High Prevalence of Multidrug-Resistant Escherichia coli in Urine Samples from Inpatients and Outpatients at a Tertiary Care Hospital in Sétif, Algeria

Phenotypic Detection of Carbapenemase and AmpC-β-Lactamase Production among Extended Spectrum β-Lactamase (ESBL)-Producing Escherichia coli and Klebsiella spp. Isolated from Clinical Specimens

Introduction: Data on antimicrobial resistance (AMR) are sparse across numerous African countries, as microbiological analyses are not routinely conducted and surveillance data are not collected. Accordingly, clinical samples are not routinely tested for carbapenem-resistant bacteria and, therefore, the general understanding of their prevalence in the region remains limited. Methods: Between January 2020 and June 2022, we collected extended spectrum β-lactamase (ESBL)-producing Enterobacterales (ESBL-PE) isolates from five hospitals in Burkina Faso. After an initial culture on ESBL-selective media, the species were identified using API20E and isolates were tested against 13 antimicrobial agents using the disc diffusion method on Mueller-Hinton (MH) agar. ESBL production was confirmed via a double-disc synergy test. Production of carbapenemases and AmpC-β-lactamases and phenotypic co-resistance were determined. Results: Among the 473 ESBL-PE, 356 were ESBL-E. coli (ESBL-Ec) and 117 were Klebsiella spp. (ESBL-K). Of these isolates, 5.3% were carbapenemase and 5.3% were AmpC-β-lactamase-positive. Three types of carbapenemases were identified: 19 NDM, 3 OXA-48-like and 1 VIM. Two isolates produced both NDM and OXA-48-like carbapenemases. Carbapenemase producers were detected at all levels of healthcare. Co-resistance rates were up to 85% for aminoglycosides, 90% for sulfonamides, 95% for fluoroquinolones and 25% for chloramphenicol. Fosfomycin resistance was 6% for ESBL-Ec and 49% for ESBL-K (49%). Conclusions: Some of the ESBL-Ec and ESBL-K co-produced carbapenemases and/or AmpC-β-lactamases at all healthcare levels and in various sample types with high co-resistance rates to non-betalactams. Carbapenem resistance is no longer rare, calling for testing in routine diagnostics, a comprehensive resistance surveillance system and infection control within healthcare.

Novel Antibacterial Agents SAAP-148 and Halicin Combat Gram-Negative Bacteria Colonizing Catheters

The antibiotic management of catheter-related infections (CRIs) often fails owing to the emergence of antimicrobial-resistant strains and/or biofilm/persister apparitions. Thus, we investigated the efficacy of two novel antimicrobial agents, i.e., the synthetic peptide SAAP-148 and the novel antibiotic halicin, against Gram-negative bacteria (GNB) colonizing catheters. The antibacterial, anti-biofilm, and anti-persister activities of both agents were evaluated against Acinetobacter baumannii, Escherichia coli, and Klebsiella pneumoniae strains. The enrolled strains were isolated from catheters and selected based on their resistance to at least three antibiotic classes and biofilm formation potential. Furthermore, the hemolysis and endotoxin neutralization abilities of these agents were explored. The bactericidal activity of both agents was reduced in urine and plasma as compared to buffered saline. In a dose-dependent manner, SAAP-148 and halicin reduced bacterial counts in 24 h preformed biofilms on silicone elastomer discs and eliminated persisters originating from antibiotic-exposed mature 7-day biofilms, with halicin being less effective than SAAP-148. Importantly, SAAP-148 and halicin acted synergistically on E. coli and K. pneumoniae biofilms but not on A. baumannii biofilms. The peptide, but not halicin, decreased the production of IL-12p40 upon exposure to UV-killed bacteria. This preliminary study showed that SAAP-148 and halicin alone/in combination are promising candidates to fight GNB colonizing catheters.

