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PubMed2024

Contaminant-degrading bacteria are super carriers of antibiotic resistance genes in municipal landfills: A metagenomics-based study.

Municipal landfills are hotspot sources of antimicrobial resistance (AMR) and are also important habitats of contaminant-degrading bacteria. However, high diversity of antibiotic resistance genes (ARGs) in landfills hinders assessing AMR risks in the affected environment. More concerned, whether there is co-selection or enrichment of antibiotic-resistant bacteria and contaminant-degrading bacteria in these extremely polluted environments is far less understood. Here, we collected metagenomic datasets of 32 raw leachate and 45 solid waste samples in 22 municipal landfills of China. The antibiotic resistome, antibiotic-resistant bacteria and contaminant-degrading bacteria were explored, and were then compared with other environmental types. Results showed that the antibiotic resistome in landfills contained 1,403 ARG subtypes, with the total abundance over the levels in natural environments and reaching the levels in human feces and sewage. Therein, 49 subtypes were listed as top priority ARGs for future surveillance based on the criteria of enrichment in landfills, mobilizable and present in pathogens. By comparing to those in less contaminated river environments, we elucidated an enrichment of antibiotic-resistant bacteria with contaminant-degrading potentials in landfills. Bacteria in Pseudomonadaceae, Moraxellaceae, Xanthomonadaceae and Enterobacteriaceae deserved the most concerns since 72.2 % of ARG hosts were classified to them. Klebsiella pneumoniae, Acinetobacter nosocomialis and Escherichia coli were abundant multidrug-resistant pathogenic species in raw leachate (∼10.2 % of total microbiomes), but they rarely carried contaminant-degradation genes. Notably, several bacterial genera belonging to Pseudomonadaceae had the most antibiotic-resistant, pathogenic, and contaminant-degrading potentials than other bacteria. Overall, the findings highlight environmental selection for contaminant-degrading antibiotic-resistant pathogens, and provide significant insights into AMR risks in municipal landfills.

Metagenomics↗

PubMed2004

Risk analysis of drinking water microbial contamination versus disinfection by-products (DBPs).

Managing the provision of safe drinking water has a renewed focus in light of the new World Health Organization (WHO) water safety plans. Risk analysis is a necessary component to assist in selecting priority hazards and identifying hazardous scenarios, be they qualitative to quantitative assessments. For any approach, acute diarrhoeal pathogens are often the higher risk issue for municipal water supplies, no matter how health burden is assessed. Furthermore, potential sequellae (myocarditis, diabetes, reactive arthritis and cancers) only further increase the potential health burden of pathogens; despite the enormous uncertainties in determining pathogen exposures and chemical dose-responses within respective microbial and chemical analyses. These interpretations are currently being improved by Bayesian and bootstrapping approaches to estimate parameters for stochastic assessments. A case example, covering the health benefits of ozonation for Cryptosporidium inactivation versus potential cancers from bromate exposures, illustrated the higher risks from a pathogen than one of the most likely disinfection by-products (DBPs). Such analyses help justify the industries long-held view of the benefits of multiple barriers to hazards and that microbial contamination of water supplies pose a clear public health risk when treatment is inadequate. Therefore, efforts to reduce potential health risks from DBP must not compromise pathogen control, despite socio-political issues.

Carcinogens↗

PubMed2005

[Bacterial detection leading to pathogen inactivation].

Bacterial contamination of blood components remains the highest infectious risk in blood transfusion, the risk is particularly high when it affects platelet concentrates (PC). In France, the residual risk of transfusion reaction due to bacterial contamination of PC has been decreasing slowly since 1994 but for all severity 1 case occurs with about 25,000 distributed PC and one death occurs with 200,000 distributed units. This reduction of the risk may be due to the measures which were implemented during the last 10 years in order to prevent contamination during donation. Improving strategies for reducing the risks of bacterial contamination is one of the priorities of the French National Blood Transfusion Service (l'Etablissement Français du sang - EFS). The main target remains PC. Bacterial detection or pathogens inactivation are now available and are able to reduce (for detection) or prevent (for inactivation) the occurrence of reaction due to bacterial contamination of PC. Up to now, the choice is in favour of bacterial detection. A national study was carried out in seven regional EFS at the end of 2004. It aims at confirming the feasibility of a systematic bacterial screening of PC before their delivery. The first conclusions show that this screening can be implemented with acceptable modifications in term of platelets availability. We can expect in a next future that new pathogens reduction technique and/or new detection systems will be available, certainly more efficient to prevent reaction due to bacterial contamination. Implementation of actual detection methods is probably a temporary solution.

