ABSTRACT
Bacterial infections are a prevalent complication after primary viral respiratory infections and are associated with high morbidity and mortality. Antibiotics are widely used against bacterial respiratory pathogens; however, the rise in antibiotic-resistant strains urges us to search for new antimicrobial compounds, including ones that act synergistically with antibiotics. In this study, the minimal inhibitory (MIC) and minimal bactericidal (MBC) concentrations of a polyphenol-rich complex of green propolis, Tabebuia avellanedae bark, and Olea europaea leaf extracts against Staphylococcus aureus, Haemophilus influenzae, and Klebsiella pneumoniae were determined, followed by an analysis of the synergistic effect with clarithromycin, azithromycin, and amoxiclav (875/125 mg amoxicillin/clavulanic acid). A combination of extracts showed activity against all three bacterial strains, with MIC values ranging from 0.78 to 12.5 mg/mL and MBC values from 1.56 to 12.5 mg/mL. The extracts showed synergistic activity with azithromycin and clarithromycin against S. aureus, with clarithromycin against K. pneumoniae, and with all three tested antibiotics against H. influenzae. Synergy with clarithromycin was additionally evaluated in a time-kill assay where the synergistic effects against S. aureus and K. pneumoniae were seen within the first 6 h of incubation. The results show the potential of polyphenol-rich extracts in enhancing the efficacy of antibiotic therapy and indicate their potential to be used in the management of respiratory infections.
ABSTRACT
OBJECTIVE: The aim of the present study was to investigate the microbial flora of root filled teeth with apical periodontitis and to determine the prevalence of ß-lactamase producing strains in isolated bacteria in Latvian patients. MATERIALS AND METHODS: 33 root filled teeth with asymptomatic persisting periapical lesions were selected for the present study. During nonsurgical endodontic retreatment, the root filling material was removed and canals were sampled. Determination of microbial species was based on series of biochemical tests using identification kits. All strains of bacteria were tested for ß-lactamase production by using chromogenic nitrocefin-impregnated slides. RESULTS: Bacteria were found in 32 (97%) of initial specimens from the teeth. The number of isolated microbial strains in the specimens ranged from one to six (mean 2.7). 79% of the isolated microbial species were Gram-positive bacteria. The most common isolates were Streptococcus (27%), Actinomyces (27%), Staphylococcus (18%), Enterococcus (18%) and Lactobacillus (18%) spp. Yeasts were found as four isolates in 3 cases (9%). ß-lactamase-producing bacterial strains were detected in 12 specimens, 36% of the patients. The most common enzyme-producing bacteria belonged to Actinomyces and Staphylococcus spp. CONCLUSIONS: The microbial flora in previously treated root canals with apical periodontitis is limited to a small number of predominantly Gram-positive microbial species. The most common isolates are Streptococcus, Actinomyces, Staphylococcus, Enterococcus and Lactobacillus spp. A moderately high prevalence of ß-lactamase producing bacterial strains was detected in patients with root filled teeth with apical periodontitis.
