Geographically-based evaluation of multidrug resistance trends among Streptococcus pneumoniae in the USA: findings of the FAST surveillance initiative (2003-2004).

Surveillance initiatives to track Streptococcus pneumoniae resistance trends are important for understanding the current in vitro effectiveness of available antimicrobial agents. The antimicrobial susceptibility profiles of S. pneumoniae (n=1479 isolates) collected from 17 geographical areas across the USA (2003-2004) were analysed; 36.8% of isolates were resistant to one or more agents (24.4% were multidrug-resistant, i.e. resistant to two or more antimicrobial classes). Multidrug resistance involved resistance to beta-lactams, macrolides, tetracycline and trimethoprim/sulphamethoxazole, but rarely fluoroquinolones (>96% of multidrug-resistant isolates were fluoroquinolone-susceptible). Multidrug resistance rates were prominent regardless of the geographical region surveyed. As this trend continues, the empirical therapeutic options for S. pneumoniae infections will diminish and there will be an ongoing need to evaluate the effectiveness of potent fluoroquinolones such as gemifloxacin.

Rates of antimicrobial resistance among common bacterial pathogens causing respiratory, blood, urine, and skin and soft tissue infections in pediatric patients.

Antimicrobial resistance patterns among the principal bacterial pathogens from infections of the respiratory tract, blood, skin and soft tissue, and urinary tract of pediatric patients from the USA, Canada, Germany, France, and Italy were studied using the The Surveillance Network (TSN) database. Among Streptococcus pneumoniae isolates from respiratory tract infections, the prevalence of high-level penicillin resistance (MIC>/=2 microg/ml) ranged from 1.1 (Italy) to 36.2% (USA); erythromycin resistance was higher, ranging from 13.4 (Germany) to 63.8% (France). The prevalence of beta-lactamase-positive Haemophilus influenzae among isolates from lower respiratory tract infections ranged from <10 (Italy and Germany) to 38.4% (USA). Among isolates from blood and skin and soft tissue infections, the prevalence of methicillin-resistant Staphylococcus aureus (MRSA) ranged from 7.2% (Canada and Germany) to 27.3% (Italy). The prevalence of Escherichia coli and Klebsiella pneumoniae with putative extended-spectrum beta-lactamases among isolates from blood, urinary tract, and skin and soft tissue infections ranged from 0 (Germany and France) to 29.6% (Italy). With the exception of pseudomonal infections or infections with MRSA, amoxicillin-clavulanate retained moderate activity, whilst ceftriaxone and cefepime were the most effective broad-spectrum injectable agents. Meropenem was the most effective agent against Pseudomonas aeruginosa with <5% resistance. Low levels of resistance, along with acceptable safety profiles and the availability of convenient oral formulations, continue to support the use of ceftriaxone, cefepime, amoxicillin-clavulanate, and meropenem as viable options for the treatment of infections in pediatric patients.

Antibiotic susceptibility of isolates of Bacillus anthracis, a bacterial pathogen with the potential to be used in biowarfare.

Bacillus anthracis is a bacterial species that could be used in a bioterrorist attack. We tested a collection of isolates with a range of relevant antimicrobial compounds. All isolates tested were susceptible to ciprofloxacin and doxycycline. Penicillin and amoxicillin, with or without clavulanate, showed in vitro activity against all B. anthracis isolates. Ceftriaxone demonstrated lower-level in vitro activity compared to penicillin-related compounds against B. anthracis. In vitro data from this study are in keeping with available guidelines.

Comparative activity of cefditoren and other oral beta-lactams against nonpneumococcal streptococci.

BACKGROUND: In vitro studies of cefditoren activity have focused primarily on Streptococcus pneumoniae and other bacterial species isolated from patients with respiratory infections, but relatively few reports have been published describing the activity of cefditoren against clinical isolates of nonpneumococcal streptococci. METHODS: Cefditoren activity was determined by broth microdilution (M7-A5, NCCLS, 2000) for 450 viridans group streptococci, 917 Streptococcus pyogenes and 800 other beta-hemolytic streptococci collected throughout the US during 1999-2000. RESULTS: Against viridans group streptococci, cefditoren (MIC(90), 0.5 microg/ml) was 4- to 32-fold more active than the other beta-lactams tested (penicillin ampicillin, amoxicillin-clavulanate, cefprozil and cefuroxime). The difference in activity between cefditoren and the other beta-lactams was greater for penicillin-nonsusceptible isolates (MIC(90s), 1 microg/ml versus 8-32 microg/ml) than among penicillin-susceptible isolates (MIC(90s), 0.12 versus 0.25- 1 microg/ml). Cefditoren also demonstrated potent activity against S. pyogenes (MIC(90), 0.015 microg/ml) and other beta-hemolytic streptococci (MIC(90), 0.06 microg/ml), comparable to that of the other beta-lactams. CONCLUSIONS: The activity demonstrated by cefditoren against nonpneumococcal streptococci, including beta-lactam- and macrolide-resistant isolates, suggests that this agent holds promise as therapy for infections caused by all clinically significant species of streptococci.