Molecular epidemiology & therapeutic options of carbapenem-resistant Gram-negative bacteria

Antimicrobial Resistance Profiles of Pseudomonas aeruginosa in the Arabian Gulf Region Over a 12-Year Period (2010-2021)

OBJECTIVES

To evaluate literature from a 12-year period (2010-2021) on the antimicrobial resistance profile of Pseudomonas aeruginosa from the Arabian Gulf countries (Bahrain, Kuwait, Oman, Qatar, Saudi Arabia, and the United Arab Emirates).

METHODS

An electronic literature search was conducted for articles on antimicrobial resistance in P. aeruginosa and associated phenotypes, covering the period of 1st January 2010 to 1st December 2021.

RESULTS

Antimicrobial resistance in the Arabian Gulf was highest to meropenem (10.3-45.7%) and lowest to colistin (0.0-0.8%), among the agents tested. Annual data showed that ceftazidime resistance (Kuwait), piperacillin-tazobactam non-susceptibility (Qatar), and aztreonam, imipenem, and meropenem resistance (Saudi Arabia) increased by 12-17%. Multiple mechanisms of carbapenem resistance were identified and multiple clones were detected, including high-risk clones such as ST235. The most common carbapenemases detected were the VIM-type metallo-β-lactamases.

CONCLUSIONS

Among P. aeruginosa in the Arabian Gulf countries, resistance to meropenem was higher than to the other agents tested, and meropenem resistance increased in Saudi Arabia during the study period. Resistance to colistin, a classic antibiotic used to treat Pseudomonas spp. infections, remained low. The VIM-type β-lactamase genes were dominant. We recommend local and regional antimicrobial resistance surveillance programs to detect the emergence of resistance genes and to monitor antimicrobial resistance trends in P. aeruginosa.

Molecular characterization and descriptive analysis of carbapenemase-producing Gram-negative rod infections in Bogota, Colombia

In this study, the genetic differences and clinical impact of the carbapenemase-encoding genes among the community and healthcare-acquired infections were assessed. This retrospective, multicenter cohort study was conducted in Colombia and included patients infected with carbapenem-resistant Gram-negative rods between 2017 and 2021. Carbapenem resistance was identified by Vitek, and carbapenemase-encoding genes were identified by whole-genome sequencing (WGS) to classify the alleles and sequence types (STs). Descriptive statistics were used to determine the association of any pathogen or gene with clinical outcomes. A total of 248 patients were included, of which only 0.8% (2/248) had community-acquired infections. Regarding the identified bacteria, the most prevalent pathogens were Pseudomonas aeruginosa and Klebsiella pneumoniae. In the WGS analysis, 228 isolates passed all the quality criteria and were analyzed. The principal carbapenemase-encoding gene was blaKPC, specifically blaKPC-2 [38.6% (88/228)] and blaKPC-3 [36.4% (83/228)]. These were frequently detected in co-concurrence with blaVIM-2 and blaNDM-1 in healthcare-acquired infections. Notably, the only identified allele among community-acquired infections was blaKPC-3 [50.0% (1/2)]. In reference to the STs, 78 were identified, of which Pseudomonas aeruginosa ST111 was mainly related to blaKPC-3. Klebsiella pneumoniae ST512, ST258, ST14, and ST1082 were exclusively associated with blaKPC-3. Finally, no particular carbapenemase-encoding gene was associated with worse clinical outcomes. The most identified genes in carbapenemase-producing Gram-negative rods were blaKPC-2 and blaKPC-3, both related to gene co-occurrence and diverse STs in the healthcare environment. Patients had several systemic complications and poor clinical outcomes that were not associated with a particular gene.IMPORTANCEAntimicrobial resistance is a pandemic and a worldwide public health problem, especially carbapenem resistance in low- and middle-income countries. Limited data regarding the molecular characteristics and clinical outcomes of patients infected with these bacteria are available. Thus, our study described the carbapenemase-encoding genes among community- and healthcare-acquired infections. Notably, the co-occurrence of carbapenemase-encoding genes was frequently identified. We also found 78 distinct sequence types, of which two were novel Pseudomonas aeruginosa, which could represent challenges in treating these infections. Our study shows that in low and middle-income countries, such as Colombia, the burden of carbapenem resistance in Gram-negative rods is a concern for public health, and regardless of the allele, these infections are associated with poor clinical outcomes. Thus, studies assessing local epidemiology, prevention strategies (including trials), and underpinning genetic mechanisms are urgently needed, especially in low and middle-income countries.

Indian consensus on the managemeNt of carbapenem-resistant enterobacterales infection in critically ill patients II (ICONIC II)

INTRODUCTION

The rising challenge of carbapenem-resistant Enterobacterales (CRE) infections in Indian healthcare settings calls for clear clinical guidance on the management of these infections. The Indian consensus on the management of CRE infection in critically ill patients (ICONIC-II) is a follow-up of the ICONIC-I study, which was undertaken in 2019.

