Antimicrobial resistances do not affect colonization parameters of intestinal E. coli in a small piglet group. - Related Documents




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472101.0000Antimicrobial resistances do not affect colonization parameters of intestinal E. coli in a small piglet group. BACKGROUND: Although antimicrobial resistance and persistence of resistant bacteria in humans and animals are major health concerns worldwide, the impact of antimicrobial resistance on bacterial intestinal colonization in healthy domestic animals has only been rarely studied. We carried out a retrospective analysis of the antimicrobial susceptibility status and the presence of resistance genes in intestinal commensal E. coli clones from clinically healthy pigs from one production unit with particular focus on effects of pheno- and/or genotypic resistance on different nominal and numerical intestinal colonization parameters. In addition, we compared the occurrence of antimicrobial resistance phenotypes and genotypes with the occurrence of virulence associated genes typical for extraintestinal pathogenic E. coli. RESULTS: In general, up to 72.1% of all E. coli clones were resistant to ampicillin, chloramphenicol, kanamycin, streptomycin, sulfamethoxazole or tetracycline with a variety of different resistance genes involved. There was no significant correlation between one of the nominal or numerical colonization parameters and the absence or presence of antimicrobial resistance properties or resistance genes. However, there were several statistically significant associations between the occurrence of single resistance genes and single virulence associated genes. CONCLUSION: The demonstrated resistance to the tested antibiotics might not play a dominant role for an intestinal colonization success in pigs in the absence of antimicrobial drugs, or cross-selection of other colonization factors e.g. virulence associated genes might compensate "the cost of antibiotic resistance". Nevertheless, resistant strains are not outcompeted by susceptible bacteria in the porcine intestine.200919814790
457210.9999Effect of high pressure processing on changes in antibiotic resistance genes expression among strains from commercial starter cultures. This study analyzed the effect of high-pressure processing on the changes in resistance phenotype and expression of antibiotic resistance genes among strains from commercial starter cultures. After exposure to high pressure the expression of genes encoding resistance to aminoglycosides (aac(6')Ie-aph(2″)Ia and aph(3')-IIIa) decreased and the expression of genes encoding resistance to tetracyclines (tetM and tetW), ampicillin (blaZ) and chloramphenicol (cat) increased. Expression changes differed depending on the pressure variant chosen. The results obtained in the gene expression analysis correlated with the results of the phenotype patterns. To the best of the authors' knowledge, this is one of the first studies focused on changes in antibiotic resistance associated with a stress response among strains from commercial starter cultures. The results suggest that the food preservation techniques might affect the phenotype of antibiotic resistance among microorganisms that ultimately survive the process. This points to the need to verify strains used in the food industry for their antibiotic resistance as well as preservation parameters to prevent the further increase in antibiotic resistance in food borne strains.202336462825
490720.9999Mathematical model of plasmid-mediated resistance to ceftiofur in commensal enteric Escherichia coli of cattle. Antimicrobial use in food animals may contribute to antimicrobial resistance in bacteria of animals and humans. Commensal bacteria of animal intestine may serve as a reservoir of resistance-genes. To understand the dynamics of plasmid-mediated resistance to cephalosporin ceftiofur in enteric commensals of cattle, we developed a deterministic mathematical model of the dynamics of ceftiofur-sensitive and resistant commensal enteric Escherichia coli (E. coli) in the absence of and during parenteral therapy with ceftiofur. The most common treatment scenarios including those using a sustained-release drug formulation were simulated; the model outputs were in agreement with the available experimental data. The model indicated that a low but stable fraction of resistant enteric E. coli could persist in the absence of immediate ceftiofur pressure, being sustained by horizontal and vertical transfers of plasmids carrying resistance-genes, and ingestion of resistant E. coli. During parenteral therapy with ceftiofur, resistant enteric E. coli expanded in absolute number and relative frequency. This expansion was most influenced by parameters of antimicrobial action of ceftiofur against E. coli. After treatment (>5 weeks from start of therapy) the fraction of ceftiofur-resistant cells among enteric E. coli, similar to that in the absence of treatment, was most influenced by the parameters of ecology of enteric E. coli, such as the frequency of transfer of plasmids carrying resistance-genes, the rate of replacement of enteric E. coli by ingested E. coli, and the frequency of ceftiofur resistance in the latter.201222615803
