G. Blandino

Minimal inhibitory concentrations and time-kill determination of moxifloxacin against aerobic and anaerobic isolates.

Moxifloxacin is a new oral 8-methoxy-quinolone with a wide spectrum of activity against Gram-negative and anaerobic bacteria, atypical micro-organisms and multi-resistant Gram-positive bacteria. This study was designed to assess the in vitro activity of moxifloxacin against Gram-positive bacteria with different resistance patterns, anaerobes and atypical micro-organisms such as Chlamydia and Mycoplasma. Moxifloxacin had good activity against Streptococcus pneumoniae with all strains inhibited by < or =0.12 mg/l. The minimal inhibitory concentrations (MICs) of moxifloxacin for Streptococcus pyogenes and Streptococcus agalactiae ranged from 0.03 to 0.5 mg/l while those of ciprofloxacin were about two- to four-fold higher (MICs=0.12-1 mg/l). Moxifloxacin was poorly active against enterococci but its activity against Clostridium and Bacteroides spp. was in the same range as that of metronidazole and superior to that of clindamycin. Moxifloxacin was substantially more active than both ciprofloxacin and sparfloxacin against Chlamydia.

In vitro susceptibility of Arcobacter butzleri and Arcobacter cryaerophilus to different antimicrobial agents.

Seventeen strains of Arcobacter butzleri and thirteen of Arcobacter cryaerophilus, were tested for their antimicrobial susceptibility to 26 antimicrobial agents. Among beta-lactams agents in this study, imipenem was the most active agent against both A. butzleri and A. cryaerophilus isolates with MIC(90) values of 2 and 4 mg/l, respectively. The most active cephalosporin tested was cefepime, although it was more active against A. butzleri (MIC(90) 8 mg/l) than A. cryaerophilus (MIC(90) 64 mg/l). Levofloxacin, marbofloxacin, enrofloxacin and ciprofloxacin were the best-performing fluoroquinolones against these species. Of the aminoglycosides, amikacin was the most active agent against both A. butzleri and A. cryaerophilus strains with MIC(90) values of 64 and 16 mg/l, respectively. All isolates showed high levels of resistance to penicillins, macrolides, chloramphenicol, trimethoprim and vancomycin.

Antibacterial activity of moxifloxacin against periodontal anaerobic pathogens involved in systemic infections

The in vitro activity of moxifloxacin was compared with that of penicillin G, amoxycillin/clavulanate, cefoxitin, erythromycin, clindamycin and metronidazole against 158 isolates associated with periodontal infections. MIC(50)/MIC(90) values of moxifloxacin were respectively 0.06/0.5 mg/l for Porphyromonas gingivalis (35), for Prevotella spp. (28) and Actinomyces spp. (35), 0.12/0.25 mg/l for Fusobacterium nucleatum (20) and 0.06/0.12 mg/l for Peptostreptococcus spp. (30). The minimum inhibitory concentration (MIC) range of moxifloxacin for Bacteroides forsythus (6) and Campylobacter rectus (4) was 0.06-0.12 mg/l. The minimum bactericidal concentrations were equal to or 2-4 times the MIC values. Moxifloxacin produced a bactericidal effect at 8 h. Our results show that moxifloxacin has good antibacterial activity against periodontal pathogens comparable with that of cefoxitin and amoxycillin/clavulanate, and better than that of clindamycin, metronidazole and penicillin.

Bacteriological findings and antimicrobial resistance in odontogenic and non-odontogenic chronic maxillary sinusitis.

The main objectives of this study were to estimate the frequency of chronic maxillary sinusitis of dental origin, and to evaluate the microbiology of odontogenic and non-odontogenic chronic maxillary sinusitis. Aspirates from 59 patients with chronic maxillary sinusitis (47 non-odontogenic, 12 odontogenic), collected during a 3-year period, were microbiologically processed for aerobic and anaerobic bacteria. Moreover, antimicrobial susceptibility was evaluated in the isolated bacteria. In this study, 20 % of chronic maxillary sinusitis cases were associated with a dental origin, and sinus lift procedures were the main aetiological factor. Our microbiological findings showed that all specimens from chronic maxillary sinusitis were polymicrobial. Sixty aerobes and 75 anaerobes were recovered from the 47 cases of non-odontogenic sinusitis (2.9 bacteria per specimen); 15 aerobes and 25 anaerobes were isolated from the 12 patients with odontogenic sinusitis (3.3 bacteria per specimen). The predominant aerobes were Staphylococcus aureus (27) and Streptococcus pneumoniae (16), while the more frequent anaerobes were Peptostreptococcus species (31) and Prevotella species (30). Haemophilus influenzae and Moraxella catarrhalis were absent in sinusitis associated with a dental origin. Overall, 22 % of Staphylococcus aureus isolates were oxacillin-resistant, and 75 % of Streptococcus pneumoniae isolates were penicillin-resistant and/or erythromycin-resistant; 21 % of anaerobic Gram-positive bacteria were penicillin-resistant, and 44 % of anaerobic Gram-negative bacteria were β-lactamase-positive. Vancomycin and quinopristin-dalfopristin had the highest in vitro activity against Staphylococcus aureus and Streptococcus species, respectively; amoxicillin-clavulanate and cefotaxime showed the highest in vitro activity against aerobic Gram-negative bacteria; and moxifloxacin, metronidazole and clindamycin were the most active against anaerobic bacteria.

