MAMA-PCR assay for the detection of point mutations associated with high-level erythromycin resistance in Campylobacter jejuni and Campylobacter coli strains

Spatiotemporal variations in the occurrence of Campylobacter species in the Bloukrans and Swartkops rivers, Eastern Cape, South Africa

An increase in the incidence of Campylobacter species in rivers raises concerns on the safety of river water for humans who get exposed to river water. This study examines the spatiotemporal dynamics of Campylobacter species in the Bloukrans and Swartkops rivers, analysing patterns of its occurrence in relation to meteorological conditions, physicochemical parameters, seasons, and sampling sites. Physico-chemical parameters and meteorological conditions were measured during water sampling from various sites along the rivers over a year, while Polymerase Chain Reaction (PCR) was utilised to detect Campylobacter genus-specific genes and selected antibiotic-resistant genes. Campylobacter was detected in 66.67% (Bloukrans River) and 58.33% (Swartkops River). In the Bloukrans River, multi-drug resistance genes cmeA (20%), cmeB (65%), cmeC (10%), were detected while and tetO was detected at 70%. In the Swartkops River, the corresponding prevalence were 28%, 66.67%, 28.56%, and 76%. The study indicates that sampling season did not significantly impact Campylobacter prevalence. However, variation in Campylobacter occurrence exists among different sites along the rivers, reflecting the influence of site proximity to potential contamination sources. The study suggests that Campylobacter infection may be endemic in South Africa, with rivers serving as potential sources of exposure to humans, thereby contributing to the epidemiology of campylobacteriosis.

The characterization and correlation between the phenotypic and genotypic resistance of Campylobacter spp. isolates from commercial broilers and native chickens in the south of Thailand

RESEARCH HIGHLIGHTS

High Campylobacter prevalence in chickens; C. jejuni more prevalent than C. coli.Susceptibility to macrolides but resistance to quinolones/tetracyclines in isolates.Homogeneous resistance patterns within farms; higher in broilers than in native birds.Partial association between phenotypic and genotypic resistance among isolates.

Genotypic characterization, antimicrobial susceptibility and virulence determinants of Campylobacter jejuni and Campylobacter coli isolated from pastured poultry farms

Aim

Campylobacter is the leading bacterial pathogen that causes foodborne illnesses worldwide. Pasture farming is regarded as an important source of agricultural production for small farming communities. Consumer preference for pasture-raised animal products has increased; however, there is a paucity of information on the microbiological quality of pasture-raised poultry products. The purpose of this study was to explore genetic relatedness of thermophilic Campylobacter isolates, to assess antibiotic resistance phenotypically and genotypically, and to screen the presence of virulence determinants of Campylobacter isolates from pasture-raised poultry farms from southeastern United States.

Methods

Ninety-seven Campylobacter isolates previously identified by Q7 BAX® System Real-Time PCR were genotyped by multilocus sequence typing (MLST). Campylobacter isolates were then evaluated for their phenotypic antimicrobial susceptibility against nine antimicrobial agents using Sensititre plates. Additionally, Campylobacter isolates were tested for the presence of antimicrobial resistance-associated elements. Furthermore, Campylobacter isolates were screened for the presence of 13 genes encoding putative virulence factors by PCR. These included genes involved in motility (flaA and flhA), adhesion and colonization (cadF, docC, racR, and virB11), toxin production (cdtA, cdtB, cdtC, wlaN, and ceuE) and invasion (ciaB and iamA).

Results

Among 97 Campylobacter isolates, Campylobacter jejuni (n = 79) and Campylobacter coli (n = 18) were identified. By MLST, C. jejuni isolates were assigned to seven clonal complexes. Among them, ST-353, ST-607 and ST-21 were the most common STs recognized. All C. coli (n = 18) isolates were included in CC-828. Interestingly, eight STs identified were not belonging any previous identified clonal complex. Campylobacter isolates displayed a high resistance rate against tetracycline (81.4%), while a low rate of resistance was observed against macrolides (azithromycin and erythromycin), quinolones and fluoroquinolones (nalidixic acid and ciprofloxacin), aminoglycosides (gentamicin), ketolide (telithromycin), amphenicol (florfenicol) and lincomycin (clindamycin). Thirteen isolates (13.54%) were pan-susceptible to all tested antibiotics, while nine isolates were multi-antimicrobial resistant (MAR; resist to three or more antimicrobial classes). Interestingly, there were no isolates resistant to all antimicrobial classes. Thr86Ile mutation was identified in all quinolones resistant strains. Erythromycin encoding gene (ermB) was identified in 75% of erythromycin resistant isolates. The A2075 mutation was detected in one erythromycin resistant strain, while A2074 could not be identified. The tetO gene was identified in 93.7% of tetracycline resistant isolates and six tetracycline susceptible isolates. In conclusion, the results of this study revealed that Campylobacter isolates from pasture-raised poultry farms showed the ST relatedness to Campylobacter isolates commonly associated with humans, indicating pasture-raised broiler flocks, similar to conventionally-reared broiler flocks, as a potential vector for antibiotic-resistant and pathogenic strains of thermophilic Campylobacter to humans.

Campylobacter jejuni and Campylobacter coli in human stool samples: antibiotic resistance profiles, putative virulence determinants and molecular characterization of the isolates

Campylobacters, especially C. jejuni and C. coli, have become one of the leading causes of acute gastroenteritis in humans worldwide in recent years. We aimed to investigate the presence, antimicrobial resistance, putative virulence genes, and molecular characterization of C. jejuni and C. coli recovered from human acute gastroenteritis cases in the study. In the study, suspected Campylobacter spp. isolates were obtained in 43 (5%) feces samples collected from a total of 850 patients who applied to the Erciyes University Medical Faculty acute clinic between March 2019 and February 2020. As a result of the phenotypic tests, these isolates were determined to be Campylobacter spp. According to the multiplex PCR, 33 of 43 Campylobacter spp. isolates were identified as C. jejuni (76%) and ten isolates were as C. coli (24%). In the disc diffusion test, the highest resistance rate was found in the trimethoprim/sulfamethoxazole (90.1%) and ciprofloxacin (90.1%), and the lowest rate was found in the amoxicillin-clavulanic acid (9.3%). In Campylobacter spp. isolates, the virulence genes cdtA, virB11, cdtB, cadF, iam, ceu, and flaA were found to be positive at rates of 26 (60%), 28 (65.6%), 13 (30%), 4 (9%), 27 (62%), 17 (39%), and 7 (16%), respectively. However, the cdtC gene was not detected in any of the isolates. The study searched tetO gene to examine the genetic aspect of tetracycline resistance, which was found in all Campylobacter spp. isolates. In the PCR reactions to investigate A2074C and A2075G mutations of macrolide resistance, it was determined as 7 (16%) and 21 (48%) of the isolates. To detect quinolone resistance, the rates of quinolone resistance-determining regions (QRDR) were 20 (45.4%) and the gyrA gene mutations in the mismatch amplification mutation assay PCR (MAMA-PCR), were 19 (43.1%) of isolates. In addition, the quinolone resistance gene (qnr) carried by plasmid in Campylobacter isolates was not found in the study. BlaOXA-61 and CmeB (multi-drug efflux pump) genes were detected as 28 (63.6%) and 30 (68.1), respectively. The Enterobacterial Repetitive Intergenic Consensus PCR (ERIC-PCR) used for typing the isolates revealed that the band profiles obtained from the isolates were different. In conclusion, this was a very comprehensive study revealing the presence of antibiotic-resistant C. jejuni and C. coli with various virulence genes in patients admitted to a university hospital with acute gastroenteritis. This is of utmost significance for public health. Since campylobacteria are foodborne, zoonotic pathogens and transmission occurs mostly through food. People should have detailed information about the transmission routes of campylobacteria and risky foods. In addition, staff, food processors and caterers, should be trained in hygiene.

