Genetic characterization and antimicrobial susceptibility of Campylobacter spp. isolated from domestic and imported chicken meats and humans in Korea

Antimicrobial Susceptibility Patterns and Genetic Diversity of Campylobacter spp. Isolates from Patients with Diarrhea in South Korea

This study aimed to characterize the latest antimicrobial resistance patterns and genetic diversity of Campylobacter spp. isolated from patients with acute diarrhea in Korea. In total, 371 clinical isolates (361 Campylobacter jejuni and 10 Campylobacter coli) were collected from patients with diarrhea in 106 medical institutions of six provinces during the seasonal peak (April-September 2022) in South Korea. We then assessed their antimicrobial susceptibility to eight antimicrobial agents and performed multilocus sequence typing (MLST). This study investigated the antimicrobial resistance (AMR) profiles to tetracycline (32.3%), nalidixic acid (64.9%), and ciprofloxacin (83.3%), confirming high levels of the latter even after its Korean ban in 2010. However, tetracycline resistance displayed a decreasing trend. Alternatively, significantly lower resistance rates to clindamycin (0.8%), azithromycin (0.53%), erythromycin (0.53%), and gentamicin (0.53%) as well as absolute susceptibility to florfenicol (0%) were observed. Four C. jejuni and three C. coli isolates (7/371, 1.88%) were classified as multidrug-resistant (MDR) to at least three antimicrobial classes. MLST identified a high genetic diversity with 21 clonal complexes (CCs) and sixty-six sequence types (STs), including eight novel STs. The high CC frequency of C. jejuni comprised CC21 (37.7%), CC22 (13.8%), and CC206 (9.4%), while C. coli was predominated by CC828 (90%). The high CC21 and CC828 strain prevalence in this study was consistent with their worldwide distribution. This study highlights that quinolone- and tetracycline-resistant Campylobacter circulate in Korea with diverse genotypes, providing important information that could contribute to controlling and preventing increasing antimicrobial resistance in patients.

Antimicrobial Usage, Susceptibility Profiles, and Resistance Genes in Campylobacter Isolated from Cattle, Chicken, and Water Samples in Kajiado County, Kenya

Campylobacter organisms are the major cause of bacterial gastroenteritis and diarrhoeal illness in man and livestock. Campylobacter is growingly becoming resistant to critically crucial antibiotics; thereby presenting public health challenge. This study aimed at establishing antimicrobial use, susceptibility profiles, and resistance genes in Campylobacter isolates recovered from chicken, cattle, and cattle-trough water samples. The study was conducted between October 2020 and May 2022 and involved the revival of cryopreserved Campylobacter isolates confirmed by PCR from a previous prevalence study in Kajiado County, Kenya. Data on antimicrobial use and animal health-seeking behaviour among livestock owners (from the same farms where sampling was done for the prevalence study) were collected through interview using a pretested semistructured questionnaire. One hundred and three isolates (29 C. coli (16 cattle isolates, 9 chicken isolates, and 4 water isolates) and 74 C. jejuni (38 cattle isolates, 30 chicken isolates, and 6 water isolates)) were assayed for phenotypic antibiotic susceptibility profile using the Kirby-Bauer disk diffusion method for ampicillin (AX), tetracycline (TE), gentamicin (GEN), erythromycin (E), ciprofloxacin (CIP), and nalidixic acid (NA). Furthermore, detection of genes conferring resistance to tetracyclines (tet (O), β-lactams (bla _OXA-61), aminoglycosides (aph-3-1), (fluoro)quinolones (gyrA), and multidrug efflux pump (cmeB) encoding resistance to multiple antibiotics was detected by mPCR and confirmed by DNA sequencing. The correlation between antibiotic use and resistance phenotypes was determined using the Pearson's correlation coefficient (r) method. Tetracyclines, aminoglycosides, and β-lactam-based antibiotics were the most commonly used antimicrobials; with most farms generally reported using antimicrobials in chicken production systems than in cattle. The highest resistance amongst isolates was recorded in ampicillin (100%), followed by tetracycline (97.1%), erythromycin (75.7%), and ciprofloxacin (63.1%). Multidrug resistance (MDR) profile was observed in 99 of 103 (96.1%) isolates; with all the Campylobacter coli isolates displaying MDR. All chicken isolates (39/39, 100%) exhibited multidrug resistance. The AX-TE-E-CIP was the most common MDR pattern at 29.1%. The antibiotic resistance genes were detected as follows: tet (O), gyrA, cmeB, bla _OXA-61 , and aph-3-1 genes were detected at 93.2%, 61.2%, 54.4%, 36.9%, and 22.3% of all Campylobacter isolates, respectively. The highest correlations were found between tet (O) and tetracycline-resistant phenotypes for C. coli (96.4%) and C. jejuni (95.8%). A moderate level of concordance was observed between the Kirby-Bauer disk diffusion method (phenotypic assay) and PCR (genotypic assay) for tetracycline in both C. coli (kappa coefficient = 0.65) and C. jejuni (kappa coefficient = 0.55). The study discloses relatively high resistance profiles and multidrug resistance to antibiotics of critical importance in humans. The evolution of the multidrug-resistantCampylobacter isolates has been linked to the use and misuse of antimicrobials. This poses a potential hazard to public and animal health, necessitating need to reduce the use of antibiotics in livestock husbandry practice coupled with stringent biosecurity measures to mitigate antimicrobial resistance.

