Distinct Campylobacter fetus lineages adapted as livestock pathogens and human pathobionts in the intestinal microbiota.

Campylobacter fetus is a venereal pathogen of cattle and sheep, and an opportunistic human pathogen. It is often assumed that C. fetus infection occurs in humans as a zoonosis through food chain transmission. Here we show that mammalian C. fetus consists of distinct evolutionary lineages, primarily associated with either human or bovine hosts. We use whole-genome phylogenetics on 182 strains from 17 countries to provide evidence that C. fetus may have originated in humans around 10,500 years ago and may have "jumped" into cattle during the livestock domestication period. We detect C. fetus genomes in 8% of healthy human fecal metagenomes, where the human-associated lineages are the dominant type (78%). Thus, our work suggests that C. fetus is an unappreciated human intestinal pathobiont likely spread by human to human transmission. This genome-based evolutionary framework will facilitate C. fetus epidemiology research and the development of improved molecular diagnostics and prevention schemes for this neglected pathogen.

Detection, treatment, and prevention of carbapenemase-producing Enterobacteriaceae: recommendations from an International Working Group.

The prevalence of carbapenemase-producing Enterobacteriaceae (CPE) has increased during the past 10 years. Its detection is frequently difficult, because they do not always show a minimum inhibitory concentration (MIC) value for carbapenems in the resistance range. Both broth microdilution and agar dilution methods are more sensitive than disk diffusion method, Etest and automated systems. Studies on antimicrobial treatment are based on a limited number of patients; therefore, the optimal treatment is not well established. Combination therapy with two active drugs appears to be more effective than monotherapy. Combination of a carbapenem with another active agent--preferentially an aminoglycoside or colistin--could lower mortality provided that the MIC is ≤4 mg/l and probably ≤8 mg/l, and is administered in a higher-dose/prolonged-infusion regimen. An aggressive infection control and prevention strategy is recommended, including reinforcement of hand hygiene, using contact precautions and early detection of CPE through use of targeted surveillance.

Comparative in vitro activities of nemonoxacin, doripenem, tigecycline and 16 other antimicrobials against Nocardia brasiliensis, Nocardia asteroides and unusual Nocardia species.

OBJECTIVES: The aim of this study was to assess the in vitro activities of nemonoxacin (a novel non-fluorinated quinolone), doripenem, tigecycline and 16 other antimicrobial agents against the Nocardia species. METHODS: MICs of 19 antimicrobial agents for 125 clinical isolates of the Nocardia species were determined by the broth microdilution method. RESULTS: Nocardia brasiliensis (n = 61), Nocardia asteroides (n = 45), Nocardia flavorosea (n = 5), Nocardia otitidiscaviarum (n = 4), Nocardia farcinica (n = 3), Nocardia beijingensis (n = 2), Nocardia puris (n = 2) and one each of Nocardia nova, Nocardia jinanensis and Nocardia takedensis were identified based on a 16S rRNA gene sequencing analysis. For N. brasiliensis isolates, the MIC(90)s of the tested quinolones were in the order nemonoxacin < gemifloxacin = moxifloxacin < levofloxacin = ciprofloxacin, and the MIC(90)s of the tested carbapenems were in the order doripenem = meropenem < ertapenem < imipenem. Tigecycline had a lower MIC(90) (1 mg/L) than linezolid (8 mg/L). For N. asteroides isolates, the MIC(90)s of the tested quinolones were in the order nemonoxacin < gemifloxacin = moxifloxacin < levofloxacin < ciprofloxacin, and the MIC(90)s of the tested carbapenems were in the order doripenem = meropenem = imipenem < ertapenem. For the other 19 Nocardia species isolates, nemonoxacin showed good activity with the lowest MIC(90) of the tested quinolones. Among the four tested carbapenems, doripenem and meropenem had comparatively lower MIC(90)s. CONCLUSIONS: The results of this in vitro study suggest that nemonoxacin, linezolid and tigecycline show promise as treatment options for nocardiosis. Further investigation of their clinical role is warranted.

In vitro susceptibilities of aerobic and facultatively anaerobic Gram-negative bacilli isolated from patients with intra-abdominal infections worldwide: 2004 results from SMART (Study for Monitoring Antimicrobial Resistance Trends).

OBJECTIVES: SMART (Study for Monitoring Antimicrobial Resistance Trends) is an ongoing study to monitor worldwide antimicrobial resistance trends among aerobic and facultatively anaerobic Gram-negative bacilli (GNB) isolated from intra-abdominal infections. This 2004 report summarizes the most recently completed annual data from SMART. METHODS: During 2004, 81 medical centres from 28 countries in five global regions collected intra-abdominal GNB for antimicrobial susceptibility testing using broth microdilution according to the Clinical and Laboratory Standards Institute guidelines. RESULTS: A total of 6156 unique aerobic and facultatively anaerobic GNB were isolated from intra-abdominal infections. Enterobacteriaceae composed 86% of the total isolates. Among the 12 antimicrobial agents tested, the carbapenems and amikacin were the most consistently active against the Enterobacteriaceae. Escherichia coli was the most commonly isolated species (48%), and the susceptibility rate to the quinolones was lowest in Asia/Pacific and Latin America. Extended-spectrum beta-lactamases (ESBLs) were detected phenotypically in 10% of E. coli, 17% of Klebsiella spp. and 22% of Enterobacter spp. worldwide, representing a slight increase over the two previous years. ESBL producers typically had a more antibiotic-resistant profile than non-ESBL producers but were usually susceptible to the carbapenems. CONCLUSIONS: Antimicrobial resistance among GNB isolated from intra-abdominal infections continued to be a problem worldwide in 2004, with the highest rates of resistance overall in the Asia/Pacific region. The carbapenems and amikacin were the most consistently active agents in vitro against Enterobacteriaceae isolated from intra-abdominal infections worldwide.