472330.9999Impact of Sublethal Disinfectant Exposure on Antibiotic Resistance Patterns of Pseudomonasaeruginosa. OBJECTIVE: The problem of hospital cross-infection due to contamination of disinfectants has been recognized elsewhere. The passage of bacteria through diluted disinfectants may not only bring about phenotypic changes in their antibiograms but also changes in phage susceptibility patterns. Contact with disinfectants in sublethal concentrations allows survival and multiplication of bacteria. METHODS AND MATERIALS: Serial passage, through disinfectants at subminimal inhibitory concentrations, induced antibiotic resistance in 18% of derived phenotypic variants of fifty strains of Pseudomonas aeruginosa which were isolated from diarrheal stools of infants in children's hospital. RESULTS: A proportion of these strains became susceptible to an increased number of antibiotics. The present study revealed that all the isolates were resistant to tetracycline and carbenicillin and 40% of these isolates became sensitive to both antibiotics after exposure to disinfectants. The exposure to disinfectants induced neomycin resistance among two isolates. The resistance patterns were three before disinfectants exposure which increased to be nine different patterns after exposure. No antibiotic resistance was transferred between P. aeruginosa and Escherichia coli K12 as a recipient strain. CONCLUSIONS: Almost 50% of the isolates tested became sensitive to tetracycline, carbenicillin and co-trimoxazole after exposure to disinfectants. The resistance patterns among the 50 isolates were three which changed to be nine different patterns after exposure to disinfectants. Unjustifiable use of disinfectants might give a chance for survival and multiplication of pathogenic bacteria to develop new resistance patterns to antibiotics in use with a short time. These new resistance variants of bacteria which multiply in hospital environment could lead to serious epidemic conflicts particularly the epidemiological reporting and management. OBJECTIVE: The problem of hospital cross-infection due to contamination of disinfectants has been recognized elsewhere. The passage of bacteria through diluted disinfectants may not only bring about phenotypic changes in their antibiograms but also changes in phage susceptibility patterns. Contact with disinfectants in sublethal concentrations allows survival and multiplication of bacteria. METHODS AND MATERIALS: Serial passage, through disinfectants at subminimal inhibitory concentrations, induced antibiotic resistance in 18% of derived phenotypic variants of fifty strains of Pseudomonas aeruginosa which were isolated from diarrheal stools of infants in children's hospital. RESULTS: A proportion of these strains became susceptible to an increased number of antibiotics. The present study revealed that all the isolates were resistant to tetracycline and carbenicillin and 40% of these isolates became sensitive to both antibiotics after exposure to disinfectants. The exposure to disinfectants induced neomycin resistance among two isolates. The resistance patterns were three before disinfectants exposure which increased to be nine different patterns after exposure. No antibiotic resistance was transferred between P. aeruginosa and Escherichia coli K12 as a recipient strain. CONCLUSIONS: Almost 50% of the isolates tested became sensitive to tetracycline, carbenicillin and co-trimoxazole after exposure to disinfectants. The resistance patterns among the 50 isolates were three which changed to be nine different patterns after exposure to disinfectants. Unjustifiable use of disinfectants might give a chance for survival and multiplication of pathogenic bacteria to develop new resistance patterns to antibiotics in use with a short time. These new resistance variants of bacteria which multiply in hospital environment could lead to serious epidemic conflicts particularly the epidemiological reporting and management.202539536720