Uropathogenic Escherichia coli endeavors: an insight into the characteristic features, resistance mechanism, and treatment choice

Uropathogenic Escherichia coli (UPEC) are the strains diverted from the intestinal status and account mainly for uropathogenicity. This pathotype has gained specifications in structure and virulence to turn into a competent uropathogenic organism. Biofilm formation and antibiotic resistance play an important role in the organism's persistence in the urinary tract. Increased consumption of carbapenem prescribed for multidrug-resistant (MDR) and Extended-spectrum-beta lactamase (ESBL)-producing UPECs, has added to the expansion of resistance. The World Health Organization (WHO) and Centre for Disease Control (CDC) placed the Carbapenem-resistant Enterobacteriaceae (CRE) on their treatment priority lists. Understanding both patterns of pathogenicity, and multiple drug resistance may provide guidance for the rational use of anti-bacterial agents in the clinic. Developing an effective vaccine, adherence-inhibiting compounds, cranberry juice, and probiotics are non-antibiotical approaches proposed for the treatment of drug-resistant UTIs. We aimed to review the distinguishing characteristics, current therapeutic options and promising non-antibiotical approaches against ESBL-producing and CRE UPECs.

Extended Spectrum β-Lactamase-Producing Escherichia coli from Poultry and Wild Birds (Sparrow) in Djelfa (Algeria), with Frequent Detection of CTX-M-14 in Sparrow

Antimicrobial resistance is a global threat that is spreading more and more in both human and animal niches. This study investigates the antimicrobial resistance and virulence threats of Escherichia coli isolates recovered from intestinal and fecal samples of 100 chickens, 60 turkeys, and 30 sparrows. Extended spectrum β-lactamase (ESBL) producing E. coli isolates were recovered in 12 of the animals tested, selecting one isolate per positive animal: sparrow (eight isolates, 26.7%), turkey (three isolates, 5%), and chicken (one isolate, 1%). The E. coli isolates were ascribed to B1 and D phylogenetic groups. The bla_CTX-M-14 gene was detected in all ESBL-producing E. coli isolates from sparrow. The bla_CTX-M-15 (two isolates) and bla_CTX-M-14 genes (one isolate) were detected in the isolates of turkey, and the bla_CTX-M-1 gene in one isolate from broiler. Three lineages were revealed among the tested isolates (ST/phylogenetic group/type of ESBL/origin): ST117/D/CTX-M-1/broiler, ST4492 (CC405)/D/CTX-M-15/turkey, and ST602/B1/CTX-M-14/sparrow. All isolates were negative for stx1, sxt2, and eae virulence genes. Our findings provide evidence that the sparrow could be a vector in the dissemination of ESBL-producing E. coli isolates to other environments. This study also reports, to our knowledge, the first detection of bla_CTX-M-14 from sparrow at a global level and in turkey in Algeria.

Multidrug-Resistant Enterobacterales in Community-Acquired Urinary Tract Infections in Djibouti, Republic of Djibouti

The emergence and spread of multidrug resistant Enterobacterales (MDR-E) are a global public health issue. This problem also concerns urinary tract infections (UTI), which are the second most frequent infections after respiratory infections. The objective of this study was to determine MDR-E frequency and to characterize MDR-E isolates from patients with community-acquired UTIs in Djibouti, Republic of Djibouti. From 800 clinical urinary samples collected at the Mer Rouge Laboratory, Djibouti, from January to July 2019, 142 were identified as Enterobacterales (age range of the 142 patients mean age is 42 years.) Mass spectrometry analysis of these isolates identified 117 Escherichia coli, 14 Klebsiella pneumoniae, 2 Proteus mirabilis, 4 Enterobacter spp., 4 Providencia stuartii and 1 Franconibacter helveticus. Antibiotic susceptibility testing (disk diffusion method) of these 142 isolates detected 68 MDR-E (68/142 = 48%): 65 extended-spectrum bêta lactamase- (ESBL), 2 carbapenemase- (one also ESBL), and 1 cephalosporinase-producer. Multiplex PCR and sequencing showed that the 65 ESBL-producing isolates carried genes encoding CTX-M enzymes (CTX-M-15 in 97% and CTX-M-9 in 3% of isolates). Two isolates harboured a gene encoding the OXA-48-like carbapenemase, and one the gene encoding the AmpC CMY-2 cephalosporinase. Genes implicated in resistance to quinolones (qnrB, aac (6')-Ib-cr, qnrD, oqxA and B) also were detected. Among the E. coli phylogroups, B2 was the most common phylogenetic group (21% of MDR-E isolates and 26% of non-MDR-E isolates), followed by A (14% and 12%), B1 (9% and 7%), D (3% and 3%), F (3% and 3%) and E (2% and 2%). This study highlights the high frequency of ESBL producers and the emergence of carbapenemase-producers among Enterobacterales causing community-acquired UTIs in Djibouti.

