Molecular characterization and prevalence of β-lactamase-producing Enterobacterales in livestock and poultry slaughterhouses wastewater in Iran

Beta-lactamase-producing Enterobacterales bacteria cause severe hard-to-treat infections. Currently, they are spreading beyond hospitals and becoming a serious global health concern. This study investigated the prevalence and molecular characterization of extended-spectrum β-lactamase and AmpC-type β-lactamase-producing Enterobacterales (ESBL-PE, AmpC-PE) in wastewater from livestock and poultry slaughterhouses in Ardabil, Iran. A total of 80 Enterobacterales bacteria belonging to 9 species were identified. Among the isolates, Escherichia coli (n = 21/80; 26.2%) and Citrobacter spp. (n = 18/80; 22.5%) exhibited the highest frequency. Overall, 18.7% (n = 15/80) and 2.5% (n = 2/80) of Enterobacterales were found to be ESBL and AmpC producers, respectively. The most common ESBL producer isolates were E. coli (n = 9/21; 42.8%) and Klebsiella pneumoniae (n = 6/7; 85.7%). All AmpC-PE isolates belonged to E. coli strains (n = 2/21; 9.5%). In this study, 80% of ESBL-PE and 100% of AmpC-PE isolates were recovered from poultry slaughterhouse wastewater. All ESBL-PE and AmpC-PE isolates were multidrug-resistant. In total, 93.3% of ESBL-PE isolates harbored the blaCTX-M gene, with the blaCTX-M-15 being the most common subgroup. The emergence of ESBL-PE and AmpC-PE in wastewater of food-producing animals allows for zoonotic transmission to humans through contaminated food products and contaminations of the environment.

Pharmacokinetic and Pharmacodynamic Analysis of the Oxacephem Antibiotic Flomoxef against Extended-Spectrum β-Lactamase-Producing Enterobacterales from Dogs

Flomoxef (FMX) may be a potential alternative to carbapenems for dogs infected with Enterobacterales-producing extended-spectrum β-lactamase (ESBL-E). However, the appropriate dosage of FMX in dogs with ESBL-E infections has yet to be established. This study was carried out to establish appropriate treatment regimens for FMX against ESBL-E infections in dogs using a pharmacokinetics-pharmacodynamics (PK-PD) approach. Five dogs were intravenously administered at a bolus dose of FMX (40 mg/kg body weight). Serum concentrations of FMX were calculated with high-performance liquid chromatography-tandem mass spectrometry, and then applied to determine PK indices based on a non-compartmental model. The cumulative fraction of response (CFR) was estimated based on the dissemination of minimum inhibitory concentrations among wild-type ESBL-E from companion animals. From the results, the dosage regimens of 40 mg/kg every 6 and 8 h were estimated to attain a CFR of >90% for wild-type isolates of ESBL-producing Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis for dogs. By contrast, all regimens had a CFR of <80% for ESBL-producing Enterobacter cloacae. Our results indicated that dosage regimens of 40 mg/kg FMX every 6 and 8 h can be a non-carbapenem treatment for canine infections of ESBL-producing Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis, but not for those of ESBL-producing Enterobacter cloacae.

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.

The risk factors, antimicrobial resistance patterns, and outcomes associated with extended-spectrum β-lactamases-Producing pathogens in pediatric urinary tract infection

BACKGROUND

Extended-spectrum β-lactamases-producing Escherichia coli, Klebsiella pneumoniae, and Proteus mirabilis (ESBL-producing-EKP) are an increasingly common cause of childhood urinary tract infection (UTI) worldwide. Recognizing the risk factors and antimicrobial resistance patterns may guide new management in this population.

METHODS

This is a retrospective cohort study of over 5 years in Taiwan (2017-2021). Inclusion criteria are hospitalized pediatric patients with the discharge diagnosis of UTI caused by E. coli, Klebsiella pneumoniae, or Proteus mirabilis. ESBL-producing-EKP and non-ESBL-producing-EKP UTI cases were reviewed for characteristics, urinary isolate antibiotics resistance, and clinical outcomes.

RESULTS

The incidence rate of ESBL-producing-EKP UTI increased over the study period (Overall incidence rate: 14.1 %, 46/327 patients). Recent antibiotic therapy in ≤6 months (X2 = 11.83, p < 0.01) and a preterm gestational history (X2 = 8.11, p < 0.05) were associated with an increased risk. The proportion of patients with these two risk factors for ESBL acquisition were 37.5 % (X2 = 9.08, p < 0.05). The co-resistance rate of ESBL-producing-EKP to other antimicrobial agents was 63.0 % for gentamicin, 56.5 % for trimethoprim-sulfamethoxazole, 52.2 % for ciprofloxacin, 4.3 % for amikacin, and 2.2 % for imipenem. The generalized linear model analysis identified a significantly longer length of stay (β: 2.85; 95 % confidence interval [CI]: 1.14-4.56; p < 0.01) and intensive care unit duration (β: 5.86; 95 % CI: 1.59-10.12; p < 0.01) among patients with ESBL-producing-EKP UTI.

CONCLUSION

Amikacin should be considered as an alternative antimicrobial choice beyond carbapenems for ESBL-producing-EKP UTI, especially in the context of carbapenem-resistant E. coli/Klebsiella pneumoniae (CRE/CRKP) emergence.

Culture-Independent Multiplexed Detection of Drug-Resistant Bacteria Using Surface-Enhanced Raman Scattering

The rapid and accurate detection of bacteria resistance to β-lactam antibiotics is critical to inform optimal treatment and prevent overprescription of potent antibiotics. Here, we present a fast, culture-independent method for the detection of extended-spectrum β-lactamases (ESBLs) using surface-enhanced Raman scattering (SERS). The method uses Raman probes that release sulfur-based Raman active molecules in the presence of β-lactamases. The released thiol molecules can be captured by gold nanoparticles, leading to amplified Raman signals. A broad-spectrum cephalosporin probe R1G and an ESBL-specific probe R3G are designed to enable duplex detection of bacteria expressing broad-spectrum β-lactamases or ESBLs with a detection limit of 103 cfu/mL in 1 h incubation. Combined with a portable Raman microscope, our culturing-free SERS assay has reduced screening time to 1.5 h without compromising sensitivity and specificity.

Prevalence and Types of Extended-Spectrum β-Lactamase-Producing Bacteria in Retail Seafood

Objectives: To assess prevalence and types of extended-spectrum β-lactamase (ESBL)-producing bacteria in retail seafood. Methods: A literature review was completed according to international guidelines for systematic reviews, except for being performed by a single reviewer. Kruskal-Wallis and Dunn tests were used to determine statistical differences between continents or seafood types. Results: Among 12,277 hits, 42 publications from 2011 to 2023 were deemed relevant to the review's objectives. The median prevalence of ESBL-contaminated products was 19.4%. A significantly lower prevalence was observed in Europe (p = 0.006) and Africa (p = 0.004) compared to Asia. Amongst the 2053 isolates analyzed in the selected studies, 44.8% were ESBL-positive. The predominant type was CTX-M (93.6%), followed by TEM (6.7%) and SHV (5.0%). Only 32.6% and 18.5% of the CTX-M-positive isolates were typed to group and gene level, respectively. While group 1 (60.2%) was prevalent over group 9 (39.8%) among Enterobacterales, the opposite trend was observed in Vibrio spp. (60.0% vs. 40.0%). Information at gene level was limited to Enterobacterales, where CTX-M-15 was the most prevalent (79.2%). Conclusions: On average, one in five seafood products sold at retail globally is contaminated with ESBL-producing Enterobacterales of clinical relevance. Our findings highlight a potential risk for consumers of raw seafood, especially in Asia.

Extended-Spectrum β-Lactamase and Carbapenemase-Producing Gram-Negative Bacteria and Associated Factors Among Patients Suspected of Community and Hospital-Acquired Urinary Tract Infections at Ayder Comprehensive Specialized Hospital, Tigrai, Ethiopia

Background

Little is known about bacteria that produce extended-spectrum beta-lactamases (ESBLs) and carbapenemase in patients with urinary tract infections (UTIs) in Tigrai, Ethiopia. The aim of this study was to describe the magnitude of ESBL- and carbapenemase -producing gram-negative bacteria among patients suspected of community- and hospital-acquired UTIs at a referral hospital in Tigrai, Ethiopia.

Methods

A cross-sectional study was conducted at Ayder Comprehensive Specialized hospital from January 2020 to June 2020. A 10-20 mL sample of morning mid-stream and catheter urine was collected from consenting participants. Urine samples were cultured on cysteine lactose electrolyte deficient medium and MacConkey agar, and bacteria were identified using standard microbiological protocols. The Kirby-Bauer disk diffusion method was used for antimicrobial susceptibility testing. The combination disk and modified Hodge tests were used detect ESBL and carbapenemase production, respectively. The data was entered into EPI 3.1 software and analyzed using SPSS version 21.

Results

Overall, 67 gram-negative bacteria were recovered from 64 participants. Escherichia coli was the predominant isolate (68.6%), followed by Klebsiella pneumoniae (22.4%), while ESBL production was found in both Escherichia coli and Klebsiella pneumoniae (52.2% and 86.7%, respectively). Isolates recovered from patients with hospital-acquired UTIs were more likely to produce ESBLs (AOR= 16.2; 95% CI: 2.95-89.5). Carbapenemase was produced by 4.3% of E. coli and 20% of Klebsiella pneumoniae isolates. High resistance rates were found against tetracycline (84.8%), ampicillin (78.3%), amoxicillin/clavulanic acid (58.7%) for Escherichia coli isolates and against ampicillin (93.3%), sulphamethexazole trimethoprim (93.3%), cefotaxime (86.6%), and ceftazidime (86.6%), and tetracycline (73.3%) for Klebsiella pneumoniae.

Conclusion

Most UTIs were caused by ESBL-producing bacteria, especially those that were related to healthcare. Microbiological-based therapy for patients with UTIs is essential at our study site due to high rates of ESBL and significant carbapenemase production with concomitant high rates of drug resistance to several antibiotics.