AREAS COVERED

A modified Delphi method was used to build expert consensus on CRE management in India, involving online surveys, face-to - face expert meetings, and a literature review. A panel of 12 experts was formed to develop potential clinical consensus statements (CCSs), which were rated through two survey rounds. The CCSs were finalized in a final face-to - face discussion. The finalized CCSs were categorized as consensus, near consensus, and no consensus.

EXPERT OPINION

The outcomes included 46 CCSs (consensus: 40; near consensus: 3; and no consensus: 3). The expert panel discussed and achieved consensus on various strategies for managing CRE infections, emphasizing the significance of existing and emerging resistance mechanisms, prompt and tailored empiric therapy, and use of combination therapies. The consensus statements based on the collective expertise of the panel can potentially assist clinicians in the management of CRE infections that lack high-level evidence.

Ceftazidime-avibactam alone or in combination with Aztreonam versus Polymyxins in the management of carbapenem-Resistant Klebsiella pneumoniae nosocomial Infections (CAPRI study): a retrospective cohort study from South India

INTRODUCTION

Carbapenem-resistant Klebsiella pneumoniae (CRKP) infections commonly cause hospital-acquired infections. The study aimed to compare the outcomes of CRKP infections between patients receiving ceftazidime avibactam +/- aztreonam and polymyxins in a hospital setting with a high prevalence of New Delhi Metallo Beta Lactamase production.

METHODS

We conducted a retrospective cohort study from January 2020 to September 2022 in critically ill adult patients admitted to a non-COVID-19 medical intensive care unit with CRKP infection. The patients were followed up for a total of 30 days or death, whichever was later.

RESULTS

Of a total of 106 patients included in the study, 65 patients received polymyxins and 41 patients received ceftazidime-avibactam +/- aztreonam. Higher 30-day mortality was noted in the polymyxin group (56.9% vs. 29.2%, P = 0.005). The mean time to event (mortality) in ceftazidime-avibactam +/- aztreonam was 23.9 + 1.5 days which was significantly higher compared to polymyxins (17.9 + 1.2 days, p = 0.006). On Cox regression analysis, after adjusting for the covariates, the hazard ratio for time to event with the use of polymyxin was 2.02 (95% CI: 1.03-3.9).

CONCLUSION

Ceftazidime-avibactam + aztreonam is possibly associated with better clinical outcomes in patients infected with CRKP.

Epidemiological characteristics of New Delhi Metallo-β-Lactamase-producing Enterobacteriaceae in the Fourth hospital of Hebei Medical University

The epidemiological characteristics of New Delhi Metallo-β-Lactamase-Producing (NDM) Enterobacteriaceae were analyzed to provide theoretical support for clarifying the distribution characteristics of carbapenem-resistant Enterobacteriaceae (CRE) in the hospital environment and early identification of susceptible patients. From January 2017 to December 2021,42 strains of NDM-producing Enterobacteriaceae were gathered from the Fourth Hospital of Hebei Medical University, primarily Escherichia coli, Klebsiella pneumoniae, and Enterobacter cloacae. The micro broth dilution method combined with the Kirby-Bauer method was used to determine the minimal inhibitory concentrations (MICs) of antibiotics. The carbapenem phenotype was detected by the modified carbapenem inactivation method (mCIM) and EDTA carbapenem inactivation method (eCIM). Carbapenem genotypes were detected by colloidal gold immunochromatography and real-time fluorescence PCR. The results of antimicrobial susceptibility testing showed that all NDM-producing Enterobacteriaceae were multiple antibiotic resistant, but the sensitivity rate to amikacin was high. Invasive surgery prior to culture, the use of excessive amounts of different antibiotics, the use of glucocorticoids, and ICU hospitalization were clinical characteristics of NDM-producing Enterobacteriaceae infection. Molecular typing of NDM-producing Escherichia coli and Klebsiella pneumoniae was carried out by Multilocus Sequence Typing (MLST), and the phylogenetic trees were constructed. Eight sequence types (STs) and two NDM variants were detected in 11 strains of Klebsiella pneumoniae, primarily ST17, and NDM-1. A total of 8 STs and 4 NDM variants were detected in 16 strains of Escherichia coli, mainly ST410, ST167, and NDM-5. For high-risk patients who have CRE infection, CRE screening should be done as soon as feasible to adopt prompt and efficient intervention measures to prevent outbreaks in the hospital.

Global prevalence and antibiotic resistance in clinical isolates of Stenotrophomonas maltophilia: a systematic review and meta-analysis

Introduction

Stenotrophomonas maltophilia is a little-known environmental opportunistic bacterium that can cause broad-spectrum infections. Despite the importance of this bacterium as an emerging drug-resistant opportunistic pathogen, a comprehensive analysis of its prevalence and resistance to antibiotics has not yet been conducted.

Methods

A systematic search was performed using four electronic databases (MEDLINE via PubMed, Embase, Scopus, and Web of Science) up to October 2019. Out of 6,770 records, 179 were documented in the current meta-analysis according to our inclusion and exclusion criteria, and 95 studies were enrolled in the meta-analysis.