SVR-flaA typing of erythromycin- and ciprofloxacin-resistant Campylobacter jejuni strains isolated from poultry slaughterhouses in southern Brazil

The emergence of fluoroquinolone and macrolide resistance in C. jejuni, a recognized zoonotic pathogen, has increased worldwide. This study aimed to investigate phenotypic resistance to ciprofloxacin and erythromycin, the molecular mechanisms involved, and the strain of C. jejuni isolated from broiler carcasses. Eighty C. jejuni isolates from broiler carcasses in southern Brazil were investigated for their susceptibility to ciprofloxacin and erythromycin at minimal inhibitory concentrations. Mismatch amplification mutation assay-polymerase chain reaction (MAMA-PCR) was performed to detect substitutions of Thr-86-Ile, A2074C, and A2075G of domain V in the 23S rRNA. The presence of ermB gene and CmeABC operon were investigated by PCR. DNA sequencing was used to detect substitutions in the L4 and L22 proteins of the erythromycin-resistant strains. The Short Variable Region (SVR) of flaA was used to type all the strains resistant to both antimicrobials. Ciprofloxacin and erythromycin resistance were detected in 81.25% and 30.00% of the strains, respectively, and minimal inhibitory concentration values ranged from ≤ 0.125 to 64 µg/mL for ciprofloxacin and 0.5 to > 128 µg/mL for erythromycin. The Thr-86-Ile mutation in gyrA was observed in 100% of the ciprofloxacin-resistant strains. Mutations in both the A2074C and A2075G positions of 23S rRNA were observed in 62.5% of the erythromycin-resistant strains, while 37.5% had only the mutation A2075G. None of the strains harbored CmeABC operon, and ermB was not detected. Using DNA sequencing, the amino acid substitution T177S was detected in L4, and substitutions I65V, A103V, and S109A were detected in L22. Twelve flaA-SVR alleles were identified among the strains, with the most common SVR-flaA allele, type 287, covering 31.03% of ciprofloxacin- and erythromycin-resistant isolates. The present study revealed a high incidence and high levels of resistance to ciprofloxacin and erythromycin, as well as broad molecular diversity in C. jejuni isolates from broiler carcasses.

Persistence of Campylobacter spp. in Poultry Flocks after Disinfection, Virulence, and Antimicrobial Resistance Traits of Recovered Isolates

To investigate the persistence risk of Campylobacter spp. in poultry farms, and to study the virulence and antimicrobial resistance characteristics in the recovered strains, we collected 362 samples from breeding hen flocks, before and after disinfection. The virulence factors were investigated by targeting the genes; flaA, cadF, racR, virB11, pldA, dnaJ, cdtA, cdtB, cdtC, ciaB, wlaN, cgtB, and ceuE by PCR. Antimicrobial susceptibility was tested and genes encoding antibiotic resistance were investigated by PCR and MAMA-PCR. Among the analyzed samples, 167 (46.13%) were positive for Campylobacter. They were detected in 38.7% (38/98) and 3% (3/98) of environment samples before and after disinfection, respectively, and in 126 (75.9%) out of 166 feces samples. In total, 78 C. jejuni and 89 C. coli isolates were identified and further studied. All isolates were resistant to macrolids, tetracycline, quinolones, and chloramphenicol. However, lower rates were observed for beta-lactams [ampicillin (62.87%), amoxicillin-clavulanic acid (47.3%)] and gentamicin (0.6%). The tet(O) and the cmeB genes were detected in 90% of resistant isolates. The bla_OXA-61 gene and the specific mutations in the 23S rRNA were detected in 87% and 73.5% of isolates, respectively. The A2075G and the Thr-86-Ile mutations were detected in 85% and 73.5% of macrolide and quinolone-resistant isolates, respectively. All isolates carried the flaA, cadF, CiaB, cdtA, cdtB, and cdtC genes. The virB11, pldA, and racR genes were frequent in both C. jejuni (89%, 89%, and 90%, respectively) and C. coli (89%, 84%, and 90%). Our findings highlight the high occurrence of Campylobacter strains exhibiting antimicrobial resistance with potential virulence traits in the avian environment. Thus, the improvement of biosecurity measures in poultry farms is essential to control bacterial infection persistence and to prevent the spread of virulent and resistant strains.

Distribution of virulence and antibiotic resistance genes in Campylobacter jejuni and Campylobacter coli isolated from broiler chickens in Tunisia

BACKGROUND

Thermo-tolerant Campylobacter species are the major cause of foodborne diseases worldwide. This study aimed to evaluate the prevalence of virulence genes and antibiotic resistance determinants in Campylobacter jejuni and Campylobacter coli isolates, and to investigate the relationship between these two traits.

METHODS

A total of 132 Campylobacter isolates from poultry were tested for the presence of 13 virulence genes; flaA, cadF, racR, virB11, pldA, dnaJ, cdtA, cdtB, cdtC, ciaB, wlaN, cgtB and ceuE. The mechanisms underlying antibiotic resistance phenotypes were also studied by PCR and MAMA-PCR.

RESULTS

PCR results revealed the presence of antimicrobial resistance genes in C. jejuni and C. coli as follows: cmeB (80% and 100%), tet(O) (100% and 80%), and the bla_OXA-61 (81% and 93%), respectively. None of these strains harbored the aphA-3 gene. The Thr-86-Ile mutation associated with resistance to quinolones was found in 90% of C. jejuni and 80% of C. coli isolates. While the A2075G and A2074C mutations linked to the erythromycin resistance were detected in 100% of both species. Virulence genes were prevalent and ranged from 40 to 100%. A positive relationship was revealed between cadF, racR, and ciaB genes and resistance to ampicillin, amoxicillin/clavulanic acid, chloramphenicol, and nalidixic acid, in C. jejuni. However, no association was observed for C. coli isolated strains.

CONCLUSION

This study provides for the first time an overview of antibiotic resistance mechanisms and pathogenic profiles of Campylobacter isolates, which emphasizes the potential risk for consumer health.

Relationships between Virulence Genes and Antibiotic Resistance Phenotypes/Genotypes in Campylobacter spp. Isolated from Layer Hens and Eggs in the North of Tunisia: Statistical and Computational Insights

Globally, Campylobacter is a significant contributor to gastroenteritis. Efficient pathogens are qualified by their virulence power, resistance to antibiotics and epidemic spread. However, the correlation between antimicrobial resistance (AR) and the pathogenicity power of pathogens is complex and poorly understood. In this study, we aimed to investigate genes encoding virulence and AR mechanisms in 177 Campylobacter isolates collected from layer hens and eggs in Tunisia and to assess associations between AR and virulence characteristics. Virulotyping was determined by searching 13 virulence genes and AR-encoding genes were investigated by PCR and MAMA-PCR. The following genes were detected in C. jejuni and C. coli isolates: tet(O) (100%/100%), bla_OXA-61 (18.82%/6.25%), and cmeB (100%/100%). All quinolone-resistant isolates harbored the Thr-86-Ile substitution in GyrA. Both the A2074C and A2075G mutations in 23S rRNA were found in all erythromycin-resistant isolates; however, the erm(B) gene was detected in 48.38% and 64.15% of the C. jejuni and C. coli isolates, respectively. The machine learning algorithm Random Forest was used to determine the association of virulence genes with AR phenotypes. This analysis showed that C. jejuni virulotypes with gene clusters encompassing the racR, ceuE, virB11, and pldA genes were strongly associated with the majority of phenotypic resistance. Our findings showed high rates of AR and virulence genes among poultry Campylobacter, which is a cause of concern to human health. In addition, the correlations of specific virulence genes with AR phenotypes were established by statistical analysis.

