Dynamics of blaOXA-23 gene transmission in Acinetobacter spp. from contaminated veterinary environmental surfaces: an emerging One Health threat?

BACKGROUND

Carbapenem-resistant Acinetobacter baumannii is a common pathogen associated with healthcare-acquired infections, and robust infection prevention and control protocols exist in human healthcare settings. In contrast, infection prevention and control (IPC) standards are limited in veterinary medicine, necessitating further investigation.

AIM

Examine the possible transmission of carbapenem-resistant Acinetobacter spp. in a veterinary practice where a cat was diagnosed with an OXA-23-producing A. baumannii ST2 strain.

METHODS

Environmental samples together with nasal and hand swabs from the veterinary personnel were collected. All swabs were screened for the presence of extended-spectrum-β-lactamase- and carbapenemase-producing Enterobacterales, meticillin-resistant staphylococcus and multi-drug-resistant Acinetobacter spp. Whole-genome sequencing was performed for carbapenemase-producing strains.

RESULTS

Of the veterinary staff, 60% carried meticillin-resistant Staphylococcus epidermidis. Environmental evaluation showed that 40% (N=6/15) of the surfaces analysed by contact plates and 40% (N=8/20) by swabs failed the hygiene criteria. Assessment of the surfaces revealed contamination with five OXA-23-producing Acinetobacter spp. strains: an OXA-23-producing Acinetobacter schindleri on the weight scale in the waiting room; and four OXA-23-producing Acinetobacter lwoffii strains, on different surfaces of the treatment room. The blaOXA-23 gene was located on the same plasmid-carrying Tn2008 across the different Acinetobacter spp. strains. These plasmids closely resemble a previously described OXA-23-encoding plasmid from a human Portuguese nosocomial Acinetobacter pittii isolate. Distinctly, the OXA-23-producing A. baumannii ST2 clinical strain had the resistant gene located on Tn2006, possibly inserted on the chromosome.

CONCLUSION

The detection of an OXA-23-producing A. baumannii ST2 veterinary clinical strain is of concern for companion animal health and infection, prevention and control. This study established the dynamic of transmission of the plasmid-mediated blaOXA-23 gene on critical surfaces of a small animal veterinary practice. The genetic resemblance to a plasmid found in human nosocomial settings suggests a potential One Health link.

Emergence of pandrug-resistant carbapenemase-producing Enterobacterales in dogs and cats: a cross-sectional study in Egypt

One of the most important emerging health problems is the increasing role of animals in the rapid global rise in resistance to last-resort antibiotics, such as carbapenems. However, there is limited information on the role of pet animals in harboring and spreading pandrug-resistant (PDR) carbapenemase-producing Enterobacterales (CPE), especially in Egypt. This cross-sectional study was conducted to screen for CPE in healthy and diseased pets using phenotypic and molecular methods and the NG-Test CARBA 5 immunochromatographic assay. Rectal swabs were collected from 62 dogs and 48 cats, incubated overnight in tryptic soy broth containing 10 μg of meropenem disc and subsequently cultured on MacConkey agar supplemented with meropenem (1 mg/L). Sixty-six isolates (60.6%), including 56 Klebsiella pneumoniae, seven Escherichia coli, and three K. oxytoca isolates, were confirmed to be carbapenem-resistant Enterobacterales (CRE) by the disc diffusion method, broth microdilution test, CNPt-direct, and PCR assay targeting carbapenemase genes. Forty-three (65.2%) dogs and 23 (34.8%) cats carried CPE. Of these, 35 (70.0%) were healthy (including 27 dogs and 8 cats) and 31 (52.5%) were diseased (including 16 dogs and 15 cats). bla OXA-181 was the most common gene detected (42/66, 63.6%), followed by bla IMP (40/66, 60.6%), bla OXA-48-like (29/66, 43.9%), bla KPC and bla VIM (20/66, 30.3% each), and bla NDM (17/66, 25.8%). The identified genotypes were bla KPC-2, bla IMP-1, bla VIM-1, bla NDM-1, and bla NDM-5. The CARBA 5 assay showed higher sensitivity and specificity for the detection of NDM, OXA and KPC than that for VIM and IMP genes. Antimicrobial resistance profiles of CRE isolates revealed 20 PDR, 30 extensively drug-resistant (XDR), and 16 multidrug-resistant (MDR) phenotypes. This study provides evidence of colonization with PDR CPE in dogs and cats. To manage the infection or colonization of pets in veterinary clinical settings, extended surveillance systems should be considered, and the use of critical antibiotics should be strictly controlled.

Multicenter study to assess the use of BL-DetecTool for the detection of CTX-M-type ESBLs and carbapenemases directly from clinical specimens

Antimicrobial resistance (AMR) is one of the major public health problems worldwide. Multiple strategies have been put in place to address this problem. One of them is the rapid detection of the mechanisms of resistance, such as extended-spectrum beta-lactamases (ESBLs) and/or carbapenemases. We conducted a multicenter study that included nine European centers for the assessment of prototypes of a novel lateral flow immunoassay-based device (BL-DetecTool) for a rapid detection of ESBL (NG-Test CTX-M-MULTI DetecTool) and/or carbapenemases (NG-Test CARBA 5 DetecTool) from Enterobacterales and Pseudomonas aeruginosa in positive urine, positive blood cultures, and rectal swabs. We performed a prospective analysis between January 2021 and June 2022, including overall 22,010 samples. Based on each hospital information, the sensitivity to detect CTX-M was 84%-100%, 90.9%-100%, and 75%-100% for urine, positive blood cultures, and enriched rectal swabs, respectively. On the other hand, the sensitivity to detect carbapenemases was 42.8%-100%, 75%-100%, and 66.6%-100% for urine, positive blood cultures, and enriched rectal swab, respectively. BL-DetecTool allows a rapid and reliable detection of ESBL and carbapenemases directly from urine, positive blood cultures, or enriched rectal swabs, being an easy technique to implement in the workflow of clinical microbiology laboratories.

IMPORTANCE

The assessed rapid assay to detect CTX-M beta-lactamases and carbapenemases directly from clinical samples can favor in the rapid detection of these mechanisms of resistance and hence the administration of a more adequate antimicrobial treatment.

Detection of rare carbapenemases in Enterobacterales-comparison of two colorimetric and three CIM-based carbapenemase assays

Rapid and reliable detection of carbapenemase-producing Enterobacterales (CPE) is crucial for prompt treatment and infection control. Most assays target the primary four enzymes (KPC, OXA-48-like, VIM, and NDM), often missing less common variants (e.g., GES, IMI, OXA-23, and OXA-58). Therefore, assays based on the hydrolysis of carbapenems are recommended in addition to differentiation tests such as PCR or immunochromatographic assays. The aim of this study was to compare the currently Clinical and Laboratory Standards Institute (CLSI)-recommended tests mCIM (modified carbapenem inactivation method) and Carba NP with new colorimetric tests (NitroSpeed-Carba NP) and novel variations of the carbapenem inactivation method (CIM) such as simplified CIM (sCIM) or modified zinc-supplemented CIM (mzCIM). The challenge collection included 205 clinical isolates, 139 CPE vs 66 non-CPE. Among all 205 isolates, the sensitivity/specificity of mCIM was 81.3%/98.5%, Carba NP 76.3%/100%, NitroSpeed-Carba NP 86.3%/78.8%, sCIM 100%/94%, and mzCIM 97.8%/98.5%. For rare carbapenemases (n = 48), the sensitivity of mzCIM (98.3%) and sCIM (100%) was higher than that of mCIM (60.4%), Carba NP (50%), or NitroSpeed-Carba NP (70.2%). Most indeterminate results occurred for mCIM (14.4%), Carba NP (8.2%), and sCIM (6.3%). The detection of rare carbapenemases remains challenging with the currently recommended assays. The CIM-based tests demonstrated superior sensitivity, with sCIM and mzCIM outperforming the currently recommended mCIM and Carba NP, especially among isolates with weakly hydrolyzing carbapenemases (e.g., OXA-23 and OXA-58). Although colorimetric assays provide more rapid results, laboratories have to be aware of the low sensitivity for rare carbapenemases. Both sCIM and the new mzCIM performed well, are cost-effective, and can easily be implemented in any laboratory.IMPORTANCEDetection of so-called rare carbapenemases (e.g., GES, IMI, OXA-23, and OXA-58) in Enterobacterales is challenging, and data on the performance of currently available assays are scarce. This study systematically assessed the performance of currently recommended and novel hydrolysis-based assays on a set of molecularly characterized isolates. It demonstrates that the currently recommended assays mCIM and Carba NP perform well on isolates producing common carbapenemases such as KPC, VIM, NDM, and OXA-48, but have only a moderate sensitivity in the detection of rare carbapenemases. In contrast, the newer CIM-based variants, sCIM and mzCIM, are equally capable of detecting frequent and uncommon carbapenemases. These assays could potentially help to improve our knowledge on the epidemiology of these "rare" enzymes.

[Evaluation of two phenotypic techniques and a commercial multiplex molecular panel for the detection of different carbapenemases]

OBJECTIVE

The prevalence of carbapenemase-producing Enterobacterales has increased in recent years and is considered an important public health problem.

METHODS

A total of 106 clinical samples were analyzed by different carbapenemase detection techniques: inhibition discs (ID), immunochromatographic test (ICT) and a genotypic method, comparing them with a multiplex RT-PCR as a reference method.

RESULTS

Overall, all 3 techniques exceeded 90% sensitivity, although with differences in the performance of some of them by carbapenemase type. DI had low specificity (62%) for OXA-48, while with TIC the sensitivity for NDM-type metallo-beta-lactamase (93%) was slightly lower than for OXA-48 (95%). The best results were obtained with the genotypic technique (100% overall performance).