458040.9999Antimicrobial resistance of bacteria isolated from slaughtered and retail chickens in South Africa. Animal feed is increasingly being supplemented with antibiotics to decrease the risk of epidemics in animal husbandry. This practice could lead to the selection for antibiotic resistant micro-organisms. The aim of this study was to determine the level of antibiotic resistant bacteria present on retail and abattoir chicken. Staphylococci, Enterobacteriaceae, Salmonella and isolates from total aerobic plate count were tested for resistance to vancomycin, streptomycin, methicillin, tetracycline and gentamicin using the disc diffusion susceptibility test; resistance to penicillin was determined using oxacillin. Results from the antibiotic code profile indicated that many of the bacterial strains were displaying multiple antibiotic resistance (MAR). A larger proportion of resistance to most antibiotics, except for vancomycin, was displayed by the abattoir samples, therefore suggesting that the incidence of MAR pathogenic bacteria was also higher in the abattoir samples. This resistance spectrum of abattoir samples is a result of farmers adding low doses of antibiotics to livestock feed to improve feeding efficiency so that the animals need less food to reach marketable weight. The lower incidence of MAR pathogenic bacteria in the retail samples is a result of resistance genes being lost due to lack of selective pressure, or to the fact that the resistant flora are being replaced by more sensitive flora during processing. The use of subtherapeutic levels of antibiotics for prophylaxis and as growth promoters remains a concern as the laws of evolution dictate that microbes will eventually develop resistance to practically any antibiotic. Selective pressure exerted by widespread antimicrobial use is therefore the driving force in the development of antibiotic resistance. This study indicated that a large proportion of the bacterial flora on fresh chicken is resistant to a variety of antibiotics, and that resultant food-related infections will be more difficult to treat.19989633089
490850.9999Low temperatures do not impair the bacterial plasmid conjugation on poultry meat. Conjugation plays an important role in the dissemination of antimicrobial resistance genes. Besides, this process is influenced by many biotic and abiotic factors, especially temperature. This study aimed to investigate the effect of different conditions of temperature and storage (time and recipient) of poultry meat, intended for the final consumer, affect the plasmid transfer between pathogenic (harboring the IncB/O-plasmid) and non-pathogenic Escherichia coli organisms. The determination of minimal inhibitory concentrations (MIC) of ampicillin, cephalexin, cefotaxime, and ceftazidime was performed before and after the conjugation assay. It was possible to recover transconjugants in the poultry meat at all the treatments, also these bacteria showed a significant increase of the MIC for all antimicrobials tested. Our results show that a non-pathogenic E. coli can acquire an IncB/O-plasmid through a conjugation process in poultry meat, even stored at low temperatures. Once acquired, the resistance genes endanger public health especially when it is about critically and highly important antimicrobials to human medicine.202438191970
340260.9998Antibiotic resistance, virulence factors and biofilm formation ability in Escherichia coli strains isolated from chicken meat and wildlife in the Czech Republic. Attachment of pathogenic bacteria to food contact surfaces and the subsequent biofilm formation represent a serious threat for the food industry, since these bacteria are more resistant to antimicrobials or possess more virulence factors. The main aim of this study was to investigate the correlation between antibiotic resistance against 13 antibiotics, distribution of 10 virulence factors and biofilm formation in 105 Escherichia coli strains according to their origin. The high prevalence of antibiotic resistance that we have found in wildlife isolates could be acquired by horizontal transfer of resistance genes from human or domestic or farm animals. Consequently, these commensal bacteria might serve as indicator of antimicrobial usage for human and veterinary purposes in the Czech Republic. Further, 46 out of 66 resistant isolates (70%) were able to form biofilm and we found out statistically significant correlation between prevalence of antibiotic resistance and biofilm formation ability. The highest prevalence of antibiotic resistance was observed in weak biofilm producers. Biofilm formation was not statistically associated with any virulence determinant. However, we confirmed the correlation between prevalence of virulence factors and host origin. Chicken isolates possessed more virulence factors (66%), than isolates from wildlife (37%). We can conclude that the potential spread of antibiotic resistance pattern via the food chain is of high concern for public health. Even more, alarming is that E. coli isolates remain pathogenic potential with ability to form biofilm and these bacteria may persist during food processing and consequently lead to greater risks of food contamination.201728494209
