RESUMO
Maternal fish consumption exposes the fetus to beneficial nutrients and potentially adverse neurotoxicants. The current study investigated associations between maternal fish consumption and child neurodevelopmental outcomes. Maternal fish consumption was assessed in the Seychelles Child Development Study Nutrition Cohort 1 (n 229) using 4-day food diaries. Neurodevelopment was evaluated at 9 and 30 months, and 5 and 9 years with test batteries assessing twenty-six endpoints and covering multiple neurodevelopmental domains. Analyses used multiple linear regression with adjustment for covariates known to influence child neurodevelopment. This cohort consumed an average of 8 fish meals/week and the total fish intake during pregnancy was 106·8 (sd 61·9) g/d. Among the twenty-six endpoints evaluated in the primary analysis there was one beneficial association. Children whose mothers consumed larger quantities of fish performed marginally better on the Kaufman Brief Intelligence Test (a test of nonverbal intelligence) at age 5 years (ß 0·003, 95 % CI (0, 0·005)). A secondary analysis dividing fish consumption into tertiles found no significant associations when comparing the highest and lowest consumption groups. In this cohort, where fish consumption is substantially higher than current global recommendations, maternal fish consumption during pregnancy was not beneficially or adversely associated with children's neurodevelopmental outcomes.
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Compostos de Metilmercúrio , Efeitos Tardios da Exposição Pré-Natal , Humanos , Feminino , Animais , Desenvolvimento Infantil , Seicheles , Estado NutricionalRESUMO
We identified Encephalitozoon cuniculi genotype II parasites as a cause of extraintestinal microsporidiosis in 2 owners of birds also infected with E. cuniculi. Patients experienced long-lasting nonspecific symptoms; the disease course was more progressive in a patient with diabetes. Our findings suggest direct bird-to-human transmission of this pathogen.
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Encephalitozoon cuniculi , Encefalitozoonose , Microsporidiose , Animais , Aves , Encephalitozoon cuniculi/genética , Encefalitozoonose/epidemiologia , Encefalitozoonose/parasitologia , Encefalitozoonose/veterinária , Genótipo , Humanos , Microsporidiose/diagnóstico , Microsporidiose/epidemiologiaRESUMO
Food, particularly milk and cheese, may be a reservoir of multi-drug resistant Staphylococcus aureus strains, which can be considered an important issue in terms of food safety. Furthermore, foods of animal origin can be a cause of staphylococcal food poisoning via the production of heat-stable enterotoxins (SE). For this reason, we investigated the prevalence of and characterized Staphylococcus aureus strains isolated from milk and fresh soft cheese obtained from farms located in Wielkopolskie and Zachodniopomorskie Provinces in Poland. Overall, 92% of S. aureus isolates were positive for at least one of the 18 enterotoxin genes identified, and 26% of the strains harbored 5 to 8 enterotoxin genes. Moreover, the S. aureus strains contained genes conferring resistance to antibiotics that are critically important in both human and veterinary medicine, i.e., ß-lactams (mecA), aminoglycosides (aac(6')/aph(2â³), aph(3')-IIIa, ant(4')-Ia) and MLSB (erm(A), msr(A), lun(A)). The antimicrobial susceptibility of S. aureus to 16 antibiotics representing 11 different categories showed that 74% of the strains were resistant to at least 1 antibiotic. Moreover, 28% of the strains showed multidrug resistance; in particular, two methicillin-resistant S. aureus strains (MRSA) exhibited significant antibiotic resistance. In summary, our results show that dairy products are contaminated by S. aureus strains carrying genes encoding a variety of enterotoxins as well genes conferring resistance to antibiotics. Both MRSA strains and MSSA isolates showing multidrug resistance were present in foods of animal origin.
