OXA-48-like carbapenemases: the phantom menace

Emergence of carbapenemase-producing and colistin resistant Klebsiella pneumoniae ST101 high-risk clone in Turkey

Carbapenemase-producing and colistin resistant Klebsiella pneumoniae has become a worldwide healthcare problem. This study describes molecular characterization of carbapenemase-producing and colistin resistant clinical K. pneumoniae isolates.A total of 93 non-replicate carbapenem and colistin resistant K. pneumoniae were recovered from clinical specimens in a university hospital during 2017-2019. Detection of blaOXA-48, blaKPC, blaNDM-1, blaIMP, blaVIM-1 and mcr-1, -2, -3, -4, -5, -6, -7, and -8 genes was performed by PCR. The bacterial isolates were assigned to clonal lineages by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).All isolates harbored blaOXA-48 and only two isolates harbored blaOXA-48, and blaNDM-1 genes together. In colistin resistant K. pneumoniae, mcr-1 was detected in two (2.1%) isolates. Ninety three isolates of K. pneumoniae were categorized into three clusters and five pulsotypes. MLST revealed two different sequence types, ST101 (89/93) and ST147 (4/93).In our study ST101 was found to be a significantly dominant clone carrying blaOXA-48 and among our strains a low frequency of mcr-1 gene was determined. The emergence of colistin resistance was observed in K. pneumoniae ST101 isolates. ST101 may become a global threat in the dissemination of carbapenem and colistin resistance.

Antibiogram and Genetic Characterization of Carbapenem-Resistant Gram-Negative Pathogens Incriminated in Healthcare-Associated Infections

Purpose

Carbapenems are considered the most efficient antibiotic used in the treatment of nosocomial infections. Carbapenem-resistant Gram-negative rods are becoming a serious hazard in hospitals threatening public health. The aim of the current study was to investigate the prevalence of carbapenem-resistant Gram-negative pathogens incriminated in healthcare-associated infections, along with antimicrobial resistance profiles, carbapenemase and metallo-β-lactamase production, and their molecular characterization.

Methods

A total of 186 clinical specimens were collected from 133 patients at various hospitals in Cairo, Egypt. The obtained specimens were subjected to bacteriological examination, antimicrobial susceptibility testing, detection of carbapenemase production using the modified Hodge test (MHT), the metallo-β-lactamase production using the EDTA combined disc test (CDT), and PCR-based detection of the bla _KPC and bla _GES resistance genes. The identification of the highly resistant retrieved isolates was then confirmed by 16S rRNA gene sequencing.

Results

The most common isolated Gram-negative species was Klebsiella pneumoniae (40.9%), followed by Acinetobacter baumannii (18.8%), Pseudomonas aeruginosa (17.3%), Escherichia coli (15.4%), Enterobacter aerogenes (5.3%), and Proteus mirabilis (2.4%). The prevalence of carbapenem-resistant isolates was 36.1% (n=75). However, 86.5% of the recovered clinical isolates were susceptible to colistin. The MHT revealed that 33.6% (n=70) of the tested strains were positive for carbapenemase production, while the CDT showed that 33.17% (n=69) of the examined strains were metallo-β-lactamase producers. The PCR revealed that 98.6% (74/75) of the tested strains possessed the bla _KPC gene; moreover, 97.3% (73/75) of the examined strains harbored the bla _GES gene.

Conclusion

This study displayed the emergence of carbapenem-resistant Gram-negative pathogens incriminated in healthcare-associated infections. The accurate identification of carbapenem-resistant bacterial pathogens is pivotal for the treatment of patients, in addition to propelling appropriate contamination control measures to restrain the fast spread of such pathogens. Colistin showed a potent in vitro antimicrobial activity against the carbapenem-resistant strains.

Investigation on the Genetic Signatures of Antibiotic Resistance in Multi-Drug-Resistant Klebsiella Pneumoniae Isolates From National Guard Hospital, Riyadh

Introduction Despite a large number of antibiotics available to treat Klebsiella (K.) pneumoniae (KP), resistance against these antibiotics is ever-increasing and has now become a global threat to human life. The most frequently observed resistant genes in Klebsiella pneumoniae are CTX-M, OXA-48, IMP, and NDM; some are clone-specific while others form a reservoir for infection. Methods Matrix-assisted laser desorption ionization-time of flight (MALDI-TOF) was employed for the identification of the pathogens and automated VITEK-2 (bioMérieux, Marcy-l'Étoile, France) was used for minimum inhibitory concentration (MIC) determination, followed by polymerase chain reaction (PCR) amplification of target genes and Sanger sequencing of amplicons. Results Forty-three out of 50 isolates (86%) were OXA gene-positive, and 49 out of 50 (98%) isolates were CTX-M gene positive. Two phenotypes of OXA were identified in 33 samples sequenced, OXA-505 (70%) and OXA-232 (30%). Sixteen isolates (32%) were positive for NDM-1. Twelve isolates were positive for both OXA and NDM. Multilocus sequence typing (MLST) on these isolates showed that they were distributed in 12 sequence types (STs). Thirty-six out of 50 were grouped in four clonal complexes. ST-14 was the predominant genotype. Conclusion This study has revealed that CTX-M-15 is the most common extended-spectrum beta-lactamase (ESBL) present in almost all isolates. The study also shows the presence of OXA as the main carbapenemase gene, alone or in combination with other carbapenemases such as NDM-1. Multilocus sequence typing revealed the incidence of polyclonal KP pool with ST-14, ST-29, ST-307, and ST-15 being the predominant ones.

WGS characterization of MDR Enterobacterales with different ceftolozane/tazobactam susceptibility profiles during the SUPERIOR surveillance study in Spain

Objectives

To analyse by WGS the ceftolozane/tazobactam (C/T) resistance mechanisms in Escherichia coli and Klebsiella spp. isolates recovered from complicated intra-abdominal and urinary tract infections in patients from Spanish ICUs (SUPERIOR surveillance study, 2016-17).

Methods

The clonal relatedness, the resistome and the virulome of 45 E. coli and 43 Klebsiella spp. isolates with different C/T susceptibility profiles were characterized.

Results

In E. coli, two (C/T susceptible) carbapenemase producers (VIM-2-CC23, OXA-48-ST38) were detected. The most relevant clone was ST131-B2-O25:H4-H30 (17/45), particularly the CTX-M-15-ST131-H30-Rx sublineage (15/17). ST131 strains were mainly C/T susceptible (15/17) and showed an extensive virulome. In non-ST131 strains (28/45), CTX-M enzymes [CTX-M-14 (8/24); CTX-M-15 (6/24); CTX-M-1 (3/24); CTX-M-32 (2/24)] were found in different clones. C/T resistance was detected in non-clonal E. coli isolates (13%, 6/45) with ESBL (4/6) and non-ESBL (2/6) genotypes. Among Klebsiella spp., Klebsiella pneumoniae (42/43) and Klebsiella michiganensis (1/43) species were identified; 42% (18/43) were carbapenemase producers and 58% showed a C/T resistance phenotype (25/43). OXA-48-ST11 (12/18), OXA-48-ST392 (2/18), OXA-48-ST15 (2/18), NDM-1-ST101 (1/18) and OXA-48+VIM-2-ST15 (1/18) isolates were found, all C/T resistant. Correlation between carbapenemase detection and resistance to C/T was demonstrated (P < 0.001). In non-carbapenemase-producing K. pneumoniae (25/43), C/T resistance (28%, 7/25) was detected in ESBL (3/7) and AmpC (2/7) producers. Overall, an extensive virulome was found and was correlated with carbapenemase carriage (P < 0.001) and C/T resistance (P < 0.05), particularly in OXA-48-ST11 strains (P < 0.05).

Conclusions

Prediction of antimicrobial susceptibility profiles using WGS is challenging. Carbapenemase-encoding genes are associated with C/T resistance in K. pneumoniae, but other resistance mechanisms might be additionally involved.

