1The Association of Clinical Pathologists: 89th general meeting 1966 cultures of meningococci isolated from patients in different areas of England and Northern Ireland

1966 cultures of meningococci isolated from patients in different areas of England and Northern Ireland have been sent to the Manchester Public Health Laboratory for serotyping and for testing for sensitivity to sulphonamides. From 1966 to the end of April 1972, we have typed 342 cultures isolated from blood or CSF: 27 strains were group A (8 %), 185 group B (54 %), 113 group C (33 %), one strain each group X and Y, and 15 were untypable (4%). The majority of untypable strains (13/15) were received before 1970 and had been stored for long periods before typing. During the same period 370 cultures were tested for sensitivity to sodium sulphadiazine. The majority of cultures 319 (86%) were inhibited by 0 16 mg% sodium sulphadiazine, and a further 18 (5 %) by 0-32 mg %. Thirty-three strains (9%) had a minimal inhibitory concentration of 0 64 mg% or greater, and these we have classed as resistant; 12 of these (3%) had a minimal inhibitory concentration of 0 64-1 mg%, and 21 (6%) a minimal inhibitory concentration of 5 mg% or more. The proportion of resistant strains isolated recently appears to be increasing-22% of those isolated in the first four months of 1972 compared with 7% of those in 1971. Resistant strains were isolated from different areas of England and Northern Ireland. The proportion of resistant strains amongst different serotypes varies-6 % of group B, 8% of group C, and 44% of group A strains. These findings and the report of sulphonamide-resistant strains in Scotland (Fallon, 1971) clearly indicate that sulphonamides alone cannot be relied upon for the treatment of meningococcal infection in this country, and the efficacy of sulphonamides for chemoprophylaxis may be affected by the presence of sulphonamide-resistant strains.