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Staphylococcus aureus Resistente à Meticilina , Infecções Estafilocócicas , Animais , Antibacterianos/farmacologia , Enterotoxinas/genética , Humanos , Staphylococcus aureus Resistente à Meticilina/genética , Testes de Sensibilidade Microbiana , Leite , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/genéticaRESUMO
Pneumocystis jirovecii is an opportunistic fungus occurring in human lungs. The group at highest risk consists of HIV-infected and non-HIV-infected immunosuppressed individuals. In these patients, P. jirovecii infection may lead to Pneumocystis pneumonia; it may, however, persist also in an asymptomatic form. This study aimed to determine the prevalence of P. jirovecii and potential risk factors for infection in a group of renal transplant recipients and to characterize the genetic diversity of this fungus in the studied population. Sputum specimens from 72 patients were tested for presence of P. jirovecii using immunofluorescence microscopy, as well as nested PCR targeting the mtLSU rRNA gene. Genotyping involving analysis of four loci-mtLSU rRNA, CYB, DHPS, and SOD-was used to characterize the diversity of the detected organisms. Pneumocystis DNA was detected in eight (11.11%) patients. It has been shown that low eosinophil count and dual immunosuppressive treatment combining prednisone and calcineurin inhibitors are potential risk factors for colonization. Analysis of genotype distribution showed an association of the wild-type genotype of mtLSU rRNA with lower average age of patients and shorter time after kidney transplantation. Furthermore, CYB 2 genotype was detected only in patients with the ongoing prophylaxis regimen. In conclusion, renal transplant recipients are at risk of Pneumocystis colonization even a long time after transplantation. The present preliminary study identifies specific polymorphisms that appear to be correlated with certain patient characteristics and highlights the need for deeper investigation of these associations in renal transplant recipients.
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Transplante de Rim/efeitos adversos , Pneumocystis carinii/isolamento & purificação , Pneumonia por Pneumocystis/microbiologia , Complicações Pós-Operatórias/microbiologia , Adulto , Idoso , Feminino , Variação Genética , Genótipo , Humanos , Hospedeiro Imunocomprometido , Pulmão/microbiologia , Masculino , Pessoa de Meia-Idade , Pneumocystis carinii/classificação , Pneumocystis carinii/genética , Pneumonia por Pneumocystis/etiologia , Pneumonia por Pneumocystis/imunologia , Reação em Cadeia da Polimerase , Complicações Pós-Operatórias/imunologia , Prevalência , Transplantados/estatística & dados numéricos , Adulto JovemRESUMO
Background: Among patients with hip joint endoprosthesis, periprosthetic osteolysis is the most common complication following primary arthroplasty, and subsequent implant loosening is the leading cause of arthroplasty revision. Causes of stability loss, though not always evident, can be mechanical, allergic, or infectious (bacterial and fungal agents) in nature. Microsporidia, widespread opportunistic fungal pathogens that infect most human tissues, are a potential infectious cause of stability loss. Infections caused by Encephalitozoon species-one of the most common microsporidial pathogens in humans-primarily localize to intestinal and respiratory tracts, but can disseminate to tissues throughout the body. Methods: We examined 53 immunocompetent patients, 23 after revision and 30 after primary hip arthroplasty, for infection by Encephalitozoon species. Periprosthetic tissue, urine sediments, and stool samples were tested by microscopic examination and genus-specific nested polymerase chain reaction followed by genotyping. Results: Ten patients had Encephalitozoon-positive periprosthetic tissues, 9 (39%) after revision and 1 (3.3%) after primary hip arthroplasty. Among the tissue-positive postrevision patients, 7 had a positive urine sample and 1 had a positive stool sample. Encephalitozoon cuniculi genotype II was identified in 88.8% (16/18) of samples. Two urine samples were positive for a novel Encephalitozoon species. Conclusions: Encephalitozoon cuniculi should be considered as a cause of osteolysis in hip periprosthetic tissue, leading to a loss of implant stability.
