Academic literature on the topic 'MDR Streptococcus mitis'

Dental caries is an infectious oral disease caused by the presence of different bacteria in biofilms. Multidrug resistance (MDR) is a major challenge of dental caries treatment. Swabs were taken from 65 patients with dental caries in Makkah, Saudi Arabia. Swabs were cultivated on mitis salivarius agar and de Man, Rogosa, and Sharpe (MRS) agar. VITEK 2 was used for the identification of isolated bacteria. Antibiotic susceptibility testing of the isolated bacteria was performed using commercial antibiotic disks. Ulva lactuca was used as a reducing agent and cellulose source to create nanocellulose and Ag/cellulose nanocomposites. Fourier-transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray diffraction spectroscopy (XRD) were used to characterize nanocellulose and Ag/cellulose nanocomposites. The results showed that most bacterial isolates were Streptococcus spp., followed by Staphylococcus spp. on mitis salivarius media. Lactobacillus spp. and Corynebacterium group f-1 were the bacterial isolates on de Man, Rogosa, and Sharpe (MRS) media. The antibiotic susceptibility test revealed resistance rates of 77%, 93%, 0, 83%, 79%, and 79% against penicillin G, Augmentin, metronidazole, ampicillin, ciprofloxacin, and cotrimoxazole, respectively. Ag/cellulose nanocomposites and Ag/cellulose nanocomposites with fluoride were the most effective antibacterial agents. The aim of this work was to assess the antibacterial activity of Ag/cellulose nanocomposites with and without fluoride against bacteria isolated from the oral cavities of patients with dental caries. This study demonstrated that Ag/cellulose nanocomposites have antibacterial properties against multidrug-resistant bacteria that cause dental caries.

Upper respiratory tract infection and pneumonia in foals are primarily caused by a bacterial infection. Gram-negative bacteria are commonly found in neonatal pneumonia although gram-positive and mixed infections could be accompanied. The current study aimed to detect the different pathogens causing respiratory disorders in the equine, describe the antimicrobial resistance in these pathogens, and determine the types of antimicrobial isolates. A total of 203 different samples were collected from 42 horse foals, 5 adult horses, and 4 donkey foals from June 2019 to April 2020. All samples were subjected to bacteriology analysis and isolated bacteria were analyzed using susceptibility test for different antibacterial agents. The findings indicated that 38 (74.5%) animals were positive for the isolation of bacteria causing respiratory disorders. The most predominant isolates were Klebsiella pneumoniae subsp. Pneumoniae followed by Staphylococcus aureus, Streptococcus equi, Pseudomonas aeruginosa, Streptococcus zooepidemicus, Proteus mirabilis, Rhodococcus equi, Stenotrophomonas maltophilia, and Streptococcus mitis. Stenotrophomonas maltophilia is isolated from all organs, including the lungs. All K. pneumoniae isolates were sensitive to lomefloxacin, cefotaxime, meropenem, enrofloxacin, neomycin, and chloramphenicol. The Pseudomonas aerugenosa (P. aeruginosa) is sensitive to aztreonam and 20% of isolates sensitive to Piperacillin-tazobactam. All Proteus mirabilis were sensitive to ampicillin-sulbactam, piperacillin-tazobactam, and cefoperazone. Stenotrophomonas maltophilia was only sensitive to oxytetracycline and lomefloxacin. Staphylococcus aureus was susceptible to Piperacillin-tazobactam (50%), 25% to lomefloxacin; Streptococcus equi were sensitive to vancomycin 33.3% while 16.7% to erythromycin and doxycycline, Streptococcus zooepidemicus (100%) were sensitive to cefotaxime, meropenem, and doxycycline. All isolates of Enterococcus species were sensitive to penicillin, piperacillin-tazobactam, and lomefloxacin. Moreover, Rhodococcus equi (one isolate) was only sensitive to clarithromycin. The antimicrobial susceptibility test illustrated the presence of multidrug-resistant and pan-drug resistant isolates which proved the indiscriminate and extensive use of antibiotics. In conclusion, resistance monitoring data and risk assessment identified several direct and/or indirect predisposing factors to be potentially associated with MDR development in the equine health sector of Egypt. The predisposing factors may be attributed to insufficient veterinary healthcare, monitoring, and regulatory services, in addition to the intervention of animal health service providers, and/ or farmers’ lack of knowledge about drugs. The misuse and overuse of antibiotics have led to the evolution of antibiotic-resistant bacteria in equine in Egypt.

