David C. E. Speller

Resistance to methicillin and other antibiotics in isolates of Staphylococcus aureus from blood and cerebrospinal fluid, England and Wales, 1989-95

BACKGROUND Methicillin-resistant Staphylococcus aureus (MRSA) strains are colonising hospital patients in most areas of England and Wales, UK. The extent to which they cause invasive infection can be gauged from their presence in isolates from blood or cerebrospinal fluid. METHODS About 200 clinical laboratories reported the results of susceptibility testing of between 4501 and 6370 isolates of S aureus from blood or cerebrospinal fluid in each of the years 1989-95. We assessed the rate of resistance to methicillin and other antibiotics for each of these years. FINDINGS Resistance to methicillin was stable at about 1.5% of isolates during 1989-91, but increased thereafter to 13.2% in 1995 (p < 0.001). At the same time there was a significant increase in the percentage of isolates resistant to erythromycin, clindamycin, ciprofloxacin, gentamicin, trimethoprim, and rifampicin (p < 0.001 for each)-resistance characteristics often seen in MRSA. Resistance to benzylpenicillin increased slightly but significantly (p < 0.001); resistance to fusidic acid was stable (p > 0.05); resistance to tetracycline decreased significantly (p < 0.001). INTERPRETATION Among cases of S aureus bacteraemia, the proportion due to MRSA has increased significantly. Bacteraemia due to MRSA has a poor prognosis, especially if not treated with suitable antibiotics. Therefore, these findings are important, especially for management of patients and the development of antibiotic policies.

Prevalence of antibiotic resistance and serotypes in pneumococci in England and Wales: results of observational surveys in 1990 and 1995

Abstract Objective: To assess the prevalence of antibiotic resistance and serotype distribution among pneumococci in England and Wales in 1990 and 1995. Design: Observational surveys in March 1990 and March 1995. During two weeks in each survey period all pneumococci isolated in public health laboratories in England and Wales were collected and assessed for sensitivity to antibiotics and the distribution of serogroups or serotypes. Setting: The network of public health laboratories throughout England and Wales. Subjects: 1127 individual patient isolates of Streptococcus pneumoniae obtained during the two surveys. Main outcome measures: Sensitivity or resistance to a range of antibiotics; serogroup or serotype. Results: The prevalence of intermediate or full resistance to penicillin increased from 1.5% in 1990 to 3.9% in 1995 and resistance to erythromycin increased from 2.8% to 8.6%. About 92% of isolates belonged to serogroups or serotypes included in the currently available pneumococcal vaccine. Conclusion: Resistance to penicillin and erythromycin has increased among pneumococci in England and Wales. Continued surveillance to assess further increases in the prevalence of pneumococcal resistance to antibiotics is essential. Key messages Resistance to cefotaxime or ceftriaxone, which may be the drugs of choice for pneumococcal meningitis caused by penicillin resistant pneumo- cocci, is still fairly rare Roughly 92% of pneumococcal isolates in England and Wales belong to serogroups or serotypes included in the currently available 23 valent vaccine Between 65.1% and 73.9% of pneumococcal isolates from children aged 2 or less belong to sero- groups or serotypes included in the five, seven, or nine valent conjugate vaccines under development for use in children of this age group Continued surveillance of pneumococcal resist- ance to antibiotics is essential if clinicians are to make rational decisions concerning the treatment of pneumococcal infections

Antibiotic resistance among enterococci causing endocarditis in the UK : analysis of isolates referred to a reference laboratory

Enterococci account for 5-15% of cases of bacterial endocarditis.1 They are the most resistant bacteria commonly encountered in this type of infection, which is still associated with a mortality of 20-30%.2 The treatment regimen for enterococcal endocarditis recommended by the British Society for Antimicrobial Chemotherapy and the American Heart Association is a synergistic bactericidal combination of a penicillin or glycopeptide with an aminoglycoside, usually gentamicin or streptomycin. 3 4 However, enterococci can acquire high level resistance to aminoglycosides, which abolishes this synergy.1 Enterococci can also exhibit high level resistance to penicillin or to glycopeptides.1 Our laboratory undertakes testing of bacteria from cases of endocarditis as a routine service; we analysed resistance among isolates from 120 cases of enterococcal endocarditis, received over 27 months. Results of tests for antibiotic susceptibility were analysed for enterococci referred from patients with a clinical diagnosis of endocarditis between January 1995 and March 1998. Isolates exhibiting high …