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M Tirado

Publications and source records attributed to M Tirado.

29 records · Page 2Linked to original sources
PubMed1983

Plasmid-determined beta-lactamases identified in a group of 204 ampicillin-resistant Enterobacteriaceae.

Information is presented on the plasmid-determined beta-lactamases identified in 204 strains of ampicillin-resistant Enterobacteriaceae. The type most frequently identified was TEM-1 (in 85.3% of the strains), followed by SHV-1 (14.70%). Two types of plasmid-determined beta-lactamase were identified in 20 strains; in 18 of them one of the two was TEM-1 and in 13, SHV-1 (the TEM-1 + SHV-1 combination was observed in 12 strains). In the 41 Klebsiella strains the most frequently identified enzyme was SHV-1 (in 28 of the strains) and the proportion of strains with two plasmid-determined beta-lactamases was higher than in the other species studied.

Ampicillin↗
PubMed1982

Complementary activity of mezlocillin and the combination of amoxicillin with clavulanic acid on Enterobacteriaceae.

The MICs of amoxicillin, mezlocillin and BRL 25,000, a combination of two parts amoxicillin and one part clavulanic acid (2AM + 1CA), were measured for 331 Enterobacteriaceae strains which produced beta-lactamases as demonstrated by nitrocefin. The MIC values for mezlocillin and the combination 2AM + 1CA were very similar for the total number of the strains investigated. When investigated separately according to the bacterial species, three different sensitivity groups were established for the above-mentioned preparations: 1) species with the same or similar sensitivity to mezlocillin and 2AM + 1CA (Escherichia coli and Shigella spp., amoxicillin-resistant strains); 2) species which were more sensitive to mezlocillin than to the combination 2AM + 1CA (Citrobacter spp., Enterobacter cloacae, Serratia spp. and indole-positive Proteus as well as strains of E. coli and Shigella spp. which produce a cephalosporinase and are sensitive to amoxicillin); 3) species which are more sensitive to 2AM + 1CA than to mezlocillin (amoxicillin-resistant Salmonella spp., Proteus mirabilis and Klebsiella pneumoniae). This complementary activity of mezlocillin and 2AM + 1CA against Enterobacteriaceae depended on the beta-lactamases produced.

Amoxicillin↗
PubMed1981

[Cefsulodin, a new antibiotic of the group of cephalosporins: its action on Pseudomonas aeruginosa (author's transl)].

Cefsulodin is a new second generation cephalosporin with a narrow antibacterial spectrum. Its main use is in the treatment of Pseudomonas aeruginosa infections. It is resistant to the action of the beta-lactamases of gram negative bacilli, especially to that of the cephalosporinases. We have studied 170 strains of P. aeruginosa and 10 of other species of Pseudomonas, determining the MIC by the serial dilution test in solid medium and the sensitivity by the agar diffusion test. With 8 microgram/ml, a concentration which is accepted as a limit of sensitivity from the therapeutic point of view, 90% of the P. aeruginosa strains studied are inhibited; the MIC50 is obtained with 2 microgram/ml. Within the strains considered sensitive (MIC less than 8 microgram/ml) there is a marked dispersion of the zone diameters corresponding to each of the values of MIC. This behavior limits the value of the regression line. We have also studied the MIC of carbenicillin for nearly all the strains and we have also studied the MIC of carbenicillin for nearly all the strains and we have found that 86.58% are sensitive to both preparations, 4.96% are sensitive to cefsulodin and resistant to carbenicillin, 4.02% resistant to cefsulodin and sensitive to carbenicillin and 4.69% are resistant to both preparations. From the clinical point of view the number of strains sensitive (or resistant) is similar with both substances but cefsulodin is in absolute values from 8 to 128 times more day active than carbenicillin. Cefsulodin is administered by a parenteral route and is eliminated by the urine in active form. The recommended therapeutic dose for the treatment of systemic infections is 2 g daily IV. This dose may be increased if it is considered advisable. There is good local tolerance (IM and IV), it is only slightly toxic, hardly alters the intestinal flora and may be used at all ages, in patients with immunological alterations and in patients with an altered renal function.

Carbenicillin↗
PubMed1980

[Studies on antibacterial activity of cephotaxime (HR 756), a new antibiotic of the cephalosporin group (author's transl)].

Cephotaxime (HR 756) is a new cephalosporin antibiotic of wide spectrum and extraordinary activity, suitable for parenteral administration. It is highly resistant to the beta-lactamases of Gram negative bacilli, being thus especially active against microorganisms such as indole-positive Proteus, Serratia marcencens, and others usually resistant to most beta-lactamic antibiotics because of their ability to produce beta-lactamases of high activity. The sensitivity of 355 different bacterial strains to cephotaxime has been determined by the disc method, along with the minimal inhibitory concentration (MIC) of the drug to the same strains, and regression lines have been constructed. The extraordinary activity of cephotaxime against Enterobacteriaceae, Vibrio Cholerae, Haemophilus, and Neisseria meningitidis is noteworthy. Of the 220 strains of Enterobacteriaceae studied, 55% produced beta-lactamase. The MIC of cephotaxime for beta-lactamase forming strains was similar to that for non-forming strains.

Cefotaxime↗
PubMedDate not supplied

Activity of ciprofloxacin (BAYo 9867) against Pseudomonas aeruginosa and ampicillin-resistant Enterobacteriaceae.

