobacterales and the identification of the common carbapenemase genes at Eastern Province of Saudi Arabia and Kingdom of Bahrain.Methodology. A collection of 197 non-duplicate carbapenem resistant Enterobacterales clinical isolates, were evaluated with the mCIM test comparing its performance to multiplex PCR. The minimum inhibitory concentration susceptibility testing was done by the Etest method for imipenem, meropenem, and ertapenem.Results. The sensitivity of the mCIM assay was 94 % (95 % CI, (89.3-97.1)). In Saudi Arabia and Bahrain, OXA-48 was the most prevalent carbapenemase gene followed by NDM. Coexistence of multiple carbapenemase genes is reported in eleven cases.Conclusion. These findings indicate that the mCIM test is a reliable and simple assay for detecting the activity of carbapenemase in Enterobacterales, especially in resource-limited laboratories.

Guía de práctica clínica para la tamización de pacientes con riesgo de colonización por Enterobacterales productores de carbapenemasas y el manejo de infecciones causadas por estas bacterias

Las infecciones por Enterobacterales productores de carbapenemasas (EPC) han aumentado en los últimos años. Colombia se ha convertido en un país endémico para este grupo de microorganismos y las infecciones que causan tienen un impacto importante en términos de morbilidad y mortalidad. La identificación temprana de los portadores de EPC que ingresan como pacientes a las instituciones de salud es necesaria para implementar medidas de aislamiento y control de infecciones adecuadas que limiten la diseminación de este tipo de microorganismos en los hospitales. Además, el tratamiento de estas infecciones es difícil debido a las limitadas alternativas terapéuticas disponibles y la escasez de estudios que demuestren su efectividad en este escenario. Por lo anterior, el objetivo del presente trabajo es desarrollar una guía de práctica clínica (GPC) para la tamización de pacientes con riesgo de colonización por EPC y para el manejo de pacientes con   infecciones, ya sea sospechadas o confirmadas, causadas por este tipo de bacterias, mediante un proceso de adaptación de GPC basado en la metodología ADAPTE. Con este propósito en mente, se hacen recomendaciones informadas en evidencia para realizar la tamización y oportuna identificación de portadores de EPC admitidos en instituciones hospitalarias, así como para el adecuado manejo farmacológico de las infecciones por EPC en este escenario.

[Active screening of intestinal carbapenem-resistant Enterobacteriaceae in high-risk patients admitted to the hematology wards and its effect evaluation]

目的

观察血液科肠道碳青霉烯类耐药的肠杆菌科细菌（CRE）主动筛查患者CRE定植、感染的特征，并评价主动筛查结合加强干预在血液科患者CRE感染预防控制中的效果。

方法

以2017年3月至2019年12月血液内科接受化疗或免疫抑制治疗且预期会出现粒细胞缺乏（粒缺）的患者为研究对象，进行至少3个时间点（治疗前、治疗后粒缺期、粒缺伴发热期）的肠道CRE筛查，以2016年12月至2017年2月血液内科未开展肠道CRE主动筛查的、接受化疗或免疫抑制治疗的115例患者为历史对照组，两组患者均进行CRE感染实时监测，CRE筛查阳性者均采取接触隔离措施，CRE筛查阳性者出现发热或者感染症状时启动针对CRE联合抗生素治疗。

结果

主动筛查患者CRE定植率为16.46%（66/401）；病种分布上，以急性白血病定植率最高，为23.03%（26/113）。66例筛查阳性患者中，其中第1次筛查阳性患者为27例，占40.9%（27/66），第2次筛查阳性患者为15例，占22.7%（15/66），第3次及以后筛查阳性患者为24例，占36.4%（24/66）。CRE定植病原菌中耐碳青霉烯类肺炎克雷伯菌（CRKP）最多，占54.55%（36/66）。主动筛查患者CRE感染率（2.49%）及死亡率（50.00%）低于历史对照组的11.30%及69.23%；干预期间10例CRE血流感染患者病原菌种类与前期主动筛查病原菌完全相同，符合率为100.0%。

结论

血液科病房急性白血病患者CRE定植率最高，CRKP是CRE定植、感染的主要病原菌，提高筛查频率可以显著提高筛查阳性率，采取主动筛查并及早干预能有效降低血液科患者CRE发生率及死亡率，CRE筛查阳性病原菌与后续CRE感染病原菌符合率高。恶性血液病患者肠道CRE筛查可以对后期CRE血流感染起到预警以及优化抗菌药物使用的作用。

Cost-effectiveness of antimicrobial treatment for inpatients with carbapenem-resistant Klebsiella pneumoniae infection: a systematic review of economic evidence

OBJECTIVES

The objective of this review was to evaluate the cost-effectiveness of antimicrobial therapy for patients with carbapenem-resistant Klebsiella pneumoniae infection.