Results

Present analysis revealed that the global pooled prevalence of S. maltophilia was 5.3 % [95% CI, 4.1-6.7%], with a higher prevalence in the Western Pacific Region [10.5%; 95% CI, 5.7-18.6%] and a lower prevalence in the American regions [4.3%; 95% CI, 3.2-5.7%]. Based on our meta-analysis, the highest antibiotic resistance rate was against cefuroxime [99.1%; 95% CI, 97.3-99.7%], while the lowest resistance was correlated with minocycline [4·8%; 95% CI, 2.6-8.8%].

Discussion

The results of this study indicated that the prevalence of S. maltophilia infections has been increasing over time. A comparison of the antibiotic resistance of S. maltophilia before and after 2010 suggested there was an increasing trend in the resistance to some antibiotics, such as tigecycline and ticarcillin-clavulanic acid. However, trimethoprim-sulfamethoxazole is still considered an effective antibiotic for treating S. maltophilia infections.

Molecular characterization of carbapenem resistant E. coli of fish origin reveals the dissemination of NDM-5 in freshwater aquaculture environment by the high risk clone ST167 and ST361

Aquatic environment can act as reservoir and disseminator of antimicrobial resistance and resistant pathogens. Novel high-risk carbapenem resistant E. coli (CREC) are continuously emerging worldwide; however, the occurrence of CREC in freshwater aquaculture environment is largely unexplored. To fill this gap, large scale sampling of freshwater pond sites and retail fish markets was done between Oct 2020 and Oct 2021 to investigate the CREC contamination in fish. The frequency of CREC contamination in the freshwater fish was 6.99% (95% CI: 3.78-10.20%). All the isolates were MDR and harbored carbapenemase encoding gene, bla_NDM-5 along with other antimicrobial resistance genes (ARGs), bla_TEM (64.7%), bla_CTX-M-15 (35.3%), bla_OXA-1 (5.9%), tet(A) (100%), sul1 (94.1%), qnrS (82.3%), cat1 (35.3%), and cat2 (23.5%). The isolates belonged to phylogroup C and showed low virulence gene profile. ERIC-PCR grouped the isolates into five clusters (I-V). The isolates of clusters I, II, and III were identified as ST167 (76.4%) and of cluster IV as ST361 (17.6%). This is the first report documenting the contamination of NDM-5 producing E. coli ST167 and ST361 of clinical/livestock lineage in freshwater fish from India. The bla_NDM-5 was significantly associated with ARGs, tet(A), and sul1; and plasmid replicons, IncF, IncI1, and IncP, signifying the presence of bla_NDM-5 and associated ARGs on these transferable plasmids. These findings were validated by the successful conjugal transfer of bla_NDM-5 and associated ARGs into non-CREC strain (J53). Our study highlights the ability of CREC to disseminate antimicrobial resistance which has health implications and environmental concerns.

The crisis of carbapenemase-mediated carbapenem resistance across the human-animal-environmental interface in India

Carbapenems are the decision-making antimicrobials used to combat severe Gram-negative bacterial infections in humans. Carbapenem resistance poses a potential public health emergency, especially in developing countries such as India, accounting for high morbidity, mortality, and healthcare cost. Emergence and transmission of plasmid-mediated "big five" carbapenemase genes including KPC, NDM, IMP, VIM and OXA-48-type among Gram-negative bacteria is spiralling the issue. Carbapenemase-producing carbapenem-resistant organisms (CP-CRO) cause multi- or pan-drug resistance by co-harboring several antibiotic resistance determinants. In addition of human origin, animals and even environmental sites are also the reservoir of CROs. Spillage in food-chains compromises food safety and security and increases the chance of cross-border transmission of these superbugs. Metallo-β-lactamases, mainly NDM-1 producing CROs, are commonly shared between human, animal and environmental interfaces worldwide, including in India. Antimicrobial resistance (AMR) surveillance using the One Health approach has been implemented in Europe, the United-Kingdom and the United-States to mitigate the crisis. This concept is still not implemented in most developing countries, including India, where the burden of antibiotic-resistant bacteria is high. Lack of AMR surveillance in animal and environmental sectors underestimates the cumulative burden of carbapenem resistance resulting in the silent spread of these superbugs. In-depth indiscriminate AMR surveillance focusing on carbapenem resistance is urgently required to develop and deploy effective national policies for preserving the efficacy of carbapenems as last-resort antibiotics in India. Tracking and mapping of international high-risk clones are pivotal for containing the global spread of CP-CRO.

Carbapenem-resistant gram-negative bacterial infection in intensive care unit patients: Antibiotic resistance analysis and predictive model development