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Artroplastia de Quadril , Encefalitozoonose/complicações , Osteólise/microbiologia , Infecções Relacionadas à Prótese/microbiologia , Idoso , Idoso de 80 Anos ou mais , Encephalitozoon cuniculi/genética , Encephalitozoon cuniculi/isolamento & purificação , Fezes/microbiologia , Feminino , Articulação do Quadril/microbiologia , Articulação do Quadril/cirurgia , Humanos , Imunocompetência , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Infecções Relacionadas à Prótese/urinaRESUMO
Pneumocystis jirovecii is an opportunistic fungus causing Pneumocystis pneumonia primarily in immunosuppressed patients. However, immunocompetent individuals may become colonized and, as asymptomatic carriers, serve as reservoirs of the pathogen. Moreover, these asymptomatic carriers are at higher risk of developing pneumonia if favorable conditions occur. This study aimed to determine the prevalence of P. jirovecii in patients with various pulmonary diseases and to characterize the genetic diversity of organisms circulating in the studied population. Bronchial washing specimens from 105 patients were tested for presence of P. jirovecii using nested polymerase chain reaction (PCR) targeting the mtLSU rRNA gene, as well as immunofluorescence microscopy. Multilocus sequence typing involving analysis of three loci-mtLSU rRNA, CYB, and SOD-was used for genotyping analysis. P. jirovecii DNA was detected in 17 (16.2%) patients. Amplification of the SOD locus was successful only in five cases (29.4% of the positive patients), while mtLSU rRNA and CYB were genotyped in all positive samples. Therefore, combined genotypes were identified based only on mtLSU rRNA and CYB loci. Eight different genotypes were identified, with Pj 1 and Pj 2 being the most prevalent (29.4% of patients each). There was no statistical correlation between these genotypes and demographic or clinical data; however, we found that infection with mutant CYB strains occurred only in patients diagnosed with lung cancer. Of the potential predictors examined, only immunosuppressive treatment was significantly associated with colonization. In conclusion, patients with various respiratory diseases, especially when immunosuppressed, are at risk of Pneumocystis colonization.
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Portador Sadio/microbiologia , Genótipo , Pneumopatias/microbiologia , Tipagem de Sequências Multilocus/métodos , Técnicas de Tipagem Micológica/métodos , Infecções por Pneumocystis/microbiologia , Pneumocystis carinii/classificação , Adulto , Idoso , Idoso de 80 Anos ou mais , Líquido da Lavagem Broncoalveolar/microbiologia , DNA Fúngico/genética , DNA Ribossômico/genética , Feminino , Proteínas Fúngicas/genética , Variação Genética , Humanos , Pneumopatias/complicações , Masculino , Pessoa de Meia-Idade , Pneumocystis carinii/genética , Pneumocystis carinii/isolamento & purificação , Reação em Cadeia da Polimerase , RNA Ribossômico 28S/genéticaRESUMO
Microsporidia are opportunistic pathogens in nature infecting all animal phyla. There is a potential risk of microsporidian spores transmission from urban rooks inhabiting some metropolitan cities to people through casual interactions. The aim of this study was to identify microsporidia species in the droppings of rooks in Wroclaw, Poland. A total of 15 collective sets of droppings were examined using nested-PCR method. Amplification of ITS rRNA gene revealed the presence of Enterocytozoon bieneusi D, Peru 6, and Encephalitozoon hellem 1A genotypes. This study indicates that excreta of urban rooks can be an important source of human infection with these pathogens.
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Corvos/microbiologia , DNA Ribossômico/genética , Microsporídios/classificação , Animais , DNA Fúngico/genética , Fezes/microbiologia , Genótipo , Microsporídios/genética , Filogenia , Polônia , Reação em Cadeia da PolimeraseRESUMO
INTRODUCTION AND OBJECTIVES: Blastocystis hominis s. l. is one of the most commonly detected protozoa in the human large intestine. The aim of the study was to determine the genetic subtypes of Blastocystis hominis s. l. occurring in humans in Poland. MATERIALS AND METHODS: Stool samples from patients diagnosed in the Laboratory of the Department of Parasitology, National Institute of Public Health National Institute of Hygiene (NIZP-PZH) and in the Parasitology Laboratory of the Hospital for Infectious Diseases in Warsaw were examined. Blastocystis subtypes were assayed based on the fragment of small-subunit ribosomal RNA gene sequences (SSU rDNA). RESULTS: The examined isolates were classified into five Blastocystis subtypes (STs), fifteen of which belonged to ST3, three to ST1, two to ST2, two to ST6, and one isolate belonged to ST7. In three cases the subtype of isolate was not identified. DISCUSSION AND CONCLUSIONS: In Poland, the subtypes ST1, ST2, ST3, ST4, ST6 and ST7 have been reported in humans so far. The ST6 and ST7 subtypes are rarely detected in humans in Europe. In Poland, the ST6 subtype was previously described in chickens. On the basis of the studies, it was found that Blastocystis isolated from humans in Warsaw show high genetic diversity. In order to determine the possible pathogenic potential of individual Blastocystis subtypes, special epidemiological studies are required.