Molecular markers associated with antimicrobial resistance and genotypes of Campylobacter jejuni and Campylobacter coli isolated from broiler and swine flocks in southeast Brazil

This study aimed to identify molecular markers associated with antimicrobial resistance and genotype isolates of Campylobacter spp. from broiler and swine flocks due to its importance to one-health. C. jejuni (n=27) and C. coli (n = 35) strains were screened for the antimicrobial genetic markers C257T in gyrA, A2074C and A2075G in 23S rRNA, CmeABC, ermB, tetO and blaOXA61 by PCR. Fifteen strains had SVR-flaA and porA genes sequenced to evaluate their genetic diversity. Among C. jejuni strains 62.96% had C257T mutation and only one strain had A2075G mutation. CmeA, cmeB, cmeC, tetO and blaOXA61 were detected respectively in 92.59%, 100%, 100%, 85.19%, 85.19% of the strains. All C. coli had C257T mutation; 48.75% had A2075G and cmeA, cmeB, cmeC, tetO, blaOXA61 were detected in 8.57%, 94.29%, 91.43%, 91.43%, 80%, respectively. Twelve porA and SVR-flaA alleles were detected, with a Simpson index of diversity value of 0.962.

Virulence Profiling, Multidrug Resistance and Molecular Mechanisms of Campylobacter Strains from Chicken Carcasses in Tunisia

Antibiotic resistance in foodborne pathogens is an emergent global health concern. The objectives of this study were to assess antimicrobial resistance (AMR) in Campylobacter isolates from chicken carcasses and to investigate the AMR molecular mechanisms as well as the presence of virulence determinants. The study was performed on 257 samples collected from abattoirs and retail shops in northeastern Tunisia. Forty-eight Campylobacter isolates were recovered and identified as C. jejuni (n = 33) and C. coli (n = 15). Antibiotic resistance was tested against eight antibiotics and high resistance rates were observed against tetracycline (100%), erythromycin (97.9%), ciprofloxacin (73%), nalidixic acid (85.4%), ampicillin (83.3%), amoxicillin/clavulanic acid (22.9%), chloramphenicol (75%), and gentamicin (27.1%). All isolates were multidrug-resistant, and 22 resistance patterns were found. All isolates were screened for AMR genes (tet(O), tet(A), tet(B), tet(L), cmeB, ermB, bla_OXA-61, and aphA-3), and for point mutations in gyrA (C257T substitution) and 23SrRNA (A2075G/A2074C) genes. All screened AMR genes, as well as the C257T and the A2075G mutations, were detected. The virulence genotypes were also determined, and all isolates carried the motility (flaA) and invasion (cadF) genes. Most of them also harbored the cdtA, cdtB, and cdtC genes, encoding the Campylobacter toxin. The screening of the cgtB and the wlaN genes, involved in Guillain-Barré Syndrome expression, revealed the presence of the cgtB in 21.2% of C. jejuni strains, whereas none of them carried the wlaN gene. Our findings highlight the emergence of Campylobacter strains simultaneously harboring several virulence and AMR determinants, which emphasizes the risk of transmission of MDR strains to humans via the food chain. Hence, controlling the dissemination of foodborne pathogens “from the farm to the fork” as well as restricting the use of antimicrobials in husbandry are mandatory to prevent the risk for consumers and to mitigate the dissemination of MDR pathogens.

Prevalence and antimicrobial resistance of Campylobacter jejuni and C. coli identified in a slaughterhouse in Argentina

The aim of this study was to evaluate the percentage of Campylobacter (C. jejuni and C. coli) from samples collected at the slaughterhouse to describe the prevalence of resistance to selected antimicrobials, and to characterize the genetic determinants. In total, from 333 samples analyzed, 31% were positive for Campylobacter. More positive samples were detected before the chiller (46%) than after the chiller (16%). C. coli (59%) was more prevalent than C. jejuni (41%). Antimicrobial resistance differences between C. jejuni and C. coli were found (p < 0.001). Multidrug resistance was found in 72% of C. coli isolates and 69% of C. jejuni isolates (p < 0.001). Most C. jejuni isolates (57%) had the three genes of the cmeABC efflux pump. The tet(O) gene and resistance-associated point mutations within both the gyrA and 23S rRNA genes were detected in 100% of C. coli isolates. On the other hand, C. jejuni only had more prevalence of the bla_OXA-61 gene than C. coli (p < 0.001), and most of the C. jejuni isolates (70–80%) had the tet(O) and gyrA point mutation. These results could contribute to knowledge about the status of thermotolerant Campylobacter resistant to antimicrobials isolated from food animals in Argentina and to develop an antimicrobial resistance surveillance system.

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From samples analyzed, 31% were positive for Campylobacter.

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More positive samples were detected before the chiller (46%) than after it (16%).

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Multidrug resistance was found in 72% of C. coli isolates and 69% of C. jejuni isolates.

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The tet(O) gene was detected in 100% of the tetracycline-, resistantC. coliisolates.

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C.jejuni only had more prevalence of the bla_OXA-61 gene than C. coli (p < 0.001).

Phenotypic and Molecular Patterns of Resistance among Campylobacter coli and Campylobacter jejuni Isolates, from Pig Farms

Simple Summary

Campylobacter spp. has been the leading cause of human diarrhea in EU since 2005. Although poultry and poultry meat are considered as the primary source of transmission of campylobacteriosis to humans, pigs can be a significant reservoir of the pathogen, as well. Moreover, the increase of antibiotic resistance in the specific pathogen, especially against fluroquinolones and macrolides is considered a significant threat for public health. The purpose of the current study was to evaluate and molecularly characterize the antimicrobial resistance of Campylobacter infection in pig farms in Greece at both phenotypic and molecular level.

Abstract

The purpose of this research was to characterize the antibiotic resistance patterns of Campylobacter spp. isolated from commercial farrow to finish farms in Greece, and analyze the relevant molecular resistance mechanisms among the resistant Campylobacter isolates. Susceptibility testing to five different classes of antibiotics was performed in 100 C. coli and 100 C. jejuni, previously isolated and identified. All isolates were found susceptible to meropenem. Very high rates of resistance were recorded for tetracyclines (84.5%), medium rates of resistance were recorded regarding quinolones (23%), and low and very low rates of resistance were identified for macrolides such as erythromycin and aminoglycosides (12% and 4%, respectively). Only 12.5% of the Campylobacter isolates displayed MDR. Regarding the molecular mechanisms of resistance, all ciprofloxacin resistant isolates hosted the mutant type Thr-86-Ile region of the quinolone resistance-determining region (QRDR) of the gyrA gene. In all erythromycin resistant isolates, the transitional mutations A2075G and A2074C in the 23S rRNA gene were only amplified. Molecular screening of tetracycline resistance genes indicated that the vast majority of Campylobacter isolates (92.3%) were positive for the tet(O) gene. In summary, these findings and especially the very high and medium rates of resistance for tetracyclines and fluroquinolones, respectively recommend that a continuous monitoring of Campylobacter isolates susceptibility in combination with the proper use of antimicrobials in livestock production is of great importance for public health.

Occurrence and antimicrobial resistance of Campylobacter isolates from broiler chicken and slaughter house environment in India

Campylobacteriosis is among the most frequently reported foodborne zoonoses. A total of 848 samples were screened for Campylobacter spp. and occurrence was found to be 8.7%, 2.3% and 1.65% in broiler cecum samples, chicken meat samples and slaughter house environment swabs, respectively. High level of antimicrobial resistance was found against tetracycline (64.1%), doxycycline (54.4%), ampicillin (46.6%), nalidixic acid (42.7%), kanamycin (35.9%), and ciprofloxacin (33.33%). Resistance to co-amoxiclav (19.4%) and erythromycin (21.4%) was less common. The MAR index of the isolates was in the range of 0.11-0.78. Multi-drug resistance was observed in 54.4% of the isolates, with 53.2% C. jejuni and 55.3% C. coli isolates found resistant against three or more classes of antimicrobials. Presence of mutations in gyrA and 23S rRNA genes was investigated, which revealed that all the fluoroquinolone resistant isolates possessed Thr-86-Ile point mutation, whereas only 68% of erythromycin resistant isolates had A2075G mutation. The tetO gene was present in 91.7% tetracycline resistant isolates and bla_OXA-61 gene was detected in 97.9% of the ampicillin resistant isolates. The occurrence of antimicrobial resistant Campylobacter spp. in broiler chicken samples and slaughter house settings is a public health risk and calls for judicial use of antimicrobials.