Inverse Association between the Existence of CRISPR/Cas Systems with Antibiotic Resistance, Extended Spectrum β-Lactamase and Carbapenemase Production in Multidrug, Extensive Drug and Pandrug-Resistant Klebsiella pneumoniae

Antimicrobial resistance, with the production of extended-spectrum β-lactamases (ESBL) and carbapenemases, is common in the opportunistic pathogen, Klebsiella pneumoniae. This organism has a genome that can contain clustered regularly interspaced short palindromic repeats (CRISPRs), which operate as a defense mechanism against external invaders such as plasmids and viruses. This study aims to determine the association of the CRISPR/Cas systems with antibiotic resistance in K. pneumoniae isolates from Iraqi patients. A total of 100 K. pneumoniae isolates were collected and characterized according to their susceptibility to different antimicrobial agents. The CRISPR/Cas systems were detected via PCR. The phenotypic detection of ESBLs and carbapenemases was performed. The production of ESBL was detected in 71% of the isolates. Carbapenem-resistance was detected in 15% of the isolates, while only 14% were susceptible to all antimicrobial agents. Furthermore, the bacteria were classified into multidrug (77%), extensively drug-resistant (11.0%) and pandrug-resistant (4.0%). There was an inverse association between the presence of the CRISPR/Cas systems and antibiotic resistance, as resistance was higher in the absence of the CRISPR/Cas system. Multidrug resistance in ESBL-producing and carbapenem-resistant K. pneumoniae occurred more frequently in strains negative for the CRISPR/Cas system. Thus, we conclude that genes for exogenous antibiotic resistance can be acquired in the absence of the CRISPR/Cas modules that can protect the bacteria against acquiring foreign DNA.

QAC Resistance Genes in ESBL-Producing E. coli Isolated from Patients with Lower Respiratory Tract Infections in the Central Slovenia Region-A 21-Year Survey

Biocidal products prevent the spread of pathogenic microorganisms, including extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC), which is one of the most alarming health problems worldwide. Quaternary ammonium compounds (QACs) are surface-active agents that interact with the cytoplasmic membrane and are widely used in hospitals and food processing environments. A collection of 577 ESBL-EC, isolated from lower respiratory tract (LRT) samples, was screened for QAC resistance genes oqxA; oqxB; qacEΔ1; qacE; qacF/H/I; qacG; sugE (p); emrE; mdfA; sugE (c); ydgE; ydgF; and for class 1, 2, and 3 integrons. The prevalence of chromosome-encoded genes ranged from 77 to 100%, while the prevalence of QAC resistance genes encoded on mobile genetic elements (MGEs) was relatively low (0-0.9%), with the exception of qacEΔ1 (54.6%). PCR screening detected the presence of class 1 integrons in 36.3% (n = 210) of isolates, which were positively correlated with qacEΔ1. More correlations between QAC resistance genes, integrons, sequence type group ST131, and β-lactamase genes were presented. The results of our study confirm the presence of QAC resistance genes and also class 1 integrons commonly found in multidrug-resistant clinical isolates and highlight the potential role of QAC resistance genes in the selection of ESBL-producing E. coli in hospitals.

Prevalence and antimicrobial susceptibility of Acinetobacter spp. in a tertiary care hospital in Peshawar: a cross-sectional study

Acinetobacter spp. have been a primary cause of nosocomial infections worldwide, causing significant morbidity and mortality, especially in Pakistan. The purpose of this study was to investigate the trend of antimicrobial resistance over a 5-year period in a tertiary care hospital in Pakistan.

Methods

A retrospective cross-sectional study regarding the occurrence and antimicrobial resistance of Acinetobacter spp. recovered from clinical specimens that were referred to the Pathology Laboratory of Northwest General Hospital, Peshawar. The data from 2014 to 2019 was recorded and analyzed by the laboratory. Sociodemographic characteristics and laboratory record data was analyzed using SPSS, version 25. A chi-square test was applied to see the significance.

Results

Of 59 483 clinical samples, Acinetobacter baumannii strains were detected in 114 of them. The majority of the clinical samples were from blood (89.5%) followed by sputum (7.9%), wound swab (1.8%), and bone marrow (0.9%). A. baumannii has been found in 52 men (67.53%) and 28 women (75.67%), with an overall risk of 0.669 times. In 76 men (98.70%), sensitivity for ertapenem (99.1), colistin (96.49), and tigecycline (78.9%) were also observed which indicated the potential viability of these drugs to treat multidrug-resistant (MDR) Acinetobacter infections. The male-to-female risk ratio was 0.98 for colistin and 0.71 for amikacin.

Conclusion

Increased frequency of MDR supports the need for continuous surveillance to determine the prevalence and evolution of MDR Acinetobacter spp. in Pakistan. Colistin, tigecyclines, and ertapenem remain the possible line of drugs to treat MDR Acinetobacter.

Genomic Characterization of Uropathogenic Escherichia coli Isolates from Tertiary Hospitals in Riyadh, Saudi Arabia

Uropathogenic Escherichia coli (UPEC) is the most common cause of urinary tract infections (UTIs) in hospitalised and non-hospitalised patients. Genomic analysis was used to gain further insight into the molecular characteristics of UPEC isolates from Saudi Arabia. A total of 165 isolates were collected from patients with UTIs between May 2019 and September 2020 from two tertiary hospitals in Riyadh, Saudi Arabia. Identification and antimicrobial susceptibility testing (AST) were performed using the VITEK system. Extended-spectrum β-lactamase (ESBL)-producing isolates (n = 48) were selected for whole genome sequencing (WGS) analysis. In silico analysis revealed that the most common sequence types detected were ST131 (39.6%), ST1193 (12.5%), ST73 (10.4%), and ST10 (8.3%). Our finding showed that blaCTX-M-15 gene was detected in the majority of ESBL isolates (79.2%), followed by blaCTX-M-27 (12.5%) and blaCTX-M-8 (2.1%). ST131 carried blaCTX-M-15 or blaCTX-M-27, and all ST73 and ST1193 carried blaCTX-M-15. The relatively high proportion of ST1193 in this study was notable as a newly emerged lineage in the region, which warrants further monitoring.

Molecular characterization of the whole genome in clinical multidrug-resistant strains of Klebsiella pneumoniae

INTRODUCTION

Antimicrobial resistance (AMR) is a major public health concern. The spread of AMR-encoding genes between enterobacteria, especially in Klebsiella pneumoniae strains, lead to failure in the treatment of most individuals. The aim of this study was to characterize multi-drug resistant (MDR) clinical K. pneumoniae isolates that produce extended-spectrum β-lactamases (ESBLs) from Algeria.

METHODOLOGY

The isolates were identified using biochemical tests, and the identification was confirmed by mass spectrometry using VITEK® MS (BioMerieux, Marcy l'Etoile, France). Antibiotic susceptibility testing was assessed by the disk diffusion method. Molecular characterization was performed by whole genome sequencing (WGS) using Illumina technology. Sequenced raw reads were processed using bioinformatics parameters: FastQC, ARIBA, and Shovill-Spades. Multilocus sequence typing (MLST) was used to estimate the evolutionary relationship between isolate strains.

RESULTS

Molecular analysis resulted in the first detection of blaNDM-5 encoding K. pneumoniae in Algeria. Other resistance genes were blaTEM, blaSHV, blaCTX-M, aac(6')-Ib-cr, qnrB1, qnrB4, qnrB19, qnrS1, gyrA and parC variants.

CONCLUSIONS

Our data demonstrated a very high level of resistance in clinical K. pneumoniae strains which were resistant to most common antibiotic families. This was the first detection of K. pneumoniae with the blaNDM-5 gene in Algeria. Surveillance of antibiotic use and measures for control should be implemented to reduce occurrence of AMR in clinical bacteria.

Colonization with extended-spectrum beta-lactamase-producing Enterobacteriaceae in unaccompanied refugee minors on arrival in France

In a prospective observational study, we recorded that 25.7% of 139 unaccompanied migrant minors arriving in Angers, Western France were colonized with extended-spectrum β-lactamase producing Enterobacteriaceae (ESBL-PE). Concurrently, we highlighted that some minors had acquired ESBL-PE after their arrival in France.

Causative agents of bloodstream infections in two Croatian hospitals and their resistance mechanisms

Blood samples were collected alongside with routine blood cultures (BC) from patients with suspected sepsis, to evaluate the prevalence of different causative agents in patients with bacteraemia. Among 667 blood samples, there were 122 positive BC (18%). Haemoglobin content, platelet number, and systolic blood pressure values were significantly lower in patients with positive BC, whereas serum lactate levels, CRP, creatinine and urea content were significantly higher in patients with positive BC. The rate of multidrug (MDR) or extensively drug resistant (XDR) bacteria was 24% (n = 29): Klebsiella pneumoniae (9), Pseudomonas aeruginosa (9), Acinetobacter baumannii (4), Escherichia coli (1), vancomycin resistant Enterococcus spp (VRE) (3), and methicillin-resistant Staphylococcus aureus MRSA (3). The dominant resistance mechanisms were the production of extended-spectrum β-lactamases, OXA-48 carbapenemase, and colistin resistance in K. pneumoniae, VIM metallo-β-lactamases in P. aeruginosa and OXA-23-like oxacillinases in A. baumannii. The study revealed high rate of MDR strains among positive BCs in Zagreb, Croatia.

One Health Genomic Analysis of Extended-Spectrum β-Lactamase‒Producing Salmonella enterica, Canada, 2012‒2016

Extended-spectrum β-lactamases (ESBLs) confer resistance to extended-spectrum cephalosporins, a major class of clinical antimicrobial drugs. We used genomic analysis to investigate whether domestic food animals, retail meat, and pets were reservoirs of ESBL-producing Salmonella for human infection in Canada. Of 30,303 Salmonella isolates tested during 2012–2016, we detected 95 ESBL producers. ESBL serotypes and alleles were mostly different between humans (n = 54) and animals/meat (n = 41). Two exceptions were bla_SHV-2 and bla_CTX-M-1 IncI1 plasmids_, which were found in both sources. A subclade of S. enterica serovar Heidelberg isolates carrying the same IncI1-bla_SHV-2 plasmid differed by only 1–7 single nucleotide variants. The most common ESBL producer in humans was Salmonella Infantis carrying bla_CTX-M-65, which has since emerged in poultry in other countries. There were few instances of similar isolates and plasmids, suggesting that domestic animals and retail meat might have been minor reservoirs of ESBL-producing Salmonella for human infection.