Bacteriological Techniques↗

PubMedDate not supplied

[Microbiological aspects of the environment of deep sea habitats].

It is known that the hyperbaric environment facilitates selection of gram-negative microorganisms which acquire ecological predominance. From this point of view deep sea habitats can be regarded as a specific anthropotechnological niche for pathogenic microorganisms, particularly Pseudomonas aeruginosa A. aeruginosa colonization of the mucosa and skin of deep sea divers may result in infection manifestations which took place in chamber experiments when test subjects showed otitis externa and when virulent strains were isolated. It was demonstrated that the basic reservoir of P. aeruginosa was the water supply system. Hence, development of a reliable method for its disinfection should be of highest priority. One of the potential methods is SHF treatment. Another important approach is personal hygiene procedures preventing skin and mucosa contamination with potentially pathogenic microorganisms and procedures for increasing colonization resistance of divers with the aid of eubiotic therapy.

Atmosphere Exposure Chambers↗

PubMed2000

[Bacterial resistance and implications for daily practice].

Present and future solutions to the problem of bacterial multiple resistance involve physicians, patients and veterinarians. Their behaviour should evolve to take into account the medical and economical issues of antibiotic prescription. The clinical diagnosis requires a more rigorous assessment, based on bacteriological and rapid antigenic tests. Vaccination in both young people and the elderly, is an essential prophylactic tool, which is too often neglected. When a bacterial infection is suspected or proven, priority should be given to a targeted antimicrobial therapy with a bactericidal activity, in order to quickly eradicate pathogens. Therapies should be shorter and questionable antibio-prophylaxis should also be avoided. A watch laboratory network should provide physicians with an adequate information on local bacterial resistance patterns on a regular basis, in order to allow them adjusting their prescription.

Anti-Bacterial Agents↗

PubMedDate not supplied

[Multiple bacterial resistance in daily practice].

Present and future solutions to the problem of bacterial multiple resistance involve physicians, patients and veterinarians. Their behaviour should evolve to take into account the medical and economical issues of antibiotic prescription. The clinical diagnosis requires a more rigorous assessment, based on bacteriological and rapid antigenic tests. Vaccination in both young people and the elderly, is an essential prophylactic tool, which is too often neglected. When a bacterial infection is suspected or proven, priority should be given to a targeted antimicrobial therapy with a bactericidal activity, in order to quickly eradicate pathogens. Therapies should be shorter and questionable antibioprophylaxis should also be avoided. A watch laboratory network should provide physicians with an adequate information on local bacterial resistance patterns on a regular basis, in order to allow them adjusting their prescription.

Bacterial Infections↗

PubMed2000

Vaccines against the avian enteropathogens Eimeria, Cryptosporidium and Salmonella.

The worldwide poultry industry provides a substantial proportion of the nutritional requirement of the human population. To keep pace with the increasing demand for the high-quality, low-cost protein source that poultry provides, intensive rearing practices have been developed within the past few decades. For example, chickens are housed routinely in crowded environments under adverse conditions, and genetic strains have been selected for rapid growth, high protein-to-fat content and superior egg-laying characteristics. A major negative consequence of these practices has been an increase in the incidence of diseases. Enteric diseases in particular have emerged as a major problem threatening the future viability of the poultry industry. A variety of methods have been used to combat avian diseases in the commercial setting, including improved farm management practices, the use of antibiotic drugs, the selection of disease-resistant strains of chickens, and the manipulation of the chicken's immune system. In the latter category, the development of vaccines against the major avian diseases has become a priority in the poultry industry. This review will highlight recent progress in vaccine development against three major avian enteric pathogens: Eimeria, Cryptosporidium and Salmonella.

Animal Husbandry↗

PubMed1993

Infection and autoimmunity as etiologic factors in schizophrenia: a review and reappraisal.

