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The genus Lactobacillus is a taxonomically complex and is composed of over 170 species that cannot be easily differentiated phenotypically and often require molecular identification. Although they are part of the normal human gastrointestinal and vaginal flora, they can also be occasional human pathogens. They are extensively used in a variety of commercial products including probiotics. Their antimicrobial susceptibilities are poorly defined in part because of their taxonomic complexity and are compounded by the different methods recommended by Clinical Laboratory Standards Institute and International Dairy Foundation. Their use as probiotics for prevention of Clostridium difficile infection is prevalent among consumers worldwide but raises the question of will the use of any concurrent antibiotic effect their ability to survive. Lactobacillus species are generally acid resistant and are able to survive ingestion. They are generally resistant to metronidazole, aminoglycosides and ciprofloxacin with L. acidophilus being susceptible to penicillin and vancomycin, whereas L. rhamnosus and L. casei are resistant to metronidazole and vancomycin.

Despite the high incidence of odontogenic abscesses in pet rabbits, published data on the bacteriology of these infections are lacking, and clinical cultures are often ambiguous, making antibiotic choices difficult. In order to define the bacteriology of these infections, 12 rabbit mandibular and maxillary abscesses were cultured aerobically and anaerobically. All specimens yielded pathogenic bacteria, including Fusobacterium nucleatum, Prevotella heparinolytica, Prevotella spp., Peptostreptococcus micros, Streptococcus milleri group, Actinomyces israelii, and Arcanobacterium haemolyticum. These organisms are consistent with the characterized bacteriology of periodontal disease in human and other mammalian studies. The isolates were tested against 10 antimicrobial agents commonly used to treat rabbits; 100% of the strains tested were susceptible to clindamycin, 96% were susceptible to penicillin and ceftriaxone, 54% were susceptible to ciprofloxacin, and only 7% were susceptible to trimethoprim-sulfamethoxazole.Odontogenic abscesses in rabbits are common and often lead to significant morbidity and mortality (10). Treatment of these abscesses is frequently unsuccessful because of aggressive capsule formation and the development of fistulous tracts. The thick consistency of rabbit pus makes aspiration and drainage of these abscesses very difficult and antibiotic therapy problematic; therefore, surgical excision of the abscesses is often the best treatment option. However, since the abscess tracts may be microscopic and thus visually undetectable, total excision is difficult and recurrence of the infection is likely. Osteomyelitis and retrobulbar involvement are common sequelae.The lack of published data on the microbiology of odontogenic abscesses in rabbits has made interpretation of culture reports difficult, and the antibiotic treatment options remain unclear. Less-than-optimum specimen collection techniques that do not exclude normal gingival flora can produce ambiguous culture results. Additionally, because rabbits are coprophagic herbivores, cultures of molar pocket pus instead of the abscess capsule may grow organisms not generally considered to be oral pathogens in other mammals; members of the family Enterobacteriaceae and Bacteroides fragilis group and environmental contaminants such as Pseudomonas and Acinetobacter spp. are often isolated from such specimens. Therapy directed against these organisms alone has frequently consisted of an aminoglycoside and has typically been ineffective. In addition, routine culture and identification of oral pathogens have often been unsuccessful (28,29). And when mixed oral organisms are isolated from these specimens, culture reports of "oral flora isolated" may not preclude such pathogens as the Streptococcus milleri group or Actinomyces israelii. Finally, susceptibility testing of these organisms is problematic and thus not usually performedIn lieu of adequate clinical data, empirical antibiotic therapy has often been directed against established rabbit pathogens such...

To better characterize murine intestinal microbiota, a large number (187) of Gram-positive-staining, rod- and coccoid-shaped, and facultatively or strictly anaerobic bacteria were isolated from small and large intestinal contents from mice. Based on 16S rRNA gene sequencing, a total 115 isolates formed three phylogenetically distinct clusters located within the family Erysipelotrichaceae. Group 1, as represented by strain NYU-BL-A3T, was most closely related to Allobaculum stercoricanis, with 16S rRNA gene sequence similarity values of 87.7 %. A second group, represented by NYU-BL-A4T, was most closely related to Faecalibaculum rodentium, with 86.6 % 16S rRNA gene sequence similarity. A third group had a nearly identical 16S rRNA gene sequence (99.9 %) compared with the recently described Faecalibaculum rodentium, also recovered from a laboratory mouse; however, this strain had a few differences in biochemical characteristics, which are detailed in an emended description. The predominant (>10 %) cellular fatty acids of strain NYU-BL-A3T were C16 : 0 and C18 : 0, and those of strain NYU-BL-A4T were C10 : 0, C16 : 0, C18 : 0 and C18 : 1ω9c. The two groups could also be distinguished by multiple biochemical reactions, with the group represented by NYU-BL-A4T being considerably more active. Based on phylogenetic, biochemical and chemotaxonomic criteria, two novel genera are proposed, Ileibacterium valens gen. nov., sp. nov. with NYU-BL-A3T (=ATCC TSD-63T=DSM 103668T) as the type strain and Dubosiella newyorkensis gen. nov., sp. nov. with NYU-BL-A4T (=ATCC TSD-64T=DSM 103457T) as the type strain.

