• The Journal of the Korean Society for Microbiology
• /
• v.22 no.2
• /
• pp.155-162
• /
• 1987

To determine the prevalence of antibiotic resistance in fecal E. coli and to investigate possible associations between antibiotic resistance and other plasmid-mediated virulence properties, antibiotic disk susceptibility tests for nine antibiotics were done on 141 strains of E. coli isolated from diarrheal children and well controls. Eighty two percent of the test strains were resistant to one or more antibiotics. Antibiotics to which the test strains were most resistant in descending order were ampicillin (85%), trimethoprim/sulfamethoxazol (60%), and cephalothin (55%). Seventy nine percent of these resistant strains were resistant to two or more antibiotics. All 141 test strains were sorted into enterotoxigenic E. coli (ETEC), enteropathogenic E. coli (EPEC), enteroadherent E. coli (EAEC) and non-pathogenic E. coli and the percentages of strains resistant to multiple antibiotics were compared. Among ETEC regardless of its source, multiple drug resistance was more frequent in strains producing heatstable enterotoxin (ST) only than in strains producing only heat-labile enterotoxin (LT) or both. In EAEC, multiple resistance was more frequently associated with strains isolated from diarrheal patients than with those from well controls. The major antibiotic resistance patterns possessed by multiple resistant enteropathogenic strains were $SXT^R$ $AM^R$, $CR^R$, and $SXT^R$ $AM^R$ $CR^R$. Of 28 ST- producing $SXT^R$ ETEC, 26(96%) were also resistant to ampicillin and 17 (61%) were resistant to cephalothin. The similar pattern was observed in EAEC and EPEC as well. This study has important implications for the treatment of E. coli diarrhea with antibiotics because it is possible that dissemination of virulence could occur under the force of selective antibiotic pressure. In addition, this study suggests that the in vivo efficacy of SXT in treating diarrheal illness be reevaluated.

• Restorative Dentistry and Endodontics
• /
• v.39 no.4
• /
• pp.288-295
• /
• 2014

Objectives: This study was designed to evaluate the synergistic antibacterial effect of xylitol and ursolic acid (UA) against oral biofilms in vitro. Materials and Methods: S. mutans UA 159 (wild type), S. mutans KCOM 1207, KCOM 1128 and S. sobrinus ATCC 33478 were used. The susceptibility of S. mutans to UA and xylitol was evaluated using a broth microdilution method. Based on the results, combined susceptibility was evaluated using optimal inhibitory combinations (OIC), optimal bactericidal combinations (OBC), and fractional inhibitory concentrations (FIC). The anti-biofilm activity of xylitol and UA on Streptococcus spp. was evaluated by growing cells in 24-well polystyrene microtiter plates for the biofilm assay. Significant mean differences among experimental groups were determined by Fisher's Least Significant Difference (p < 0.05). Results: The synergistic interactions between xylitol and UA were observed against all tested strains, showing the FICs < 1. The combined treatment of xylitol and UA inhibited the biofilm formation significantly and also prevented pH decline to critical value of 5.5 effectively. The biofilm disassembly was substantially influenced by different age of biofilm when exposed to the combined treatment of xylitol and UA. Comparing to the single strain, relatively higher concentration of xylitol and UA was needed for inhibiting and disassembling biofilm formed by a mixed culture of S. mutans 159 and S. sobrinus 33478. Conclusions: This study demonstrated that xylitol and UA, synergistic inhibitors, can be a potential agent for enhancing the antimicrobial and anti-biofilm efficacy against S. mutans and S. sobrinus in the oral environment.

• Journal of Microbiology and Biotechnology
• /
• v.34 no.10
• /
• pp.1981-1987
• /
• 2024

This study was planned to determine the colistin-resistant (CR) gene distribution among two species of gram-negative bacteria, Pseudomonas aeruginosa and Klebsiella pneumoniae. In total, 50 isolates of K. pneumoniae (14 isolates, 28%) and P. aeruginosa (36 isolates, 72%) were isolated between August 2023 and October 2023 from clinical wound samples at Jinnah Hospital and Lahore General Hospital Lahore, Pakistan. To determine the resistance genes linked to CR and assess antimicrobial susceptibility, all isolates were kept at -80℃ in 15% glycerol broth. Using the right primer sets, a polymerase chain reaction (PCR) was utilized to identify the CR-associated mcr-1 gene of the gram-negative isolates. Out of 50, 40 isolates (80%) showed resistance against colistin with MICs of 8 and 128 ㎍/ml. The majority (97%) of P. aeruginosa CR strains were considered multidrug resistant (MDR). All K. pneumoniae isolates were resistant to cefepime, cotrimoxazole, ceftriaxone, and imipenem. The clinical CR isolates of P. aeruginosa were highly resistant to ceftriaxone, imipenem, cefepime, cotrimoxazole, ciprofloxacin, amikacin, and piperacillin/tazobactum. The antibiotic resistance pattern was terrifyingly high among both bacterial species. According to the PCR results, CR was prevalent among the gram-negative samples, and the mcr-1 gene was positive in 6/40 (15%) of the CR isolates, including four P. aeruginosa and two K. pneumoniae strains. The high CR (80%) reported in this research is cause for concern and underscores an urgent need to use colistin in a limited and logical manner, similar to other antibiotics.

