Molecular epidemiology of drug-resistant Salmonella Typhimurium in Spain.

One hundred and forty-seven Salmonella serotype Typhimurium strains isolated in three provinces in the midwest of Spain were studied. Of these, 93.6% were drug resistant. There were two predominant resistance phenotypes: 43 isolates (29.3%) were resistant to amoxicillin, tetracyclines, chloramphenicol, streptomycin and sulphamethoxazole and 27 isolates (18.4%) to amoxicillin, amoxicillin/clavulanic acid, tetracyclines, chloramphenicol, streptomycin and sulphamethoxazole. Randomly amplified polymorphic DNA (RAPD) analysis and pulsed field gel electrophoresis (PFGE) were performed for molecular typing. Thirty-six DNA band profiles were differentiated by RAPD, and 38 by PFGE. We found a high level of clonality; 27% of strains were identical by both methods. There were additional smaller clonal lines within every area. The highest discriminatory power was obtained with PFGE, but the greatest degree of genetic diversity was observed among Salmonella Typhimurium using both RAPD and PFGE.

Imported transmissible diseases in minors coming to Spain from low-income areas.

We prospectively studied the prevalence of imported transmissible diseases in 373 immigrant children and adolescents coming from Sub-Saharan Africa, North Africa and Latin America to Salamanca, Spain. The most frequent transmissible diseases in this group were latent tuberculosis (12.7%), chronic hepatitis B virus infection (4.2%), hepatitis C virus infection (2.3%), syphilis (1.5%) and human T-lymphotropic virus type 1 or 2 infections (1.4%). A total of 24.2% of patients had serologic profiles suggesting past hepatitis B virus infection. Anti-human immunodeficiency virus antibodies were not detected in any subject. Largely asymptomatic immigrant children show a high prevalence of communicable diseases. Thus, infectious disease screenings are highly advisable in immigrant children coming from low-income countries.

Antimicrobial activity of psychotropic drugs: selective serotonin reuptake inhibitors.

Psychotropic drugs have been shown to have antimicrobial activity against several groups of microorganisms. Some of these drugs, such as the new antidepressant agents sertraline, fluoxetine and paroxetine are known to act as efflux pump inhibitors in human cells. Their activity has been studied, alone and combined with antibiotics, against bacterial species, mainly in multiply resistant strains. These agents have surprising activity, mainly against Gram positive microorganisms. They also show synergistic activity when combined with some antibiotics against several bacteria, shown by a decrease in MICs, that converts strains previously resistant to the category of sensitive, and modify physiological aspects related with pathogenicity.

[Antimicrobial drug resistance in non-typhi Salmonellae in Castilla y Leon]. / Resistencia a antimicrobianos en Salmonella no typhi en Castilla y León.

We studied the antibiotic susceptibility of 309 Salmonella isolates obtained from three hospitals serving the provinces of Salamanca, Avila and Zamora in the region of Castilla y Leon (mid-west Spain). The susceptibility to 18 antibiotics was studied using the agar dilution method, according to NCCLS guidelines, and the most common multiresistance phenotypes were determined for each province. We observed clear susceptibility differences between the two main serotypes found, S. enteritidis and S. typhimurium. Seventy percent of S. typhimurium were resistant to amoxicillin. In 44% of these isolates, amoxicillin resistance was associated with resistance to streptomycin, sulfonamides, tetracyclines and chloramphenicol. S. enteritidis was susceptible to most antibiotics tested; amoxicillin resistance was observed in 23.3%, and nalidixic acid resistance in 49.6%. Resistance to nalidixic acid was higher in S. enteritidis than in any other serotypes. According to NCCLS breakpoints, no strain was resistant to fluoroquinolones. However, according to MENSURA criteria, 9% of S. typhimurium isolates were resistant to ciprofloxacin. Resistance to cotrimazole and gentamicin was less than 10% for all the serotypes tested. The results indicate that S. typhimurium showed greater resistance and a high multidrug resistance rate. Conversely, S. enteritidis showed high resistance only to amoxicillin and nalidixic acid, though in most cases there was no correlation between this resistance and reduced susceptibility to fluoroquinolones.