Tests of dalbavancin's in vitro activity against 209 aerobic and 120 anaerobic isolates from pretreatment diabetic foot infections showed an MIC 90 of <0.125 g/ml against methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), and 120 anaerobes (Clostridium perfringens, other clostridia, Peptoniphilus asaccharolyticus, Finegoldia magna, and Anaerococcus prevotii), compared to respective MIC 90 s for MSSA and MRSA of 0.5 and 1 g/ml for vancomycin, 4 and 4 g/ml for linezolid, 0.5 and 0.5 g/ml for daptomycin, and 0.25 and >8 g/ml for clindamycin.Diabetes will affect ϳ14.5 million Americans by 2010 (8), and diabetic foot infections (DFIs) account for 20% of all hospitalizations of diabetic patients (1). DFIs are often multibacterial with aerobic and anaerobic bacteria. Recently, community-acquired methicillin-resistant Staphylococcus aureus (MRSA) (2,3,14) has accounted for 50% of all S. aureus skin and skin structure infection (SSTI) isolates (2,3,14). Previously, we noted (6) that MRSA was isolated from 20% of DFIs. As a reference lab for a DFI study, we received 473 pretreatment specimens, of which 91.3% grew aerobic bacteria, including 48% that grew S. aureus as one of the isolates (one-quarter of which were MRSA), and 41.6% grew anaerobes, with anaerobic gram-positive cocci the most common isolates.Dalbavancin (BI397) is new glycopeptide (4, 10) with good activity against gram-positive organisms, including MRSA, but none against gram-negative organisms (13,19). Dalbavancin has a long elimination half-life (ϳ8.5 days) and has been effective in treating gram-positive SSTIs (9, 18) with a two-dose regimen. For DFIs, an antimicrobial agent with a long half-life, especially one administered once weekly, seems to be advantageous.Specimens were obtained from patients with clinical infection who had not received antimicrobials within 48 h and after wound debridement. To avoid bias, 329 consecutively isolated gram-positive aerobic and anaerobic organisms were selected for this study. Isolates were identified by standard criteria (12, 15) and stored in skim milk at Ϫ70°C. Frozen anaerobic cultures were subcultured twice onto brucella agar supplemented with hemin, vitamin K 1 , and 5% sheep blood (Anaerobe Systems, Morgan Hill, CA) to ensure purity and good growth. Aerobic strains were subcultured to Trypticase soy blood agar. Susceptibility testing was performed according to CLSI (formerly NCCLS) standards M11-A6 (17) and M7-A6 (16).The types and numbers of strains tested are shown in Table 1. Laboratory-standard reference powders were either obtained from their manufacturers or purchased from Sigma Chemicals (St. Louis, MO).The MICs for anaerobes were determined by the agar dilution method using brucella agar supplemented with hemin, vitamin K 1 , and 5% laked sheep blood. Antimicrobial agents were reconstituted according to the manufacturers' instructions. Serial twofold dilutions of dalbavancin were prepared at 100-fold the final concentration in dimethyl sulfoxide on the day of t...

Telavancin is a new semisynthetic glycopeptide anti-infective with multiple mechanisms of action, including inhibition of bacterial membrane phospholipid synthesis and inhibition of bacterial cell wall synthesis. We determined the in vitro activities of telavancin, vancomycin, daptomycin, linezolid, quinupristin-dalfopristin, imipenem, piperacillin-tazobactam, and ampicillin against 268 clinical isolates of anaerobic gram-positive organisms and 31 Corynebacterium strains using agar dilution methods according to National Committee for Clinical Laboratory Standards procedures. Plates with daptomycin were supplemented with Ca 2؉ to 50 mg/liter. The MICs at which 90% of isolates tested were inhibited (MIC 90 s) for telavancin and vancomycin were as follows: Actinomyces spp. (n ‫؍‬ 45), 0.25 and 1 g/ml, respectively; Clostridium difficile (n ‫؍‬ 14), 0.25 and 1 g/ml, respectively; Clostridium ramosum (n ‫؍‬ 16), 1 and 4 g/ml, respectively; Clostridium innocuum (n ‫؍‬ 15), 4 and 16 g/ml, respectively; Clostridium clostridioforme (n ‫؍‬ 15), 8 and 1 g/ml, respectively; Eubacterium group (n ‫؍‬ 33), 0.25 and 2 g/ml, respectively; Lactobacillus spp. (n ‫؍‬ 26), 0.5 and 4 g/ml, respectively; Propionibacterium spp. (n ‫؍‬ 34), 0.125 and 0.5 g/ml, respectively; Peptostreptococcus spp. (n ‫؍‬ 52), 0.125 and 0.5 g/ml, respectively; and Corynebacterium spp. (n ‫؍‬ 31), 0.03 and 0.5 g/ml, respectively. The activity of TD-6424 was similar to that of quinupristin-dalfopristin for most strains except C. clostridioforme and Lactobacillus casei, where quinupristin-dalfopristin was three-to fivefold more active. Daptomycin had decreased activity (MIC > 4 g/ml) against 14 strains of Actinomyces spp. and all C. ramosum, Eubacterium lentum, and Lactobacillus plantarum strains. Linezolid showed decreased activity (MIC > 4 g/ml) against C. ramosum, two strains of C. difficile, and 15 strains of Lactobacillus spp. Imipenem and piperacillin-tazobactam were active against >98% of strains. The MICs of ampicillin for eight Clostridium spp. and three strains of L. casei were >1 g/ml. The MIC 90 of TD-6424 for all strains tested was <2 g/ml. TD-6424 has potential for use against infections with gram-positive anaerobes and deserves further clinical evaluation.The development of resistance in gram-positive organismsincluding Staphylococcus aureus resistant to oxacillin and vancomycin (10,11,13) and linezolid (12) and vancomycinresistant enterococci also resistant to linezolid (4)-has accentuated the need for new antimicrobial agents. Telavancin is a novel glycopeptide that is bactericidal and shows concentration-dependent killing against gram-positive aerobes, including vancomycin-resistant strains (9). Unlike vancomycin, TD-6424 has multiple synergistic mechanisms of action resulting in TD-6424's enhanced activity against aerobic gram-positive species (5a, 9). At the MIC, it has exhibited postantibiotic effects of up to 6 h against S. aureus, compared to 2 h for vancomycin (9). TD-6424 is currently in phase 2 trials for serious gram-positive infe...