INTRODUCTION

Among the main multi-resistant microorganisms, carbapenem-resistant K. pneumoniae is responsible for the mortality of 40% of patients following 30 days of infection. Treatment for carbapenem-resistant K. pneumoniae infection entails the use of high-cost antimicrobials. Inappropriate use of antimicrobials can increase the cost of treatment fourfold. This review aimed to evaluate the cost-effectiveness of antimicrobial therapy treatment for patients with carbapenem-resistant K. pneumoniae infection to better inform decision making in hospital services.

INCLUSION CRITERIA

The review included studies on participants 18 years or over with carbapenem-resistant K. pneumoniae infection who had undergone antimicrobial therapy in hospital and acute care services. Studies that compared the cost-effectiveness of different antimicrobial therapy for carbapenem-resistant K. pneumoniae infection were included. Outcome measures were cost per unit of effect expressed in clinical outcome units; this included cost per avoided death, cost per prevention of sepsis and cost per duration of stay. Economic studies with a cost-effectiveness design were considered, as well as modeling studies.

METHODS

A three-step search strategy was utilized to locate studies published in English, Spanish or Portuguese, with no date restrictions. Two independent reviewers screened titles and abstracts and the full texts of potentially relevant studies for eligibility. Methodological quality was assessed by two independent reviewers using the JBI critical appraisal checklist for economic evaluations. Data were extracted from included studies using the standardized JBI data extraction tool. Data were synthesized using narrative, tables and the JBI Dominance Ranking Matrix.

RESULTS

This review identified eight studies that evaluated the cost-effectiveness of different treatments for carbapenem-resistant K. pneumoniae infection. The results of this study demonstrated that there was no gold standard treatment for carbapenem-resistant K. pneumoniae infection, hence treatment was generally directed by colonization pressure and resistance profiles. Furthermore, due to the moderate quality and limited number of studies, there was high uncertainty of the values of the cost-effectiveness ratio.

CONCLUSIONS

Ofloxacin appears to be the most cost-effective treatment; however, conclusions are limited due to the small number and low quality of studies.

Rising Threat of OXA-48 and other Carbapenemase Encoding Genes among Carbapenem Resistant Enterobacteriaceae in India

Members of Enterobacteriaceae family are responsible for both community and hospital acquired infections. Because of development of antimicrobial resistance carbapenem has remained as last resort of drug for treatment of infections caused by these bacteria.Mechanism for development of this resistance in carbapenem resistant Enterobacteriaceae (CRE) may due to production of carbapenemases, efflux mechanism or loss of outer membrane porins.The most common carbapenemase enzymes are Class A – KPC, Class B – NDM, VIM and IMP and Class D oxacillinase(OXA-48 like enzymes).In India, most prevalent carbapenemase encoding gene is NDM-1but there is rising threat of OXA-48 prevalence. Unlike the phenotypic methods, the genotypic methods are useful to discriminate the type of carbapenemase enzyme, specifically for OXA-48 like enzymes. Total 170 CRE isolates were subjected for multiplex PCR study for their molecular characterization. Of the 170 CRE isolates,68.2 % (n=116) were positive for NDM-1 gene while 44.1 % (n= 75) of the isolates showed presence of OXA-48 gene. VIM (2.3%), KPC (1.7 %) were responsible for carbapenemase production while none of the isolates showed presence of IMP gene. NDM-1 and OXA-48 coexisted in 21.2 % (n=36) of the total isolates. OXA-48 causes weak hydrolysis of carbapenem because of which it is under reported with routine diagnostic methods. Early detection of OXA-48 and other carbapenemase encoding genes, helps for contact precautions and effective therapy which prevents further escalation and horizontal spread of CRE.

