RESUMO
Extended-spectrum ß-lactamase (ESBL)-producing Salmonella is emerging as a worldwide public health concern. In this study, we aimed to investigate the antimicrobial resistance profiles and molecular characteristics of ESBL-producing Salmonella enterica serovar Typhimurium (S. Typhimurium). We obtained a total of 995 S. Typhimurium isolates from the feces and carcasses of pigs (n = 678), chickens (n = 202), and cattle (n = 115) during 2010-2021 in Korea. We found that 35 S. Typhimurium isolates (3.5%) showed resistance to ceftiofur: pigs (51.4%, 18/35) and cattle (42.9%, 15/35). All of the ceftiofur-resistant S. Typhimurium isolates demonstrated multidrug resistance. Moreover, ceftiofur-resistant S. Typhimurium isolates displayed significantly higher rates of resistance to chloramphenicol and trimethoprim/sulfamethoxazole than ceftiofur-susceptible S. Typhimurium isolates (p < 0.05). The ceftiofur-resistant S. Typhimurium isolates produced four different CTX-M-type ß-lactamase, comprising blaCTX-M-55 in the majority (51.4%, 18/35), followed by blaCTX-M-65 (28.6%, 10/35), blaCTX-M-14 (17.1%, 6/35), and blaCTX-M-1 (2.9%, 1/35). Among the 35 ceftiofur-resistant S. Typhimurium isolates, 16 blaCTX-M-55-positive isolates and one blaCTX-M-1-positive isolate were transferred to recipient Escherichia coli RG488 by conjugation. The predominantly found transposable units were blaCTX-M-55-orf477 (45.7%, 16/35), followed by blaCTX-M-65-IS903 (28.6%, 10/35) and blaCTX-M-14-IS903 (17.1%, 6/35). Ceftiofur-resistant S. Typhimurium represented 19 types, with types P1-19 (22.9%, 8/35) and P12-34 (22.9%, 8/35) making up the majority and being found in most farms nationwide. Sequence types (STs) were different by animal species: ST19 (48.6%, 17/35) and ST34 (42.9%, 15/35) were mostly found STs in pigs and cattle, respectively. These findings showed that food animals, especially pigs and cattle, act as reservoirs of blaCTX-M-harboring S. Typhimurium that can potentially be spread to humans.
RESUMO
Antimicrobial-resistant bacteria isolated from food animals pose a major health threat to the public on this planet. This study aimed to determine the susceptibility profiles of Escherichia coli isolated from cattle and pig fecal samples and investigate the molecular characteristics of extended-spectrum ß-lactamase (ESBL)-producing E. coli using gene identification, conjugation, and Southern blot approach. Overall 293 E. coli were recovered from cattle (120 isolates) and pigs (173 isolates) in 7 provinces of Korea during 2017-2018. Ampicillin, chloramphenicol, streptomycin, and sulfisoxazole resistance rates were the highest in pigs' isolates (>60%, p ≤ 0.001) compared to that in cattle (3-39%). Multidrug resistance (MDR) was higher in pig isolates (73%) than in cattle (31%), and the MDR profile usually includes streptomycin, sulfisoxazole, and tetracycline. Resistance to critically important antimicrobials such as ceftiofur, colistin, and ciprofloxacin was higher in weaners than those from finishers in pigs. The qnrS gene was detected in 13% of the pig isolates. Eight isolates from pigs and one isolate from cattle were identified as ESBL-producers and ESBL genes belonged to blaCTX-M-55 (n = 4), blaCTX-M-14 (n = 3), and blaCTX-M-65 (n = 2). Notably, the blaCTX-M-65 and qnrS1 genes were found to be carried together in an identical plasmid (IncHI2) in two isolates from finisher pigs. The blaCTX-M-carrying isolates belonged to phylogenetic groups B1 (n = 4), B2 (n = 2), A (n = 2), and D (n = 1). The blaCTX-M genes and non-ß-lactam resistance traits were transferred to the E. coli J53 recipient from seven blaCTX-M-positive strains isolated from pigs. The blaCTX-M genes belonged to the IncI1α, IncFII, and IncHI2 plasmids and are also associated with the ISEcp1, IS26, IS903, and orf477 elements. These findings suggested the possibility of blaCTX-M-carrying E. coli transmission to humans through direct contact with cattle and pigs or contamination of food products.