467870.9998Antimicrobial Susceptibility of Lactic Acid Bacteria Strains of Potential Use as Feed Additives - The Basic Safety and Usefulness Criterion. The spread of resistance to antibiotics is a major health concern worldwide due to the increasing rate of isolation of multidrug resistant pathogens hampering the treatment of infections. The food chain has been recognized as one of the key routes of antibiotic resistant bacteria transmission between animals and humans. Considering that lactic acid bacteria (LAB) could act as a reservoir of transferable antibiotic resistance genes, LAB strains intended to be used as feed additives should be monitored for their safety. Sixty-five LAB strains which might be potentially used as probiotic feed additives or silage inoculants, were assessed for susceptibility to eight clinically relevant antimicrobials by a minimum inhibitory concentration determination. Among antimicrobial resistant strains, a prevalence of selected genes associated with the acquired resistance was investigated. Nineteen LAB strains displayed phenotypic resistance to one antibiotic, and 15 strains were resistant to more than one of the tested antibiotics. The resistance to aminoglycosides and tetracyclines were the most prevalent and were found in 37 and 26% of the studied strains, respectively. Phenotypic resistance to other antimicrobials was found in single strains. Determinants related to resistance phenotypes were detected in 15 strains as follows, the aph(3″)-IIIa gene in 9 strains, the lnu(A) gene in three strains, the str(A)-str(B), erm(B), msr(C), and tet(M) genes in two strains and the tet(K) gene in one strain. The nucleotide sequences of the detected genes revealed homology to the sequences of the transmissible resistance genes found in lactic acid bacteria as well as pathogenic bacteria. Our study highlights that LAB may be a reservoir of antimicrobial resistance determinants, thus, the first and key step in considering the usefulness of LAB strains as feed additives should be an assessment of their antibiotic resistance. This safety criterion should always precede more complex studies, such as an assessment of adaptability of a strain or its beneficial effect on a host. These results would help in the selection of the best LAB strains for use as feed additives. Importantly, presented data can be useful for revising the current microbiological cut-off values within the genus Lactobacillus and Pediococcus.202134277757
360680.9998Presence of specific antibiotic (tet) resistance genes in infant faecal microbiota. The widespread use of antibiotics for medical and veterinary purposes has led to an increase of microbial resistance. The antibiotic resistance of pathogenic bacteria has been studied extensively. However, antibiotics are not only selective for pathogens: they also affect all members of the gut microbiota. These microorganisms may constitute a reservoir of genes carrying resistance to specific antibiotics. This study was designed to characterize the gut microbiota with regard to the presence of genes encoding tetracycline resistance proteins (tet) in the gut of healthy exclusively breast-fed infants and their mothers. For this purpose we determined the prevalence of genes encoding ribosomal protection proteins (tet M, tet W, tet O, tet S, tet T and tet B) by PCR and characterized the gut microbiota by FISH in stools of infants and their mothers. The gene tet M was found in all the breast-fed infants and their mothers. tet O was found in all of the mothers' samples, whilst only 35% of the infants harboured this gene. tet W was less frequently found (85% of the mothers and 13% of the infants). None of the other genes analysed was found in any sample. Our results suggest that genes carrying antibiotic resistance are common in the environment, as even healthy breast-fed infants with no direct or indirect previous exposure to antibiotics harbour these genes.200616965348
