[Antimicrobial susceptibility of clinical isolates of aerobic Gram-positive cocci and anaerobic bacteria in 2006].

The activity of antibacterial agents against aerobic Gram-positive cocci (26 species, 1022 strains) and anaerobic bacteria (23 species, 184 strains) isolated from clinical specimens in 2006 at 16 clinical facilities in Japan were studied using either broth microdilution or agar dilution method. The ratio of methicillin-resistant strains among Staphylococcus aureus and Staphylococcus epidermidis was 53.0% and 65.8%, suggesting that resistant strains were isolated at high frequency. Vancomycin (VCM) and quinupristin/dalfopristin (QPR/DPR) had good antibacterial activity against methicillin-resistant S. aureus and methicillin-resistant S. epidermidis, with MIC90s of < or = 2 micrcog/mL. The ratio of penicillin (PC) intermediate and resistant strains classified by mutations of PC-binding proteins among Streptococcus pneumoniae was 87.6%. Ceftriaxone, cefpirome, cefepime, carbapenem antibiotics, VCM, teicoplanin, linezolid(LZD) and QPR/DPR had MIC90s of < or = 1 microg/mL against PC-intermediate and resistant S. pneumoniae strains. Against all strains of Enterococcus faecalis and Enterococcus faecium, the MICs of VCM and TEIC were under 2 microg/mL, and no resistant strain was detected, suggesting that these agents had excellent activities against these species. 10.9% of E. faecalis strains or 3.5% of E. faecium strains showed intermediate or resistant to LZD. 24.4% of E. faecium strains showed intermediate or resistant to QPR/DPR. Against all strains of Clostridium difficile, the MIC of VCM were under 1 microg/mL, suggesting that VCM had excellent activity against C. difficile. Carbapenems showed good activity against Peptococcaceae, Bacteroides spp., and Prevotella spp. However since several strains of Bacteroides fragilis showed resistant to carbapenems and the susceptibility of this species should be well-focused in the future.

An in vitro study of the antimicrobial activity of some endodontic medicaments and their bases using an agar well diffusion assay.

BACKGROUND: The aim of this study was to determine the in vitro antimicrobial activities of various endodontic medicaments and their bases against selected organisms using an agar diffusion assay. METHODS: An agar well diffusion assay was used to test the antimicrobial action of some commonly used endodontic medicaments (Ledermix paste, Pulpdent paste, Ultracal paste, and a 50:50 mix of Ledermix and Pulpdent pastes) and their bases. Three bacterial species (E. faecalis, P. micros, P. intermedia) and one yeast (C. albicans) were selected. The diameters of growth inhibition zones and pH were assessed. RESULTS: P. micros demonstrated the highest level of in vitro resistance. Pulpdent and Ultracal pastes had the highest pH (12.64 and 12.53, respectively). The addition of Pulpdent to Ledermix did not increase the zone sizes significantly. CONCLUSIONS: All the commercial products showed some in vitro antimicrobial activity. Ledermix paste and the 50:50 Ledermix/Pulpdent mixture being the most effective in this model. The known anti-inflammatory/analgesic properties of Ledermix and the results from this agar model suggest that the 50:50 Ledermix/Pulpdent combination would be the preferred medicament for clinical use in symptomatic cases, even though the addition of calcium hydroxide to Ledermix did not appear to be synergistic in terms of enhancing the antimicrobial action.

Gut Dysbiosis and Neurobehavioral Alterations in Rats Exposed to Silver Nanoparticles.

Due to their antimicrobial properties, silver nanoparticles (AgNPs) are being used in non-edible and edible consumer products. It is not clear though if exposure to these chemicals can exert toxic effects on the host and gut microbiome. Conflicting studies have been reported on whether AgNPs result in gut dysbiosis and other changes within the host. We sought to examine whether exposure of Sprague-Dawley male rats for two weeks to different shapes of AgNPs, cube (AgNC) and sphere (AgNS) affects gut microbiota, select behaviors, and induces histopathological changes in the gastrointestinal system and brain. In the elevated plus maze (EPM), AgNS-exposed rats showed greater number of entries into closed arms and center compared to controls and those exposed to AgNC. AgNS and AgNC treated groups had select reductions in gut microbiota relative to controls. Clostridium spp., Bacteroides uniformis, Christensenellaceae, and Coprococcus eutactus were decreased in AgNC exposed group, whereas, Oscillospira spp., Dehalobacterium spp., Peptococcaeceae, Corynebacterium spp., Aggregatibacter pneumotropica were reduced in AgNS exposed group. Bacterial reductions correlated with select behavioral changes measured in the EPM. No significant histopathological changes were evident in the gastrointestinal system or brain. Findings suggest short-term exposure to AgNS or AgNC can lead to behavioral and gut microbiome changes.

