Multiple antimicrobial resistance in pneumococci was detected in Johannesburg in July, 1977, and prompted an investigation of the prevalence of resistant strains in two hospitals. Carriers of Types 6A and 19A penicillin-resistant pneumococci, resistant to antibiotic concentrations ranging between 0.12 and 4 microgram per milliliter were found in 29 per cent of 543 pediatric patients and 2 per cent of 434 hospital staff members. Multiply resistant Type 19A strains, resistant to beta-lactam antibiotics, erythromycin, clindamycin, tetracycline and chloramphenicol, were isolated from 128 carriers, and were responsible for bacteremia in four patients. Isolates from 40 other carriers were resistant to penicillin alone or to penicillin and chloramphenicol or to penicillin, chloramphenicol and tetracycline. Pneumococci can be screened for penicillin resistance with a modified Kirby--Bauer technic; the strains with zones of less than 35 mm around 6-microgram penicillin disks or less than 25 mm around 5-microgram methicillin disks should be tested for sensitivity to penicillin by measurements of minimum inhibitory concentration.

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A derivative of quinolinecarboxylic acid, ciprofloxacin (BAY o 9867) was found to be an effective bactericidal agent against Pseudomonas aeruginosa and Escherichia coli. A bactericidal effect was achieved immediately after the addition of ciprofloxacin. At a concentration of 0.5 ,ug/ml, culture viability was reduced from 5 x 10 to about S x 103 CFU/ml within 15 min, and at 0.1 ,ug/ml, a >10-fold reduction in viability resulted during the first hour after exposure. This bactericidal activity observed during the lag phase in Mueller-Hinton broth was also demonstrated in a nongrowing system. The antibiotics used in comparative studies, i.e., tobramycin, aztreonam, cefotaxime, and azlocillin, did not show this initial bactericidal activity, and ciprofloxacin prevented culture regrowth at lower concentrations. Staphylococcus aureus was not as susceptible to ciprofloxacin; killing occurred at a concentration of 0.5 ,Ig/ml only after the onset of exponential growth in the control culture. Synergistic interactions were observed wtih ciprofloxacin in combination with tobramycin and azlociilin against P. aeruginosa and with cefotaxime and tobramycin against E. coli.

In an analysis of 4766 consecutive strains of Streptococcus pneumoniae isolated from cultures of blood from 1979 to 1986 and of 1157 isolates from cerebrospinal fluid (CSF), resistance was found in 380 (8%) of blood and 107 (9.2%) of CSF isolates to one or more of the following antibiotics: penicillin, tetracycline, erythromycin, clindamycin, rifampin, and chloramphenicol. Resistance increased from 3.8% to 14.1% among isolates from blood and from 6.8% to 14.1% among CSF isolates during this period. Comparing 1979-1982 with 1983-1986, we found that significant increases (P less than .01) have occurred in penicillin resistance alone, rifampin resistance alone, and in strains showing multiple resistance. Resistance was found in 15 different serogroups and/or serotypes, although 92.2% of resistant strains belonged to serogroups 6 or 19 or to serotype 14. Of the serogrouped or serotyped strains, 97.4% are represented in the 23-valent vaccine by a vaccine or vaccine-related strain.

A total of 19 of 20 (95%) strains of Aeromonas hydrophila biovar hydrophila and 16 of 17 (94%) strains of Aeromonas sobria isolated from a variety of clinical and environmental sources were found to be enterotoxin positive. Only 2 of 18 (11%) A. hydrophila biovar anaerogenes and 2 of 13 (15%) unidentified Aeromonas strains from a similar variety of sources produced enterotoxin. No association was apparent between the source of isolation, in particular diarrheal stools, and enterotoxigenicity; 41% of the isolates from diarrheal stools were enterotoxin negative. A strong correlation was noted between ability to produce enterotoxin and positive results in six characters: lysine decarboxylase and Voges-Proskauer reactions, production of gas from glucose, gluconate oxidation, xanthine hydrolysis, and hemolysis of human erythrocytes. In the majority of cases (35 of 39 strains), enterotoxigenicity was detected using cell-free filtrates of brain heart infusion broth cultures grown at 36°C for 15 h; however, the other four positive isolates were detected after growth in the same broth at 30°C or in Casamino Acids-yeast extract broth at 30 or 37°C. It is recommended that for enterotoxin tests, strains should be grown in both media at both temperatures. The infant mouse test was found to be a simple and reliable method for detection of the enterotoxin. The toxin proved to be heat labile and not neutralized by cholera antitoxin. Aeromonads are ubiquitous waterborne bacteria belonging to the Vibrionaceae. The taxonomy of Aeromonas spp. has been in a state of flux for some years, and only now is it becoming better understood. At present, the most frequently used classification of motile Aeromonas spp. is that of Popoff and Véron (29), who divided them into Aeromonas hydrophila biovar hydrophila, A. hydrophila biovar anaerogenes, and a new species, Aeromonas sobria. More recently, it has been proposed that A. hydrophila biovar anaerogenes should be renamed Aeromonas caviae (28), but this remains to be validated. Even now, many laboratories are unable to distinguish these species readily, and nonspecific references to A. hydrophila in reports until very recently can be interpreted as encompassing both biovars of A. hydrophila (sensu strictu) and A. sobria. These species, usually under the name A. hydrophila, have been isolated frequently from soil, foods, and a variety of animals, mostly those associated with water, such as fish, reptiles, and amphibians; in fact, these species have long been recognized as pathogenic agents causing hemorrhagic septicemias in these types of cold-blooded animals (12, 13, 17, 23). Their ability to cause opportunistic infections in compromised human hosts has been accepted for some time, and reports of various types of A. hydrophila infections, particularly in swimming-related injuries, in previously healthy persons are increasing. References to such reports are listed by other authors (6, 17, 32). Several investigators have reported the isolation of A.