Campylobacter spp. isolated from poultry in Iran: Antibiotic resistance profiles, virulence genes, and molecular mechanisms

Campylobacter spp. genera is one of the most common causes of microbial enteritis worldwide. The objective of this work was to investigate the antimicrobial resistance (AMR) patterns, virulence genes, and genetic variation of thermophilic Campylobacter species collected from chicken meat samples in Iran. A total of 255 meat specimens were taken and transferred to the laboratory. Culture methods were utilized to identify the Campylobacter genus, and PCR and sequencing were performed to confirm the organisms. Antimicrobial susceptibility evaluation was performed using broth microdilution for six antimicrobials [ciprofloxacin (CIP), nalidixic acid (NAL), sitafloxacin (SIT), erythromycin (ERY), tetracycline (TET), and gentamicin (GEN)]. By using PCR, AMR and virulence genes were detected. The detection rate of Campylobacter spp. was 64 (25.09%) out of 255 meat samples, with C. jejuni and C. coli accounting for 41 (64.06%) and 14 (21.87%), respectively. Other Campylobacter isolates accounted for 14.06% of the total (nine samples). The antibiotic susceptibility of all Campylobacter isolates was tested using six antibiotics, and all (100%) were resistant to CIP and NAL. However, TET resistance was observed in 93.9% and 83.3% of C. jejuni and C. coli isolates, respectively. Four (8.2%) C. jejuni isolates were multidrug-resistant (MDR), while none of the C. coli isolates were MDR. Two of the four MDR isolates were resistant to CIP, NAL, TET, and ERY, whereas the other two isolates were resistant to CIP, NAL, TET, and GEN. The values of the Minimum Inhibitory Concentration (MIC) were as follows: CIP, 64-256 μg/ml; NAL, 128-512 μg/ml; TET, 2-1024 μg/ml; SIT, 0.25-1 μg/ml; ERY, 1-32 μg/ml; and GEN, 1-256 μg/ml. recR, dnaJ, cdtC, cdtB, cdtA, flaA, ciaB, cadF, and pidA were discovered in more than 50% of C. jejuni isolates, although wlaN, virbll, cgtB, and ceuE were found in <50%. flaA, cadF, pidA, and ciaB were discovered in more than 50% of the C. coli samples, whereas recR, cdtC, cdtB, cdtA, and cgtB were found in less than half. For C. coli, the percentages for wlaN, dnaJ, virbll, and ceuE were all zero. The results of this study show Campylobacter isolates obtained from poultry have higher resistance to quinolones and TET, pathogenicity potential, and varied genotypes.

Comparative analysis of antimicrobial resistance and genetic characteristics of Escherichia coli from broiler breeder farms in Korea

Broiler breeder farms could be a reservoir of Escherichia coli, disseminating antimicrobial resistance and virulence factors. We investigated the antimicrobial resistance of E. coli from nine broiler breeder farms and characterised their resistance and virulence genes. A total of 256 E. coli showed a high level of resistance to tetracycline, nalidixic acid, ampicillin, and cephalothin, followed by trimethoprim-sulfamethoxazole and chloramphenicol. The resistance to nalidixic acid, ampicillin, trimethoprim–sulfamethoxazole, and chloramphenicol showed significant differences among the farms. Among 202 β-lactam-resistant E. coli, 138 carried β-lactamase genes. The most prevalent β-lactamase gene was blaTEM-1, of which the presence differed significantly across the farms. Out of 197 tetracycline-resistant E. coli isolates, tetA and tetB were detected in 164 and 50, with significant differences among the farms. Also, 45 of 196 nalidixic acid-resistant E. coli carried qnrS while 67 of 149 trimethoprim–sulfamethoxazole-resistant E. coli carried sul2. Among the five virulence genes tested, ompT was the most prevalent, and all genes except for iutA distributed significantly different among the farms. The phenotypic and genotypic characteristics of E. coli were significantly different among the farms; therefore, management at the breeder level is required to control the vertical transmission of E. coli.