Assuntos
Anti-Infecciosos , Infecções por Escherichia coli , Animais , Bovinos , Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , beta-Lactamases/genética , Farmacorresistência Bacteriana/genética , Escherichia coli , Infecções por Escherichia coli/epidemiologia , Infecções por Escherichia coli/veterinária , Infecções por Escherichia coli/microbiologia , Filogenia , Plasmídeos/genética , República da Coreia/epidemiologia , Estreptomicina/farmacologia , Sulfisoxazol/farmacologia , SuínosRESUMO
Extended-spectrum ß-lactamase (ESBL)-producing Salmonella enterica serovar Enteritidis has emerged as a public health concern. The main objectives of this study were therefore to determine the antimicrobial susceptibility profiles of Salmonella Enteritidis and to investigate the molecular characteristics of identified ESBL-producing isolates. In the study, 237 Salmonella Enteritidis isolates (232 isolates from chickens, 4 from cattle, and 1 from a pig) were recovered from carcasses and fecal samples of healthy and diseased food animals between 2010 and 2017. Ceftiofur resistance was noted only in chicken isolates (43%, 102/237), with the highest in healthy chickens and their carcasses (48.3%, 83/172) compared with that in diseased chickens (31.7%, 19/60). All of the ceftiofur-resistant isolates exhibited resistance to multiple antimicrobials. Indeed, a relatively higher percentage of ceftiofur-resistant isolates demonstrated resistance to the tested aminoglycosides and tetracycline compared with the ceftiofur-susceptible strains. In this study, blaCTX-M-15 was the only ESBL gene detected in all of the ceftiofur-resistant isolates. The blaCTX-M-15-carrying isolates belonged to 11 different pulsotypes. The blaCTX-M-15 gene was transferred from 20.6% (21/102) of the blaCTX-M-15-harboring isolates to a recipient Escherichia coli J53. The coexistence of IncHI2/ST2 and IncFIIs/ST1 plasmids was noted in the majority (81.8%, 18/22) of the transconjugants. E. coli J53 transconjugants carrying blaCTX-M-15 gene showed distinct genetic environments, predominantly ISEcp1-blaCTX-M-15-orf477 (15/21, 71.4%). This study demonstrated that healthy chickens and their carcasses act as reservoirs of blaCTX-M-15-carrying Salmonella Enteritidis that can potentially be transmitted to humans.
Assuntos
Infecções por Escherichia coli , Salmonella enterica , Animais , Bovinos , Humanos , Aminoglicosídeos , Antibacterianos/farmacologia , beta-Lactamases/genética , Galinhas , Farmacorresistência Bacteriana Múltipla/genética , Escherichia coli , Proteína 1 Semelhante a Receptor de Interleucina-1 , Salmonella enterica/genética , Salmonella enteritidis/genética , Suínos , Tetraciclinas , República da CoreiaRESUMO
Contamination of meat with antimicrobial-resistant bacteria represents a major public health threat worldwide. In this study, we determined the antimicrobial resistance profiles and resistance trends of Staphylococcus aureus isolated from major food animal carcasses (408 cattle, 1196 pig, and 1312 chicken carcass isolates) in Korea from 2010 to 2018. Approximately 75%, 92%, and 77% of cattle, pig, and chicken carcass isolates, respectively, were resistant to at least one antimicrobial agent. Resistance to penicillin (62.1%) was the highest, followed by resistance to tetracycline (42.1%) and erythromycin (28.2%). About 30% of pig and chicken isolates were resistant to ciprofloxacin. We observed linezolid resistance only in pig isolates (2.3%). However, all S. aureus isolates were sensitive to rifampin and vancomycin. We noted an increasing but fluctuating trend of kanamycin and penicillin resistance in cattle isolates. Similarly, the chloramphenicol, ciprofloxacin, tetracycline, and trimethoprim resistance rates were increased but fluctuated through time in pig isolates. Methicillin-resistant S. aureus (MRSA) accounted for 5%, 8%, and 9% of the cattle, pig, and chicken isolates, respectively. The MRSA strains exhibited significantly high resistance rates to most of the tested antimicrobials, including ciprofloxacin, erythromycin, and tetracycline compared with methicillin-susceptible S. aureus (MSSA) strains. Notably, a relatively high percentage of MRSA strains (5.2%) recovered from pig carcasses were resistant to linezolid compared with MSSA strains (2.1%). In addition, almost 37% of the isolates were multi-drug resistant. S. aureus isolates recovered from major food animal carcasses in Korea exhibited resistance to clinically important antimicrobials, posing a public health risk.
Assuntos
Farmacorresistência Bacteriana , Microbiologia de Alimentos/estatística & dados numéricos , Carne/microbiologia , Staphylococcus aureus/isolamento & purificação , Animais , Bovinos/microbiologia , Galinhas/microbiologia , Testes de Sensibilidade Microbiana , Vigilância da População , República da Coreia , Suínos/microbiologiaRESUMO
The widespread of carbapenem-resistant Acinetobacter baumannii (CRAB) is of great concern in clinical settings worldwide. It is urgent to develop new therapeutic agents against this pathogen. This study aimed to evaluate the therapeutic potentials of compound 62520, which has been previously identified as an inhibitor of the ompA promoter activity of A. baumannii, against CRAB isolates, both in vitro and in vivo. Compound 62520 was found to inhibit the ompA expression and biofilm formation in A. baumannii ATCC 17978 at sub-inhibitory concentrations in a dose-dependent manner. These inhibitory properties were also observed in clinical CRAB isolates belonging to sequence type (ST) 191. Additionally, compound 62520 exhibited a bacteriostatic activity against clinical clonal complex (CC) 208 CRAB isolates, including ST191, and ESKAPE pathogens. This bacteriostatic activity was not different between STs of CRAB isolates. Bacterial clearance was observed in mice infected with bioimaging A. baumannii strain 24 h after treatment with compound 62520. Compound 62520 was shown to significantly increase the survival rates of both immunocompetent and neutropenic mice infected with A. baumannii ATCC 17978. This compound also increased the survival rates of mice infected with clinical CRAB isolate. These results suggest that compound 62520 is a promising scaffold to develop a novel therapeutic agent against CRAB infections.