Ticarcillin disodium in anaerobic infections.

Twenty-five patients were treated with ticarcillin disodium, 18 of whom had anaerobic infections that included pleuropulmonary infections (seven), mandibular osteomyelitis (four), perirectal abscess (two), sepsis, primary site unknown (one), liver abscess (one), pelvic abscess (one), decubitus ulcer (one), and synergistic gangrene (one). Seven had no anaerobic infections. Three had anaerobic septicemia. Culture results included anaerobes: peptococci (ten), peptostreptococci (ten), Bacteroides fragilis (six), Bacteroides not fragilis (ten), eubacteria (three), fusobacteria (two), Clostridium (one), Veillonella (one), and acidaminococcus (one); aerobes: Proteus (three), Klebsiella (two), Escherichia coli (two), and streptococci (two). Six patients with mixed aerobic infections initially received gentamicin sulfate in addition. The serum levels were 110 +/- 20 microgram/ml one hour after intravenous infusion of 5 g of ticarcillin disodium. All anaerobic isolates were susceptible at less than or equal to 100 microgram/ml and 85% by less than or equal to 25 microgram/ml of ticarcillin. Sixteen patients responded well to ticarcillin and two failed to respond. Our study suggests that ticarcillin is useful in the treatment of anaerobic infections.

Antimicrobial activity of antituberculosis agents against anaerobic bacteria.

Anaerobic infections may coexist with tuberculosis, and can be mistaken for one another. The effect of therapy with antituberculosis chemotherapeutic agents against anaerobic bacteria (with the exception of rifampin) is unknown. We therefore examined the in vitro efficacy of certain commonly used antituberculosis agents (rifampin, isoniazid, and ethambutol) against 370 strains of anaerobic bacteria, including 86 isolates of Bacteroides fragilis. Rifampin at a concentration of 2 microgram/ml inhibited 91 percent of all anaerobic isolates. Both ethambutol and isoniazid were totally ineffective against any of the anaerobes tested, even at 64 microgram/ml. Therapy with rifampin in an unsuspected anaerobic infection can be misdiagnosed for tuberculosis. Therefore, when tuberculosis is suspected, isoniazid and ethambutol can be used and rifampin withheld until the acid-fast bacilli are demonstrated by additional diagnostic procedures, such as transtracheal aspiration.

Novobiocin and the differentiation of peptococci and peptostreptococci.

Paper discs containing 5 microng of novobiocin were used as a presumptive test to differentiate peptococci and peptostreptococci. Zone diameters were measured and minimum inhibitory concentrations (MIC) of the antibiotic for each group were performed to ascertain the activity of the antibiotic against these genera. All strains of peptococci showed no zone of inhibition in the disc test together with an MIC of 25 microng/ml or greater. All strains of peptostreptococci showed zones of inhibition of at least 15 mm diameter together with an MIC of 1-6 microng/ml or less.

A review. Lessons from an animal model of intra-abdominal sepsis.

Intra-abdominal sepsis that involves multiple aerobic and anaerobic bacteria derived from the colonic flora was studied in Wistar rats to determine the relative roles of various microbial species. The rats challenged with pooled colonic contents showed a biphasic disease. Initially, there was acute peritonitis, Escherichia coli bacteremia, and high mortality. In rats that survived this acute peritonitis stage, intra-abdominal abscesses developed, and anaerobic bacteria were the preponderant organisms. Subsequent experiments showed that antibiotics directed against coliforms prevented mortality, whereas agents active against anaerobes reduced the incidence of abscesses. Challenges with Escherichia coli alone produced bacteremia and death, whereas pure cultures of Bacteroides fragilis caused intra-abdominal abscesses. These observations suggest that both coliforms and anaerobes are important pathogens in intra-abdominal sepsis, although the different types of microbes appear to play distinctive roles in the sequence of pathological events.