The focus of schizophrenia research has been turning from studies of structural and functional brain abnormalities to an increasing emphasis on possible etiologic factors. One etiologic hypothesis is that schizophrenia is the result of an infection (especially by a virus) or of an autoimmune reaction (perhaps following an infection) against central nervous system (CNS) tissue. Indirect evidence supporting this hypothesis includes possible geographic variance in the prevalence of schizophrenia, a season-of-birth effect, and observed associations between schizophrenia and prenatal exposure to viral epidemics. Several studies of cell-based and humoral immunity, as well as studies of cytokines, have indicated abnormalities in the immune function of schizophrenia patients, but many of these findings have not been replicated consistently. In addition, most observed alterations in immune function have been modest in degree and nonspecific. Attempts to identify a specific infectious agent or an antibody directed against CNS tissue have not produced a consistently replicable finding. In summary, no research evidence to date irrefutably indicates an infectious or autoimmune etiologic process in schizophrenia. It is probably unreasonable, however, to view schizophrenia as having a single cause. It is much more likely to be a heterogeneous disorder resulting from interactions between multiple factors, including the person's genetic endowment and various environmental influences. Infectious agents or CNS autoantibodies may well be among these environmental variables. A major current emphasis is on studying potential interactions between exposure to an infection or an autoimmune response and key early phases of brain development. A corresponding priority in the research agenda will be the development of animal models of CNS development that might elucidate the pathogenic mechanisms of such an interaction.

Autoimmunity↗

PubMed2006

The burden of rotavirus diarrhea in Khanh Hoa Province, Vietnam: baseline assessment for a rotavirus vaccine trial.

BACKGROUND: In Vietnam, rotavirus is seen as a priority disease because studies have demonstrated that >50% of children hospitalized for treatment of diarrhea have rotavirus as the pathogen. To anticipate the availability of new vaccines, we have examined our field area in Nha Trang, Khanh Hoa Province, Vietnam, as a potential site to conduct a field trial of a future rotavirus vaccine. METHODS: Data from a population census, incidence rates of diarrhea from a previous cholera vaccine trial and hospitalization rates from computerized records collected from the 2 main hospitals in the province were reviewed to estimate the burden of rotavirus-related diarrhea that might be expected during a field trial of a rotavirus vaccine. RESULTS: For a birth cohort of approximately 5000 children, we would expect approximately 2500 clinic visits and 650-850 hospitalizations for treatment of diarrhea, of which approximately 375-425 would be attributable to rotavirus. For the Vietnamese birth cohort of 1,639,000 children, these numbers translate into approximately 820,000 clinic visits, 122,000-140,000 hospitalizations and 2900-5400 deaths annually attributable to rotavirus-related diarrhea. CONCLUSIONS: Vietnam is an early adaptor of new vaccines, has high national coverage rates (>85%) for childhood immunization and receives international donor support for the introduction of new vaccines. We found the epidemiologic features of rotavirus in rural Vietnam to be more similar to those of rotavirus in a developed country than to those of rotavirus in India or Bangladesh.

Child, Preschool↗

PubMed2007

Inhibition of maize streak virus (MSV) replication by transient and transgenic expression of MSV replication-associated protein mutants.

Maize streak disease is a severe agricultural problem in Africa and the development of maize genotypes resistant to the causal agent, Maize streak virus (MSV), is a priority. A transgenic approach to engineering MSV-resistant maize was developed and tested in this study. A pathogen-derived resistance strategy was adopted by using targeted deletions and nucleotide-substitution mutants of the multifunctional MSV replication-associated protein gene (rep). Various rep gene constructs were tested for their efficacy in limiting replication of wild-type MSV by co-bombardment of maize suspension cells together with an infectious genomic clone of MSV and assaying replicative forms of DNA by quantitative PCR. Digitaria sanguinalis, an MSV-sensitive grass species used as a model monocot, was then transformed with constructs that had inhibited virus replication in the transient-expression system. Challenge experiments using leafhopper-transmitted MSV indicated significant MSV resistance--from highly resistant to immune--in regenerated transgenic D. sanguinalis lines. Whereas regenerated lines containing a mutated full-length rep gene displayed developmental and growth defects, those containing a truncated rep gene both were fertile and displayed no growth defects, making the truncated gene a suitable candidate for the development of transgenic MSV-resistant maize.

Gene Expression↗

PubMedDate not supplied

Selecting pumps for breastfeeding mothers.

By understanding how a breast pump works, the nurse can suggest a pump best suited to meet the needs of the mother and her infant. When the infant is well, issues of cost and convenience can be the priority; when the infant is ill, primary considerations are how negative pressure is created, maintained, and released and how pathogens are controlled. Understanding these mechanisms helps solve technical problems that contribute to malfunction or maternal discomfort.

Breast Feeding↗

PubMed2005

Shigellosis.