Serum concentrations of oral linezolid in this patient population were diminished compared with those of healthy volunteers, but still provided prolonged serum inhibitory activity against common pathogens associated with skin/soft tissue infections. One treatment concern would be an obese patient receiving oral linezolid who was infected with a less susceptible (MIC > or =4.0 microg/mL) strain of S. aureus. Bactericidal activity was also observed against selective pathogens.

Against 443 aerobic and anaerobic bacteria isolated from diabetic foot infections, ceftobiprole MICs (g/ml) at which 90% of the isolates tested were inhibited were as follows: methicillin-resistant Staphylococcus aureus, 1; methicillin-susceptible S. aureus and Staphylococcus lugdunensis, 0.5; Anaerococcus prevotii, 0.125; Finegoldia magna, 0.5; Peptoniphilus asaccharolyticus, 1; Peptostreptococcus anaerobius, 4; Escherichia coli and Enterobacter species, 0.125; Klebsiella species, 2; and Pseudomonas aeruginosa, 8.Diabetic foot infections (DFIs) are common complications and account for ϳ20% of all hospitalizations for Ͼ18 million diabetics in the United States (1, 2). Early-stage DFIs are generally due to Staphylococcus aureus, and 20% of hospitalized DFI patients grow methicillin-resistant S. aureus (MRSA) (7); more-advanced DFIs involve aerobic gram-negative rods, and 45% also involve anaerobes (4.1 to 5.8 bacterial species isolated per specimen, composed of 2.9 to 3.5 aerobes and 1.2 to 2.6 anaerobes) (6 Ceftobiprole (BAL 9141) is a new broad-spectrum pyrrolidinone cephem antimicrobial active against S. aureus bacteria, including MRSA and vancomycin-intermediate S. aureus, vancomycin-resistant Enterococcus faecalis (but not ampicillin-resistant enterococci), other gram-positive organisms, and many gram-negative rods except Proteus vulgaris or extended-spectrum beta-lactamase (ESBL)-producing strains of Enterobacteriaceae (3,5,8,9,15), but data on its activity against anaerobes are limited (14).Consequently, we studied the activity of ceftobiprole against 443 aerobic and anaerobic strains isolated from pretreatment cultures (2001 to 2004) obtained after debridement from patients with symptomatic, complicated DFIs at 52 domestic clinical study sites and sent to our lab via overnight courier. All isolates (Table 1) were identified by standard criteria (10, 11). Standard antimicrobial laboratory powders were supplied by the manufacturers and reconstituted accordingly.Anaerobic susceptibility testing was performed by the agar dilution method according to CLSI standard M11-A6 (12) with a final inoculum of 10 5 CFU/spot. Plates were incubated at 37°C for 44 to 48 h in an anaerobic chamber (Anaerobe Systems, California). Aerobic isolates were subcultured onto Trypticase soy blood agar and tested by the broth microdilution method using cation-adjusted Mueller-Hinton broth, with lysed horse blood supplementation for streptococci and corynebacteria (4, 13). The trays were prepared in-house with serial twofold dilutions of the drugs by using the Quick-Spense apparatus (Sally Spring Instrument Co. Inc., Germantown, MD) and stored at Ϫ70°C until use. Colonies were suspended from overnight growth and added to the trays for a final inoculum of approximately 5 ϫ 10 5 CFU/ml. The trays were incubated for 18 to 24 h and examined.Results are presented in Table 1. The ceftobiprole quality control strain MICs were as follows: S. aureus ATCC 29213, 0.25 g/ml, seven times; 0.5 g/ml, twice; Escherichia coli ATCC 25922, 0.03 g/ml, onc...