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Infecções por Blastocystis/parasitologia , Blastocystis hominis/parasitologia , Diarreia/parasitologia , Fezes/parasitologia , Adulto , Animais , Infecções por Blastocystis/classificação , Infecções por Blastocystis/epidemiologia , Blastocystis hominis/classificação , DNA de Protozoário/genética , Diarreia/classificação , Diarreia/epidemiologia , Variação Genética , Humanos , Masculino , PolôniaRESUMO
BACKGROUND: Ischaemia of the lower limbs is frequently followed by inflammation and, in advanced cases, necrosis of peripheral tissues. Whether this is caused by arterial hypoperfusion only or by the presence of bacteria in the arterial walI as well remains unclear. The aim of the study was to prove the presence and source of bacteria in arterial specimens and evaluate their chemotactic properties resulting in the formation of periarterial cellular infiltrates. MATERIALS AND METHODS: Bacterial culture and testing for 16sRNA were performed in fragments of popliteal artery harvested from amputated limbs. Carotid artery plaques served as controls. Fragments of arteries were transplanted into scid mice to evaluate their chemotactic activity for macrophages. RESULTS: a) higher prevalence of isolates and 16sRNA in atherosclerotic popliteal than carotid arteries, b) high density of plaque and periarterial infiltrates and mRNA level for pro-inflammatory cytokines in popliteal arteries, c) prevalent microbes were Staphylococcus aureus, S. epidermidis and Enterococci, d) foot skin and arterial bacterial phenotypes and DNA revealed evident similarities, and e) more intensive mouse macrophage accumulation in popliteal than carotid implants into scid mice. CONCLUSIONS: The presence of bacteria in the lower limb arterial wall was documented. They may predispose to inflammation secondary to ischaemic changes.
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Aterosclerose/microbiologia , Bactérias/genética , DNA Bacteriano/genética , Inflamação/microbiologia , Extremidade Inferior/irrigação sanguínea , Placa Aterosclerótica , Artéria Poplítea/microbiologia , RNA Ribossômico 16S/genética , Idoso , Amputação Cirúrgica , Animais , Aterosclerose/diagnóstico , Aterosclerose/metabolismo , Aterosclerose/cirurgia , Bactérias/classificação , Artérias Carótidas/microbiologia , Artérias Carótidas/transplante , Citocinas/metabolismo , Feminino , Xenoenxertos , Humanos , Inflamação/diagnóstico , Inflamação/metabolismo , Mediadores da Inflamação/metabolismo , Macrófagos/metabolismo , Macrófagos/microbiologia , Masculino , Camundongos SCID , Pessoa de Meia-Idade , Artéria Poplítea/metabolismo , Artéria Poplítea/patologia , Artéria Poplítea/transplante , RibotipagemRESUMO
Pneumocystis pneumonia is an opportunistic disease caused by invasion of unicellular fungus Pneumocystis jirovecii. Initially, it was responsible for majority of morbidity and mortality cases among HIV-infected patients, which later have been reduced due to the introduction of anti-retroviral therapy, as well as anti-Pneumocystis prophylaxis among these patients. Pneumocystis pneumonia, however, is still a significant cause of mortality among HIV-negative patients being under immunosuppression caused by different factors, such as transplant recipients as well as oncologically treated ones. The issue of pneumocystosis among these people is particularly emphasized in the article, since rapid onset and fast progression of severe symptoms result in high mortality rate among these patients, who thereby represent the group of highest risk of developing Pneumocystis pneumonia. In contrast, fungal invasion in immunocompetent people usually leads to asymptomatic colonization, which frequent incidence among healthy infants has even suggested the possibility of its association with sudden unexpected infant death syndrome. In the face of emerging strains with different epidemiological profiles resulting from genetic diversity, including drug-resistant genotypes, the colonization phenomenon desires particular attention, discussed in this article. We also summarize specific and sensitive methods, required for detection of Pneumocystis invasion and for distinguish colonization from the disease.
