Parabacteroides distasonis:intriguing aerotolerant gut anaerobe with emerging antimicrobial resistance and pathogenic and probiotic roles in human health

Parabacteroides distasonis is the type strain for the genus Parabacteroides, a group of gram-negative anaerobic bacteria that commonly colonize the gastrointestinal tract of numerous species. First isolated in the 1930s from a clinical specimen as Bacteroides distasonis, the strain was re-classified to form the new genus Parabacteroides in 2006. Currently, the genus consists of 15 species, 10 of which are listed as 'validly named' (P. acidifaciens, P. chartae, P. chinchillae, P. chongii, P. distasonis, P. faecis, P. goldsteinii, P. gordonii, P. johnsonii, and P. merdae) and 5 'not validly named' (P. bouchesdurhonensis, P. massiliensis, P. pacaensis, P. provencensis, and P. timonensis) by the List of Prokaryotic names with Standing in Nomenclature. The Parabacteroides genus has been associated with reports of both beneficial and pathogenic effects in human health. Herein, we review the literature on the history, ecology, diseases, antimicrobial resistance, and genetics of this bacterium, illustrating the effects of P. distasonis on human and animal health

The status of the world's land and marine mammals: diversity, threat, and knowledge

Knowledge of mammalian diversity is still surprisingly disparate, both regionally and taxonomically. Here, we present a comprehensive assessment of the conservation status and distribution of the world's mammals. Data, compiled by 1700+ experts, cover all 5487 species, including marine mammals. Global macroecological patterns are very different for land and marine species but suggest common mechanisms driving diversity and endemism across systems. Compared with land species, threat levels are higher among marine mammals, driven by different processes (accidental mortality and pollution, rather than habitat loss), and are spatially distinct (peaking in northern oceans, rather than in Southeast Asia). Marine mammals are also disproportionately poorly known. These data are made freely available to support further scientific developments and conservation action

Changes in Serotypes and Antimicrobial Susceptibility of Invasive Streptococcus pneumoniae Strains in Cleveland: a Quarter Century of Experience▿

The serotypes and susceptibilities to penicillin, macrolides, and clindamycin of 1,655 invasive isolates of Streptococcus pneumoniae recovered between 1979 and 2004 were determined. A precipitous decrease of 61% in the number of isolates was found following 2000, the year of 7-valent protein-conjugated pneumococcal vaccine (PCV7) introduction (139 versus 55 per 2-year period prior to versus after 2000; P < 0.001). This decrease was 84% in children <5 years old (80 versus 13 per 2-year period; P < 0.001) and 18 to 23% in other age groups (P, not significant). PCV7 serotypes decreased by 76% overall (103 versus 25 per 2-year period; P < 0.001) and by 92% in children <5 years old (65 versus 5 per 2-year period; P < 0.001), with significant decreases in six of the seven PCV serotypes. Other serotypes, except for type 19A, decreased from 32 to 22 per 2-year period, while type 19A increased from 4 to 8 per 2-year period, although none of these changes reached significance. Drug resistance emerged slowly, with the first penicillin-intermediate strain isolated in 1980 and the first macrolide/lincosamide-resistant strain isolated in 1984. The first penicillin-resistant strain was isolated in 1993. Resistance increased steadily thereafter until 2003-2004, when 51.1% of isolates were penicillin nonsusceptible and 53.3% were macrolide resistant. Clindamycin resistance remained low until 2003-2004, when 26.7% of strains were resistant; this was associated with the emergence of multidrug-resistant type 19A strains. This study documents the emergence of resistance over a quarter century among invasive pneumococci in the Cleveland area, as well as the reduction in disease caused by PCV7 serotypes following the introduction of PCV7 in 2000

Activity of Retapamulin against Streptococcus pyogenes and Staphylococcus aureus Evaluated by Agar Dilution, Microdilution, E-Test, and Disk Diffusion Methodologies

The in vitro activity of retapamulin against 106 Staphylococcus aureus isolates and 109 Streptococcus pyogenes isolates was evaluated by the agar dilution, broth microdilution, E-test, and disk diffusion methodologies. Where possible, the tests were performed by using the CLSI methodology. The results of agar dilution, broth microdilution, and E-test (all with incubation in ambient air) for S. aureus yielded similar MICs, in the range of 0.03 to 0.25 μg/ml. These values corresponded to zone diameters between 25 and 33 mm by the use of a 2-μg retapamulin disk. Overall, 99% of the agar dilution results and 95% of E-test results for S. aureus were within ±1 dilution of the microdilution results. For S. pyogenes, the MICs obtained by the agar and broth microdilution methods (both after incubation in ambient air) were in the range of 0.008 to 0.03 μg/ml, and E-test MICs (with incubation in ambient air) were 0.016 to 0.06 μg/ml. For S. pyogenes, 100% of the agar dilution MIC results were within ±1 dilution of the broth microdilution results. E-test MICs (after incubation in ambient air) were within ±1 and ±2 dilutions of the broth microdilution results for 76% and 99% of the isolates, respectively. E-test MICs for S. pyogenes strains in CO(2) were up to 4 dilutions higher than those in ambient air. Therefore, it is recommended that when retapamulin MICs are determined by E-test, incubation be done in ambient air and not in CO(2), due to the adverse effect of CO(2) on the activity of this compound. Diffusion zones (with incubation in CO(2)) for S. pyogenes were 18 to 24 mm. Retapamulin MICs for all strains by all methods (with incubation in ambient air) were ≤0.25 μg/ml. These results demonstrate that S. pyogenes (including macrolide-resistant strains) and S. aureus (including methicillin-resistant and vancomycin-nonsusceptible strains) are inhibited by very low concentrations of retapamulin and that all four testing methods are satisfactory for use for susceptibility testing

