Teresa Llovet

Antibiotic resistance trends in enteropathogenic bacteria isolated in 1985-1987 and 1995-1998 in Barcelona.

ABSTRACT Trends in resistance to antimicrobial agents used for therapy have been evaluated with 3,797 enteropathogenic bacteria,Campylobacter, Salmonella,Shigella, and Yersinia, between 1985–1987 and 1995–1998. The greater increase in the rate of resistance was observed in Campylobacter jejuni for quinolones (from 1 to 82%) and tetracycline (from 23 to 72%) and in gastroenteric salmonellae for ampicillin (from 8 to 44%), chloramphenicol (from 1.7 to 26%), and trimethoprim-sulfamethoxazole and nalidixic acid (from less than 0.5 to 11%). Multidrug resistance was detected in several Salmonella serotypes. In the 1995–1998 period, 76% of Shigella strains were resistant to trimethoprim-sulfamethoxazole, 43% were resistant to ampicillin, and 39% were resistant to chloramphenicol. Seventy-two percent ofYersinia enterocolitica O3 strains were resistant to streptomycin, 45% were resistant to sulfonamides, 28% were resistant to trimethoprim-sulfamethoxazole, and 20% were resistant to chloramphenicol.

Effect of Lactobacillus johnsonii La1 and antioxidants on intestinal flora and bacterial translocation in rats with experimental cirrhosis

BACKGROUND/AIMS Probiotics and antioxidants could be alternatives to antibiotics in the prevention of bacterial infections in cirrhosis. The aim of the present study was to determine the effect of Lactobacillus johnsonii La1 and antioxidants on intestinal flora, endotoxemia, and bacterial translocation in cirrhotic rats. METHODS Twenty-nine Sprague-Dawley rats with cirrhosis induced by CCl(4) and ascites received Lactobacillus johnsonii La1 10(9)cfu/day in vehicle (antioxidants: vitamin C+glutamate) (n=10), vehicle alone (n=11), or water (n=8) by gavage. Another eight non-cirrhotic rats formed the control group. After 10 days of treatment, a laparotomy was performed to determine microbiological study of ileal and cecal feces, bacterial translocation, endotoxemia, and intestinal malondialdehyde (MDA) levels as index of intestinal oxidative damage. RESULTS Intestinal enterobacteria and enterococci, bacterial translocation (0/11 and 0/10 vs. 5/8, P<0.01), and ileal MDA levels (P<0.01) were lower in cirrhotic rats treated with antioxidants alone or in combination with Lactobacillus johnsonii La1 compared to cirrhotic rats receiving water. Only rats treated with antioxidants and Lactobacillus johnsonii La1 showed a decrease in endotoxemia with respect to cirrhotic rats receiving water (P<0.05). CONCLUSIONS Antioxidants alone or in combination with Lactobacillus johnsonii La1 can be useful in preventing bacterial translocation in cirrhosis.

Intestinal mucosal oxidative damage and bacterial translocation in cirrhotic rats

Background Bacterial translocation plays an important role in the pathogenesis of spontaneous bacterial peritonitis mainly due to intestinal bacterial overgrowth. Alterations in the functional integrity of the intestinal barrier caused by an increased production of free radical metabolites as a consequence of portal hypertension could also facilitate bacterial translocation in cirrhotic rats. Objective The aim of the study was to determine intestinal mucosal lipid peroxidation and neutrophil infiltration and their relationship with portal hypertension and bacterial translocation in cirrhotic rats. Design Eighteen male Sprague–Dawley rats with cirrhosis induced by carbon tetrachloride, administered by gavage, and eight control rats were included in the study. Methods Samples of jejunum, ileum and caecum were obtained by laparotomy for the determination of malondialdehyde and myeloperoxidase as indexes of lipid peroxidation and neutrophil infiltration, respectively. Samples of ascitic and pleural fluids, mesenteric lymph nodes and ileal stools were obtained for the culture of microoganisms. Results The concentration of malondialdehyde was significantly higher in ileal and caecal, but not in jejunal mucosa, in cirrhotic rats, mainly in those with ascites (P < 0.01), as compared to control rats (P < 0.01), and in cirrhotic rats with bacterial translocation compared to those without bacterial translocation (P < 0.01). No differences between groups were observed in the concentrations of myeloperoxidase in jejunum, ileum or caecum. A direct correlation between ileal malondialdehyde and portal pressure was observed (P < 0.01). Conclusions Cirrhotic rats, particularly those with ascites and bacterial translocation, show increased malondialdehyde levels in ileal and caecal mucosa. These results suggest that mucosal oxidative damage in ileum and caecum could favour bacterial translocation in cirrhotic rats.

