Effect of probiotic lactobacilli supplementation on growth parameters, blood profile, productive performance, and fecal microbiology in feedlot cattle

Lactic acid bacteria (LAB) selected on the basis of probiotic characteristics were administered to beef feedlot catlle and the effect on body condition/growth and nutritional-metabolic status as well as on E. coli O157:H7 fecal shedding, were investigated. A feeding trials involving 126 steers were used to evaluate the effects of Lactobacillus acidophilus CRL2074, Limosilactobacillus fermentum CRL2085 and Limosilactobacillus mucosae CRL2069 and their combinations (5 different probiotic groups and control) when 10⁷-10⁸ CFU/animal of each probiotic group were in-feed supplemented. Cattle were fed a high energy corn-based diet (16 to 88%) and samples from each animal were taken at 0, 40, 104 and 163 days. In general, animals body condition and sensorium state showed optimal muscle-skeletal development and behavioral adaption to confinement; no nasal/eye discharges and diarrheic feces were observed. The nutritional performance of the steers revealed a steady increase of biometric parameters and weight. Animals supplied with L. mucosae CRL2069 for 104 days reached the maximum mean live weight (343.2 kg), whereas the greatest weight daily gain (1.27 ± 0.16 Kg/day) was obtained when CRL2069 and its combination with L. fermentum CRL2085 (1.26 ± 0.11 kg/day) were administered during the complete fattening cycle. With several exceptions, bovine cattle blood and serum parameters showed values within referential ranges. As a preharvest strategy to reduce Escherichia coli O157:H7 in cattle feces, CRL2085 administered during 40 days decreased pathogen shedding with a reduction of 43% during the feeding period. L. fermentum CRL2085 and L. mucosae CRL2069 show promise for feedlot cattle feeding supplementation to improve metabolic-nutritional status, overall productive performance and to reduce E. coli O157:H7 shedding, thus decreasing contamination chances of meat food products.

[Presence of Legionella spp. in household drinking water reservoirs in Resistencia, Chaco, Argentina. Preliminary report]

Legionella spp. is an environmental bacterium that can survive in a wide range of physicochemical conditions and may colonize distribution systems of drinking water and storage tanks. Legionella pneumophila is the major waterborne pathogen that can cause 90% of Legionnaires' disease cases. The aim of this study was to detect the presence of Legionella spp. in household drinking water tanks in the city of Resistencia, Chaco. The detection of Legionella in water samples was performed by culture methods as set out in ISO 11731:1998. Thirty two water samples were analyzed and Legionella spp. was recovered in 12 (37.5%) of them. The monitoring of this microorganism in drinking water is the first step towards addressing the control of its spread to susceptible hosts.

[Detection of virulence genes of the enteroaggregative pathotype in Escherichia coli strains isolated from groundwater sources in the province of Chaco, Argentina]

Groundwater is an important source of drinking water for many communities in Northern Argentina; particularly, in the province of Chaco, where about 14% of households use this natural resource. Enteroaggregative Escherichia coli is an emerging pathogen whose global importance in public health has increased in recent years. Despite the significant risk of disease linked to contaminated water exposure, the prevalence of E. coli pathotypes in aquatic environments is still not so well defined. The aim of the present study was to detect the presence of typical enteroaggregative E. coli through the recognition of its virulence factors aap, AA probe and aggR by molecular techniques. A total of 93 water samples from different small communities of Chaco were analyzed. E. coli was identified in 36 (38.7%) of the tested samples. Six strains isolated from different samples harbored the studied genes. Of these 6 isolates, 3 carried the aap gene, 2 the AA probe and the last one the combination of aap/aggR genes. The prevalence of E. coli isolates harboring enteroaggregative virulence genes in groundwater sources was 6.4%. This work represents the first contribution to the study of the presence and distribution of virulence genes of EAEC in groundwater sources in this region of Argentina.

[Presence of Helicobacter pylori in gastric biopsies and feces of pediatric patients with celiac disease]

BACKGROUND

Helicobacter pylori (H. pylori) is the main etiologic agent of chronic gastritis and it is an important cause of gastric damage. The celiac disease can affect the morphology and the function of the gastrointestinal tract from the stomach to the colon and it is frequently associated with chronic gastritis.

AIM

to assess the presence of H. pylori in gastric biopsies and in feces of pediatric patients with celiac disease and to relate it with the symptoms.

PATIENTS AND METHODS

Pediatric patients with celiac disease attending the Gastroenterology Service at the "Avelino Castelán" Hospital in Resistencia (Argentina) were included in the study. Gastric biopsies samples were obtained by endoscopy for histological studies, the symptoms and socio-epidemiological characteristics were recorded and the polimerase chain reaction(PCR) was applied in feces in order to detect the presence of H. pylori.