Changes in Serotypes and Antimicrobial Susceptibility of Invasive Streptococcus pneumoniae Strains in Cleveland: a Quarter Century of Experience▿

The serotypes and susceptibilities to penicillin, macrolides, and clindamycin of 1,655 invasive isolates of Streptococcus pneumoniae recovered between 1979 and 2004 were determined. A precipitous decrease of 61% in the number of isolates was found following 2000, the year of 7-valent protein-conjugated pneumococcal vaccine (PCV7) introduction (139 versus 55 per 2-year period prior to versus after 2000; P < 0.001). This decrease was 84% in children <5 years old (80 versus 13 per 2-year period; P < 0.001) and 18 to 23% in other age groups (P, not significant). PCV7 serotypes decreased by 76% overall (103 versus 25 per 2-year period; P < 0.001) and by 92% in children <5 years old (65 versus 5 per 2-year period; P < 0.001), with significant decreases in six of the seven PCV serotypes. Other serotypes, except for type 19A, decreased from 32 to 22 per 2-year period, while type 19A increased from 4 to 8 per 2-year period, although none of these changes reached significance. Drug resistance emerged slowly, with the first penicillin-intermediate strain isolated in 1980 and the first macrolide/lincosamide-resistant strain isolated in 1984. The first penicillin-resistant strain was isolated in 1993. Resistance increased steadily thereafter until 2003-2004, when 51.1% of isolates were penicillin nonsusceptible and 53.3% were macrolide resistant. Clindamycin resistance remained low until 2003-2004, when 26.7% of strains were resistant; this was associated with the emergence of multidrug-resistant type 19A strains. This study documents the emergence of resistance over a quarter century among invasive pneumococci in the Cleveland area, as well as the reduction in disease caused by PCV7 serotypes following the introduction of PCV7 in 2000

Effects of Various Test Media on the Activities of 21 Antimicrobial Agents against Haemophilus influenzae

As considerable variation in the antimicrobial susceptibility of Haemophilus influenzae has been reported, the effects of various test media on the susceptibility of H. influenzae were studied. MICs were determined by three laboratories for 21 antimicrobial agents against a panel of 100 selected isolates. Testing was performed using a reference NCCLS frozen broth microdilution method with Haemophilus test medium (HTM) broth and dried commercial MIC trays rehydrated with the following media: in-house and commercially prepared HTM broth, Mueller-Hinton broth with 2% lysed horse blood and NAD, IsoSensitest broth with 2% lysed horse blood and NAD, and IsoSensitest broth-based HTM. Overall, all results were very reproducible, with the MIC at which 50% of the isolates tested are inhibited (MIC(50)), MIC(90), and geometric mean MIC being within one doubling dilution by all six methods and at all three testing centers for 15 of the 21 agents tested. Interlaboratory differences were more marked than intralaboratory differences or differences among media. Cefprozil, cefaclor, and trimethoprim-sulfamethoxazole results differed the most, while results for ampicillin, amoxicillin-clavulanic acid, cefdinir, cefixime, ceftriaxone, and clarithromycin were the most reproducible. However, these variations in results caused considerable differences in susceptibility rates for agents for which NCCLS susceptible breakpoints were close to the geometric mean MIC, particularly for cefaclor and cefprozil. This was much less of a problem when pharmacokinetic-pharmacodynamic breakpoints were used. Reproducible susceptibility results were obtained for a wide range of agents against H. influenzae in three laboratories using a variety of media that support the growth of this fastidious species

Activity of Ceftaroline against Recent Emerging Serotypes of Streptococcus pneumoniae in the United States▿

The in vitro activity of ceftaroline against 891 pneumococci collected in 2008 from 22 centers in the United States was investigated. Ceftaroline was the most potent agent tested, with the MICs being <0.008 to 0.5 μg/ml and the MIC90s being <0.008 to 0.25 μg/ml against 11 prevailing serotypes. The overall rates of susceptibility were as follows: penicillin G, 86.2%; ceftriaxone, 90.7%; cefuroxime, 70.1%; erythromycin, 61.6%; clindamycin, 79.2%; levofloxacin, 99.4%; and vancomycin, 100%. Serotype 19A isolates were the least susceptible. These results support the use of ceftaroline for the treatment of pneumococcal infections, including those caused by pneumococci resistant to other agents

Mycobactericidal activity of bedaquiline plus rifabutin or rifampin in <i>ex vivo</i> whole blood cultures of healthy volunteers: A randomized controlled trial - Fig 4

<p>Whole blood bactericidal activity (WBA) observed for bedaquiline plus either rifabutin (left) or rifampin (right) in relation to that predicted as the sum of the activities of each drug alone, based on plasma concentrations.</p