Streptococci are among the normal human microflora that populate the oral cavity. However, oral streptococci are known as a major causative agent for dental caries and bacterial endocarditis. Tetracycline is a broad-spectrum antibiotic that is used for oral infections but two mechanisms of tetracycline resistance in streptococci have been reported. The tet(K) and tet(L) genes in these bacteria are related to the active efflux of tetracycline, whereas tet(M) and tet(O) confer ribosomal protection from this antibiotic. It has been reported that the tetracycline resistance of streptococci is related mainly to the activity of tet(M) and tet(O). In our present study, we examined the prevalence of tet(M) and tet(O) in oral streptococci isolated from Korean dental plaques using PCR. One hundred and forty eight of 635 isolates (23.3%) were tetracycline resistant; 68 of these strains (46%) harbored tet(M) and 3 strains (2%) were positive for tet(O). However, tet(M) and tet(O) did not co-exist in any of the resistant strains. Seventy seven of the 148 tetracycline resistant strains (52%) were negative for both the tet(M) and tet(O) genes.
Bacteria ; Dental Caries ; Endocarditis, Bacterial ; Humans ; Incidence* ; Mouth ; Polymerase Chain Reaction ; Prevalence ; Tetracycline ; Tetracycline Resistance*

Recently, polymerase chain reaction (PCR)-based methods have been used to reclassify Ureaplasma urealyticum into two independent species (spp.), designating U. parvum and U. urealyticum. In the current study, we aim to reclassify U. urealyticum and to analyze the correlation between the presence of a genetic marker and an antibiotic resistance of U. urealyticum. Susceptibility test against tetracycline, levofloxain or moxifloxacin was performed by broth microdilution method. The presence of tet(M) gene and the mutations of quinolone resistance-determining regions (QRDRs) were analyzed by PCR and sequencing. Among fourteen Ureaplasma isolates, three were identified as U. parvum and eleven were identified as U. urealyticum, and this is first report showing that two independent spp. of U. urealyticum isolated from Korean are present. The minimum inhibitory concentration (MIC) ranges for Ureaplasma isolates were as follows: tetracycline 0.25~128 microg/ml, levofloxacin 1~8 microg/ml, and moxifloxacin 0.5~4 microg/ml. The tet(M) determinant was found in 3 among 14 Ureaplasma isolates with tetracycline MIC of >16 microg/ml, suggesting that the presence of the tet(M) determinant is associated with tetracycline resistance. Mutations of gyrA, gyrB, parC, and parE genes in the QRDRs were found in 3 among 14 Ureaplasma isolates, exhibiting only parE gene mutation is associated with fluoroquinolone resistance.
Aza Compounds ; Drug Resistance, Microbial ; Fluoroquinolones ; Genetic Markers ; Microbial Sensitivity Tests ; Ofloxacin ; Polymerase Chain Reaction ; Quinolines ; Tetracycline ; Tetracycline Resistance ; Ureaplasma ; Ureaplasma urealyticum

The emergence and prevalence of methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-susceptible S. aureus (MSSA) in livestock animals have become a worldwide public health concern. While the prevalence and genetic profiles of MRSA strains in pigs and pork meat have been actively studied, livestock-associated MSSA strains have only been characterized in a few small-scale studies. In this investigation, we assessed the nationwide prevalence of MSSA in the Korean pig production chain, including pig farms, slaughterhouses, and retail markets. Among the 41 MSSA strains, the predominant clonal lineages were sequence type (ST) 398 (n = 15, 37%) and ST5 (n = 13, 32%). Although the overall prevalence of MSSA (2.58%) was low and mostly restricted to pig farms, ST398 MSSA strains showed higher level of multidrug resistance phenotype versus non-ST398 MSSA strains. In addition to the MDR phenotype, all of the ST398 MSSA strains exhibited resistance to tetracycline as they harbored the tet(K), tet(L), and/or tet(M) genes. However, ST398 MSSA strains did not exhibit increased resistance to zinc compared with the non-ST398 strains. This study is the first to provide evidence of ST398 MSSA emergence in livestock animals in Korea. Further studies are necessary to elucidate the potential of ST398 MSSA strains for human transmission. Our findings suggest that the MDR phenotype and high levels of tetracycline resistance may have played an important role in the emergence and prevalence of ST398 MSSA in pig farms in Korea.
Abattoirs ; Agriculture ; Animals ; Drug Resistance, Multiple ; Humans ; Korea ; Livestock ; Meat ; Methicillin-Resistant Staphylococcus aureus ; Phenotype ; Prevalence ; Public Health ; Red Meat ; Staphylococcus aureus ; Staphylococcus ; Swine ; Tetracycline ; Tetracycline Resistance ; Zinc

