Observations on Group-F Streptococci From Human Sources

Abstract

I N comparison with the vast literature concerning group-A streptococci, our knowledge of group-F streptococci is very meagre and there is little published work concerning them. This report documents a series of 22 strains isolated from children and puerperal women during about 4 years and discusses their significance in human disease. MATERIALS AND METHODSPrimary cultures were inoculated on horse-blood agar (BBL Columbia Base; Becton, Dickinson and Co., Canada, Ltd, Mississauga, Ontario) and incubated at 37°C under aerobic and anaerobic conditions for up to 48 h. Haemolytic colonies were examined microscopically and Gram-positive cocci were inoculated into Todd-Hewitt Broth (BBL). These cultures were incubated at 37°C overnight and used for preparing antigen by the method of Rantz and Randall (1955). Lancefield groups were determined by the microprecipitin technique (Lancefield, 1938) with grouping sera purchased from Burroughs Wellcome Ltd, Beckenham, Kent.Sensitivity to bacitracin (Maxted, 1953) was tested with standard bacitracin disks (BBL Tax0 A) and Columbia horse-blood agar. Some strains were inoculated on to aesculin-bileagar slopes (Difco Aesculin Bile Agar, Difco Laboratories, Detroit, USA) or aesculin-agar slopes. RESULTSDuring the period 1971-74 inclusive, some 3500 strains of haemolytic streptococci were subjected to Lancefield grouping. Of these, 22 strains isolated from 22 different patients belonged to Lancefield's group F. Eight of the strains were from peritoneal-cavity swabs taken at operation, in seven for acute appendicitis and in one for ruptured jejunum; five strains were from the vagina of puerperal women; two isolates were from urine, and one from the perineum of one of these patients was presumably related to the infection of the urine. One strain came from an abscess in the neck of a patient who had a history of dental infection, one from an ear swab from a child with cerebrospinal fluid (CSF) leaking from the ear, and one from a maxillary sinus.All group-F organisms were isolated from mixed cultures and since they were selected for further study because they were haemolytic on horse-blood agar, non-haemolytic strains would not have been recognised. Eight strains were quite fastidious anaerobes, two were microaerophilic, and 12 grew readily and were easily recognised on aerobic culture.Colonial morphology was variable. Nine of the strains grew very slowly, producing the classically described pinpoint colonies and attracting attention because of their haemolysis (Long and Bliss, 1934) but 13 strains produced colonies that were easily visible after overnight incubation. One strain was isolated repeatedly in pure culture from the urine and perineum of a patient who had undergone a renal transplant. Several strains, including this one, grew so slowly in Todd-Hewitt broth that incubation for 5-7 days was required before growth was adequate for the production of grouping antigen. All strains gave clear precipitin

Infection with minute-colony-forming beta-haemolytic streptococci.

“…Although isolated 'minute' strains of group F and G from the throat in 6-8 % of normal subjects and Hare (1935) stated that strains of group F occurred mainly in the nasopharynx, more recent work does not support their observations on the importance of this site. Haemolytic strains occurred in only 41 (0.6%) of an estimated 7000 throat swabs examined in the present study, and Wort (1975) reported an isolation rate of only 0 04 % of group F strains from similar material. Guthof (1956) was unable to demonstrate non-haemolytic Strep.…”

Streptococci and aerococci associated with systemic infection in man

“…Ottens and Winkler (1962) found many strains of S. milleri in the dental root-canal, and we found them often on the surface of the teeth and on sutures removed after dental operations (Phillips et al, 1976). The anatomical distribution of the lesions in our series suggests that the source of a considerable number of them was in the abdomen, a conclusion reached by Wort (1975) from a study of group-F infections. Studies of the distribution of S. milleri in the gut have not been made, but Rogers (1957) isolated group-F streptococci from 11 % of acutely inflamed appendices.…”

“…It often grows poorly or not at all in the absence of CO,; many of the strains submitted to us had initially been described as " micro-aerophilic " or " anaerobic " streptococci. Meningitis, peritonitis, pleural empyema and bacteriaemia caused by group-F streptococci (Rantz, 1942;Wheeler and Foley, 1943 ;Foley, 1947;Koepke, 1965;Wort, 1975) or by non-haemolytic, bacitracinresistant group-A streptococci (Bannatyne and Robson, 1974) have been described; these organisms are very likely to have been S. milleri.…”

Streptococcus anginosus ("Streptococcus milleri"): the unrecognized pathogen

“…Cultures of the oral cavity (50), throat (8,47), feces (71,75), and vagina (80) have all yielded "S. milleri" strains. Poole and Wilson (62) noted that a majority of isolates from teeth were hemolytic, but fecal and vaginal strains tended to be nonhemolytic.…”