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Infecções Oportunistas Relacionadas com a AIDS/microbiologia , Hospedeiro Imunocomprometido , Pneumocystis carinii/genética , Pneumonia por Pneumocystis/complicações , Pneumonia por Pneumocystis/microbiologia , Genótipo , Humanos , Pneumocystis carinii/fisiologiaRESUMO
The Cryptosporidium hedgehog genotype, which has been reported previously in hedgehogs and horses, was identified as the cause of the diarrheal disease cryptosporidiosis in an immunocompetent man in the Czech Republic. This is the first report of human illness caused by the Cryptosporidium hedgehog genotype.
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Criptosporidiose/diagnóstico , Criptosporidiose/parasitologia , Cryptosporidium/classificação , Cryptosporidium/isolamento & purificação , Gastroenterite/diagnóstico , Gastroenterite/parasitologia , Adulto , Análise por Conglomerados , Cryptosporidium/genética , República Tcheca , DNA de Protozoário/química , DNA de Protozoário/genética , DNA Ribossômico/química , DNA Ribossômico/genética , Genes de RNAr , Genótipo , Humanos , Masculino , Dados de Sequência Molecular , Filogenia , Proteínas de Protozoários/genética , RNA de Protozoário/genética , RNA Ribossômico 18S/genética , Análise de Sequência de DNARESUMO
A urinary tract coinfection, caused by Encephalitozoon cuniculi genotype II and Enterocytozoon bieneusi genotype D, was identified in an HIV-seronegative renal transplant recipient kept under lifelong immunosuppression. To our knowledge, this is the first report describing concurrent infection with these two microsporidia species in organ transplant recipients.
Assuntos
Coinfecção/diagnóstico , Coinfecção/microbiologia , Encephalitozoon cuniculi/isolamento & purificação , Enterocytozoon/isolamento & purificação , Infecções Urinárias/diagnóstico , Infecções Urinárias/microbiologia , Sistema Urinário/microbiologia , Adulto , Encefalitozoonose/diagnóstico , Encefalitozoonose/microbiologia , Humanos , Transplante de Rim/métodos , Masculino , Microsporidiose/diagnóstico , Microsporidiose/microbiologia , TransplantadosRESUMO
Some health agencies have issued precautionary principle fish advisories to pregnant women based on the presence of methylmercury (MeHg) in fish that could possibly be harmful to the developing fetus. Fish, however, is a rich source of selenium (Se) and other nutrients essential for normal brain development. Selenium is also thought to have a key role in alleviating MeHg toxicity. We estimated the dietary Se and MeHg intakes and dietary Se:Hg molar ratios from the fish consumed in a high fish-eating pregnant cohort where no adverse associations of fish consumption and outcomes has been reported. We used dietary data collected as part of the Seychelles Child Development Study Nutrition Cohort 2 (n = 1419). In this cohort 98% of participants consumed fish, with an average intake of 106.2 g per day. Daily Se intakes from fish consumption were 61.6 µg/ d, within the range recommended during pregnancy. The mean dietary Se:Hg molar ratios was 6. These findings demonstrate that fish consumption exposes pregnant Seychellois women to Se in excess of MeHg. Based on these findings, fish consumption, especially fish with Se:Hg ratios above 1, may help pregnant women achieve optimum dietary Se intakes, which may protect against MeHg toxicity.