• Journal of Oral Medicine and Pain
• /
• v.32 no.2
• /
• pp.137-150
• /
• 2007

Trees emit phytoncide into atmosphere to protect them from predation. Phytoncide from different trees has its own unique fragrance that is referred to as forest bath. Phytoncide, which is essential oil of trees, has microbicidal, insecticidal, acaricidal, and deodorizing effect. The present study was performed to examine the effect of phytoncide on Porphyromonas gingivalis, which is one of the most important causative agents of periodontitis and halitosis. P. gingivalis 2561 was incubated with or without phytoncide extracted from Hinoki (Chamaecyparis obtusa Sieb. et Zucc.; Japanese cypress) and then changes were observed in its cell viability, antibiotic sensitivity, morphology, and biochemical/molecular biological pattern. The results were as follows: 1. The phytoncide appeared to have a strong antibacterial effect on P. gingivalis. MIC of phytoncide for the bacterium was determined to be 0.008%. The antibacterial effect was attributed to bactericidal activity against P. gingivalis. It almost completely suppressed the bacterial cell viability (>99.9%) at the concentration of 0.01%, which is the MBC for the bacterium. 2. The phytoncide failed to enhance the bacterial susceptibility to ampicillin, cefotaxime, penicillin, and tetracycline but did increase the susceptibility to amoxicillin. 3. Numbers of electron dense granules, ghost cell, and vesicles increased with increasing concentration of the phytoncide, 4. RT-PCR analysis revealed that expression of superoxide dismutase was increased in the bacterium incubated with the phytoncide. 5. No distinct difference in protein profile between the bacterium incubated with or without the phytoncide was observed as determined by SDS-PAGE and immunoblot. Overall results suggest that the phytoncide is a strong antibacterial agent that has a bactericidal action against P. gingivalis. The phytoncide does not seem to affect much the profile of the major outer membrane proteins but interferes with antioxidant activity of the bacterium. Along with this, yet unknown mechanism may cause changes in cell morphology and eventually cell death.

• Journal of Yeungnam Medical Science
• /
• v.8 no.1
• /
• pp.53-62
• /
• 1991

Experiments were performed in mice(Balb/C) to support the basic efficacy of the human immunoglobulin (IgG) preparation. The antibacterial activity of IgG purified from human sera was examined with or without the quinolone agent, ciprofloxacin(CPFX), against Pseudomonas aeruginosa isolated from clinical specimens. Results were as follows: Antibacterial activities in terms of the percentage of survivors, after administration of Ps. aeruginosa into mouse intraperitoneal cavity were in the following order, single IgG group, CPFX administration after IgG pretreatment group, IgG and CPFX combined administration group and CPFX alone group. The number of living bacteria was monitored in blood and liver tissue of mice infected with Ps. aeriginosa and treated by IgG administration. The increase of living bacteria in liver was more drastic than that in blood. Leukocytosis was observed in mice injected with IgG, excluding those only with ciprofloxacin, after 8 hours of administration to see a decrease to normal number of bacteria after 18 hours. No significant difference was noticed between pretreatment group and post treatment group. In vitro susceptibility test of IgG against Ps. aeruginosa, minimal inhibitory concentration(MIC) was $250{\mu}g/ml$, resistant to IgG, regardless of a combined administration with CPFX. In vitro test revealed that the IgG itself did not have anti-Ps. aeruginosa activity.

• Journal of Digital Convergence
• /
• v.12 no.10
• /
• pp.477-484
• /
• 2014

The purpose of this study is to verify the antimicrobial effect of garlic and black garlic against pathogenic bacteria. For the comparative analysis of antibacterial effects of garlic, Ampicillin $10{\mu}g$ (BBL) was used as control antibiotics. Research experiments were conducted on each of November 2013 and January 2014. Susceptibility to the antimicrobial effect was measured through Kirby-Bauer disc diffusion method and verified according to the standard proposed by the CLSI. Antimicrobial effect of fresh garlic was higher regardless of the method to extract than Ampicillin $10{\mu}g$. In contrast, the manufacturing methods of the black garlic had no effective differentiations. In antimicrobial susceptibility test, black garlic showed resistance to all of 4 strains. However, in the ethanol-extract of fermented black garlic(natural aging of 15 days.) was found the small changes of the growth-inhibition-zone against S. aureus (8 mm)and E. coli(7 mm). This study proposes a variety attempts about the extraction methods of black garlic for the possibility of food preservation.