In this study, we analyzed the antibiotic resistance of carbapenem-resistant gram-negative bacteria (CR-GNB) in intensive care unit (ICU) patients and developed a predictive model. We retrospectively collected the data of patients with GNB infection admitted to the ICU of the First Affiliated Hospital of Fujian Medical University, who were then divided into a CR and a carbapenem-susceptible (CS) group for CR-GNB infection analysis. Patients admitted between December 1, 2017, and July 31, 2019, were assigned to the experimental cohort (n = 205), and their data were subjected to multivariate logistic regression analysis to identify independent risk factors for constructing the nomogram-based predictive model. Patients admitted between August 1, 2019, and September 1, 2020, were assigned to the validation cohort for validating the predictive model (n = 104). The Hosmer-Lemeshow test and receiver operating characteristic (ROC) curve analysis were used to validate the model's performance. Overall, 309 patients with GNB infection were recruited. Of them, 97 and 212 were infected with CS-GNB and CR-GNB, respectively. Carbapenem-resistant Klebsiella pneumoniae (CRKP), carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenem-resistant Pseudomonas aeruginosa (CRPA) were the most prevalent CR-GNB. The multivariate logistic regression analysis results of the experimental cohort revealed that a history of combination antibiotic treatments (OR: 3.197, 95% CI: 1.561-6.549), hospital-acquired infection (OR: 3.563, 95% CI: 1.062-11.959) and mechanical ventilation ≥ 7 days (OR: 5.096, 95% CI: 1.865-13.923) were independent risk factors for CR-GNB infection, which were then used for nomogram construction. The model demonstrated a good fit of observed data (p = 0.999), with an area under the ROC curve (AUC) of 0.753 (95% CI: 0.685-0.820) and 0.718 (95% CI: 0.619-0.816) for the experimental and validation cohort, respectively. The decision curve analysis results suggested that the model has a high practical value for clinical practice. The Hosmer-Lemeshow test indicated a good fit of the model in the validation cohort (p-value, 0.278). Overall, our proposed predictive model exhibited a good predictive value in identifying patients at high risk of developing CR-GNB infection in the ICU and could be used to guide preventive and treatment measures.

In Vitro and Pre-Clinical Evaluation of Locally Isolated Phages, vB_Pae_SMP1 and vB_Pae_SMP5, Formulated as Hydrogels against Carbapenem-Resistant Pseudomonas aeruginosa

The inadequate therapeutic opportunities associated with carbapenem-resistant Pseudomonas aeruginosa (CRPA) clinical isolates impose a search for innovative strategies. Therefore, our study aimed to characterize and evaluate two locally isolated phages formulated in a hydrogel, both in vitro and in vivo, against CRPA clinical isolates. The two phages were characterized by genomic, microscopic, phenotypic characterization, genomic analysis, in vitro and in vivo analysis in a Pseudomonas aeruginosa-infected skin thermal injury rat model. The two siphoviruses belong to class Caudovirectes and were named vB_Pae_SMP1 and vB_Pae_SMP5. Each phage had an icosahedral head of 60 ± 5 nm and a flexible, non-contractile tail of 170 ± 5 nm long, while vB_Pae_SMP5 had an additional base plate containing a 35 nm fiber observed at the end of the tail. The hydrogel was prepared by mixing 5% w/v carboxymethylcellulose (CMC) into the CRPA propagated phage lysate containing phage titer 10⁸ PFU/mL, pH of 7.7, and a spreadability coefficient of 25. The groups were treated with either Phage vB_Pae_SMP1, vB_Pae_SMP5, or a two-phage cocktail hydrogel cellular subepidermal granulation tissues with abundant records of fibroblastic activity and mixed inflammatory cell infiltrates and showed 17.2%, 25.8%, and 22.2% records of dermal mature collagen fibers, respectively. In conclusion, phage vB_Pae_SMP1 or vB_Pae_SMP5, or the two-phage cocktails formulated as hydrogels, were able to manage the infection of CRPA in burn wounds, and promoted healing at the injury site, as evidenced by the histopathological examination, as well as a decrease in animal mortality rate. Therefore, these phage formulae can be considered promising for clinical investigation in humans for the management of CRPA-associated skin infections.

Phenotypic and genotypic detection of resistance mechanisms in carbapenem-resistant gram-negative bacteria isolated from Egyptian ICU patients with first emergence of NDM-1 producing Klebsiella oxytoca

Background and Objectives

Carbapenems are considered the last resort to treat several infections, particularly in intensive care units (ICUs). However, increasing carbapenem resistance is problematic because it leads to high morbidity and mortality rates. This study aimed to determine the rate of carbapenem resistance among Gram-negative bacteria collected from patients in ICUs and to identify their resistance mechanisms using phenotypic and genotypic methods.

Materials and Methods

Antimicrobial susceptibility testing was carried out using the disc diffusion method among 180 Gram-negative bacterial isolates. Productions of carbapenemases, metallo-beta-lactamases (MBLs) and the harboring of carbapenemase-encoding genes, were detected in 40 selected carbapenem-resistant Gram-negative bacteria (CR-GNB).

Results

Of 40 selected CR-GNB isolates, 28 (70%), and 20 (50%) isolates were phenotypically positive for carbapenemase, and MBL production, respectively. Furthermore, 22 (55%) showed amplification of one or more of the carbapenemase-encoding genes, including bla _NDM-1, bla _VIM-2, and bla _OXA-48. This study described the first emergence of NDM-1 producing Klebsiella oxytoca in Egyptian ICUs.

Conclusion

High incidence of CR-GNB detected in the ICUs in our study area may be attributed to the overuse of antibiotics, including carbapenems, and improper application of infection control measures. These findings confirm the need for the application of a strict antibiotic stewardship program.

