[Frequency of colicin and hemolysins in Escherichia coli isolated from pregnant patients with urinary tract infection, symptomatic and asymptomatic]. / Frecuencia de colicina y hemolisinas en Escherichia coli aisladas de pacientes embarazadas con infección de vías urinarias, sintomática y asintomática.

Colicin production was studied among 137 Escherichia coli strains isolated from pregnant patients with symptomatic or asymptomatic, urinary tract infection (IVU). The observed colicinogeny frequency was 72.92% (n = 96), among the symptomatic patients and 29.26% (n = 41) among the asymptomatic group. The most frequently identified colicins from symptomatic patients were: V (23.9%), A (18.7%) and E1 (17.7%) and within the patients with asymptomatic IVU the most frequently observed colicins were A (9.7%), E1 (17.0%) y V (2.4%). The major frequency of colicin V among the E. coli strains isolated from the symptomatic group against the asymptomatic one, was statistical significant (p > or = 0.025). The results on the observed frequencies of colicins E1 and A were not statistical significant. Among the 137 studied E. coli strains, 37.2% were hemolytic. 83.3% of the colicin V producing strains (n = 24) were hemolytic, among the strains producing other colicin different than colicin V 34% (n = 58) were hemolytic and 12.0% of non colicinogenic strains were hemolytic. These results were statistical significant (p > 0.05). The present data, suggest that colicins production is an important pathogenicity factor among the E. coli strains, specially for those strains producing colicin V. The observed association among hemolysin and colicin V production may be an interesting pathogenicity factor which suggests an increasing ability of uropathogenic strains to produce symptomatic urinary tract infections.

Antimutagenesis of beta-carotene to mutations induced by quinolone on Salmonella typhimurium.

BACKGROUND: Quinolone-induced mutagenesis in the Salmonella typhimurium hisG48 strains suggests that these antibiotics are oxygen free radical generators. The use of beta-carotene as antioxidant was evaluated as an alternative to reduce oxidative cell damage in patients who need therapy with nalidixic acid, norfloxacin, or pipemidic acid. The studied beta-carotene (30%), used by pharmaceutical laboratories as dietary complements, was not toxic or mutagenic for the S. typhimurium TA102 strain at a dose equivalent to 1,500 I.U. At the studied concentrations, the evaluated antimutagen did not modify the minimum inhibitory concentration of nalidixic acid, norfloxacin, or pipemidic acid against uropathogenic Escherichia coli strains. METHODS: The mutagenic effect of nalidixic acid and norfloxacin against hisG48 strains was inhibited with 1500 I.U. of beta-carotene. The antimutagenic effect of beta-carotene against mutations induced by pipemidic acid was observed even with 150 I.U. of beta-carotene. The antimutagenic effect against mutations induced on S. typhimurium TA102 or TA104 strains was observed only when the aroclor 1254 rat-induced liver S9 mixture was used. RESULTS: This mutagenic effect was detected only when the strains were exposed to quinolones and the beta-carotene simultaneously with the S9 mixture, suggesting that quinolones induce oxygen free radicals that may be scavenged by beta-carotene. CONCLUSIONS: The antimutagenic effect of this vitamin A precursor is probably due to the active molecule of vitamin A, a desmutagen with the ability of radical capture. A diet rich in beta-carotene or vitamin A could be a good alternative to reduce genotoxic risk to patients being treated with quinolone.

Genotoxic evaluation of norfloxacin and pipemidic acid with the Escherichia coli Pol A-/Pol A+ and the ames test.

BACKGROUND: Genotoxicity of antibiotics has not been well evaluated, and there is not much information on the genetic risk of quinolone drugs, even though they are widely used as alternative choice drugs in urinary infections. METHODS: Pipemidic acid and norfloxacin were tested for their capacity to induce point mutations using the Ames test and DNA damage on Escherichia coli PolA-/PolA+. RESULTS: At non-toxic doses, all of the drugs studied were negative on the E. coli PolA-/PolA+ test with or without in vitro metabolic activation with induced arochlor 1254 rat liver (S9). They did not produce frameshift mutations in TA98, or base-pair substitutions in S. typhimurium hisG46 strains TA100, or UTH8414. Norfloxacin and its induced metabolites in vitro with S9 rat liver were mutagenic to hisG48 strains TA102 and TA104, both of which detect oxidative chemicals. Pipemidic acid induced mutations in S. typhimurium hisG48 strains only when they had an efficient DNA excision repair system. CONCLUSIONS: These results suggest that the risk of oxygen-free radical generation from quinolones should be considered.

[The resistance and serotyping of 83 strains of Streptococcus pneumoniae isolated from asymptomatic carriers and ill children]. / Resistencia y serotipificación de 83 cepas de Streptococcus pneumoniae aisladas de niños portadores asintomáticos y enfermos.

Eight-three isolates of Streptococcus pneumoniae obtained from children hospitalized with several infections in Mexico City and Cuernavaca, and from healthy children attending a day-care center in Cuernavaca, from January to September 1992, were screened for antimicrobial resistance patterns by in vitro susceptibility testing against antimicrobial agents of potential use in the treatment of diseases caused by S. pneumoniae (39 infected patients and 44 from healthy children). 21.6% of strains were resistant to penicillin, 52% of the strains were multiresistant without a commun pattern. Children attending a day-care center had a higher rate of S. pneumoniae strains resistant to one or more antimicrobial than hospitalized children. Serotypes or serogroups 6, 23F, 14 and 19 were most prevalent. There are evidence that strain 23F has an intercontinental link, this strain is associated with disseminated diseases and multiresistance to antimicrobials. The results indicate that changes can occur in the susceptibility of S. pneumoniae and that selective susceptibility testing and epidemiologic studies in hospitalized patients and children in day-care centers are necessary.