RESUMO
This study examined the frequency of occurrence of non-tuberculous mycobacteria (NTM) in potable water samples from a main trauma hospital in Mexico City. Sixty-nine potable water samples were collected, 23 from each source: cistern, kitchen tap and bathroom showers. Of the 69 samples, 36 harboured NTM species. Twenty-nine of the 36 isolates were Mycobacterium mucogenicum, two Mycobacterium rhodesiae, one Mycobacterium peregrinum, one Mycobacterium fortuitum and three were Mycobacterium spp. Hospital potable water harbouring NTM represents a potential source for nosocomial infections, therefore we suggest that hospital potable water microbiological guidelines should include testing for NTM species.
Assuntos
Água Potável/microbiologia , Mycobacterium/classificação , Mycobacterium/isolamento & purificação , Hospitais , Humanos , México , Infecções por Mycobacterium não Tuberculosas/prevenção & controleRESUMO
This study investigated the possible in vivo transfer of plasmid pRAS1 between Aeromonas salmonicida and A. hydrophila inhabiting two different organs of Cyprinus carpio L. To distinguish transconjugants from naturally occurring antibiotic resistant bacteria, twelve luminescent transposon-tagged A. hydrophila strains using mini Tn5luxCDABEKm2 transposon were generated. In conjugal transfer experiments, fish were conditioned with the donor bacteria and subsequently immersed in water containing the recipient strain. Bacteria were recovered from gills and intestines and isolated by growth on selective plates. Transconjugants were identified by their resistance to the pRAS1 encoded antimicrobials and by light emission. In vivo transfer frequencies ranged between 10(-3) and 10(-6) and were somewhat lower in intestines, compared to gills. Transfer frequencies were also smaller relative to those obtained in vitro. The minimal amount of donor and recipient bacteria needed to yield detectable transconjugants in vivo was 1 x 10(4) CFU mL(-1). Implications of this plasmid transfer in natural settings and its possible consequences to human health are discussed.
Assuntos
Aeromonas hydrophila/genética , Aeromonas salmonicida/genética , Carpas/microbiologia , Doenças dos Peixes/microbiologia , Transferência Genética Horizontal , Infecções por Bactérias Gram-Negativas/veterinária , Plasmídeos/genética , Animais , Elementos de DNA Transponíveis , Infecções por Bactérias Gram-Negativas/microbiologia , Humanos , MutagêneseRESUMO
A total of 82 strains of presumptive Aeromonas spp. were identified biochemically and genetically (16S rDNA-RFLP). The strains were isolated from 250 samples of frozen fish (Tilapia, Oreochromis niloticus niloticus) purchased in local markets in Mexico City. In the present study, we detected the presence of several genes encoding for putative virulence factors and phenotypic activities that may play an important role in bacterial infection. In addition, we studied the antimicrobial patterns of those strains. Molecular identification demonstrated that the prevalent species in frozen fish were Aeromonas salmonicida (67.5%) and Aeromonas bestiarum (20.9%), accounting for 88.3% of the isolates, while the other strains belonged to the species Aeromonas veronii (5.2%), Aeromonas encheleia (3.9%) and Aeromonas hydrophila (2.6%). Detection by polymerase chain reaction (PCR) of genes encoding putative virulence factors common in Aeromonas, such as aerolysin/hemolysin, lipases including the glycerophospholipid-cholesterol acyltransferase (GCAT), serine protease and DNases, revealed that they were all common in these strains. Our results showed that first generation quinolones and second and third generation cephalosporins were the drugs with the best antimicrobial effect against Aeromonas spp. In Mexico, there have been few studies on Aeromonas and its putative virulence factors. The present work therefore highlights an important incidence of Aeromonas spp., with virulence potential and antimicrobial resistance, isolated from frozen fish intended for human consumption in Mexico City.
Assuntos
Aeromonas/classificação , Antibacterianos/farmacologia , Alimentos Congelados/microbiologia , Alimentos Marinhos/microbiologia , Tilápia/microbiologia , Aeromonas/efeitos dos fármacos , Aeromonas/enzimologia , Aeromonas/genética , Animais , Qualidade de Produtos para o Consumidor , DNA Ribossômico/análise , Farmacorresistência Bacteriana , Microbiologia de Alimentos , Humanos , México , Testes de Sensibilidade Microbiana , Fenótipo , Polimorfismo de Fragmento de Restrição , RNA Ribossômico 16S/genética , Virulência/genéticaRESUMO
OBJECTIVE: To identify exposure factors contributing to lead poisoning in school children from Mexico City. MATERIAL AND METHODS: Cross-sectional study of 340 children. A convenience sample of schools and a random sample of children were selected. A questionnaire was filled out and venous blood samples were taken. Lead levels were measured by atomic absorption spectrophotometry. Statistical analysis consisted of comparison of means using Student's t test and ANOVA. Multiple linear regression was used for multivariate analysis. Logarithmic transformation of lead blood levels were used to account for their non-normal distribution. RESULTS: Geometric means for private and public schools were: GM = 8.76 micrograms/dl, 95% CI = 9.1-10.5; GM = 11.5 micrograms/dl, 95% CI = 9.4-13.5. Lead levels were higher among children from public schools who are male, between 6 and 8 years of age, in first and second grade, whose mothers have a profession, who use glazed earthenware utensils, and who live near glazed earthenware shops or factories. CONCLUSIONS: Exposure predictors of lead blood levels are: being between 6 and 8 years of age, having a professional mother, using glazed earthenware utensils, living near glazed earthenware shops or factories, and studying the second grade of elementary school.