CONCLUSIONS

Despite the lower sensitivity of TICs (especially in NDM carbapenemases) compared to molecular techniques, with the modification of the protocol we managed to increase this sensitivity and, together with the lower price, simplicity and speed, it makes this technique a good screening option.

Antibiotic resistance and genetic diversity among Pseudomonas aeruginosa isolated from urinary tract infections in Iran

Aims: To determine the antibiotic resistance and genetic diversity of Pseudomonas aeruginosa isolates. Methods: The antibiotic resistance, genetic diversity and the conjugate transformation among Pseudomonas aeruginosa collected from patients with urinary tract infection in Tehran, Iran, was investigated. Results: Antibiotic resistance against cefepime was seen in 51.74% of the isolates, followed by amikacin (47.76%). blaOXA-10 and blaVIM were the most prevalent extended-spectrum β-lactamase and metallo-β-lactamases genes, respectively. Five clusters (C1-C5) were obtained by pulse field gel electrophoresis and multilocus sequence typing revealed two strain types, ST235 and ST664. Conjugation detected blaOXA-48 and blaNDM genes were transferred to Escherichia coli K12. Conclusion: The resistance of P. aeruginosa to antibiotics is increasing, which highlights the need to determine the resistance patterns to design better treatment strategies.

Resist Acineto rapid immunological test for the detection of acquired carbapenemase producers among Acinetobacter spp

The Resist Acineto from Coris Bioconcept is a novel immunochromatographic test for detection of the major acquired carbapenemases (OXA-23, OXA-40, OXA-58, and NDM) identified in Acinetobacter spp. This rapid and easy-to-perform test showed an excellent specificity and sensitivity, with positive and negatives predictive values of 100% in both cases.

The role of the plasmid-mediated fluoroquinolone resistance genes as resistance mechanisms in pediatric infections due to Enterobacterales

Introduction

Fluoroquinolones (FQs) are not commonly prescribed in children, yet the increasing incidence of multidrug-resistant (MDR) Enterobacterales (Ent) infections in this population often reveals FQ resistance. We sought to define the role of FQ resistance in the epidemiology of MDR Ent in children, with an overall goal to devise treatment and prevention strategies.

Methods

A case-control study of children (0-18 years) at three Chicago hospitals was performed. Cases had infections by FQ-susceptible, β-lactamase-producing (bla) Ent harboring a non- or low-level expression of PMFQR genes (PMFQS Ent). Controls had FQR infections due to bla Ent with expressed PMFQR genes (PMFQR Ent). We sought bla genes by PCR or DNA (BD Max Check-Points assay®) and PMFQR genes by PCR. We performed rep-PCR, MLST, and E. coli phylogenetic grouping. Whole genome sequencing was additionally performed on PMFQS Ent positive isolates. Demographics, comorbidities, and device, antibiotic, and healthcare exposures were evaluated. Predictors of infection were assessed.

Results

Of 170 β-lactamase-producing Ent isolates, 85 (50%) were FQS; 23 (27%) had PMFQR genes (PMFQS cases). Eighty-five (50%) were FQR; 53 (62%) had PMFQR genes (PMFQR controls). The median age for children with PMFQS Ent and PMFQR Ent was 4.3 and 6.2 years, respectively (p = NS). Of 23 PMFQS Ent, 56% were Klebsiella spp., and of 53 PMFQR Ent, 76% were E. coli. The most common bla and PMFQR genes detected in PMFQS Ent were bla SHV ESBL (44%) and oqxAB (57%), and the corresponding genes detected in PMFQR Ent were bla CTX-M-1-group ESBL (79%) and aac(6')-Ib-cr (83%). Whole genome sequencing of PMFQS Ent revealed the additional presence of mcr-9, a transferable polymyxin resistance gene, in 47% of isolates, along with multiple plasmids and mobile genetic elements propagating drug resistance. Multivariable regression analysis showed that children with PMFQS Ent infections were more likely to have hospital onset infection (OR 5.7, 95% CI 1.6-22) and isolates containing multiple bla genes (OR 3.8, 95% CI 1.1-14.5). The presence of invasive devices mediated the effects of healthcare setting in the final model. Differences in demographics, comorbidities, or antibiotic use were not found.

Conclusions

Paradoxically, PMFQS Ent infections were often hospital onset and PMFQR Ent infections were community onset. PMFQS Ent commonly co-harbored multiple bla and PMFQR genes, and additional silent, yet transferrable antibiotic resistance genes such as mcr-9, affecting therapeutic options and suggesting the need to address infection prevention strategies to control spread. Control of PMFQS Ent infections will require validating community and healthcare-based sources and risk factors associated with acquisition.

Characterization of carbapenemase-producing Gram-negative bacilli: first report of blaNDM-1 in Enterobacter cloacae

INTRODUCTION

The spread of multidrug-resistant bacteria, particularly carbapenem-resistant Gram-negative bacilli (CR-GNB), has become a serious challenge for clinicians due to limited therapeutic options. The aim of the study was to investigate the prevalence of carbapenemase production among clinical isolates recovered from 352 samples collected in Tebessa hospital, Algeria.

METHODOLOGY

Bacterial isolates were identified by 16S RNA gene sequencing and susceptibility to antibiotics was determined by disk diffusion method. Carbapenem-resistant isolates were screened for carbapenemase production using modified carba Nordmann-Poirel test, modified Hodge test and imipenem-EDTA combined disc test. Extended-spectrum β-lactamases (ESBL) were detected using double-disk synergy test. Molecular characterization of carbapenemases and ESBL genes was performed by polymerase chain reaction (PCR) and sequencing.

RESULTS

A total of 85 Gram-negative bacilli isolates were recovered mainly from urine samples and were identified as: Klebsiella pneumoniae (17.65%), Serratia odorifera (15.29%), Escherichia coli (12.94%), Raoultella ornithinolytica, Enterobacter cloacae (11.76%), Serratia marcescens (10.59%), Morganella morganii (7.06%), Proteus mirabilis (5.88%), Acinetobacter baumannii (4.70%) and Pseudomonas aeruginosa (2.35%). All strains were resistant or intermediate to imipenem and/or ertapenem. ESBL, carbapenemase and metallo-beta-lactamases (MBL) phenotypes were detected in 19 (22.35%), 9 (10.59%) and 2 (2.35%) GNB isolates, respectively. PCR results in nine carbapenemase-producing GNB strains chosen showed the presence of one to four carbapenemase genes (blaGES, blaSME, blaNDM-1, blaVIM, blaGIM, blaSPM, blaOXA-48) in four strains; however, seven strains had at least one ESBL gene (blaTEM-1, blaCTXM-15, blaSHV).

CONCLUSIONS

In this study, we report the first incidence of blaNDM-1 gene in Enterobacter cloacae isolated from urine sample in Algeria.

Nutritional drinks and enteral feeds promote the growth of carbapenemase-producing Enterobacterales in conditions that simulate disposal in hospital sinks

BACKGROUND

Studies have shown that nutritional products are discarded via handwash sinks by healthcare workers, and this practice may promote bacterial growth, including growth of pathogens such as carbapenemase-producing Enterobacterales (CPE). Outbreaks and acquisition of CPE in nosocomial settings are associated with negative outcomes for patients and hospitals.

OBJECTIVES

To investigate the potential growth-promoting effect of nutritional support drinks (NSDs) and enteral tube-feed products (ETFPs) on CPE.

METHODS

Six different CPE strains were grown in five different diluted NSDs, five different diluted ETFPs, Mueller-Hinton broth (MHB) and M9 minimal salts media to simulate discarding a small volume of nutritional product in a u-bend, already containing liquid. CPE were enumerated at 0 h, 6 h and 24 h, and compared using two-way analysis of variance and Dunett test, with confidence levels at 95%. Spearman's r was used to measure the strength of correlation between component concentrations in nutritional products and CPE growth.

RESULTS

All NSDs and ETFPs promoted CPE growth that exceeded both M9 (negative growth control) and MHB (positive growth control). In several cases, growth in NSDs/ETFPs was significantly greater compared with growth in MHB.

CONCLUSION

Nutritional products support CPE growth under in-vitro conditions. The propensity of CPE to survive in drain pipework suggests that inappropriate product disposal may further nourish established CPE in these environmental reservoirs. The growth observed in diluted NSDs and ETFPs shows that modifiable practices should be optimized to mitigate the potential risk of CPE transmission from these reservoirs.

Proteus mirabilis - analysis of a concealed source of carbapenemases and development of a diagnostic algorithm for detection

OBJECTIVES

To analyse carbapenemases in Proteus mirabilis and assess the performance of carbapenemase detection assays.

METHODS

Eighty-one clinical P. mirabilis isolates with high-level resistance at least to ampicillin (>32 mg/L) or previous detection of carbapenemases were selected and investigated by three susceptibility testing methods (microdilution, automated susceptibility testing, and disk diffusion), six phenotypic carbapenemase assays (CARBA NP, modified carbapenemase inactivation method [CIM], modified zinc-supplemented CIM, simplified CIM, faropenem, and carbapenem-containing agar), two immunochromatographic assays, and whole-genome sequencing.