• Journal of the Korean Chemical Society
• /
• v.58 no.3
• /
• pp.258-266
• /
• 2014

Single crystals of cobalt(II) and nickel(II) complexes of 4-nitrobenzoic acid have been successfully grown by gel diffusion technique. The grown crystals were characterized by elemental analysis, FT-IR and UV-Visible spectroscopy. The structure of the grown crystals was elucidated using single crystal X-ray diffraction studies. The title compounds $[Co(Pnba)_2(H_2O)_4]{\cdot}2H_2O$ 1 and $[Ni(Pnba)_2(H_2O)_4]{\cdot}2H_2O$ 2 where PnbaH=4-nitrobenzoic acid, crystallize in centrosymmetric triclinic space group P-1. Magnetic susceptibility measurements reveal that the compounds are paramagnetic in nature. The mechanical strength of the grown crystals was determined by Vicker's microhardness studies. The ligand (4-nitrobenzoic acid) and the complexes have been screened for their biological activity against various bacteria and fungi. The activity data show that the biological activity of the complexes is higher than that of the ligand.

• Journal of Veterinary Clinics
• /
• v.25 no.4
• /
• pp.231-235
• /
• 2008

Various kinds of antibiotic intramammary infusions are used for treatment of bovine mastitis. As antibiotic-resistant bacteria are increased, the therapeutic rate for bovine mastitis is decreased. The goal of this research is to detect significant synergic effects of combination of antibiotics with sulbactam, $\beta$-lactamase inhibitor, on methicilin-resistant Staphylococcus aureus (MRSA). We used 5 strains of MRSA isolated from bovine mastitis with clinical and subclinical signs. All of the bacteria isolated had resistance to oxacillin and showed multi-resistant patterns in the antimicrobial susceptibility tests. Minimal bactericidal concentrations of ampicillin, amoxicillin, cephalexin, ampicillin/sulbactam(2:1), amoxicillin/sulbactam (2:1), and cephalexin/sulbactam (1:1) were measured according to broth microdilution method suggested by National Committee for Clinical Laboratory Standards (NCCLS, M31-A2) to compare the synergic effects of sulbactam combination with each antibiotic alone. Ampicillin and amoxicillin showed synergic antibacterial activity to 4 and 3 respectively in 5 strains of MRSA in combination with sulbactam. This study demonstrates that ampicillin/sulbactam and amoxicillin/sulbactam can be therapeutic choices for mastitis associated with MRSA.

• International Journal of Oral Biology
• /
• v.39 no.1
• /
• pp.35-40
• /
• 2014

Halitosis is caused by consumption of certain foods or drinks and production of volatile sulfur compounds (VSCs) by periodontopathogens. VSCs-related halitosis is not easily removed using mechanical or chemical therapies such as dental floss, plaque control and mouth rinse. Lactobacillus are known to be probiotics and stimulate immune systems of human. Furthermore, L. casei ATCC 334 and L. rhamnosus GG have an effect on protection of dental caries in vitro studies. The aim of this study was to investigate effect of Lactobacillus on halitosis by Fusobacterium nucleatum- and Porphyromonas gingivalis-producing VSCs and to analyze inhibitory mechanism. The periodontopathogens were cultivated in the presence or the absence Lactobacillus, and the level of VSCs was measured by gas chromatograph. For analysis of inhibitory mechanisms, the susceptibility assay of the spent culture medium of Lactobacillus against F. nucleatum and P. gingivalis was investigated. Also, the spent culture medium of Lactobacillus and periodontopathogens were mixed, and the emission of VSCs from the spent culture medium was measured by gas chromatograph. L. casei and L. rhamnosus significantly reduced production of VSCs. L. casei and L. rhamnosus exhibited strong antibacterial activity against F. nucleatum and P. gingivalis. The spent culture medium of L. casei inhibited to emit gaseous hydrogen sulfide, methyl mercaptan and dimethyl sulfide from the spent culture medium of periodontopathogens. However, the spent medium of L. rhamnosus repressed only dimethyl sulfide. L. casei ATCC 334 may improve halitosis by growth inhibition of periodontopathogens and reduction of VSCs emission.

• The Korean Journal of Food & Health Convergence
• /
• v.6 no.5
• /
• pp.1-10
• /
• 2020

Cellulitis in broiler chickens is one of the economically important problems that facing the broiler industry due to the presence of the lesion leads to condemnation of part of /or the entire carcasses. Broiler with cellulitis lesions showed lower body weight. Cellulitis was recorded on different body regions including the head, dorsum, thighs, breast, legs, and abdomen. Cellulitis results from the invasion of subcutaneous (s.c.) tissues by bacteria through disruption of skin integrity. Lesions revealed the existence of the characteristic s.c colored exudate varies from yellowish to green, which were either serosanguineous, fibrinous s.c exudate yellowish, greenish or suppurative. Many bacterial isolates including E. coli, Staphylococci, Clostridia, Aeromonas spp., Enterobacter spp., Proteus mirabilis, P. aeruginosa, and Streptococci were isolated from the lesion. Chickens exposed to immunosuppression proved to have a greater probability of developing cellulitis. The condition was experimentally induced by s.c inoculation of 25-day-old broiler chickens with E. coli, S. aureus and clostridia. Usually, bacterial isolates were multidrug-resistant. The usage of Bifidobacterium bifidum or antibiotic with avoiding immunosuppression can reduce lesion and condemnation rate resulted from cellulitis. The objective of this review is to collect different literature written about cellulitis to be available to students, researchers, and veterinarians in poultry practical.