Cephalosporin-resistant Escherichia coli among Summer Camp Attendees with Salmonellosis

Investigation of an acute gastroenteritis outbreak involving >100 persons at a summer camp in Girona, Spain, in June 2002 led to the detection of Salmonella and extended-spectrum cephalosporin-resistant Escherichia coli (ESCREC). Stool cultures were performed for 22 symptomatic campers, three asymptomatic food handlers, and 10 healthy household members. Of the 22 campers, 19 had Salmonella enterica, 9 had an ESCREC strain carrying an extended-spectrum β-lactamase, and 2 had a second ESCREC strain carrying a plasmidic cephamycinase. Related ESCREC were detected in two (salmonella-negative) asymptomatic food handlers and in none of the healthy household members. Fecal ESCREC and its β-lactamases and plasmids were extensively characterized. Three of the five ESCREC clones were recovered from multiple hosts. The apparent dissemination of ESCREC suggests a food or water vehicle. The observed distribution of resistance plasmids and β-lactamase genes in several clones indicates a high degree of horizontal transfer. Heightened vigilance and increased efforts must be made to discover the reservoirs and vehicles for community dissemination of ESCREC.

Serological Diagnosis of Chronic Chagas Disease: Is It Time for a Change?

ABSTRACT Chagas disease has spread to areas that are nonendemic for the disease with human migration. Since no single reference standard test is available, serological diagnosis of chronic Chagas disease requires at least two tests. New-generation techniques have significantly improved the accuracy of Chagas disease diagnosis by the use of a large mixture of recombinant antigens with different detection systems, such as chemiluminescence. The aim of the present study was to assess the overall accuracy of a new-generation kit, the Architect Chagas (cutoff, ≥1 sample relative light units/cutoff value [S/CO]), as a single technique for the diagnosis of chronic Chagas disease. The Architect Chagas showed a sensitivity of 100% (95% confidence interval [CI], 99.5 to 100%) and a specificity of 97.6% (95% CI, 95.2 to 99.9%). Five out of six false-positive serum samples were a consequence of cross-reactivity with Leishmania spp., and all of them achieved results of <5 S/CO. We propose the Architect Chagas as a single technique for screening in blood banks and for routine diagnosis in clinical laboratories. Only gray-zone and positive sera with a result of ≤6 S/CO would need to be confirmed by a second serological assay, thus avoiding false-positive sera and the problem of cross-reactivity with Leishmania species. The application of this proposal would result in important savings in the cost of Chagas disease diagnosis and therefore in the management and control of the disease.

Development of an Experimental Model of Induced Bacterial Peritonitis in Cirrhotic Rats With or Without Ascites

BACKGROUND:Spontaneous bacterial peritonitis (SBP) is a severe complication of cirrhotic patients associated with a high mortality.AIM:To develop an available experimental model of induced bacterial peritonitis in cirrhosis.MATERIALSprague-Dawley rats with carbon-tetrachloride-induced cirrhosis with (N = 22) or without (N = 101)AND  METHODS:ascites were randomized to receive an intraperitoneal administration of different concentrations of Escherichia coli (E. coli) diluted in 1 mL of sterile water in ascitic rats and in different volumes in nonascitic rats. A subgroup of nonascitic animals received ceftriaxone 4 h after E. coli inoculation. Mortality of rats was evaluated 24 h after bacterial inoculation.RESULTS:None of the rats receiving sterile water alone and only one infected with 107 cfu of E. coli died. Ascitic rats showed a lower mortality rate than nonascitic rats infected with 108 or 109 cfu of E. coli (P < 0.05). Mortality was higher with 109 cfu than with 108 cfu of E. coli in ascitic (P NS) and nonascitic (P < 0.01) rats. A trend was noted to ward higher mortality in nonascitic rats inoculated with 108 cfu with increasing water volumes. A marked peritoneal polymorphonuclear cell response was observed 4 h after E. coli injection in both ascitic and nonascitic rats. Antibiotic therapy significantly reduced the mortality rate of rats infected with 108 cfu (P < 0.01).CONCLUSIONS:This experimental model of induced bacterial peritonitis in cirrhosis with or without ascites may represent a useful tool for the study of pathogenic events postinfection and for the design of new therapeutic strategies to treat patients with SBP.