Spectrum of Bacterial Colonization in Patients Hospitalized for Treatment of Multidrug-Resistant Tuberculosis

This study investigated the bacterial colonization in patients admitted for treatment of drug-resistant tuberculosis in a specialized TB hospital. Identification and antimicrobial susceptibility testing of bacterial isolates (n = 62) from nasal, groin, and rectal swabs [patient cohort (n = 37)] were determined by the VITEK-MS system. Resistance gene analysis was by PCR and DNA sequencing. Molecular typing of Klebsiella pneumoniae isolates was by Multilocus Sequencing Typing (MLST). Patients (n = 13/37; 35%) were colonized by multidrug-resistant (MDR) bacteria (ESBL and MRSA) on admission. Of the 24 patients who were not colonized by MDR bacteria on admission, 46% (17/37) became colonized by MDR bacteria within 1 month of admission, mostly with ESBL-producing Enterobacteriales and resistance to aminoglycosides and fluoroquinolones. ESBL Escherichia coli (41/62; 66%) and K. pneumoniae (14/62; 23%) predominated. Genes encoding for ESBLs (bla_CTX-M-14, bla_CTX-M-15, bla_SHV-28, bla_OXA-1, and bla_OXY-2) and plasmid-mediated quinolone resistant genes (qnrB1, qnrB4, and qnrB10) were detected. MLST revealed genetic diversity among the K. pneumoniae isolates from hospitalized patients. This study provides insight into bacterial pathogen colonization in hospitalized TB patients with the first occurrence of the qnrB4 and qnrB10 genes and co-expression of genes: qnrB4+aac(6')-lb-cr, qnrB10+aac(6')-lb-cr, qnrB4+qnrS1, and qnrB10+qnrS1 in fluoroquinolone-resistant E. coli isolates within South Africa. However, the source and colonization routes of these isolates could not be determined.

The Hydric Environment: A Hub for Clinically Relevant Carbapenemase Encoding Genes

Carbapenems are β-lactams antimicrobials presenting a broad activity spectrum and are considered as last-resort antibiotic. Since the 2000s, carbapenemase producing Enterobacterales (CPE) have emerged and are been quickly globally spreading. The global dissemination of carbapenemase encoding genes (CEG) within clinical relevant bacteria is attributed in part to its location onto mobile genetic elements. During the last decade, carbapenemase producing bacteria have been isolated from non-human sources including the aquatic environment. Aquatic ecosystems are particularly impacted by anthropic activities, which conduce to a bidirectional exchange between aquatic environments and human beings and therefore the aquatic environment may constitute a hub for CPE and CEG. More recently, the isolation of autochtonous aquatic bacteria carrying acquired CEG have been reported and suggest that CEG exchange by horizontal gene transfer occurred between allochtonous and autochtonous bacteria. Hence, aquatic environment plays a central role in persistence, dissemination and emergence of CEG both within environmental ecosystem and human beings, and deserves to be studied with particular attention.

Transcriptional Analysis of IncFrepB-Mediated blaOXA-48-Positive Plasmid Characterized from Escherichia coli ST448

Objectives: To investigate the transcriptional response of bla_OXA-48 and the copy number alteration of IncF_repB plasmid carrying bla_OXA-48 under an antibiotic concentration gradient. Methods: Escherichia coli strains harboring bla_OXA-48 on an IncFrep_B plasmid were isolated from Silchar Medical College and Hospital, Silchar, India. Sequence type and common resistance determinants were determined by PCR assay. Plasmid copy number alteration and the transcriptional expression of bla_OXA-48 under different antibiotic pressures were determined by quantitative real-time PCR, and the relative fold change was measured by the ΔΔCT method. Results and Conclusion: The plasmid that carried bla_OXA-48 in E. coli ST448 was characterized as IncFrep_B and found to be conjugatively transferable. The isolates were found to coexist with bla_NDM-1 within the IncX3-type plasmid. It was observed that the copy number and transcriptional response of bla_OXA-48 were directly proportional to the increasing concentration of meropenem and ertapenem, whereas in the case of imipenem, it was reversed. The identification of bla_OXA-48 through IncF_repB-type plasmid in this study indicates the potential route of spread of this resistance determinant in this area and also the insights we gained from the transcriptional changes of bla_OXA-48 in response to different antibiotic pressures could also facilitate the development of novel or alternative therapeutic options needed for multidrug-resistant infections.

blaOXA -731 , a new chromosome-encoded blaOXA -48 -like variant in Shewanella sp. from the aquatic environment in Myanmar

Shewanella sp., the progenitors of bla_OXA-48 -like genes are increasingly reported with the possession of different bla_OXA-48 -like variants. This study aims to characterize bla_OXA-731 , a new variant of a bla_OXA-48 -like gene identified in Shewanella sp. isolated from the aquatic environment in Myanmar. Phylogenetic analysis of the bla_OXA-731 sequence with other bla_OXA-48 -like variants showed that it has the highest nucleotide identity of 86.09% with bla_OXA-48 . However, the active site motifs in OXA-731 were 100% identical to that in OXA-48. Whole-genome sequencing analysis showed that bla_OXA-731 is not surrounded by any mobile genetic elements. The genetic context of bla_OXA-731 was found as similar to other bla_OXA-48 -like genes previously identified in Shewanella sp. S1 nuclease pulsed-field gel electrophoresis followed by Southern blotting confirmed the location of bla_OXA-731 in the chromosome of the Shewanella genome. Cloning and expression studies showed that OXA-731 has β-lactamase activity similar to OXA-48 and OXA-181, but it has no significant carbapenemase activity. Our results showed the significance of bla_OXA-48 -like-carrying Shewanella sp. in the spreading of bla_OXA-48 -like genes in the community.

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.

Resistance to Ceftazidime/Avibactam plus Meropenem/Vaborbactam When Both Are Used Together Is Achieved in Four Steps in Metallo-β-Lactamase-Negative Klebsiella pneumoniae

Serine β-lactamases are dominant causes of β-lactam resistance in Klebsiella pneumoniae isolates. Recently, this has driven clinical deployment of the β-lactam-β-lactamase inhibitor pairs ceftazidime/avibactam and meropenem/vaborbactam. We show that four steps, i.e., ompK36 and ramR mutation plus carriage of OXA-232 and KPC-3-D178Y variant β-lactamases, confer ceftazidime/avibactam and meropenem/vaborbactam resistance when both pairs are used together. These findings have implications for decision making about sequential and combinatorial use of these β-lactam-β-lactamase inhibitor pairs to treat K. pneumoniae infections.

Shedding of OXA-181 carbapenemase-producing Escherichia coli from companion animals after hospitalisation in Switzerland: an outbreak in 2018

Background

Carbapenem-resistant Enterobacteriaceae pose a serious threat to public health worldwide, and the role of companion animals as a reservoir is still unclear.

Aims

This 4-month prospective observational study evaluated carriage of carbapenem-resistant Enterobacteriaceae at admission and after hospitalisation in a large referral hospital for companion animals in Switzerland.

Methods

Rectal swabs of dogs and cats expected to be hospitalised for at least 48 h were taken from May to August 2018 and analysed for the presence of carbapenem-resistant Enterobacteriaceae using selective agar plates. Resistant isolates were further characterised analysing whole genome sequences for resistance gene and plasmid identification, and ad hoc core genome multilocus sequence typing.

Results

This study revealed nosocomial acquisition of Escherichia coli harbouring the carbapenemase gene bla_OXA-181, the pAmpC cephalosporinase gene bla_CMY-42 as well as quinolone resistance associated with qnrS1 and mutations in the topoisomerases II (GyrA) and IV (ParC). The bla_OXA-181 and qnrS1 genes were identified on a 51 kb IncX3 plasmid and bla_CMY-42 on a 47 kb IncI1 plasmid. All isolates belonged to sequence type ST410 and were genetically highly related. This E. coli clone was detected in 17 of 100 dogs and four of 34 cats after hospitalisation (21.6%), only one of the tested animals having tested positive at admission (0.75%). Two positive animals were still carriers 4 months after hospital discharge, but were negative after 6 months.