Resistance of Gram-Negative Bacteria to Current Antibacterial Agents and Approaches to Resolve It

Antimicrobial resistance represents an enormous global health crisis and one of the most serious threats humans face today. Some bacterial strains have acquired resistance to nearly all antibiotics. Therefore, new antibacterial agents are crucially needed to overcome resistant bacteria. In 2017, the World Health Organization (WHO) has published a list of antibiotic-resistant priority pathogens, pathogens which present a great threat to humans and to which new antibiotics are urgently needed the list is categorized according to the urgency of need for new antibiotics as critical, high, and medium priority, in order to guide and promote research and development of new antibiotics. The majority of the WHO list is Gram-negative bacterial pathogens. Due to their distinctive structure, Gram-negative bacteria are more resistant than Gram-positive bacteria, and cause significant morbidity and mortality worldwide. Several strategies have been reported to fight and control resistant Gram-negative bacteria, like the development of antimicrobial auxiliary agents, structural modification of existing antibiotics, and research into and the study of chemical structures with new mechanisms of action and novel targets that resistant bacteria are sensitive to. Research efforts have been made to meet the urgent need for new treatments; some have succeeded to yield activity against resistant Gram-negative bacteria by deactivating the mechanism of resistance, like the action of the β-lactamase Inhibitor antibiotic adjuvants. Another promising trend was by referring to nature to develop naturally derived agents with antibacterial activity on novel targets, agents such as bacteriophages, DCAP(2-((3-(3,6-dichloro-9H-carbazol-9-yl)-2-hydroxypropyl)amino)-2(hydroxymethyl)propane1,3-diol, Odilorhabdins (ODLs), peptidic benzimidazoles, quorum sensing (QS) inhibitors, and metal-based antibacterial agents.

Infections due to carbapenemase-producing bacteria, clinical burden, and impact of screening strategies on outcome

OBJECTIVES

To characterize the risk factors, impact of screening, and clinical burden of colonization and/or infection by carbapenemase-producing bacteria (CPB) in hospitalized patients.

METHOD

Retrospective study in a tertiary care hospital between 2008 and 2016.

RESULTS

Among 88 included patients, 41% were colonized, 59% developed an infection, and 69% of all cases were hospital-acquired. Risk factors for CPB contamination included recent invasive medical device (94% of patients), antibiotic therapy (82%), travel abroad (17%), and hospitalization (>50%) with 80% of all patients with underlying chronic condition. Intestinal carriage represented 89% of all colonization cases and 50% of infections were located in the urinary tract. The recent use of mechanical ventilation devices was significantly more observed in infected patients than colonized patients. The most frequent CPB was Klebsiella pneumoniae and the most frequent carbapenemase was OXA-48. Overall mortality rate was 19%. Prevalence of CPB detection in intensive care units (ICU) based on systematical rectal screen swab upon admission remained <0.5%. The infected/colonized ratio (CPB colonization cases evolving into an infection) was 23%. The time between CPB infection diagnosis and start of appropriate antimicrobial therapy increased from 1 day in previously screened patients with positive CPB to 4 days in patients with previous negative or absent screening.

CONCLUSION

Our results emphasize the importance of CPB screening in all ICU patients and in at-risk patients hospitalized in other units, to allow earlier adequate antibiotic therapy in case of infection which occurred in 23% of the colonized patients.

Carbapenem resistant organisms: A 9-year surveillance and trends at Saint George University Medical Center

INTRODUCTION

Carbapenem resistant organisms (CRO) constitute a large group of bacteria with different mechanisms of resistance and recently increasing global incidence. This rise has ambiguous dynamics and essential local epidemiologic data is lacking.

MATERIALS AND METHODS

In this retrospective study at the 400-bed Saint George Hospital (SGH) in Beirut, Lebanon, we retrieved electronic laboratory records of all intrinsic and acquired CRO isolates from January 1, 2010 until June 30, 2018. Isolation density was calculated as: number of isolates/1000PD. Analysis carried out using WHOnet with a trend time series analysis.

RESULTS

During the study period, a total of 2150 non-duplicate CRO were isolated. While Acinetobacter baumanii (AB), Pseudomonas aeruginosa (CRPa), and Stenotrophomonas maltophilia (Sm) constituted 85% of total CRO in the study period, the carbapenem resistant enterobacteriaceae (CRE) rose from few sporadic cases before 2016 to a solid 32% of total CRO in 2018. Our most concrete trends were as follows. The rate of AB bacteremia was at an average of 0.114/1000 PD from 2011 to 2014. In 2015, a sudden doubling of AB bacteremia to 0.23/1000 PD. In 2017, there was a significant decrease to 0.113/1,000PD (p < 0.0001) to reach 0.097/1000PD in 2018 with a continuously declining trend. The peak of Sm bacteremia was in 2016 at 0.121/1000PD after which it significantly decreased by 21% in 2017 to disappear in 2018 (p < 0.0001). There were no significant trends observed in the isolation density of the CRPa group from 2010 until June 2018. Klebsiella pneumonia (CRKp) bacteremia was isolated first in 2013, then in 2016 and continued to rise (p = 0.028). In 2017, carbapenem resistant KP bacteremia rate doubled to 0.05/1,000PD from 0.024/1000 (p = 0.0139).

