María Marta De Luca

Intestinal parasitoses and environmental factors in a rural population of Argentina, 2002-2003

We evaluate the prevalence of intestinal parasites in 504 people and the degree of association between environmental variables and parasites found in population, soil and water in a rural area of Argentina during 2002-2003. A structured survey was used to evaluate the environmental variables and fecal-human, soil and water samples were analyzed. The prevalence of parasites was 45.4%. Most prevalent protozoa were Blastocystis hominis (27.2%) and Giardia lamblia (6.9%), while the most prevalent helminth was Ascaris lumbricoides (3.8%). The analyzed environmental variables showing association (p < 0.05) with presence of parasites in population were: cardboard-tin or wooden house, dirt floor, home or communal water pump, faucet outside the house or public faucet and cesspool or latrine. Parasite forms were found in 82.3% of the soil samples and in 84.2% of the water samples. In both samples we found parasites that were also found in people. In this study we have found deficient sanitary conditions associated with presence of parasites in population and we have evidenced that contaminated soil and water were the source of these parasites.

Screening of the municipal water system of La Plata, Argentina, for human intestinal parasites.

The La Plata River, though severely contaminated by intestinal parasites through the discharge of tons of crude fecal material from a main sewage channel, nevertheless provides drinking water to two-thirds of La Plata, Argentina, after conventional purification at a processing plant. With intestinal parasitosis being endemic here, we investigated the importance of this water in transmitting such pathogens to the citys populace by means of standard methodology for sample acquisition and processing involving filter-concentration of waterborne particulates. Of 14 tap-water samples collected from the distribution network, 12 pertained to four zones (A-D) within the city center; while the remaining 2 were obtained near the processing plant, 15 kilometers outside the city. Although parasites were found within the samples derived from the four urban zones, none were detected in the specimens obtained near the plant. The four downtown areas differed from each other as to the quantity and nature of the parasites present in their water: whereas zones A and B registered similar lower levels of contaminants, C and D exhibited higher values significantly different from the former two and from each other. Given an average parasite count/l citywide of 0.38 and a probability of encountering a parasite within 11 of water of 0.32, the municipal network is seen to contribute to the transmission of intestinal parasites. A routine system of water-quality control is therefore needed throughout the city along with the establishment of infrastructures for locating and eliminating peripheral sources of contamination.

Nitrogen‐Gas Bubbling during the Cultivation of Clostridium tetani Produces a Higher Yield of Tetanus Toxin for the Preparation of Its Toxoid

We investigated the effect of exposing cultures of Clostridium tetani to nitrogen (N2) gas on the recovery of tetanus toxin to be processed for the preparation of its toxoid. N2 was bubbled through nine 10‐liter cultures during the growth of the bacteria, while nine parallel control incubations were maintained without bubbling. We found that treatment of the C. tetani anaerobes with an inert gas in this manner during cultivation produced a highly significant increase in the yield of tetanus toxin from them in comparison with the standard procedure.

Antimicrobial Resistance Profiles of Enterococcus faecalis and Enterococcus faecium Isolated from Artisanal Food of Animal Origin in Argentina

Enterococci are part of the indigenous microbiota of human gastrointestinal tract and food of animal origin. Enterococci inhabiting non-human reservoirs play a critical role in the acquisition and dissemination of antimicrobial resistance determinants. The aim of this work was to investigate the antimicrobial resistance in Enterococcus faecalis and Enterococcus faecium strains recovered from artisanal food of animal origin. Samples of goat cheese (n = 42), cow cheese (n = 40), artisanal salami (n = 30), and minced meat for the manufacture of hamburgers (n = 60) were analyzed. Phenotypic and genotypic tests for species-level identification of the recovered isolates were carried out. Minimum inhibitory concentration (MIC) study for in vitro quantitative antimicrobial resistance assessment was performed, and 71 E. faecalis and 22 E. faecium were isolated. The recovered enterococci showed different multi-drug resistance patterns that included tretracycline, erythromycin, ciprofloxacin, linezolid, penicillin, ampicillin, vancomycin, teicoplanin, gentamicin (high-level resistance), and streptomycin (high-level resistance). VanA-type E. faecium were detected. β-lactamase activity was not observed. Artisanal foods of animal origin act as a non-human reservoir of E. faecalis and E. faecuim strains, expressing multi-resistance to antimicrobials. In conclusion, the implementation of a continuous antimicrobial resistance surveillance in enterococci isolated from artisanal food of animal origin is important.

Resistance to Antibiotics in Injured Coliforms Isolated from Drinking Water

We studied the antibiotic sensitivity of injured coliforms isolated from drinking water of La Plata, Argentina. The antibiotic sensitivity test by the agar diffusion method were proved in: Klebsiella oxytoca (14 strains), Enterobacter aerogenes (4 strains) and Enterobacter cloacae genomic group 3 (14 strains). We found that while these impaired total coliforms were sensitive to piperacillin‐tazobactam (TAZ), netilmicin (NTL), ofloxacin (OFLX), and norfloxacin (NFLX) (100%), they had resistant to aminopenicillin‐sulbactam (AMS) and nitrofurantoin (NIT) (100%). The resistance to antibiotics demonstrated in these strains would point to the need to promote a rational and judicious use of antimicrobial agents while at the same time implementing a program of active vigilance aimed at ensuring the highest quality of drinking water throughout the system.

Molecular Genetic Profiling of Clinical and Foodborne Strains of Enterococci with High Level Resistance to Gentamicin and Vancomycin

Enterococci often acquire antimicrobial resistance through horizontal gene transfer. Relatedness between enterococci with high level resistance to gentamicin and vancomycin isolated from humans, food and hospital environment in Tandil County (Argentina) was investigated. PCR amplification for species determination was carried out. Resistance to seven antimicrobials was studied; virulence genes (esp, cylA), vancomycin and gentamicin resistance genes were investigated. In the isolates with high level antimicrobial resistance (gentamicin, vancomycin), pulse-field gel electrophoresis was performed. Vancomycin-resistant E. faecium (n:13) were recovered from human, food and hospital environment samples. All the isolates expressed high-level vancomycin and teicoplanin (vanA genotype), as well high-level gentamicin and streptomycin resistance. Vancomycin-resistant E. faecium were distributed among seven clonal types; esp gene was detected in clinical strains. There was no clonal relationship with food vanA E. faecium, but these strains could pose a risk in intra/inter genus transfer of vanA determinant to human-adapted strains. High-level gentamicin resistant E. faecalis (n:7) were recovered from human and food samples. Glycopeptide resistance was not observed; cylA gene was detected in most of the clinical high-level gentamicin resistant E. faecalis isolates. PFGE patterns showed four clonal types in high-level gentamicin resistant E. faecalis strains; there was demonstrated clonal relatedness between isolates from different origin. In Argentina, this is the first study showing a clonal relationship between high-level gentamicin resistant E. faecalis isolated from food and humans. These results encourage the study of dissemination of clonal complexes with mobile resistance genes.