Antibiotic resistance patterns of Escherichia coli isolates from different aquatic environmental sources in León, Nicaragua.

Antibiotic-resistant bacteria have emerged due to the selective pressure of antimicrobial use in humans and animals. Water plays an important role in dissemination of these organisms among humans, animals and the environment. We studied the antibiotic resistance patterns among 493 Escherichia coli isolates from different aquatic environmental sources collected from October 2008 to May 2009 in León, Nicaragua. High levels of antibiotic resistance were found in E. coli isolates in hospital sewage water and in eight of 87 well-water samples. Among the resistant isolates from the hospital sewage, ampicillin, chloramphenicol, ciprofloxacin, nalidixic acid, trimethoprim-sulphamethoxazole was the most common multi-resistance profile. Among the resistant isolates from the wells, 19% were resistant to ampicillin, ceftazidime, ceftriaxone, cefotaxime, chloramphenicol, ciprofloxacin, gentamicin, nalidixic acid and trimethoprim-sulphamethoxazole. E. coli producing ESBL and harbouring bla(CTX-M) genes were detected in one of the hospital sewage samples and in 26% of the resistant isolates from the well-water samples. The bla(CTX-M-9) group was more prevalent in E. coli isolates from the hospital sewage samples and the bla(CTX-M-1) group was more prevalent in the well-water samples.

Antibiotic resistance patterns in gram-negative and gram-positive bacteria causing septicemia in newborns in León, Nicaragua: correlation with environmental samples.

The aim of this study was to identify the bacteria causing neonatal septicemia in a neonatal intensive care unit (NICU) in León, Nicaragua and its relation with bacteria isolated from the environment at the NICU. Our data showed that 74% (34/46) of the bacteria related to newborns with septicemia were Gram-negative and highly resistant to beta-lactams (>85%) and aminoglycosides (80%), leading to treatment failure in 10 neonates with fatal outcome. Although, the prevalence of Gram-positive bacteria (26%) was lower than Gram-negative bacteria, Staphylococcus epidermidis was related to the death of three newborns. No clonal similarity was found among Enterobacter cloacae , Escherichia coli and Serratia liquefaciens isolated from the neonates with septicemia and the NICU environment. However, in order to improve the outcome for neonates with septicemia, infection control practices and appropriate empirical therapy should be considered to reduce the high prevalence of extended-spectrum beta-lactamase (ESBL)-producing Gram-negative bacteria isolated from neonates with septicemia (80%) and from the NICU environment (34%).

A randomized, double-blind, placebo-controlled trial of single-dose intravenous secretin as treatment for children with autism.

OBJECTIVE: To determine whether a single injection of intravenous secretin results in measurable improvements in socialization and/or communication skills in children with autism. STUDY DESIGN: Sixty subjects with autism were randomly selected and assigned to either treatment or placebo group. Subjects in the treatment group received 2.0 clinical units of secretin per kilogram of body weight as a single intravenous dose. Subjects in the placebo group received normal saline solution. Neurodevelopmental and behavioral assessments were performed for all subjects before injection and at 3 and 6 weeks after injection. RESULTS: Assessment of language skills and parents' behavioral assessments revealed no significant differences between the treatment and placebo groups. Raters' assessments of severity of autistic symptoms did not differ for the 2 groups at 6 weeks after injection. A marginally statistically significant improvement in autistic behaviors was seen in the treatment group at 3 weeks after injection (P =.051). CONCLUSIONS: A single dose of intravenous secretin does not appear to have significant effects on either parents' perception of autistic behaviors or language skills at 6 weeks after injection. Transient, marginally significant improvements in autistic behaviors may occur in some children.

The outer membrane of Brucella ovis shows increased permeability to hydrophobic probes and is more susceptible to cationic peptides than are the outer membranes of mutant rough Brucella abortus strains.

The permeability of the outer membrane (OM) to hydrophobic probes and its susceptibility to bactericidal cationic peptides were investigated for natural rough Brucella ovis and for mutant rough Brucella abortus strains. The OM of B. ovis displayed an abrupt and faster kinetic profile than rough B. abortus during the uptake of the hydrophobic probe N-phenyl-naphthylamine. B. ovis was more sensitive than rough B. abortus to the action of cationic peptides. Bactenecins 5 and 7 induced morphological alterations on the OMs of both rough Brucella strains. B. ovis lipopolysaccharide (LPS) captured considerably more polymyxin B than LPSs from both rough and smooth B. abortus strains. Polymyxin B, poly-L-lysine, and poly-L-ornithine produced a thick coating on the surfaces of both strains, which was more evident in B. ovis than in rough B. abortus. The distinct functional properties of the OMs of these two rough strains correlate with some structural differences of their OMs and with their different biological behaviors in animals and culture cells.

Antimicrobial susceptibility of anaerobicand aerobic bacteria isolated from patientswith mixed infections in Nicaragua.