RESULTS

Thirty one patients with celiac disease were studied (16 female and 15 male; age range:1-14 years; median 6.7 years); 14 (45.2%) were positive for H. pylori in gastric biopsy and among them, only 2 (14.2%) were positive for H. pylori in stool samples. There were not significant differences between symptoms between H. pylori positive and negative patients.

CONCLUSION

45.2% of the patients with celiac disease were infected by H. pylori. There was no correlation between the frequencies of bacterial detection in feces and in gastric biopsies. The clinical manifestations of celiac disease did not increase in children infected with H. pylori.

[Antimicrobial resistance of bacteria causing diarrhea in children from Corrientes, Argentina]

In Corrientes (Argentina), from January 2004 to April 2005, fecal samples from under 5 years-old children with acute diarrhea were collected; the stool samples were cultured onto selective media, and those colonies suspected to be Salmonella, Vibrio, Aeromonas, Shigella, or Escherichia coli O157 were identified. The antimicrobial susceptibility was assessed by the disk diffusion method. Among 590 samples, the 7.7% were positive (Salmonella spp 32.6% and Shigella spp 67.4%). Of 31 Shigella isolates, 81% were S. flexneri, and 19% were S. sonnei. S. flexneri serotype 2 was the more frequent. S. flexneri strains showed higher multidrug resistance than S. sonnei strains. Among the Salmonella enterica serotypes, S. typhimurium and S. newport were the most frequent. Two isolates of Salmonella presented with multidrug resistance. This paper was a contribution to the knowledge of bacterial gastroenteritis etiology in our region and it called the attention to the emergence of multidrug-resistant enteropathogenic strains.

[Antibiotic resistance and molecular epidemiology of Shigella spp. in northeastern Argentina]

OBJECTIVES

To evaluate the antibiotic resistance of strains of Shigella spp. isolated from feces samples from northeastern Argentina and to characterize the strains in terms of their molecular epidemiology.

METHODS

We studied 132 isolates of Shigella spp. obtained from feces samples from 132 patients with diarrhea who were seen at various private and public laboratories in the Argentine provinces of Chaco and Corrientes during the period of 1998 to 2002. Each strain was characterized according to its serotype, its resistance to 13 individual or combination antibiotics, and its sensitivity to pyocins. With 52 strains selected in relation to their antimicrobial susceptibility profiles we conducted plasmid profile analysis using alkaline lysis, and the repetitive extragenic palindromic sequences were determined by amplifying repetitive DNA segments using polymerase chain reaction. The chi-square test was used to compare proportions, with a level of statistical significance of 0.05.

RESULTS

Shigella flexneri was the most common species (78%), followed by S. sonnei (22%). In general, the resistance of S. flexneri to the antibiotics studied was greater than that of S. sonnei, and this difference was statistically significant (P < 0.001) for ampicillin, tetracycline, chloramphenicol, and the combination of ampicillin and sulbactam. The S. flexneri strains also showed multiple resistance more often than S. sonnei strains (84.5% vs. 31.0%; P < 0.001). The strains isolated from S. flexneri were grouped into five pyocin types, three plasmid profiles, and five patterns of repetitive palindromic sequences. The strains of S. sonnei formed three pyocin types, two plasmid profiles, and three patterns of repetitive palindromic sequences.

CONCLUSIONS

Given that the Shigella species that were studied showed a high level of resistance to the most frequently used antibiotics, surveillance activities should be implemented in order to detect and control the appearance of new resistant strains. Applying epidemiological typing techniques can provide more precise information about the distribution and evolution of resistant strains of circulating microorganisms.

Analysis of the clonal relationship among clinical isolates of Salmonella enterica serovar Infantis by different typing methods

Salmonella Infantis has been the second most common serovar in Argentina in the last two years, being isolated mostly from paediatric hospitalised patients. In order to determine the clonal relationship among Salmonella Infantis strains, we examined 15 isolates from paediatric patient faeces in Argentina (12 geographically related and 3 geographically non-related) by using antimicrobial susceptibility, plasmid profiling, repetitive extragenic palindromic (REP) PCR, enterobacterial repetitive intergenic consensus (ERIC) PCR, and low-frequency restriction analysis of chromosomal DNA by pulsed field gel electrophoresis (PFGE). Four Spanish strains were included as controls of clonal diversity in molecular techniques. Antibiotype and plasmid profile was not useful as epidemiological tools. PFGE and REP-PCR were able to discriminate between Argentinean and Spanish isolates of Salmonella Infantis allowing to detect genetically related strains in three different cities. This finding indicates that a possible spread of a clone of this serovar in the North-eastern Region of Argentina has taken place in 1998.