Assuntos
Infecções por Acinetobacter/prevenção & controle , Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Proteínas da Membrana Bacteriana Externa/genética , Carbapenêmicos/farmacologia , Farmacorresistência Bacteriana Múltipla/efeitos dos fármacos , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/genética , Acinetobacter baumannii/fisiologia , Animais , Antibacterianos/administração & dosagem , Proteínas da Membrana Bacteriana Externa/metabolismo , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Farmacorresistência Bacteriana Múltipla/genética , Feminino , Humanos , Camundongos Endogâmicos BALB C , Testes de Sensibilidade Microbiana/métodos , Regiões Promotoras Genéticas/genética , Bibliotecas de Moléculas Pequenas/administração & dosagem , Bibliotecas de Moléculas Pequenas/farmacologia , Análise de SobrevidaRESUMO
Bioluminescence imaging is a non-invasive tool for in vivo real-time monitoring of infectious disease progression in animal models. However, no bioluminescence imaging assay has been developed to monitor Acinetobacter baumannii infections. In the current study, bioluminescent strains of A. baumannii ATCC 17978 and its isogenic ΔompA mutant were constructed by integrating the promoter of the ompA gene and the luxCDABE luciferase gene into the bacterial chromosome. In an acute murine pneumonia model, bioluminescence of the two reporter strains was clearly visible in the lungs and the bioluminescent signal increased over time. Bioluminescence was correlated with bacterial burden and histopathology in reporter strain-infected mice, suggesting that bioluminescent bacteria are useful for monitoring A. baumannii infections in animal models.
Assuntos
Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/fisiologia , Medições Luminescentes/métodos , Pneumonia/microbiologia , Acinetobacter baumannii/química , Acinetobacter baumannii/genética , Animais , Modelos Animais de Doenças , Feminino , Humanos , Proteínas Luminescentes/química , Proteínas Luminescentes/genética , Proteínas Luminescentes/metabolismo , Camundongos , Camundongos Endogâmicos BALB CRESUMO
Coagulase-negative staphylococci (CNS) are one of the most common bovine mastitis pathogens found worldwide. In this study, we investigated the prevalence and distribution of CNS species in mastitis milk samples and further characterized the methicillin-resistant (MR) CNS. A total of 311 CNS were isolated from 3,692 quarter milk samples from 1,373 dairy cattle at 81 farms between 2013 and 2017. Further evaluation of the CNS isolates revealed 14 CNS species among the samples and 3 predominant species-namely, Staphylococcus chromogenes, Staphylococcus simulans, and Staphylococcus epidermidis. Resistance was higher in S. epidermidis than in other CNS species except for resistance against oxacillin in Staphylococcus sciuri. Resistance to ß-lactams was the most common in all CNS species (8.4% in ampicillin, 21.2% in oxacillin, and 13.5% in penicillin). Conversely, only minimal resistance to cephalothin, ceftiofur, and pirlimycin/novobiocin was found. Twenty-one isolates from 4 species were mecA-carrying MRCNS strains, including 18 S. epidermidis and 1 each of S. sciuri, Staphylococcus equorum, and Staphylococcus hominis. The majority of the mecA-carrying MRCNS isolates were produced in the biofilm. Furthermore, multidrug-resistant sequence type 179 isolate produced the strongest biofilm. Seven genotypes were detected in the 18 MR S. epidermidis strains, the most predominant of which persisted on a farm for 2 yr. Our findings for the antimicrobial susceptibility profiles and genotypic characterization of the MRCNS isolates could provide valuable information for controlling the spread of resistance and the selection of appropriate antimicrobial therapies for mastitis in the future. Further, strategic antibiotic use for mastitis treatment and hygienic management practices aimed at the prevention of the growth of resistant bacteria are urgently needed on dairy farms.
Assuntos
Antibacterianos/farmacologia , Coagulase/genética , Mastite Bovina/microbiologia , Leite/microbiologia , Infecções Estafilocócicas/veterinária , Staphylococcus/efeitos dos fármacos , Animais , Bovinos , Farmacorresistência Bacteriana , Fazendas , Feminino , Genótipo , Mastite Bovina/epidemiologia , Oxacilina/farmacologia , Prevalência , República da Coreia/epidemiologia , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/microbiologia , Staphylococcus epidermidis/efeitos dos fármacosRESUMO
Ducks are potential carriers of pathogenic bacteria, which are capable of transmitting zoonotic diseases to humans. The global spread of Enterobacteriaceae carrying extended-spectrum ß-lactamase (ESBL) genes is a public health concern. This study investigated the prevalence of antimicrobial resistance in Escherichia coli isolated from ducks in Korea and described the molecular characteristics of the ESBLs they produced. A total of 146 E. coli isolates from 404 duck fecal and carcass samples in 85 duck farms were tested for antimicrobial resistance using the broth dilution method and were further characterized using molecular methods. We observed high resistance rates to tetracycline, trimethoprim/sulfamethoxazole, nalidixic acid, ampicillin, and ciprofloxacin. In total, six ceftiofur-resistant isolates (4.1%) were observed, which produced CTX-M-55 (n = 3) or CTX-M-65 ß-lactamase (n = 3). All CTX-M-producing E. coli isolates were also resistant to ciprofloxacin, with mutations in the quinolone resistance determining region of GyrA (S83L with or without D87N) and ParC (S80I), and three CTX-M-producing E. coli isolates carried plasmid-mediated quinolone resistance (PMQR) genes, qepA (n = 1), qnrS, and acc(6')-Ib-cr (n = 2). The transfer of blaCTX-M genes was observed in one isolate mediated by IncF-family plasmids but not in the co-resistant isolates carrying both blaCTX-M and PMQR genes. Pulsed-field gel electrophoresis and multilocus sequence typing demonstrated that CTX-M-producing isolates were heterogeneous; however, identical isolates were found in different farms and slaughterhouses. This study presents baseline data on antimicrobial resistance of E. coli derived from duck samples and is the first report of CTX-M-55 and CTX-M-65 ß-lactamase-producing E. coli isolated from ducks in Korea. The dissemination of ESBL-producing E. coli poses a potential risk to public health and therefore should be monitored.