RESULTS

Carbapenemases were detected in 43 of 81 isolates (OXA-48-like [n = 13]; OXA-23 [n = 12]; OXA-58 [n = 12]; New Delhi metallo-β-lactamase (NDM) [n = 2]; Verona integron-encoded metallo-β-lactamase (VIM) [n = 2]; Imipenemase (IMP) [n = 1]; Klebsiella pneumoniae carbapenemase (KPC) [n = 1]). Carbapenemase-producing Proteus were frequently susceptible to ertapenem (26/43; 60%), meropenem (28/43; 65%), ceftazidime (33/43; 77%), and some even to piperacillin-tazobactam (9/43; 21%). Sensitivity/specificity of phenotypic tests were 30% (CI: 17-46%)/89% (CI: 75-97%) for CARBA NP, 74% (CI: 60-85%)/82% (CI: 67-91%) for faropenem, 91% (CI: 78-97%)/82% (CI: 66-92%) for simplified CIM, and 93% (CI: 81-99%)/100% (CI: 91-100%) for modified zinc-supplemented CIM. An algorithm for improved detection was developed, which demonstrated sensitivity/specificity of 100% (CI: 92-100%)/100% (CI: 91-100%) on the 81 isolates, and 100% (CI: 29-100%)/100% (CI: 96-100%) in a prospective analysis of additional 91 isolates. Interestingly, several OXA-23-producing isolates belonged to the same clonal lineage reported previously from France.

DISCUSSION

Current susceptibility testing methods and phenotypic tests frequently fail to detect carbapenemases in P. mirabilis, which could result in inadequate antibiotic treatment. In addition, the non-inclusion of blaOXA-23/OXA-58 in many molecular carbapenemase assays further impedes their detection. Therefore, the prevalence of carbapenemases in P. mirabilis is likely underestimated. With the herein proposed algorithm, carbapenemase-producing Proteus can be easily identified.

Molecular epidemiology of clinical isolation of carbapenem-resistant Enterobacterales and application of carbapenemase inhibitor enhancement test

OBJECTIVES

The prevalence of carbapenem-resistant Enterobacterales (CRE) presents a significant challenge in clinical anti-infective treatment. This study aims to investigate drug resistance and the molecular epidemiological characteristics of CRE in our area. Additionally, we seek to evaluate practicality of utilizing carbapenemase inhibitor enhancement test in clinical laboratory.

METHODS

Non-repeated CREs isolated from clinical specimens at Xiangya Hospital, Central South University, were collected. Minimum inhibitory concentration (MIC) combined with Kirby-Bauer (KB) assay was used to detect the drug susceptibility of the strains, and 13 carbapenemase-producing genes were detected by PCR. The phenotype of 126 strains of carbapenemase-producing Enterobacterales identified by PCR was detected by the carbapenemase inhibitor enhancement test to understand the agreement between the method and the gold standard PCR results.

RESULTS

Among 704 CRE strains examined, we observed significant drug resistance in 501 strains dentified as carbapenemase-producing Enterobacterales (CPE). Klebsiella pneumoniae was the predominant CPE strain, followed by Enterobacter cloacae and Escherichia coli. A total of 9 carbapenemase types were detected, including Klebsiella pneumoniae carbapenemase (KPC), New Delhi metallo-β-lactamase (NDM), Verona integron- encoded metallo-β-lactamases (VIM), imipenemase (IMP), oxacillinase-48 (OXA-48), and rare imipenem-hydrolyzing β-lactamase (IMI), adelaide imipenemase (AIM), Bicêtre carbapenemase (BIC), and guiana extended-spectrum β-lactamase (GES). The detection rate of KPC serine carbapenemase was 61.7% (309/501). The carbapenemase inhibitor enhancement test exhibited a 100% consistency rate for the strains producing Class A serine carbapenemase and/or Class B metallo-β-lactamases.

CONCLUSIONS

CRE strains in Changsha, Hunan, China, are wide distribution and exhibit carbapenemase production. The main mechanism of carbapenem resistance in these bacterias is predominatly attributed to the production of KPC serine carbapenemase. The presence of GES and IMI genes carried by Enterobacterales has been detected for the first time in this region. The carbapenemase inhibitor enhancement test has been proven to be an accurate method for detecting CRE producing Class A serine carbapenemase and/or Class B metallo-β-lactamases. This method offers simpicity of operation and ease of results interpretation, making it weel-suited meeting the clinical microbiology laboratory's reguirements for the detection of serine carbapenemase and metallo-β-lactamases.

Identification and Preliminary Hierarchisation of Selected Risk Factors for Carbapenemase-Producing Enterobacteriaceae (CPE) Colonisation: A Prospective Study

Drug-resistant bacteria are one of the main reasons of deaths worldwide. One of the significant groups of these bacteria are carbapenemase-producing Enterobacteriaceae (CPE). The goal of this cross-sectional study was the identification and hierarchisation of selected risk factors of CPE colonisation. To achieve that goal, we examined 236 patients for the presence of CPE using the standard method of anal swabs. The patients were divided into three groups: hospitalised patients; those chronically dialysed; those requiring home care. A very thorough medical interview was conducted for comorbidities. A statistical analysis relationship between comorbidities and locations of the patient's stay with the positive result of the culture was investigated. A significant relationship was demonstrated between the positive result of the culture and confirmed dementia, heart failure, connective tissue diseases, and established irregularities in the level of leukocytes. No significant relationship was demonstrated with the remaining comorbidities considered in the study. Afterwards these factors were compared for importance for the assessment of risk of a positive swab result-the biggest importance was found in establishing connective tissue disease. Next were dementia, abnormal values of leukocytes, heart failure, and at the end, stay at the orthopaedics ward. Conclusions: The study identified asymptomatic carriers of CPE, which demonstrates the need for further studies in order to identify infection risk factors. The connective tissue diseases are the most important variable which enable the prediction of CPE colonisation-the next ones are dementia, abnormal values of leukocytes, heart failure, and stay at the orthopaedics ward.

Incidence and Time-to-Onset of Carbapenemase-Producing Enterobacterales (CPE) Infections in CPE Carriers: a Retrospective Cohort Study

This study aimed to assess the proportion of carbapenemase-producing Enterobacterales (CPE) infections among all infectious episodes in CPE carriers, compare the time-to-onset of CPE infections with that of other infections, assess the mortality of patients with CPE infections, and identify risk factors for CPE infections in CPE carriers. A retrospective cohort study was performed over a 10-year period in our University Hospital, and 274 CPE carriers were identified. All infectious episodes within the first 6 months following the diagnosis of CPE rectal carriage were considered. Risk factor analysis for CPE infections in CPE carriers was performed by univariate and multivariate analyses. This study revealed an incidence of 24.1% (66/274) of CPE infection within 6 months of CPE carriage diagnosis. The 28-day all-cause mortality due to CPE infections was 25.7%. CPE infections represented 52.6% (70/133) of all infectious episodes in CPE carriers in the first 6 months following CPE carriage detection, and these significantly occurred earlier than non-CPE infections, with a median time of 15 versus 51 days, respectively (P < 0.01). Based on the multivariate analysis, prior neurological disease was the only risk factor associated with CPE infections in CPE carriers. CPE infections have an early onset, accounting for a large proportion of infections in CPE carriers, and are associated with high mortality. IMPORTANCE Carbapenemase-producing Enterobacterales (CPE) infections are emerging infections and may represent a therapeutic challenge, while effective antibiotic therapy is likely to be delayed. We aimed to assess the proportion of CPE infections in CPE carriers and to identify risk factors of CPE infections among this population that could guide empirical antibiotic therapy. We showed that CPE infections are frequent in CPE carriers, have an early onset after CPE carriage diagnosis, and represent a significant proportion of all infectious episodes in CPE carriers. No significant risk factors for CPE infections could be identified. Overall, this study suggests that empirical antibiotic treatment covering CPE might be initiated in CPE carriers at least in the first month after its diagnosis and in severe infections due to the high frequency and early occurrence of CPE infections in these patients.

Predictive score for patients with carbapenemase-producing enterobacterales colonization upon admission in a tertiary care hospital in an endemic area

OBJECTIVES

Carbapenemase-producing Enterobacterales (CPE) comprise important nosocomial pathogens worldwide. Colonized patients are the source of further dissemination in healthcare settings. Considering that timely detection of CPE carriers is pivotal but universal screening is unfeasible, we aimed to develop and validate a prediction score to detect patients harbouring CPE on hospital admission.

METHODS

The study was conducted in a tertiary care hospital located in a CPE endemic area. Rectal swabs were obtained from 2303 patients, screened shortly after hospital admission. The Enterobacterales isolated in cultures were examined for the presence of blaVIM, KPC, NDM, OXA-48 by PCR. Demographic data and patient history of the previous 6 months were recorded. Risk factors for CPE carriage were identified using a multivariable logistic regression model and a points-system risk score was developed. The discriminative ability of the risk score was assessed using the AUC and its predictive performance was validated in a second dataset of 1391 patients in a different time period.

RESULTS

Seven predictors were identified: previous CPE colonization or infection, prior hospitalization, stay in a long-term health care facility, history of ≥2 interventions, renal replacement therapy, diabetes with end-organ damage and Karnofsky score. The developed risk score in the derivation dataset ranged between 0 and 79 points, with an AUC of 0.84 in the derivation and 0.85 in the validation dataset.

CONCLUSIONS

This prediction tool may assist in identifying patients who are at risk of harbouring CPE on hospital admission in an endemic area and guide clinicians to implement prompt and appropriate infection control measures.

Comparative evaluation of phenotypic and genotypic methods for the rapid and cost-effective detection of carbapenemases in extensively drug resistant Klebsiella pneumoniae

PURPOSE

Carbapenemases are the enzymes that can hydrolyze carbapenems and other β-lactam antibiotics. These enzymes confer resistance to multiple antibiotics and act as a stumbling block in the treatment of infections caused by gram-negative bacteria. Therefore, rapid and specific detection of these enzymes is crucial for deciding the course of treatment and better clinical outcomes.