[Prevalence of Enterococcus faecalis and Enterococcus faecium with high resistance to aminoglycosides in the cities of Resistencia and Corrientes, Republic of Argentina]

BACKGROUND

The objective of this study was characterize the prevalence of high-level aminoglycosides resistance (HLRA) in Enterococcus faecalis and E. faecium, determine the relationship between high-level gentamicin resistance (HLGR) and other aminoglycosides, and their distribution according clinical samples (blood, urine and others).

MATERIALS AND METHOD

A total of 177 strain (157 E. faecalis and 20 E. faecium) isolated from 1996 to 1998 were studied. They were identified by using classic methods. Their susceptibility to gentamicin, streptomycin, and kanamycin was tested by the disk diffusion technique using high-level disks in agar Müller Hinton.

RESULTS

E. faecalis showed HLRG of 28.7%, streptomycin 28.7% and kanamycin 37.6%, E. faecium showed 50%, 40%, and 60% respectively. The strains with HLRA have a tendency to high-level resistances to streptomycin and kanamycin (p < 0.0005). Statistical analysis demonstrated significative differences among strains with HLRA isolated from blood, urine and other clinical samples (p < 0.0005 to gentamicin and streptomycin and 0.004 < p < 0.007 to kanamycin).

CONCLUSIONS

The prevalence of HLRA enterococci found in the area os this study, justify its detection, particularity in cases of serious infections.

[Value of antibiotype and bacteriocinotype for differentiating Shigella strains isolated in Argentina]

The aim of the present work was to analyse the phenotypical characteristics of Shigella strains in order to evaluate their possible utilisation as epidemiological markers. For one year, we studied 95 strains of Shigella obtained from stool specimens of patients with dysentery. Bacteria came from various health care centres in the states of Chaco and Corrientes (Argentina). Bacteria were identified by using classical biochemical methods. All strains were serotyped and susceptibility patterns were determined using thirteen antibiotics. Bacteriocin typing was determined by the sensitivity to piocins of Pseudomonas aeruginosa and to marcescins of Serratia marcescens. Colicin production in S. sonnei was also studied. Among all the strains examined, the most prevalent was Shigella flexneri (82%) followed by Shigella sonnei (18%). The most frequent serotype among S. flexneri was 2 (93%), followed by serotypes 6 (4%), 1 (1.5%), and 3 (1.5%). S. sonnei strains were classified in 7 antibiotypes, 6 piocin types, 3 marcescin types, and 4 colicin types. Strains of S. flexneri type 2 were divided among 14 antibiotypes, 4 piocin types and 2 marcescin types. Simpson's index of diversity was applied to evaluate the discriminatory power of studied typing methods, both alone and combined. Our results indicate that when taken independently, none of the evaluated typing methods had discriminative power, but when taken together, they may be successfully used for the epidemiological typing of Shigella strains.

[Non-fermenting Gram-negative bacilli: distribution in clinical specimens and antimicrobial susceptibility]

In the present work was studied the prevalence, distribution in clinical specimens, and antimicrobial susceptibility of non-fermentative Gram-negative bacilli (NFGNB) from patients attended at Hospital "Angela I. de Llano" (Corrientes, Argentina). A total of 125 strains of NFGNB were recovered from various clinical specimens from July, 1997 to December, 1998. Isolates were identified by classical biochemical tests. Drug sensitivity was performed by standard methods with cefotaxime (CTX), ceftazidime (CAZ), piperacillin (PIP), ampicillin-sulbactam (AMS), piperacillin/tazobactam (TAZ), imipenem (IMP), amikacin (AKN), gentamicin (GEN) and ciprofloxacin (CIP). The most common isolates were Pseudomonas aeruginosa (48.8%); Acinetobacter baumannii (16.8%), Acinetobacter spp. (6.4%), Chryseobacterium spp. (5.6%), Stenotrophomonas maltophilia (4%), and others (18.4%). Most of them were recovered from respiratory secretions (36.0%), and urine (26.4%). IMP was the most effective antimicrobial. Many species of NFGNB showed resistance to several antibiotics tested (CTX, GEN, AMS, and CIP). Due to multiresistance found by more prevalent NFGNB, constant survey of antibacterial sensibility are essential for a correct control and management of nosocomial infections, and ambulatory patients with some risk factors.

[Mouth colonization by Streptococcus pyogenes in patients with impetigo]

The faucial carrying of Streptococcus pyogenes in patients presenting impetigo was determined as a risk factor for non-suppurative complications (acute glomerulonephritis). The fauces cultures of these patients revealed a S. pyogenes colonization of 65% and all the isolates were penicillin-sensitive. It was concluded that the high percent of faucial colonization made a systemic antimicrobial treatment necessary.