Effect of a broad-spectrum cephalosporin on the oral and intestinal microflora in patients undergoing colorectal surgery.

The influence of ceftriaxone on oral and intestinal flora was investigated in 10 patients undergoing colorectal surgery. Ceftriaxone was given intravenously in one 2g dose before anesthesia. Saliva and feces samples were collected and analyzed on day 0, 3, 5, 14 and 28 after drug administration. All specimens were cultured quantitatively for aerobic and anaerobic microorganisms; representative colonies of each morphologic type of organism cultured were identified. The oral aerobic flora was somewhat affected by the administration of ceftriaxone. In all patients the number of Streptococci, Staphylococci and Neisseria decreased during the 5 days after ceftriaxone administration. No significant changes in the number of anaerobic commensal occurred. The oral microflora of all patients after 14 days had returned to normal. The aerobic fecal flora was considerably affected: in all patients enterobacteria were eliminated or strongly suppressed. Only minor changes in the number of aerobic gram-positive bacteria were observed, and the anaerobic intestinal flora showed only minor alterations. On day 28 the intestinal flora were normalized in all respects. No new colonizing microorganisms were isolated during the investigation period and no colonization with ceftriaxone-resistant bacteria was observed. No postoperative infection occurred and no adverse effects were registered.

Antimicrobial Susceptibility and β-Lactamase Production of Anaerobic and Aerobic Bacteria Isolated from Pus Specimens from Orofacial Infections

Abstract 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 β-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.

Probiotics: overview of microbiological and immunological characteristics

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.

The Italian Epidemiological Survey 1997 /1999 Antimicrobial susceptibility data of Haemophilus influenzae, Haemophilus parainfluenzae and Moraxella catarrhalis in Italy

The Italian Epidemiological Survey began a surveillance study with the aim of monitoring the antimicrobial resistance of respiratory pathogens. From 1997 to 1999, 2028 strains of Haemophilus influenzae and 523 strains of Haemophilus parainfluenzae were collected from 59 Clinical Microbiology Laboratories distributed throughout Italy. In 1998, the study was extended to include Moraxella catarrhalis and a total of 360 isolates were collected. There was a significant increase in the beta-lactamase production both for H. influenzae (from 5% in 1997 to 16% in 1999) and for H. parainfluenzae (from 5% in 1997 to 22% in 1999). Beta-lactamase production in M. catarrhalis was 84% in 1998 and 87% in 1999. Beta-lactamase production affected the susceptibility to unprotected penicillins (87% in H. influenzae, 85% in H. parainfluenzae and 34% in M. catarrhalis), and in part the susceptibility to cefaclor (about 98%). Amoxycillin/clavulanate, cefixime, ceftriaxone and ciprofloxacin were active against all strains of H. influenzae, H. parainfluenzae and M. catarrhalis.

Chemical and biological properties of the novel exopolysaccharide produced by a probiotic strain of Bifidobacterium longum

Bifidobacterium longum W11 is a commercialized probiotic that has an exopolysaccharide (EPS) layer covering its surface which could play a role in the beneficial properties attributed to the strain; thus, we have carried out chemical and biological analyses of this polymer. The eps cluster putatively involved in the polymer synthesis presented a unique structural organization not previously reported in bifidobacteria. B. longum W11 produced a complex polysaccharide blend with the main component composed of glucose and galactose. An exhaustive structural analysis identified two different repeating units: one linear [→6)-β-Galf-(1→3)-α-Galp-(1→] and one, more abundant, with the same backbone in which the β-Galf is 5-substituted by a β-Glcp unit. The antioxidant capability and the lack of toxicity of the whole EPS W11 mixture, as well as some functional characteristics of the producing strain, such as the in vitro resistance to gastrointestinal conditions and the adhesion of colonocytes, were also determined.

Cefetamet Pivoxil: Comparable Evaluation with Other Orally Available Antibiotics against Selected Species of Respiratory Pathogens

Cefetamet pivoxil, the prodrug ester of cefetamet, is a new third-generation cephalosporin with a broad spectrum of activity. The in vitro activity of cefetamet was superior to that of cefaclor, ceftibuten, amoxicillin plus clavulanic acid, and amoxicillin alone when tested against 403 strains of freshly isolated upper and lower respiratory tract pathogens. Cefetamet killed 100% Haemophilus influenzae and H. parainfluenzae, including beta-lactamase-producing strains, at < or = 0.25 mg/l, Streptococcus pyogenes and S. pneumoniae at < or = 0.5 mg/l, S. agalactiae at < or = 0.1 mg/l, and streptococci at < or = 2.0 mg/l. Moreover, at < or = 4 mg/l (breaking point), cefetamet was also highly effective against Escherichia coli (94%), Klebsiella pneumoniae (92%), K. oxytoca (91%) and, at 1 mg/l, against Moraxella catarrhalis (90%), including beta-lactamase-producing strains. Furthermore, time-killing analyses at 4 x MIC demonstrated that cefetamet was bactericidal against beta-lactamase-producing H. influenzae, M. catarrhalis, and K. pneumoniae within 6 h and S. pneumoniae within 4 h. Hydrolysis studies confirmed cefetamets stability to TEM1 and SHV1, the most common enterobacterial beta-lactamases.