Prevalence and Molecular Characterisation of Extended-Spectrum Beta-Lactamase-Producing Shiga Toxin-Producing Escherichia coli, from Cattle Farm to Aquatic Environments

Extended-spectrum beta-lactamase (ESBL)-producing bacteria are a major problem for public health worldwide because of limited treatment options. Currently, only limited information is available on ESBL-producing Shiga toxin-producing Escherichia coli (STEC) in cattle farms and the surrounding aquatic environment. This study sought to track and characterise ESBL-producing STEC disseminating from a cattle farm into the water environment. Animal husbandry soil (HS), animal manure (AM), animal drinking water (ADW), and nearby river water (NRW) samples were collected from the cattle farm. Presumptive ESBL-producing STEC were isolated and identified using chromogenic media and mass spectrophotometry methods (MALDI-TOF-MS), respectively. The isolates were subjected to molecular analysis, and all confirmed ESBL-producing STEC isolates were serotyped for their O serogroups and assessed for antibiotic resistance genes (ARGs) and for the presence of selected virulence factors (VFs). A phylogenetic tree based on the multilocus sequences was constructed to determine the relatedness among isolates of ESBL-producing STEC. The highest prevalence of ESBL-producing STEC of 83.33% was observed in HS, followed by ADW with 75%, NRW with 68.75%, and the lowest was observed in AM with 64.58%. Out of 40 randomly selected isolates, 88% (n = 35) belonged to the serogroup O45 and 13% (n = 5) to the serogroup O145. The multilocus sequence typing (MLST) analysis revealed four different sequence types (STs), namely ST10, ST23, ST165, and ST117, and the predominant ST was found to be ST10. All 40 isolates carried sul1 (100%), while bla_OXA, bla_CTX-M, sul2, bla_TEM, and qnrS genes were found in 98%, 93%, 90%, 83%, and 23% of the 40 isolates, respectively. For VFs, only stx2 was detected in ESBL-producing STEC isolates. The results of the present study indicated that a cattle environment is a potential reservoir of ESBL-producing STEC, which may disseminate into the aquatic environment through agricultural runoff, thus polluting water sources. Therefore, continual surveillance of ESBL-producing STEC non-O157 would be beneficial for controlling and preventing STEC-related illnesses originating from livestock environments.

The occurrence of antibiotic-resistant bacteria on the clothes of nursery teachers in daycare centres

AIMS

Childcare facilities act as microenvironments that facilitate and promote the selection, spread, and transmission of antibiotic-resistant microorganisms in the community. We focused on the study of antimicrobial resistance and genetic predispositions for β-lactamase production in bacterial isolates from nursery teachers' clothing.

METHODS AND RESULTS

Antimicrobial resistance of bacterial strains belonging to Enterobacteriaceae, Enterococcus, Staphylococcus spp., Pseudomonas spp. and Bacillus spp. isolated from 80 samples of nursery teachers' clothing was determined. The selected ESβL genes were found in 30 (44.1%) of 68 strains examined. The CTX-M type ESβL determinants were detected in 15.4%, 71.5%, and 42.5% of the Enterobacteriaceae, Pseudomonas, and Bacillus isolates, respectively. The OXA-type coding genes were detected only in strains of the genera Pseudomonas (57.1%) and Bacillus (48.6%). Thus, most B. cereus strains were sensitive to the recommended antibiotics used to treat infections caused by these bacteria. Methicillin resistance was phenotypically confirmed in 27 (14.6%) of 185 staphylococcal isolates. Four isolates (2.2%) were identified as MRSA. Vancomycin resistance was not observed in any of the staphylococcal and enterococci strains.

CONCLUSIONS

This study has shown that potential pathogens have been isolated from the clothing of nursery teachers, posing a risk of transmission to children. These clothes should be maintained and properly laundered to avoid cross-contamination and the spread of multidrug-resistant (MDR) bacteria in childcare centres.

SIGNIFICANCE AND IMPACT OF THE STUDY

This study provides insight into the route of transmission of MDR microorganisms through the clothing of nursery teachers, to which greater importance should be given in the future. Proper procedures for the cleaning and use of clothing in daycare centres should be clarified and standardised.

Impact of Peptidoglycan Recycling Blockade and Expression of Horizontally Acquired β-Lactamases on Pseudomonas aeruginosa Virulence

In the current scenario of antibiotic resistance magnification, new weapons against top nosocomial pathogens like Pseudomonas aeruginosa are urgently needed. The interplay between β-lactam resistance and virulence is considered a promising source of targets to be attacked by antivirulence therapies, and in this regard, we previously showed that a peptidoglycan recycling blockade dramatically attenuated the pathogenic power of P. aeruginosa strains hyperproducing the chromosomal β-lactamase AmpC. Here, we sought to ascertain whether this observation could be applicable to other β-lactamases. To do so, P. aeruginosa wild-type or peptidoglycan recycling-defective strains (ΔampG and ΔnagZ) harboring different cloned β-lactamases (transferable GES, VIM, and OXA types) were used to assess their virulence in Galleria mellonella larvae by determining 50% lethal doses (LD50s). A mild yet significant LD50 increase was observed after peptidoglycan recycling disruption per se, whereas the expression of class A and B enzymes did not impact virulence. While the production of the narrow-spectrum class D OXA-2 entailed a slight attenuation, its extended-spectrum derivatives OXA-226 (W159R [bearing a change of W to R at position 159]), OXA-161 (N148D), and principally, OXA-539 (D149 duplication) were associated with outstanding virulence impairments, especially in recycling-defective backgrounds (with some LD50s being >1,000-fold that of the wild type). Although their exact molecular bases remain to be deciphered, these results suggest that mutations affecting the catalytic center and, therefore, the hydrolytic spectrum of OXA-2-derived enzymes also drastically impact the pathogenic power of P. aeruginosa. This work provides new and relevant knowledge to the complex topic of the interplay between the production of β-lactamases and virulence that could be useful to build future therapeutic strategies against P. aeruginosa. IMPORTANCE Pseudomonas aeruginosa is one of the leading nosocomial pathogens whose growing resistance makes the development of therapeutic options extremely urgent. The resistance-virulence interplay has classically aroused researchers' interest as a source of therapeutic targets. In this regard, we describe a wide array of virulence attenuations associated with different transferable β-lactamases, among which the production of OXA-2-derived extended-spectrum β-lactamases stood out as a dramatic handicap for pathogenesis, likely as a side effect of mutations causing the expansion of their hydrolytic spectrums. Moreover, our results confirm the validity of disturbing peptidoglycan recycling as a weapon to attenuate P. aeruginosa virulence in class C and D β-lactamase production backgrounds. In the current scenario of dissemination of horizontally acquired β-lactamases, this work brings out new data on the complex interplay between the production of specific enzymes and virulence attenuation that, if complemented with the characterization of the underlying mechanisms, will likely be exploitable to develop future virulence-targeting antipseudomonal strategies.

Controversies in the management of ESBL-producing Enterabacterales. Clinical Implications

Extended-spectrum β-lactamases (ESBL)-producing organisms currently represent a major health problem. Although recently published guidelines still consider carbapenems as the treatment of choice for ESBL-producing infections, it is necessary to find non-carbapenem β-lactams as alternatives to reduce the effects associated with their overutilization. In this review we focus on these alternatives to carbepenem use. It is possible that piperacillin-tazobactam may be an alternative in clinical settings with "low inoculum" infections like urinary tract infections. Newer β-lactam-β-lactamase inhibitors (BLBLIs) are potential options too. The current available data support the efficacy of both ceftazidime-avibactam and ceftolozane-tazobactam against susceptible ESBL-producing Enterobacterales (ESBL-E). We are waiting for the results of MERINO-3 study to confirm whether ceftolozane-tazobactam is a good option versus meropenem for treating bloodstream infections caused by ESBL- or AmpC-producing Enterobacterales.

IS1294 Reorganizes Plasmids in a Multidrug-Resistant Escherichia coli Strain

The aims of this study were to elucidate the role of IS1294 in plasmid reorganization and to analyze biological characteristics of cointegrates derived from different daughter plasmids. The genetic profiles of plasmids in Escherichia coli strain C21 and its transconjugants were characterized by conjugation, S1 nuclease pulsed-field gel electrophoresis (S1-PFGE), Southern hybridization, whole-genome sequencing (WGS) analysis, and PCR. The traits of cointegrates were characterized by conjugation and stability assays. blaCTX-M-55-bearing IncI2 pC21-1 and nonresistant IncI1 pC21-3, as conjugative helper plasmids, were fused with nonconjugative rmtB-bearing IncN-X1 pC21-2, generating cointegrates pC21-F1 and pC21-F2. Similarly, pC21-1 and pC21-3 were fused with nonconjugative IncF33:A-:B- pHB37-2 from another E. coli strain to generate cointegrates pC21-F3 and pC21-F4 under experimental conditions. Four cointegrates were further conjugated into the E. coli strain J53 recipient at high conjugation frequencies, ranging from 2.8 × 10-3 to 3.2 × 10-2. The formation of pC21-F1 and pC21-F4 was the result of host- and IS1294-mediated reactions and occurred at high fusion frequencies of 9.9 × 10-4 and 2.1 × 10-4, respectively. Knockout of RecA resulted in a 100-fold decrease in the frequency of plasmid reorganization. The phenomenon of cointegrate pC21-F2 and its daughter plasmids coexisting in transconjugants was detected for the first time in plasmid stability experiments. IS26-orf-oqxAB was excised from cointegrate pC21-F2 through a circular intermediate at a very low frequency, which was experimentally observed. To the best of our knowledge, this is the first report of IS1294-mediated fusion between plasmids with different replicons. This study provides insight into the formation and evolution of cointegrate plasmids under different drug selection pressures, which can promote the dissemination of MDR plasmids. IMPORTANCE The increasing resistance to β-lactams and aminoglycoside antibiotics, mainly due to extended-spectrum β-lactamases (ESBLs) and 16S rRNA methylase genes, is becoming a serious problem in Gram-negative bacteria. Plasmids, as the vehicles for resistance gene capture and horizontal gene transfer, serve a key role in terms of antibiotic resistance emergence and transmission. IS26, present in many antibiotic-resistant plasmids from Gram-negative bacteria, plays a critical role in the spread, clustering, and reorganization of resistance determinant-encoding plasmids and in plasmid reorganization through replicative transposition mechanisms and homologous recombination. However, the role of IS1294, present in many MDR plasmids, in the formation of cointegrates remains unclear. Here, we investigated experimentally the intermolecular recombination of IS1294, which occurred with high frequencies and led to the formation of conjugative MDR cointegrates and facilitated the cotransfer of blaCTX-M-55 and rmtB, and we further uncovered the significance of IS1294 in the formation of cointegrates and the common features of IS1294-driven cointegration of plasmids.