The Emergence of Carbapenem-Resistant Gram-Negative Bacteria in Mizoram, Northeast India

(Background) Numerous reports on carbapenem resistance in different parts of India have been published, yet there are insufficient studies on the prevalence of antibiotic resistance in the northeast region of the country. This study evaluated the emergence of carbapenem resistance in the clinical isolates collected in Mizoram. (Results) A total of 141 Gram-negative clinical isolates were collected from the two hospitals, including the Civil Hospital in Lunglei and the Synod Hospital in Aizawl. The isolates include Escherichia coli (n = 62, 43.9%), Klebsiella spp. (n = 43, 30.4%), Pseudomonas aeruginosa (n = 9, 6.3%), Serratia marcescens (n = 3, 2.1%), Proteus mirabilis (n = 2, 1.4%), Shigella spp. (n = 4, 2.8%), Enterobacter spp. (n = 6, 4.2%) and Acinetobacter spp. (n = 12, 8.5%). The isolates were found to be resistant to meropenem (11%), colistin (48%), tigecycline (25%) and cefotaxime (50%). A total of four E. coli and one Shigella sonnei encoded the blaOXA-48-like gene. The blaCTX-M-1 gene was detected in 13 isolates, of which eight were E. coli, two Shigella flexneri, and one isolates each of K. pneumoniae, K. oxytoca and Shigella sonnei, respectively. (Conclusion) Carbapenem-resistant Enterobacteriaceae are common among other parts of India, despite limited access to antibiotics, the emergence of resistance in the northeastern region is worrying.

Report on carbapenemase-producing rare sequence types of Escherichia coli and Enterobacter hormaechei

Introduction and Aim: Carbapenem Resistant Enterobacteriaceae (CRE) have emerged at an alarming rate. Multi locus sequence typing (MLST) is an important parameter for identifying drug resistant organisms.  The present study was carried out for elucidating the mechanisms of CRE and MLSTs associated with CRE. Materials and Methods: CRE (n=14) were obtained from various clinical samples and subjected to Rapidec Carba NP (CNP) test and multiplex polymerase chain reaction (M-PCR) and five isolates proceeded for whole genome sequencing (WGS). ?-lactamase (bla) genes were analysed using Resfinder and CARD tool. Bioinformatics tools: mlplasmids, plasmid finder, mobile element finder, and Center for Genomic Epidemiology (CGE) toolbox were used. Results: All isolates (n=14) were positive for CNP and bla genes using M-PCR. Isolates (J21, J22, J23, J27) were identified as Escherichia coli while (J34) was Enterobacter hormaechei. MLST showed E. coli isolates (J21& J22) as ST648; E. coli (J23) was ST940; E. coli (J27) was ST 2851, and E. hormaechei (J34) was closest to ST1325. Genes blaTEM, blaNDM & blaampC were found to be present in all isolates; blaCTX-M was present in all E. coli isolates but not in E. hormaechei. blaOXA was present in E. coli (J23) and in E. hormaechei (J34); while ESBL blaSFO-1 in E. hormaechei (J34). Conclusion: ESBLs (blaTEM & blaCTXM) and metallo beta-lactamase -MBL (blaNDM) cause carbapenem resistance in rare sequence types of E. coli while; ESBL (blaSFO-1) and MBL (blaNDM) cause carbapenem resistance in                             E. hormaechei.

Relationship Between Multidrug-Resistant Enterobacterales and Obesity in Older Adults

Purpose

The objective of our study was to determine if obesity is associated with the presence of multidrug-resistant (MDR) bacteria among Enterobacterales.

Patients and Methods

This two-center cohort study included adult hospitalized patients with at least one specimen sampled from any site for bacterial culture yielding an Enterobacterales bacterial species from November 2016 to May 2017. Study groups were stratified by obesity status based on body mass index <30 kg/m² (non-obese) and ≥30 kg/m² (obese). The primary outcome was the presence of gram-negative MDR bacteria defined as presumptive extended-spectrum beta-lactamase (ESBL)-producing Enterobacterales (ceftriaxone resistance) or carbapenem-resistant Enterobacterales (CRE). A multivariable logistic regression model was fit to estimate the adjusted odds ratio while controlling for potential confounders.

Results

A total of 366 patients, 238 non-obese and 128 obese, were included. The most common gram-negative bacterial species identified was Escherichia coli (64.2%). There was a higher proportion of gram-negative MDR bacteria in obese versus non-obese patients (18.8 versus 11.3%, P=0.057). Obesity was independently associated with gram-negative MDR bacteria after controlling for confounders (adjusted odds ratio, 1.92; 95% CI 1.03–3.60). The association did not significantly vary by diabetes status (interaction term P=0.792).

Conclusion

Among older adult hospitalized patients, obesity was independently associated with the presence of a gram-negative MDR bacteria (presumptive ESBL or CRE) in a culture.

Genetic Characterisation of Colistin Resistant Klebsiella pneumoniae Clinical Isolates From North India

Background

Increasing use of colistin has led to the world-wide emergence of mobile colistin resistant gene (mcr). The present study aimed to identify and characterise mcr and other drug-resistant genes in colistin resistant Klebsiella pneumoniae clinical isolates.