Antimicrobial Resistance Profiles, Virulence Genes, and Genetic Diversity of Thermophilic Campylobacter Species Isolated From a Layer Poultry Farm in Korea

Thermophilic Campylobacter species are among the major etiologies of bacterial enteritis globally. This study aimed at assessing the antimicrobial resistance (AMR) profiles, virulence genes, and genetic diversity of thermophilic Campylobacter species isolated from a layer poultry farm in South Korea. One hundred fifty-three chicken feces were collected from two layer poultry farms in Gangneung, South Korea. The Campylobacter species were isolated by cultural techniques, while PCR and sequencing were used for species confirmation. Antimicrobial susceptibility testing for six antimicrobials [ciprofloxacin (CIP), nalidixic acid (NAL), sitafloxacin (SIT), erythromycin (ERY), tetracycline (TET), and gentamicin (GEN)] was carried out by broth microdilution. Three AMR and nine virulence genes were screened by PCR. Genotyping was performed by flaA-restriction fragment length polymorphism (RFLP) and multilocus sequence typing (MLST). Of the 153 samples, Campylobacter spp. were detected in 55 (35.9%), with Campylobacter jejuni and Campylobacter coli being 49 (89.1%) and six (10.9%), respectively. High-level resistance was observed for CIP (100%), NAL (100%), and TET (C. jejuni, 93.9%; C. coli: 83.3%). No resistance was observed for SIT. The missense mutation (C257T) in gyrA gene was confirmed by sequencing, while the tet(O) gene was similar to known sequences in GenBank. The rate of multidrug-resistant (MDR) strains was 8.2%, and they all belonged to C. jejuni. All Campylobacter isolates possessed five virulence genes (cdtB, cstII, flaA, cadF, and dnaJ), but none possessed ggt, while the rates for other genes (csrA, ciaB, and pldA) ranged between 33.3 and 95.9%. The flaA-RFLP yielded 26 flaA types (C. jejuni: 21 and C. coli: five), while the MLST showed 10 sequence types (STs) for C. jejuni and three STs for C. coli, with CC-607 (STs 3611) and CC-460 (ST-460) being predominant. Among the 10 STs of C. jejuni, three were newly assigned. The findings of this study highlight the increased resistance to quinolones and TET, the virulence potential, and the diverse genotypes among Campylobacter strains isolated from the layer poultry farm.

Susceptibility of Campylobacter Strains to Selected Natural Products and Frontline Antibiotics

Campylobacter species have developed resistance to existing antibiotics. The development of alternative therapies is, therefore, a necessity. This study evaluates the susceptibility of Campylobacter strains to selected natural products (NPs) and frontline antibiotics. Two C. jejuni strains (ATCC^® 33560^TM and MT947450) and two C. coli strains (ATCC^® 33559^TM and MT947451) were used. The antimicrobial potential of the NPs, including plant extracts, essential oils, and pure phytochemicals, was evaluated by broth microdilution. The growth was measured by spectrophotometry and iodonitrotetrazolium chloride. Antibiotic resistance genes (tet(O) and gyrA) were characterized at the molecular level. The minimum inhibitory concentrations (MICs) and the minimum bactericidal concentrations (MBCs) ranged from 25 to 1600 µg/mL. Cinnamon oil, (E)-Cinnamaldehyde, clove oil, eugenol, and baicalein had the lowest MIC and MBC values (25-100 µg/mL). MT947450 and MT947451 were sensitive to erythromycin and gentamicin but resistant to quinolones and tetracycline. Mutations in gyrA and tet(O) genes from resistant strains were confirmed by sequencing. The findings show that NPs are effective against drug-sensitive and drug-resistant Campylobacter strains. The resistance to antibiotics was confirmed at phenotypic and genotypic levels. This merits further studies to decipher the action mechanisms and synergistic activities of NPs.