The role of tazobactam-based combinations for the management of infections due to extended-spectrum β-lactamase-producing Enterobacterales: Insights from the Society of Infectious Diseases Pharmacists

Extended-spectrum β-lactamase (ESBL)-producing Enterobacterales are a global threat to public health due to their antimicrobial resistance profile and, consequently, their limited available treatment options. Tazobactam is a sulfone β-lactamase inhibitor with in vitro inhibitory activity against common ESBLs in Enterobacterales, including CTX-M. However, the role of tazobactam-based combinations in treating infections caused by ESBL-producing Enterobacterales remains unclear. In the United States, two tazobactam-based combinations are available, piperacillin-tazobactam and ceftolozane-tazobactam. We evaluated and compared the roles of tazobactam-based combinations against ESBL-producing organisms with emphasis on pharmacokinetic/pharmacodynamic exposures in relation to MIC distributions and established breakpoints, clinical outcomes data specific to infection site, and considerations for downstream effects with these agents regarding antimicrobial resistance development. While limited data with ceftolozane-tazobactam are encouraging for its potential role in infections due to ESBL-producing Enterobacterales, further evidence is needed to determine its place in therapy. Conversely, currently available microbiologic, pharmacokinetic, pharmacodynamic, and clinical data do not suggest a role for piperacillin-tazobactam, and we caution clinicians against its usage for these infections.

Carriage Prevalence of Extended-Spectrum β-Lactamase Producing Enterobacterales in Outpatients Attending Community Health Centers in Blantyre, Malawi

Antimicrobial resistance due to extended-spectrum β-lactamase (ESBL) production by Enterobacterales is a global health problem contributing to increased morbidity and mortality, particularly in resource-constrained countries. We aimed to determine the prevalence of extended-spectrum β-lactamase-producing Enterobacterales (ESBL-E) in community patients in Blantyre, Malawi. Clinical samples were collected from 300 patients and screened for ESBL-E using a CHROMagar^TM ESBL medium. Confirmation of ESBL production was done by a combination disk test (CDT). The prevalence of community-acquired ESBL-E was 16.67% (50/300, 95% CI = 12.43–20.91%). The most common ESBL-E species isolated was Escherichia coli (66%). All ESBL-E isolates were resistant to Trimethoprim-Sulfamethoxazole except for 2% of E. coli. Besides this, all ESBL-E were susceptible to Imipenem and only 4% were resistant to Meropenem. No patients with a positive ESBL-E phenotype had a history of hospital admission in the last three months, and the carriage of ESBL-E was neither associated with the demographic nor the clinical characteristics of participants. Our findings reveal a low presence of ESBL-E phenotypes in community patients. The low prevalence of ESBL-E in the community settings of Blantyre can be maintained if strong infection and antimicrobial use-control strategies are implemented.

Virulence, Antimicrobial Resistance and Biofilm Production of Escherichia coli Isolates from Healthy Broiler Chickens in Western Algeria

The aim of this study was to assess the virulence, antimicrobial resistance and biofilm production of Escherichia coli strains isolated from healthy broiler chickens in Western Algeria. E. coli strains (n = 18) were identified by matrix-assisted laser desorption-ionization time-of-flight mass spectrometry. Susceptibility to 10 antibiotics was determined by standard methods. Virulence and extended-spectrum β-lactamase (ESBL) genes were detected by PCR. The biofilm production was evaluated by microplate assay. All the isolates were negative for the major virulence/toxin genes tested (rfbE, fliC, eaeA, stx1), except one was stx2-positive. However, all were resistant to at least three antibiotics. Ten strains were ESBL-positive. Seven carried the β-lactamase bla_TEM gene only and two co-harbored bla_TEM and bla_CTX-M-1 genes. One carried the bla_SHV gene. Among the seven strains harboring bla_TEM only, six had putative enteroaggregative genes. Two contained irp2, two contained both irp2 and astA, one contained astA and another contained aggR, astA and irp2 genes. All isolates carrying ESBL genes were non-biofilm producers, except one weak producer. The ESBL-negative isolates were moderate biofilm producers and, among them, two harbored astA, two irp2, and one aggR, astA and irp2 genes. This study highlights the spread of antimicrobial-resistant E. coli strains from healthy broiler chickens in Western Algeria.

Detection of CTX-M-27 β-Lactamase Genes on Two Distinct Plasmid Types in ST38 Escherichia coli from Three U.S. States

Infections caused by extended-spectrum-β-lactamase (ESBL)-producing Escherichia coli are a significant cause of morbidity and health care costs. Globally, the prevailing clonal type is ST131 in association with the bla_CTX-M-15 β-lactamase gene. However, other ESBLs, such as bla_CTX-M-14 and bla_CTX-M-27, can also be prevalent in some regions. We identified ST38 ESBL-producing E. coli from different regions in the United States which carry bla_CTX-M-27 embedded on two distinct plasmid types, suggesting the potential emergence of new ESBL lineages.

A Rapid Antimicrobial Susceptibility Test for Klebsiella pneumoniae Using a Broth Micro-Dilution Combined with MALDI TOF MS

Background

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) is a novel method that can be used to identify pathogens and has potential applications in the detection of drug-resistant bacteria.

Purpose

To evaluate the ability of a MALDI-TOF MS-based broth micro-dilution method in detecting the minimum inhibitory concentration (MIC) values of Klebsiella pneumoniae to ceftriaxone and imipenem.

Materials and Methods

Sixty strains of K. pneumoniae with different levels of resistance to carbapenems and cephalosporins were randomly collected. The 0.5 McFarland (Mc) concentration of the bacterial suspension was inoculated in cation-adjusted Mueller-Hinton broth (CAMHB) with a final cell turbidity of 5×10⁵ CFU/mL. The broth was incubated with serial concentrations of antibiotics. After centrifuging the bacterial suspensions, the lysed cells were analyzed by MALDI-TOF MS to identify the growth-promoting or inhibitory effects on K. pneumoniae. The molecular mechanisms of resistance were investigated by PCR and DNA sequencing analysis.

Results

The expression of known resistance genes (blaKPC, blaFOX, blaDHA, blaCTX-M and blaTEM) was detected in the 30 carbapenems-resistant strains. The agreement between the MIC values derived from the MALDI-TOF MS analysis and from the broth micro-dilution method was 61.7% for ceftriaxone and 71.7% for imipenem. According to the Clinical and Laboratory Standards Institute (CLSI) breakpoint of resistance to ceftriaxone and imipenem, the 60 isolates were accurately classified as resistant or susceptible isolates with 100% sensitivity and 100% specificity.

Conclusion

The transmission and infection of multidrug-resistant bacteria could be better managed and treated with the rapid identification of strains and antimicrobial susceptibility. A MALDI-TOF MS-based susceptibility test could be used to identify resistance of K. pneumoniae within a short time-frame. This approach could potentially be used as a supplementary antimicrobial susceptibility test that could be investigated on more bacterial species combined with different antibiotics.

Prophylactic application of antibiotics selects extended-spectrum β-lactamase and carbapenemases producing Gram-negative bacteria in the oral cavity

Prophylactic administration of broad-spectrum antibiotics in surgery can change the oral microbiome and induce colonization of oral cavity with Gram-negative bacteria including multidrug (MDR) or extensively drug resistant (XDR) organisms which can lead to lower respiratory tract infections. The aim of the study was to analyse the Gram-negative isolates obtained from oral cavity of the mechanically ventilated patients in ICUs, after prophylactic application of antibiotics and their resistance mechanisms and to compare them with the isolates obtained from tracheal aspirates from the same patients. The antibiotic susceptibility was determined by broth dilution method. PCR was applied to detect genes encoding β-lactamases. Marked diversity of Gram-negative bacteria and resistance mechanisms was found. High resistance rates and high rate of bla_CTX-M and carbapenemase encoding genes (bla_VIM-1 , bla_OXA-48 ) were found among Klebsiella pneumoniae. Pseudomonas aeruginosa was found to harbour bla_VIM and in one strain bla_PER-1 gene, whereas Acinetobacter baumannii produced OXA-23-like and OXA-24/40-like oxacillinases and was XDR in all except one case. All XDR isolates belong to international clonal lineage II (IC II). The main finding of the study is that the prophlylactic application of antibiotics in surgery intensive care units (ICUs) is associated with the colonization of oral cavity and lower respiratory tract with Gram-negative bacteria. The identity of Gram-negative bacteria in oral cavity reflected those found in endotracheal aspirates leading to conclusion that oral swab as non-invasive specimen can predict the colonization of lower respiratory tract with resistant Gram-negative organisms and the risk for development of ventilator-associated pneumonia.

Characterization of Extended-Spectrum β-Lactamase-Producing and AmpC β-Lactamase-Producing Enterobacterales Isolated from Companion Animals in Korea

The emergence of extended-spectrum cephalosporin (ESC)-resistant Gram-negative bacteria is of great concern in both human and veterinary medicine. The aim of this study was to investigate ESC-resistant bacterial isolates from companion animals in South Korea between 2017 and 2019. Isolates with ESC resistance genes, which were identified by PCR, were assessed for genetic relatedness by multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE). In total, 91 ESC-resistant Escherichia coli, Klebsiella spp., Serratia spp., and Enterobacter cloacae isolates harbored the bla_TEM gene. Among other ESC resistance genes, bla_CTX-M-15, bla_CIT, and bla_CTX-M-55 were predominantly detected in E. coli isolates, whereas bla_SHV and bla_DHA were more frequently detected in Klebsiella pneumoniae isolates. In addition, all bla_EBC-positive isolates were classified as E. cloacae. From the MLST results, bla_CTX-M-9-carrying ST131, bla_CIT-carrying ST405, and bla_CTX-M-1-carrying ST3285 strains were dominant among E. coli isolates. ST273 and ST275 strains harboring bla_SHV were frequently detected in K. pneumoniae isolates. Various sequence types were obtained in E. cloacae and Klebsiella oxytoca isolates. All isolates demonstrated unique PFGE profiles (<57–98% similarity) and were unlikely to be derived from a single clone. The present study reveals the presence and wide genetic distribution of ESC-resistant bacterial species in South Korean companion animals.