Conclusions

Companion animals may acquire carbapenemase-producing E. coli during hospitalisation, posing the risk of further dissemination to the animal and human population and to the environment.

An MLST approach to support tracking of plasmids carrying OXA-48-like carbapenemase

OBJECTIVES

The prevalence of infections caused by OXA-48-like carbapenemase-producing organisms in Ireland has increased dramatically since 2011 and is an urgent public health issue. Genome-based high-resolution genotyping was used to analyse clinical isolates submitted to the Irish Carbapenemase-Producing Enterobacteriaceae Reference Laboratory Service for a 13 month period (2016-17).

METHODS

A total of 109 OXA-48-producing non-duplicate clinical isolates from 16 submitting centres were sequenced. Using a gene-by-gene approach, isolate genomes were characterized by MLST and core genome MLST, and the presence of antimicrobial resistance determinants was determined. Reference mapping and a novel plasmid MLST-type approach was applied to determine plasmid background.

RESULTS

The OXA-48-like-producing isolates were Escherichia coli (n = 56), Klebsiella spp. (n = 46) and Enterobacter cloacae (n = 7). Amongst the E. coli isolates there were 37 different STs and amongst the Klebsiella spp. isolates there were 27 different STs. blaOXA-48 was present in 105/109 (96.3%) of isolates. Based on mapping analysis and detection of the pOXA-48 IncL-type plasmid replicon and backbone genes, a pOXA-48-like plasmid was identified in 93/109 isolates (85.3%). The remaining isolates (n = 16; 14.7%) harboured blaOXA-48-like genes in unknown environments. Using a gene-by-gene approach two pOXA-48-like plasmid groups with 2/71 pOXA-48-like locus differences between them were identified.

CONCLUSIONS

In Ireland we found a diversity of genotypes associated with OXA-48-like-producing clinical isolates with the IncL pOXA-48 plasmid type predominating as the blaOXA-48 genetic environment. A plasmid MLST approach can rapidly identify plasmids associated with outbreaks and monitor spread of types temporally and geographically.

Clinical and Economic Outcomes of Genome Sequencing Availability on Containing a Hospital Outbreak of Resistant Escherichia coli in Australia

OBJECTIVES

To evaluate the outbreak size and hospital cost effects of bacterial whole-genome sequencing availability in managing a large-scale hospital outbreak.

METHODS

We built a hybrid discrete event/agent-based simulation model to replicate a serious bacterial outbreak of resistant Escherichia coli in a large metropolitan public hospital during 2017. We tested the 3 strategies of using whole-genome sequencing early, late (actual outbreak), or not using it and assessed their associated outbreak size and hospital cost. The model included ward dynamics, pathogen transmission, and associated hospital costs during a 5-month outbreak. Model parameters were determined using data from the Queensland Hospital Admitted Patient Data Collection (N = 4809 patient admissions) and local clinical knowledge. Sensitivity analyses were performed to address model and parameter uncertainty.

RESULTS

An estimated 197 patients were colonized during the outbreak, with 75 patients detected. The total outbreak cost was A$460 137 (US$317 117), with 6.1% spent on sequencing. Without sequencing, the outbreak was estimated to result in 352 colonized patients, costing A$766 921 (US$528 547). With earlier detection from use of routine sequencing, the estimated outbreak size was 3 patients and cost A$65 374 (US$45 054).

CONCLUSIONS

Using whole-genome sequencing in hospital outbreak management was associated with smaller outbreaks and cost savings, with sequencing costs as a small fraction of total hospital costs, supporting the further investigation of the use of routine whole-genome sequencing in hospitals.

Emergence of diversity in carbapenemase-producing Escherichia coli ST131, England, January 2014 to June 2016

Background

Escherichia coli ST131, a global, high-risk clone, comprises fluoroquinolone resistance (FQ-R) mutations and CTX-M extended-spectrum beta-lactamases associated with the fimH30-encoding clades, C1 and C2. Further carbapenem resistance development in ST131 is a public health concern.

Aim

This observational study aimed to probe the diversity of carbapenemase-producing E. coli (CP E. coli) ST131 across England.

Methods

ST131 isolates were identified using whole-genome sequencing (WGS) data generated for all non-duplicate CP E. coli from human samples submitted to the national reference laboratory from January 2014 to June 2016. Antimicrobial resistance (AMR) gene content and single nucleotide polymorphism (SNP) data were compared against a published ST131 phylogeny and analysed alongside patient metadata.

Results

Thirty-nine genetically diverse ST131 CP E. coli, from eight of nine regions, represented 10% of CP E. coli isolates sequenced. Ten and eight isolates were from the FQ-susceptible (FQ-S) clades A and B, while eight and 15 isolates belonged to the FQ-R clades C1 or C2, respectively. Seven distinct carbapenemases were identified: KPC-2 (21 isolates, 6 regions) frequently occurred among clade C2 isolates (n = 10). OXA-48-producers (10 isolates, 3 regions) were often from clade A (n = 5). NDM-1 (n = 4), NDM-5 (n = 1), VIM-1 (n = 1), VIM-4 (n = 1) and OXA-181 (n = 1) were also identified. Clade C2 isolates encoded more AMR genes than those from clades A (p = 0.02), B (p = 9.6 x 10⁻³) or C1 (p = 0.03).

Conclusion

When compared with its global predominance among ESBL-E. coli, ST131 represented a fraction of the CP E. coli received, belonging to diverse clades and encoding diverse carbapenemases. The greater accumulation of resistance genes in clade C2 isolates highlights the need for ongoing monitoring of this high-risk lineage.

Molecular Mechanisms, Epidemiology, and Clinical Importance of β-Lactam Resistance in Enterobacteriaceae

Despite being members of gut microbiota, Enterobacteriaceae are associated with many severe infections such as bloodstream infections. The β-lactam drugs have been the cornerstone of antibiotic therapy for such infections. However, the overuse of these antibiotics has contributed to select β-lactam-resistant Enterobacteriaceae isolates, so that β-lactam resistance is nowadays a major concern worldwide. The production of enzymes that inactivate β-lactams, mainly extended-spectrum β-lactamases and carbapenemases, can confer multidrug resistance patterns that seriously compromise therapeutic options. Further, β-lactam resistance may result in increases in the drug toxicity, mortality, and healthcare costs associated with Enterobacteriaceae infections. Here, we summarize the updated evidence about the molecular mechanisms and epidemiology of β-lactamase-mediated β-lactam resistance in Enterobacteriaceae, and their potential impact on clinical outcomes of β-lactam-resistant Enterobacteriaceae infections.

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.

Double-carbapenem therapy in the treatment of multidrug resistant Gram-negative bacterial infections: a systematic review and meta-analysis

BACKGROUND

To compare the efficacy and safety of double-carbapenem therapy (DCT) with other antibiotics for the treatment of multidrug resistant (MDR) Gram-negative bacterial infections.

METHODS

Cochrane Library, PubMed, Embase and Web of Science as well as Chinese databases were searched from database establishment to February 2019. All types of studies were included if they had evaluated efficacy and safety of DCT regimens in patients with MDR Gram-negative bacterial infections. Clinical response, microbiological response, adverse events and mortality were the main outcomes. The protocol was registered with PROSPERO No. CRD42019129979.

RESULTS

Three cohort or case-control studies consisting of 235 patients and 18 case series or case reports consisting of 90 patients were included. The clinical and microbiological responses were similar between DCT and other regimens in patients with carbapenem-resistant Enterobacteriaceae (CRE) infection. DCT achieved a lower mortality than comparators in patients with CRE infection (OR = 0.44, 95% CI = 0.24-0.82, P = 0.009). Ertapenem was the most reported antibiotic in DCT regimens in case series or case reports. Moreover, clinical and microbiological improvements were found in 59 (65.6%) and 63 (70%) in total 90 cases, respectively.