BACKGROUND: This study is designed to provide data on the trend of resistance by year of isolation in the clinical isolates of group B streptococci(GBS) during recent eight years and to elucidate the relationship between serotypes and antimicrobial resistance patterns. METHODS: The minimal inhibitory concentrations (MIC) of seven antimicrobial agents and serotypes for 150 strains of GBS isolated from clinical specimens between 1990 and 1997 were investigated. RESULTS: The resistance rate of 150 clinical isolates of GBS were 20.0% to clindamycin, 16.0% to erythromycin, 4.0% to chloramphenicol, and 95.3% to tetracycline. None was resistant to penicillin, ceftriaxone, or vancomycin. Of the 24 isolates resistant to erythromycin, 20 (83.3%) were resistant to clindamycin. Resistance rates of erythromycin according to serotypes in decreasing order were 69.2% (V), 23.2% (III), and 3.5% (Ib). All serotypes Ia and II were susceptible to erythromycin and clindamycin. CONCLUSIONS: Striking emergence of resistant strains to erythromycin and clindamycin in our clinical isolates of GBS was mainly due to sudden increase of serotype V and III which shows multi-drug resistance phenotype.
Anti-Infective Agents ; Ceftriaxone ; Chloramphenicol ; Clindamycin ; Drug Resistance, Multiple ; Erythromycin ; Penicillins ; Phenotype ; Strikes, Employee ; Tetracycline ; Vancomycin

OBJECTIVES: To determine the occurrence and antimicrobial resistance of pathogenic vibrios from green mussel, Perna viridis in bacoor bay cavite.

METHODS: Vibrios were isolated using TCBS agar and confirmed using API Identification kit. The relationship between the density of vibrios and environment parameters such as months, harvest sites and other physico-chemical parameters of water was determined. The isolated vibrios were subjected to antibiotic resistance testing to determine the resistance patterns.

RESULTS: Pathogenic vibrios were isolated in all of the 90 mussel samples. Of the 183 vibrio isolates, 75 strains were V. alginolyticus and 53 strains belonged to V. cholerae wherein 18 (34%) of these were V. cholerae serotype O1. Forty nine (49) strains belonged to V. parahaemolyticus and six were V. vulnificus. Using the regression analysis, salinity, water temperature and ph have significant correlation on the density of vibrios (p=0.0309), with regression model, total vibrios = -16990763 + 145858 Salinity + 186808 Temperature + 1037886 pH. In the antimicrobial resistance assay,ampicillin had the highest drug resistance (37.8%) followed by nalidixic acid (10.4%), tetracycline (10.4%) and co-trimoxazole (9.3%).

CONCLUSION: Pathogenic vibrios were isolated in mussel of Bacoor, Cavite and can be predicted using salinity, temperature and pH of the water. Thirty six percent (36%) of Vibrio isolates were resistance to ampicillin.

Objective: To understand the antimicrobial resistance and genome characteristics of Campylobacter isolates recovered from retailed poultry meat samples in 20 provinces in China in 2020. Methods: In 2020, 265 Campylobacter strains including 244 Campylobacter jejuni and 21 Campylobacter coli collected from retailed poultry meat samples in China were tested for antimicrobial resistance to 9 antimicrobial compounds by using the agar dilution method. Forty-two selected isolates were sent for whole genome sequencing and 38 high-quality genomes were analyzed for their antimicrobial resistance genes, virulence genes, sequence types and genetic diversity. Results: The resistance rates of Campylobacter isolates from poultry meats to tetracycline, nalidixic acid and ciprofloxacin were the highest (84%-100%), with 53.2% of the isolates showing multidrug resistance in this study. The resistance rates of C. coli to erythromycin, azithromycin, telithromycin, gentamicin and clindamycin were significantly higher than those of C. jejuni (P<0.05). The resistance genes conferring resistance to β-lactams (100%, 38/38), quinolones (94.7%, 36/38), tetracycline (81.6%, 31/38) and aminoglycosides (50%, 19/38) were the most frequently detected among 38 Campylobacter genomes. C. jejuni carried more virulence genes than C. coli. In total, 19 and 17 sequence types (ST) were obtained from 20 sequenced C. jejuni and 18 C. coli isolates, respectively, including 5 novel STs. The isolates showed a high genetic diversity based on their sequence types. Conclusion: The phenomenon of antimicrobial resistance in Campylobacter from poultry meat sources in China is relatively serious, and resistance and virulence genes are widely distributed in Campylobacter. There is genetic diversity in Campylobacter.
Humans ; Animals ; Anti-Bacterial Agents/pharmacology* ; Campylobacter/genetics* ; Poultry ; Drug Resistance, Bacterial/genetics* ; Genomics ; China ; Tetracycline