Shigellosis is a global human health problem. Four species of Shigella i.e. S. dysenteriae, S. flexneri, S. boydii and S. sonnei are able to cause the disease. These species are subdivided into serotypes on the basis of O-specific polysaccharide of the LPS. Shigella dysenteriae type 1 produces severe disease and may be associated with life-threatening complications. The symptoms of shigellosis include diarrhoea and/or dysentery with frequent mucoid bloody stools, abdominal cramps and tenesmus. Shigella spp. cause dysentery by invading the colonic mucosa. Shigella bacteria multiply within colonic epithelial cells, cause cell death and spread laterally to infect and kill adjacent epithelial cells, causing mucosal ulceration, inflammation and bleeding. Transmission usually occurs via contaminated food and water or through person-to-person contact. Laboratory diagnosis is made by culturing the stool samples using selective/differential agar media. Shigella spp. are highly fragile organism and considerable care must be exercised in collecting faecal specimens, transporting them to the laboratories and in using appropriate media for isolation. Antimicrobial agents are the mainstay of therapy of all cases of shigellosis. Due to the global emergence of drug resistance, the choice of antimicrobial agents for treating shigellosis is limited. Although single dose of norfloxacin and ciprofloxacin has been shown to be effective, they are currently less effective against S. dysenteriae type 1 infection. Newer quinolones, cephalosporin derivatives, and azithromycin are the drug of choice. However, fluoroquinolone-resistant S. dysenteriae type 1 infection have been reported. Currently, no vaccines against Shigella infection exist. Both live and subunit parenteral vaccine candidates are under development. Because immunity to Shigella is serotype-specific, the priority is to develop vaccine against S. dysenteriae type 1 and S. flexneri type 2a. Shigella species are important pathogens responsible for diarrhoeal diseases and dysentery occurring all over the world. The morbidity and mortality due to shigellosis are especially high among children in developing countries. A recent review of literature (Kotloff et al.,1999) concluded that, of the estimated 165 million cases of Shigella diarrhoea that occur annually, 99% occur in developing countries, and in developing countries 69% of episodes occur in children under five years of age. Moreover, of the ca.1.1 million deaths attributed to Shigella infections in developing countries, 60% of deaths occur in the under-five age group. Travellers from developed to developing regions and soldiers serving under field conditions are also at an increased risk to develop shigellosis.

Drug Resistance, Bacterial↗

PubMed1998

Control strategies for Marek's disease: a perspective for the future.

Marek's disease virus is an evolving pathogen, acquiring virulence in response to increasingly effective vaccines. Although vaccine efficacy is generally good, industry has placed a high priority on more effective products. The search for better vaccines has been conducted mainly in the arena of molecular biology, and has been thus far disappointing. Various conditions prevail that currently limit the potential to develop suitable long-term solutions. A new paradigm based on reduction of early exposure, multiple levels of host resistance, and improved cooperation among stakeholders is proposed for consideration.

Animals↗

PubMed2000

Controlling on-farm inventories of bulk-tank raw milk--an opportunity to protect public health.

Hazard Analysis Critical Control Point programs provide a systematic approach for the reduction of food safety problems through preventive measures. On-farm programs similar to Hazard Analysis Critical Control Point, which target pathogen reduction and screening can provide assurance to processors and consumers that on-farm food safety is a high priority. Additional voluntary oversight of farm practices, including monitoring of and controlled access to raw milk supplies on the farm could further contribute to public food safety. Off-farm sales of raw milk directly to the public have resulted in foodborne outbreaks of multidrug resistant salmonellosis in California and Washington when raw milk was used for unlicensed cheese production. If dairy producers in those cases had voluntary programs in place to inventory, monitor, and control access to raw milk supplies, the outbreaks probably could have been prevented.

Animals↗

PubMed2006

Microbial forensics for natural and intentional incidents of infectious disease involving animals.

Microbial forensics is a relatively new scientific discipline dedicated to analysing microbiological evidence from a crime for attribution purposes. It builds on traditional microbiology and epidemiology but within a legal framework. Important motives for forensic investigations include interdiction of criminals, prosecution of justice, and ideally, deterrence of others from committing similar acts. Forensic capabilities in animal health should focus on building capacity for detection and reporting of increases in infectious disease morbidity and mortality among animals that might reflect a covert release of a pathogen. Suspicion should be raised when epidemiological patterns are different from those expected for the animal population and the pathogen in question. Existing capacities for the detection and reporting of epidemic and even endemic diseases should be an international priority for the prevention of catastrophic losses in animal and potentially in human life. The veterinary community needs to be more aware of the legal requirements related to forensic investigations so that veterinarians will be prepared to handle evidence properly within their own fields.