CONCLUSIONS

DCT was as effective as other antibiotics in treating MDR Gram-negative bacterial infections, with similar efficacy response and lower mortality. DCT could be an alternative therapeutic option in the treatment of MDR Gram-negative bacterial infections. High-quality randomized controlled trials were required to confirm the beneficial effects of DCT.

Prevalence and Molecular Characterization of Extended Spectrum β-Lactamase, Plasmid-Mediated Quinolone Resistance, and Carbapenemase-Producing Gram-Negative Bacilli in Burkina Faso

The spreading of carbapenemase-producing gram-negative bacilli (GNB) must be considered as an "urgent" threat. The aim of this study was to determine the prevalence of extended spectrum β-lactamase (ESBL), plasmid-mediated quinolone resistance (PMQR), and carbapenemase-producing GNB and to characterize the supporting genes in GNB specimens isolated from patients and healthy volunteers in Burkina Faso. From April to June 2016, carbapenemase-producing GNB screening was performed in 1,230 consecutive clinical specimens, and 158 fecal samples from inpatients and healthy volunteers without digestive pathology at Souro Sanou University Hospital, Bobo Dioulasso. Strains were identified by matrix-assisted laser desorption ionization-time of flight and antimicrobial susceptibility was tested with the disk diffusion method on Müller-Hinton agar. The presence of carbapenemase, ESBL, and PMQR genes was assessed by multiplex PCR. The molecular epidemiological study was performed using multilocus sequence typing analysis. From the 1,230 clinical samples, 443 GNB strains were isolated among which 4 (0.9%) were carbapenemase-producing isolates (Escherichia coli, n = 1; Acinetobacter baumannii, n = 3). Among the 158 fecal samples tested for carbapenemase-producing Enterobacteriaceae carriage, 13 (8.2%) were carbapenemase-producing isolates (E. coli, n = 4; Klebsiella pneumoniae, n = 6; A. baumannii, n = 2; Acinetobacter nosocomialis, n = 1; Acinetobacter bereziniae, n = 1). The strains from the two groups were resistant to broad-spectrum cephalosporins (100% for both), gentamicin (100% and 64.3%), levofloxacin (100% and 85.7%), and to amikacin (0% and 7.1%). The carbapenemase-encoding genes bla_NDM-1, bla_Oxa-58, bla_Oxa-181, and bla_VIM-2 were detected in clinical and in fecal samples. The majority (10/11) of the enterobacterial strains carried also bla_CTX-M-15. The majority of the strains belonged to ST692 for E. coli, to ST147 for K. pneumoniae and to ST2 for A. baumannii. This study confirms the presence of carbapenemase-producing GNB in samples from patients and healthy volunteers. More effective active surveillance activities are needed.

Prevalence and Characteristics of Carbapenemase-Producing Enterobacteriaceae in Three Tertiary-Care Korean University Hospitals between 2017 and 2018

The aim of this study was to evaluate the prevalence and characteristics of carbapenemase-producing Enterobacteriaceae (CPE) from 3 tertiary-care Korean university hospitals between 2017 and 2018. Non-duplicated clinical isolates of Enterobacteriaceae showing resistance to any carbapenem agents were collected prospectively from 3 tertiary university hospitals between 2017 and 2018. The presence of carbapenemase genes was detected by multiplex PCR and sequencing for bla_KPC, bla_VIM, bla_NDM, bla_IMP, bla_OXA, and bla_GES was performed. Among the 690 potential carbapenem-resistant Enterobacteriaceae (CRE) isolates, 66.8% (N = 461) were CPE. The species distribution of CPE was as follows: Klebsiella pneumoniae was most common (75.9%), followed by Escherichia coli (15.0%), Citrobacter freundii (4.6%), Enterobacter cloacae (2.6%), Klebsiella. aerogenes (0.7%), and Klebsiella. oxytoca (0.4%). All 11 CPE genes were detected, particularly K. pneumoniae carbapenemase (KPC)-2 (87.6%), New Delhi metallo-β-lactamase (NDM)-1 (7.4%), NDM-5 (1.7%), KPC-3 (1.3%), oxacillinase (OXA)-232 (1.1%), and OXA-181 (1.1%). Six isolates produced 2 or 3 carbapenemases. The majority of the carbapenemase-producing C. freundii tested positive for NDM-1. We confirmed a high proportion of CPE among the CRE isolates with a high prevalence of KCP-2-producing K. pneumoniae and E. coli. Therefore, there is a need for undertaking continuous surveillance to monitor the prevalence of CPE.

Epidemiology and control measures of an OXA-48-producing Enterobacteriaceae hospital outbreak

Carbapenemase-producing Enterobacteriaceae (CPE) are a significant challenge to healthcare and infection prevention and control teams. In the UK, OXA-48-like carbapenemases are frequently reported. We describe an outbreak of OXA-48-like producing Enterobacteriaceae and the control measures that proved effective in containing further spread.

Aim

To describe epidemiologic and laboratory features of outbreak and highlight key control interventions.

Findings

Following the introduction of an increased sensitivity CPE screening protocol, OXA-48-like CPE were identified in screening and clinical samples from 96 patients across five hospital wards between November 2017 and July 2018. Klebsiella pneumoniae and Enterobacter cloacae were the most frequently isolated organisms, although a range of OXA-48-like positive organisms were identified. The outbreak was contained utilising certain key interventions, including the modification of laboratory screening processes, engagement of hospital senior management, clear and frequent communication and a strong ‘ward presence’ by the infection prevention and control team (IPCT).

Conclusion

Our report describes how a change in laboratory CPE screening process unmasked a CPE outbreak. The range of bacterial species harbouring the OXA-48-like mechanism suggested plasmid-mediated transfer of resistance. The timely implementation of interventions using a clinical, ‘ward-based’ approach to infection prevention and control highlights the importance of behavioural change in infection control interventions and enabled the termination of a large outbreak without recourse to environmental sampling, major remedial construction work or extensive molecular strain or plasmid typing.

One-Step Differential Detection of OXA-48-Like Variants Using High-Resolution Melting (HRM) Analysis

OXA-48-like carbapenemase gene remains a hidden threat, as different OXA-48 variants have varying presentations of susceptibility to antibiotics that might affect the treatment decisions. Rapid detection and differentiation of OXA-48-like carbapenemase genes are critical for targeted treatment and infection control. In this study, we aimed to develop high-resolution melting (HRM) analysis for the differentiation of OXA-48 variants. HRM analysis is a post-polymerase chain reaction (post-PCR) method for identification of small variations in nucleic acid sequences based on the PCR dissociation curve. A total of 82 bacterial strains, which consisted of Enterobacteriaceae and non-Enterobacteriaceae, were collected from a tertiary teaching hospital. The sensitivity and specificity of the assay were determined, and the developed assay was evaluated using the collected isolates against conventional-sequencing method. Overall, the developed assay was able to detect isolates that harboured OXA-48 and OXA232/OXA-181 by showing two distinct peaks at 81.1 ± 0.2 °C and 82.1 ± 0.2 °C, respectively. The detection limit of the assay was 1.6 x 10⁻⁶ ng/µL for OXA-48 and 1.8 × 10⁻⁷ ng/µL for OXA-232/OXA-181. This assay showed 100% specificity when evaluated on a panel of 37 isolates comprised of different species of bacteria and yeasts. When the assay with isolates collected in the year 2016 was first evaluated, the assay showed comparable results with conventional PCR-sequencing method where 34 OXA-48 and OXA-232/OXA-181 were detected. By using HRM analysis, the presence of OXA-48-like variants could be easily identified within 3 h from the pure culture.