Assuntos
Antibacterianos/farmacologia , Patos/microbiologia , Proteínas de Escherichia coli/efeitos dos fármacos , beta-Lactamases/efeitos dos fármacos , Animais , Antibacterianos/uso terapêutico , Farmacorresistência Bacteriana/genética , Eletroforese em Gel de Campo Pulsado , Infecções por Escherichia coli/microbiologia , Proteínas de Escherichia coli/isolamento & purificação , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , Zoonoses/microbiologia , beta-Lactamases/isolamento & purificaçãoRESUMO
OBJECTIVES: Acinetobacter baumannii outer membrane protein A (AbOmpA) is involved in bacterial pathogenesis. However, the role of AbOmpA in the antimicrobial resistance of A. baumannii has not been fully elucidated. This study aimed to investigate the role of the OmpA-like domain of AbOmpA in the antimicrobial resistance of A. baumannii. METHODS: The MICs of antimicrobial agents for the WT A. baumannii ATCC 17978, ΔompA mutant, OmpA-like domain-deleted (amino acids 223-356) AbOmpA mutant and single-copy ompA-complemented strain were determined by the Etest method. The MICs of antimicrobial agents for MDR strain 1656-2 and its ΔompA mutant strains were also determined. RESULTS: The ΔompA mutant strain of ATCC 17978 was more susceptible to trimethoprim (>5.3-fold) and other antimicrobial agents tested (<2.0-fold), except tigecycline, than the WT strain. The ΔompA mutant strain of 1656-2 was more susceptible to trimethoprim (>4.0-fold), tetracycline (2.3-fold) and other antimicrobial agents (<2.0-fold), including tigecycline, colistin and imipenem, than the WT strain. The MICs of gentamicin, imipenem and nalidixic acid for the WT ATCC 17978 and ΔompA mutant strains were decreased in the presence of an efflux pump inhibitor. A mutant strain of ATCC 17978 with the OmpA-like domain of AbOmpA deleted was more susceptible (≥2.0-fold) to substrates of the resistance-nodulation-division efflux pumps, including aztreonam, gentamicin, imipenem and trimethoprim, than the WT strain. CONCLUSIONS: This study demonstrates that AbOmpA contributes to the antimicrobial resistance of A. baumannii through the OmpA-like domain.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Proteínas da Membrana Bacteriana Externa/química , Proteínas da Membrana Bacteriana Externa/metabolismo , Farmacorresistência Bacteriana Múltipla , Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/genética , Acinetobacter baumannii/patogenicidade , Proteínas da Membrana Bacteriana Externa/genética , Colistina/farmacologia , Deleção de Genes , Regulação Bacteriana da Expressão Gênica , Humanos , Imipenem/farmacologia , Testes de Sensibilidade Microbiana , Mutação/efeitos dos fármacos , Domínios Proteicos , Trimetoprima/farmacologiaRESUMO
Clostridium difficile is the most common etiological agent of antibiotic-associated diarrhea in hospitalized and non-hospitalized patients. This study investigated the secretion of membrane vesicles (MVs) from C. difficile and determined the expression of pro-inflammatory cytokine genes and cytotoxicity of C. difficile MVs in epithelial cells in vitro. C. difficile ATCC 43255 and two clinical isolates secreted spherical MVs during in vitro culture. Proteomic analysis revealed that MVs of C. difficile ATCC 43255 contained a total of 262 proteins. Translation-associated proteins were the most commonly identified in C. difficile MVs, whereas TcdA and TcdB toxins were not detected. C. difficile ATCC 43255-derived MVs stimulated the expression of pro-inflammatory cytokine genes, including interleukin (IL)-1ß, IL-6, IL-8, and monocyte chemoattractant protein-1 in human colorectal epithelial Caco-2 cells. Moreover, these extracellular vesicles induced cytotoxicity in Caco-2 cells. In conclusion, C. difficile MVs are important nanocomplexes that elicit a pro-inflammatory response and induce cytotoxicity in colonic epithelial cells, which may contribute, along with toxins, to intestinal mucosal injury during C. difficile infection.