Clonal groups of extended-spectrum β-lactamase and biofilm producing uropathogenic Escherichia coli in Iran

Pathogenicity of a bacterium is affected by the social characteristics of the population and environmental factors. The ability of biofilm formation among β-lactamase-producing uropathogenic Escherichia coli (UPEC) could facilitate the exchange of antibiotic-resistance genes, which resulted in widespread dissemination of antibacterial drug resistance. We investigated the prevalence of biofilm and β-lactamase producing UPECs among patients with urinary tract infection (UTI) in two cities with different demographics and climates in Iran. A total of 265 E. coli was isolated from patients with UTIs from two referral hospitals (n = 191) and two outpatient clinics (n = 74) in Isfahan and Zahedan, Iran. Production of curli and cellulose, and, biofilm formation was investigated using Congo red agar and microtiter plate methods, respectively. Biofilm producing (BFP) isolates (n = 107) were further characterized using rep-PCR, antimicrobial susceptibility testing and extended-spectrum β-lactamase (ESBL)/AmpC phenotypic production. Isolates were also screened for the presence of carbapenemase, ESBL and AmpC genes using multiplex PCR.   High diversity was found among BFP strains in both cities, with 58% strains producing ESBL and 21% producing AmpC. ESBL (98%), AmpC (50%) and carbapenemase genes (40%) were identified in BFP strains with ESBL-positive phenotype, respectively. The prevalence of BFP strains, antibiotic resistance and β-lactamase genes in Zahedan, a low socioeconomic city with a warm climate, was significantly higher than that of Isfahan. High prevalence of biofilm and β-lactamase producing UPEC strains among strains from Zahedan suggests that socioeconomic status and environmental factors might have a role in pathogenicity of the strains.

Virulence genes, phylogenetic analysis, and antimicrobial resistance of Escherichia coli isolated from urinary tract infection in hospitalized patients and outpatients

Uropathogenic Escherichia coli (UPEC) strains are the most common cause of urinary tract infection (UTI) in hospitalized and community patients. The aim was to compare the genetic characteristics of E. coli isolated from inpatients (IPs) and outpatients (OPs) with UTI regarding their phylogenies, virulence traits, and resistance trends. In this cross-sectional study, 130 epidemiologically unrelated E. coli isolates were collected from patients with UTI. Extended-spectrum beta-lactamase (ESBL) production was detected by the combination disk method. UPEC and intestinal pathogenic E. coli (IPEC) virulence genes were detected by polymerase chain reaction. The isolates were analyzed for phylogenetic grouping. A P value of < 0.05 was considered significant. Of the 130 isolates, 62.3% were from OPs and 37.7% from IPs. About 35.8% of the OPs and 49% of the IPs were ESBL positive. Moreover, 56.8% of the OPs and 59.2% of the IPs were positive for UPEC virulence genes. Notably, 50% of the isolates from each group exhibited IPEC virulence properties. The predominant phylogroup was B2 (43.2% in the OPs and 40.8% in the IPs). No significant difference was found between the IP and OP isolates (P > 0.05). Our results may indicate that consideration should also be given to hygienic standards in the community. The marked genetic plasticity of E. coli has allowed the emergence of strains showing arrays of genes from different pathotypes. Characterization of E. coli isolates in different areas may guide the selection of effective infection control strategies.