Identification of a Mycobacterium tuberculosis-specific gene marker for diagnosis of tuberculosis using semi-nested melt-MAMA qPCR (lprM-MAMA)

Tuberculosis (TB) is the deadliest of infectious diseases. TB diagnosis, based on sputum microscopy, culture, and nucleic acid amplification tests (NAATs) to identify its main causative agent, Mycobacterium tuberculosis (MTB), remains challenging. The current available NAATs, endorsed by World Health Organization (WHO), can differentiate MTB from some MTB complex (MTBC) members. Using bioinformatics, we identified a single nucleotide polymorphism (SNP) in lprM (Rv1970) gene that differentiate MTB from other MTBC members. A forward mismatch amplification mutation assay (MAMA) primer was designed for the targeted mutation and was used in a semi-nested melt-MAMA qPCR (lprM-MAMA). Using the optimized protocol, lprM-MAMA was positive with all MTB reference and clinical strains, and negative with other MTBC members, non-tuberculous mycobacteria (NTM) and other non-mycobacterial (NM) reference strains. The limit of detection (LOD) of lprM-MAMA was 76.29 fg. Xpert® MTB/RIF (Xpert)-positive sputum samples were also positive by lprM-MAMA, except for samples classified as having "very low" bacterial load by Xpert. Xpert-negative sputum samples were also negative by lprM-MAMA. In conclusion, lprM-MAMA demonstrated to be a useful tool for specific MTB diagnosis. Further evaluation with higher number of reference strains, including NTM and NM; and sputum samples are required to determine its potential for clinical application.

Phenotypic and molecular characterization of erythromycin resistance in Campylobacter jejuni and Campylobacter coli strains isolated from swine and broiler chickens

ABSTRACT: Campylobacter spp. is a bacterial agent that causes gastroenteritis in humans and may trigger Guillain-Barré Syndrome (GBS) and is also considered one of the main foodborne diseases in developed countries. Poultry and pigs are considered reservoirs of these microorganisms, as well as raw or undercooked by-products are often incriminated as a source of human infection. Treatment in human cases is with macrolide, such erythromycin, that inhibits the protein synthesis of the microorganism. This study aimed to isolate Campylobacter jejuni and Campylobacter coli from intestinal content samples of broiler chickens (n=20) and swine (n=30) to characterize the erythromycin resistance profile of the strains and to detect molecular mechanisms involved in this resistance. The minimum inhibitory concentration was determined by agar dilution. The Mismatch Amplification Mutation Assay-Polymerase Chain Reaction (MAMA-PCR) was performed to detect mutations at positions 2074 and 2075 of 23S rRNA region, in addition to PCR test to detect the erm(B) gene. From the intestinal content of broiler chickens, 18 strains of C. jejuni and two strains of C. coli were isolated, whereas, from swine samples, no C. jejuni strain and 14 strains of C. coli were isolated. All C. coli strains were resistant, and three C. jejuni strains from broilers chickens were characterized with intermediate resistance to erythromycin. The MIC of the strains ranged from ≤0.5mg/μL to ≥128mg/μL. All resistant strains had the A2075G mutation, and one strain with intermediate resistance had the A2075G mutation. However, the A2074C mutation and the erm(B) gene were not detected. High resistance levels were detected in C. coli strains isolated from swine. The MAMA-PCR is a practical tool for detecting the erythromycin resistance in Campylobacter strains.

Antimicrobial resistance patterns and molecular resistance markers of Campylobacter jejuni isolates from human diarrheal cases

The aim of this study is to characterize the antimicrobial resistance of Campylobacter jejuni recovered from diarrheal patients in Belgium, focusing on the genetic diversity of resistant strains and underlying molecular mechanisms of resistance among Campylobacter jejuni resistant strains isolated from diarrheal patients in Belgium. Susceptibility profile of 199 clinical C. jejuni isolates was determined by minimum inhibitory concentrations against six commonly-used antibiotics (ciprofloxacin, nalidixic acid, tetracycline, streptomycin, gentamicin, and erythromycin). High rates of resistance were observed against nalidixic acid (56.3%), ciprofloxacin (55.8%) and tetracycline (49.7%); these rates were similar to those obtained from different national reports in broilers intended for human consumption. Alternatively, lower resistance rates to streptomycin (4.5%) and erythromycin (2%), and absolute sensitivity to gentamicin were observed. C. jejuni isolates resistant to tetracycline or quinolones (ciprofloxacin and/or nalidixic acid) were screened for the presence of the tetO gene and the C257T mutation in the quinolone resistance determining region (QRDR) of the gyrase gene gyrA, respectively. Interestingly, some of the isolates that displayed phenotypic resistance to these antimicrobials lacked the corresponding genetic determinants. Among erythromycin-resistant isolates, a diverse array of potential molecular resistance mechanisms was investigated, including the presence of ermB and mutations in the 23S rRNA gene, the rplD and rplV ribosomal genes, and the regulatory region of the cmeABC operon. Two of the four erythromycin-resistant isolates harboured the A2075G transition mutation in the 23S rRNA gene; one of these isolates exhibited further mutations in rplD, rplV and in the cmeABC regulatory region. This study expands the current understanding of how different genetic determinants and particular clones shape the epidemiology of antimicrobial resistance in C. jejuni in Belgium. It also reveals many questions in need of further investigation, such as the role of other undetermined molecular mechanisms that may potentially contribute to the antimicrobial resistance of Campylobacter.

Characterization and Phylogenetic Analysis of Campylobacter Species Isolated from Paediatric Stool and Water Samples in the Northwest Province, South Africa

Antibiotic-resistant Campylobacter could adversely affect treatment outcomes, especially in children. We investigated the antibiotic susceptibility profiles, virulence potentials and genetic relatedness of Campylobacter spp. from paediatric and water samples in the North West Province, South Africa. Overall, 237 human and 20 water isolates were identified using culture and real-time polymerase chain reaction (PCR). The antibiotic susceptibility profiles were determined using the disk diffusion method. Gradient strips were used to determine the minimum inhibitory concentration of each antibiotic. Antibiotic resistance (gryA, tetO and 23S rRNA 2075G and 2074C) and virulence (cadF and ciaB) genes were also investigated using PCR. A phylogenetic tree to ascertain the clonality between water and clinical isolates was constructed using MEGA 7. Overall, 95% (water) and 64.7% (human) of the isolates were resistant to at least one antibiotic tested. The highest resistance was against clarithromycin (95%) for water and ampicillin (60.7%) for human isolates. The 23S rRNA 2075G/2074C mutation was the most expressed resistance gene. Phylogenetic reconstruction revealed eight intermixed clades within water and human Campylobacter isolates. This study suggests the possible circulation of potentially pathogenic antibiotic-resistant Campylobacter in the Northwest Province, South Africa with drinking water being a possible vector for disease transmission in this area.