MATERIAL AND METHODS

This study was conducted to compare various phenotypic and PCR based methods for the detection of carbapenemases in carbapenem- and colistin-resistant Klebsiella pneumoniae. One hundred clinical isolates of extensively resistant Klebsiella pneumoniae were included in the study. Phenotypic detection for carbapenemases was performed by Rapidec® Carba NP (Biomerieux), modified carbapenem inactivation method (mCIM), imipenem-ethylenediaminetetraacetic acid disk synergy (EDS), double disk synergy test using mercaptopropionic acid (DDST-MPA), and combined disk method (CD) and for colistin by microbroth dilution method. Genotypic detection for carbapenemases and colistin resistance was performed by targeted PCR.

RESULTS

The sensitivity of Carba NP test and mCIM were positive in 95% and 96% respectively and specificity was 100% for both methods. The sensitivity of EDS, DDST-MPA, and CD were 55.6%, 88.9% and 54.5% respectively. Among the carbapenem resistance genes, blaOXA-48 (82%) genes were the most prevalent. Among metallo-beta lactamases, blaVIM (56%) was most common followed by blaNDM (54%) and blaIMP (20%). The mcr-1 gene for colistin resistance was not detected in any isolate.

CONCLUSION

Among the five phenotypic assays analyzed, the mCIM is the most simple, inexpensive, accurate and reproducible method for carbapenemase detection in Klebsiella pneumoniae. The DDST-MPA test provides the best sensitivity for the detection of carbapenemases, although specificity is low. These tests, when applied in a clinical laboratory and assessed by the microbiologist, can help in guiding the course of treatment.

Distribution and characteristics of carbapenem-resistant and extended-spectrum β-lactamase (ESBL) producing Escherichia coli in hospital effluents, sewage treatment plants, and river water in an urban area of Japan

Occurrence of profiles of the carbapenem-resistant Escherichia coli (CRE-E) and extended-spectrum β-lactamase (ESBL)-producing Escherichia coli (ESBL-E) in an urban river in a sub-catchment of the Yodo River Basin, one of the representative water systems of Japan was investigated. We conducted seasonal and year-round surveys for the antimicrobial-resistant bacteria (AMRB) and antimicrobial-resistance genes (AMRGs) in hospital effluents, sewage treatment plant (STP) wastewater, and river water; subsequently, contributions to wastewater discharge into the rivers were estimated by analyses based on the mass flux. Furthermore, the characteristics of AMRB in the water samples were evaluated on the basis of antimicrobial susceptibility tests. CRE-E and ESBL-E were detected in all water samples with mean values 11 and 1900 CFU/mL in the hospital effluent, 58 and 4550 CFU/mL in the STP influent, not detected to 1 CFU/mL in the STP effluent, and 1 and 1 CFU/mL in the STP discharge into the river, respectively. Contributions of the pollution load derived from the STP effluent discharged into the river water were 1 to 21%. The resistome profiles for bla_IMP, bla_TEM, and bla_CTX-M genes in each water sample showed that AMRGs were not completely removed in the wastewater treatment process in the STP, and the relative abundances of bla_IMP, bla_TEM, and bla_CTX-M genes were almost similar (P<0.05). Susceptibility testing of antimicrobial-resistant E. coli isolates showed that CRE-E and ESBL-E detected in wastewaters and river water were linked to the prevalence of AMRB in clinical settings. These results suggest the importance of conducting environmental risk management of AMRB and AMRGs in the river environment. To our knowledge, this is the first detailed study that links the medical environment to CRE-E and ESBL-E for evaluating the AMRB and AMRGs in hospital effluents, STP wastewater, and river water at the basin scale on the basis of mass flux as well as the contributions of CRE-E and ESBL-E to wastewater discharge into the river.

Rapid Detection of Carbapenemase-producing Enterobacteriaceae From Blood Culture Bottles of Known CPE Carriers: Real-world Experience

We used a rapid antigen test for the detection of carbapenemases directly from positive blood culture bottles of pediatric hemato-oncologic patients, known carriers of carbapenemase-producing enterobacteriaceae. Resistance mechanism was detected within 15 minutes of observing Gram-negative bacilli from a positive bottle, leading to treatment modification. This simple-to-use, inexpensive assay shortens the interval between empiric to tailored antimicrobial therapy.

Phenotypic characterization of carbapenem non-susceptible gram-negative bacilli isolated from clinical specimens

Background

Multidrug resistant, extremely drug-resistant, pan-drug resistant, carbapenem-resistant, and carbapenemase-producing gram-negative bacteria are becoming more common in health care settings and are posing a growing threat to public health.

Objective

The study was aimed to detect and phenotypically characterize carbapenem no- susceptible gram-negative bacilli at the Ethiopian Public Health Institute.

Materials and methods

A prospective cross-sectional study was conducted from June 30, 2019, to May 30, 2020, at the national reference laboratory of the Ethiopian Public Health Institute. Clinical samples were collected, inoculated, and incubated for each sample in accordance with standard protocol. Antimicrobial susceptibility testing was conducted using Kirby-Bauer disk diffusion method. Identification was done using the traditional biochemical method. Multidrug-resistant and extensively drug-resistant isolates were classified using a standardized definition established by the European Centre for Disease Prevention and Control and the United States Centers for Disease Prevention and Control. Gram-negative organisms with reduced susceptibility to carbapenem antibiotics were considered candidate carbapenemase producers and subjected to modified carbapenem inactivation and simplified carbapenem inactivation methods. Meropenem with EDTA was used to differentiate metallo-β-lactamase (MBL) from serine carbapenemase. Meropenem (MRP)/meropenem + phenylboronic acid (MBO) were used to differentiate Klebsiella pneumoniae carbapenemase (KPC) from other serine carbapenemase producing gram-negative organisms.

Results

A total of 1,337 clinical specimens were analyzed, of which 429 gram-negative bacterial isolates were recovered. Out of 429 isolates, 319, 74, and 36 were Enterobacterales, Acinetobacter species, and Pseudomonas aeruginosa respectively. In our study, the prevalence of multidrug-resistant, extensively drug-resistant, carbapenemase-producing, and carbapenem nonsusceptible gram-negative bacilli were 45.2%, 7.7%, 5.4%, and 15.4% respectively. Out of 429 isolates, 66 demonstrated reduced susceptibility to the antibiotics meropenem and imipenem. These isolates were tested for carbapenemase production of which 34.8% (23/66) were carbapenemase producers. Out of 23 carbapenemase positive gram-negative bacteria, ten (10) and thirteen (13) were metallo-beta-lactamase and serine carbapenemase respectively. Three of 13 serine carbapenemase positive organisms were Klebsiella pneumoniae carbapenemase.

Conclusion

This study revealed an alarming level of antimicrobial resistance (AMR), with a high prevalence of multidrug-resistant (MDR) and extremely drug-resistant, carbapenemase-producing gram-negative bacteria, particularly among intensive care unit patients at the health facility level. These findings point to a scenario in which clinical management of infected patients becomes increasingly difficult and necessitates the use of “last-resort” antimicrobials likely exacerbating the magnitude of the global AMR crisis. This mandates robust AMR monitoring and an infection prevention and control program.

Prevalence of non-extended spectrum β-lactamases SHV-1 and TEM-1 or -2 types in multidrug-resistant Enterobacteriaceae in northern Iran

The present study aimed to evaluate TEM-1 or -2 and SHV-1 β-lactamases frequency in multidrug-resistant (MDR) Enterobacteriaceae isolated from patients' urine in northern Iran. The resistance pattern to 20 antibiotics and ESBL production in 200 MDR Enterobacteriaceae was detected using the disk diffusion test and double-disk synergy test (DDST), respectively. Multiplex PCR was applied to detect bla_{TEM-1 or -2} and bla_SHV genes in isolates. DDST findings were inconsistent with multiplex PCR results. The distribution of each of bla_{TEM-1 or -2} and bla_SHV genes, either alone or in combination, in the ESBL-producing isolates was higher than the non-ESBL-producing isolates. There was a significant effect of the presence of bla_{TEM-1 or -2} gene on resistance to cephalotin at the p < 0.01 level and cefepime, tetracycline, and streptomycin at the P < 0.05 level, and the presence of bla_SHV-1 gene on resistance to fosfomycin at the P < 0.05 level as well as the presence both bla_{TEM-1 or -2} and bla_SHV-1 genes on resistance to cephalotin and fosfomycin at the P < 0.01 level. In all isolates, ESBL production, except for cephalotin resistance, did not improve resistance to other antibiotics used and even non-ESBL-producing isolates showed higher resistance to antibiotics compared to ESBL-producing isolates. It seems that mechanisms other than production of ESBL to be involved as part of the resistance mechanisms of the studied isolates against the used antibiotics. For epidemiological studies, both phenotypic and molecular tests must be included to identify the bla_{TEM-1 or -2} and bla_SHV-1 genotypes to ensure infection prevention and control.

Multiplex lateral flow immunochromatographic assay is an effective method to detect carbapenemases without risk of OXA-48-like cross reactivity

BACKGROUND

It is essential to detect carriers of carbapenemase-producing Enterobacterales in order to implement infection control measures. The objectives of this study was to evaluate the NG-Test® CARBA 5 (CARBA 5) assay for detection of five carbapenemases and to assess the cross reactivity of other OXA-type carbapenemases with the OXA-48-like specific antibodies.

METHODS

A total of 197 Enterobacterales isolates were tested. To evaluate the cross reactivity, 73 carbapenem-resistant A. baumannii, harboring OXA-type variants, were tested. Polymerase chain reaction (PCR) served as gold standard for carbapenemase identification.

RESULTS

Excellent agreement was found between PCR and CARBA 5, for all but one isolate. The single false positive result (a blaSME positive S. marcescens isolate) was incorrectly positive for blaOXA-48 by CARBA 5. No cross reactivity was observed. The sensitivity and specificity were 100.0% and 98.0%, respectively.