Molecular Characterization of Clinical Carbapenem-Resistant Enterobacteriaceae Isolates from Sétif, Algeria

This study aimed to determine the incidence and the molecular mechanisms of carbapenem-resistant Enterobacteriaceae in patients from the Sétif University Hospital, Algeria. Nonduplicate clinical bacterial isolates recovered from patients attending the University Hospital of Sétif were collected between April and October 2018. Species identification was performed by MALDI-TOF/MS (matrix-assisted laser desorption ionization-time of flight mass spectrometry) method. The susceptibility of the isolates to carbapenems was determined using the disc diffusion method. The carbapenem resistant isolates were screened for the presence of common carbapenemase genes (bla_KPC, bla_OXA-48, bla_VIM, bla_IMP, and bla_NDM) and extended-spectrum β-lactamase (bla_CTX, bla_TEM, and bla_SHV) using PCR and sequencing technique. A total of 123 nonrepetitive Enterobacteriaceae isolates were obtained. Klebsiella pneumoniae (n = 52/42.28%), Escherichia coli (n = 24/19.51%), and Enterobacter cloacae (n = 19/15.45%) were the most prevalent species. The Carba-NP test showed that 6 out of 123 isolates carried carbapenemase enzymes. OXA-48 was found in five isolates (four K. pneumoniae and one E. coli) and NDM-5 in one E. cloacae isolate. We reported for the first time in Algeria the presence of NDM-5 carbapenemase enzyme in a clinical E. cloacae isolate.

Molecular epidemiology of blaCTX-M gene-producing uropathogenic Escherichia coli among Iranian kidney transplant patients: clonal dissemination of CC131 and CC10

Background

This study aimed to investigate the phylogenetic characterization and virulence traits of uropathogenic Escherichia coli (UPEC) isolated from kidney transplant patients (KTPs) as well as non-KTPs and analyze the clonal distribution of Extended spectrum β-lactamases (ESBLs)-producing UPEC containing bla_CTX-M gene.

Methods

To this end, we determined virulence marker and the phylogenetic characterization of UPEC in non-KTPs (n = 65) and KTPs (n = 46). The non-KTPs were considered the control group of the study. Also, according to the Achtman scheme, we performed multilocus sequence typing to assess the relationship between twenty-nine of ESBL-producing isolates containing bla_CTX-M gene.

Results

According to the results of PCR assay, the prevalence of virulence factor genes ranged from 0% (cnf and papG III) to 93.7% (fimH). Also, KTP isolates significantly differed from non-KTP isolates only in terms of the prevalence of pap GI elements. Moreover, the most frequent UPEC isolates were in phylogenetic group B₂, followed by group D (18.9%), and group A (13.5%). Furthermore, except for phylogenetic group C, there was no significant correlation between phylogenetic distribution in KTPs and non-KTPs. Additionally, MLST analysis of bla_CTX-M carrying isolates identified 18 unique sequence types (ST) the most common of which was ST131 (24.1%), followed by ST1193 (10.3%), while fourteen STs were detected only once.

Conclusions

The results further revealed significant differences between the UPEC isolates from KTPs and non-KTPs regarding the phylogroups C and PAI gene. Based on MLST analysis, we also observed a relatively high diversity in UPEC isolates obtained from KTPs and non-KTPs. Moreover, clonal complex (CC) 131 and ST131 were found to be the most prevalent clones and ST types, respectively. Besides, for the first time, ST8503 were reported in KTPs. These results suggested regular studies on characterization of UPEC isolates among KTPs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12941-021-00470-7.

Prevalence and Characterization of Extended-Spectrum Beta-Lactamase-Producing Enterobacteriaceae in Major Hospitals in Gabon