Objective: To understand the antimicrobial resistance and genome characteristics of Campylobacter isolates recovered from retailed poultry meat samples in 20 provinces in China in 2020. Methods: In 2020, 265 Campylobacter strains including 244 Campylobacter jejuni and 21 Campylobacter coli collected from retailed poultry meat samples in China were tested for antimicrobial resistance to 9 antimicrobial compounds by using the agar dilution method. Forty-two selected isolates were sent for whole genome sequencing and 38 high-quality genomes were analyzed for their antimicrobial resistance genes, virulence genes, sequence types and genetic diversity. Results: The resistance rates of Campylobacter isolates from poultry meats to tetracycline, nalidixic acid and ciprofloxacin were the highest (84%-100%), with 53.2% of the isolates showing multidrug resistance in this study. The resistance rates of C. coli to erythromycin, azithromycin, telithromycin, gentamicin and clindamycin were significantly higher than those of C. jejuni (P<0.05). The resistance genes conferring resistance to β-lactams (100%, 38/38), quinolones (94.7%, 36/38), tetracycline (81.6%, 31/38) and aminoglycosides (50%, 19/38) were the most frequently detected among 38 Campylobacter genomes. C. jejuni carried more virulence genes than C. coli. In total, 19 and 17 sequence types (ST) were obtained from 20 sequenced C. jejuni and 18 C. coli isolates, respectively, including 5 novel STs. The isolates showed a high genetic diversity based on their sequence types. Conclusion: The phenomenon of antimicrobial resistance in Campylobacter from poultry meat sources in China is relatively serious, and resistance and virulence genes are widely distributed in Campylobacter. There is genetic diversity in Campylobacter.
Humans ; Animals ; Anti-Bacterial Agents/pharmacology* ; Campylobacter/genetics* ; Poultry ; Drug Resistance, Bacterial/genetics* ; Genomics ; China ; Tetracycline

BACKGROUND: Streptococcus pyogenes is the most common bacterial cause of acute pharyngitis in children. The resistance rate and phenotype distribution of S. pyogenes could be different by geo-graphical locations and study periods. The purpose of this study was to determine the minimal inhibitory concentration (MIC), resistance rate to antimicrobial agents, and association of erythromycin (EM) resistance phenotype with resistance to tetracycline (TC) among S. pyogenes isolated in Jinju, Korea. METHODS: A total of 223 isolates of S. pyogenes were obtained from pediatric pharyngitis patients and asymptomatic carriers during the period from November 2001 to May 2002. Antibiotic susceptibility test was performed by the agar dilution and the disk diffusion methods against eight antimicro-bial agents. The phenotypes of EM resistance were determined by the double-disk diffusion test. RESULTS: Resistance rates of S. pyogenes to EM, clindamycin (CC), and TC were 48.9%, 22.0% and 29.6%, respectively. MIC(50) and MIC(90) were 0.25 mg/L and > or =256 mg/L of EM, < or =0.06 mg/L and > or =256 mg/L of CC, and < or =0.5 mg/L and 64 mg/L of TC respectively. Almost all isolates were suscep-tible to penicillin, ampicillin, ofloxacin, levofloxacin and chloramphenicol. The M phenotype (55.0%) was slightly more common than the constitutive resistance (45.0%); the inducible resistance pheno-type was not detected. All strains of constitutive resistance phenotype were highly resistant to TC (MIC higher than 32 mg/L), while only 3.3% of M phenotype strains was resistant to TC. CONCLUSIONS: Almost all S. pyogenes isolated in the Jinju area were susceptible to penicillin, ampi-cillin, ofloxacin, levofloxacin and chloramphenicol, but resistance rates of S. pyogenes to EM, CC and TC were relatively high. This study showed that the EM phenotypes are associated with resistance to TC.
Agar ; Ampicillin ; Anti-Infective Agents ; Child ; Chloramphenicol ; Clindamycin ; Diffusion ; Erythromycin ; Gyeongsangnam-do ; Humans ; Korea ; Levofloxacin ; Ofloxacin ; Penicillins ; Pharyngitis ; Phenotype* ; Streptococcus pyogenes* ; Tetracycline Resistance ; Tetracycline*

