Most suppurative orofacial infections are polymicrobial. Information regarding the antimicrobial susceptibility of the microorganisms involved can be useful in the choice of an effective antibiotic therapy. In this study we determined the antimicrobial susceptibility of a total 235 anaerobic and aerobic bacteria recently isolated from pus specimens of orofacial infections. All the viridans streptococci were susceptible to penicillin, cefotaxime, cefoxitin, imipenem and levofloxacin. Imipenem and levofloxacin were active against 100% of the anaerobic Gram-positive organisms isolated. Among the anaerobic Gram-negative rods beta-lactamase production was detected in all species except Campylobacter rectus. Amoxicillin-clavulanate, cefoxitin, imipenem and metronidazole were active against all the isolates of anaerobic Gram-negative species. Isolates resistant to erythromycin were found in all the species tested, however, resistance to clindamycin was only detected in Porphyromonas gingivalis and Bacteroides ureolyticus. Isolates resistant to levofloxacin were detected in P. gingivalis and Prevotella sp.

The objective of the study was to characterize at species level by phenotypic and different molecular methods the strains of Lactobacillus spp. used as constituents of five oral and four vaginal products. Susceptibilities to representative antibiotics were evaluated. In addition, total viable counts at mid and 3 months to deadline of shelf life, in the different formulations and the presence of eventual contaminant microorganisms were investigated. In all oral products the molecular characterization at species level of the strains of Lactobacillus spp. confirmed the strains stated on the label, except for one strain cited on the label as Lactobacillus casei, that our study characterized as Lactobacillus paracasei. In oral products total viable cell content complied with content claimed on the label. In three out four vaginal products (one product claimed “bacillo di Döderlein”), molecular characterization complied with the bacterial name stated on the label. Two vaginal products reported viable counts on the label that were confirmed by our study. The other vaginal products, which did not report bacterial counts on the label, showed a similar decrease of viable counts at different dates to deadline compared to the others. From all the tested products, contaminant microorganisms and acquired resistance to representative antibiotics by the probiotic strains were not detected.

Objective: An emerging issue of probiotic products is the antibiotic resistance of the strains used. The aim of this study was to determine the susceptibility of the isolates of 10 probiotic products available in Italy. Materials and methods: The susceptibility of 15 strains of Lactobacillus spp., 5 Streptococcus salivarius ssp. thermophilus, 1 Enterococcus faecium and 8 Bifidobacterium spp. to several groups of antibacterial agents was determined by E-test using MRS agar for Lactobacillus spp. and E. faecium and MH agar'5% sheep blood for S. thermophilus, with different conditions of incubation. For Lactobacillus, S. thermophilus and E. faecium the MICs obtained by E-test were compared to the MICs by broth microdilution test obtained following CLSI M45-A (2006) and CLSI M100-S17 (2007) guidelines. Results: The broth microdilution test resulted in MICs identical to those obtained with the E-test or in MICs with differences of 1 or 2 log dilution steps. All the strains of Lactobacillus were susceptible to ampicillin. Species-dependent antibiotic susceptibility was detected for cephalosporins; gentamicin and ciprofloxacin had variable activity. Intrinsic resistance to vancomycin was confirmed for L. paracasei, L. salivarius and L. plantarum. Atypical resistance to erythromycin was detected in one strain of L. salivarius. The strains of Bifidobacterium were susceptible to ampicillin, cefotaxime and erythromycin. The strains of E. faecium were susceptible to the tested antibiotics; the strain of S. thermophilus was resistant only to ciprofloxacin. The observed resistance in the strains used in the Italian probiotic products tested seemed to be intrinsic except for erythromycin in one L. salivarius strain.

Over the last few years, probiotics (commercialized as food, dietary supplements of living bacteria or pharmaceuticals) have attracted the interest of scientists as well as consumers. Recent public interest in healthier lifestyles, together with the acceptance by physicians of nonmainstream therapies, has refocused attention on the role of human microbiota in the prevention and therapy of diseases. Modulation of the intestinal microbiota may be achieved by consuming living bacteria or by consuming a combination of probiotics and prebiotics. In addition, we are learning more about the biology of probiotic microorganisms, through sequencing their genomes, and the interactions of probiotics with human cells and with pathogenic bacteria. Results from well-conducted clinical studies help to increase the acceptance of probiotics for the treatment and prevention of selected diseases, both inside and outside the GI tract. Moreover, the use of selected probiotics for particular subject groups may provide more specific health effects. The medical profession is in an ideal position to guide the consumer towards appropriate prophylactic or therapeutic uses of probiotics in health or in specific disease states.

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