We studied the in vitro activity of ciprofloxacin against 570 strains of ampicillin-resistant Enterobacteriaceae and 286 Pseudomonas aeruginosa strains. 95.26% of the Enterobacteriaceae and 53.45% of the P. aeruginosa were inhibited by 0.1 mg/l of ciprofloxacin. 2 mg/l of ciprofloxacin inhibited all of the Enterobacteriaceae strains and 4 mg/l all of the P. aeruginosa. We compared the activity of ciprofloxacin with that of temocillin in the Enterobacteriaceae strains. In the P. aeruginosa strains, classified according to their susceptibility to carbenicillin and gentamicin, we compared the activity of ciprofloxacin with that of ceftazidime. In the strains studied, the in vitro activity of ciprofloxacin is superior to that of temocillin against the Enterobacteriaceae and to that of ceftazidime against the P. aeruginosa strains.

Ampicillin↗
PubMedDate not supplied

[Resistance of Haemophilus influenzae and Haemophilus parainfluenzae to beta-lactam antibiotics. Characterization of the beta-lactamases].

We have studied the susceptibility to ampicillin and the characteristics of the beta-lactamase activity of the 169 Haemophilus spp. strains (128 H. influenzae, 40 H. parainfluenzae and one H. paraphrophilus) isolated during 12 months, years 1988-1989, in the Hospital del Mar clinical microbiology laboratory. Our objective was to know in the strains of our center the frequency of those resistant or slightly susceptible to ampicillin, the role of beta-lactamases in the loss of susceptibility and the type of enzymes involved. Susceptibility was studied by diffusion for all the antibiotics tested and also confirmed by dilution for ampicillin and other beta-lactam antibiotics. Beta-lactamase production was identified by nitrocefin hydrolysis. The isoelectric point of the beta-lactamase and the identification of their types were determined by analytic isoelectric focusing. The presence of the codifying gene of the TEM-1 enzyme was studied by hybridization with a TEM-1 probe. Of the H. influenzae strains 35 were ampicillin resistant, one moderately susceptible and of the H. parainfluenzae strains six were resistant and two moderately susceptible; all were susceptible to the combination of amoxicillin/clavulanic acid. The ampicillin-resistant strains were beta-lactamase producers. In 40 strains, by isoelectric focusing, the type TEM-1 was identified and the hybridization was positive; in one H. parainfluenzae strain a beta-lactamase of pl 5.8 was observed and the hybridization with TEM-1 probe was negative. The three strains moderately susceptible to ampicillin did not produce beta-lactamase.

Adult↗
PubMedDate not supplied

A clinical comparison of two formulations of tobramycin 0.3% eyedrops in the treatment of acute bacterial conjunctivitis.

PURPOSE: To compare the safety and efficacy of a new enhanced viscosity ophthalmic formulation of tobramycin, given twice daily (BID), with the existing four times daily (QID) treatment regimen in patients with acute bacterial conjunctivitis. METHODS: This was a 12-day, multicenter, observer-masked, randomized, parallel group study. Patients received one drop of tobramycin 0.3% (3 mg/mL) enhanced viscosity ophthalmic solution BID or tobramycin 0.3% (3 mg/mL) ophthalmic solution QID in the affected eyes for 7 days. The primary efficacy variable was the percentage of patients with sustained cure/presumed bacterial eradication based on clinical judgment at the test-of-cure visit (Day 12). Pretherapy bacterial isolates were obtained and tested for susceptibility to tobramycin by determination of minimum inhibitory concentrations (MIC). RESULTS: A total of 276 patients were enrolled in the study and 203 of these were culture positive and attended all follow-up examinations. In this group, 98% of those treated with tobramycin enhanced viscosity ophthalmic solution and 99% of those treated with tobramycin 0.3% ophthalmic solution were categorized as having sustained cure/presumed eradication at the test-of-cure visit (p = 0.6037). Reported adverse events were not serious, mild to moderate in severity, and generally did not prevent continuation in the study. Several pre treatment pathogens demonstrated tobramycin resistance (MIC > 4 mg/mL). However, therapy with both treatments was effective in the majority of the cases. CONCLUSIONS: Tobramycin enhanced viscosity ophthalmic solution is well tolerated and has equivalent efficacy to the established treatment regimen with a simplified posology. The formulation provides an alternative therapy for acute bacterial conjunctivitis that should improve patient compliance and satisfaction.

Acute Disease↗
PubMedDate not supplied

[Detection of hyperproduction of chromosomal beta-lactamase in strains of Escherichia coli, Enterobacter cloacae and Pseudomonas aeruginosa].

In order to show up the hyperproduction of chromosomic beta-lactamases in strains of Enterobacteriaceae and Pseudomonas aeruginosa we have tested a variant of a technique proposed by Medeiros et al. It is a qualitative technique and, the modification introduced allows errors of interpretation to be avoided, when the strain is a producer of plasmidic beta-lactamase. It is based on evaluating the amount of beta-lactamase in a culture, measured in time taken for the hydrolysis of nitrocefin, with or without the addition of clavulanic acid. We present the results obtained in 526 selected strains: 271 E. coli, 116 E. cloacae and 139 P. aeruginosa. One hundred and twenty for strains hydrolyzed the nitrocefin in the absence of clavulanic acid within 60 seconds. Only 52 (41.94%) of these strains did it when clavulanic acid was present; all of them have been qualified as hyperproducers according to susceptibility to beta-lactam antibiotics and the study and identification of the beta-lactamases by analytic isoelectrofocusing. The hydrolysis was evident before the 15 seconds in the 80% of hyperproducer strains. No false positive results were observed.

Cephalosporins↗