339890.9998Ubiquity of R factor-mediated antibiotic resistance in the healthy population. An attempt was made to assess the occurrence of R factor-mediated antibiotic resistance in the healthy population. Samples of aerobic, gram-negative intestinal bacteria from men from various parts of the country at military conscription were analysed for transferable drug resistance. The obtained frequency, about 15% of R factor carriers in the studied group, was interpreted to reflect the existence of a reservoir of R factors, from which resistant, pathogenic bacteria could be selected under antibiotic therapy. Resistance to tetracycline, streptomycin and sulfonamides dominated among the identified R factor-borne resistance traits.1977320655
4722100.9998Ciprofloxacin, amoxicillin, and aminoglycosides stimulate genetic and phenotypic changes in uropathogenic Escherichia coli strains. Antibiotic therapy and its consequences in bacterial and human aspects are widely investigated. Despite this, the emergence of new multidrug resistant bacteria is still a current problem. The scope of our work included the observation of changes among uropathogenic Escherichia coli strains after the treatment with a subinhibitory concentration of different antibiotics. The sensitive strains with or without virulence factors were incubated with amoxicillin, ciprofloxacin, gentamycin, or tobramycin. After each passage, the E. coli derivatives were compared to their wild types based on their susceptibility profiles, virulence genes, biofilm formations and the fingerprint profiles of PCR products amplified with using the (N)(6)(CGG)(4) primer. It turned out that antibiotics caused significant changes in the repertoire of bacterial virulence and biofilm formation, corresponding to acquired cross-resistance. The genomic changes among the studied bacteria were reflected in the changed profiles of the CGG-PCR products. In conclusion, the inappropriate application of antibiotics may cause a rapid rise of Multidrug Resistant (MDR) strains and give bacteria a chance to modulate their own pathogenicity. This phenomenon has been easily observed among uropathogenic E. coli strains and it is one of the main reasons for recurrent infections of the urinary tract.201930938219
4581110.9998Development of aminoglycoside and β-lactamase resistance among intestinal microbiota of swine treated with lincomycin, chlortetracycline, and amoxicillin. Lincomycin, chlortetracycline, and amoxicillin are commonly used antimicrobials for growth promotion and infectious disease prophylaxis in swine production. In this study, we investigated the shifts and resistance development among intestinal microbiota in pregnant sows before and after lincomycin, chlortetracycline, and amoxicillin treatment by using phylogenetic analysis, bacterial enumeration, and PCR. After the antimicrobial treatment, shifts in microbial community, an increased proportion of resistant bacteria, and genes related to antimicrobial resistance as compared to the day before antimicrobial administration (day 0) were observed. Importantly, a positive correlation between antimicrobial resistance gene expression in different categories, especially those encoding aminoglycoside and β-lactamase and antimicrobial resistance, was observed. These findings demonstrate an important role of antimicrobial usage in animals in the development of antimicrobial resistance, and support the notion that prudent use of antimicrobials in swine is needed to reduce the risk of the emergence of multi-drug resistant zoonotic pathogens.201425408688
3932120.9998Acquired antibiotic resistance: are we born with it? The rapid emergence of antibiotic resistance (AR) is a major public health concern. Recent findings on the prevalence of food-borne antibiotic-resistant (ART) commensal bacteria in ready-to-consume food products suggested that daily food consumption likely serves as a major avenue for dissemination of ART bacteria from the food chain to human hosts. To properly assess the impact of various factors, including the food chain, on AR development in hosts, it is important to determine the baseline of ART bacteria in the human gastrointestinal (GI) tract. We thus examined the gut microbiota of 16 infant subjects, from the newborn stage to 1 year of age, who fed on breast milk and/or infant formula during the early stages of development and had no prior exposure to antibiotics. Predominant bacterial populations resistant to several antibiotics and multiple resistance genes were found in the infant GI tracts within the first week of age. Several ART population transitions were also observed in the absence of antibiotic exposure and dietary changes. Representative AR gene pools including tet(M), ermB, sul2, and bla(TEM) were detected in infant subjects. Enterococcus spp., Staphylococcus spp., Klebsiella spp., Streptococcus spp., and Escherichia coli/Shigella spp. were among the identified AR gene carriers. ART bacteria were not detected in the infant formula and infant foods examined, but small numbers of skin-associated ART bacteria were found in certain breast milk samples. The data suggest that the early development of AR in the human gut microbiota is independent of infants' exposure to antibiotics but is likely impacted by exposure to maternal and environmental microbes during and after delivery and that the ART population is significantly amplified within the host even in the absence of antibiotic selective pressure.201121821748
