Sulphamethoxazole-Trimethoprim Therapy in Urinary Tract Infection with Reference to its Hematological Effects

The bacteriological and haematological effects of 7 days' treatment with trimethoprim and sulphamethoxazole in a combination of 1 : 5 (13 patients) or 1 : 10 (12 patients) has been investigated in 25 women with significant urinary tract infection. The organisms were Escherichia col***l (23 patients), Klebsiella aerogenes (1 patient) and Proteus mirabilis (1 patient). All 18 primary isolates tested were sensitive to the drug combination in vitro although 3 were resistant to sulphatriad. Twenty-four out of 25 (96%) had sterile urine at 5 days and 80 per cent remained sterile 7 days after therapy. At least 30 per cent recurred within 6 weeks. No significant change was seen in haemoglobin levels, platelet counts or in the percentage of neutrophil polymorphonuclear leucocytes. Sixty-five per cent of patients had low serum folate levels prior to therapy, a finding which may be related to the presence of significant bacteriuria. Following treatment, however, there was a reduction in serum folate levels in both groups which was significant at the 5 per cent level 3 to 7 days after treatment with the 1 : 10 regime and 3 days after treatment with the 1 : 5 regime. It is suggested that it might be advisable in any patient in whom the drug is given on a long-term basis to consider the possibility of haematological side effects.