Bonelli R, A. Penna B, P. Albuquerque J, M. Souza R, M. F. Cerqueira A. Antimicrobial Resistance in Farm Animals in Brazil: An Update Overview

In animal husbandry, antimicrobial agents have been administered as supplements to increase production over the last 60 years. Large-scale animal production has increased the importance of antibiotic management because it may favor the evolution of antimicrobial resistance and select resistant strains. Brazil is a significant producer and exporter of animal-derived food. Although Brazil is still preparing a national surveillance plan, several changes in legislation and timely programs have been implemented. Thus, Brazilian data on antimicrobial resistance in bacteria associated with animals come from official programs and the scientific community. This review aims to update and discuss the available Brazilian data on this topic, emphasizing legal aspects, incidence, and genetics of the resistance reported by studies published since 2009, focusing on farm animals and derived foods with the most global public health impact. Studies are related to poultry, cattle, and pigs, and mainly concentrate on non-typhoid Salmonella, Escherichia coli, and Staphylococcus aureus. We also describe legal aspects of antimicrobial use in this context; and the current occurrence of genetic elements associated with resistance to beta-lactams, colistin, and fluoroquinolones, among other antimicrobial agents. Data here presented may be useful to provide a better understanding of the Brazilian status on antimicrobial resistance related to farm animals and animal-derived food products.

Antimicrobial Resistance in Farm Animals in Brazil: An Update Overview

In animal husbandry, antimicrobial agents have been administered as supplements to increase production over the last 60 years. Large-scale animal production has increased the importance of antibiotic management because it may favor the evolution of antimicrobial resistance and select resistant strains. Brazil is a significant producer and exporter of animal-derived food. Although Brazil is still preparing a national surveillance plan, several changes in legislation and timely programs have been implemented. Thus, Brazilian data on antimicrobial resistance in bacteria associated with animals come from official programs and the scientific community. This review aims to update and discuss the available Brazilian data on this topic, emphasizing legal aspects, incidence, and genetics of the resistance reported by studies published since 2009, focusing on farm animals and derived foods with the most global public health impact. Studies are related to poultry, cattle, and pigs, and mainly concentrate on non-typhoid Salmonella, Escherichia coli, and Staphylococcus aureus. We also describe legal aspects of antimicrobial use in this context; and the current occurrence of genetic elements associated with resistance to beta-lactams, colistin, and fluoroquinolones, among other antimicrobial agents. Data here presented may be useful to provide a better understanding of the Brazilian status on antimicrobial resistance related to farm animals and animal-derived food products.

Hyper-Aerotolerant Campylobacter coli from Duck Sources and Its Potential Threat to Public Health: Virulence, Antimicrobial Resistance, and Genetic Relatedness

Campylobacter, a common foodborne human pathogen, is considered sensitive to oxygen. Recently, aerotolerant (AT) Campylobacter jejuni with the ability to survive under aerobic stress has been reported. Here, we investigated the prevalence of hyper-aerotolerant (HAT) Campylobacter coli from duck sources (118 carcasses and meat) and its characteristics to assess potential impacts on public health. Half of 56 C. coli isolates were HAT and most harbored various virulence genes including flaA, cadF, cdtA, ceuB, and wlaN. Moreover, 98.2% of C. coli isolates showed resistance to quinolones, including ciprofloxacin (CIP), and nine (16.1%) showed high-level resistance to ciprofloxacin (Minimum Inhibitory Concentration, MIC ≥ 32 μg/mL) and most of these were HAT. Based on genetic relatedness between C. coli from duck sources and those from human sources (PubMLST and NCBI), HAT isolates sharing the same MLST sequence types were significantly more prevalent than those not sharing the same sequence types as those from human sources. Therefore, HAT C. coli is prevalent in duck sources, and is most likely transmitted to humans through the food chain given its aerotolerance. This being so, it might pose a threat to public health given its virulence and antimicrobial resistance (AMR). This study will assist in improving control strategies to reduce farm-to-table HAT C. coli transmission to humans.

Comparative Analysis of Aerotolerance, Antibiotic Resistance, and Virulence Gene Prevalence in Campylobacter jejuni Isolates from Retail Raw Chicken and Duck Meat in South Korea

Human infections with Campylobacter are primarily associated with the consumption of contaminated poultry meat. In this study, we isolated Campylobacterjejuni from retail raw chicken and duck meat in Korea and compared their aerotolerance, antibiotic resistance, and virulence gene prevalence. Whereas C. jejuni isolates from chicken dominantly belonged to multilocus sequence typing (MLST) clonal complex (CC)-21, CC-45 is the common MLST sequence type in duck meat isolates. C. jejuni strains from both chicken and duck meat were highly tolerant to aerobic stress. The prevalence of virulence genes was higher in C. jejuni strains from chicken than those from duck meat. However, antibiotic resistance was higher in duck meat isolates than chicken isolates. Based on the prevalence of virulence genes and antibiotic resistance, fluoroquinolone-resistant C. jejuni strains harboring all tested virulence genes except virB11 were predominant on retail poultry. Fluoroquinolone-resistant C. jejuni strains carrying most virulence genes were more frequently isolated in summer than in winter. The comparative profiling analysis in this study successfully demonstrated that antibiotic-resistant and pathogenic strains of C. jejuni are highly prevalent on retail poultry and that retail duck meat is an important vehicle potentially transmitting C. jejuni to humans in Korea.