In Gabon, few data exist on extended-spectrum beta-lactamases-producing Enterobacteriaceae (ESBL-PE). This study investigated ESBL-PE prevalence and the associated resistance genes in clinical samples (n = 5,956) and anal swabs (n = 78) analyzed in eight hospitals and a medical analysis laboratory in Gabon from January 2016 to March 2018. Matrix-Assisted Laser Desorption Ionization-Time Of Flight (MALDI-TOF) mass spectrometry analysis identified 790 Enterobacteriaceae isolates (n = 712 clinical samples and n = 78 fecal samples). ESBL-PE prevalence (Müller-Hinton agar disk diffusion method and double-disk synergy test) was 11.8% (84/712) in clinical samples (15.5% from inpatients and 7.1% from outpatients; p < 0.05) and 16.7% (13/78) in carriage isolates. Most ESBL-PE were isolated from urine samples (46/84). In clinical and carriage ESBL-PE isolates, Escherichia coli was predominant (42.8% and 61.5%; phylogroups A, B1, B2, and D), followed by Klebsiella pneumoniae (41.7% and 23.1%). Multiplex PCR and bi-directional sequencing showed that CTX-M group 1 (blaCTX-M-15) was predominant in clinical and carriage ESBL-PE (94% and 92.3%) among which 85.7% and 92.3% also harbored one to three β-lactamase-encoding genes (blaTEM-1, blaOXA-1, or blaSHV-1). Resistance genes were detected in all hospitals in Gabon. ESBL-PE prevalence in Gabon has not reached alarming levels yet, but corrective and monitoring measures are needed to curb their emergence.

Retrospective Analysis on Antimicrobial Resistance Trends and Prevalence of β-lactamases in Escherichia coli and ESKAPE Pathogens Isolated from Arabian Patients during 2000-2020

The production of diverse and extended spectrum β-lactamases among Escherichia coli and ESKAPE pathogens is a growing threat to clinicians and public health. We aim to provide a comprehensive analysis of evolving trends of antimicrobial resistance and β-lactamases among E. coli and ESKAPE pathogens (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acine to bacter baumannii, Pseudomonas aeruginosa, and Enterobacter species) in the Arabian region. A systematic review was conducted in Medline PubMed on papers published between January 2000 and February 2020 on countries in the Arab region showing different antibiotic resistance among E. coli and ESKAPE pathogens. A total of n = 119,144 clinical isolates were evaluated for antimicrobial resistance in 19 Arab countries. Among these clinical isolates, 74,039 belonged to E. coli and ESKAPE pathogen. Distribution of antibiotic resistance among E. coli and ESKAPE pathogens indicated that E. coli (n = 32,038) was the predominant pathogen followed by K. pneumoniae (n = 17,128), P. aeruginosa (n = 11,074), methicillin-resistant S. aureus (MRSA, n = 4370), A. baumannii (n = 3485) and Enterobacter spp. (n = 1574). There were no reports demonstrating Enterococcus faecium producing β-lactamase. Analyses revealed 19 out of 22 countries reported occurrence of ESBL (Extended-Spectrum β-Lactamase) producing E. coli and ESKAPE pathogens. The present study showed significantly increased resistance rates to various antimicrobial agents over the last 20 years; for instance, cephalosporin resistance increased from 37 to 89.5%, fluoroquinolones from 46.8 to 70.3%, aminoglycosides from 40.2 to 64.4%, mono-bactams from 30.6 to 73.6% and carbapenems from 30.5 to 64.4%. An average of 36.9% of the total isolates were reported to have ESBL phenotype during 2000 to 2020. Molecular analyses showed that among ESBLs and Class A and Class D β-lactamases, bla_CTX-M and bla_OXA have higher prevalence rates of 57% and 52.7%, respectively. Among Class B β-lactamases, few incidences of bla_VIM 27.7% and bla_NDM 26.3% were encountered in the Arab region. Conclusion: This review highlights a significant increase in resistance to various classes of antibiotics, including cephalosporins, β-lactam and β-lactamase inhibitor combinations, carbapenems, aminoglycosides and quinolones among E. coli and ESKAPE pathogens in the Arab region.

First detection of an OXA-48-producing Enterobacter cloacae isolate from currency coins in Algeria

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First report of bla_OXA-48 gene in enterobacterial strain isolated from coins.

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Coins as a reservoir of carbapenem-resistant Enterobacteriaceae.

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First detection of CTX-M-27-producing Raoultella ornithinolytica from money.

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First detection of CTX-M-14-producing Escherichia coli from money.