Phylogenetic Diversity and Antimicrobial Resistance of Campylobacter coli from Humans and Animals in Japan

The phylogenetic diversity and antimicrobial resistance (AMR) of Campylobacter coli from humans and animals in Japan between 2008 and 2014 were investigated. A total of 338 foodborne campylobacterioses were reported in Osaka, and C. coli was isolated from 38 cases (11.2%). In the present study, 119 C. coli strains (42 from humans, 25 each from poultry, cattle, and swine, and 2 from wild mallard) were examined by multilocus sequence typing (MLST). MLST assigned 36 sequence types (STs), including 14 novel STs; all human strains and 91% of animal strains (70/77) were assigned to the ST-828 clonal complex. The predominant human ST was ST-860 (18/42, 43%), followed by ST-1068 (8/42, 19%); these STs were also predominant in poultry (ST-860, 9/25, 36%) and cattle (ST-1068, 18/25, 72%). ST-1562 was only predominant in swine (11/25, 44.0%). Swine strains showed the greatest resistance to erythromycin (EM; 92.0%), while EM resistance was only found in 2 out of the 42 human strains examined (4.8%). All EM-resistant swine strains (n=15) exhibited a common point mutation in the 23S rRNA sequence (A2085G), and the tetO gene was detected in 22 out of the 23 TET-resistant swine strains. A whole genome sequencing analysis of four representative swine ST-1562 strains revealed abundant AMR-associated gene clusters in their genomes, suggesting horizontal gene transfer events during host adaptation. This is the first study to demonstrate the phylogenetic diversity and AMR profiles of C. coli in Japan. The present results suggest that poultry and cattle are major reservoirs, improving our knowledge on the epidemiological and ecological traits of this pathogen.

Dietary Fructose and Microbiota-Derived Short-Chain Fatty Acids Promote Bacteriophage Production in the Gut Symbiont Lactobacillus reuteri

The mammalian intestinal tract contains a complex microbial ecosystem with many lysogens, which are bacteria containing dormant phages (prophages) inserted within their genomes. Approximately half of intestinal viruses are derived from lysogens, suggesting that these bacteria encounter triggers that promote phage production. We show that prophages of the gut symbiont Lactobacillus reuteri are activated during gastrointestinal transit and that phage production is further increased in response to a fructose-enriched diet. Fructose and exposure to short-chain fatty acids activate the Ack pathway, involved in generating acetic acid, which in turn triggers the bacterial stress response that promotes phage production. L. reuteri mutants of the Ack pathway or RecA, a stress response component, exhibit decreased phage production. Thus, prophages in a gut symbiont can be induced by diet and metabolites affected by diet, which provides a potential mechanistic explanation for the effects of diet on the intestinal phage community.

Phenotypic and Genotypic Examination of Antimicrobial Resistance in Thermophilic Campylobacter Species Isolated from Poultry in Turkey

Introduction

The study aimed to isolate thermophilic Campylobacter from chickens raised three rearing methods, determine its antimicrobial susceptibilities, and examine resistance-related genes by PCR.

Material and Methods

Cloacal swabs or intestinal contents were taken in Istanbul, Sakarya, and Izmir provinces. Chickens were from small village-based family-run businesses (n = 70), organically raised (n = 71), and conventionally raised broilers (n = 79). The samples were cultured on modified charcoal cefoperazone desoxycholate (mCCD) agar. Suspect isolates were identified with multiplex PCR (mPCR). As per EUCAST standards, MIC values were derived by broth microdilution for tetracycline, ciprofloxacin, nalidixic acid, kanamycin, gentamicin, and erythromycin in isolates of C. jejuni (n = 98) and C. coli (n = 83).

Results

In C. jejuni, 78.6% tetracycline, 87.8% ciprofloxacin, and 81.6% nalidixic acid resistance was detected, but none was to kanamycin, gentamicin, or erythromycin. In C. coli, 98.8% ciprofloxacin and 63.9% nalidixic acid resistance was detected, whereas resistance to non-quinolones was not observed. C257T (Thr-86-Ile) mutation in the gyrA gene of all phenotypically quinolone-resistant isolates was detected through a mismatch amplification mutation assay PCR (MAMA-PCR). It emerged that all isolates bore the tet (O) resistance gene.

Conclusion

Common tetracycline, nalidixic acid, and ciprofloxacin resistance exists in Campylobacter isolated from chickens raised three rearing methods.

Molecular Identification of Multidrug-Resistant Campylobacter Species From Diarrheal Patients and Poultry Meat in Shanghai, China

Emerging resistance to the antimicrobial agents of choice for treatment of thermophilic Campylobacter infections is becoming a serious threat to public health. In this study, 548 Campylobacter (372 C. jejuni and 176 C. coli) isolates from diarrheal patients and poultry meat were subjected for antibiotic susceptibility analysis to ciprofloxacin, tetracycline, gentamicin, erythromycin and clindamycin. Among them, 151 Campylobacter (32 C. jejuni and 119 C. coli) were identified as multidrug resistant isolates. PFGE analysis was performed on the 151 multidrug resistant isolates to determine their genetic relatedness, and 103 PFGE genotypes were determined. Some isolates from both human and chicken belonged to identical genotypes, indicating these clones might be able to spread between human and chicken. Antibiotic resistant genes of the 151 isolates were identified. The numbers of isolates carried tet (O), aadE, ermB, and aadE-sat4-aphA were 148 (98%), 89 (58.9%), 31 (20.5%), and 10 (6.6%), respectively. Almost all (n = 150, 99.3%) had gyrA mutation at codon 86. And the 23s rRNA A2075G point mutation was found in 56 (37.1%) isolates. Gene mutations at the cmeR-cmeABC intergenic region may lead to the activation of CmeABC multidrug efflux pump, and in this study novel sequence types of the intergenic region were identified in both C. jejuni and C. coli. This study determined the genetic prerequisites for antibiotic resistance of multidrug resistant Campylobacter isolates from diarrheal patients and poultry meat in Shanghai, China.

Genetic Basis and Clonal Population Structure of Antibiotic Resistance in Campylobacter jejuni Isolated From Broiler Carcasses in Belgium

Human campylobacteriosis is the leading food-borne zoonosis in industrialized countries. This study characterized the clonal population structure, antimicrobial resistance profiles and occurrence of antimicrobial resistance determinants of a set of Campylobacter jejuni strains isolated from broiler carcasses in Belgium. Minimum inhibitory concentrations (MICs) against five commonly-used antibiotics (ciprofloxacin, nalidixic acid, tetracycline, gentamicin, and erythromycin) were determined for 204 C. jejuni isolates. More than half of the isolates were resistant to ciprofloxacin or nalidixic acid. In contrast, a lower percentage of screened isolates were resistant to gentamicin or erythromycin. C. jejuni isolates resistant to ciprofloxacin and/or nalidixic acid were screened for the substitution T86I in the quinolone resistance determining region (QRDR) of the gyrA gene, while C. jejuni isolates resistant to tetracycline were screened for the presence of the tet(O) gene. These resistance determinants were observed in most but not all resistant isolates. Regarding resistance to erythromycin, different mutations occurred in diverse genetic loci, including mutations in the 23S rRNA gene, the rplD and rplV ribosomal genes, and the intergenic region between cmeR and cmeABC. Interestingly, and contrary to previous reports, the A2075G transition mutation in the 23S rRNA gene was only found in one strain displaying a high level of resistance to erythromycin. Ultimately, molecular typing by multilocus sequence typing revealed that two sequence types (ST-824 and ST-2274) were associated to quinolones resistance by the presence of mutations in the gene gyrA (p = 0.01). In addition, ST-2274 was linked to the CIP-NAL-TET-AMR multidrug resistant phenotype. In contrast, clonal complex CC-45 was linked to increased susceptibility to the tested antibiotics. The results obtained in this study provide better understanding of the phenotypic and the molecular basis of antibiotic resistance in C. jejuni, unraveling some the mechanisms which confer antimicrobial resistance and particular clones associated to the carriage and spread of resistance genes.