Methods

Twenty-two colistin resistant K. pneumoniae were analysed for mcr and other drug-resistant genes, efflux pumps, and virulence genes, and for their biofilm forming ability. Pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) were performed for all mcr-1 positive isolates. S1-PFGE and Southern hybridisation were performed for localisation of mcr-1 and bla_NDM.

Results

Nineteen colistin resistant K. pneumoniae harboured mcr-1 and 3 had mgrB disruption. All isolates harboured bla_OXA-48-type and ESBL genes; eight strains (five with mcr-1 and three with mgrB disruption) co-harboured bla_NDM. Efflux pumps genes AcrAB and mdtK were detected in all 22 and tol-C in 21 isolates. Virulence-related genes entB and irp-1 were detected in all 22, mrkD in 20, and fimH-1 in 18 isolates; 11 isolates were strong biofilm producers. PFGE clustered mcr-1 positive isolates into eight groups based on ≥90% similarity; MLST revealed diverse sequence types, predominant being ST-15 (n = 4) and ST-16 (n = 4). Both mcr-1 and bla_NDM were localised on plasmid and chromosome; mcr-1 was present on IncFII type and bla_NDM on IncFIB and IncA/C type plasmids.

Conclusions

Colistin resistance in K. pneumoniae was predominantly mediated by mcr-1. Co-existence of colistin, carbapenem, and other drug-resistant genes along with efflux pumps indicates towards enormous genomic plasticity in K. pneumoniae with ability to emerge as super-spreader of drug-resistance.

Clinical and Demographic Characteristics of Patients With a New Diagnosis of Carriage or Clinical Infection With Carbapenemase-Producing Enterobacterales: A Retrospective Study

Background: To examine the clinical, demographic, and microbiologic characteristics of new rectal carbapenemase-producing carbapenem-resistant Enterobacterales (CP-CRE) carriers vs. those with a clinical infection, hospitalized at Padeh-Poriya Medical Center between 2014 and 2017 and to examine the susceptibility profiles of isolates from clinical infections.

Methods: In this retrospective, chart analysis, demographic and clinical data were collected from medical charts of 175 adult patients with either new- onset carbapenemase-producing Enterobacterales (CPE) carriage or clinical CPE infection. Collected data included age, ethnic group, place of residence, hospitalizations in the past 90 days, and 30-day mortality. Microbiological analyses considered bacterial genus, molecular resistance mechanism and antibiotic susceptibility.

Results: A significantly higher percentage (42.4%) of CPE carriers were long-term care facility residents, and had been recently hospitalized (56.3%), as compared to patients with clinical CPE infection (29.2 and 45.9%, respectively). Additionally, we noted a high (58.3%) acquision of CPE in our hospital. The most common bacterial isolate was K. pneumoniae and the most common resistance mechanism was Klebsiella pneumoniae (K. pneumoniae) carbapenemases (KPC). High susceptibility rates to amikacin and chloramphenicol were also noted.

Conclusions: This study reaffirmed the importance of CPE screening and infection control measures. The observed antibiotic susceptibility profile suggests amikacin and chloramphenicol as potential treatments for CPE infection.

Carbapenemase Producers Among Extensive Drug-Resistant Gram-Negative Pathogens Recovered from Febrile Neutrophilic Patients in Egypt

Purpose

This study aimed to detect the prevalence of carbapenemase producers (CPs) among extensive drug-resistant (XDR)-carbapenemase producing Gram-negative bacteria (GNB) recovered from various clinical specimens of hospitalized neutrophilic febrile patients in two major tertiary care hospitals in Egypt.

Methods

Standard methods were used to evaluate the antimicrobial susceptibility of clinical isolates according to the guidelines of the Clinical and Laboratory Standards Institute (CLSI). Phenotypic and genotypic analysis of CPs were carried out and statistically analyzed using standard methods.

Results

Three hundred and forty-two GNB were obtained from 342 clinical specimens during the period of the study, where 162 (47%) were enterobacterial isolates, including, 63 (18.4%) Escherichia coli, 87 (25.4%) Klebsiella spp., 5 (1.46%) Enterobacter cloacae, 5 (1.46%) Salmonella spp. and 2 (0.6%) Proteus and 180 (53%) were non-fermentative bacilli including, 129 (37.7%), Acinetobacter baumannii, and 51 (14.9%), Pseudomonas spp. Out of the 342 GNB, 188 (54.9%) isolates were multi-drug resistant (MDR). Of these, 52 (27.6%) were XDR as well as CPs as confirmed phenotypically. The MIC of imipenem against the XDR GNB against showed either low (11 isolates; 21.1%; MIC range =4–32 µg/mL) or high levels of resistance (41 isolates; 78.8%; MIC range = 64-≥1024). The most prevalent carbapenem resistance (CR) genes were blaKPC (63.5%) followed by blaOXA-48 (55.7%) and blaVIM (28.8%). No significant association could be observed between the MIC level and the presence of CR genes (P value >0.05).