Epidemiology and Characterization of CTX-M-55-Type Extended-Spectrum β-Lactamase-Producing Salmonella enterica Serovar Enteritidis Isolated from Patients in Shanghai, China

The emergence of extended-spectrum β-lactamase-producing Salmonella enterica serovar Enteritidis (ESBL-SE) in humans and foods has gained global attention. In particular, CTX-M-type ESBL-SE are increasingly being detected from various sample types. The aim of this study was to comprehensively analyze the epidemiology and characteristics of bla_CTX-M-55-carrying ESBL-SE isolates of clinical origin in Shanghai, China. A total of 292 S. Enteritidis isolates were recovered from the feces and blood of outpatients and inpatients between 2006 and 2014. Overall, there was a high frequency of cefotaxime-resistant isolates (97.3%), which was significantly higher (p < 0.01) than that of isolates resistant to the other tested antibiotics. All S. Enteritidis isolates exhibited resistance to ≥1 antibiotic, and 98.0% were multidrug resistant. A total of 233 isolates were identified as ESBL-SE, 166 of which were CTX-M type. Six subtypes of CTX-M-encoding genes were detected, among which bla_CTX-M-55 (91.6%, 152/166) was the most prevalent genotype. There was high genetic similarity among bla_CTX-M-55-positive ESBL-SE. The bla_CTX-M-55 gene in the ESBL-SE donor strains could be easily transferred into Enterobacteriaceae recipient strains. This study highlights that CTX-M-55 should be considered an important surveillance target in Shanghai, China. Cephalosporins, especially cefotaxime, must be used with caution in empirical treatment for Salmonella infections.

Molecular characterization of extended-spectrum β-lactamase-producing Escherichia coli isolated from postpartum uterine infection in dairy cattle in India

BACKGROUND AND AIM

Selection and dissemination of plasmid-encoded extended-spectrum β-lactamase (ESBL) among Enterobacteriaceae confers resistance to beta-lactam antibiotics. The purpose of this study was to determine the prevalence and molecular characteristics of ESBL-producing organisms isolated from dairy cattle with a uterine infection.

MATERIALS AND METHODS

Bacterial isolates (n=62) were characterized by biochemical test for genus and species determination. Antimicrobial susceptibility tests were performed by Kirby-Bauer disk diffusion method using panel of antibiotics for initial screening of ESBL organism. Phenotypic confirmation of ESBL-suspected strains was done by combination disk method and double-disk method. Multiplex polymerase chain reaction (PCR) was carried out for phylogrouping of Escherichia coli isolates as well as for genotyping ESBL genes. Enterobacterial repetitive intergenic consensus-PCR method was used for genotypic characterization of isolates.

RESULTS

Antibiotic susceptibility profile of E. coli (n=40) isolates showed high rates of resistance for ampicillin (95.0%), cefpodoxime (97.5%), cefotaxime (87.5%), and ceftriaxone (70%). However, low rates of resistance were observed for cefoxitin (25%), amoxicillin/clavulanic acid (20%), ceftazidime (17.5%), gentamicin (10%), and ertapenem (7.5%). A total of 39/40 E. coli isolates were confirmed as ESBL with Epsilometer test as well as the genotypic method and 28 (70%) of them were multidrug-resistant. Genotype blaCTX-M was observed as a predominant beta-lactamase type with the preponderance of CTX-M Group 1. The following combinations were observed: blaTEM + blaCTX-M in 15 (36.2%) isolates, blaTEM /blaSHV in 8 (5.2%) isolates, and blaCTX-M /blaSHV in 6 (5.2%) isolates. The phylogenetic grouping of E. coli strains revealed the highest prevalence for B1 (22.0%) followed by A (20%).

CONCLUSION

This report shows a high frequency of ESBL E. coli from cattle with postpartum uterine infections. These isolates showed reduced susceptibility to common antibiotics used for the treatment of uterine infections greater affecting the therapeutic outcome.

Higher prevalence of multidrug-resistant extended-spectrum β-lactamases producing Escherichia coli in unorganized pig farms compared to organized pig farms in Mizoram, India

Aim

The present study was conducted to record the prevalence of multidrug-resistant (MDR), extended-spectrum β-lactamases (ESBLs) producing Escherichia coli from pig population of organized and unorganized farms of Mizoram and to record the presence of ESBLs, non-ESBLs, and integrons.

Materials and Methods

Fecal samples were collected from pigs under organized (n=40) and unorganized (n=58) farms of Mizoram. Samples were processed for isolation and identification of E. coli by conventional techniques, BD Phoenix™ automated bacterial system, and polymerase chain reaction (PCR) based confirmatory test. All the isolates were subjected to antimicrobial sensitivity test by disk diffusion assay and ESBLs production by double-disk synergy test (DDST). The ESBLs producing isolates were subjected to PCR for determination of ESBLs genes and all the isolates were screened for non-ESBLs genes and integrons by PCR.

Results

A total of 258 E. coli was isolated and identified from organized (n=120) and unorganized farms (n=138). Majority of the E. coli isolates exhibited high level of resistance against amoxicillin (Ax) (81.78%), cefalexin (85.42%), co-trimoxazole (50.78%), sulfafurazole (69.38%), tetracycline (65.89%), and trimethoprim (TR) (51.94%). Statistically highly significant (p<0.01) variations in resistance among the isolates from organized and unorganized farms were recorded in case of Ax, ampicillin, cephalexin, ciprofloxacin, co-trimoxazole, gentamicin, piperacillin, and TR. By DDST, 65.89% isolates were recorded as ESBLs producer, of which 82/120 (68.33%) and 88/138 (63.77%) were from organized and unorganized farms, respectively. A total of 29/258 (11.24%) isolates were positive for at least one ESBLs gene. bla_TEM was most frequently (9.69%) gene, followed by bla_CTX -M (5.04%) and bla_CMY (0.78%). Altogether, 6 (5.00%), 4 (3.33%), and 2 (1.67%) isolates from the organized farms were positive for bla_CTX-M , bla_TEM , and bla_CMY genes, respectively. Similarly, 21 (15.22%) and 7 (5.07%) isolates from the unorganized farms were positive for bla_TEM and bla_CTX-M genes, respectively. None of them were positive for bla_SHV genes. Altogether 57 (22.09%), 9 (3.49%), 66 (25.58%), 78 (30.23%), 21 (8.14%), and 18 (6.98%) isolates were positive for tetA, tetB, sul1, sul2, aadA, and dfrla genes, respectively. The prevalence of non-ESBLs genes was higher in the E. coli isolates from the unorganized farms than organized farms.

Conclusion

MDR and ESBLs producing E. coli are circulating among the pigs and their environment in Mizoram. Pigs under unorganized farms exhibited higher level of resistance against majority of the antimicrobials, including third-generation cephalosporins, which might be an indication of overuse or misuse of antibiotics under the unorganized piggery sectors in Mizoram.

Extended-Spectrum β-Lactamases in Human Isolates of Multidrug-Resistant Non-typhoidal Salmonella enterica

A total of 291 non-duplicate isolates of non-typhoidal Salmonella (NTS) were collected from the fecal samples of patients with salmonellosis in Armenia and Georgia during 1996–2016. The isolates were tested for resistance to antimicrobials, including extended-spectrum β-lactamases (ESBL). The high prevalence of multidrug-resistance (MDR) and ESBL-producer phenotypes was detected among Salmonella enterica subsp. enterica serovar Typhimurium (S. Typhimurium) isolates collected from patients in Armenia between 1996 and 2016. A total of 36 MDR NTS isolates were subjected to whole genome sequencing (WGS) to determine the genetic background of antimicrobial resistance (AMR) and mobile genetic elements. All ESBL-producing S. Typhimurium isolates belonged to the same sequence type (ST328). The ESBL-producer phenotype was associated with plasmid-encoded CTX-M-5 production. A range of other plasmids was associated with resistance to other antimicrobials, including the MDR phenotype.

Molecular Characterization of Extended-Spectrum β-Lactamase-Producing Escherichia coli and Klebsiella pneumoniae Among the Pediatric Population in Qatar

INTRODUCTION

Although extended-spectrum β-lactamase (ESBL)-producing Enterobacterales are a public health problem in the Arabian Peninsula, data on the molecular characteristic of their antimicrobial resistance determinants in children is limited.

AIM

To determine the molecular characteristics of ESBL-producing Escherichia coli and Klebsiella pneumoniae in the pediatric population of Qatar.

METHODS

Whole-genome sequencing was performed on ESBL-producing E. coli and K. pneumoniae isolates recovered from screening and clinical specimens from pediatric patients at Sidra Medicine in Doha from January to December 2018.

RESULTS

A total of 327 ESBL producers were sequenced: 254 E. coli and 73 K. pneumoniae. Non-susceptibility rates to non-β-lactam antibiotics for both species were 18.1 and 30.1% for gentamicin, 0.8 and 4.1% for amikacin, 41.3 and 41.1% for ciprofloxacin, and 65.8 and 76.1% for cotrimoxazole. The most common sequence types (STs) were ST131 (16.9%), ST38 and ST10 (8.2% each) in E. coli and ST307 (9.7%), and ST45 and ST268 (6.9% each) in K. pneumoniae. CTX-M type ESBLs were found in all but one isolate, with CTX-M-15 accounting for 87.8%. Among other β-lactamases, TEM-1B and OXA-1 were coproduced in 41 and 19.6% of isolates. The most common plasmid-mediated quinolone resistance genes cocarried were qnr A/B/E/S (45.3%). Ninety percent of gentamicin non-susceptible isolates harbored genes encoding AAC(3) enzymes, mainly aac(3)-IIa. Only two of 57 isolates harboring aac(6')-Ib-cr were non-susceptible to amikacin. Chromosomal mutations in genes encoding DNA gyrase and topoisomerase IV enzymes were detected in 96.2% fluoroquinolone-non-susceptible E. coli and 26.7% fluoroquinolone-non-susceptible K. pneumoniae.

CONCLUSION

Our data show that CTX-M enzymes are largely the most prevalent ESBLs in children in Qatar with a predominance of CTX-M-15. Carbapenem-sparing options to treat ESBL infections are limited, given the frequent coproduction of OXA-1 and TEM-1B enzymes and coresistance to antibiotic classes other than β-lactams.