OBJECTIVES: The aim of this study was to determine the prevalence of asymptomatic carriers of group A β-hemolytic streptococci (GAS) in children living in a rural community and to investigate the association between episodes of acute pharyngitis and carrier status. METHODS: Throat swabs were collected from September to November 2013 among children 5-13 years of age from a rural community (Maria Ignacia-Vela, Argentina). The phenotypic characterization of isolates was performed by conventional tests. Antimicrobial susceptibility was assayed for penicillin, tetracycline, chloramphenicol, erythromycin, and clindamycin (disk diffusion). The minimum inhibitory concentration was determined for penicillin, cefotaxime, tetracycline, and erythromycin. RESULTS: The carriage of β-hemolytic streptococci was detected in 18.1% of participants, with Streptococcus pyogenes in 18 participants followed by S. dysgalactiae ssp. equisimilis in 5. The highest proportion of GAS was found in 8 to 10-year-old children. No significant association between the number of episodes of acute pharyngitis suffered in the last year and the carrier state was detected (p>0.05). Tetracycline resistance (55.5%) and macrolide-resistant phenotypes (11.1%) were observed. Resistance to penicillin, cefotaxime, or chloramphenicol was not expressed in any streptococcal isolate. CONCLUSIONS: The present study demonstrated significant throat carriage of GAS and the presence of group C streptococci (S. dysgalactiae ssp. equisimilis) in an Argentinian rural population. These results point out the need for continuous surveillance of GAS and non-GAS carriage as well as of antimicrobial resistance in highly susceptible populations, such as school-aged rural children. An extended surveillance program including school-aged children from different cities should be considered to estimate the prevalence of GAS carriage in Argentina.
Argentina* ; Carrier State ; Cefotaxime ; Child* ; Chloramphenicol ; Clindamycin ; Erythromycin ; Humans ; Microbial Sensitivity Tests ; Penicillins ; Pharyngitis ; Pharynx* ; Phenotype ; Prevalence ; Rural Population ; Streptococcus pyogenes* ; Streptococcus* ; Tetracycline ; Tetracycline Resistance

Nowadays antibiotic resistance is a worldwide serious problem that mainly affects public health. Omadacycline is a unique antibiotic which has two available dosage forms such as intravenous (IV) and oral that development for community-acquired bacterial infectious disease treatment. It is a modified form of older tetracycline at C-9 aminomethyl substituent of 6-member core ring of tetracycline. Modification form shows its activity against efflux pump and ribosomal protein protection mechanism of tetracycline resistance. Generally, omadacycline is effective against methicillin-resistant S. aureus (MRSA), Streptococcus pneumoniae, vancomycin-resistant Enterococcus (VRE), Legionella and Chlamydia spp. Efficacy, safety and tolerability profile of omadacycline those compares with recent antibiotics shows that omadacycline is less resistant than others. One derivative from tetracycline derivatives is 9-neopentylaminomethylminocycline called omadacycline was discovered and ongoing phase III clinical experiments as a therapy for acute bacterial skin and skin structure infections (ABSSSI) as well as community-acquired bacterial pneumonia (CABP). Omadacycline seems to be a strong drug candidate for future promising new antibacterial agent that is effective against ABSSSI and CABP.
Anti-Bacterial Agents* ; Bacterial Infections* ; Chlamydia ; Communicable Diseases ; Dosage Forms ; Drug Resistance, Microbial ; Enterococcus ; Legionella ; Magic* ; Methicillin Resistance ; Pneumonia, Bacterial ; Public Health ; Ribosomal Proteins ; Skin ; Streptococcus pneumoniae ; Tetracycline ; Tetracycline Resistance