M C J Wale

Bacteraemia and antibiotic resistance of its pathogens reported in England and Wales between 1990 and 1998: trend analysis

Abstract Objectives: Determination of causes, trends, and antibiotic resistance in reports of bacterial pathogens isolated from blood in England and Wales from 1990 to 1998. Design: Description of bacterial isolates from blood, judged to be clinically significant by microbiology staff, reported to the Communicable Disease Surveillance Centre. Setting: Microbiology laboratories in England and Wales. Subjects: Patients yielding clinically significant isolates from blood. Main outcome measures: Frequency and Poisson regression analyses for trend of reported causes of bacteraemia and proportions of antibiotic resistant isolates. Results: There was an upward trend in total numbers of reports of bacteraemia. The five most cited organisms accounted for over 60% of reports each year. There was a substantial increase in the proportion of reports of Staphylococcus aureus resistant to methicillin, Streptococcus pneumoniae resistance to penicillin and erythromycin, and Enterococcus faecalis and Enterococcus faecium resistance to vancomycin. No increase was seen in resistance of Escherichia coli to gentamicin. Conclusions: Reports from laboratories provide valuable information on trends and antibiotic resistance in bacteraemia and show a worrying increase in resistance to important antibiotics.

Changing carriage rate of Neisseria meningitidis among university students during the first week of term: cross sectional study.

Abstract Objective: To determine the rates of, and risk factors for, meningococcal carriage and acquisition among university students. Design: Repeated cross sectional study. Participants: 2507 students in their first year at university. Main outcome measures: Prevalence of carriage of meningococci and risk factors for carriage and acquisition of meningococci. Results: Carriage rates for meningoccoci increased rapidly in the first week of term from 6.9% on day 1, to 11.2% on day 2, to 19.0% on day 3, and to 23.1% on day 4. The average carriage rate during the first week of term in October among students living in catered halls was 13.9%. By November this had risen to 31.0% and in December it had reached 34.2%. Independent associations for acquisition of meningococci in the autumn term were frequency of visits to a hall bar (5-7 visits: odds ratio 2.7, 95% confidence interval 1.5 to 4.8), active smoking (1.6, 1.0 to 2.6), being male (1.6, 1.2 to 2.2), visits to night clubs (1.3, 1.0 to 1.6), and intimate kissing (1.4, 1.0 to 1.8). Lower rates of acquisition were found in female only halls (0.5, 0.3 to 0.9). The most commonly acquired meningococcal strain was C2a P1.5 (P1.2), which has been implicated in clusters of invasive meningococcal disease at other UK universities. Conclusions: Carriage rates of meningococci among university students increase rapidly in the first week of term, with further increases during the term. The rapid rate of acquisition may explain the increased risk of invasive meningococcal disease and the timing of cases and outbreaks in university students.

Surveillance of antimicrobial resistance: Centralised surveys to validate routine data offer a practical approach

Antibiotic resistance is increasing and significant public health problems are feared. Actions to mitigate the problem include development of new antimicrobials, better infection control, and greater conservation of existing agents. One pressing problem is the paucity of data to measure the impact of resistance on public health or the effect of interventions to prevent its emergence and spread. Moreover, other factors besides clinical prescribing may drive resistance — failure of infection control; institutionalisation of care for the very young and elderly; changing population age structures; agricultural use of antibiotics; and the spread of strains that are effective colonists and which, coincidentally, are resistant.1 Better surveillance of resistance is needed to understand this interplay as well as to advise on empirical therapy. 2 3 Once relations between use and resistance have been established surveillance data then can serve as “information for action” for initiatives to decrease unnecessary prescribing and prolong the usefulness of existing antibiotics. Establishing such surveillance presents several problems. 2 3 It is easiest to count resistance rates of bacteria received at laboratories, but these organisms form a biased sample because (a) laboratory requesting varies greatly among clinicians; (b) some diseases (such as chronic obstructive airways disease) are more likely to generate laboratory specimens than others (such as pneumonia); (c) some age groups, particularly the elderly, are more likely to have specimens taken than others; and (d) primary care specimens are usually sent only from patients who have failed to respond to empirical treatment or who have comorbidities. Ideally resistance should have a clinical denominator (number of infected patients) not a laboratory one (number of isolates), but this is not easy except in uncommon diseases such …

Adverse medical events in British service personnel following anthrax vaccination.

The safety of the UK anthrax vaccine in British service personnel was evaluated by a retrospective cohort study of randomly selected personnel from five Royal Air Force bases by investigating adverse medical events and consultation rates for a period before and after vaccination. Vaccination acceptance rate varied from 27 to 89% (P=0.0001). In the vaccinated cohort 11.1% (n=368) reported side-effects. The number of consultations in the year prior to vaccination (P=0.04) and RAF base (P=0.0085) were associated with side-effects. Only the RAF base remained a statistically significant factor (P=0.007) after adjusting for other factors. The anthrax vaccine resulted in mild side-effects in 11%, and no serious side-effects were observed. Acceptors of vaccine did not have significantly more medical consultations following vaccination than their unvaccinated counterparts.

Turbidimetric response ofStaphylococcus aureus andEnterococcus faecalis to daptomycin

The response to daptomycin of three strains ofStaphylococcus aureus (one of which was methicillin-resistant) and a strain ofEnterococcus faecalis was investigated by continuous turbidimetric monitoring. Daptomycin caused partial inhibition of bacterial growth at concentrations well below those suppressing growth overnight. The activity of the drug was more than 200-fold greater in the presence of a physiological concentration of calcium (2.5 mmol/l) than in its absence. Variants present in cultures inhibited by daptomycin were shown to exhibit decreased susceptibility to the drug and the susceptibility declined further on repeat exposure; however, there was a slow but incomplete reversion to susceptibility on sequential subculture in drug-free broth. Resistance was difficult to induce when the concentration of calcium in the broth exceeded 2.5 mmol/l.