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Streptolysin S exists in a cell-bound form and as an extracellular complex between a nonspecific carrier (serum, serum albumin, ribonucleic acid [RNA], Triton, Tween) and a hemolytic moiety (probably a peptide) synthesized by streptococci. Although all the forms of streptolysin S, at 100 hemolytic units, killed mouse leukocyte monolayers, the time needed to kill 100% of the cells varied with the different streptolysin S preparations. Whereas 30 min was sufficient for the cell-bound hemolysin to kill all of the cells, 60 and 180 min were required when RNA streptolysin S and serum streptolysin S, respectively, were employed. Addition of 10% mouse serum to RNA streptolysin S or to cell-bound hemolysin delayed the killing of the leukocytes. The delayed killing observed with serum and albumin hemolysins is probably due to competition for the hemolytic moiety between the carrier molecules and target sites (phospholipids) upon the leukocyte membrane. Serum streptolysin S must

A food-borne outbreak of sore throat caused by Lancefield group G beta-haemolytic streptococci and involving 50 persons occurred in May 1983 in an Israeli military camp. All of the patients available for clinical examination had sore throat and difficulty in swallowing. Exudative tonsillitis occurred in 46% of the patients and the body temperature was above 37.5 degrees C in 81%. The pattern of attack was uniform over the base and 37 became ill during the night and morning of the 5 May. Thirty-two (84%) of the throat cultures taken from 37 patients grew group G beta-haemolytic streptococci. Eight of 29 contacts were positive for group G beta-haemolytic streptococci and 6 of the 28 foodhandlers examined had positive cultures of the same group. The organism was also isolated from one food sample. The epidemiological and laboratory investigations indicated that a food handler, a convalescent carrier of group G streptococci, might have been the source of infection. Assumptions on the potential of non-group A streptococci to cause epidemics are discussed.

A total of 229 clinical isolates of Streptococcus pneumoniae recovered from 225 patients were serotyped and tested for susceptibility to penicillin G, ampicillin, mezlocillin, cefazolin, erythromycin, clindamycin, chloramphenicol, and sulfamethoxazole-trimethoprim. Of all the isolates, 48 Penicillin resistance in pneumococci has been reported in many parts of the world during the last few years, and the problem has been recently reviewed (13). The degree of penicillin resistance reported for pneumococci is variable, but even with strains having intermediate resistance to penicillin (PIR strains), unsuccessful treatment, especially of meningitis, has been reported (1,3,4,7,11). Information about serotypes of penicillin-resistant (PR) pneumococcal strains is needed in order to design an epidemiological policy for control measures (13) and because the effectiveness of the 14-valent pneumococcal vaccine to prevent the development of systemic pneumococcal disease and reduce the transmission of PR strains (8) depends on the inclusion of appropriate serotypes. In addition, studies on the susceptibility of PR strains to other antimicrobial agents are important to detect multiply resistant organisms and to assess alternative therapeutic approaches (13).The purpose of this work was twofold: (i) to investigate the susceptibility of clinically significant isolates of Streptococcus pneumoniae to penicillin G and to other antimicrobial agents used in the treatment pf pneumococcal infections, and (ii) to establish the serotype distribution of the PR strains. plied for each isolate included the age, sex, and ethnic origin of the patient, source of isolation, and mortality. Typing was performed with sera supplied by the Statens Seruminstitut, Copenhagen, Denmark. The bacteria were lyophilized and stored at 4°C until tested. Confirmation and final typing were performed at the Statens Seruminstitut by Henrichsen. Three different serotypes in one patient and two different serotypes in each of two additional patients were isolated from ear pus sampled on different dates. Susceptibility testing. Since one strain was isolated from both blood and cerebrospinal fluid cultures of the same patient, 229 isolates were tested for susceptibility to penicillin G, ampicilLin, cefazolin, mezlocillin, erythromycin, clindamycin, chloramphenicol, and sulfamethoxazole-trimethoprim by the agar dilution method (16) with Iso-Sensitest agar (Oxoid Ltd., London) supplemented with 5% defibrinated human blood. All the antibacterial media were freshly prepared and used within 48 h of preparation. The test organisms were grown overnight in Todd-Hewitt broth (Difco Laboratories, Detroit, Mich.) at 37°C. The cultures were adequately diluted to give a final inoculum of about 105 CFU in each spot with a multipoint inoculator (400 U; Mast). Controls were prepared with Staph-

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