Comparative in-vitro activity of cefoperazone/sulbactam and 11 other agents against multidrug resistant Bacteroides fragilis group species

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.

Synthesis and antibacterial activity of HMR 3647 a new ketolide highly potent against erythromycin-resistant and susceptible pathogens

In the search for new ketolides with improved activities against erythromycin-resistant S. pneumoniae and H. influenzae we synthesized a new 11,12 carbamate ketolide substituted by an imidazo-pyridyl side chain: HMR 3647. This compound demonstrated a potent activity against erythromycin susceptible and resistant pathogens, including penicillin G/erythromycin A-resistant S. pneumoniae and H. influenzae. In vivo, HMR 3647 displayed good pharmacokinetic parameters (Cmax = 2.9 microg/ml, bioavailability=49%, AUC0.8 = 17.2 microg.h/l, t1/2=1h) and was shown to have a high therapeutic efficacy in mice infected by various respiratory pathogens, including multi-resistant S. pneumoniae and Gram negative bacteria such as H. influenzae. HMR 3647 appears to be a very promising agent for the treatment of respiratory infections and is currently in clinical trials.

Decreased susceptibility of Streptococcus pneumoniae to fluoroquinolones in Canada. Canadian Bacterial Surveillance Network

BACKGROUND

Fluoroquinolones are now recommended for the treatment of respiratory tract infections due to Streptococcus pneumoniae, particularly when the isolates are resistant to beta-lactam antibiotics. Although pneumococci with reduced susceptibility to fluoroquinolones have been identified, their prevalence has not been determined in a defined population.

METHODS

We performed susceptibility testing on 7551 isolates of S. pneumoniae obtained from surveillance in Canada in 1988 and from 1993 to 1998. Pneumococci with reduced susceptibility to fluoroquinolones (defined as a minimal inhibitory concentration of ciprofloxacin of at least 4 microg per milliliter) were further characterized. We also examined antibiotic prescriptions dispensed in Canadian retail pharmacies.

RESULTS

Between 1988 and 1997, fluoroquinolone prescriptions increased from 0.8 to 5.5 per 100 persons per year. The prevalence of pneumococci with reduced susceptibility to fluoroquinolones increased from 0 percent in 1993 to 1.7 percent in 1997 and 1998 (P=0.01). Among adults, the prevalence increased from 1.5 percent in 1993 and 1994 combined to 2.9 percent in 1997 and 1998 combined. The prevalence was higher in isolates from older patients (2.6 percent among those 65 years of age or older vs. 1.0 percent among those 15 to 64 years of age, P<0.001) and among those from Ontario (1.5 percent, vs. 0.4 percent among those from the rest of Canada; P< 0.001). Fluoroquinolone use was greatest among the elderly and in Ontario. The 75 isolates (17 serotypes) of pneumococci with reduced susceptibility to fluoroquinolones were submitted by 40 laboratories in eight provinces. Reduced susceptibility to fluoroquinolones was associated with resistance to penicillin.

CONCLUSIONS

The prevalence of pneumococci with reduced susceptibility to fluoroquinolones is increasing in Canada, probably as a result of selective pressure from the increased use of fluoroquinolones.

Risk factors for carriage of respiratory pathogens in the nasopharynx of healthy children. Ascanius Project Collaborative Group

OBJECTIVES

To assess risk factors for nasopharyngeal carriage of Streptococcus pneumoniae, Haemophilus influenzae and Moraxella catarrhalis in a large sample of healthy children.

METHODS

In this point prevalence survey nasopharyngeal specimens were obtained from 1723 healthy children, ages 1 to 7 years, attending day-care centers or schools in 18 Italian cities. Written questionnaires for obtaining information about the demographics and medical history of the children were completed by the parents in the presence of a pediatrician.

RESULTS

The overall carrier rate of respiratory pathogens was 17.9% (S. pneumoniae, 3.5%; H. influenzae, 11.9%; M. catarrhalis, 4.1%). Only 5% of S. pneumoniae strains were penicillin-resistant whereas approximately 40% were erythromycin-resistant. Beta-lactamase production was found in 5.8% of H. influenzae and 88.7% of M. catarrhalis isolates. By multivariate analysis age (< or = 3 years), having older siblings, a history of prolonged full-time day-care attendance and living in a rural area significantly influenced the odds of carrying nasopharyngeal respiratory pathogens, particularly in children ages 1 to 5 years. Sex, breastfeeding, passive smoking and recent upper respiratory tract infections were not significant variables. Antibiotic treatment in the previous 3 months did not affect nasopharyngeal carriage, whereas repeated treatments with a macrolide were associated with carriage of S. pneumoniae.

CONCLUSIONS

Our results suggest that there is a strong and long term relationship between exposure to large numbers of children in the first years of life and nasopharyngeal carriage of all respiratory pathogens. In addition antimicrobial restrictive guidelines should be tailored to local microbiologic sceneries.

Antibiotic management of pneumococcal infections in an era of increased resistance

Pneumococci are a leading cause of bacterial meningitis and bacteraemia, as well as pneumonia, otitis media and sinusitis in childhood. These organisms recently have shown a dramatic increase in antibiotic resistance. Penicillin-resistant pneumococci are of special concern as they are often resistant to other unrelated antibiotics. This is of particular significance to Aboriginal children who have among the highest rates of pneumococcal infection in the world. Laboratories should now test all invasive pneumococcal isolates for penicillin and third generation cephalosporin resistance. Local treatment guidelines are required for pneumococcal infections, especially for meningitis, taking into account the prevalence of resistant strains within the community. At present, penicillin and amoxycillin remain the drugs of choice for pneumococcal infections, with the exception of meningitis where initial empirical therapy must be with a third generation cephalosporin. Judicious antibiotic use, which avoids over-prescribing and unnecessary use of broad-spectrum agents, improved living standards in underprivileged communities and introduction of an effective conjugate vaccine, able to reduce the rates of pneumococcal infection and hopefully colonization, may limit the spread of resistant strains.