Development and evaluation of a PCR assay for rapid detection of azithromycin resistant Campylobacter isolated from diarrhoeal patients in Kolkata, India

Background

Campylobacter is a well-known bacterial pathogen for triggering acute gastroenteritis in humans both in developed and developing countries. This organism is highly resistant to fluoroquinolones. Macrolides are very much useful for the treatment of campylobacteriosis when clinical therapy is necessary. However, increasing resistance to azithromycin, a potent macrolide has been reported in Campylobacter in recent years. Macrolide resistance in Campylobacter is found mainly due to point mutation in V region of 23S rRNA.

Results

We have developed a PCR based assay, which can detect the azithromycin resistant and sensitive Campylobacter strains utilizing mutation responsible for the phenotype. This PCR was validated using 359 Campylobacter strains isolated from diarrhoeal patients at Kolkata, India. Antimicrobial resistance through disk diffusion method was also performed on these strains as a gold standard. Studies through sequencing analysis further confirmed the PCR result.

Conclusion

This study describes a simple and rapid method for detection of mutation conferring macrolide resistance with additional feature of identification of sensitive strains.

Antimicrobial Resistance of Campylobacter Species Isolated from Broilers in Live Bird Markets in Shanghai, China

This study was conducted to determine the prevalence of antimicrobial resistance in Campylobacter spp. isolates from broilers in live bird markets (LBMs). A total of 209 Campylobacter spp. isolates (84 Campylobacter jejuni; 125 Campylobacter coli) were recovered from 364 broiler cecum samples collected from five LBMs in Shanghai, China. Minimum inhibitory concentrations of 13 antimicrobials were determined using agar dilution method. More than 96% of the Campylobacter spp. isolates were resistant to quinolones and tetracyclines. A high prevalence of macrolide resistance (erythromycin, 84.0%; azithromycin, 80.8%) was observed in C. coli, but not in C. jejuni (erythromycin, 6.0%; azithromycin, 2.4%). C. coli also showed significantly higher resistance than C. jejuni to clindamycin, gentamicin, and kanamycin. In contrast, C. coli isolates had lower resistance to florfenicol than the C. jejuni isolates. The majority of the C. jejuni (88.1%) and C. coli (97.6%) isolates exhibited multidrug resistance (MDR) to three or more classes of antimicrobials. All of the 208 ciprofloxacin-resistant Campylobacter spp. isolates were positive for the C257T mutation of the gyrA gene. In addition, the tet(O) gene was identified in all of the 202 doxycycline-resistant Campylobacter spp. isolates. Furthermore, 75.7% and 20.4% of the 103 azithromycin-resistant Campylobacter spp. isolates were positive for the A2075G mutation of the 23S rRNA gene and the presence of the erm(B) gene, respectively. Moreover, the cat gene was found in 14.3% (8/56) and 76.8% (73/95) of the chloramphenicol-resistant C. jejuni and C. coli isolates, respectively. To the best of our knowledge, this is the first report of the prevalence of antimicrobial resistance among Campylobacter spp. isolates originating from LBMs. The high prevalence of MDR Campylobacter spp. isolates in LBMs highlights the need to implement efficient intervention measures to control not only Campylobacter contamination in LBMs but also dissemination of antimicrobial resistance among Campylobacter spp. in poultry production.

Antimicrobial resistance of Campylobacter isolates from small scale and backyard chicken in Kenya

BACKGROUND

Thermophilic Campylobacter species are a major cause of bacterial foodborne diarrhoea in humans worldwide. Poultry and their products are the predominant source for human campylobacteriosis. Resistance of Campylobacter to antibiotics is increasing worldwide, but little is known about the antibiotic resistance in Campylobacter isolated from chicken in Kenya. In this study, 35 suspected Campylobacter strains isolated from faeces and cloacal swabs of chicken were tested for their susceptibility to seven antibiotics using a broth microdilution assay and molecular biological investigations.

RESULTS

Overall, DNA of thermophilic Campylobacter was identified in 53 samples by PCR (34 C. jejuni, 18 C. coli and one mix of both species) but only 35 Campylobacter isolates (31 C. jejuni and 4 C. coli) could be re-cultivated after transportation to Germany. Isolates were tested for their susceptibility to antibiotics using a broth microdilution assay. Additionally, molecular biological detection of antibiotic resistance genes was carried out. C. jejuni isolates showed a high rate of resistance to nalidixic acid, tetracycline and ciprofloxacin of 77.4, 71.0 and 71.0 %, respectively. Low resistance (25.8 %) was detected for gentamicin and chloramphenicol. Multidrug resistance in C. jejuni could be detected in 19 (61.3 %) isolates. Resistance pattern of C. coli isolates was comparable. Resistance to ciprofloxacin was confirmed by MAMA-PCR and PCR-RFLP in all phenotypically resistant isolates. The tet(O) gene was detected only in 54.5 % of tetracycline resistant C. jejuni isolates. The tet(A) gene, which is also responsible for tetracycline resistance, was found in 90.3 % of C. jejuni and in all C. coli isolates. Thirteen phenotypically erythromycin-resistant isolates could not be characterised by using PCR-RFLP and MAMA-PCR.

CONCLUSIONS

To the best of our knowledge, this study is the first report about resistance to antibiotics in thermophilic Campylobacter originating from chicken in Kenya. Campylobacter spp. show a high level of resistance to ciprofloxacin, nalidixic acid and tetracycline but also a remarkable one to chloramphenicol and gentamicin and they are multidrug resistant. Resistance to antibiotics is a global public health concern. In Kenya, resistance surveillance needs further attention in the future. Efforts to establish at least a National Laboratory with facilities for performing phenotypic and genotypic characterization of thermophilic Campylobacter is highly recommended.

Genotyping of vitamin D receptor gene polymorphisms using mismatched amplification mutation assay in neonatal sepsis patients of Odisha, eastern India

Vitamin D has potent antimicrobial and anti-inflammatory properties. Vitamin D deficiency has been shown to be associated with the risk of vulnerability to different infectious diseases, such as neonatal sepsis. Polymorphisms in vitamin D receptor (VDR) gene can influence the expression of vitamin D in individuals. Hence, it is essential to study the vitamin D status and VDR gene polymorphisms for assessing neonatal sepsis risk. In this study, we assessed the serum 25(OH)D, the main circulating form of vitamin D and VDR polymorphism on 120 subjects in a case-control approach, recruiting 60 subjects in each category. We genotyped Fok1, Bsm1, Apa1 and Taq1 gene polymorphisms in VDR by developing a unique mismatch amplification mutation assay (MAMA) and studied their association in both populations. VDR-MAMA primers were designed by addition of dual mismatches (DM) near the 3' end and were selected based on high ΔCt values in comparison to single mismatch (SM) primers using SYBR-Green RT-PCR, which were eventually used for VDR genotyping. Genotyping was also performed using PCR-RFLP for further confirmation. Serum 25(OH)D ELISA revealed that cases were vitamin D insufficient (Median=12.16ng/ml, 95% CI: 3.84-22.22) and controls were vitamin D sufficient (Median=30.22ng/ml, 95% CI: 20.08-46.78; p<0.0001) respectively, which indicated that vitamin D insufficiency was mostly prevalent in cases. We found no evidence of association between genotypes of the Apa1 polymorphism and neonatal sepsis or 25(OH)D serum levels. The distributions of the Fok1, Bsm1, and Taq1 genotypes were not consistent with Hardy-Weinberg equilibrium in the control group. Future studies in larger populations are required to establish whether the VDR polymorphisms can be potentially used as genetic markers for early screening towards predisposition to neonatal sepsis risk. In this study, we describe a simple, inexpensive and rapid screening of VDR gene polymorphisms using VDR MAMA-PCR, which can be used in both clinical and research laboratories.

