Trimethoprim versus gentamicin for the prevention of bacteriuria following transrectal biopsy of the prostate--do patients need additional anaerobic cover?

OBJECTIVES: To study the incidence of aerobic and anaerobic bacteriuria in patients undergoing transrectal ultrasound-guided biopsies of the prostate. A comparative assessment of efficacy of trimethoprim with gentamicin for the prevention of bacteriuria following the transrectal biopsy of the prostate. To assess the need for additional prophylaxis against anaerobes for patients undergoing transrectal biopsies of the prostate gland. PATIENTS AND METHODS: In a pilot study during 1995-1997, all the patients undergoing transrectal ultrasound-guided biopsy of the prostate were randomised to receive either trimethoprim or gentamicin prophylaxis prior to the procedure. Midstream urine (MSU) samples were taken just prior to biopsy and 72 h later. A patient questionnaire to determine the symptoms of urinary tract infection (UTI) accompanied the 72-hour MSU request form. Urine samples were cultured aerobically, using a semiquantitative technique if dipstick analysis revealed the presence of blood, pus cell or nitrite. In addition to the routine aerobic culture, post-biopsy samples were also cultured for anaerobes by direct and enrichment methods. Bacteriuria was defined as a pure or mixed growth of 10(5) colony-forming units/ml. Fisher's test of exact probability was used for statistical analysis. RESULTS: 115 patients were available for final analysis. 53 had received gentamicin and 62 trimethoprim. Four patients had pre-existing bacteriuria (3.5%), 3 in the trimethoprim group and 1 in the gentamicin group. Post-operative bacteriuria developed in 5 patients given gentamicin (9.4%) and 1 given trimethoprim (1.6%). This difference was not statistically significant (p = 0.085). Post-procedure bacteriuria was asymptomatic in all but 1 case. Anaerobes were detected in only 5 MSUs (4.3%) post-biopsy. CONCLUSION: Though there was no statistical significant difference in the rates of bacteriuria following administration of trimethoprim and gentamicin, data appear to favour trimethoprim prophylaxis. Further studies are warranted. Transrectal biopsy of the prostate is associated with a low incidence of anaerobic UTI. In view of the very low incidence of anaerobic bacteriuria, routine antibacterial prophylaxis against anaerobes does not appear to be justified.

Mupirocin-resistant Staphylococcus aureus in a specialist school population.

Staphylococcus aureus strains resistant to mupirocin (MIC > 4000 mg l-1) were recovered from children and staff at a school for children with eczema and/or asthma or cystic fibrosis after mupirocin had been used to treat eczematous lesions. At least three distinct strains of S. aureus were involved and resistance was shown to be due in most isolates to a transmissible plasmid. The need for monitoring the extended use of this valuable antibiotic is emphasized.

Rapid differentiation of Streptococcus milleri from other beta-haemolytic group A, C, and G streptococci by simple screening tests.

Eighty five beta-haemolytic Lancefield group A(23), C(22), and G(40) streptococci were tested for sulphonamide sensitivity, ability to degrade beta-D glucuronide (groups C and G) and bacitracin sensitivity (group A). Identification of isolates was initially confirmed by the API 20 STREP system. Zones of beta-haemolysis were too variable for correct Streptococcus milleri identification in 10% of cases. However, only group C and G S. milleri were both sulphonamide-resistant and beta-D glucuronide-negative. Two group A S. milleri strains could have been mis-identified as Streptococcus pyogenes if combined sulphonamide and bacitracin resistance had not been noted. In a busy diagnostic laboratory, screening of beta-haemolytic group A, C, and G streptococci for sulphonamide sensitivity is recommended. Sulphonamide-resistant group A S. pyogenes can be distinguished from S. milleri by bacitracin sensitivity. S. milleri can be rapidly and cheaply differentiated from other sulphonamide-resistant group C and G streptococci by a simple 4 h commercial beta-D glucuronide assay.