CONCLUSIONS

The CARBA 5 assay is highly sensitive and specific and is recommended as a tool for the detection of the main carbapenemases of interest in clinical microbiology laboratories.

Evaluation of the new BL-RED (β-Lactamase Rapid Electrochemical Detection) test in positive blood culture broths

The rapid detection of extended-spectrum β-lactamase Enterobacterales (ESBL-E) in a positive blood culture is important in order to initiate an appropriate antibiotic therapy and thus decrease mortality. We evaluated the new BL-RED (β-Lactamase Rapid Electrochemical Detection) test in 100 positive blood culture broths to detect (in ten minutes) the presence or absence of ESBL-E. The BL-RED test appears to be an easy, rapid and reliable test to detect the presence of ESBL directly in Gram negative bacilli-positive blood culture broths, with good performances (sensibility =97.3%, specificity =90.5%, predictive positive value =85.7% and predictive negative value =98.3%). This test could be useful for therapeutic decisions and adjustments of sepsis empirical antibiotic therapy, particularly in wards where the ecology is unfavorable, such as in intensive care units.

Early prediction models for extended-spectrum β-lactamase-producing Escherichia coli infection in emergency department: A protocol for systematic review and meta analysis

BACKGROUND

Resistance in gram-negative bacteria has gained great importance in recent decades and one reason is the rapid increase of extended spectrum β-lactamase (ESBL)-producing bacteria as a growing problem worldwide. The increasing proportion of ESBL-producing Enterobacteriaceae (ESBL-E) infections acquired in the emergency community is a new feature of ESBLs epidemiology. Early recognition of patients with extended-spectrum β-lactamase-producing Escherichia coli infection is important in the emergency department. To mitigate the burden on the healthcare system, while also providing the best possible care for patients, early recognition of the infection is needed.

METHODS

For the acquisition of required data of eligible prospective/retrospective cohort study or randomized controlled trials (RCTs), we will search for publications from PubMed, Web of science, EMBASE, Cochrane Library, Google scholar. Two independent reviewers will read the full English text of the articles, screened and selected carefully, removing duplication. Then we evaluate the quality and analyses data by Review Manager (V.5.4). Results data will be pooled and meta-analysis will be conducted if there's 2 eligible studies considered.

RESULTS

This systematic review and meta-analysis will evaluate the value of the early prediction models for Extended-spectrum β-lactamase-producing E coli infection in emergency department.

CONCLUSIONS

This systematic review and meta-analysis will provide clinical evidence for predicting Extended-spectrum β-lactamase-producing E coli infection in emergency department, inform our understanding of the value of the predictive model in predicting Extended-spectrum β-lactamase-producing E coli infection in emergency department in the early stage. The conclusions drawn from this study may be beneficial to patients, clinicians, and health-related policy makers.

STUDY REGISTRATION NUMBER

INPLASY202130049.

Evaluation of CARBA PAcE, a novel rapid test for detection of carbapenemase-producing Enterobacterales

Introduction. Carbapenemase-producing Enterobacterales (CPE) are an increasing threat to global health. Fast detection is crucial for patient management and outbreak control.Hypothesis/Gap statement. Recently, a new commercial colorimetric test, CARBA PAcE, was released that has not yet been scientifically evaluated.Aim. Our goals were to evaluate the performance of CARBA PAcE using a large variety of different CPE.Methodology. CARBA PAcE was challenged with 107 molecularly characterized CPE and 53 non-CPE controls. Isolates were grown on Mueller-Hinton agar (MHA); in the case of a false-negative result, isolates were additionally inoculated on Columbia blood agar (CBA) and CARBA PAcE was repeated. The test was performed according to the manufacturer's protocol.Results. CARBA PAcE showed an overall sensitivity and specificity of 72 % [confidence interval (CI) 62-80 %] and 91 % (CI 79-97 %), respectively, when isolates were grown on MHA. With growth on CBA, detection improved (especially of metallo-β-lactamases), resulting in an extrapolated sensitivity of 89 % (CI 81-94 %) for all carbapenemases and 96 % (CI 89-99 %) for the four major carbapenemases (NDM, OXA-48-like, KPC, VIM).Conclusion. CARBA PAcE is a simple and very rapid test for the detection of CPE which performs well for the major carbapenemases when isolates are grown on CBA. Laboratories should be aware of the limitations of this assay, such as moderate sensitivity when isolates are grown on more challenging agars such as MHA and the poor detection of some rare carbapenemases (e.g. IMI, OXA-58).

Comparison of four low-cost carbapenemase detection tests and a proposal of an algorithm for early detection of carbapenemase-producing Enterobacteriaceae in resource-limited settings

Rapidly progressing antibiotic resistance is a great challenge in therapy. In particular, the infections caused by carbapenem-resistant Enterobacteriaceae (CRE) are exceedingly difficult to treat. Carbapenemase production is the predominant mechanism of resistance in CRE. Early and accurate identification of carbapenemase-producing carbapenem-resistant Enterobacteriaceae (CP-CRE) is extremely important for the treatment and prevention of such infections. In the present study, four phenotypic carbapenemase detection tests were compared and an algorithm was developed for rapid and cost-effective identification of CP-CRE. A total of 117 Enterobacteriaceae (54 CP-CRE, 3 non-CP-CRE, and 60 non-CRE) isolates were tested for carbapenemase production using modified Hodge test (MHT), modified carbapenem inactivation method (mCIM), Carba NP test (CNPt), and CNPt-direct test. The overall sensitivity/specificity values were 90.7%/92.1% for MHT, 100%/100% for mCIM, 75.9%/100% for CNPt, and 83.3%/100% for CNPt-direct. OXA-48-like enzymes were detected with 93.2% sensitivity by MHT and >77.3% sensitivity by two Carba NP tests. MHT could only detect half of the NDM carbapenemase producers. CNPt-direct exhibited enhanced sensitivity compared to CNPt (100% vs 25%) for detection of NDM producers. Considering these findings we propose CNPt-direct as the first test followed by mCIM for rapid detection of CP-CRE. With this algorithm >80% of the CP-CRE could be detected within 24 hours from the time the sample is received and 100% CP-CRE could be detected in day two. In conclusion, mCIM was the most sensitive assay for the identification of CP-CRE. CNPt-direct performed better than CNPt. An algorithm consisting CNPt-direct and mCIM allows rapid and reliable detection of carbapenemase production in resource-limited settings.

β-Lactamase triggered visual detection of bacteria using cephalosporin functionalized biomaterials

We report the conjugation of a chromogenic cephalosporin β-lactamase (βL) substrate to polymers and integration into biomaterials for facile, visual βL detection. Identification of these bacterial enzymes, which are a leading cause of antibiotic resistance, is critical in the treatment of infectious diseases. The βL substrate polymer conjugate undergoes a clear to deep yellow color change upon incubation with common pathogenic Gram-positive and Gram-negative bacteria species. We have demonstrated the feasibility of formulating hydrogels with the βL substrate covalently tethered to a poly(ethylene glycol) (PEG) polymer matrix, exhibiting a visible color change in the presence of βLs. This approach has the potential to be used in diagnostic biomaterials for point-of-care detection of βL-producing bacteria, helping combat the spread of drug resistant microbes.

Human faeces-associated extended-spectrum β-lactamase-producing Escherichia coli discharge into sanitation systems in 2015 and 2030: a global and regional analysis

BACKGROUND

Improving management of and treatment within sanitation waste streams could slow the development and transmission of antimicrobial-resistant organisms, but the magnitude of impact has not been quantified. Extended-spectrum β-lactamase (ESBL)-producing Escherichia coli are a major cause of antimicrobial-resistant infections and are frequently detected in faecal waste streams, making them model indicators of the distribution of antimicrobial-resistant organisms that are transmitted through the faecal-oral route. We aimed to estimate the mass of faeces containing ESBL-producing E coli entering different levels of the sanitation ladder globally and by WHO region to determine the global scale at which sanitation infrastructure serves as a vehicle for dissemination of antimicrobial-resistant organisms.

METHODS

In this global and regional analysis, we used publicly available sanitation coverage data from the WHO/UNICEF Joint Monitoring Programme and most recent available scientific literature on human faecal production (2018) and carriage of ESBL-producing E coli by healthy individuals (2016) to estimate the quantity of faeces that has been discharged that contains ESBL-producing E coli for 2015 and projected for 2030. We estimated the mass of faeces containing ESBL-producing E coli by WHO region and at different levels of the Sustainable Development Goal sanitation ladder-ie, into at-least basic (ie, safely managed or basic) systems, limited systems, and unimproved systems, and via open defecation. We modelled three scenarios in which the proportion of ESBL-producing E coli among all E coli that was excreted by carriers varied on the basis of the scientific literature: 100% (scenario A), 10% (scenario B), or 1% (scenario C).

FINDINGS

Under scenario B, we estimated that approximately 19 billion kg of faeces carrying ESBL-producing E coli was excreted in 2015 globally. Approximately 65·8% (1·2-120 billion kg depending on modelled scenario) of this faecal biomass was managed in at-least basic sanitation systems, 8·4% (160 million-16 billion kg) in limited sanitation systems, 14·4% (270 million-27 billion kg) in unimproved sanitation systems, and 11·4% (220 million-22 billion kg) was openly defecated. The regions with the highest proportion of openly defecated faeces containing ESBL-producing E coli were the South-East Asia (29·4%) and African (21·8%) regions. The South-East Asia, Western Pacific, and African regions produced 524 billion kg (63%) of the total global human faecal biomass, but 16·9 billion kg (90%) of faeces containing ESBL-producing E coli under scenario B. By 2030, estimates under scenario B will have approximately doubled to 37·6 billion kg of faeces carrying ESBL-producing E coli under the most conservative projections.