CONCLUSION

In conclusion, this 9-year study at SGH depicts the major trends and dynamics of local CRO isolation, mainly A. baumanii, P. aeruginosa and CRKp. Further efforts are warranted both locally and internationally for a richer understanding of this trend. Bearing in mind that understanding antimicrobial resistance is a complex, multifaceted process that is only feasible when all its aspects are combined: molecular, phenotypic and clinical.

[Perianal swabs surveillance cultures of Carbapenem-resistant Enterobacteriaceae(CRE) can be hints for CRE bloodstream infection in patients with hematological diseases]

目的

探讨血液病患者肛周皮肤拭子细菌培养检出耐碳青霉烯类肠杆菌（CRE）对CRE血流感染的预警价值，寻找CRE血流感染的危险因素。

方法

对2016年1月至2017年12月进行肛周皮肤拭子细菌培养的血液病患者分离出CRE的耐药率、患者后期CRE血流感染发生情况及危险因素进行回顾性分析。

结果

2 914例血液病患者进行了肛周皮肤拭子细菌培养，74例检出CRE，其中后期发生CRE血流感染者13例（17.6%）。共分离出CRE 87株（相同患者相同部位去重），包括肺炎克雷伯菌31株、大肠埃希菌43株、阴沟肠杆菌8株、其他肠杆菌科细菌6株。分离出CRE菌株对哌拉西林/他唑巴坦、亚胺培南、美罗培南、阿米卡星、左氧氟沙星、替加环素的耐药率分别为91.9%、74.4%、98.8%、17.6%、74.4%和8.0%。13例发生CRE血流感染患者肛周皮肤拭子与血液中分离株对碳青霉烯类、氨基糖苷类、喹诺酮类及替加环素耐药程度一致率较高。粒细胞缺乏（粒缺）、存在消化道症状、肛周感染持续时间为肛周皮肤CRE阳性患者发生CRE血流感染的独立危险因素（OR值分别为1.10、1.13和1.23，P值分别为0.029、0.005、0.016）。

结论

对血液病患者进行肛周皮肤拭子细菌培养可为后期CRE血流感染提供预警，并可为其提供抗菌药物选择参考；粒缺、伴消化道症状以及肛周感染持续时间长可作为CRE血流感染患者早期识别因素。

Molecular characterization of carbapenemases of clinical Acinetobacter baumannii-calcoaceticus complex isolates from a University Hospital in Tunisia

The aim of this study was to identify the carbapenemases from clinical carbapenem-resistant Acinetobacter baumannii-calcoaceticus complex (CRABC) isolates and to assess their potential dissemination by conjugation and natural transformation. CRABC (n = 101) were collected consecutively from inpatients of the University Hospital of Monastir, Tunisia, from 2013 to 2016. Antimicrobial susceptibility was determined by the disk diffusion method and E-test. Carbapenemase-encoding genes were screened by PCR. Genotyping was performed by Pasteur MLST scheme. Isolates were resistant to all beta-lactams, fluoroquinolones and aminoglycosides while 80 and 90% were susceptible to tigecycline and colistin, respectively. Resistance and intermediate resistance to imipenem were 87 and 13%, respectively. The genes bla_OXA-24-like, bla_OXA-58-like, bla_OXA-143-like, bla_OXA-48-like, bla_VIM, bla_IMP, and bla_KPC were not found. The bla_OXA-51-like and bla_OXA-23-like genes were present in 100 and 82.17% isolates, respectively. One isolate (< 1%) carried bla_NDM-1 and bla_OXA-51-like and belonged to Sequence Type 85 (ST85). Absence of transconjugants suggests a chromosomal location of NDM-1 determinant. The bla_NDM-1 gene was inserted in a truncated form of Tn125, which may explain the absence of bla_NDM-1 carrier-transformants. To our knowledge, this is the first report of the finding of NDM-positive A. baumannii in Tunisian territory. The study shows that despite the low prevalence and potential spread of NDM-1 enzyme among CRABC, continuous regional antimicrobial resistance surveillance and improved infection control measures are required in Tunisia to prevent further dissemination.