Objectives

The aim of this study was to screen for the presence of β-lactamase-producing Gram-negative bacteria (GNB) from Algerian currency collected from food vendors in Batna city, Algeria.

Methods

During two periods (May 2018 and March–April 2019), a total of 408 coins and currency notes of different denominations of Algerian Dinar were randomly recovered from several food vendors. Samples were subjected to selective isolation of extended-spectrum cephalosporin- and carbapenem-resistant GNB. Bacterial species identification was performed using matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF/MS). Antibiotic susceptibility testing was performed by the disk diffusion method. Carbapenemase and extended-spectrum β-lactamase (ESBL) genes were searched for by real-time PCR, standard PCR and sequencing. The clonal relationship of carbapenemase-producing isolates was investigated by multilocus sequence typing (MLST). The transferability of the detected carbapenemase-encoding gene was verified by conjugation experiments.

Results

Twelve cefotaxime- and/or carbapenem-resistant strains were isolated in this study and were identified as Enterobacter cloacae, Raoultella ornithinolytica, Citrobacter freundii, Escherichia coli, Pseudomonas aeruginosa, Pseudomonas libanensis and Pseudomonas stutzeri. The bla_OXA-48 gene was detected in only one E. cloacae strain belonging to sequence type 108 (ST108), whilst the two R. ornithinolytica isolates harboured bla_CTX-M-27 and one E. coli strain carried bla_CTX-M-14. The detected bla_OXA-48 gene was transferable by conjugation.

Conclusions

We report for the first time the detection of an OXA-48-producing E. cloacae isolate from money. This calls for consciousness development on the potential risks associated with poor handling of currency.

Characterization of Extended-Spectrum β-Lactamase-Producing Uropathogenic Escherichia coli Among Iranian Kidney Transplant Patients

Introduction

The aim of this study was to investigate the antimicrobial susceptibility pattern and the presence of ESBLs among the uropathogenic Escherichia coli (UPEC) isolated from kidney transplant patients (KTP) and community-acquired urinary tract infections (UTIs) using phenotypic and molecular methods.

Materials and Methods

A total of 111 pure cultures of UPEC isolates were collected from 65 and 46 of non-KTP and KTPs with UTIs. The pattern and ESBL production of the strains were evaluated. PCR reaction to detect the presence of bla _SHV, bla _TEM, and bla _CTX-M genes was performed.

Results

The results revealed that most of UPEC isolates obtained from KTPs and control group were resistant to trimethoprim/sulfamethoxazole (84.8% vs 46.2%), while carbapenems (100% sensitivity) were the most effective against UPEC isolates. ESBL-producing strains were significantly more frequent in KTPs compared with control group (43.5% vs 23.1%, P = 0.021). The molecular results revealed that 53.2% (59/111), 45% (50/111), and 5.4% (6/111) of isolates harbored bla _CTX-M, bla _TEM, and bla _SHV genes, respectively. Of the genes investigated, bla _CTX-M and bla _TEM genes were significantly higher among KTP than the control group.

Conclusion

Our results showed a high proportion of multidrug-resistant and ESBL-producing isolates, which most of them harbor blaCTX-M. A significant high co-resistance to different classes of antibiotics was reported from ESBL-producing UPEC from KTPs, which remains a serious clinical challenge.

Extended-spectrum beta-lactamases and plasmid diversity in urinary isolates of Escherichia coli in Croatia: a nation-wide, multicentric, retrospective study