Background: Many bacterial infections including dental caries that caused by Streptococcus mutans (S. mutans) were difficult to be treated due to the unavailability of effective antibiotics. Therefore, it requires to focus the attention on endolysin as an antibacterial agent. This study was designed to evaluate the In-vitro effectiveness of specific bacteriophage endolysins against S. mutans isolated from dental caries.Methods: Twenty-five isolates of S. mutans were collected from patients with dental caries attended to Al-Imamain Al-Kadhimain, Medical City Hospital, and AL-Ameen Health Center, during the period from December 2021 to May 2022. The S. mutans isolates were identified by culturing them on their specific mitis salivarius sucrose bacitracin tellurite media (MS-SBT agar), morphological characteristics, gram staining, biochemical tests and VITEK 2 compact system. Seven of these S. mutans isolates were used for the in-vitro study.Results: The bacteriophage endolysin enzyme extracted from the corresponding S. mutans isolate was effective as In-vitro antibacterial agent with minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) ranging between (13.63 – 17.83) µg/ml and (17.04-22.28) µg/ml respectively.Conclusion: The endolysin was effective as antibacterial agent against multi-drug resistant (MDR) S. mutans upon growing and testing on culture media.

Abstract Background Fluoroquinolones have been used for infection prevention in patients with cancer (PWC). They are active against many Gram-negative bacilli (GNB) but are less active against Gram-positive organisms (GPO). Quinolone resistance is increasing and many institutions are using combination regimens for antimicrobial prophylaxis. We evaluated the in vitro activity of delafloxacin (DLX), a novel fluoroquinolone, and selected comparators against 560 bacterial isolates from PWC. Methods Isolates were from recent blood cultures. Susceptibility testing and time kill studies (TKS) were performed using CLSI approved methodology. Appropriate ATCC control strains were used. We calculated MIC50, MIC90, MIC ranges and percent susceptibility using FDA breakpoints when available. TKS were performed on 4 streptococcus mitis isolates at concentrations of MIC, 4x MIC, and 8x MIC. Results DLX was more active than ciprofloxacin (CIP) and levofloxacin (LEV) against methicillin-susceptible (MSSA), and resistant (MRSA) S. aureus, coagulase-negative staphylococci (CoNS), and viridans group streptococci (VGS), and had similar activity against beta-hemolytic streptococci. It also had low MICs for Bacillus species (SPP.), Listeria monocytogenes, Micrococcus spp., and Rothia spp. Overall GPO susceptibility was 73% to DLX, 42% to CIP, and 52% to LEV. The activity of DLX against Enterobacterales was similar to CIP and LEV. All 3 agents had moderate activity against Citrobacter spp., and non-MDR P. aeruginosa. Notably, all 3 quinolones had poor activity against E. coli, P. mirabilis, and MDR P. aeruginosa, all common pathogens in PWC. All 3 had low MICs for Acinetobacter spp. DLX and LEV achieved peak bactericidal activity at 6-8 h against all 4 VGS isolates (maximum activity at 8x MIC) but this was not always sustained at 24 h. Table 1. Percent Susceptibility of selected Gram-positive isolates to Delafloxacin, Ciprofloxacin and Levofloxacin Table 2. Percent Susceptibility of selected Gram-negative isolates to Delafloxacin, Ciprofloxacin and Levofloxacin Figure 1. Bactericidal Activity of DLX at 1x , 4x, and 8x MIC against VGS - Time Kill Study Conclusion DLX is more active than CIP and LEV against many GPO from PWC (including S. aureus and VGS), but like these agents there are significant gaps in its coverage against GNB. It is probably not suitable as a single agent for antimicrobial prophylaxis in high-risk PWC. The current practice of combining a quinolone with a beta-lactam probably still represents the best option in PWC who need prophylaxis. Disclosures Kenneth Rolston, MD, Tetraphase Pharmaceuticals (Grant/Research Support)