In vitro activity of eight fluoroquinolones against multiresistant Stenotrophomonas maltophilia.

We studied the activity of eight fluoroquinolones (norfloxacin, ciprofloxacin, grepafloxacin, trovafloxacin, gatifloxacin, clinafloxacin, PD-117596 and PD-138312) against 58 multiresistant Stenotrophomonas maltophilia clinical strains. Norfloxacin was the least active drug (MIC(90) = 128 mg/l). Grepafloxacin, trovafloxacin and gatifloxacin activity was moderately higher (MIC(90) = 8 mg/l) than ciprofloxacin (MIC(90) = 16 mg/l). The best activity was shown by clinafloxacin and PD-138312 (MIC(90) = 4 mg/l). The most resistant strains showed similar MICs against all the fluoroquinolones tested. The highest increase of activity of newer fluoroquinolones was observed against the most sensitive strains.

In vitro activity of nonsteroidal anti-inflammatory agents, phenotiazines, and antidepressants against Brucella species.

The in vitro antimicrobial activity of streptomycin, rifampicin, tetracycline, seven nonsteroidal anti-inflammatory agents (acetyl-salicylic acid, piroxicam, indomethacin, ibuprofen, ketoprofen, sulindac, and diclofenac), and eight phenotiazine derivatives and antidepressant agents (clorpromazine, fluphenazine, amitryptiline, clomipramine, imipramine, maprotiline, sertraline, and diazepam) against 62 strains of Brucella spp. was tested. Diclofenac was the most active of the anti-inflammatory agents (MIC90 = 16 micrograms/ml). The activity of the phenotiazines and antidepressants was heterogeneous, with MIC90s ranging from 16 micrograms/ml for sertraline and 32 micrograms/ml for fluphenazine and clomipramine to > 512 micrograms/ml for diazepam. When the six most active anti-inflammatory agents and the six most active psychiatric drugs were tested at pH 5 and pH 4, the MICs remained unchanged except for those of fluphenazine; the MIC50 and MIC90 of this agent increased by one dilution.

In-vitro activity of psychiatric drugs against Corynebacterium urealyticum (Corynebacterium group D2).

We tested the in-vitro activity of amoxycillin, amoxycillin/clavulanic acid, cefotaxime, gentamicin, trimethoprim-sulphamethoxazole, tetracycline, norfloxacin, ciprofloxacin, vancomycin, teicoplanin, clindamycin and five psychiatric drugs (chlorpromazine, sertraline, fluoxetine, paroxetine and risperidone) against 32 strains of Corynebacterium urealyticum. Resistance rates exceeded 90% for all antibiotics except glycopeptides, quinolones and tetracycline. Sertraline was the most active psychiatric drug. We tested the influence of sertraline on the activity of amoxycillin, amoxycillin/clavulanic acid, cefotaxime, gentamicin, trimethoprim-sulphamethoxazole, tetracycline and ciprofloxacin. We did not observe antagonism in any case. Sertraline enhanced the activity of ciprofloxacin and tetracycline against all strains (MIC decrease: 4-64-fold for ciprofloxacin, 2-32-fold for tetracycline).

In vitro activities of beta-lactam-beta-lactamase inhibitor combinations against Stenotrophomonas maltophilia: correlation between methods for testing inhibitory activity, time-kill curves, and bactericidal activity.