Resistance of Salmonella and Campylobacter species to antimicrobial agents.

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Towards a New Strategy for Diagnosis of Congenital Trypanosoma cruzi Infection

ABSTRACT The immigration of Latin American women of childbearing age has spread the congenital transmission of Chagas disease to areas of nonendemicity, and the disease is now a worldwide problem. Some European health authorities have implemented screening programs to prevent vertical transmission, but the lack of a uniform protocol calls for the urgent establishment of a new strategy common to all laboratories. Our aims were to (i) analyze the trend of passive IgG antibodies in the newborn by means of five serological tests for the diagnosis and follow-up of congenital Trypanosoma cruzi infection, (ii) assess the utility of these techniques for diagnosing a congenital transmission, and (iii) propose a strategy for a prompt, efficient, and cost-effective diagnosis of T. cruzi infection. In noninfected newborns, a continuous decreasing trend of passive IgG antibodies was observed, but none of the serological assays seroreverted in any the infants before 12 months. From 12 months onwards, serological tests achieved negative results in all the samples analyzed, with the exception of the highly sensitive chemiluminescent microparticle immunoassay (CMIA). In contrast, in congenitally infected infants, the antibody decline was detected only after treatment initiation. In order to improve the diagnosis of congenital T. cruzi infection, we propose a new strategy involving fewer tests that allows significant cost savings. The protocol could start 1 month after birth with a parasitological test and/or a PCR. If negative, a serological test would be carried out at 9 months, which if positive, would be followed by another at around 12 months for confirmation.

Risk of underdiagnosing amebic dysentery due to false-negative Entamoeba histolytica antigen detection.

Entamoeba histolytica antigen assays on stool are widely used to diagnose amebiasis. We report a case of confirmed amebic colitis with a false-negative antigen detection that became positive after treatment. Our results indicate that these assays may underdiagnose acute amebic infection when used alone and should be used cautiously.

Introducing automation to the molecular diagnosis of Trypanosoma cruzi infection: A comparative study of sample treatments, DNA extraction methods and real-time PCR assays

Background Polymerase chain reaction (PCR) has become a useful tool for the diagnosis of Trypanosoma cruzi infection. The development of automated DNA extraction methodologies and PCR systems is an important step toward the standardization of protocols in routine diagnosis. To date, there are only two commercially available Real-Time PCR assays for the routine laboratory detection of T. cruzi DNA in clinical samples: TCRUZIDNA.CE (Diagnostic Bioprobes Srl) and RealCycler CHAG (Progenie Molecular). Our aim was to evaluate the RealCycler CHAG assay taking into account the whole process. Methodology/Principal findings We assessed the usefulness of an automated DNA extraction system based on magnetic particles (EZ1 Virus Mini Kit v2.0, Qiagen) combined with a commercially available Real-Time PCR assay targeting satellite DNA (SatDNA) of T. cruzi (RealCycler CHAG), a methodology used for routine diagnosis in our hospital. It was compared with a well-known strategy combining a commercial DNA isolation kit based on silica columns (High Pure PCR Template Preparation Kit, Roche Diagnostics) with an in-house Real-Time PCR targeting SatDNA. The results of the two methodologies were in almost perfect agreement, indicating they can be used interchangeably. However, when variations in protocol factors were applied (sample treatment, extraction method and Real-Time PCR), the results were less convincing. A comprehensive fine-tuning of the whole procedure is the key to successful results. Guanidine EDTA-blood (GEB) samples are not suitable for DNA extraction based on magnetic particles due to inhibition, at least when samples are not processed immediately. Conclusions/Significance This is the first study to evaluate the RealCycler CHAG assay taking into account the overall process, including three variables (sample treatment, extraction method and Real-Time PCR). Our findings may contribute to the harmonization of protocols between laboratories and to a wider application of Real-Time PCR in molecular diagnostic laboratories associated with health centers.