Assuntos
Proteínas de Bactérias/toxicidade , Toxinas Bacterianas/toxicidade , Clostridioides difficile/metabolismo , Colo/patologia , Citocinas/efeitos dos fármacos , Citocinas/genética , Enterotoxinas/toxicidade , Células Epiteliais/efeitos dos fármacos , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Células CACO-2/efeitos dos fármacos , Técnicas de Cultura de Células , Quimiocina CCL2/efeitos dos fármacos , Quimiocina CCL2/genética , Clostridioides difficile/genética , Enterocolite Pseudomembranosa/metabolismo , Enterotoxinas/genética , Enterotoxinas/metabolismo , Citometria de Fluxo , Regulação da Expressão Gênica/efeitos dos fármacos , Células Hep G2/efeitos dos fármacos , Humanos , Interleucina-1beta/efeitos dos fármacos , Interleucina-1beta/genética , Interleucina-6/genética , Interleucina-8/efeitos dos fármacos , Interleucina-8/genética , Mucosa Intestinal/efeitos dos fármacos , Microscopia Eletrônica de Transmissão , ProteômicaRESUMO
Staphylococcus aureus secretes membrane-derived vesicles (MVs), which can deliver virulence factors to host cells and induce cytopathology. However, the cytopathology of host cells induced by MVs derived from different S. aureus strains has not yet been characterized. In the present study, the cytotoxic activity of MVs from different S. aureus isolates on host cells was compared and the proteomes of S. aureus MVs were analyzed. The MVs purified from S. aureus M060 isolated from a patient with staphylococcal scalded skin syndrome showed higher cytotoxic activity toward host cells than that shown by MVs from three other clinical S. aureus isolates. S. aureus M060 MVs induced HEp-2 cell apoptosis in a dose-dependent manner, but the cytotoxic activity of MVs was completely abolished by treatment with proteinase K. In a proteomic analysis, the MVs from three S. aureus isolates not only carry 25 common proteins, but also carry ≥60 strain-specific proteins. All S. aureus MVs contained δ-hemolysin (Hld), γ-hemolysin, leukocidin D, and exfoliative toxin C, but exfoliative toxin A (ETA) was specifically identified in S. aureus M060 MVs. ETA was delivered to HEp-2 cells via S. aureus MVs. Both rETA and rHld induced cytotoxicity in HEp-2 cells. In conclusion, MVs from clinical S. aureus isolates differ with respect to cytotoxic activity in host cells, and these differences may result from differences in the MV proteomes. Further proteogenomic analysis or mutagenesis of specific genes is necessary to identify cytotoxic factors in S. aureus MVs.
Assuntos
Proteoma/metabolismo , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/metabolismo , Vesículas Transportadoras/metabolismo , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Humanos , Transporte Proteico , Proteoma/genética , Proteômica , Staphylococcus aureus/genética , Staphylococcus aureus/patogenicidade , Vesículas Transportadoras/genética , VirulênciaRESUMO
Anti-virulence therapeutic strategies are promising alternatives against drug-resistant pathogens. Outer membrane protein A (OmpA) plays a versatile role in the pathogenesis and antimicrobial resistance of Acinetobacter baumannii. Therefore, OmpA is an innovative target for anti-virulence therapy against A. baumannii. This study aimed to develop a high-throughput screening (HTS) system to discover small molecules inhibiting the ompA promoter activity of A. baumannii and screen chemical compounds using the bacterial growth-based HTS system. The ompA promoter and open reading frame of nptI fusion plasmids that controlled the expression of nptI encoding resistance to kanamycin by the ompA promoter were constructed and then transformed into A. baumannii ATCC 17978. This reporter strain was applied to screen small molecules inhibiting the ompA promoter activity in a chemical library. Of the 7,520 chemical compounds, 15 exhibited ≥ 70% growth inhibition of the report strain cultured in media containing kanamycin. Three compounds inhibited the expression of ompA and OmpA in the outer membrane of A. baumannii ATCC 17978, which subsequently reduced biofilm formation. In conclusion, our reporter strain is useful for large-scale screening of small molecules inhibiting the ompA expression in A. baumannii. Hit compounds identified by the HTS system are promising scaffolds to develop novel therapeutics against A. baumannii.
Assuntos
Infecções por Acinetobacter/microbiologia , Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Proteínas da Membrana Bacteriana Externa/metabolismo , Biofilmes/efeitos dos fármacos , Regiões Promotoras Genéticas/efeitos dos fármacos , Bibliotecas de Moléculas Pequenas/farmacologia , Acinetobacter baumannii/genética , Acinetobacter baumannii/patogenicidade , Acinetobacter baumannii/fisiologia , Proteínas da Membrana Bacteriana Externa/genética , Avaliação Pré-Clínica de Medicamentos , Regulação Bacteriana da Expressão Gênica/efeitos dos fármacos , Humanos , Virulência/efeitos dos fármacosRESUMO
Staphylococcus aureus is among the most common zoonotic pathogens that cause foodborne illnesses worldwide. The main objectives of the current study were therefore to determine the antimicrobial susceptibility profiles of S. aureus isolated from goats in Korea and to investigate the molecular characteristics of identified methicillin-resistant S. aureus (MRSA). In the study, 481 S. aureus isolates (431 from the nasal cavity and 50 from carcass) were recovered from 1146 carcasses and nasal swabs between July 2018 and January 2019. Approximately 82% and 72.6% of nasal and carcass isolates, respectively, were resistant to at least one antimicrobial agent, with the highest rate of resistance to penicillin, followed by resistance to chloramphenicol and tetracycline. Relatively small proportions of the isolates were resistant to cefoxitin, clindamycin, and erythromycin. However, all S. aureus isolates were sensitive to linezolid, rifampin, and vancomycin. Six MRSA isolates were obtained, three each from the nasal cavity and carcass. MRSA isolates were of two sequence types (ST) (ST72 and ST398), three spa types (t664, t324, and t571), and two SCCmec types (IV and V). The ST72 MRSA isolates had identical PFGE profiles. In addition, ST72 MRSA-SCCmec IV isolates carried at least six staphylococcal leukotoxin- and enterotoxin-encoding genes (lukED, seg, sei, sem, sen, seo, and seq). The remaining ST398 isolate carried only the lukED gene and was additionally resistant to eight non-ß-lactam antibiotics. To the best of our knowledge, this is the first report of MRSA from goats in Korea. There is a possibility of transmission of MRSA from goat to human or contamination of food products. Therefore, regular microbiological investigation in goats, farms, and slaughterhouses is critical to determine the existence of virulent and multi-drug resistant (MDR) S. aureus and to implement preventive strategies.