3395130.9998Presence of multidrug-resistant enteric bacteria in dairy farm topsoil. In addition to human and veterinary medicine, antibiotics are extensively used in agricultural settings, such as for treatment of infections, growth enhancement, and prophylaxis in food animals, leading to selection of drug and multidrug-resistant bacteria. To help circumvent the problem of bacterial antibiotic resistance, it is first necessary to understand the scope of the problem. However, it is not fully understood how widespread antibiotic-resistant bacteria are in agricultural settings. The lack of such surveillance data is especially evident in dairy farm environments, such as soil. It is also unknown to what extent various physiological modulators, such as salicylate, a component of aspirin and known model modulator of multiple antibiotic resistance (mar) genes, influence bacterial multi-drug resistance. We isolated and identified enteric soil bacteria from local dairy farms within Roosevelt County, NM, determined the resistance profiles to antibiotics associated with mar, such as chloramphenicol, nalidixic acid, penicillin G, and tetracycline. We then purified and characterized plasmid DNA and detected mar phenotypic activity. The minimal inhibitory concentrations (MIC) of antibiotics for the isolates ranged from 6 to >50 microg/mL for chloramphenicol, 2 to 8 microg/mL for nalidixic acid, 25 to >300 microg/mL for penicillin G, and 1 to >80 microg/mL for tetracycline. On the other hand, many of the isolates had significantly enhanced MIC for the same antibiotics in the presence of 5 mM salicylate. Plasmid DNA extracted from 12 randomly chosen isolates ranged in size from 6 to 12.5 kb and, in several cases, conferred resistance to chloramphenicol and penicillin G. It is concluded that enteric bacteria from dairy farm topsoil are multidrug resistant and harbor antibiotic-resistance plasmids. A role for dairy topsoil in zoonoses is suggested, implicating this environment as a reservoir for development of bacterial resistance against clinically relevant antibiotics.200515778307
3938140.9998Human health hazards associated with the administration of antimicrobials to slaughter animals. Part II. An assessment of the risks of resistant bacteria in pigs and pork. Risks for the consumer regarding the acquisition of resistant bacteria and/or resistance genes via the consumption of pork are discussed. In general, Salmonella spp. and Escherichia coli that originate from animals do not easily transfer their resistance genes to the resident intestinal flora of humans. The prevalence of resistant E. coli in humans seems more associated with being a vegetarian (odds ratio (OR) 1.89) than with the consumption of meat and meat products. Other risk factors are treatment with antimicrobials (OR 2-5), becoming hospitalized (OR 5.93), or working in a health setting (OR 4.38). In the Netherlands, annually an estimated 45,000 people (0-150,000) become a carrier of resistant E. coli and/or resistance genes that ori ginate from pigs, while an estimated 345,000 persons (175,000-600,000) become a carrier of resistant E. coli and/or resistance genes that originate from hospitals, e.g. other patients. Any problems with resistant Salmonella spp. that stem from pigs are, in fact, an integral part of the total problem of food-borne salmonellosis. Sometimes there are outbreaks of a specific multi-resistant clone of S. typhimurium that causes problems in both farm animals and humans. The probability that in the next 30 years there is no or maximally one outbreak of a specific clone that originates from pig herds is estimated at about 75%. Antimicrobials used as a growth promoter can have a measurable influence on the prevalence of resistant bacteria. The likely chain of events regarding avoparcin and the selection and dissemination of resistance against vancomycin in the enterococci gives the impression that the impact of the use of antimicrobials in animals on the prevalence of resistance in humans is largely determined by whether resistance genes are, or become, located on a self-transferable transposon. Furthermore, consumer health risks of antimicrobials used in slaughter pigs are mainly determined by the selection and dissemination of bacterial resistance and much less by the toxicological properties of any residues in pork. It is also concluded that most of the problems with resistant bacteria in humans are associated with the medical use of antimicrobials, and that the impact of particularly the veterinary use of antimicrobials is limited. However, the impact of antimicrobials used as a feed additive appears to be much greater than that of antimicrobials used for strictly veterinary purposes. The use of antimicrobials as a feed additive should therefore be seriously reconsidered.200111205995