Conclusion

High prevalence of MDR (54.9%) and XDR (27.6%) GNB pathogens associated with high levels of resistance to carbapenems were observed. All XDR GNB were CPs and tested positive for at least one of the CR genes. However, most of them (78.8%) showed a high level of CR (MIC range = 64-≥1024) with no significant association with the CR genes.

Metallo-β-Lactamases: Structure, Function, Epidemiology, Treatment Options, and the Development Pipeline

Modern medicine is threatened by the global rise of antibiotic resistance, especially among Gram-negative bacteria. Metallo-β-lactamase (MBL) enzymes are a particular concern and are increasingly disseminated worldwide, though particularly in Asia. Many MBL producers have multiple further drug resistances, leaving few obvious treatment options. Nonetheless, and more encouragingly, MBLs may be less effective agents of carbapenem resistance in vivo, under zinc limitation, than in vitro Owing to their unique structure and function and their diversity, MBLs pose a particular challenge for drug development. They evade all recently licensed β-lactam-β-lactamase inhibitor combinations, although several stable agents and inhibitor combinations are at various stages in the development pipeline. These potential therapies, along with the epidemiology of producers and current treatment options, are the focus of this review.

Polymyxins and Bacterial Membranes: A Review of Antibacterial Activity and Mechanisms of Resistance

Following their initial discovery in the 1940s, polymyxin antibiotics fell into disfavor due to their potential clinical toxicity, especially nephrotoxicity. However, the dry antibiotic development pipeline, together with the rising global prevalence of infections caused by multidrug-resistant (MDR) Gram-negative bacteria have both rejuvenated clinical interest in these polypeptide antibiotics. Parallel to the revival of their use, investigations into the mechanisms of action and resistance to polymyxins have intensified. With an initial known effect on biological membranes, research has uncovered the detailed molecular and chemical interactions that polymyxins have with Gram-negative outer membranes and lipopolysaccharide structure. In addition, genetic and epidemiological studies have revealed the basis of resistance to these agents. Nowadays, resistance to polymyxins in MDR Gram-negative pathogens is well elucidated, with chromosomal as well as plasmid-encoded, transferrable pathways. The aims of the current review are to highlight the important chemical, microbiological, and pharmacological properties of polymyxins, to discuss their mechanistic effects on bacterial membranes, and to revise the current knowledge about Gram-negative acquired resistance to these agents. Finally, recent research, directed towards new perspectives for improving these old agents utilized in the 21st century, to combat drug-resistant pathogens, is summarized.

Detection of various beta-Lactamases in Escherichia coli and Klebsiella sp.: A study from Tertiary Care Centre of North India

Objective

The emergence of carbapenem-resistant Escherichia coli and Klebsiella species is a global threat. We aimed to compare two phenotypic methods and evaluate the genotypic method for the detection of beta-lactamases produced by E. coli and Klebsiella spp.

Materials and Methods

One hundred and twenty-six E. coli and Klebsiella isolates were examined for phenotypic production of beta-lactamases by using disc diffusion, combined disc test (CDT) and modified carbapenem inactivation method (mCIM). All strains were also studied for the presence of various genes by polymerase chain reaction.

Results

Out of 126 isolates, 96% of the isolates were extended-spectrum β-lactamase (ESBL) producers based on the presence of various ESBL genes. CDT method showed higher number of total (89%) carbapenemases in comparison to mCIM (81%). Among carbapenemases none of the isolates were Klebsiella pneumoniae carbapenemase producer by CDT, while 69% isolates were metallo-beta-lactamase (MBL) producers. Another method, mCIM/ethylene diamine tetraacetic acid mCIM showed 100% agreement for MBL detection. As regards, AmpC and class D carbapenemases; 0.04% and 16% positivity was detected, respectively, based on CDT method. Molecular analysis revealed 91% of the isolates harbouring carbapenemase genes. blaNDMwas the most common gene detected followed byblaOXA-48. Nine of the blaNDM-positive isolates also possessed blaOXA-48gene.

Conclusion

Our finding shows high percentages of ESBL and carbapenemases in E. coli and Klebsiella spp. Among phenotypic methods, CDT seems to be a better choice as prevalence of carbapenemases shows lots of variation in our country. For Class B enzymes, both CDT and mCIM/eCIM can be used in the routine laboratories.

Evaluation of Resistance Mechanisms in Carbapenem-Resistant Enterobacteriaceae

BACKGROUND

Carbapenem-resistant Enterobacteriaceae (CRE) is a major concern leading to morbidity and mortality in the world. CRE often is becoming a cause of therapeutic failure in both hospital and community-acquired infections.

AIM

This study aimed to investigate the resistance mechanisms of CRE by phenotypic and molecular methods.

MATERIALS AND METHODS

Sixty CRE (50 Klebsiella pneumoniae, 6 Escherichia coli, and 4 Enterobacter spp.) were isolated from October 2018 to June 2019. Antimicrobial susceptibility testing was carried out using phenotypic methods. The carbapenem resistance mechanisms including efflux pump hyperexpression, AmpC overproduction, carbapenemase genes, and deficiency in OmpK35 and OmpK36 were determined by phenotypic and molecular methods, respectively.