Evaluation of the MBT STAR-Carba Assay for the Detection of Carbapenemase Production in Enterobacteriaceae and Hafniaceae with a Large Collection of Routine Isolates from Plate Cultures and Patient-Derived Positive Blood Cultures

The spread of carbapenemase-producing Enterobacterales is a major public health concern worldwide, and methods for their prompt and reliable detection are highly demanded for therapeutic and hygiene control purposes. In this study, we evaluate the MBT STAR^®-Carba assay (Bruker Daltonik) to detect the carbapenemase production in clinical and surveillance isolates from plate cultures and directly from patient-derived positive blood cultures bottles. Overall, n = 1,307 samples were analyzed (n = 900 plate cultures, and n = 407 positive blood cultures, using the bacterial pellet obtained with the Sepsityper^® Kit; Bruker Daltonik), including n = 793 carbapenemase producers (n = 579 Klebsiella pneumoniae carbapenemase, n = 161 metallo-beta-lactamases, n = 45 OXA-48, and eight isolates harboring two different enzymes), n = 239 carbapenem-resistant noncarbapenemase producers, and n = 275 carbapenem-susceptible strains. The STAR-Carba assay detected 657/661 (99.4%) carbapenemase producers from plate cultures, and 132/132 (100%) from positive blood cultures. Specificity resulted in 100% for carbapenem-susceptible strains, and 91.6% for carbapenem-resistant strains resulted negative for carbapenamase production with the routine methods used in this study. In this study, the MBT STAR-Carba assay proved to be a highly reliable method for the detection of carbapenemase-producing Enterobacterales, regardless of the enzyme family, and from both plate cultures and positive blood culture bottles.

Substrate Specificity of OXA-48 after β5-β6 Loop Replacement

OXA-48 carbapenemase has rapidly spread in many countries worldwide with several OXA-48-variants being described, differing by a few amino acid (AA) substitutions or deletions, mostly in the β5-β6 loop. While single AA substitutions have only a minor impact on OXA-48 hydrolytic profiles, others with 4 AA deletions result in loss of carbapenem hydrolysis and gain of expanded-spectrum cephalosporin (ESC) hydrolysis. We have replaced the β5-β6 loop of OXA-48 with that of OXA-18, a clavulanic-acid inhibited oxacillinase capable of hydrolyzing ESCs but not carbapenems. The hybrid enzyme OXA-48Loop18 was able to hydrolyze ESCs and carbapenems (although with a lower k_cat), even though the β5-β6 loop was longer and its sequence quite different from that of OXA-48. The kinetic parameters of OXA-48Loop18 were in agreement with the MIC values. X-ray crystallography and molecular modeling suggest that the conformation of the grafted loop allows the binding of bulkier substrates, unlike that of the native loop, expanding the hydrolytic profile. This seems to be due not only to differences in AA sequence, but also to the backbone conformation the loop can adopt. Finally, our results provide further experimental evidence for the role of the β5-β6 loop in substrate selectivity of OXA-48-like enzymes and additional details on the structure-function relationship of β-lactamases, demonstrating how localized changes in these proteins can alter or expand their function, highlighting their plasticity.

Lateral flow immunochromatographic assay for rapid screening of faecal carriage of carbapenemase-producing Enterobacteriaceae

Background

Rapid and effective screening of carbapenemase-producing Enterobacteriaceae (CPE) appears essential for adequate patient management and rapid implementation of infection control measures. Most of these screening techniques require a minimum of 24 h of culture. Molecular assays are an exception since these can be achieved within 1 h, but are expensive and usually require specialized facilities and trained personnel. In this context, lateral immunochromatography performed directly from rectal swab samples could represent a cost-effective alternative with a reduced turnaround time.

Objectives

In this study, we assessed the performance of the OKN K-SeT test (Coris BioConcept, Gembloux, Belgium) for the rapid detection of OXA-48, KPC and NDM CPE directly from rectal swab samples.

Methods

A total of 149 residual rectal swabs, routinely screened for CPE through selective culture and confirmed by PCR, were tested with a defined protocol consisting of a 2.5 h incubation of the swab in an enrichment medium containing meropenem followed by OKN K-SeT testing after centrifugation.

Results

This method displayed an overall sensitivity of 96% and a specificity of 100% with a limit of detection ranging between 104 and 105 cfu/mL.

Conclusions

Whereas this assay appears highly specific, it displays a reduced sensitivity compared with the standard procedure encompassing a culture step. Nonetheless, this rapid method allows an accelerated identification of most CPE carriers at a lower cost and, accordingly, the implementation of early appropriate management procedures.

Whole-genome sequencing and comparative genomic analysis of Shewanella xiamenensis strains carrying blaOXA-48-like genes isolated from a water environment in Vietnam

OBJECTIVES

The aim of this study was to understand the natural bacterial hosts of antimicrobial resistance genes (ARGs) and their impact on the processes of evolution, spread and positive selection of acquired ARGs.

METHODS

Environmental carbapenem-resistant Gram-negative bacteria in Vietnam were screened for based on a One Health approach. Whole-genome sequencing (WGS) and comparative genomic analysis of the isolates were performed. WGS of three carbapenem-resistant Shewanella xiamenensis strains (SxND_W2_2018, SxND_W5_2018 and SxND_W9_2018) isolated from canals in Truc Ninh District and Nghia Hung District, Nam Dinh Province, Vietnam, in 2018 was performed using an Illumina MiniSeq system. ARGs in the draft genome sequences were detected using ResFinder, and comparison of genomic regions was performed using BLASTn and Easyfig.

RESULTS

Thebla_OXA-48-like carbapenem-hydrolysing class D β-lactamase genes bla_OXA-48, bla_OXA-252 and bla_OXA-547 were detected in chromosomal contigs of SxND_W2_2018, SxND_W5_2018 and SxND_W9_2018, respectively. Comparative analysis of the surrounding regions of the bla_OXA-48-like genes, including both 10 kb upstream and 10 kb downstream of the genes, showed that the genomic regions were highly conserved in all three isolates.

CONCLUSION

This study analysed the draft genome sequences of carbapenem-resistantS. xiamenensis strains isolated from a water environment in Vietnam. All of the strains carried bla_OXA-48-like gene variants in their chromosomes. This information will contribute to highlight the evolution of bla_OXA-48 family carbapenemase genes in nature and the importance of S. xiamenensis as a natural reservoir of important ARGs in the environment in Vietnam.

Pharmacological Interventions for Bacterial Prostatitis

Prostatitis is a common urinary tract condition but bring innumerable trouble to clinicians in treatment, as well as great financial burden to patients and the society. Bacterial prostatitis (acute bacterial prostatitis plus chronic bacterial prostatitis) accounting for approximately 20% among all prostatitis have made the urological clinics complain about the genital and urinary systems all over the world. The international challenges of antibacterial treatment (emergence of multidrug-resistant bacteria, extended-spectrum beta-lactamase-producing bacteria, bacterial biofilms production and the shift in bacterial etiology) and the transformation of therapeutic strategy for classic therapy have attracted worldwide attention. To the best of our knowledge currently, there is not a single comprehensive review, which can completely elaborate these important topics and the corresponding treatment strategy in an effective way. This review summarizes the general treatment choices for bacterial prostatitis also provides the alternative pharmacological therapies for those patients resistant or intolerant to general treatment.

Resistance to carbapenems and other antibiotics in Klebsiella pneumoniae found in seals indicates anthropogenic pollution

BACKGROUND

The beta-lactamase enzyme OXA-48 has spread widely in recent years in Enterobacteriaceae associated with man, disseminated primarily on incompatibility group L/M plasmids. OXA-48 confers resistance to carbapenems, important antimicrobials for treating highly resistant bacterial infections in humans. This enzyme has rarely been detected in bacteria from animals. Furthermore, the use of carbapenem compounds is not permitted in food-producing animals in Europe and to our knowledge has not been reported in food-producing animals globally.

METHODS

Bacterial isolates from lesions in stranded, free-living, juvenile common seals (Phoca vitulina) were identified. Antimicrobial susceptibility testing and whole genome sequencing analysis were used to characterise antimicrobial resistance genes carried by the bacteria.