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Mercúrio , Compostos de Metilmercúrio , Selênio , Criança , Animais , Feminino , Humanos , Gravidez , Mercúrio/análise , Selênio/análise , Seicheles , Desenvolvimento Infantil , PeixesRESUMO
Staphylococci colonize the skin and mucous membranes of different animals. The purpose of this study was to determine the staphylococcal composition of the skin microbiota of healthy, non-vet visiting, and antimicrobially non-treated sheep and goats. In total, 83 strains (44 from goats and 39 from sheep) were isolated and identified using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The diversity of the isolated Staphylococcus species was relatively high, and only coagulase-negative staphylococci (CoNS) were isolated. In sheep, S. vitulinus (9/39, 23.1%) was the most common species, followed by S. equorum (8/39, 20.5%), S. lentus (7/39, 17.9%), S. sciuri (6/39, 15.4%), S. xylosus (6/39, 15.4%), S. warneri (1/39, 2.6%), S. simulans (1/39, 2.6%), and S. nepalensis (1/39, 2.6%). In the goats, the most common species was S. sciuri, which was detected in 13 (29.5%) animals. The goat skin was also inhabited by S. equorum (7/44, 15.9%), S. vitulinus (6/44, 13.6%), S. cohnii (5/44, 11.4%), S. lentus (4/44, 9.1%), S. suscinus (3/44, 6.8%), S. caprae, (2/44, 4.5%), S. auricularis (2/44, 4.5%), S. warneri (1/44, 2.3%), and S. xylosus (1/44, 2.3%). Only one S. xylosus strain of goat origin carried the enterotoxin gene (sea). Antimicrobial resistance was not common among the isolated staphylococci. Only 31 (37.3%) strains were resistant to at least one antimicrobial agent, with the highest frequency of resistance to penicillin (16.8%), followed by clindamycin (9.6%), erythromycin (8.4%), moxifloxacin (8.4%), and tetracycline (7.2%). All isolates were susceptible to eight antibiotics (amikacin, gentamycin, ciprofloxacin, levofloxacin, rifampicin, chloramphenicol, trimethoprim-sulfamethoxazole, and tigecycline), representing six different classes. Three isolates displayed a multi-resistance phenotype (MDR): the goat isolates S. cohnii and S. sciuri, as well as the ewe isolate S. xylosus. The MDR S. cohnii isolate was found to be methicillin-resistant and carried the mecA gene. Moreover, the staphylococci isolated from the healthy animals carried genes conferring resistance to ß-lactams (mecA, blaZ), tetracyclines (tetL, tetK), macrolides (ermB, ermC), lincosamides (lnu), and fluoroquinolones (grlA). However, the prevalence of these genes was low.
RESUMO
Staphylococci are a natural component of the skin microbiota of many organisms, including humans and birds. As opportunistic pathogens, they can cause a variety of infections in humans. The close contact between domestic pigeons and their owners provide an opportunity for exchange of skin-associated bacteria. In this study, 41 healthy racing pigeons were tested. Staphylococci were detected on the skin of each bird (41/41, 100%). Isolates were identified at the species level using matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS). The diversity of the Staphylococcus species was relatively high and coagulase-negative staphylococci (CoNS) were predominantly isolated. In total, ten different staphylococcal species were identified. S. lentus (19/41, 46.3%) was noted most frequently. The pigeon skin was also inhabited by S. xylosus (6/41, 14.6%), S. equorum (4/41, 9.8%), S. hyicus (3/41, 7.3%), S. intermedius (2/41, 4.9%), S. sciuri (2/41, 4.9%), S. vitulinus (2/41, 4.9%), S. lugdunensis (1/41, 2.4%), S. hominis (1/41, 2.4%), and S. auricularis (1/41, 2.4%). Our results indicate that domestic pigeons may carry pathogens with zoonotic potential. All strains were susceptible to 12 antibiotics (ciprofloxacin, clindamycin chloramphenicol, erythromycin, fosfomycin, gentamicin, levofloxacin, norfloxacin, rifampicin, tobramycin, trimethoprim/sulfamethoxazole, vancomycin) representing 8 different classes. None isolate displayed a multidrug-resistant phenotype. Resistance to tetracycline (6/41, 14.6%) and to penicillin (4/41, 9.7%) was shown. The mecA gene was not detected in the examined strains and no methicillin-resistant staphylococci were found on the skin of the healthy pigeons.
Assuntos
Columbidae , Microbiota , Humanos , Animais , Staphylococcus/genética , Antibacterianos/farmacologia , PeleRESUMO
Cutaneous larva migrans (CLM) is a dermatosis caused by accidental infestation with animal hookworms and is widely distributed in tropical and subtropical regions. Humans become infected when their skin comes into contact with soil contaminated with dog faeces. The filariform larvae penetrate and burrow into human skin, causing a condition known as "creeping eruption". We describe a case, well-documented by photos, of CLM infection in a family of three who returned from Thailand.