The activities of ampicillin, ampicillin-sulbactam, amoxicillin, amoxicillin-clavulanic acid, ticarcillin, ticarcillin-clavulanic acid, piperacillin, piperacillin-tazobactam, aztreonam, and aztreonam-clavulanic against Stenotrophomonas maltophilia strains for which the MICs of penicillins and commercially available beta-lactam-beta-lactamase inhibitor combinations were higher than the breakpoints usually recommended for Pseudomonas aeruginosa in commercially available broth microdilution methods were tested by the agar diffusion, agar dilution, and broth microdilution methods. Time-kill curve studies were performed when discrepancies between these methods were observed. The MICs obtained by the commercially available broth microdilution method, the agar dilution method, and the broth microdilution method were almost identical. Twenty-five percent of the strains tested showed inhibition diameters of > or =15 mm for ticarcillin-clavulanic acid, and 43.7% of the strains tested showed inhibition diameters of > or =18 mm for piperacillin-tazobactam by the agar diffusion method. The time-kill curves for these strains confirmed the results obtained by dilution methods. Aztreonam-clavulanic acid (2:1) at concentrations of < or =16 microg/ml inhibited all of these strains (MIC range, 1 to 16 microg/ml). The time-kill curves confirmed this activity. The addition of piperacillin to this combination did not modify the MICs. The combination aztreonam-clavulanic acid-ticarcillin was two- to fourfold more active than aztreonam-clavulanic acid alone. We studied the inhibitory and bactericidal activities of the two most active combinations (aztreonam-clavulanic acid and aztreonam-clavulanic acid-ticarcillin) against the standard inoculum and 10 and 50 times the standard inoculum. Inoculum modifications did not modify the MICs. Both combinations showed good bactericidal activity against the standard inoculum. With 10 times the standard inoculum, minimum bactericidal concentration (MBC) results were heterogeneous (for 55% of the strains, MBCs were between the MIC and 4-fold the MIC, and for 45% of the strains MBCs were between 8- and >32-fold the MIC). With 50 times the standard inoculum, MBCs were at least 32-fold the MICs for all the strains tested.

Molecular epidemiology of drug-resistant Salmonella Typhimurium in Spain

One hundred and forty-seven Salmonella serotype Typhimurium strains isolated in three provinces in the midwest of Spain were studied. Ofthese, 93.6% were drug resistant. There were two predominant resistance phenotypes: 43 isolates (29.3%) were resistant to amoxicillin, tetracyclines,chloramphenicol, streptomycin and sulphamethoxazole and 27 isolates (18.4%) to amoxicillin, amoxicillin/clavulanic acid, tetracyclines,chloramphenicol, streptomycin and sulphamethoxazole. Randomly amplified polymorphic DNA (RAPD) analysis and pulsed field gelelectrophoresis (PFGE) were performed for molecular typing. Thirty-six DNA band profiles were differentiated by RAPD, and 38 by PFGE. Wefound a high level of clonality; 27% of strains were identical by both methods. There were additional smaller clonal lines within every area.The highest discriminatory power was obtained with PFGE, but the greatest degree of genetic diversity was observed among SalmonellaTyphimurium using both RAPD and PFGE

Se estudiaron 147 de cepas de Salmonella serotipificadas como Typhimurium procedentes de tres provincias españolas del medio-oeste. El93,6% de ellas eran resistentes a los antimicrobianos. Hubo dos fenotipos de resistencia predominantes: 43 cepas (29,3%) fueron resistentesa amoxicilina, tetraciclinas, cloranfenicaol, estreptomicina y sulfametoxazol, y 27 (18,4%) a amoxicilina, amoxicilina-ácido clavulánico, tetraciclinas,cloranfenicol, estreptomicina y sulfametoxazol. Los distintos patrones de resistencia se determinaron por técnicas de biología molecular:RAPD (Randomly Amplified Polymorphic DNA) y PFGE (Pulsed Field Gel Electrophoresis). Por RAPD se diferenciaron 36 patrones debandas, y por PFGE 38. Se encontró una proporción alta de clones: el 27% de las cepas fueron idénticas por ambos métodos. Además, encada área se encontraron algunos clones diferentes adicionales. Con PFGE se obtuvo el mayor poder discriminatorio, pero el mayor gradode diversidad genética se observó usando ambas técnicas conjuntamente