Assuntos
Microbiologia de Alimentos , Cabras/microbiologia , Staphylococcus aureus Resistente à Meticilina/genética , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Animais , Antibacterianos/farmacologia , Enterotoxinas , Exotoxinas , Fazendas , Doenças Transmitidas por Alimentos/microbiologia , Humanos , Testes de Sensibilidade Microbiana , Leite/microbiologia , República da Coreia , Infecções Estafilocócicas/microbiologiaRESUMO
We aimed to investigate the presence of the phenicol-oxazolidinone resistance gene poxtA in linezolid-resistant enterococci from food-producing animals and analyze its molecular characteristics. We collected 3941 Enterococcus faecium and 5088 E. faecalis isolates from all provinces of South Korea from 2008 to 2018. We found linezolid resistance in 0.79% (94/3941) of E. faecium and 1.22% (62/5088) of E. faecalis isolates. Overall, 23.1% (36/156) of the linezolid-resistant isolates had the poxtA gene, including 31 E. faecium and five E. faecalis isolates. The poxtA-positive enterococci were mainly isolated from chicken (86.1%; 26/36). Fifteen poxtA-harboring isolates co-carried another linezolid-resistance gene, optrA. Eight E. faecium isolates had an N130K mutation in the ribosomal protein L4, while no mutations were observed in E. faecalis isolates. The poxtA gene was transferred into 10 enterococci by conjugation. Multi-locus sequence typing (MLST) and pulsed-field gel electrophoresis (PFGE) analysis indicated that poxtA-carrying isolates were heterogeneous. Three E. faecium isolates belonged to CC17 (ST32, ST121, and ST491). To our knowledge, this is the first report on the poxtA gene in Korea. Prudent use of antimicrobials and active surveillance on antimicrobial resistance are urgently needed to reduce the risk of dissemination of the linezolid-resistant isolates in humans and animals.
RESUMO
Global dissemination of non-typhoidal Salmonella producing extended-spectrum ß-lactamase (ESBL) is a public-health concern. Recently, the prevalence of Salmonella spp. resistant to third-generation cephalosporins has been increasing in food-producing animals in Korea. In this study, we investigated resistance mechanisms and molecular characteristics of S. Virchow isolates resistant to extended-spectrum cephalosporins (ESCs). We obtained 265 S. Virchow isolates from fecal and carcasses samples of cattle (n = 2), pigs (n = 7), and chickens (n = 256) during 2010-2017, and observed high ESC-resistance (63.8%, 169/265); most of the resistant isolates (96.4%) were obtained from chickens. ESC-resistant S. Virchow isolates (n = 169) showed significantly higher resistance rates to other antimicrobials (especially aminoglycosides and tetracycline, p-value <0.0001), as well as prevalence of multidrug resistance, than did ESC-susceptible S. Virchow isolates (n = 96). All ESC-resistant S. Virchow produced CTX-M-15-type ESBL (n = 147) and/or CMY-2-type AmpC ß-lactamase (n = 23). ESC-resistant S. Virchow represented seven pulsotypes, predominantly composed of type II (58.6%) and III (26.0%), detected in 69 farms in 10 provinces, and 33 farms in 7 provinces, respectively. Genes encoding ESC-resistance were horizontally transferred by conjugation to recipient E. coli J53; this was demonstrated in 28.8% (42/146) of blaCTX-M-15-positive isolates and in 50.0% (11/22) of blaCMY-2-positive isolates. All conjugative plasmids carrying blaCTX-M-15 and blaCMY-2 genes belonged to ST2-IncHI2 and ST12/CC12-IncI1, respectively. Genetic features of transferred bla genes were involved with ISEcp1 in both blaCTX-M-15 and blaCMY-2; ISEcp1 plays a critical role in the efficient capture, expression, and mobilization of bla genes. In addition to blaCTX-M-15 genes, resistance markers to aminoglycosides and/or tetracycline were co-transferred to recipient E. coli J53. Our results show a high prevalence of ESBL-producing S. Virchow in chickens and chicken carcasses. Specific blaCTX-M-15 and blaCMY-2-carrying S. Virchow clones and plasmids were predominant in food-producing animals nationwide. Restriction of antimicrobial use and proper biosecurity practices at the farm level should be urgently implemented in the poultry industry.
