Predictors of death after severe Streptococcus pyogenes infection.

An evaluation of the relative importance of host and pathogen factors on the survival rate of patients with invasive Streptococcus pyogenes infection found a number of clinical and demographic factors to be associated with risk for death. Some evidence suggested a seasonal pattern to patient survival rate.

Prevalence and mechanisms of cephalosporin resistance in Enterobacteriaceae in London and South-East England.

OBJECTIVES: To investigate the molecular epidemiology of Enterobacteriaceae producing extended-spectrum beta-lactamases (ESBLs) in London and South-East England. METHODS: A prospective study involving 16 hospital microbiology laboratories in London and South-East England was undertaken over a 12 week period. Each laboratory submitted up to 100 consecutive cephalosporin-resistant Enterobacteriaceae isolates judged clinically significant by microbiology staff. Centralized testing was undertaken to confirm organism identification and cephalosporin resistance and to analyse resistance mechanisms. RESULTS: The predominant mechanism of cephalosporin resistance in isolates from both hospital and community settings was the production of CTX-M-type ESBLs, with CTX-M-producing Escherichia coli as the most numerous resistant organism overall. Other major mechanisms of cephalosporin resistance included production of non-CTX-M ESBLs and AmpC beta-lactamases. Most ESBL (both CTX-M and non-CTX-M) producers were multiply resistant to non-beta-lactam antibiotics, including trimethoprim, ciprofloxacin and gentamicin. CONCLUSIONS: CTX-M enzymes, which were unrecorded in the UK prior to 2000, have become the major mechanism of cephalosporin resistance in Enterobacteriaceae in South-East England. E. coli has overtaken Klebsiella and Enterobacter spp. to become the major host for ESBLs. Due to the multiple antibiotic resistance exhibited by many ESBL-producers, these changes have major implications for antimicrobial therapy.

Antimicrobial susceptibility of the pathogens of bacteraemia in the UK and Ireland 2001-2002: the BSAC Bacteraemia Resistance Surveillance Programme.

OBJECTIVES: To describe the current patterns of antimicrobial resistance in the major pathogens of bacteraemia in the UK and Ireland, to highlight any unexpected resistance patterns and to act as a reference baseline for future studies. METHODS: In 2001 and 2002, 5092 blood culture isolates were collected by 29 laboratories distributed across the UK and Ireland. A single central laboratory re-identified the isolates and measured MICs by the BSAC agar dilution method. RESULTS: Oxacillin resistance was found in 42% of Staphylococcus aureus and 76% of coagulase-negative staphylococci. Streptococci were generally susceptible to beta-lactams, but tetracycline resistance was common (except in Streptococcus pneumoniae) and particularly common among group B isolates (82% resistant). Nine percent of S. pneumoniae had reduced susceptibility to penicillin (MICs 0.12-1 mg/L), but none required >/=2 mg/L for inhibition. High-level gentamicin resistance was seen in 43% of Enterococcus faecalis, often in combination with raised ciprofloxacin MICs (>/=32 mg/L), but these isolates remained susceptible to ampicillin and imipenem. Only linezolid and tigecycline showed in vitro potency against a large proportion of Enterococcus faecium. Vancomycin resistance was restricted to enterococci (20% of E. faecium, 3% of E. faecalis) and a single isolate of coagulase-negative staphylococci (0.2%, MIC of 8 mg/L). Escherichia coli isolates were commonly resistant to amoxicillin (56%) and tetracycline (88%) but remained susceptible to ceftazidime, piperacillin/tazobactam and imipenem. Extended-spectrum beta-lactamases were detected in 2% of E. coli (none in 2001, 3.2% in 2002), 5% of Klebsiella spp. and 8% of Enterobacter spp. Resistance rates of Pseudomonas aeruginosa to ciprofloxacin, ceftazidime, gentamicin, imipenem and piperacillin/tazobactam were between 4% and 7%. Among the newly licensed and developmental agents, there was no resistance to linezolid in Gram-positive organisms. Ertapenem had a wide spectrum, covering Enterobacteriaceae, streptococci and oxacillin-susceptible staphylococci. MICs of tigecycline were low for Gram-positive species and Enterobacteriaceae except Proteeae and Enterobacter spp. CONCLUSION: Antimicrobial resistance among major bloodstream pathogens to those antimicrobials often selected for empirical therapy was relatively uncommon in 2001-2002, usually <10%. An important exception was oxacillin resistance in S. aureus.

Ciprofloxacin-resistant Escherichia coli from bacteraemias in England; increasingly prevalent and mostly from men.

OBJECTIVES: To assess ciprofloxacin resistance among Escherichia coli isolates from bacteraemia patients in England in relation to age, sex and Region. METHODS: Routine susceptibility data for bacteraemia isolates were collected from over 90% of hospitals in England. RESULTS: During 1995-2001, the prevalence of ciprofloxacin resistance trebled, from 2.1% to 6.5%. Isolates from men were more frequently resistant than those from women, possibly because infections in men more often involve nosocomial strains. Resistance was rare (<1.5%) in isolates from patients aged <1 year; among older patients, resistance was unrelated to age in isolates from women, but peaked in the 15-44 age group for men. CONCLUSIONS: The prevalence of ciprofloxacin resistance in E. coli from bacteraemia is strongly associated with sex and, to a lesser extent, age.