Assuntos
Exposição Ambiental , Chumbo/sangue , Criança , Estudos Transversais , Feminino , Humanos , Masculino , México , Análise de Regressão , Instituições Acadêmicas , Inquéritos e QuestionáriosRESUMO
OBJECTIVE: To evaluate the differences between indoor and outdoor ozone (O3) and nitrogen dioxide (NO2) levels at a school located in southwest Mexico City. MATERIAL AND METHODS: Indoor and outdoor O3 and NO2 levels were measured daily between January and April 1990 by manual monitoring. RESULTS: Indoor and outdoor concentrations of nitrogen dioxide did not surpass the Mexican standard (0.21 ppm). The correlation coefficient between maximum NO2 concentrations measured by the city's local monitoring station and those measured outside the classroom was 0.82 (p < 0.001). Regarding ozone, its maximum outdoor concentration was 0.29 ppm and indoor concentrations were on average below 0.06 ppm (maximum = 0.17 ppm). The indoor/outdoor correlation coefficient was 0.72, and for every 1.7 ppm outside, there was 1.0 ppm inside (p < 0.05). CONCLUSIONS: Since the highest outdoors O3 concentrations were observed between 11:00 and 14:00 hrs, it is recommendable to have recess before this time.
Assuntos
Poluentes Atmosféricos/análise , Poluição do Ar em Ambientes Fechados/análise , Escolas Maternais/normas , México , Óxido Nítrico/análise , Ozônio/análiseRESUMO
Uremic polyneuropathy (UPNP) is a serious complication of chronic renal failure (CRF) in adults; however, its prevalence is unknown in the pediatric population. An easy-to-perform maneuver for its detection in children is the evaluation of "H" reflex. The objective of this study was to validate the usefulness of the "H" reflex maneuver for the diagnosis of UPNP in pediatric dialysis patients for CRF. Thirty-seven CRF patients were paired with healthy controls by age and sex. The patients were being treated with dialysis or one of its variants. Information was obtained regarding diagnosis, duration, and control of dialysis. Neurological examination was performed, conduction velocities in sensory and motor nerves were measured, and "H" reflex elicited bilaterally. Peripheral polyneuropathy was determined by the presence of at least two nerves with alterations in latency and/or conduction velocities. It was found that 59.4% (22/37) of the children with CRF treated with dialysis developed UPNP, 17 with ambulatory peritoneal dialysis, and 5 with hemodialysis. There was no difference in diagnosis, duration of dialysis, or control of the same in these patients from other CRF patients who did not have UPNP. All patients were clinically asymptomatic. "H" reflex showed a sensibility of 44%, a specificity of 87%, a predictive value positive of 66%, and a predictive value negative of 76%, when measured to 28 msec. With a 30 msec duration specificity rises to 95%. UPNP presents asymptomatically in pediatric patients. "H" reflex is an adequate screening test for the selection of pediatric patients to be tested further.
Assuntos
Reflexo H , Falência Renal Crônica/complicações , Doenças do Sistema Nervoso Periférico/diagnóstico , Doenças do Sistema Nervoso Periférico/etiologia , Adolescente , Criança , Feminino , Humanos , Falência Renal Crônica/terapia , Masculino , Condução Nervosa , Diálise Peritoneal , Estudos Prospectivos , Tempo de Reação , Diálise Renal , Sensibilidade e EspecificidadeRESUMO
OBJECTIVE: To evaluate the relation between calcium intake and blood lead levels in women of reproductive age living in Mexico City. MATERIAL AND METHODS: Blood lead was assayed in 198 women of 15-48 years of age. By interrogation, the calcium intake was calculated from the frequency of consumption of 11 foods which provide nearly 95% of the intake of calcium in Mexico. RESULTS: The mean blood lead was 9.71 micrograms/dL (range 1 to 39). We observed a statistically significant decreasing trend between the risk of having blood lead levels exceeding 10 mu/dL and the increase in calcium intake. CONCLUSION: Our study suggests the need to evaluate interventions such as modifications in the consumption of milk, cheese, and other calcium rich foods, and their effect on blood lead levels.