In recent years, a dramatic increase in the prevalence of Escherichia coli strains producing extended-spectrum β-lactamases (ESBLs) has been observed - both in the community and in healthcare settings. This multicentric study aimed to characterize ESBLs produced by E. coli isolates causing hospital-onset and community urinary tract infections, as well as to compare their antimicrobial sensitivity patterns, β-lactamase content and plasmid types. Phenotypic tests for the detection of ESBLs and plasmid-mediated AmpC β-lactamases were initially pursued, followed by molecular detection of resistance genes, plasmid characterization, genotyping with pulsed-field gel electrophoresis and whole genome sequencing (WGS). The isolates exhibited high level of resistance to expanded-spectrum cephalosporins (ESC) and carried CTX-M (cefotaximase-Munich) or TEM (Temoniera) β-lactamases. All six representative isolates subjected to WGS belonged to the widespread clone ST131. In conclusion, our study demonstrated dissemination of group 1 CTX-M positive E. coli in different geographic regions of Croatia, but also different components of the health care systems (hospitals, nursing homes and the community) and confirmed the switch from SHV-2 (suphydril variant) and SHV-5 ESBLs to the nation-wide predominance of group 1 CTX-M β-lactamases. Different plasmids were shown to be associated with the dissemination of bla_CTX-M genes in different geographic regions of Croatia.

Chemical Composition and Antibacterial Activity of Essential Oils from the Algerian Endemic Origanum glandulosum Desf. against Multidrug-Resistant Uropathogenic E. coli Isolates

Antibiotics are becoming ineffective against resistant bacteria. The use of essential oils (EOs) may constitute an alternative solution to fight against multidrug-resistant bacteria. This study aims to determine the chemical composition of EOs from five populations of the endemic Algerian Origanum glandulosum Desf. and to investigate their potential antibacterial activity against multidrug-resistant uropathogenic E. coli strains. The EOs were obtained by hydrodistillation and their composition was investigated by gas chromatography/mass spectrometry (GC/MS). The antibacterial activity was evaluated by the disc diffusion method against eight E. coli strains (six uropathogenic resistant and two referenced susceptible strains). Minimum inhibitory and bactericidal concentrations (MIC/MBC) were obtained by the broth microdilution method. The main EO components were thymol (15.2–56.4%), carvacrol (2.8–59.6%), γ-terpinene (9.9–21.8%) and p-cymene (8.5–13.9%). The antibacterial tests showed that all the EOs were active against all the strains, including the multidrug-resistant strains. The EO from the Bordj location, which contained the highest amount of carvacrol (59.6%), showed the highest antibacterial activity (inhibition diameters from 12 to 24.5 mm at a dilution of 1/10). To our knowledge, this is the first description of the activity of O. glandulosum EOs against resistant uropathogenic strains. Our study suggests that O. glandulosum EO could be used in some clinical situations to treat or prevent infections (e.g., urinary tract infections) with multidrug-resistant strains.

Development of real-time PCR assay allowed describing the first clinical Klebsiella pneumoniae isolate harboring plasmid-mediated colistin resistance mcr-8 gene in Algeria

OBJECTIVES

We aimed to develop here a specific real-time PCR assay with TaqMan® probe to detect efficiently bacterial strains harboring the new plasmid mediated-colistin resistance mcr-8 gene.

METHODS

Specific primers and probe for mcr-8 gene were designed from sequences alignment of all mcr genes variants. Specificity of the designed primers and probe were first checked par BlastN analysis and by in silico PCR. The analytical sensitivity and specificity tests were performed in vitro on a panel of 290 genomic DNA of Gram-negative bacteria and 250 metagenomic DNA from human stool samples. Whole genome sequencing (WGS) was performed here using MiSeq technology.

RESULTS

Designed primers and probe were 100% specific tomcr-8 gene by BlastN and in silico PCR analysis. Real-time PCR screening of a collection of clinical isolates resulted to one positive Klebsiella pneumoniae isolate (KP95). WGS confirmed that this isolate harbored the mcr-8 gene and other resistance genes such as bla_OXA-48, bla_CTX-M-15 β-lactamases. Our real-time PCR was highly sensitive on a 10-fold dilution serie from a calibrated inoculum at 10⁸ CFU/mL with a limit of detection at 55 CFU/mL.

CONCLUSION

To the best of our knowledge, we propose here, the first real-time PCR assay targeting mcr-8 gene with high specificity and sensitivity, able to detect mcr-8 gene in less than 2 h from any DNA sample. This real-time PCR assay allowed the first description of a clinical K. pneumoniae strain harboring the mcr-8 gene in Algeria.