Application of real-time PCR for the differentiation of Entamoeba histolytica and E. dispar in cyst-positive faecal samples from 130 immigrants living in Spain.

In an effort to improve the diagnosis of intestinal amoebiasis, a real-time PCR has been used for the detection and differentiation of Entamoeba histolytica and E. dispar infections in African or South American immigrants who live in Spain. Faecal samples from all of the 130 subjects had apparently been found to contain E. histolytica/E. dispar cysts by microscopical examination. Using the real-time PCR, E. histolytica DNA was detected in faecal samples from only 10 (7.7%) of the immigrants, with E. dispar DNA detected in the samples from another 117 (90.0%) of the subjects. The use of such PCR in the routine investigation of patients found positive for E. histolytica/E. dispar cysts (by microscopy) is recommended, especially in non-endemic areas.

[Factors of pathogenicity, biotype, serotype and antimicrobial sensitivity of 150 clinical isolates of Yersinia enterocolitica (1992-1994)]. / Factores de patogenicidad, biotipo, serotipo y sensibilidad antimicrobiana de 150 aislamientos clínicos de Yersinia grupo enterocolitica (1992-1994).

BACKGROUND: Yersinia enterocolitica is an important pathogen in temperate climates. The heterogeneity of the microorganisms covered by this denomination has a made grouping and identification schemes necessary. METHODS: A series of 150 different, consecutive isolates from patients with diarrheic syndrome living in an urban area with a population of approximately 500,000 inhabitants, were studied in order to evaluate their biochemical, antigenic and sensitivity characteristics. RESULTS: There was a high degree of uniformity among the strains isolated, 144 (96%) of which were identified as Yersinia enterocolitica sensu stricto, biotype 4, serotype 0:3. These strains presented, almost invariably, the same susceptibility pattern, being sensitive to amoxicillin/clavulanic acid, piperacillin, cefamandole, cefoxitin, gentamicin, amikacin, tetracycline and cotrimoxazole, and highly resistant to ampicillin, ticarcillin and cephazotin. In addition, 5 strains of Yersinia frederiksenii were isolated. The biochemical, epidemiological and sensitivity characteristics of these strains differed from those invariably found in the rest of the isolates. CONCLUSIONS: The data obtained in this study, shown a high degree of uniformity in the strains of Yersinia enterocolitica isolated in our area in recent years, with regard to both their biochemical characteristics and their sensitivity patterns. The isolations of the other biogroups may be regarded as extremely infrequent in the stool culture of patients with diarrhea treated in our hospitals.

Antimicrobial susceptibilities of Campylobacter jejuni and Campylobacter coli to 12 beta-lactam agents and combinations with beta-lactamase inhibitors.

The in vitro activities of 12 beta-lactam agents against 100 thermophilic Campylobacter strains were tested. Beta-Lactamase production was detected in 88% of all strains tested. Clavulanic acid was the best inhibitor by susceptibility testing. The beta-lactams which displayed high levels of in vitro activity against Campylobacter isolates were imipenem, amoxicillin-clavulanic acid, and cefepime and, to a lesser degree, amoxicillin, ampicillin, and cefotaxime.

[The E test and quinolone-resistant Campylobacter jejuni]. / Test E y Campylobacter jejuni resistente a quinolonas.

BACKGROUND: The E-Test is a quantitative technique for the determination of antimicrobial sensitivity. The system is based on the diffusion of a predefined exponential gradient in a determined antibiotic, using an inert plastic support which is applied to a solid culture medium and it is an alternative method for antibiotic sensitivity testing. Of the series published, some specifically include microorganisms considered fastidious or difficult to grow, such as Campylobacter jejuni. In recent years a progressive increase in the resistance of these microorganisms to antibiotics, such as the fluoroquinolone group, has been observed. The aim of the present study was to compare in 10 antimicrobial agents the results of E-Test with those of the dilution-agar technique in 57 strains of ciprofloxacine-resistant Campylobacter jejuni. METHODS: In this serie we studied 57 ciprofloxacine-resistant strains of Campylobacter jejuni using the E-Test and comparing the results with those obtained in a parallel study employing the agar dilution technique. RESULTS: The two methods coincided in the classification of the isolates as sensitive or resistant, except in the case of clindamycine (1 strain) and tetracycline (8 strains). The MIC's values obtained were similar (+/- 1 log2 dilution) in near of 90% of isolates for ciprofloxacine and erythromycine. However, for ampicilline, amoxycilline/clavulanic acid and gentamicin these results were obtained in less than 30%. CONCLUSIONS: In general, the E-Test may be considered a valid alternative in the follow-up and control of resistant strains of Campylobacter jejuni, isolated with increasing frequency in clinical microbiology laboratories, although the correlation with agar-dilution techniques was only discrete and its relatively high cost could limit their general use.

Susceptibilities of fluoroquinolone-resistant strains of Campylobacter jejuni to 11 oral antimicrobial agents.

The resistance of Campylobacter jejuni strains to the fluoroquinolones is increasingly frequent, and in our area it reaches nearly 50%. We studied the susceptibilities of 60 of these strains to 11 oral antibiotics. All strains except one were susceptible to the macrolides tested, with azithromycin being the most active agent tested. Of the rest of the antibiotics studied, amoxicillin-clavulanic acid, clindamycin, and fosfomycin displayed good in vitro activities. Knowledge of the susceptibilities of these microorganisms to a varied group of oral agents is necessary in view of the appearance of multiresistant strains, such as those included in our series.

Bacteriologic characteristics and antimicrobial susceptibility of 70 clinically significant isolates of Streptococcus milleri group.

The phenotypical characteristics of 70 clinical isolates of Streptococcus milleri group were analyzed. Association of the three species with particular sites of isolation could not be demonstrated in all cases, but S. anginosus strains predominated in abdominal area, while S. intermedius was isolated mainly in hepatic abscesses. Penicillin G and other beta-lactams showed good in vitro activity against these streptococci, whereas > 10% exhibited resistance to erythromycin and clindamycin. Resistance to tetracycline reached almost 40%. All of the isolates were uniformly susceptible to vancomycin, chloramphenicol, and trimethoprim.

Bacteremia by multidrug-resistant Capnocytophaga sputigena.

A case of bacteremia caused by a multiresistant strain of Capnocytophaga sputigena in a patient with hematological malignancy is described. The strain presented with a pattern of marked resistance to beta-lactams, with MICs of > 256 mg/liter for ampicillin, ticarcillin, piperacillin, cefazolin, and cefuroxime, 64 mg/liter for cefotaxime, and 32 mg/liter for ceftazidime. In addition, the MIC of ciprofloxacin was 16 mg/liter. Both of these groups of antimicrobial agents are frequently used in the empiric treatment of infections in immunocompromised patients. The appearance of resistant strains suggests the need for antimicrobial susceptibility studies in all patients with severe infections caused by Capnocytophaga spp. or other capnophilic organisms present in the oral microflora of these patients.

Susceptibilities of ampicillin-resistant strains of Salmonella other than S. typhi to 10 antimicrobial agents.

Ampicillin-resistant strains of Salmonella other than S. typhi constitute a health problem. We tested the antimicrobial susceptibilities to 10 antibiotics of 57 of these strains isolated in a 30-month period. The rates of resistance were as follows: chloramphenicol, 40.3%; tetracycline, 33.3%; gentamicin, 5.3%; co-trimoxazole, 5.3%; nalidixic acid, 1.8%; and amoxicillin-clavulanic acid, cefotaxime, ceftriaxone, aztreonam, and ciprofloxacin, 0%. In our experience, there are alternative antibiotics with excellent in vitro activities.