Assuntos
Microbiologia de Alimentos , Salmonella enterica/enzimologia , Salmonella enterica/isolamento & purificação , beta-Lactamases/genética , Animais , Antibacterianos/farmacologia , Proteínas de Bactérias , Bovinos/microbiologia , Cefalosporinas/farmacologia , Galinhas/microbiologia , Farmacorresistência Bacteriana/efeitos dos fármacos , Farmacorresistência Bacteriana/genética , Plasmídeos/genética , Aves Domésticas/microbiologia , República da Coreia , Salmonella enterica/efeitos dos fármacos , Salmonella enterica/genética , Sorogrupo , Suínos/microbiologia , beta-Lactamases/metabolismoRESUMO
Food-producing animals are considered a leading source of human Salmonella infections in Korea. However, there is a lack of comprehensive and up-to-date data regarding the diversity and resistance profiles of Salmonella serotypes in these animals. Therefore, this study aimed to determine the distribution and antimicrobial resistance profiles of Salmonella serotypes isolated from cattle, pigs, and chickens in Korea between 2010 and 2018. A total of 3018 Salmonella isolates were obtained from 16 laboratories/centers participating in the Korean Veterinary Antimicrobial Resistance Monitoring System. Salmonella serotypes were identified from the following isolates: 179 cattle (17 serotypes), 959 pig (45 serotypes), and 1880 chicken (64 serotypes). The most frequent serotypes in cattle (Typhimurium, Salmonella 4,[5],12:i:-, and Schwarzengrund), pigs (Typhimurium, Rissen, and S. 4,[5],12:i:-), and chickens (Enteritidis, Albany, Virchow, and Montevideo) accounted for more than 50% of the total serotypes in the respective animal species. To the best of our knowledge, Salmonella 4,[5],12:i:- has not been identified in cattle in Korea to date. More than 80% of the isolates demonstrated resistance to at least one antimicrobial agent. Multidrug-resistance was found in almost half of the serotypes; the highest proportion in cattle (59.2%), followed by pigs (53.4%), and chickens (45.7%). Significant proportions of the serotypes were resistant to ampicillin, streptomycin, and tetracycline. Ceftiofur and ciprofloxacin resistance rates were the highest in Salmonella isolated from chickens (17.1% and 4.1%, respectively) and cattle (10.1% and 3.9%, respectively) compared to that in pigs. Among the frequent serotypes, Albany demonstrated the highest resistance rate (>90%) to five different antimicrobials. Alarmingly, some Salmonella serotypes that are frequently associated with human infections demonstrated a trend of increasing resistance to critically important antibiotics, including 3rd generation cephalosporins and quinolones. Collectively, the presence of antibiotic-resistant Salmonella in food-producing animals poses a potential risk to public health.
Assuntos
Antibacterianos/farmacologia , Farmacorresistência Bacteriana , Salmonelose Animal/microbiologia , Salmonella/classificação , Salmonella/efeitos dos fármacos , Animais , Bovinos , Galinhas , Farmacorresistência Bacteriana/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , República da Coreia/epidemiologia , Salmonella/isolamento & purificação , Salmonelose Animal/epidemiologia , Sorogrupo , SuínosRESUMO
We examined the prevalence and molecular characteristics of mcr-3 carrying colistin-resistant Escherichia coli among cattle, pig, and chicken isolates in South Korea. Among a total of 185 colistin-resistant E. coli isolates determined in this study (47 from cattle, 90 from pigs, and 48 from chicken), PCR amplification detected mcr-3 genes in 17 isolates predominantly from diseased pigs. The mcr-3 genes were characterized as mcr-3.1 in 15 isolates and mcr-3.5 in 2 isolates. The mcr-3 gene was transferred to the E. coli J53 recipient strain from more than 50% of the mcr-3-carrying isolates. The mcr-3.1 and mcr-3.5 genes were identified predominantly in IncHI2 and IncP plasmids, respectively. Multi-locus sequence typing analysis revealed eight previously reported sequence types (ST), including ST1, ST10, and ST42. We identified isolates with similar pulsed-field gel electrophoresis patterns from diseased pigs in three farms. Besides, the isolates carried various virulence factors and demonstrated resistance to multiple antimicrobials, including ß-lactams and quinolones. Further, the mcr-3.5 encodes three amino acid substitutions compared with mcr-3.1. To the best of our knowledge, this is the first report of pathogenic E. coli carrying mcr-3.5 in South Korea, which implies that mcr-3 variants may have already been widely spread in the pig industry.