RESULTS

Here, we report the detection of Klebsiella pneumoniae subspecies pneumoniae carrying the bla _OXA-48 gene on an incompatibility group L/M plasmid from an infection in a common seal.

CONCLUSION

Evidence is accruing that marine mammals may be infected with bacteria originating from anthropogenic sources, such as human sewage, contaminating the environment.

Unorthodox Parenteral β-Lactam and β-Lactamase Inhibitor Combinations: Flouting Antimicrobial Stewardship and Compromising Patient Care

In India and China, indigenous drug manufacturers market arbitrarily combined parenteral β-lactam and β-lactamase inhibitors (BL-BLIs). In these fixed-dose combinations, sulbactam or tazobactam is indiscriminately combined with parenteral cephalosporins, with BLI doses kept in ratios similar to those for the approved BL-BLIs. Such combinations have been introduced into clinical practice without mandatory drug development studies involving pharmacokinetic/pharmacodynamic, safety, and efficacy assessments being undertaken. Such unorthodox combinations compromise clinical outcomes and also potentially contribute to resistance development.

Role of Arginine 214 in the Substrate Specificity of OXA-48

Increasing numbers of variants of the carbapenem-hydrolyzing class D β-lactamase OXA-48 are identified in Enterobacterales worldwide. Among them, OXA-181 and OXA-232 are of particular interest, as they differ from each other by a single amino acid substitution at position 214 (R in OXA-181 and S in OXA-232) that results in reduced carbapenem-hydrolyzing activity for OXA-232. To investigate the role of amino acid position 214 (AA214), the X-ray structure of OXA-232 was determined and AA214 of OXA-48 and of OXA-232 was replaced by G, L, D, E, S, R, and K using site-directed mutagenesis. These mutants were phenotypically characterized, and three mutants of OXA-232 were purified to study their steady-state kinetic properties. The X-ray structure of OXA-232 along with molecular modeling studies showed that the interaction via a salt bridge between R214 and D159 in OXA-48 is not possible with the G214 or S214 mutation. In contrast, with K214, which is also positively charged, the interaction with D159 is maintained. With the E214 mutant, an alternative binding conformation of imipenem that is not compatible with a nucleophilic attack by S70 was evidenced. Thus, imipenem has a very poor apparent affinity for the E214 mutant because of its nonproductive binding mode. Similarly, we could explain the lack of temocillin hydrolysis by the OXA-232-S214E mutant, which is due to the unfavorable interaction between the negatively charged R1 substituent of temocillin with the E214 residue. Overall, we demonstrate that AA214 in OXA-48-like β-lactamases is critical for the carbapenemase activity.

The Current Burden of Carbapenemases: Review of Significant Properties and Dissemination among Gram-Negative Bacteria

Carbapenemases are β-lactamases belonging to different Ambler classes (A, B, D) and can be encoded by both chromosomal and plasmid-mediated genes. These enzymes represent the most potent β-lactamases, which hydrolyze a broad variety of β-lactams, including carbapenems, cephalosporins, penicillin, and aztreonam. The major issues associated with carbapenemase production are clinical due to compromising the activity of the last resort antibiotics used for treating serious infections, and epidemiological due to their dissemination into various bacteria across almost all geographic regions. Carbapenemase-producing Enterobacteriaceae have received more attention upon their first report in the early 1990s. Currently, there is increased awareness of the impact of nonfermenting bacteria, such as Acinetobacter baumannii and Pseudomonas aeruginosa, as well as other Gram-negative bacteria that are carbapenemase-producers. Outside the scope of clinical importance, carbapenemases are also detected in bacteria from environmental and zoonotic niches, which raises greater concerns over their prevalence, and the need for public health measures to control consequences of their propagation. The aims of the current review are to define and categorize the different families of carbapenemases, and to overview the main lines of their spread across different bacterial groups.

Prevalence and clonal relatedness of NDM and OXA-48-producing Klebsiella pneumoniae in a tertiary care hospital in South India

BACKGROUND

Carbapenems are used for the treatment of serious infections caused by multidrug-resistant Klebsiella pneumoniae. Resistance to carbapenems in K. pneumoniae is mainly due to metallo-beta-lactamases (NDM, IMP, and VIM) and class D oxacillinase (OXA-48-like).

AIM AND OBJECTIVE

This study was undertaken to detect the genes encoding for carbapenemase in K. pneumoniae and to determine the clonal relatedness of selected isolates of K. pneumoniae producing NDM and OXA-48 by pulsed-field gel electrophoresis method (PFGE).

MATERIALS AND METHODS

The isolates were collected over a period of 1 year. A total of 370 clinically significant, nonduplicate isolates of K. pneumoniae were included in this study. Phenotypic tests for the detection of carbapenemases were performed for all the isolates. Polymerase chain reaction (PCR) was carried out for the detection of carbapenemase genes such as bla _KPC, bla _IMP, bla _VIM, bla _NDM, and bla _OXA-48. PFGE was performed, and the PFGE profiles were analyzed and compared using BioNumerics version 7.6.

RESULTS

Of the 370 isolates of K. pneumoniae, carbapenemase genes were detected in 13.78% (51/370). bla _OXA-48 was the prevalent gene detected followed by bla _NDM and bla _KPC. Thirty strains of K. pneumoniae selected by PFGE analysis were divided into five clusters (A, B, C, D, and E). Cluster C was the major type detected carrying bla _NDM and bla _OXA-48 genes.

CONCLUSION

bla _OXA-48 was the most prevalent gene detected in this study. PCR is useful in detecting carbapenemase genes, especially bla _NDM, which may show false susceptibility to carbapenems. There was no direct correlation detected between PFGE profiles and antibiotic susceptibility pattern. PFGE has revealed the genomic diversity among isolates, thereby suggesting heterogeneity in strain circulation within intensive care unit and wards of the hospital. Monitoring and molecular typing is essential to curtail the spread of multidrug-resistant strains and control the outbreaks of infection.

High Carriage Rates of Multidrug-Resistant Gram-Negative Bacteria in Neonatal Intensive Care Units From Ghana

Background

Carriage of multidrug resistant (MDR) Gram-negative bacteria (GN) in hospitalized neonates may increase the risk of difficult-to-treat invasive infections at neonatal intensive care units (NICUs). Data on MDRGN carriage among hospitalized newborns in Africa are limited.

Methods

We conducted a cross-sectional study at the NICUs of 2 tertiary hospitals in Ghana. Swabs from the axilla, groin, perianal region, and the environment were cultured, GN were identified, and antibiotic susceptibility was tested. We obtained blood culture isolates from neonates with sepsis. Whole-genome sequencing was used to characterize carbapenemase-producing Klebsiella pneumoniae. Typing was done by multilocus sequence typing (MLST) and single nucleotide polymorphism (SNP) analysis.

Results

A total of 276 GN were isolated from 228 screened neonates. Pathogenic GN were cultured in 76.8% (175 of 228) of neonates. Klebsiella spp (41.7%; 115 of 276) and Escherichia coli (26.4%; 73 of 276) were the commonest organisms. Carriage rates of MDRGN and third-generation cephalosporin resistant organisms were 49.6% (113 of 228) and 46.1% (105 of 228), respectively. Among Klebsiella spp, 75.6% (87 of 115) phenotypically expressed extended-spectrum β-lactamase activity, whereas 15.6% expressed carbapenemase and harbored bla-_OXA-181 and bla-_CTX-M-15. Overall, 7.0% (16 of 228) of neonates developed GN bloodstream infection. In 2 of 11 neonates, sequencing showed the same identity between carriage and the bloodstream isolate. Length of stay before specimen collection and antibiotic use were independently associated with carriage rates, which increased from 13% at admission to 42% by day 2 and reached a plateau at 91% by day 15.

Conclusions

High carriage rates of MDRGN, including carbapenemase-producing enterobacterales may be an emerging problem in NICUs in Africa.

