RESISTANCE TO ANTIMICROBIAL AGENTS OF NEISSERIA-GONORRHOEAE ISOLATED AT FLORIANOPOLIS, SANTA-CATARINA

Eighty one Neisseria gonorrhoeae strains were obtained from public and private laboratories, throughout the period from April 1988 to May 19 90. Specimens were plated directly onto Thayer-Martin medium and incub ated at 36-degrees-C under carbon dioxide (5-10%) atmosphere during 24 -48 h. All strains isolated were maintained in a semi-solid medium and stored at room temperature. Sensibility to seven antimicrobial agents was determined by the disk diffusion agar method. This test was perfo rmed on chocolate agar prepared with GC agar base and 1% VX as a suppl ement. The inoculum was produced as a suspension of gonococci in physi ological salt solution prepared at turbidity equivalent to 10(7)-10(8) CFU/ml. A swab was used to inoculate Neisseria over the surface of th e medium in agar plates. The results obtained with these isolates were as follows: 54,32% were resistant to penicillin, 43,21% to ampicillin , 7,41% to cephalothin, 4,94% to erytromycin, 24,69% to streptomycin, 7,41% to gentamicin and 69,14% to tetracycline. Strains that appear re sistant to penicillin inhibition zones smaller than 20 mm were tested for penicillinase production by an acidometric method. This test is ba sed upon a color change showed by a pH indicador when acid is produced from the splitting of ampicillin to penicilloic acid. Sodium ampicill in was added in a buffer-salt solution containing 0,8% potassium chlor ide and 0,01% phenol red to a concentration of 250 mg/ml. Immediately before testing, 20-mu-l of ampicillin (250 mg/ml) were added in 100-mu -l of buffer, previously to the addition of 30-mu-l of a thick suspens ion of gonococci made in the same buffer. Tubes were shaken and incuba ted at 37-degrees-C in a water bath. They were observed at 30 minutes intervals and the definitive reading was made after 3h. The test was c onsidered positive or negative when a yellow or red color appeared, re spectively. Three stains were beta-lactamase producers, representing a n occurrence of 3,7% off penicillinase-producing Neisseria gonorrhoeae in the studied population.