Beta-haemolytic streptococci isolated from acute sore-throat patients: Cause or coincidence? A case-control study in general practice

As beta-haemolytic streptococci can he cultured in people with and in those without a sore throat, a case-control study was set up in 43 family practi ces in The Netherlands. The association was tested between the number of co lony counts, specific T/M types and exotosin genes and an acute sore throat . Duplicate throat swabs mere taken from 663 sore-throat patients, selected by clinical criteria, and From 694 healthy controls. They mere cultured fo r beta-haemolytic streptococci by combining several updated laboratory meth ods, Approximately 40% of the controls and 80% of the patients had beta-hae molytic streptococci-positive cultures, When focusing on cultures with high colony counts, not only group A (46%), but also non-group A streptococci ( 20%), predominated significantly in adult patients compared with controls. No T/M or exotoxin gene type was significantly more prevalent in patients t han in controls. Thus, semiquantitative analysis, but not T/M and exotoxin gene typing, showed an association between beta-haemolytic streptococci and active disease. Groups A, C and G streptococci were found to be potentiall y pathogenic in adult sore-throat patients, and should be included in the d iscussion on the use of rapid antigen detection tests and penicillin treatm ent in primary care.