Characterization of Carbapenemase-Producing Klebsiella pneumoniae in Clinical Center University of Sarajevo, Bosnia and Herzegovina

Klebsiella pneumoniae is the second most prevalent gram-negative rod that causes nosocomial infections in hospitalized or otherwise immunocompromised patients. It can develop multiple drug resistance that results in limited treatment options and increased use of carbapenems. Various mechanisms are related to the development of carbapenem resistance in K. pneumoniae. The aim of this study was to perform phenotypic and molecular characterization of clinical isolates of carbapenemase-producing K. pneumoniae from two outbreaks recorded in 2017 and 2018 in Clinical Center University of Sarajevo, Bosnia and Herzegovina. Identification of K. pneumoniae isolates was carried out on the basis of morphological, cultural, and biochemical characteristics. Interpretation of antimicrobial resistance was performed according to EUCAST breakpoints. There were four different resistotypes of carbapenemase-producing K. pneumoniae in this study and all were confirmed positive for bla_OXA-48 carbapenemase. Rep-PCR fingerprinting of these strains showed the presence of the two different genetic patterns with no similarity between them. The monitoring, surveillance, and molecular typing are essential to control the emergence of multidrug-resistant strains in nosocomial settings, and to reduce the frequency of outbreak occurrence.

Spread of OXA-48 and NDM-1-Producing Klebsiella pneumoniae ST48 and ST101 in Chicken Meat in Western Algeria

Aim: We investigated the prevalence of carbapenemase-producing Enterobacteriaceae (CPE) in chicken meat in Western Algeria in 2017. Results: From February to July 2017, samples of chicken meat from three poultry farms in Western Algeria were screened for the presence of CPE. Strains were characterized with regard to antibiotic resistance, β-lactamase content, Plasmid-mediated quinolone resistance, sulfonamide resistance genes, clonality (repetitive sequence-based profiles and multilocus sequence typing) and virulence traits. Of 181 samples analyzed, 29 (16.0%) carbapenemase-producing Klebsiella pneumoniae were detected. Twenty-three OXA-48-producers (79.3%) and six (20.7%) New Delhi metallo (NDM)-1-producers were observed. Clonality analysis showed three distinct lineages and clonal expansions of the OXA-48-producing K. pneumoniae ST48 and the NDM-1-producing K. pneumoniae ST101. These isolates harbored fimH, ureA, mrkD, entB, uge, and wabG. Neither capsular serotype genes nor hypermucoviscous phenotype were detected. Plasmid analysis confirmed that all these isolates harbored the transferable IncL and IncFIIK plasmids. Conclusions: This study reports the spread of OXA-48 and NDM-1-producing K. pneumoniae ST48 and ST101 in chicken meat in Western Algeria and demonstrates that food represents a reservoir of the carbapenemases encoding genes.

OXA-48 Carbapenemase in Klebsiella pneumoniae Sequence Type 307 in Ecuador

Antibiotic resistance is on the rise, leading to an increase in morbidity and mortality due to infectious diseases. Klebsiella pneumoniae is a Gram-negative bacterium that causes bronchopneumonia, abscesses, urinary tract infection, osteomyelitis, and a wide variety of infections. The ubiquity of this microorganism confounds with the great increase in antibiotic resistance and have bred great concern worldwide. K. pneumoniae sequence type (ST) 307 is a widespread emerging clone associated with hospital-acquired infections, although sporadic community infections have also been reported. The aim of our study is to describe the first case of Klebsiella pneumoniae (ST) 307 harboring the blaOXA-48-like gene in Ecuador. We characterized a new plasmid that carry OXA-48 and could be the source of future outbreaks. The strain was recovered from a patient with cancer previously admitted in a Ukrainian hospital, suggesting that this mechanism of resistance could be imported. These findings highlight the importance of programs based on active molecular surveillance for the intercontinental spread of multidrug-resistant microorganisms with emergent carbapenemases.

Development of a MALDI-TOF MS-based screening panel for accelerated differential detection of carbapenemases in Enterobacterales using the direct-on-target microdroplet growth assay

Carbapenemase-producing bacteria are a growing issue worldwide. Most phenotypic detection methods are culture-based, requiring long incubation times. We present a phenotypic screening panel for detection of carbapenem non-susceptibility and differentiation of carbapenemase classes and AmpC, the MALDI-TOF MS-based direct-on-target microdroplet growth assay (DOT-MGA). It was validated on 7 reference strains and 20 challenge Enterobacterales isolates. Broth microdilution (BMD) and combination disk test (CDT) were also performed, as well as PCR as reference method. The panel based on the synergy between meropenem and carbapenemase inhibitors, determined by incubating these substances with bacterial suspension on a MALDI-TOF MS target and subsequently assessing bacterial growth on the target's spots by MS. After 4 hours of incubation, DOT-MGA correctly identified KPC, MBL and OXA (100% agreement with PCR). Detection of AmpC coincided with BMD and CDT but agreement with PCR was low, not ruling out false negative PCR results. DOT-MGA delivered more accurate results than BMD and CDT in a significantly shorter time, allowing for detection of carbapenem non-susceptibility, MIC determination and carbapenemase differentiation in one step.

Ceftazidime/Avibactam, Meropenem/Vaborbactam, or Both? Clinical and Formulary Considerations

Ceftazidime/avibactam and meropenem/vaborbactam are changing the management of invasive infections due to carbapenem-resistant Enterobacteriaceae (CRE), leading to higher rates of clinical cure, decreased mortality, and decreased rates of acute kidney injury compared with colistin-based regimens. However, these 2 agents are not interchangeable with regard to management of CRE infections, and clinicians need to be aware of their differences. This review focuses on differences in the in vitro activity of these agents as a function of mechanism of carbapenem resistance, the clinical data supporting their superiority over colistin-based therapy, and the differences between agents with regard to propensity for selection of resistance. Furthermore, considerations and recommendations for hospital formularies and antibiotic stewardship programs regarding positioning of these agents are discussed.

Diagnostic performance of the Xpert Carba-R™ assay directly from rectal swabs for active surveillance of carbapenemase-producing organisms in the largest Brazilian University Hospital

BACKGROUND

The global spread of carbapenemase-producing organisms (CPO) has been considered by international health authorities as a critical public health concern. Brazil has a high CPO prevalence according to distinct publications but many routine microbiology laboratories have only phenotypic resources to evaluate this epidemiological situation, which is time-consuming and detects only carbapenem-resistant isolates missing CPO susceptible expressing a slightly decreased susceptibility. New molecular platforms can detect CPO faster but a local evaluation is essential.

AIM

To evaluate the performance of CPO detection direct from rectal swabs with the Xpert Carba-R™ assay (Cepheid, Sunnyvale, CA) in the largest Brazilian University Hospital.

METHODS

A prospective diagnostic accuracy study of CPO was performed with the collection of rectal swabs from patients admitted into the Intensive Care Unit (ICU) and into the Emergency Department (ED) between April and July 2016. The Xpert Carba-R™ assay results were compared with carbapenem-resistant Enterobacterales (CRE) surveillance cultures plus in-house PCR carbapenemase detection (reference method). In case of discordant results between methods, additional tests were performed. The limit of detection (LoD) for the CRE culture and the Xpert Carba-R™ assay were performed with contrived isolates of known carbapenemases genes.