INTERPRETATION

At-least basic sanitation does not guarantee effective removal or inactivation of antimicrobial-resistant organisms from faecal biomass. However, our findings indicate the need for mitigating transport of antimicrobial-resistant organisms via sanitation systems that are not safely managed, including open defecation, which might result in direct environmental discharge and subsequent risk of transmission back to humans.

FUNDING

None.

Extended-spectrum beta-lactamase (ESBL) producing Enterobacterales in stool surveillance cultures of preterm infants are no risk factor for necrotizing enterocolitis: a retrospective case-control study over 12 years

Purpose

Microbial dysbiosis has been found preceding necrotizing enterocolitis (NEC) in preterm infants; thus, we aimed to investigate whether there is evidence that neonates with extended-spectrum beta-lactamase-producing Enterobacterales (ESBL-E) positive stool cultures are at higher risk for NEC at the NICU.

Methods

We included very preterm inborn infants of ≤ 32 weeks of gestational age being fecal carriers of ESBL-E and compared them with 1:1 matched (gestational age, birth weight, gender and year) controls tested negative for ESBL-E in the stool between 2005 and 2016. An association with NEC was defined as the first detection of ESBL-E before or at the time of definite diagnosis of NEC.

Results

During the study period, we diagnosed 217 infants with a total of 270 ESBL-E. We identified ten different species with ESBL-producing Klebsiella oxytoca being the most common one (46%) followed by Klebsiella pneumoniae (19%), and Citrobacter freundii (17%). Ten out of 217 infants had any kind of NEC in the case group compared to two of the controls (p < 0.01), but only four cases with predefined criteria were associated with NEC ≥ stage IIa (1.8 vs. 0.5%, p = 0.089, OR 4.1, CI95% 0.45–36.6). NEC mortality rate was 2/8 (25%).

Conclusions

We observed a threefold increase of ESBL-E in stool surveillance cultures during study time and germs were dominated by ESBL-producing Klebsiella spp. There was no evidence that preterm infants colonized with ESBL-E in the stool were at higher risk for definite NEC.

A cephalosporin-chemiluminescent conjugate increases beta-lactamase detection sensitivity by four orders of magnitude

The expression of beta-lactamases in bacteria is a central cause of drug resistance. In this report, we present a beta-lactamase chemiluminescent probe, termed CCP, which can for the first time detect beta-lactamase activity via chemiluminescence and can detect beta lactamase with a sensitivity that is 4-orders of magnitude higher than the commercially available fluorescent lactamase substrate fluorocillin.

Development and Evaluation of a Novel Protein-Based Assay for Specific Detection of KPC β-Lactamases from Klebsiella pneumoniae Clinical Isolates

Carbapenemases confer resistance to nearly all β-lactam antibiotics. The extensive spread of carbapenemase-producing multidrug-resistant bacteria contributes significantly to hospital-acquired infections. We have developed a novel protein-based binding assay that identifies KPC β-lactamases from clinical isolates. We used the protein-protein interaction between KPCs and a soluble β-lactamase inhibitory protein (BLIP) variant, BLIPK74T/W112D, which specifically inhibits KPCs but not other β-lactamases. In this assay, BLIPK74T/W112D was allowed to form complexes with KPC-2 in bacterial cell lysates and then extracted using His tag binding resins. We demonstrated the presence of KPC-2 by monitoring the hydrolysis of a colorimetric β-lactam substrate. Also, to further increase the accuracy of the method, a BLIPK74T/W112D-mediated inhibition assay was developed. The binding and inhibition assays were validated by testing 127 Klebsiella pneumoniae clinical isolates with known genome sequences for the presence of KPC. Our assays identified a total of 32 strains as KPC-2 producers, a result in 100% concordance with genome sequencing predictions. To further simplify the assay and decrease the time to obtain results, the BLIPK74T/W112D protein was tested in combination with the widely used Carba-NP assay. For this purpose, the genome-sequenced K. pneumoniae strains were tested for the presence of carbapenemases with the Carba-NP test with and without the addition of BLIPK74T/W122D The test accurately identified carbapenemase-producing strains and the addition of BLIPK74T/W112D allowed a further determination that the strains contain KPC carbapenemase. Thus, the BLIPK74T/W112D protein is an effective sensor to specifically detect KPC β-lactamases produced by clinical isolates.IMPORTANCE Infections caused by carbapenem-resistant Enterobacteriaceae are associated with high therapeutic failure and mortality rates. Thus, it is critical to rapidly identify clinical isolates expressing KPC β-lactamases to facilitate administration of the correct antibiotic treatment and initiate infection control strategies. To address this problem, we developed a protein-based, KPC-specific binding assay in combination with a cell lysate inhibition assay that provided a 100% identification rate of KPC from clinical isolates of known genomic sequence. In addition, this protein sensor was adapted to the Carba-NP assay to provide a rapid strategy to detect KPC-producing isolates that will facilitate informed treatment of critically ill patients.

Assessment of extended-spectrum β-lactamase (ESBLs) - producing Escherichia coli from minced meat of cattle and swab samples and hygienic status of meat retailer shops in Jimma town, Southwest Ethiopia

BACKGROUND

The impact of animals sources of food as a possible reservoir for extended-spectrum β-lactamase (ESBL) - Producing E. coli, and the dissemination of such strains into the food production chain need to be assessed. This study was aimed to assess the presence and antimicrobial susceptibility patterns of ESBLs - producing E. coli isolates from minced meat and environmental swab samples at meat retailer shops of Jimma town, Southwest Ethiopia.

METHODOLOGY

A cross-sectional descriptive study was conducted from March to June, 2016. A total of 168 minced meat and swab samples were first enriched by buffered peptone water (BPW) for overnight and streaked onto MacConkey agar. Double disk synergy (DDS) method was used for detection of ESBL-producing strains. A disk of amoxicillin + clavulanic acid (20/10 μg) was placed in the center of Mueller-Hinton agar plate, and cefotaxime (30 μg) and ceftazidime (30 μg) were placed at a distance of 20 mm from the central disk. Checklist was used to assess hygienic status of butcher shops and practices meat handlers.

RESULTS

A total of 35 (20.80%) biochemically confirmed E. coli were obtained from 168 samples. Of these, 21 (23.9%) of them were detected from 88 minced meat and the other 14 (17.5%) from 80 swab samples taken from butcher's hand, knives, chopping board and protective clothing. From 35 E. coli isolates, 7(20%) of them were confirmed as ESBL- producers. Among ESBL- producing strains, 85.7% were resistant for cefotaxime and ceftriaxone and 71.4% for ceftazidime. Among non-ESBLs-producing strains only seven isolates were resistant to third generation cephalosporin. All E. coli isolates were resistant to ampicillin, penicillin and erythromycin, and susceptible to amikacin. Poor hygienic status of butcher shops and unhygienic practice of meat handlers were observed.

CONCLUSION

The detections of ESBLs- producing strains could be contributed for the increment of multi drug resistant isolates. This study also concluded that, unhygienic meat handling and processing practice can contribute for contaminations of meat. Thus, strategies should be planned and implemented to improve the knowledge and practice of butchers about handling and processing of meat.

Swine waste: A reservoir of high-risk blaNDM and mcr-1

Multidrug resistance associated with pigs not only affects pig production but also threatens human health by influencing the farm surrounding and contaminating the food chain. This paper focused on the occurrence and prevalence of high-risk resistance genes (using bla_NDM and mcr-1 as marker genes) in two Chinese swine farms, and investigated their fate and seasonal changes in piggery wastewater treatment systems (PWWTSs). Results revealed that bla_NDM and mcr-1 were prevalent in both confined swine farms, and even prevailed through various processing stages of PWWTSs. Moreover, the abundance of bla_NDM and mcr-1 in winter was higher than that in summer, with 0.01-1.01 logs variation in piggery wastewater. Of concern is that considerable amounts of bla_NDM and mcr-1 were present in final effluent that is applied to farmland (up to 10²-10⁴copies/mL), raising the risk of propagation to indigenous bacteria. Worse still, those pig-derived isolates harboring the bla_NDM/mcr-1 gene were confirmed to spread multidrug resistance to other bacteria, which further increased their dissemination potential in agricultural environment. This study highlights the prevalence of bla_NDM and mcr-1 in swine farms, meanwhile, also emphasizes the necessary to mitigate the release and propagation of these high-risk genes from swine farms following land fertilization and wastewater usage.

Surface-Bound Antibiotic for the Detection of β-Lactamases

Antimicrobial resistance (AMR) has been identified as a major threat to public health worldwide. To ensure appropriate use of existing antibiotics, rapid and reliable tests of AMR are necessary. One of the most common and clinically important forms of bacterial resistance is to β-lactam antibiotics (e.g., penicillin). This resistance is often caused by β-lactamases, which hydrolyze β-lactam drugs, rendering them ineffective. Current methods for detecting these enzymes require either time-consuming growth assays or antibiotic mimics such as nitrocefin. Here, we report the development of a surface-bound, clinically relevant β-lactam drug that can be used to detect β-lactamases and that is compatible with a range of high-sensitivity, low-cost, and label-free analytical techniques currently being developed for point-of-care-diagnostics. Furthermore, we demonstrate the use of these functionalized surfaces to selectively detect β-lactamases in complex biological media, such as urine.

