The role of normal skin in the spread of streptococcal pyoderma

Abstract

SUMMARYThe primary body site of acquisition of group A streptococci was examined prospectively in a population with endemic streptococcal pyoderma. Weekly cultures were obtained during the skin infection season from apparently normal upper respiratory and cutaneous sites (and from skin lesions when present) in 44 children and adults living on the Red Lake Indian Reservation.During the 9-week period of the study 705 of a total of 2305 cultures were positive for group A streptococci. The percentage of positive cultures from the various sites were: throat (20 %); nose (24 %); wrist (32 %); ankle (35 %); back (22 %); and skin lesions (81 %). Group A streptococci were also isolated from fingernail dirt, clothing and bedding as well as from a few household pets and insects.Analysis of serial cultures obtained from the same individuals at weekly intervals suggested that the strains isolated from skin lesions first appeared on normal skin in the 2 weeks preceding the lesion. Spread to the nose and throat followed skin acquisition and/or skin lesions.The high prevalence of group A streptococci on normal skin in the absence as well as the presence of pyoderma, and their appearance on normal skin before recovery from either skin lesions or the upper respiratory tract are consistent with the view that skin acquisition was a primary predisposing factor to pyoderma. Since the literature indicates that group A streptococci are rarely part of the normal skin flora, these findings raise the possibility of unique biological properties of these and perhaps other pyoderma strains, as distinct from other group A streptococci.

Natural history of impetigo

“…In family 1 (see Fig. 4 Studies carried out at the Red Lake Indian Reservation in 1968 revealed that a primary factor in the development of pyoderma was previous acquisition of streptococci on the normal skin (10). The present study confirms these findings with observations at more frequent intervals and extends them to include several other pyoderma strains, including a serotype (M-57) with nephritogenic properties.…”

“…8): 55). This report and the earlier ones from this laboratory (5,10,23) were based on observations at less frequent intervals.…”

“…The Journal of Clinical Investigation Volume 51 November 1972 skin lesions frequently developed later in such children (10).…”

A large outbreak of streptococcal pyoderma in a military training establishment

“…While the Red Lake outbreak in the northern USA showed that cold climates were not inimical to the disease, our and other studies suggested that hot and sweaty skin in physically tired men was particularly susceptible. There is general agreement that streptococci do not penetrate normal intact skin and that a breach of the epidermis by trauma, insect bite or invasion by scabies, mites or other parasites must precede the infection (Dudding et al 1970).…”

Recurrence rate of streptococcal pharyngitis related to hygienic measures

“…Environmental samples were taken with cotton swabs dipped in Todd -Hewitt broth (12). On the pillowcase and floor, an area of 5 cm in diameter was rubbed with the swab.…”