Anaerobic bacteria isolated from foot infections in diabetic patients: in vitro susceptibility to nine antibiotics.

Twenty-nine isolates of anaerobic bacteria from foot infections in diabetic patients were tested, using the agar dilution method, for in vitro susceptibility to nine antimicrobial agents. Imipenem and metronidazole showed excellent activity; clindamycin and chloramphenicol were next in terms of efficacy. Cefoxitin and moxalactam demonstrated good activity, although three isolates of the Bacteroides fragilis group were resistant to moxalactam. Penicillin G, cefotaxime, and cefoperazone showed poor activity against the B fragilis group but were quite active against other anaerobes. Among the newer beta-lactam antibiotics studied, imipenem, cefoxitin and, to a lesser extent, moxalactam appear promising for clinical use as anti-anaerobic antibiotics in the treatment of foot infections in diabetic patients.

Antibacterial effects of various endodontic medicaments on selected anaerobic bacteria.

This study was undertaken to determine the antibacterial effects of various endodontic medicaments against six selected anaerobic bacteria. The experiment involved the testing of the vapors of six medicaments using agar plates streaked with the bacteria. A zone of inhibition was recorded for each plate and the results were analyzed statistically. Formocresol produced significantly larger zones of inhibition than any of the other medicaments.

Anaerobic susceptibility tests. Evaluation of the stability of antimicrobials in Wilkens-Chalgren broth and the effect of media prereduction.

The stability of eight antimicrobial agents in WILKENS-CHALGREN broth was evaluated. The activities of only carbenicillin and benzyl penicillin were significantly decreased after storage for eight weeks at--20 degrees C. Anaerobic reduction of the susceptibility testing broth prior to inoculation was found to be unnecessary.

Susceptibility of New Zealand isolates to anaerobic bacteria to tinidazole.

Minimum inhibitory and minimum bactericidal concentrations (MIC, MBC) of tinidazole for 80 New Zealand isolates of anaerobic bacteria were determined. Growth of 95 percent of the isolates was inhibited by 4 micrograms/ml or less of tinidazole. MBC values were the same as, or one dilution higher than, the MIC.

Erythromycin and anaerobes: in vitro aspects.

Anaerobic organisms are being increasingly recognised as important causes of serious infection in man. Sampling procedures, transport of specimens and laboratory techniques need to be constantly monitored and improved if the causative organisms are to be consistently recovered from clinical specimens. Once the organisms have been isolated, their susceptibility to antibiotics should be determined so that the clinician can base his antibiotic therapy on reliable laboratory results. There are many variables in the sensitivity testing of anaerobes--these may account for the difficulty reported by some workers in obtaining consistently reliable results with some antibiotics, including erythromycin. These problems can be largely overcome if a standardised procedure is adopted. It is clear from the published data that erythromycin has considerable in vitro activity against many strains of anaerobic bacteria, both sporing and non-sporing. There is a broad spectrum of activity with some strains being very sensitive and a few strains being resistant. M.I.C. values range from 0.04 microgram./ml. to 20 microgram./ml. or more. Further studies are now needed to assess the role of erythromycin in the treatment of anaerobic infections in vivo.

[Experimental and clinical evaluation of T-1982 (cefbuperazone) in the field of obstetrics and gynecology].

Experimental and clinical studies of T-1982 (cefbuperazone), a new cephamycin antibiotic, were performed in the field of obstetrics and gynecology, and the following results were observed. T-1982 was determined for its in vitro activity against 180 recent clinical isolates in comparison with cefmetazole (CMZ) and cefazolin (CEZ). The activity of T-1982 was superior to that of CMZ against E. coli (101 strains) and B. fragilis (19 strains), and similar to that of CMZ and CEZ against Peptococcus (34 strains). High concentrations of T-1982 exceeding the MIC values against various bacteria were maintained for a few hours in the female genital organs and postoperative retroperitoneal exudate after intravenous drip infusion of 2 g. T-1982 was administered to a total of 6 patients in daily dose of 2 approximately 3 g for 2 approximately 10 days. The clinical results were excellent or good in 5 cases. Drug eruption was observed in 1 case. These results suggest that T-1982 is highly effective for the treatment of bacterial infections in this field.