RESUMO
The heavy use or abuse of antimicrobials in food animals has caused an increase in antimicrobial resistance in enterococci of animal origin, which could get transmitted to those of human origin via the food chain. Since duck meat consumption has been on the rise in Korea, we conducted this study to provide information about the antimicrobial resistance of the enterococci obtained from healthy ducks and their carcasses. A total of 82 Enterococcus faecium and 174 E. faecalis isolated from duck fecal and carcass samples were investigated for antimicrobial resistance to 16 agents, using broth dilution method, and were further characterized using molecular methods. Most of E. faecium (84.1%) and E. faecalis (87.9%) isolates were resistant to one or more antimicrobials. Multi-drug resistant (MDR) isolates were observed in both E. faecium (40.2%) and E. faecalis (33.9%) with high frequencies. High rate of resistance was observed for tetracycline, ciprofloxacin, chloramphenicol, and erythromycin in both E. faecium and E. faecalis. Resistance to gentamicin, vancomycin, and daptomycin, in both E. faecium and E. faecalis, was, if at all, very rare. However, linezolid resistance was observed in nine E. faecium (11.0%) and one E. faecalis (0.6%). All, but one, Linezolid resistant (LR) isolates were also resistant to chloramphenicol and florfenicol. The novel transferable oxazolidinone and phenicol resistant gene, optrA, was found in six E. faecium isolates. All of them co-carried phenicol exporter gene fexA. None of the LR isolates had mutation in the 23S ribosomal RNA and in the ribosomal protein L3. Six LR E. faecium isolates had Asn130Lys mutation in the ribosomal protein L4, of which five also carried optrA gene. None of the isolates carried the multi-resistance gene cfr. Transfer of oxazolidinone and phenicol resistance was observed in five among the 10 LR isolates; two of them had optrA and fexA genes. Multi-drug resistant Enterococcus that also carried the resistance gene to a last-resort antimicrobial is a major concern for public health. Thus, to prevent the introduction of last-resort antimicrobial resistance into food chain, continuous surveillance of antimicrobial resistance in duck is imperative.
Assuntos
Farmacorresistência Bacteriana Múltipla/genética , Patos/microbiologia , Enterococcus faecalis/isolamento & purificação , Enterococcus faecium/isolamento & purificação , Oxazolidinonas/farmacologia , Animais , Antibacterianos/farmacologia , Anti-Infecciosos/farmacologia , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Cloranfenicol/farmacologia , Ciprofloxacina/farmacologia , Enterococcus faecalis/efeitos dos fármacos , Enterococcus faecalis/genética , Enterococcus faecium/efeitos dos fármacos , Enterococcus faecium/genética , Eritromicina/farmacologia , Fezes/microbiologia , Genes Bacterianos , Linezolida/farmacologia , Testes de Sensibilidade Microbiana , Tipagem de Sequências Multilocus , RNA Ribossômico 23S/isolamento & purificação , República da Coreia , Proteína Ribossômica L3 , Tetraciclina/farmacologia , Tianfenicol/análogos & derivados , Tianfenicol/farmacologiaRESUMO
The aim of this study was to screen lead compounds exhibiting potent in vitro antimicrobial activity against multidrug-resistant (MDR) Acinetobacter baumannii strains from a library of chemical compounds. In a high-throughput screening analysis of 7520 compounds representative of 340,000 small molecules, two 4H-4-oxoquinolizine compounds were the most active against A. baumannii ATCC 17978. Subsequent selection and analysis of 70 4H-4-oxoquinolizine compounds revealed that the top 7 compounds were extremely active against extensively drug-resistant (XDR) A. baumannii isolates. These compounds commonly carried a 1-cyclopropyl-7-fluoro-4-oxo-4H-quinolizine-3-carboxylic acid core structure but had different C-8 and/or C-9 moieties. Minimum inhibitory concentrations (MICs) of the seven compounds against fluoroquinolone-resistant A. baumannii isolates were found to be in the range of 0.02-1.70 µg/mL regardless of the mutation types in the quinolone resistance-determining region (QRDR) of GyrA and ParC. Cytotoxicity of the seven compounds was observed in HeLa and U937 cells at a concentration of 50 µg/mL, which was >32.5- to 119-fold higher than the MIC90 for A. baumannii isolates. In conclusion, novel 4H-4-oxoquinolizine compounds represent a promising scaffold on which to develop antimicrobial agents against drug-resistant A. baumannii strains.
Assuntos
Acinetobacter baumannii/efeitos dos fármacos , Antibacterianos/farmacologia , Quinolizinas/farmacologia , Antibacterianos/química , Antibacterianos/toxicidade , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Avaliação Pré-Clínica de Medicamentos , Ensaios de Triagem em Larga Escala , Humanos , Testes de Sensibilidade Microbiana , Quinolizinas/química , Quinolizinas/toxicidadeRESUMO
Clostridium difficile is one of the main etiological agents causing antibiotic-associated diarrhea. This study investigated the genetic diversity of 70 toxigenic C. difficile isolates from two Korean hospitals by employing toxinotyping, ribotyping, multilocus sequence typing (MLST), and pulsed-field gel electrophoresis (PFGE). Toxin gene amplification resulted in 68 AâºB⺠and two A-B+ isolates. Most isolates (95.7-100%) were susceptible to daptomycin, metronidazole, and vancomycin. Seventy C. difficile isolates were classified into five toxinotypes, 19 ribotypes, 16 sequence types (STs), and 33 arbitrary pulsotypes. All C. difficile isolates of ribotype 018 (n = 38) were classified into ST17, which was the most prevalent ST in both hospitals. However, C. difficile isolates of ST17 (ribotype 018) exhibited pulsotypes that differed by hospital. ST2 (ribotype 014/020), 8 (ribotypes 002), 17 (ribotype 018), and 35 (ribotypes 015) were detected in both hospitals, whereas other STs were unique to each hospital. Statistical comparison of the different typing methods revealed that ribotyping and PFGE were highly predictive of STs. In conclusion, our epidemiological study indicates that C. difficile infections in both hospitals are associated with the persistence of endemic clones coupled with the emergence of many unique clones. A combination of MLST with PFGE or ribotyping could be useful for monitoring epidemic C. difficile strains and the emergence of new clones in hospitals.