Animal Diseases↗

PubMed2005

MHC class I genes in the owl monkey: mosaic organisation, convergence and loci diversity.

The MHC class I molecule plays an important role in immune response, pathogen recognition and response against vaccines and self- versus non-self-recognition. Studying MHC class I characteristics thus became a priority when dealing with Aotus to ensure its use as an animal model for biomedical research. Isolation, cloning and sequencing of exons 1-8 from 27 MHC class I alleles obtained from 13 individuals classified as belonging to three owl monkey species (A. nancymaae, A. nigriceps and A. vociferans) were carried out to establish similarities between Aotus MHC class I genes and those expressed by other New and Old World primates. Six Aotus MHC class I sequence groups (Ao-g1, Ao-g2, Ao-g3, Ao-g4, Ao-g5 and Ao-g6) weakly related to non-classical Catarrhini MHC were identified. An allelic lineage was also identified in one A. nancymaae and two A. vociferans monkeys, exhibiting a high degree of conservation, negative selection along the molecule and premature termination of the open reading frame at exon 5 (Ao-g5). These sequences' high conservation suggests that they more likely correspond to a soluble form of Aotus MHC class I molecules than to a new group of processed pseudogenes. Another group, named Ao-g6, exhibited a strong relationship with Catarrhini's classical MHC-B-C loci. Sequence evolution and variability analysis indicated that Aotus MHC class I molecules experience inter-locus gene conversion phenomena, contributing towards their high variability.

Amino Acid Sequence↗

PubMed2002

Correlates of antiviral immune restoration in acute and chronic HIV type 1 infection: sustained viral suppression and normalization of T cell subsets.

Highly active antiretroviral therapy (HAART) has suppressed viral replication and facilitated normalization of T cell subsets, resulting in restoration of immunity against opportunistic pathogens. Induction of full immune restoration in chronically infected individuals, including HIV-specific helper T cell responses, is considered a priority, particularly if immunological control of HIV is to be achieved. Regimens containing dual protease inhibitors (PIs) have provided greater suppression of viremia than single-PI regimens. We therefore conducted a prospective analysis of factors associated with immune restoration after 3 years of therapy in two cohorts of acutely and chronically HIV-infected patients, comparing dual- versus single-PI regimens. Earlier and more durable returns of p24-specific proliferation were demonstrated in patients receiving dual-PI compared with single-PI regimens. Individuals with restored p24 responses had larger reductions in total HIV-specific cytotoxic T lymphocytes (CTLs) associated with stronger viral suppression, but Gag-specific CTLs remained higher, demonstrating that Gag-specific helper T cell responses were a critical component of functional immune restoration. On examination of clinical factors associated with immune restoration, we demonstrated that decreasing activation of CD8+ T cells (%CD8+ CD38+) and increasing proportions of CD4+ T cells were independently associated with restoration of p24 responses. Minimal immune activation, resulting from maximal suppression of viral replication, was required for long-term restoration and maintenance of Gag-specific T cell responses. This study uniquely demonstrates that dual-PI regimens are superior in achieving these levels of virological control and immune restoration in both chronic and acute infection, compared with single-PI or non-PI regimens.

Acute Disease↗

PubMed2005

Infection and early atherosclerosis: does the evidence support causation?

UNLABELLED: Although clinical manifestations of atherosclerotic coronary heart disease occur in adult life, the initial stages of its development commence in childhood. Therefore, elucidating the pathogenesis of early atherosclerosis and identifying the network of risk factors have become fundamental priorities for both cardiovascular healthcare providers and scientists. There is mounting evidence from both human studies and animal experiments that infectious pathogens could be implicated in atherosclerosis development. The vulnerability of the arterial wall to the adverse effects of infection is probably augmented when additional risk factors and/or certain proatherogenic genetic profiles are also present. The precise mechanisms whereby infection, alone or in synergy with conventional cardiovascular risk factors, could contribute to atherosclerosis are not fully understood. CONCLUSION: Injury to the vascular endothelium, which could be elicited by infection through inflammatory, metabolic, autoimmune, and pathogen-related mechanisms, might be a central link between infection and early atherosclerosis.

Arteries↗