Extended-Spectrum β-Lactamase- and Carbapenemase-Producing Enterobacterales Intestinal Carriage Among Outpatients: Microbiological and Epidemiological Differences Between Private Dwelling Residents and Nursing Home Residents

The aim of this work was to assess the prevalence of carbapenemase-producing and extended-spectrum β-lactamase-producing Enterobacterales (ESBLPE) intestinal carriage among private dwelling residents (PDR) and nursing home residents (NHR) from the catchment area of Hospital Verge de la Cinta (Tortosa. North-Eastern Spain), and to depict clinicoepidemiological features of colonized individuals. Prevalence of ESBLPE carriage amid 762 PDR (0-94 years) who had feces collected for routine culture was 7.3% and 31% among 71 NHR (68-98 years) screened upon hospital admission. The mean age of colonized and noncolonized subjects was 30 and 32.8 years in PDR (p = 0.58) and 85 and 87 years in NHR (p = 0.32). The predominant ESBLPE was CTX-M-15-producing Escherichia coli (42.8% in PDR and 68.2% in NHR [25% and 86.7% belonging to O25b-ST131 clone; p < 0.0001]), followed by CTX-M-9-group- and SHV-producing E. coli and by CTX-M-15-producing Klebsiella pneumoniae. Overall, 72.7% of ESBLPE were multidrug resistant and 46.2% carried transferable quinolone determinants. Institutionalization in a nursing home was a risk factor for ESBLPE and extended-spectrum β-lactamase (ESBL)-producing O25b-ST131 E. coli carriage in individuals over 67 years (odds ratio 7.7 and 14.1). Previous antibiotic use and skin ulcers were significantly associated with ESBLPE carriage in NHR. Age <25 years in PDR and amoxicillin/clavulanate exposure in NHR protected against ESBL-producing O25b-ST131 E. coli colonization. Only two PDR, with known risk factors, bore OXA-48-producing isolates. These results highlight the role of nonhospitalized intestinal carriers, particularly NHR, as ESBLPE reservoirs and the preponderance of CTX-M-15, mainly linked to O25b-ST131 clone, as well as the emergence of carbapenemase-producing Enterobacterales carriers.

Beneficial Chromosomal Integration of the Genes for CTX-M Extended-Spectrum β-Lactamase in Klebsiella pneumoniae for Stable Propagation

Dominant F-type plasmids harboring the gene have been pointed out to be responsible for the dissemination of the CTX-M extended-spectrum-β-lactamase (ESBL)-producing K. pneumoniae. Recently, the emergence of K. pneumoniae isolates with the bla_CTX-M gene in their chromosomes has been reported occasionally worldwide. Such a chromosomal location of the resistance gene could be beneficial for stable propagation, as was the Acinetobacter baumannii ST191 harboring chromosomal bla_OXA-23 that is endemic to South Korea. Through the present study, particular clones were identified as having built-in resistance genes in their chromosomes, and the chromosomal integration events were tracked by assessing their genomes. The cefotaxime-resistant K. pneumoniae clones of this study were particularized as results of the fastidiousness for plasmids to acquire the bla_CTX-M gene for securing the diversity and of the chromosomal addiction of the bla_CTX-M gene for ensuring propagation.

The acquired CTX-M-type extended-spectrum-β-lactamase (ESBL)-producing Enterobacterales are of great concern in clinical settings because they limit therapeutic options for patients infected by the pathogens. An intriguing clonality of CTX-M ESBL-producing Klebsiella pneumoniae blood isolates was observed from a national cohort study, and comparative genomics were assessed for the 115 K. pneumoniae blood isolates carrying the bla_CTX-M gene. The plasmid preference of particular clones of a sequence type (ST) was assessed by liquid mating. A quarter of the bla_CTX-M gene-carrying K. pneumoniae blood isolates harbor the gene in their chromosome, and most of those with the built-in bla_CTX-M gene belonged either to ST307 or ST48. Notably, all 16 K. pneumoniae ST48 isolates harbored two copies of the bla_CTX-M-15 gene in the chromosome. The chromosomal integration of the bla_CTX-M-15 gene was mostly derived from the ISEcp1-targeting 5-bp AT-rich locus in the chromosome. The IS26-mediated chromosomal integration occurred when the upstream ISEcp1 from the bla_CTX-M gene was truncated, targeting the anchor IS26 copy in the chromosome. Higher transfer efficiency of the bla_CTX-M-15 gene-carrying FIA:R plasmid was observed in ST17 than that of the bla_CTX-M-14 gene-carrying FIB:FII plasmid. The transfer efficiency of the plasmid differed by isolate among the ST307 members. The K. pneumoniae clones ST307 and ST48 harboring the bla_CTX-M-15 gene in the chromosome were able to disseminate stably in clinical settings regardless of the environmental pressure, and the current population of K. pneumoniae blood isolates was constructed. Further follow-up is needed for the epidemiology of this antimicrobial resistance.

IMPORTANCE Dominant F-type plasmids harboring the gene have been pointed out to be responsible for the dissemination of the CTX-M extended-spectrum-β-lactamase (ESBL)-producing K. pneumoniae. Recently, the emergence of K. pneumoniae isolates with the bla_CTX-M gene in their chromosomes has been reported occasionally worldwide. Such a chromosomal location of the resistance gene could be beneficial for stable propagation, as was the Acinetobacter baumannii ST191 harboring chromosomal bla_OXA-23 that is endemic to South Korea. Through the present study, particular clones were identified as having built-in resistance genes in their chromosomes, and the chromosomal integration events were tracked by assessing their genomes. The cefotaxime-resistant K. pneumoniae clones of this study were particularized as results of the fastidiousness for plasmids to acquire the bla_CTX-M gene for securing the diversity and of the chromosomal addiction of the bla_CTX-M gene for ensuring propagation.

Colistin Heteroresistance among Extended Spectrum β-lactamases-Producing Klebsiella pneumoniae

Colistin-heteroresistant (CST-HR) Enterobacterales isolates have been identified recently, challenging the clinical laboratories since routine susceptibility tests fail to detect this phenotype. In this work we describe the first CST-HR phenotype in extended-spectrum β-lactamase (ESBL)-producing Klebsiella pneumoniae isolates in South America. Additionally, we determine the genomic mechanisms of colistin heteroresistance in these strains. The CST-HR phenotype was analyzed by the population analysis profile (PAP) method, and mutations associated with this phenotype were determined by whole-genome sequencing (WGS) and the local BLAST+ DB tool. As a result, 8/60 isolates were classified as CST-HR according to the PAP method. From WGS, we determined that the CST-HR isolates belong to three different Sequence Types (STs) and four K-loci: ST11 (KL15 and KL81), ST25 (KL2), and ST1161 (KL19). We identified diverse mutations in the two-component regulatory systems PmrAB and PhoPQ, as well as a disruption of the mgrB global regulator mediated by IS1-like and IS-5-like elements, which could confer resistance to CST in CST-HR and ESBL-producing isolates. These are the first descriptions in Chile of CST-HR in ESBL-producing K. pneumoniae isolates. The emergence of these isolates could have a major impact on the effectiveness of colistin as a “last resort” against these isolates, thus jeopardizing current antibiotic alternatives; therefore, it is important to consider the epidemiology of the CST-HR phenotype.

Escherichia coli Producing Extended-Spectrum β-lactamases (ESBL) from Domestic Camels in the Canary Islands: A One Health Approach

Simple Summary

Extended-spectrum beta-lactamase (ESBL) producing Escherichia coli is an important problem in hospital settings. Camels are known to harbor multidrug-resistant Gram-negative bacteria and to be involved in the transmission of various microorganisms to humans. Fecal samples of 58 camels were recovered in the Canary Islands for detection and characterization of cefotaxime-resistant (CTX^R) and ESBL-producing E. coli isolates. Five samples carried CTX^RE. coli isolates and two of them contained ESBL-positive E. coli (3.4%) with the following characteristics: (ESBL/phylogroup/sequence type): CTX-M-15/A/ST3018 and CTX-M-15/B1/ST69. The three remaining isolates recovered from CTX-supplemented plates were ascribed to phylogroup-B₁. Due to the participation of these animals in touristic activities in the region, the potential transference of ESBL-positive bacteria between humans and animals could happen and should be further monitored.

Abstract

Objective: This work aimed to determine the carriage rate of ESBL-producing Escherichia coli as well as their genetic characteristics in camels from the Canary Islands, Spain. Methods: Fecal samples were recovered from 58 healthy camels from Gran Canaria (n = 32) and Fuerteventura Islands (n = 26) during July 2019. They were seeded on MacConkey (MC) agar no supplemented and supplemented (MC + CTX) with cefotaxime (2 µg/mL). Antimicrobial susceptibility was determined by disk diffusion test (CLSI, 2018). The presence of bla_CTX-M, bla_SHV, bla_TEM,bla_CMY-2 and bla_OXA-1/48 genes was tested by PCR/sequencing. Furthermore, the mcr-1 (colistin resistance), tetA/tetB (tetracycline resistance), int1 (integrase of class 1 integrons) and stx_1,2 genes were analyzed. Phylogenetic groups and sequence types were determined by specific-PCR/sequencing for selected isolates. Results: E. coli was obtained from all the 58 camels in MC media (100%) and in five of them in MC + CTX media (8.6%). Furthermore, 63.8% of E. coli isolates recovered from MC agar were susceptible to all the antibiotics tested. The five E. coli isolates recovered from MC + CTX media were characterized and two of them were ESBL-producers (3.4%). Both ESBL-producer isolates carried the bla_CTX-M-15 gene and belonged to the lineages ST3018 (phylogroup A) and ST69 (phylogroup B1). The 3 ESBL-negative isolates recovered from MC-CTX plates were ascribed to phylogroup-B₁. Conclusions: Camels can be a source of ESBL-producer bacteria, containing the widespread bla_CTX-M-15 gene associated with the lineages ST3018 and ST69.

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

Objective

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

Materials and Methods

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

Results

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

Conclusion

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

Colonization With Multidrug-Resistant Organisms Among Healthy Adults in the Community Setting: Prevalence, Risk Factors, and Composition of Gut Microbiome

BACKGROUND

The prevalence of colonization with multidrug-resistant organisms (MDROs) among healthy adults in the community is largely unknown. This study investigated the colonization rate of multidrug-resistant Enterobacteriaceae, methicillin-resistant Staphylococcus aureus (MRSA), and vancomycin-resistant enterococci (VRE) in the community in Taiwan, and compared the gut microbiota between MDRO carriers and non-carriers.

METHODS

This prospective cohort study was conducted from March 2017 to February 2018 at the Hsin-Chu and Jin-Shan branches of National Taiwan University Hospital. Nasal swabs and stool samples were obtained from healthy adults attending a health examination to screen for MDROs. Bacteria isolates of MDROs were tested for antibiotic susceptibility and resistant genes. Relevant data were collected using a standardized questionnaire to evaluate the risk factors for MDROs carriage, and 16S rRNA metagenomics sequencing was performed to analyze gut microbiota.