The agar dilution method was used to test the activity of ampicillin, benzylpenicillin, cefoxitin, imipenem, clindamycin, metronidazole, chloramphenicol, gentamicin, methicillin and vancomycin against 241 anaerobic and 227 aerobic bacteria isolated from 136 patients with intraabdominal infections and 49 with nonintraabdominal infections. Beta-lactamase production was tested in all strains. Overall, imipenem, metronidazole and chloramphenicol were the most active antimicrobial agents against anaerobic bacteria followed by clindamycin. Only the Bacteroides fragilis group was shown to be less susceptible to clindamycin (MIC90 8 mg/l). Ampicillin and cefoxitin were the least active beta-lactam antibiotics against the most common isolated B. fragilis group strains (MIC(90) >1024 and 64 mg/l, respectively) and against Escherichia coli strains (MIC(90) >1024 and >1024 mg/l, respectively). Chloramphenicol showed low activity against the Gram-negative aerobic bacteria, while gentamicin had good activity against the aerobic bacteria tested, except for E. coli and Pseudomonas. Among the Gram-positive aerobic and anaerobic bacteria tested, Staphylococcus aureus was shown to be less susceptible to beta-lactam antibiotics (29% were methicillin resistant). No vancomycin-resistant S. aureus strains were found. A good correlation between beta-lactamase production and beta-lactam resistance was observed.

Antimicrobial susceptibility of anaerobic and aerobic bacteria isolated from patients with mixed infections in Nicaragua.

The agar dilution method was used to test the activity of ampicillin, benzylpenicillin, cefoxitin, imipenem, clindamycin, metronidazole, chloramphenicol, gentamicin, methicillin and vancomycin against 241 anaerobic and 227 aerobic bacteria isolated from 136 patients with intraabdominal infections and 49 with nonintraabdominal infections. Beta-lactamase production was tested in all strains. Overall, imipenem, metronidazole and chloramphenicol were the most active antimicrobial agents against anaerobic bacteria followed by clindamycin. Only the Bacteroides fragilis group was shown to be less susceptible to clindamycin (MIC90 8 mg/l). Ampicillin and cefoxitin were the least active beta-lactam antibiotics against the most common isolated B. fragilis group strains (MIC(90) >1024 and 64 mg/l, respectively) and against Escherichia coli strains (MIC(90) >1024 and >1024 mg/l, respectively). Chloramphenicol showed low activity against the Gram-negative aerobic bacteria, while gentamicin had good activity against the aerobic bacteria tested, except for E. coli and Pseudomonas. Among the Gram-positive aerobic and anaerobic bacteria tested, Staphylococcus aureus was shown to be less susceptible to beta-lactam antibiotics (29% were methicillin resistant). No vancomycin-resistant S. aureus strains were found. A good correlation between beta-lactamase production and beta-lactam resistance was observed.

Heterogeneity of Brucella abortus lipopolysaccharides.

This work demonstrates that Brucella lipopolysaccharide (LPS) preparations are a family of related molecules which display heterogeneity not only at the level of the O polysaccharide, but also at the core oligosaccharide and the lipid A. Sodium dodecyl sulphate/polyacrylamide gel electrophoresis and Western blotting showed that LPS from Brucella strains displayed molecular weight and antigenic heterogeneity. Smooth-type LPS (S-LPS) from B. abortus demonstrated three broad high-molecular-weight bands corresponding to S-LPS, and a low-molecular-weight band corresponding to O antigen lacking rough-type LPS (R-LPS). B. abortus R-LPS displayed four bands in increasing proportions as the molecular weight diminished. Immunodetection on high-performance thin-layer chromatography (HPTLC) with monoclonal antibodies (mAb) showed that R-LPS displayed three diffuse bands. HPTLC of O polysaccharide revealed two fast migrating bands recognized by antibodies. Gel chromatography and HPTLC analysis of core oligosaccharides from R-LPS demonstrated molecular weight heterogeneity as well as heterogeneous banding pattern, with no obvious correspondence between the two profiles. Immunodetection of lipid A on HPTLC plates revealed two major and three minor bands. Reactivity with mAbs suggested that regardless of the lipid A heterogeneity the basic structure of lipid A backbone is maintained.

The status of undergraduate implant education in dental schools outside the United States.

Over the past 20 years the incorporation of implant dentistry into academia has been documented in some detail for North American dental schools but has not been pursued on an international level. In June of 1993, we surveyed 51 dental schools outside of the United States affiliated with the University of Pennsylvania School of Dental Medicine's Office of International Relations concerning their teaching involvement with implant dentistry. Results from the 44 (86 percent) responding schools suggest that implant dentistry is being incorporated into predoctoral curriculums. Industrialized countries were more inclined to provide implant education. Insufficient time and the thought that the predoctoral level was not the place for implant dentistry were cited as some of the reasons for not incorporating implant dentistry into the curriculum. Oral surgery, prosthodontics, and periodontics departments developed and administered the implant curriculum. Formats varied among schools with respect to allotted time, curricular placement, laboratory experience, and clinical participation. Didactic material most frequently presented included a historical overview, diagnosis and treatment planning, classification of dental implants, and surgical and prosthetic concepts. Clinical involvement varied from actual implant placement to observation of prosthodontic procedures. Results were categorized based on the TOEFL (Test of English as a Foreign Language) classification of countries in six regions.

Structural studies of the O-antigenic polysaccharide of an enteroaggregative Escherichia coli strain.

The polysaccharide part of the lipopolysaccharide obtained from an enteroaggregative Escherichia coli strain isolated from a young child with diarrhoea in Santiago, Chile (strain 73-1) was investigated. Sugar and methylation analyses of native and partially degraded polysaccharide together with 1H-NMR and 13C-NMR spectroscopy revealed that the polysaccharide is built of pentasaccharide repeating units. The structure of the repeating unit of E. coli strain 73-1 O-polysaccharide is (formula: see text)