Genotyping and antibiotic resistance of thermophilic Campylobacter isolated from chicken and pig meat in Vietnam

BACKGROUND

Campylobacter species are recognized as the most common cause of foodborne bacterial gastroenteritis in humans. In this study nine Campylobacter strains isolated from chicken meat and pork in Hanoi, Vietnam, were characterized using molecular methods and tested for antibiotic resistance.

RESULTS

The nine isolates (eight C. jejuni and one C. coli) were identified by multiplex PCR, and tested for the presence or absence of 29 gene loci associated with virulence, lipooligosaccharide (LOS) biosynthesis and further functions. flaA typing, multilocus sequence typing and microarray assay investigation showed a high degree of genetic diversity among these isolates. In all isolates motility genes (flaA, flaB, flhA, fliM), colonization associated genes (cadF, docB), toxin production genes (cdtA, cdtB, secD, secF), and the LOS biosynthesis gene pglB were detected. Eight gene loci (fliY, virB11, Cje1278, Cj1434c, Cj1138, Cj1438c, Cj1440c, Cj1136) could not be detected by PCR. A differing presence of the gene loci ciaB (22.2 %), Cje1280 (77.8 %), docC (66.7 %), and cgtB (55.6 %) was found. iamA, cdtC, and the type 6 secretion system were present in all C. jejuni isolates but not in C. coli. flaA typing resulted in five different genotypes within C. jejuni, MLST classified the isolates into seven sequence types (ST-5155, ST-6736, ST-2837, ST-4395, ST-5799, ST-4099 and ST-860). The microarray assay analysis showed a high genetic diversity within Vietnamese Campylobacter isolates which resulted in eight different types for C. jejuni. Antibiotic susceptibility profiles showed that all isolates were sensitive to gentamicin and most isolates (88.8 %) were sensitive to chloramphenicol, erythromycin and streptomycin. Resistance rates to nalidixic acid, tetracycline and ciprofloxacin were 88.9, 77.8 and 66.7 %, respectively.

CONCLUSIONS

To the best of our knowledge, this study is the first report that shows high genetic diversity and remarkable antibiotic resistance of Campylobacter strains isolated from meat in Vietnam which can be considered of high public health significance. These preliminary data show that large scale screenings are justified to assess the relevance of Campylobacter infections on human health in Vietnam.

Molecular subtyping and erythromycin resistance of Campylobacter in China

AIMS

To investigate the erythromycin resistance patterns and mechanism for Campylobacter isolates in China.

METHODS AND RESULTS

The minimum inhibitory concentrations of erythromycin on 858 Chinese Campylobacter isolates were analysed. PCR and DNA sequencing were used to identify mutations in the 23S rRNA and the presence of the ermB gene in the 158 erythromycin resistance isolates (18·4%). About 83% (131/158) had A2075G mutation in their 23S rRNA; no A2074C/G mutants were found. The ermB gene was identified in 30 Campylobacter coli isolates (19%). Four types of multidrug-resistant gene islands (MDRGIs) were found. Fifty-three types were identified by multilocus sequence typing among the resistant isolates. All isolates of STs 6322 and 1145 had the ermB gene.

CONCLUSIONS

The erythromycin resistance rate of Camp. coli (58·56%) was much higher than Campylobacter jejuni (0·67%). The insertion sites between cadF and CCO1582 and between nfsB and cinA on the chromosome might be hot spots for MDRGI transformation.

SIGNIFICANCE AND IMPACT OF THE STUDY

Point mutation in domain V of the 23S rRNA and the ermB gene accounted for 100% of the erythromycin resistance of Campylobacter in China.

Identification of Campylobacter jejuni and determination of point mutations associated with macrolide resistance using a multiplex TaqMan MGB real-time PCR

AIMS

The aim of the study was to develop a multiplex real-time PCR method to identify Campylobacter jejuni containing mutations commonly associated with macrolide resistance.

METHODS AND RESULTS

A multiplex fluorescence real-time PCR assay was developed based on TaqMan minor groove binder (MGB) probes. The VS1-MGB probe was designed based on the VS1 gene and was used to identify Camp. jejuni. The 23S rDNA-MGB probe was designed to distinguish macrolide resistance mutations in 23S rDNA, while 57D-MGB and 74D-MGB were designed to detect resistance mutations in ribosomal protein L4. The specificity and accuracy of our method were identical to the conventional biochemical tests, mapA PCR, minimum inhibitory concentration (MIC) determination and DNA sequencing. The linear detection limit of the method was 0·03 ng genomic DNA and three colony formation unit (CFU) per reaction. In 6 of 18 cases, the nature of Erythromycin resistance could be correctly determined from natural isolates; absence of the tested mutations was demonstrated in the remaining four resistant isolates.

CONCLUSIONS

A multiplex TaqMan MGB real-time PCR assay with high specificity and accuracy was developed to simultaneously identify Camp. jejuni and detect the gene mutations associated with macrolide resistance.

SIGNIFICANCE AND IMPACT OF THE STUDY

This multiplex method can potentially simplify the identification of Camp. jejuni and determine macrolide resistance due to mutations in 23S rDNA or ribosomal protein L4. This method has a potential for application in different research areas and molecular surveillance.

Emergence of multidrug-resistant Campylobacter species isolates with a horizontally acquired rRNA methylase

Antibiotic-resistant Campylobacter constitutes a serious threat to public health, and resistance to macrolides is of particular concern, as this class of antibiotics is the drug of choice for clinical therapy of campylobacteriosis. Very recently, a horizontally transferrable macrolide resistance mediated by the rRNA methylase gene erm(B) was reported in a Campylobacter coli isolate, but little is known about the dissemination of erm(B) among Campylobacter isolates and the association of erm(B)-carrying isolates with clinical disease. To address this question and facilitate the control of antibiotic-resistant Campylobacter, we determined the distribution of erm(B) in 1,554 C. coli and Campylobacter jejuni isolates derived from food-producing animals and clinically confirmed human diarrheal cases. The results revealed that 58 of the examined isolates harbored erm(B) and exhibited high-level resistance to macrolides, and most were recent isolates, derived in 2011-2012. In addition, the erm(B)-positive isolates were all resistant to fluoroquinolones, another clinically important antibiotic used for treating campylobacteriosis. The erm(B) gene is found to be associated with chromosomal multidrug resistance genomic islands (MDRGIs) of Gram-positive origin or with plasmids of various sizes. All MDRGIs were transferrable to macrolide-susceptible C. jejuni by natural transformation under laboratory conditions. Molecular typing of the erm(B)-carrying isolates by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) identified diverse genotypes and outbreak-associated diarrheal isolates. Molecular typing also suggested zoonotic transmission of erm(B)-positive Campylobacter. These findings reveal an emerging and alarming trend of dissemination of erm(B) and MDRGIs in Campylobacter and underscore the need for heightened efforts to control their further spread.

Prevalence and antimicrobial resistance of Campylobacter spp. isolated from poultry carcasses in Poland

The purpose of the present study was to determine the prevalence of Campylobacter in poultry carcasses at slaughter in Poland. For the isolated strains, resistance to selected antibiotics and the associated genetic determinants were identified. A total of 498 Campylobacter isolates were obtained from 802 poultry samples during the 2-year study period. Strains were identified to species with the PCR method; 53.6% of the strains were Campylobacter jejuni and 46.4% were Campylobacter coli. A high percentage of the tested Campylobacter strains were resistant to ciprofloxacin and nalidixic acid (74.1 and 73.5%, respectively) followed by tetracycline (47.4%) and streptomycin (20.5%). Only one C. jejuni and two C. coli isolates were resistant to gentamicin. Seventy-nine (15.9%) of the 498 strains were resistant to three or more classes of antibiotics examined. Higher levels of resistance, irrespective of the antimicrobial agent tested, were found within the C. coli group. Almost all strains resistant to quinolones (99.5%) and to tetracycline (99.6%) carried the Thr-86-to-Ile mutation in the gyrA gene and possessed the tet(O) marker, respectively. All isolates resistant to erythromycin had the A2075G mutation in the 23S rRNA gene. These results reveal that poultry carcasses in Poland are a reservoir of potentially pathogenic and antimicrobial-resistant Campylobacter strains for humans, which may pose a public health risk.