High-Level Ciprofloxacin-Resistant Campylobacter jejuni Isolates Circulating in Humans and Animals in Incheon, Republic of Korea

Campylobacter jejuni is one of the major causative pathogens of outbreaks or sporadic cases of diarrhoeal diseases worldwide. In this study, we compared the phenotypic and genetic characteristics of C. jejuni isolates of human and food-producing animal origins in Korea and examined the genetic relatedness between these two groups of isolates. Regardless of isolation source, all C. jejuni isolates harboured four virulence genes, cadF, cdtB, ciaB and racR, whereas the wlaN and virB11 genes were more frequently observed in human isolates. Antimicrobial susceptibility testing showed that the majority of C. jejuni isolates displayed high-level resistance to fluoroquinolone (95.2%) or tetracycline (76.2%) antibiotics, and 12.4% of isolates exhibited multidrug resistance (more than three classes of antibiotics tested). Pulsed-field gel electrophoresis (PFGE) of all Campylobacter isolates revealed 51 different SmaI-PFGE patterns and six major clusters containing both human and animal isolates. These results indicate that genetically diverse strains of C. jejuni with antimicrobial drug-resistance and virulence properties have prevailed in Incheon. Nevertheless, some particular populations continue to circulate within the community, providing the evidence for an epidemiological link of C. jejuni infections between humans and food-producing animals. Therefore, the continued monitoring and surveillance of C. jejuni isolates of human and food-producing animal origins are required for public health and food safety.

Genetic diversity of Campylobacter jejuni isolates from Korea and travel-associated cases from east and southeast Asian countries

Forty domestic and travel-associated Campylobacter jejuni isolates were analyzed by profiling 7 pathogenic genes (cdtB, cadF, Cj0131, ciaB, racR, wlaN, and virB11) along with multilocus sequence typing (MLST) and antimicrobial susceptibility testing. cdtB, cadF, and Cj0131 were present in all isolates, whereas virB11 was not detected in either domestic or travel-associated isolates. ciaB was present in all domestic isolates and 94% of travel-associated isolates. The respective detection rates of racR and wlaN in domestic and travel-associated isolates were 94% and 71% and 35.3% and 23%, respectively. MLST analyses of the 40 isolates generated 25 different sequence types (STs). ST-443 (12 isolates) and ST-21 (8 isolates) were dominant among the domestic isolates; however, STs varied among travel-associated isolates. Nalidixic acid, tetracycline, and ciprofloxacin resistance rates of the 40 isolates were 100% (40/40), 95% (38/40), and 88% (35/40), respectively. Domestic isolates exhibited 2-fold higher ciprofloxacin, telithromycin, and chloramphenicol resistance rates than travel-associated isolates. These results indicate a diverse genetic background for travel-associated C. jejuni and suggest that this pathogen may be an important emerging public health threat to travelers.

Antimicrobial susceptibility profiles and molecular typing of Campylobacter jejuni and Campylobacter coli isolates from ducks in South Korea

Campylobacter is a food-borne zoonotic pathogen that causes human gastroenteritis worldwide. Campylobacter bacteria are commensal in the intestines of many food production animals, including ducks and chickens. The objective of the study was to determine the prevalence of Campylobacter species in domestic ducks, and the agar dilution method was used to determine resistance of the isolates to eight antibiotics. In addition, multilocus sequence typing (MLST) was performed to determine the sequence types (STs) of selected Campylobacter isolates. Between May and September 2012, 58 duck farms were analyzed, and 56 (96.6%) were positive for Campylobacter. Among the isolates, 82.1% were Campylobacter jejuni, 16.1% were C. coli, and one was unidentified by PCR. Of the 46 C. jejuni isolates, 87.0%, 10.9%, and 21.7% were resistant to ciprofloxacin, erythromycin, and azithromycin, respectively. Among the C. coli isolates, all 9 strains were resistant to ampicillin, and 77.8% and 33.3% were resistant to ciprofloxacin and azithromycin, respectively. The majority of the Campylobacter isolates were classified as multidrug resistant. Twenty-eight STs were identified, including 20 STs for C. jejuni and 8 STs for C. coli. The most common clonal complexes in C. jejuni were the ST-21 complex and the ST-45 complex, while the ST-828 complex predominated in C. coli. The majority of isolates were of STs noted in ducks and humans from earlier studies, along with seven STs previously associated only with human disease. These STs overlapped between duck and human isolates, indicating that Campylobacter isolates from ducks should be considered potential sources of human infection.