RESULTS

A total of 921 clinical rectal swabs were analyzed being 21% (196/921) from the ICU and 79% (725/921) from the ED. Overall, the Xpert Carba-R™ assay detected 9.9% (91/921) of CPOs being 9.5% (87/921) positive only for bla_KPC and 0.4% (4/921) positive only for bla_NDM. The reference method detected 9.1% (84/921) CPO being 77 (8.4%) bla_KPC, 5 bla_VIM (0.5%) and 2 bla_NDM (0.2%). No IMP or OXA-48 like gene was detected. Overall, twelve samples, 1.3% (10 bla_KPC, 2 bla_NDM) were Xpert Carba-R™ positive but negative by the reference method. Five isolates (0.5%) were positive for bla_VIM only by in-house PCR and confirmed to be bla_VIM-2 by DNA sequencing. The Kappa value, sensitivity, specificity, positive/negative predictive values and accuracy of the Xpert Carba-R™ assay were; 0.893 (95% confidence interval [CI], 0.842-0.944), 94% (86.7-98.0), 98.6% (97.5-99.3), 86.8% (78.1-93.0), 99.4% (98.6-99.8) and 98.2% (97.3-99.1), respectively. The LoD for bla_KPC of the Xpert Carba-R™ assay and the CRE cultures were 10¹ CFU/swab.

CONCLUSION

The Xpert Carba-R™ assay is an accurate test to detect CPO directly from the rectal swabs with significant lower turnaround time (TAT) when compared to the reference method (CRE culture plus in-house PCR). Xpert Carba-R™ may, therefore, be regarded as a good and fast epidemiological tool.

Detection of two simultaneous outbreaks of Klebsiella pneumoniae coproducing OXA-48 and NDM-1 carbapenemases in a tertiary-care hospital in Valencia, Spain

Klebsiella pneumoniae is one of the most common hospital-acquired Gram-negative pathogens. During the last decade, the emergence of strains with reduced susceptibility or resistance to carbapenems is becoming a therapeutic challenge. This study takes place after the isolation of 14 strains of carbapenem-resistant K. pneumoniae with similar susceptibility patterns and carriage of OXA-48 and NDM-1 carbapenemases genes. Fourteen patients were found to be colonized (faecal carriage) and/or infected by two different clones of carbapenemase-coproducing K. pneumoniae during a 1-year period of time. Some of the patients had shared a hospital ward and continued to be colonized several months after the outbreak.

Evaluation of Phenotypic and Genotypic Characteristics of Carbapnemases-producing Enterobacteriaceae and Its Prevalence in a Referral Hospital in Tehran City

Background & Objective

Carbapenem-resistant Enterobacteriaceae is a growing concern worldwide including Iran. The emergence of this pathogen is worrying as carbapenem is one of the 'last-line' antibiotics for treatment of infections caused by multi drug resistant gram- negative bacteria. The main objective of this study was to determine the prevalence of carbapenem-resistant Enterobacteriaceae in a referral hospital in Tehran, Iran.

Methods

In this study, all positive isolates of Enterobacteriaceae recorded in blood, urine, and other body fluids were studied during April 2017 to April 2018 in a referral hospital in Tehran. All cases of resistance to carbapenems were first tested by modified Hodge test. All cases with positive or negative test, after gene extraction, were examined genotypically based on the primers designed for the three Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-β-lactamase (NDM), and OXA-48 genes by conventional PCR method.

Results

108 isolates (13.6%) were resistant to all cephalosporins as well as to imipenem and meropenem. In a genotypic study, including 45 isolates, 13 isolates were positive for OXA-48 gene, 11 isolates for OXA-48 and NDM genes, 11 isolates for OXA-48, NDM and KPC genes, 4 isolates for OXA-48 genes and KPC, 3 isolates for NDM, one isolate for KPC. On the other hand, two isolates were negative for all three genes examined.

Conclusion

OXA-48 gene was one of the most common genes resistant to carbapenems in Iran. According to studies, the prevalence of antibiotic resistance in Iran is rising dramatically, which reduces the choice of antibiotics to treat severe infections in the future.

Epidemiology of β-Lactamase-Producing Pathogens

β-Lactam antibiotics have been widely used as therapeutic agents for the past 70 years, resulting in emergence of an abundance of β-lactam-inactivating β-lactamases. Although penicillinases in Staphylococcus aureus challenged the initial uses of penicillin, β-lactamases are most important in Gram-negative bacteria, particularly in enteric and nonfermentative pathogens, where collectively they confer resistance to all β-lactam-containing antibiotics. Critical β-lactamases are those enzymes whose genes are encoded on mobile elements that are transferable among species. Major β-lactamase families include plasmid-mediated extended-spectrum β-lactamases (ESBLs), AmpC cephalosporinases, and carbapenemases now appearing globally, with geographic preferences for specific variants. CTX-M enzymes include the most common ESBLs that are prevalent in all areas of the world. In contrast, KPC serine carbapenemases are present more frequently in the Americas, the Mediterranean countries, and China, whereas NDM metallo-β-lactamases are more prevalent in the Indian subcontinent and Eastern Europe. As selective pressure from β-lactam use continues, multiple β-lactamases per organism are increasingly common, including pathogens carrying three different carbapenemase genes. These organisms may be spread throughout health care facilities as well as in the community, warranting close attention to increased infection control measures and stewardship of the β-lactam-containing drugs in an effort to control selection of even more deleterious pathogens.

Evaluation of the performance of Acuitas® Resistome Test and the Acuitas Lighthouse® software for the detection of β-lactamase-producing microorganisms

OBJECTIVES

Given the international spread of multidrug-resistant Gram-negative bacteria the need for prompt and precise characterization of underlying resistance traits has evolved into the cornerstone of infection control strategies. Novel commercial molecular tests enable rapid simultaneous testing for multiple resistance genes. We aimed to evaluate the performance of OpGen's Acuitas® Resistome Test and the Acuitas Lighthouse® software.

METHODS

The test is tailored towards detecting 46 β-lactamase genes (SHV and TEM variants associated with wild-type penicillin resistance, extended-spectrum β-lactamases [ESBLs], acquired AmpCs and carbapenemases) via a microfluidic polymerase chain reaction (PCR) array. In total 118 isolates part of the collection of the Bacteriology Laboratory of the Hellenic Pasteur Institute, specifically 96 enterobacterial isolates and 21 Acinetobacter baumannii, of divergent origins, with previously characterized β-lactamase content, were tested.

RESULTS

In the enterobacterial group all 69 carbapenemase genes of the KPC, VIM, NDM and OXA-48 types were correctly identified (sensitivity, specificity, positive predictive value [PPV] and negative predictive value [NPV] of 100%). Non-ESBL SHV enzymes, ESBLs (CTX-M, GES, VEB types) and acquired AmpC enzymes were also correctly characterized. Of the 35 SHV-ESBLs harboured, correct identification was possible in 32/35 isolates, with overall sensitivity, specificity, PPV and NPV for the Klebsiella pneumoniae group of 89.29%, 100%, 100% and 91.18%, respectively. For the A. baumannii group the test exhibited an overall sensitivity for carbapenemase detection of 96.55% and 100% PPV.

CONCLUSIONS

The OpGen Acuitas Resistome Test is an efficient molecular tool that can identify resistance threats in health care institutions with high diagnostic accuracy and be integrated into targeted surveillance protocols.

Antimicrobial Resistance and Food Animals: Influence of Livestock Environment on the Emergence and Dissemination of Antimicrobial Resistance

The emergence and dissemination of antimicrobial resistance among human, animal and zoonotic pathogens pose an enormous threat to human health worldwide. The use of antibiotics in human and veterinary medicine, and especially the use of large quantities of antibiotics in livestock for the purpose of growth promotion of food animals is believed to be contributing to the modern trend of the emergence and spread of bacteria with antibiotic resistant traits. To better control the emergence and spread of antimicrobial resistance several countries from Western Europe implemented a ban for antibiotic use in livestock, specifically the use of antibiotics for growth promotion of food animals. This review article summarizes the recent knowledge of molecular acquisition of antimicrobial resistance and the effects of implementation of antibiotic growth promoter bans on the spread of antimicrobial resistant bacteria in animals and humans. In this article, we also discuss the main zoonotic transmission routes of antimicrobial resistance and novel approaches designed to prevent or slow down the emergence and spread of antimicrobial resistance worldwide. Finally, we provide future perspectives associated with the control and management of the emergence and spread of antimicrobial resistant bacteria.