RESULTS

Sixty CRE (50 Klebsiella pneumoniae, 6 Escherichia coli, and 4 Enterobacter spp.) were isolated from October 2018 to June 2019. Amikacin was found to be the most effective drug against CRE isolates. All isolates were resistant to imipenem and meropenem by the micro-broth dilution. AmpC overproduction was observed in all Enterobacter spp. and three K. pneumoniae isolates. No efflux pump activity was found. Carba NP test and Modified Hodge Test could find carbapenemase in 59 (98%) isolates and 57 (95%) isolates, respectively. The most common carbapenemase gene was bla OXA-48-like (72.8%) followed by bla NDM (50.8%), bla IMP (18.6%), bla VIM (11.8%), and bla KPC (6.7%). The ompK35 and ompK36 genes were not detected in 10 and 7 K. pneumoniae isolates, respectively.

CONCLUSION

The amikacin is considered as a very efficient antibiotic for the treatment of CRE isolates in our region. Carbapenemase production and overproduction of AmpC are the main carbapenem resistance mechanisms in CRE isolates. Finally, Carba NP test is a rapid and reliable test for early detection of carbapenemase-producing isolates.

Veterinary informatics: forging the future between veterinary medicine, human medicine, and One Health initiatives-a joint paper by the Association for Veterinary Informatics (AVI) and the CTSA One Health Alliance (COHA)

Objectives

This manuscript reviews the current state of veterinary medical electronic health records and the ability to aggregate and analyze large datasets from multiple organizations and clinics. We also review analytical techniques as well as research efforts into veterinary informatics with a focus on applications relevant to human and animal medicine. Our goal is to provide references and context for these resources so that researchers can identify resources of interest and translational opportunities to advance the field.

Methods and Results

This review covers various methods of veterinary informatics including natural language processing and machine learning techniques in brief and various ongoing and future projects. After detailing techniques and sources of data, we describe some of the challenges and opportunities within veterinary informatics as well as providing reviews of common One Health techniques and specific applications that affect both humans and animals.

Discussion

Current limitations in the field of veterinary informatics include limited sources of training data for developing machine learning and artificial intelligence algorithms, siloed data between academic institutions, corporate institutions, and many small private practices, and inconsistent data formats that make many integration problems difficult. Despite those limitations, there have been significant advancements in the field in the last few years and continued development of a few, key, large data resources that are available for interested clinicians and researchers. These real-world use cases and applications show current and significant future potential as veterinary informatics grows in importance. Veterinary informatics can forge new possibilities within veterinary medicine and between veterinary medicine, human medicine, and One Health initiatives.

Molecular Epidemiology of and Risk Factors for Extensively Drug-Resistant Klebsiella pneumoniae Infections in Southwestern China: A Retrospective Study

Background: The increasing prevalence of extensively drug-resistant Klebsiella pneumoniae (XDR-KP) poses a serious threat to clinical anti-infective treatment. This retrospective study assessed the molecular epidemiology of and risk factors for infections with XDR-KP to investigate the mechanism of drug resistance and the epidemiological characteristics.

Methods: A retrospective 1:2 case-control study was conducted at Chongqing Renji Affiliated Hospital of the Chinese Academy of Sciences University from January 2015 to December 2017. A total of 69 non-repetitive XDR-KP strains were collected. Patients infected with XDR-KP comprised the case group, and 138 matched patients with non-XDR-KP infection at the same site comprised the control group. The chi-square test and logistic regression were performed to evaluate the related risk factors. Molecular typing was performed by multilocus sequence typing (MLST). Potential resistance genes were detected by polymerase chain reaction (PCR) and sequencing. Predictors of 28-day mortality in patients with XDR-KP infection were also identified in our study.

Results: Only tigecycline and polymyxin B showed favorable in vitro drug sensitivity tests. These XDR-KP strains had a high prevalence rate (n = 66, 95.7%) of carbapenemase-related drug resistance genes. Among them, KPC-2 was the most frequently detected gene (n = 52, 75.4%). Particularly, all of the isolates harbored multiple drug resistance genes. Epidemiological analysis showed that fifty-eight XDR-KP isolates were resistant strains with the ST-11 genotype. Multivariate logistic regression analysis showed that ICU admission (OR: 3.28, 95% CI: 1.66–6.49, P < 0.001), tracheal cannula (OR: 3.16, 95% CI: 1.48–6.76, P = 0.003), and carbapenem exposure (OR: 3.16, 95% CI: 1.25–7.98, P = 0.015) were independent risk factors for XDR-KP infection. Solid tumors (OR: 7.22, 95% CI: 1.84–28.34, P = 0.005) and septic shock (OR: 9.46, 95% CI: 2.00–44.72, P = 0.005) were independent risk factors for 28-day mortality from XDR-KP infection.

Conclusion: This study showed that XDR-KP isolates were highly resistant and exhibited clonal transmission. ST11 was the predominant epidemic type of XDR-KP producing KPC-2 in Southwestern China. Physicians should be aware of these high-risk patients with notable predictive factors for XDR-KP infection. These findings may provide some recommendation for the diagnosis and treatment of patients infected with XDR-KP strains in Southwestern China.