RESULTS

Among 187 participants, 4.6% (8/174) carried MRSA and 41.4% (77/186) carried third-generation cephalosporin-resistant (3GC-R) Escherichia coli or Klebsiella pneumoniae. The carriage rate of AmpC beta-lactamases and ESBL-producing strains were 16.1 and 27.4%, respectively. No carbapenem-resistant Enterobacteriaceae (CRE) or VRE were detected. The dominant resistant gene of E. coli isolates was CTX-M-type (73%), while that of K. pneumoniae was AmpC beta-lactamases (80%). In the multivariate analysis, the significant risk factors for carrying 3GC-R E. coli or K. pneumoniae were being an employee of technology company A [adjusted odds ratio (aOR) 4.127; 95% confidence interval (CI) 1.824-9.336; p = 0.001], and traveling to Southeast Asia in the past year (aOR 6.545; 95% CI 1.071-40.001; p = 0.042). The gut microbiota analysis showed that the phylum Proteobacteria and the family Enterobacteriaceae were significantly more abundant in 3GC-R E. coli and K. pneumoniae carriers.

CONCLUSION

A high rate of Taiwanese adults in the community carried 3GC-R Enterobacteriaceae, while no CRE or VRE colonization was noted. Compared with non-carriers, an expansion of Enterobacteriaceae in gut microbiota was found among 3GC-R Enterobacteriaceae carriers.

Plasmid Profiling and Occurrence of β-Lactamase Enzymes in Multidrug-Resistant Uropathogenic Escherichia coli in Kathmandu, Nepal

INTRODUCTION

Extended-spectrum β-lactamases (ESBL) among Gram-negative bacteria, predominantly Escherichia coli (E. coli), in Nepal, have been rising. The main objectives of this study were to determine the prevalence of uropathogenic E. coli, antibiotic resistance, ESBLs, ABLs (AmpC type β-lactamases), MBLs (metallo-β-lactamases) and KPCs (Klebsiella pneumoniae carbapenemases) and their correlation with plasmid profiling patterns among patients with urinary tract infections in a tertiary hospital in Kathmandu, Nepal.

METHODS

The mid-stream urine samples collected from patients were inoculated in cystine-lactose-electrolyte-deficient (CLED) agar plates. E. coli producing ESBLs, ABLs, MBLs/KPC were identified phenotypically using standard microbiological methods. Plasmids were extracted by alkaline lysis method from E. coli isolates and profiled using agarose gel electrophoresis.

RESULTS

Out of the total 2661 urine samples, E. coli were isolated in 64.34% (507/788), among which 170 (33.53%) were multidrug-resistant (MDR) isolates. All MDR isolates were resistant to amoxicillin and third-generation cephalosporins but were highly sensitive to imipenem (94.12%, 160/170), amikacin (92.94%, 158/170) and nitrofurantoin (86.47%, 147/170). Among 170 MDR isolates, 78.2% (133/170) were ESBLs, 46.3% (50/170) were AmpC, 11.2% (19/170) were MBL and 0.6% (1/170) were KPC producers. Coproduction of β-lactamases was detected in 24.12% (41/170) of isolates. E. coli isolates showed one plasmid (>33.5 kb), which was present in all the isolates. Overall, 44 different plasmid profile groups were identified based on molecular weight and number of plasmids. β-Lactamase producers were relatively resistant to the higher number of antibiotics tested (≤10) than non-producers (≤8), and the number of plasmids were higher in β-lactamase producers (≤7) than those in non-producers (≤5).

CONCLUSION

The higher prevalence of the ESBLs, AmpCs, KPCs and MBLs along with their coproduction in E. coli isolates highlights the importance of routine surveillance of ESBLs, AmpCs, KPCs and MBLs in microbiology laboratories using various phenotypic methods.

Association of CRISPR/Cas System with the Drug Resistance in Klebsiella pneumoniae

Background

Klebsiella pneumoniae is a common opportunistic pathogen and its production of extended-spectrum β-lactamases (ESBL) and carbapenemases leads to drug resistance. Clustered regularly interspaced short palindromic repeats (CRISPRs) and their associated genes (Cas) are widespread in the genome of many bacteria and are a defense mechanism against foreign invaders such as plasmids and viruses.

Purpose

To investigate the prevalence of the CRISPR/Cas system in wild type strains of K. pneumoniae in the hospital and its association with drug resistance.

Materials and Methods

A total of 136 strains were collected and characterized their susceptibility to antimicrobial agents. The prevalence of CRISPR/Cas system was detected by PCR and DNA sequencing was analyzed by CRISPRFinder. The statistical analysis of the results was performed by SPSS.

Results

We found that 50/136 (37%) isolates produced ESBL and 30/136 (22%) isolates were resistant to carbapenems. These isolates were liable to be multidrug resistant against β-lactams, quinolones, and aminoglycosides. Among the carbapenem-resistant isolates, blaKPC was the main drug resistance-associated gene and different types of ESBL and AmpC genes were present. Resistance to β-lactams, quinolones, aminoglycosides, tetracyclines, and β-lactams/enzyme inhibitor were higher in absence of the CRISPR/Cas system. Eighteen spacers within the CRISPR arrays matched with the genomes of plasmids or phages, some of which carried drug resistance genes.

Conclusion

ESBL-producing and carbapenem-resistant K. pneumoniae are more likely to develop multidrug resistance and show an inverse correlation between drug resistance and CRISPR/Cas system. Absence of CRISPR/Cas modules allow for the acquisition of external drug resistance genes.

Phenotypic and Genotypic Prevalence of Extended-Spectrum β-Lactamase-Producing Escherichia coli: A Systematic Review and Meta-Analysis in Iran

Background: Despite the existence of discrete and varied studies regarding extended-spectrum β-lactamase-producing Escherichia coli (ESBL-EC) in Iran, a comprehensive analysis on the prevalence of ESBL-EC has not yet been carried out. The current study analyzed published data regarding ESBL-EC in different regions of Iran to gain insight into this significant subject. Methods: A meta-analysis was performed using Comprehensive Meta-Analysis Software (version 2.2; Biostat) to determine the prevalence of ESBL-EC in Iran. A web-based search was conducted in electronic databases, including PubMed, Scopus, and Web of Sciences. The eligibility of articles published between 2008 and 2018 was assessed, and relevant data were extracted for statistical analysis. A random-effects model was used based on the heterogeneity test. Publication bias was determined using Begg's rank correlation and Egger's weighted regression methods. Results: Among 31,135 studies examined, 61 met inclusion criteria and were included for review. Iran's overall pooled proportion of ESBL-EC was 43.2% (confidence interval [95% CI] 39.2-47.3), and the overall heterogeneity (I²) between studies was significantly high (93.5%, p = 0.00). The most prevalent of ESBLs in E. coli was CTX-M and TEM, with prevalence of 31.2% (95% CI 25.4-37.6), 27.6% (95% CI 22.7-33.2), respectively. Conclusion: The available studies show a high rate of ESBL-EC in Iran. This result highlights a need for appropriate and rapid methods for estimating ESBL infection, which can help our understanding of the actual epidemiology of ESBL and provide protocols for the prevention and control of infection.

Characteristics of Hypervirulent Klebsiella pneumoniae: Does Low Expression of rmpA Contribute to the Absence of Hypervirulence?

Multidrug-resistant hypervirulent Klebsiella pneumoniae (MDR-hvKP) has been increasingly reported and is now recognized as a significant threat to public health; however, characterization of MDR-hvKP has not been systematically investigated. In the present study, 124 of 428 (28.92%) K. pneumoniae clinical isolates collected from January 2010 to December 2016 were identified with aerobactin and defined as hvKP; these included 94 non-MDR-KP, 20 extended-spectrum β-lactamase-producing K. pneumoniae (ESBL-KP), and 10 carbapenem-resistant K. pneumoniae (CR-KP) isolates. The remaining 304 isolates without presence of virulence factor aerobactin were defined as classic K. pneumoniae (cKP). The antimicrobial resistance rate of cKP was significantly higher than that of the hvKP isolates in the non-MDR-KP group, but showed no significant differences in the ESBL-KP and CR-KP groups. The detection frequencies of capsular serotype K1 (magA), hypermucoviscosity, sequence type 23 (ST23), and the virulence gene rmpA were significantly higher in the hvKP than cKP isolates in all three groups (P < 0.05). Most of the hypervirulent ESBL-KP and CR-KP isolates were K non-typeable (16/30) and harbored at least one gene for virulence (26/30). The hypervirulent ESBL-KP isolates primarily carried bla_CTX–M (12/20, 60%) genes, and the hypervirulent CR-KP isolates mainly carried bla_NDM–1 (8/10, 80%) genes. Moreover, three hypervirulent ESBL-KP and two hypervirulent CR-KP isolates showed resistance to tigecycline but were sensitive to colistin. The transcriptional levels of rmpA in cKP were much lower than that in hvKP isolates in all three groups. Furthermore, overexpression of rmpA in the rmpA-low-expression cKP isolates could enhance bacterial virulence in the mouse infection experiment. In conclusion, our data suggest that the capsular serotype K1 (magA), rmpA, hypermucoviscosity, and ST23 were strongly associated with hvKP in non-MDR-KP, ESBL-KP, and CR-KP groups, and low rmpA expression levels contributed to the absence of hypervirulent phenotype.

Resistance to multiple first-line antibiotics among Escherichia coli from poultry in Western Algeria

BACKGROUND AND AIM

Escherichia coli can cause a number of serious infections both in human and veterinary medicine. Their management is increasingly complicated by the emergence and dissemination of multiresistance to various first-line antimicrobial agents. This study aimed to evaluate the resistance level to the commonly used antibiotics, with a focus on the first-line antimicrobial agents, in E. coli strains isolated from poultry in Western Algeria.

MATERIALS AND METHODS

E. coli culture was done on MacConkey agar and their identification was determined by AP20E system. For susceptibility testing, disk diffusion method to 14 antimicrobials, including first-line antibiotics, was used according to Kirby-Bauer disk diffusion method in Mueller-Hinton agar and the results were interpreted according to the Clinical and Laboratory Standards Institute guidelines. E. coli isolates were considered as multidrug resistance (MDR) when found resistant to at least one antimicrobial agent of three different families of antibiotics. Double-disk synergy and combination disk tests were used for initial screening and confirmation for extended-spectrum β-lactamases (ESBLs) production, respectively.