The frequency and some characteristics of anaerobic bacteria isolated from various forms of bovine mastitis.

The prevalence of strictly anaerobic bacteria in the secretions from untreated cases of mastitis in lactating dairy cows was investigated. The study involved 147 Friesland cows in 12 highveld herds. All herds yielded cows with anaerobic udder infections. No anaerobic bacteria were recovered from cows with normal quarters or those with latent aerobic infections. Only anaerobes were present in 10% of so-called 'aseptic' mastitis cases. A variety of anaerobic organisms was isolated concurrently with facultative bacteria from 5,3% and 58,8% of cases classified as subclinical and clinical respectively. Peptococcus spp. was associated with Corynebacterium pyogenes and Bacteroides spp. with Staphylococcus aureus and/or Streptococcus agalactiae in 80% anaerobic udder infections. Gram positive anaerobic species were mostly sensitive to penicillin-G but all the Gram negative rods were resistant. In addition, all B. fragilis strains produced beta-lactamase. The ability to produce heparinase was demonstrated in one strain of Peptococcus indolicus and a Peptostreptococcus sp.

[Bacteriological study of cefminox in the field of obstetrics and gynecology].

Cefminox (CMNX, MT-141), a new cephem antibiotic, was determined of its antibacterial activity against 304 clinical isolates with following results. CMNX was inferior to CEZ or CMZ in the activity against 78 isolates of Staphylococcus sp., but it was superior to these antibiotics in the activity against 104 isolates of E. coli. Against 53 isolates of Bacteroides sp., CMNX showed higher activity than CEZ or CMZ. In the activity against 69 isolates of Peptococcus sp. and Peptostreptococcus sp., CMNX was almost equal to CEZ.

[Antibacterial and bactericidal activity of tinidazole against anaerobic bacteria comparing with metronidazole (author's transl)].

Antibacterial activity of tinidazole (1-2-(ethylsulfonyl)-2-methyl-5-nitroimidazole) against anaerobic bacteria including Peptococcus, Peptostreptococcus, Eubacterium, Propionibacterium, Bacteroides and Fusobacterium was studied by agar dilution method comparing with metronidazole. In addition to this work, bactericidal effect of tinidazole and metronidazole against P. prevotii, B. fragilis ss. fragilis and F. varium was examined by quantitative culture method after incubation in GAM broth containing of 4 MIC, 2 MIC, 1 MIC and 1/2 MIC of both drugs against each of three strains for 1, 3, 6, 12 and 24 hours. All the strains of Peptococcus and Peptostreptococcus including P. anaerobius, P. saccharolyticus, P. prevotii and Ps. anaerobius and others were susceptible to a concentration of 6.25 mcg/ml of this drug. A concentration of 3.13 mcg/ml inhibited all strains of Bacteroides including B. fragilis ss. fragilis (12 strains), ss. vulgatus (5 strains), ss. thetaiotaomicron (4 strains) and ss. distasonis (2 strains). To this concentration all strains of Fusobacterium including F. varium (20 strains), F. mortiferum (2 strains) and other Fusobacterium sp. (5 strains) were susceptible. On the contrary, Propionibacterium acnes (6 strains) was resistant to 100 mcg/ml or more of tinidazole and metronidazole. The antibacterial activity of tinidazole was stronger against Bacteroides than that of metronidazole, while almost equal against Peptococcus, Peptostreptococcus, Eubacterium and Fusobacterium. Tinidazole was bactericidal against F. varium in a concentration of 2 MIC till 24 hours of incubation but did not show such an activity on B. fragilis ss. fragilis in same concentration even after 12 hours of incubation. On the other hand, metronidazole was bactericidal against B. fragilis ss. fragilis while was not against F. varium. Against P. prevotii bactericidal activity of both drugs was similar. Tinidazole as well as metronidazole is an excellent chemotherapeutic agent against anaerobic bacteria excluding Propionibacterium acnes and Bifidobacterium adolescentis.