3400150.9998Chicken liver is a potential reservoir of bacteriophages and phage-derived particles containing antibiotic resistance genes. Poultry meat production is one of the most important agri-food industries in the world. The selective pressure exerted by widespread prophylactic or therapeutic use of antibiotics in intensive chicken farming favours the development of drug resistance in bacterial populations. Chicken liver, closely connected with the intestinal tract, has been directly involved in food-borne infections and found to be contaminated with pathogenic bacteria, including Campylobacter and Salmonella. In this study, 74 chicken livers, divided into sterile and non-sterile groups, were analysed, not only for microbial indicators but also for the presence of phages and phage particles containing antibiotic resistance genes (ARGs). Both bacteria and phages were detected in liver tissues, including those dissected under sterile conditions. The phages were able to infect Escherichia coli and showed a Siphovirus morphology. The chicken livers contained from 10(3) to 10(6) phage particles per g, which carried a range of ARGs (bla(TEM) , bla(CTx-M-1) , sul1, qnrA, armA and tetW) detected by qPCR. The presence of phages in chicken liver, mostly infecting E. coli, was confirmed by metagenomic analysis, although this technique was not sufficiently sensitive to identify ARGs. In addition, ARG-carrying phages were detected in chicken faeces by qPCR in a previous study of the group. Comparison of the viromes of faeces and liver showed a strong coincidence of species, which suggests that the phages found in the liver originate in faeces. These findings suggests that phages, like bacteria, can translocate from the gut to the liver, which may therefore constitute a potential reservoir of antibiotic resistance genes.202235485188
4650160.9998Co-occurrence of resistance to different antibiotics among aquatic bacteria. BACKGROUND: Antibiotic resistance is not confined to pathogens, but is also widespread in various natural environments. In nature the microbes producing antibiotic compounds have been around for millions of years. Heavy use of antibiotics in medicine and veterinary practice may lead to the accumulation of resistance genes in microbial populations, followed by a rise in multiresistant bacteria. RESULTS: To test the extent of resistance among aquatic bacteria, we have collected 760 isolates resistant to at least one antibiotic. The phylogeny of the isolates covers a wide range of Proteobacteria, Actinobacteria and Bacteroidetes. In order to determine the extent of multiresistance, the isolates were tested on six antibiotics. As the growth rate of the different bacteria was highly variable, the classical medical resistance tests could not be used, and an alternative method considering the full growth curve was developed. In general, the overall resistances to different antibiotics could be explained by random, independent distribution. An exception to this was the resistances against tetracycline and chloramphenicol, which tended to occur in pairs. CONCLUSIONS: We conclude that there is no massive spread of multiresistance determinants in the studied environment, although some specific cases can be found, awaiting for molecular characterization of the resistance mechanisms.201223031674
3401170.9998Heavy metal resistance and virulence profile in Pseudomonas aeruginosa isolated from Brazilian soils. Pseudomonas aeruginosa is an opportunistic pathogen, which can have several virulence factors that confer on it the ability to cause severe, acute and chronic infections. Thus, the simultaneous occurrence of resistance to antibiotics and heavy metals associated with the presence of virulence genes is a potential threat to human health and environmental balance. This study aimed to investigate the resistance profile to heavy metals and the correlation of this phenotype of resistance to antimicrobials and to investigate the pathogenic potential of 46 P. aeruginosa isolates obtained from the soil of five Brazilian regions. The bacteria were evaluating for antimicrobial and heavy metal resistance, as well as the presence of plasmids and virulence genes. The isolates showed resistance to four different antibiotics and the majority (n = 44) had resistance to aztreonam or ticarcillin, furthermore, 32 isolates showed concomitant resistance to both of these antibiotics. A high prevalence of virulence genes was found, which highlights the pathogenic potential of the studied environmental isolates. Moreover, a high frequency of heavy metal resistance genes was also detected, however, the phenotypic results indicated that other genes and/or mechanisms should be related to heavy metal resistance.201627197940