Antimicrobial resistance in campylobacter: susceptibility testing methods and resistance trends

Most Campylobacter infections are self-limiting but antimicrobial treatment (e.g., macrolides, fluoroquinolones) is necessary in severe or prolonged cases. Susceptibility testing continues to play a critical role in guiding therapy and epidemiological monitoring of resistance. The methods of choice for Campylobacter recommended by the Clinical and Laboratory Standards Institute (CLSI) are agar dilution and broth microdilution, while a disk diffusion method was recently standardized by the European Committee on Antimicrobial Susceptibility Testing (EUCAST). Macrolides, quinolones, and tetracyclines are among the common antimicrobials recommended for testing. Molecular determination of Campylobacter resistance via DNA sequencing or PCR-based methods has been performed. High levels of resistance to tetracycline and ciprofloxacin are frequently reported by many national surveillance programs, but resistance to erythromycin and gentamicin in Campylobacter jejuni remains low. Nonetheless, variations in susceptibility observed over time underscore the need for continued public health monitoring of Campylobacter resistance from humans, animals, and food.

Determination of antimicrobial sensitivities of Campylobacter jejuni isolated from commercial turkey farms in Germany

The emergence of antimicrobial resistance among Campylobacter isolates recovered from turkeys has increased dramatically. Monitoring the progress of this resistance becomes a growing public health issue. The aim of the present study was to provide information of the current status of antibiotic resistance patterns in Campylobacter jejuni from turkeys. Seventy-six C. jejuni isolates were recovered from 67 epidemiologically unrelated meat turkey flocks in different regions of Germany in 2010 and 2011. The isolates were typed by flaA genotyping and were investigated for antimicrobial susceptibility against 12 antibiotics by using a broth microdilution test as well as testing the genetic determination of ciprofloxacin, tetracycline, and erythromycin resistance. All isolates (n = 76) were sensitive to gentamicin and chloramphenicol. The numbers of isolates that were sensitive to streptomycin, erythromycin, neomycin, and amoxicillin were 69 (90.8%), 61 (80.2%), 58 (76.4%), and 44 (57.9%), respectively. Only one isolate was sensitive to all tested antibiotics. The emergence of a high resistance rate and multidrug resistance to three or more classes of antimicrobial agents were observed. The resistance against sulphamethoxazole/trimethoprim, metronidazole, ciprofloxacin, naladixic acid, and tetracycline was 58 (76.3%), 58 (76.3%), 53 (69.7%), 51 (67.1%), and 42 (55.3%), respectively. None of the isolates was resistant to all antibiotics. Multidrug resistance to three or more classes of antimicrobial agents was found and ranged from 3.9% to 40.8%. Replacement of the Thr-86-->Ile in gyrA gene and detection of the tet(O) gene were the main resistance mechanisms for fluoroquinolones and tetracycline, respectively, while the lack of mutation in position 2074 and 2075 on the 23S rRNA gene was responsible for macrolide resistance. The phenotypic and genotypic resistance profiles were compatible in the case of ciprofloxacin and tetracycline but were not completely congruent with respect to erythromycin.

Interleukin-28B genotyping by melt-mismatch amplification mutation assay PCR analysis using single nucleotide polymorphisms rs12979860 and rs8099917, a useful tool for prediction of therapy response in hepatitis C patients

Several studies have identified associations between single nucleotide polymorphisms (SNPs) occurring near the interleukin-28B (IL-28B) gene and response to antiviral treatment among hepatitis C virus (HCV) patients. Here, we describe a reliable melt-mismatch amplification mutation assay (melt-MAMA) PCR-based genotyping method for IL-28B which can be used in the management of HCV patients, helping to better define the course of therapy.

Antimicrobial resistance in Campylobacter coli isolated from pigs in two provinces of China

The aim of this study was to determine the prevalence, antimicrobial resistance and molecular epidemiology of Campylobacter coli isolated from swine in China. A total of 190 C. coli isolates obtained from two slaughter houses and ten conventional pig farms in Shandong (SD, n=95) and Ningxia (NX, n=95) provinces were tested for their susceptibility to 14 antimicrobials. A high prevalence (>95%) of ciprofloxacin and tetracycline-resistant strains was observed in both SD and NX. The erythromycin and clindamycin resistance rates of C. coli from NX (ERY: 54.7% CLI: 43.2%) were higher than those from SD (ERY: 37.9%, CLI: 35.8%). A significant difference (P<0.05) was observed in erythromycin resistance rate, but not (P>0.05) in clindamycin resistance rate. while the resistance rates of ampicillin and kanamycin in NX (AMP: 34.7%, KAN: 43.2%) were significantly lower (P<0.05) than those in SD (AMP: 51.6%, KAN: 71.6%). None of the tested isolates were resistant to phenicols. The majority of the isolates from both provinces (SD: 80% and NX: 73.7%) showed multi-drug resistance profiles. The point mutations of A2075G in the 23S rRNA and C257T in the gyrA gene were detected in 98% (87/89) of macrolide resistant isolates and all ciprofloxacin resistant isolates, respectively. In addition, all tetracycline-resistant isolates harbored the tet(O) gene. The high prevalence of antimicrobial resistance in C. coli strains derived from pigs in China was observed and was likely due to the extensive use of various antimicrobials. Prudent use of antimicrobial agents on farms should be further emphasized to control the dissemination of antimicrobial resistant C. coli.

23S rRNA gene mutations contributing to macrolide resistance in Campylobacter jejuni and Campylobacter coli

The genetic basis of macrolide resistance in Campylobacter coli (n = 17) and C. jejuni (n = 35) isolates previously subjected to in vivo selective pressure was investigated to determine if the number of copies of 23S rRNA genes with macrolide-associated mutations affects the minimum inhibitory concentration (MIC) of macrolides. Sequence data for domain V of the 23S rRNA gene revealed that two macrolide-resistant C. coli isolates had adenine-->guanine transitions at position 2059 (A2059G, Escherichia coli numbering). One of the two isolates had the A2059G transition in only two of the three gene copies. Among the macrolide-resistant C. jejuni isolates (n = 9), two different point mutations within domain V were observed. Three macrolide-resistant C. jejuni isolates had A2059G transitions. One of these three C. jejuni isolates had the A2059G transition in only two of the three gene copies. Six macrolide-resistant C. jejuni isolates had an adenine-->cytosine transversion at position 2058 (A2058C, E. coli numbering) in all three copies of the 23S rRNA gene. Campylobacter jejuni isolates with the A2058C transversion had higher erythromycin MICs (>256 microg/mL) compared to C. jejuni isolates with A2059G transitions (64-128 microg/mL). In addition, the C. jejuni and C. coli isolates with only two copies of the 23S rRNA gene having A2059G substitutions had lower macrolide MICs compared to isolates with all three copies of the gene mutated. No isolates were observed having only one copy of the 23S rRNA gene with a mutation. Sequence analysis of ribosomal proteins L4 (rplD) and L22 (rplV) indicated that ribosomal protein modifications did not contribute to macrolide resistance among the collection of Campylobacter examined.

Detection of resistance to macrolides in thermotolerant campylobacter species by fluorescence in situ hybridization

The resistance of enteritis-causing Campylobacter strains to erythromycin is an emerging problem. We therefore evaluated fluorescence in situ hybridization (FISH) for the rapid detection of resistance using 74 campylobacter isolates. FISH showed specificity and sensitivity of 100% for the detection of high-level resistance.