Proteomic analysis of ESBL-producing Escherichia coli under bentonite condition

The dissemination of extended spectrum beta-lactamases (ESBL) genes through gene transfer attracts wide attention. Bentonite is widely used as a feed additive in an animal-breeding environment. In order to obtain a better understanding of the effect of bentonite on Escherichia coli carrying ESBL gene, proteomic analysis was carried out to screen the key proteins. The results showed that a total of 31 proteins were differentially expressed, including 21 up-regulated proteins and 10 down-regulated proteins. These proteins were involved in biosynthetic process, metabolic process, stress response, transport, anaerobic respiration, proteolysis, hydrolase, protein folding, transcription, salvage, and other. The transcriptional level of four genes (mipA, gntY, tldD, and arcA) was in consensus with proteomic results. This study revealed the differentially expressed proteins involved when E. coli was incubated under bentonite and PBS condition, which implied the possibility that bentonite may promote the transfer of ESBL gene between E. coli.

Attributable sources of community-acquired carriage of Escherichia coli containing β-lactam antibiotic resistance genes: a population-based modelling study

BACKGROUND

Extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC), plasmid-mediated AmpC-producing E coli (pAmpC-EC), and other bacteria are resistant to important β-lactam antibiotics. ESBL-EC and pAmpC-EC are increasingly reported in animals, food, the environment, and community-acquired and health-care-associated human infections. These infections are usually preceded by asymptomatic carriage, for which attributions to animal, food, environmental, and human sources remain unquantified.

METHODS

In this population-based modelling study, we collected ESBL and pAmpC gene data on the Netherlands population for 2005-17 from published datasets of gene occurrences in E coli isolates from different sources, and from partners of the ESBL Attribution Consortium and the Dutch National Antimicrobial Surveillance System. Using these data, we applied an established source attribution model based on ESBL-EC and pAmpC-EC prevalence and gene data for humans, including high-risk populations (ie, returning travellers, clinical patients, farmers), farm and companion animals, food, surface freshwater, and wild birds, and human exposure data, to quantify the overall and gene-specific attributable sources of community-acquired ESBL-EC and pAmpC-EC intestinal carriage. We also used a simple transmission model to determine the basic reproduction number (R₀) in the open community.

FINDINGS

We identified 1220 occurrences of ESBL-EC and pAmpC-EC genes in humans, of which 478 were in clinical patients, 454 were from asymptomatic carriers in the open community, 103 were in poultry and pig farmers, and 185 were in people who had travelled out of the region. We also identified 6275 occurrences in non-human sources, including 479 in companion animals, 4026 in farm animals, 66 in wild birds, 1430 from food products, and 274 from surface freshwater. Most community-acquired ESBL-EC and pAmpC-EC carriage was attributed to human-to-human transmission within or between households in the open community (60·1%, 95% credible interval 40·0-73·5), and to secondary transmission from high-risk groups (6·9%, 4·1-9·2). Food accounted for 18·9% (7·0-38·3) of carriage, companion animals for 7·9% (1·4-19·9), farm animals (non-occupational contact) for 3·6% (0·6-9·9), and swimming in freshwater and wild birds (ie, environmental contact) for 2·6% (0·2-8·7). We derived an R₀ of 0·63 (95% CI 0·42-0·77) for intracommunity transmission.

INTERPRETATION

Although humans are the main source of community-acquired ESBL-EC and pAmpC-EC carriage, the attributable non-human sources underpin the need for longitudinal studies and continuous monitoring, because intracommunity ESBL-EC and pAmpC-EC spread alone is unlikely to be self-maintaining without transmission to and from non-human sources.

FUNDING

1Health4Food, Dutch Ministry of Economic Affairs, and the EU's Horizon-2020 through One-Health European Joint Programme.

Hospital effluent: A reservoir for carbapenemase-producing Enterobacterales?

Antimicrobial resistance is a major public health concern. Carbapenemase-producing Enterobacterales (CPE) represent a significant health threat as some strains are resistant to almost all available antibiotics. The aim of this research was to examine hospital effluent and municipal wastewater in an urban area in Ireland for CPE. Samples of hospital effluent (n = 5), municipal wastewater before (n = 5) and after (n = 4) the hospital effluent stream joined the municipal wastewater stream were collected over a nine-week period (May-June 2017). All samples were examined for CPE by direct plating onto Brilliance CRE agar. Isolates were selected for susceptibility testing to 15 antimicrobial agents in accordance with EUCAST criteria. Where relevant, isolates were tested for carbapenemase-encoding genes by real-time PCR. CPE were detected in five samples of hospital effluent, one sample of pre-hospital wastewater and three samples of post-hospital wastewater. Our findings suggest hospital effluent is a major contributor to CPE in municipal wastewater. Monitoring of hospital effluent for CPE could have important applications in detection and risk management of unrecognised dissemination of CPE in both the healthcare setting and the environment.

ESBL and AmpC β-Lactamases in Clinical Strains of Escherichia coli from Serra da Estrela, Portugal

Background and Objectives: Given the considerable spatial, temporal, and ecological factors, heterogeneity, which affects emergency response, persistence, and dissemination of genetic determinants that confer microorganisms their resistance to antibiotics, several authors claim that antibiotics' resistance must be perceived as an ecological problem. The aim of this study was to determine the prevalence of broad-spectrum bla genes, not only Extended-spectrum β-lactamases (ESBL) but also AmpC-types, in clinical strains of Escherichia coli isolated from Portugal (in the highest region of the country, Serra da Estrela) to disclose susceptibility profiles among different genotypes, and to compare the distribution of bla genes expressing broad-spectrum enzymes. Materials and Methods: Clinical strains of Escherichia coli presenting resistance to third generation (3G) cephalosporins and susceptibility to inhibition by clavulanic acid were studied by means of phenotypic and molecular profiling techniques for encoding β-lactamases genes. Results: Strains were mainly isolated from hospital populations (97%). Molecular analysis enabled the detection of 49 bla genes, in which 55% (27/49) were identified as blaOXA-1-like, 33% (16/49) as blaCTX-M-group-1, 10% (5/49) as blaTEM, and 2% (1/49) were identified as genes blaCIT (AmpC). Among all blaOXA-1-like detected, about 59% of strains expressed at least another bla gene. Co-production of β-lactamases was observed in 40% of strains, with the co-production of CTX-M group 1 and OXA-1-like occurring as the most frequent. Conclusions: This is the first study using microorganisms isolated from native people from the highest Portuguese mountain regions, showing an unprecedent high prevalence of genes blaOXA-1-like in this country.

Whole genome sequencing reveals resemblance between ESBL-producing and carbapenem resistant Klebsiella pneumoniae isolates from Austrian rivers and clinical isolates from hospitals

In 2016, the Austrian Agency for Health and Food Safety started a pilot project to investigate antimicrobial resistance in surface water. Here we report on the characterisation of carbapenem resistant and ESBL-producing K. pneumoniae isolates from Austrian river water samples compared to 95 clinical isolates recently obtained in Austrian hospitals. Ten water samples were taken from four main rivers, collected upstream and downstream of major cities in 2016. For subtyping and comparison, public core genome multi locus sequence typing (cgMLST) schemes were used. The presence of AMR genes, virulence genes and plasmids was extracted from whole genome sequence (WGS) data. In total three ESBL-producing strains and two carbapenem resistant strains were isolated. WGS based comparison of these five water isolates to 95 clinical isolates identified three clusters. Cluster 1 (ST11) and cluster 2 (ST985) consisted of doublets of carbapenem resistant strains (one water and one clinical isolate each). Cluster 3 (ST405) consisted of three ESBL-producing strains isolated from one water sample and two clinical specimens. The cities, in which patient isolates of cluster 2 and 3 were collected, were in concordance with the water sampling locations downstream from these cities. The genetic concordance between isolates from river water samples and patient isolates raises concerns regarding the release of wastewater treatment plant effluents into surface water. From a public health perspective these findings demand attention and strategies are required to minimize the spread of multiresistant strains to the environment.

A survey of extended-spectrum β-lactamase-producing Enterobacteriaceae in environmental water in Okinawa Prefecture of Japan and relationship with indicator organisms

Surveys of extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-pE) in stream water and untreated wastewater were carried out in Okinawa Prefecture, Japan. Thirty-six samples of water were collected from 18 streams in Okinawa Prefecture, as well as ten samples of wastewater flowing into four wastewater treatment plants (WWTPs). We investigated bacterial species, Escherichia coli O antigen, ESBL phenotype, ESBL genotype, and pulsed-field gel electrophoresis (PFGE) type of isolates, and total viable count and fecal coliforms as indicator organisms. The relation between indicator organisms and ESBL-pE was also validated using the same samples. A total of 141 ESBL-pE including 107 E. coli, 15 Klebsiella pneumoniae, 2 Proteus mirabilis, and 17 other species was isolated from stream water and wastewater. Of the 141 ESBL-pE, 14.9% and 54.6% were found to be blaCTX-M-15 and blaCTX-M-14-like types, respectively, which have been found in hospital isolates in Okinawa. Two pairs of possibly related patterns according to PFGE criteria were isolated from stream water and wastewater in two districts. When ESBL-pE was significantly isolated, total viable count and fecal coliform boundaries were ≥ 6.0 × 10³ CFU/ml and ≥ 4.3 × 10² most probable number/100 ml, respectively. These results suggested that ESBL-pE isolated from stream water is human derived, and that total viable count and fecal coliforms will be useful as indicators for confirming the spread of ESBL-pE to the environment by means of simple hygiene surveys.