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Selenium (Se) is an essential trace element for normal neurodevelopment. It is incorporated into multiple selenoenzymes which have roles in the brain and neurological function, the synthesis of thyroid hormones, the antioxidant defense system, DNA synthesis, and reproduction. Fish is a source of both Se and neurotoxic methylmercury (MeHg). Selenium is known to ameliorate the effects of MeHg in experimental animals, but studies in children exposed to both Se and MeHg through prenatal fish consumption have been inconclusive. Research on Se's implications for pregnancy and child neurodevelopment is limited. The aims of this review are to summarize the literature on the biological roles of Se during pregnancy and the potential role in mitigating the effects of MeHg exposure from fish consumption on human health. This review has shown that Se concentrations among pregnant women globally appear insufficient, with the majority of pregnant women reporting Se concentrations below 70 µg/L during pregnancy. The role of Se in child development and its interactions with MeHg in children are inconclusive. Further investigation of the interaction between Se and MeHg in relation to child neurodevelopment in high fish-eating populations is required to fully elucidate effects.
Assuntos
Compostos de Metilmercúrio , Selênio , Oligoelementos , Animais , Criança , Humanos , Feminino , Gravidez , Compostos de Metilmercúrio/toxicidade , Antioxidantes , Exposição Materna , PeixesRESUMO
This paper takes into consideration the performance of traditional bricks as part of a building exterior wall finish. Exterior wall materials change their properties when exposed to external environment. This process is extended over time and its intensity is closely related to microstructure, moisture and freeze-thaw cycles. Two methods of freeze-thaw durability tests were used in this study: standard and defined by the authors. The authors' method incorporated the actual conditions of masonry unit function in exterior wall finish, i.e., cyclical effects of precipitation water, changes in temperature and air humidity. The laboratory test study included 50 freeze-thaw cycles. Three characteristic ranges of pore dimensions were indicated in the analysis: below 0.1 µm, between 0.1 and 3.0 µm and above 3 µm. Based on the method of freeze-thaw durability testing, the areas of microstructure changes were determined. The obtained results were related to the absorption of ceramic building materials. The authors' method confirms the usage of traditional ceramic building materials designed for use in protected walls against water penetration in unprotected exterior wall finish. The critical water saturation method of masonry units (standard) based on extreme environmental conditions generates significant changes in porosity distribution that do not reflect real, i.e., moderate, conditions. This method is appropriate for masonry units operating in severe conditions, i.e., F2. The aim of this study is to suggest a methodology for durability tests of traditional ceramic masonry units to cyclic freezing and thawing, which are only exposed to F1 (moderate) conditions during operation. Changes in the microstructure of the ceramic building materials were used as the primary evaluation criterion. In order to determine the effect of cyclic temperature changes, the freeze-thaw durability test was performed according to generally accepted standard procedures and in-house methodology. The purpose of the study is to point out the individual approach for the analysis of the material-environment system. At the same time, it should inspire researchers to innovative methods which use external conditions in a laboratory environment.
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This paper discusses changes in the microstructure and water absorption of thin-coat mineral-based plasters after prolonged exposure to the external environment and infected with biological corrosion. The results of laboratory and field tests for external thermal insulation composite system Styrofoam-based plasters are presented. The test samples were taken after 6 years of exposure to the external environment. The microstructure parameters such as porosity distribution and water absorption of the plasters were evaluated. The pore size ranges that were sensitive to frost corrosion and capillary flow were separated in the porosity distribution. Based on the porosity and absorption changes, it was found that biological corrosion interferes with the microstructure of the thin-coat mineral-based plasters on the expanded polystyrene substrate.
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Basic factors affecting the appearance of algae discoloration on the surface of the system are recognized effects of the external environment (external temperature and humidity, short- and long-term radiation, precipitation, wind and air pollution). Internal factors are often neglected by international technical documents on the evaluation of the effectiveness of resistance to biocorrosion of the External Thermal Insulation Composite System (ETICS). Based on literature data and in situ research, the basic internal factors responsible for the occurrence or intensification of the biocorrosion process were systematized. Internal factors were divided into two groups: (1) plaster properties and (2) solutions for material layouts and building details. The results of research on these factors indicate that they directly or indirectly influence the humidity condition of plaster and biocorrosion development is a consequence of this state. The opposite issue, the influence of biocorrosion on plaster properties, is analyzed only in patrial way.