RESULTS

A total of 145 E. coli strains were isolated in this study. High resistance levels to various antibiotics, including commonly used first-line antimicrobial agents, were recorded in this study. The highest resistance level was observed against nalidixic acid (90.34%, n=131), followed by tetracycline (86.89%, n=126), ampicillin (82.75%, n=120), enrofloxacin (80.68%, n=117) and neomycin (80.68%, n=117), trimethoprim/sulfamethoxazole (73.79%, n=107), norfloxacin (72.41%, n=105) and cephalothin (72.41%, n=105), amoxicillin/clavulanic acid (51.72%, n=75), chloramphenicol (22.75%, n=33), nitrofurantoin (17.24%, n=25), gentamicin (13.10%, n=19), and ceftiofur (3.44%, n=5). Moreover, resistance to multiple first-line antibiotics was also demonstrated in the present study. Overall, 139 out of 145 isolates (95.86%) demonstrated MDR (resistant to at least three antibiotics). In addition, five E. coli isolates (3.44%) were confirmed to be ESBL producers.

CONCLUSION

The alarming rate of E. coli resistant to multiple first-line antibiotics in poultry demands intensified surveillance. These results call for taking drastic measures to preserve antibiotic effectiveness and reduce the emergence risks of extensively drug-resistant and pandrug-resistant E. coli isolates.

Nutrition Related Stress Factors Reduce the Transfer of Extended-Spectrum Beta-Lactamase Resistance Genes between an Escherichia coli Donor and a Salmonella Typhimurium Recipient In Vitro

The transfer of extended spectrum β-lactamase (ESBL)-genes occurs frequently between different bacteria species. The aim of this study was to investigate the impact of nutrition related stress factors on this transfer. Thus, an Escherichia coli donor and a Salmonella Typhimurium recipient were co-incubated for 4 h in media containing different levels of the stress factors' pH, osmolality, copper, zinc and acetic, propionic, lactic, and n-butyric acid, as well as subtherapeutic levels of cefotaxime, sulfamethoxazole/trimethoprim, and nitrofurantoin. Conjugation frequencies were calculated as transconjugants per donor, recipient, and total bacterial count. A correction factor for the stress impact on bacterial growth was used. Acetic, lactic, and n-butyric, acid, as well as pH, showed no significant impact. In contrast, increasing concentrations of propionate, zinc, copper, and nitrofurantoin, as well as increased osmolality reduced conjugation frequencies. Sulfamethoxazole/trimethoprim and cefotaxime showed increased transconjugants per donor, which decreased after correction for stress. This study showed, for the model mating pair, that conjugation frequencies decreased under different physiological stress conditions, and, thus, the hypothesis that stress factors may enhance conjugation should be viewed with caution. Furthermore, for studies on in vitro gene transfer, it is vital to consider the impact of studied stressors on bacterial growth.

Meat and Fish as Sources of Extended-Spectrum β-Lactamase-Producing Escherichia coli, Cambodia

We compared extended-spectrum β-lactamase-producing Escherichia coli isolates from meat and fish, gut-colonized women, and infected patients in Cambodia. Nearly half of isolates from women were phylogenetically related to food-origin isolates; a subset had identical multilocus sequence types, extended-spectrum β-lactamase types, and antimicrobial resistance patterns. Eating sun-dried poultry may be an exposure route.

In Vivo Pharmacodynamic Profile of Ceftibuten-Clavulanate Combination against Extended-Spectrum-β-Lactamase-Producing Enterobacteriaceae in the Murine Thigh Infection Model

Ceftibuten-clavulanate (CTB-CLA) is a novel β-lactam-β-lactamase combination with potential utility for the management of urinary tract infections caused by extended-spectrum-β-lactamase (ESBL)-producing organisms. We examined the pharmacodynamics of the combination against 25 Enterobacteriaceae expressing β-lactamases (CTX-M, TEM, and SHV wild types and SHV-ESBL) in the murine thigh infection model. MIC values of CTB and CTB-CLA ranged from 1 to >32 mg/liter and 0.125 to 8 mg/liter, respectively. Human-simulated regimens of CTB and CLA equivalent to clinical doses of 400 mg orally (p.o.) every 8 h (q8h) and 187 mg q8h, respectively, were developed. CLA dose fractionation studies were undertaken to characterize the driver of efficacy. CLA dose-ranging studies were undertaken to assess the activity of the CTB human-simulated regimen in combination with escalating CLA exposures. The relationships between the percentage of the dosing interval during which the free CLA plasma concentrations remained above a threshold concentration (%fT>C_T ) and the change in log₁₀ CFU per thigh at 24 h were examined across different threshold concentrations. Additionally, the efficacy of a human-simulated regimen of CTB-CLA was assessed against isolates with various susceptibilities to the combination. The pharmacokinetic/pharmacodynamic index that best correlated with the efficacy of the combination was %fT > threshold CLA plasma concentration of 0.5 mg/liter. The plasma %fT>0.5 mg/liter associated with the static endpoint was 20.59%. For isolates with CTB-CLA MICs of ≤4 mg/liter, stasis was achieved with a human-simulated regimen of CTB-CLA against 20/22 isolates (90.9%), while for isolates with MICs of 8 mg/liter, only 1/3 tested isolates (33.3%) displayed stasis. Results suggest a susceptibility breakpoint of 4 mg/liter for CTB-CLA. These data support the consideration of the CTB-CLA combination for the treatment of urinary tract infections due to ESBL-producing Enterobacteriaceae.

Rapid Increase in Carriage Rates of Enterobacteriaceae Producing Extended-Spectrum β-Lactamases in Healthy Preschool Children, Sweden

By collecting and analyzing diapers, we identified a >6-fold increase in carriage of extended-spectrum β-lactamase (ESBL)–producing Enterobacteriaceae for healthy preschool children in Sweden (p<0.0001). For 6 of the 50 participating preschools, the carriage rate was >40%. We analyzed samples from 334 children and found 56 containing >1 ESBL producer. The prevalence in the study population increased from 2.6% in 2010 to 16.8% in 2016 (p<0.0001), and for 6 of the 50 participating preschools, the carriage rate was >40%. Furthermore, 58% of the ESBL producers were multidrug resistant, and transmission of ESBL-producing and non–ESBL-producing strains was observed at several of the preschools. Toddlers appear to be major carriers of ESBL producers in Sweden.

Frequency of infections caused by ESBL-producing bacteria in a pediatric ward - single-center five-year observation

INTRODUCTION

Infections caused by Enterobacteriaceae producing extended-spectrum β-lactamases (ESBLs) are a serious therapeutic and clinical problem. An increasing role of ESBL(+) pathogens is observed in both community- and hospital-acquired infections. The aim of the study was to assess the incidence and the risk factors for ESBL(+) bacteria infection in a pediatric ward during a 5-year period.

MATERIAL AND METHODS

The medical documentation data of patients hospitalized in the Department of Pediatrics, Pediatric Nephrology and Allergology between 2011 and 2015 were subjected to a retrospective analysis. Cases of ESBL(+) bacterial infections were analyzed in detail.

RESULTS

0.57% (46) of all the hospitalizations (8015) during the 5-year observation period in our department were caused by ESBL (+) pathogens. It constituted 8.5% of all positive microbiological cultures obtained. The analysis revealed an increasing trend in the number of ESBL (+) infections throughout the observed period. 43.5% of patients were only asymptomatic carriers. In 71.7% urinary tract structural and functional abnormalities were present. 76.1% of patients had been hospitalized previously and 60.9% had undergone urinary tract invasive procedures.

CONCLUSIONS

The results confirm the rising trend of ESBL (+) infections during the observed period. ESBL (+) bacteria were isolated primarily in previously hospitalized children with particular reference to urinary tract invasive procedures during hospitalizations. Moreover, the study showed that patients with urogenital disorders and non-urinary chronic diseases are more susceptible to these priority pathogen infections.

High Prevalence of Antimicrobial Resistance in Gram-Negative Bacteria Isolated from Clinical Settings in Egypt: Recalling for Judicious Use of Conventional Antimicrobials in Developing Nations

This study was designed to investigate, at the molecular level, the antimicrobial resistance mechanisms of different antimicrobial resistance genes, including, extended-spectrum β-lactamases, AmpC β-lactamases, class 1 and 2 integrons, and plasmid-mediated quinolone resistance genes of Gram-negative bacteria isolated from clinical settings in Egypt. A total of 126 nonduplicate Gram-negative isolates were recovered from different clinical samples taken from hospitalized patients in Egypt in 2014. Antimicrobial susceptibility testing showed that, 93.6% (118/126) of the isolates had a multidrug-resistant phenotype. Interestingly, we reported a high level of antimicrobial resistance nearly for all tested antibiotics; to our knowledge, this is the first report from Egypt indicating very high level of antibiotic resistance in Egypt. Polymerase chain reaction screening and DNA sequencing revealed that, 75.4% (95/126) of the isolates harbored at least one extended-spectrum β-lactamase-encoding gene, with bla_CTX-M being the most prevalent (65.9%), followed by bla_SHV (46.8%). The AmpC β-lactamase, bla_CMY, was detected in 7.1% (9/126) of bacterial isolates, with bla_CMY-42 being the most prevalent. Class 1 integrons were detected in 50.8% (64/126) of the isolates, and class 2 integrons were detected in 2.4% (3/126) of the isolates. The plasmid-mediated quinolone resistance gene, qnr, was detected in 58.7% (74/126) of the tested isolates, with qnrS being the most prevalent. Several antimicrobial resistance determinants were identified in Egypt for the first time, such as SHV-27, SHV-28, SHV-33, SHV-63, SHV-71, SHV-82, SHV-142, CMY-42, CMY-6, and the new CMY-72 like. This study highlights the importance of the conscious use of conventional antimicrobials to overcome the multidrug resistance problem.

Duration of Colonization by Extended-Spectrum β-Lactamase-Producing Enterobacteriaceae in Healthy Newborns and Associated Risk Factors: A Prospective Cohort Study

Duration of colonization by extended-spectrum β-lactamase-producing Enterobacteriaceae (ESBL-E) and factors associated with it were studied in 20 newborns in Seville, Spain. Median duration of colonization was 7.5 months; factors associated with prolonged colonization were delivery by caesarean section, colonization of the mother, and phylogroup B2 Eschericha coli isolate.