Occurrence of super antibiotic resistance genes in the downstream of the Yangtze River in China: Prevalence and antibiotic resistance profiles

The super antibiotic resistance genes (SARGs) demonstrate more severe threats than other antibiotic resistance genes while have not received enough attention in the environment. The study explored the prevalence and the antibiotic tolerance profiles of two typical SARGs, MCR-1 and NDM-1, and their hosting bacteria in the downstream of the Yangtze River and the nearby wastewater treatment plant (WWTP) and drinking water treatment plant (DWTP). Results indicated that MCR-1 and NDM-1 were prevalent in the influent and biological units of the WWTP. Their hosting bacteria were effectively removed, but 2.49 × 10⁸ copies/L MCR-1 and 7.00 × 10⁶ copies/L NDM-1 were still persistent in the effluent. In the Yangtze River, MCR-1 and NDM-1 were detected with higher abundance and antibiotic tolerance than the WWTP effluent and were significantly affected by nearby water contamination and human activities. In the DWTP, MCR-1 and NDM-1 were detected with average values 5.56 × 10⁷ copies/L and 2.14 × 10⁵ copies/L in the influent. Their hosting bacteria were undetectable in the effluent, but the two SARGs were still persistent with 1.39 × 10⁷ copies/L and 6.29 × 10⁴ copies/L, and were greatly enriched in the sludge. Molecular ecological networks demonstrated wide hosting relationships between MCR-1/NDM-1 and bacteria community in the DWTP. Redundancy analysis found that MCR-1 positively correlated with COD and NH₃-N, while negatively correlated with turbidity. Additionally, MCR-1 hosting bacteria positively correlated with NO₃^--N and negatively correlated with COD and NH₃-N. NDM-1 positively correlated with turbidity and NDM-1 hosting bacteria positively correlated with COD and NO₂^--N. The study demonstrated that the WWTP could not effectively remove SARGs with high amount of them being discharged into the Yangtze River. Then they were transported into the DWTP and the persistent SARGs in the effluent would probably be transferred into human, thus imposing great threats on public health.

High prevalence and dissemination of β-lactamase genes in swine farms in northern China

β-Lactamase (extended-spectrum β-lactamase (ESBL)/AmpC/carbapenemase)-encoding genes, primarily discovered in clinical settings, are increasingly recovering from the environment, thus posing potential threats to public health. This paper addresses the occurrence of high-risk β-lactamase genes (bla genes) in Chinese swine farm and its surrounding farmland, and investigated their seasonal variation and fate in piggery wastewater treatment system (PWWTS) using real-time quantitative PCR. It is observed that bla_TEM-1, bla_GES-1,bla_OXA-1 and bla_AmpC were the dominant bla genes in swine farms, which were present in all pig feces, and prevailed through each treatment stage of PWWTSs. Furthermore, bla genes were more abundant in winter than that in summer, with 0.01-1.65 logs variation in swine wastewater. Troublesomely, significant bla gene levels were still discharged via the final effluents (up to 10⁶ copies/mL) into farmland, resulting in the increase of bla gene abundance in soil (approximately 1-3 orders of magnitude). The discharge of bla genes in wastewater from swine farm highlights the need to mitigate the persistence and spreading of these elevated bla genes in agricultural systems.

Phenotypic and Genotypic Characterization of ESBL-, AmpC-, and Carbapenemase-Producing Klebsiella pneumoniae and Escherichia coli Isolates

OBJECTIVES

Drug resistance among gram-negative bacteria is a worldwide challenge. Due to the importance of drug-resistant Klebsiella pneumoniae and Escherichia coli strains in hospital-acquired infections, we aimed to determine the phenotypic and genotypic characteristics of ESBL-, AmpC-, and carbapenemase-producing isolates obtained from hospitalized patients in Tehran and Ilam (Iran).

MATERIALS AND METHODS

In total, 90 K. pneumoniae isolates and 65 E. coli isolates were collected from various infections. Phenotypic identification of bacterial isolates was performed using standard methods. Phenotypic screening of ESBL, AmpC, and carbapenemase enzymes was carried out. Detection of ESBL, AmpC, and carbapenemase genes was also performed by the PCR method.

RESULTS

Phenotypic detection tests showed that 36 (40%) K. pneumoniae and 23 (35.4%) E. coli isolates were ESBL producers. Moreover, 18 (20%) and 6 (9.2%) K. pneumoniae and E. coli isolates were AmpC producers, respectively. Modified Hodge test results indicated that 39 (43.3%) K. pneumoniae and 18 (27.7%) E. coli isolates produced carbapenemase. Molecular tests showed that 40% of K. pneumoniae and 36.9% of E. coli isolates were ESBL positive. AmpC was detected in 24.4 and 13.8% of K. pneumoniae and E. coli isolates. Carbapenemase was detected in 34 (37.8%) K. pneumoniae and 13 (20%) E. coli isolates. -Conclusion: In this study, 3 K. pneumoniae isolates simultaneously carried ESBL, AmpC, and carbapenemase genes. Up-to-date strategies such as combination therapy or utilization of new antimicrobial agents might help to combat such drug-resistant organisms.

Rapid detection of carbapenemases directly from positive blood cultures by the β-CARBA test

The rapid detection of blood stream infections (BSI) by carbapenemase-producing Enterobacterales (CPE) is indispensable to early optimize antibiotic treatment and to improve survival. While phenotypic tests are time-consuming and PCR is expensive and not available in many routine laboratories, colorimetric tests (e.g., Carba NP test) can provide rapid results at moderate cost. However, up to now, the detection of CPE-BSI requires a further 3-h incubation in broth supplemented with zinc sulfate and imipenem after a blood culture has become positive, thereby causing delay and additional hands-on time. The purpose of this study was to develop and evaluate a new method for the detection of CPE directly from positive blood culture without the need for incubation in broth, based on the commercially available colorimetric β-CARBA test. For the evaluation, blood cultures spiked with 140 different Enterobacterales isolates producing diverse beta-lactamases were tested with the new method. Of these, 70 were CPE (OXA-48-like, NDM, KPC, VIM, and GIM). After blood cultures turned positive, blood culture fluid was drawn, and erythrocytes were hemolyzed with SDS, washed, and equilibrated before the β-CARBA was performed on the bacterial pellet. All carbapenemases were reliably detected, including weak carbapenemases of the OXA-48 group. The sensitivity was 100% (95% CI 94.9-100) and the specificity 94.3% (95% CI 89.2-99.4). The time to result was 20 to 45 min. Carbapenemases can rapidly and reliably be detected directly from blood cultures using the new method, which could help to improve the outcome of these difficult-to-treat infections.

Carbapenem-resistant Gram-negative bacteria associated with catheter-related bloodstream infections in three intensive care units in Egypt

We aimed to identify the carbapenem-resistant Gram-negative bacteria (GNB) causing catheter-related bloodstream infections (CRBSI) in intensive care units (ICU) in a tertiary care Egyptian hospital, to study their resistance mechanisms by phenotypic and genetic tests, and to use ERIC-PCR for assessing their relatedness. The study was conducted over 2 years in three ICUs in a tertiary care hospital in Egypt during 2015-2016. We identified 194 bloodstream infections (BSIs); 130 (67.01%) were caused by GNB, of which 57 were isolated from CRBSI patients (73.84%). Identification of isolates was performed using conventional methods and MALDI-TOF MS. Antimicrobial susceptibility testing (AST) was done by disc diffusion following CLSI guidelines. Phenotypic detection of carbapenemases enzymes activity was by modified Hodge test and the Carba-NP method. Isolates were investigated for the most common carbapenemases encoding genes bla_KPC, bla_NDM, and bla_OXA-48 using multiplex PCR. Molecular typing of carbapenem-resistant isolates was done by ERIC-PCR followed by sequencing of common resistance genes. The overall rate of CRBSI in our study was 3.6 per 1000 central venous catheter (CVC) days. Among 57 Gram-negative CRBSI isolates, Klebsiella pneumoniae (K. pneumoniae) was the most frequently isolated (27/57; 47.4%), of which more than 70% were resistant to Meropenem. Phenotypic tests for carbapenemases showed that 37.9% of isolates were positive by modified Hodge test and 63.8% by Carba-NP detection. Multiplex PCR assay detected the bla_NDM in 28.6% of the isolates and bla_KPC in 26.8%, bla_NDM and bla_KPC were detected together in the same isolate in 5.6%, while bla_OXA-48-like were not detected. ERIC-PCR detected limited genetic relatedness between K. pneumoniae isolates. Elevated resistance rates were observed to all antibiotics including carbapenems among K. pneumoniae isolates causing CRBSI. ERIC-PCR showed that the resistant isolates were mainly polyclonal. Our results call for reinforcement of antimicrobial stewardship and measures to prevent CRBSI.

The prevalence and diversity of AmpC β-lactamase genes in plasmids from aquatic systems

This study aimed to investigate the presence and diversity of AmpC β-lactamase and integrase genes among DNA (genomic and plasmid) from bacterial populations in selected aquatic systems. Following an enrichment step, DNA was isolated and subjected to polymerase chain reaction (PCR) and digital droplet PCR. The intI1 gene and AmpC β-lactamase genes were present in genomic and plasmid DNA from all sites in the Mooi, Crocodile and Marico Rivers, with the exception of intI1 in the Marico River. Digital droplet PCR demonstrated that copy numbers varied considerably (0.0 to 29.38 copies per picogram of DNA). Some samples in which ampC was not detected, intI1 was present. Amplicons of ampC genes were subjected to restriction digest using HindIII. Samples where the restriction markers were absent were purified by cloning followed by plasmid extraction, PCR amplification, and sequencing of individual AmpC gene fragments. Phylogenetic analysis identified all positive AmpC genes as Class C β-lactamases, comprising of ampC, CMY- and ACT-families. Detecting AmpC and intl1 genes on plasmids suggests a high risk of horizontal gene transfer and potential dissemination of these and other antibiotic resistance genes surrounding immediate aquatic environments. Consequences of β-lactamase diversity in aquatic ecosystems are relatively unexplored in South African aquatic ecosystems.