Assuntos
Cálcio da Dieta/administração & dosagem , Chumbo/sangue , Adolescente , Adulto , Feminino , Humanos , Pessoa de Meia-Idade , Análise de RegressãoRESUMO
This paper reports on the prevalence of lead poisoning in children between 1 and 5 years of age living in a marginal area to the north of Mexico City and also includes an evaluation of sources of exposure to this metal in the same area. The results show that 67.5% of the children studied have blood lead (PbB) levels > or = 10 micrograms/100 ml. Twenty-one percent of these children (1987) had PbB levels that required medical evaluation (> or = 20 micrograms/100 ml- < or = 40 micrograms/100 ml), and 112 children needed medical treatment (PbB > or = 40 micrograms/100 ml). In addition, the study found that the probability of higher blood lead levels (> or = 20 micrograms/dl) corresponds to children whose mothers use lead-glazed pottery dishes (OR = 2.80; CI 95%, 1.55-5.07) and to children who habitually bite colored pencils (OR = 2.05; CI 95%, 1.13-3.71) compared, respectively, with children whose mothers do not use that type of dishes and children who do not bite pencils. Our results provide baseline information for estimating the impact and costs of population-based interventions aimed at these populations and also confirm the need to strengthen health education programs to promote the reduction of lead exposure in the general population.
Assuntos
Poluentes Ambientais/sangue , Intoxicação por Chumbo/epidemiologia , Chumbo/sangue , Pré-Escolar , Feminino , Humanos , Lactente , Intoxicação por Chumbo/sangue , Intoxicação por Chumbo/etiologia , Masculino , México/epidemiologia , Prevalência , Classe SocialRESUMO
The aim of this study was to evaluate the validity and reproducibility between ozone measurements obtained with passive ozone monitors and those registered with a continuous ozone monitor, to determine the applicability of passive monitors in epidemiological research. The study was carried out during November and December 1992. Indoor and outdoor classroom air ozone concentrations were analyzed using 28 passive monitors and using a continuous monitor. The correlation between both measurements was highly significant (r = 0.089, p < 0.001), indicating a very good validity. Also, the correlation between the measurements obtained with two different passive monitors exposed concurrently was very high (r = 0.97, p < 0.001), indicating a good reproducibility in the measurements of the passive monitors. The relative error between the concentrations measured by the passive monitors and those from the continuous monitor tended to decrease with increasing ozone concentrations. The results suggest that passive monitors should be used to determine cumulative exposure of ozone exceeding 100 ppb, corresponding to an exposure period greater than five days, if used to analyze indoor air.
Assuntos
Monitoramento Ambiental/instrumentação , Ozônio/análise , Poluição do Ar em Ambientes Fechados/análise , Monitoramento Ambiental/métodos , México , Reprodutibilidade dos Testes , Estações do Ano , Fatores de TempoRESUMO
Fifty-one cooked ham samples were analized by three methods for investigation of Staphylococcus aureus; Modified Van Doorne and American Public Health Association; The Official Mexican Method. The first two are enrichment methods and in all three a comparison between Baird Parker agar and salt milk agar was done. The modified Van Doorne technique was the best for isolation of S. aureus from cooked ham. In Baird Parker agar it was possible to demonstrate the presence of S. aureus in all positive samples. The study shows the importance of using Baird Parker broth as an enrichment medium for the isolation of S. aureus from products in which a thermal treatment and addition of salts as sodium chloride and nitrites, inhibit the growth of this microorganism.
Assuntos
Carne/microbiologia , Staphylococcus aureus/isolamento & purificação , Animais , Técnicas Bacteriológicas , Meios de Cultura , Conservação de Alimentos , SuínosRESUMO
There are many media recommended for the isolation of Staphylococcus aureus from foods, but only with some media one can obtain a good growth started with stressed cells. The Baird Parker (BP) medium is considered the best choice to recover stressed cells, however, it is not as good a medium to isolate Staphylococcus aureus from powder milk. Therefore, it is important to count with alternative media to enhance the chance for Staphylococcus aureus to grow from dehydrated products. Thirty-one powder milk samples contaminated with Staphylococcus aureus were analysed by Baird Parker method, employing four culture media: Baird Parker (BP), Baird Parker + tween + MgCl2 (BPTM), Pork plasma with bovine fibrinogen agar (PPF) and Salt Milk agar (SL). Staphylococcus aureus was isolated in SL, 38.7%; in BP, 3.2%; in BPTM, 6.4%; and PPF, 0%.
Assuntos
Técnicas Bacteriológicas , Laticínios/microbiologia , Microbiologia de Alimentos , Leite/microbiologia , Staphylococcus aureus/isolamento & purificação , Ágar , Animais , Bovinos/sangue , Fibrinogênio , Cloreto de Magnésio , Polissorbatos , Staphylococcus aureus/crescimento & desenvolvimento , Suínos/sangueRESUMO
Demonstration of Staphylococcal Thermonuclease (TNase) from Powder Milk. Some authors have reported that the number of Staphylococcus aureus needed to produce a food-poisoning is 10(6) CFU per gram of food, however, other authors have reported foods without microorganisms but these have produced food-poisoning. Because the methods for staphylococcal enterotoxins demonstration in foods are laborious and expensive procedures, in this paper we tried to demonstrate the thermonuclease (TNase) presence in foods directly, as a helper test for screening foods suspected to be contaminated with this microorganism. To 112 powder milk samples were determined TNase presence by Tatini's et al (1976) and Lachica's (1972) technics, 31 of this samples had S. aureus. Only with Lachica's technique it could be possible to demonstrate TNase in 17 of 112 analyzed samples, 14 of these had viable S. aureus.