3937180.9998Design of a system for monitoring antimicrobial resistance in pathogenic, zoonotic and indicator bacteria from food animals. DANMAP is a Danish programme for integrated monitoring of and research on antimicrobial resistance in bacteria from food animals, food and humans. The paper describes how bacteria from broilers, pigs, and cattle are collected, as well as the procedures for data handling and presentation of results. The bacteria from animals include certain pathogens, selected so that they are representative for submissions to Danish diagnostic laboratories, as well as zoonotic bacteria (Campylobacter, Salmonella and Yersinia) and indicator bacteria (E. coli, E. faecium and E. faecalis), from samples collected at abattoirs. The latter samples are selected so that they are representative of the respective animal populations. Therefore, the apparent prevalence of antimicrobial resistance in the populations may be calculated. The isolates are identified to species level and the results of susceptibility testing are stored as continuous variables. All isolates are maintained in a strain collection so that they are available for subsequent research projects. The data handling facilities makes it possible to present results as percent resistant isolates or as the apparent prevalence of resistance in the population, or alternatively as graphical distributions of mm inhibition zones or MIC values. Computer routines have been established that make it possible to detect specific phenotypic expressions of resistance that may be of particular interest.199910783720
4909190.9998In vitro digestion of ESC-resistant Escherichia coli from poultry meat and evaluation of human health risk. INTRODUCTION: The spread of antimicrobial resistance (AMR) has become a threat against human and animal health. Third and fourth generation cephalosporins have been defined as critically important antimicrobials by The World Health Organization. Exposure to Extended spectrum cephalosporin-resistant E. coli may result in consumers becoming carriers if these bacteria colonize the human gut or their resistance genes spread to other bacteria in the gut microbiota. In the case that these resistant bacteria at later occasions cause disease, their resistance characteristics may lead to failure of treatment and increased mortality. We hypothesized that ESC-resistant E. coli from poultry can survive digestion and thereby cause infections and/or spread their respective resistance traits within the gastro-intestinal tract. METHODS: In this study, a selection of 31 ESC-resistant E. coli isolates from retail chicken meat was exposed to a static in vitro digestion model (INFOGEST). Their survival, alteration of colonizing characteristics in addition to conjugational abilities were investigated before and after digestion. Whole genome data from all isolates were screened through a custom-made virulence database of over 1100 genes for virulence- and colonizing factors. RESULTS AND DISCUSSION: All isolates were able to survive digestion. Most of the isolates (24/31) were able to transfer their bla (CMY2)-containing plasmid to E. coli DH5-á, with a general decline in conjugation frequency of digested isolates compared to non-digested. Overall, the isolates showed a higher degree of cell adhesion than cell invasion, with a slight increase after digestion compared non-digested, except for three isolates that displayed a major increase of invasion. These isolates also harbored genes facilitating invasion. In the virulence-associated gene analysis two isolates were categorized as UPEC, and one isolate was considered a hybrid pathogen. Altogether the pathogenic potential of these isolates is highly dependent on the individual isolate and its characteristics. Poultry meat may represent a reservoir and be a vehicle for dissemination of potential human pathogens and resistance determinants, and the ESC-resistance may complicate treatment in the case of an infection.202336846779