RESUMO
BACKGROUND: Low vaccination rates and under-detection of pertussis infections in adolescents and young adults have an impact on the transmission of pertussis to infants. In this study, the proportion of adolescents and young adults with IgG antibodies against B. pertussis antigens, representing recent infection or vaccination, was estimated in a population-based probabilistic survey in Mexico. METHODS: Sera and data from 1,581 subjects, including 1,102 adolescents and 479 young adults (10-19 and 20-25 years old, respectively) randomly selected from Mexico's 2012 National Health and Nutrition Survey, were analyzed. IgG antibodies against pertussis toxin (PT) were measured with the CDC/FDA ELISA. A subset of 234 samples was additionally tested with Bp-IgG PT ELISA kit (EUROIMMUN AG, Lubeck, Germany). Threshold values from corresponding test kits were used to identify recent infection or vaccination. RESULTS: Overall anti-PT IgG seroprevalence was 3.9% (95% CI: 2.3-6.3); 3.1% (95% CI: 1.9-5.0) in adolescents, and 4.9% (95% CI: 2.2-11) in young adults. Seroprevalence did not significantly vary by sex, socioeconomic status, region or rural/urban location. Compared to the CDC/FDA ELISA, the EUROIMMUN test showed a 76% sensitivity and 88% specificity. The weighted estimates represent a considerable burden of recent infection in adolescents and young adults; however, most adolescents and adults were seronegative and, therefore, susceptible to pertussis infection. CONCLUSION: Since booster vaccination to B. pertussis after toddlerhood is not recommended in the Mexican national policy, anti-PT IgG seropositivity may be reasonably attributed to recent infection. Assessing pertussis seroprevalence requires careful consideration of the diagnostic test threshold interpretation and epidemiological model used.
Assuntos
Bordetella pertussis , Coqueluche , Adolescente , Humanos , Lactente , México/epidemiologia , Inquéritos Nutricionais , Estudos Soroepidemiológicos , Coqueluche/diagnóstico , Coqueluche/epidemiologia , Adulto JovemRESUMO
Resumen: Objetivo: Analizar los espectros de absorción neta de las películas radiocrómicas EBT2 y EBT3 para describir su influencia en el comportamiento de las curvas de dosis-respuesta. Metodología: Las películas se irradiaron en un acelerador lineal de 6 MV. La obtención de los espectros de absorción neta se realizó con espectrofotómetro UV/VIS. Las curvas de dosis-respuesta se obtuvieron con un escáner, un láser He-Ne y un espectrofotómetro. Resultados: El espectro de absorción de las EBT2 muestra tres bandas de absorción centradas que conservan la posición y aumentan su intensidad en función de la dosis, sin embargo, este comportamiento no se observa en las películas EBT3. La curva dosis-respuesta muestra la máxima sensibilidad utilizando el espectrofotómetro, pero no muestra un comportamiento definido. Implicaciones: Generación de nuevos conocimientos para la creación de nuevos sistemas ópticos capaces de amplificar la sensibilidad de la respuesta de las películas. Originalidad: Mostrar la correlación entre los espectros de absorción neta y su influencia en las curvas dosis-respuesta en tres diferentes sistemas ópticos. Conclusiones: El comportamiento de los espectros de absorción aunado al comportamiento de las curvas dosis-respuesta nos ayuda a descartar el uso de sistemas ópticos que no garanticen un uso clínico confiable.
Abstract: Objective: To analyze the net absorption spectra of EBT2 and EBT3 radiochromic films to describe their influence on the behavior of dose-response curves. Methodology: The films were irradiated in a linear accelerator of 6 MV. The net absorption spectra were obtained with a UV / VIS spectrophotometer. Dose-response curves were obtained with a scanner, a He-Ne laser and a spectrophotometer. Results: The absorption spectrum of the EBT2 shows three focused absorption bands that retain position and increase their intensity as a function of dose, however, this behavior is not observed in EBT3 films. The dose-response curve shows maximum sensitivity using the spectrophotometer, but does not show a defined behavior. Implications: Generation of new knowledge for the creation of new optical systems capable of amplifying the responsiveness of the films. Originality: Show the correlation between net absorption spectra and their influence on dose-response curves in three different optical systems. Conclusions: The behavior of absorption spectra combined with the behavior of the dose-response curves helps to discard the use of optical systems that do not guarantee a reliable clinical use.
RESUMO
An increasing number of studies pointed out the ubiquitous presence of medical residues in surface and ground water as well as in soil compartments. Not only antibiotics can be found in the environment but also their transformation products about which little information is generally available. The development of bacterial resistance to antibiotics is particularly worrying as it can lead to sanitary and health problems. Studies about the dissemination of antibiotics and associated resistances in the Bolivian Altiplano are scarce. We provide baseline information on the occurrence of Sulfamethoxazole (SMX) and Trimethoprim (TMP) antibiotics as well as on the most common human SMX transformation products (TP) and on the occurrence of sulfonamide resistance genes. The studied water and soil compartments presented high levels of antibiotic pollution. This situation was shown to be mainly linked with uncontrolled discharges of treated and untreated wastewaters, resulting on the presence of antibiotics in the Titicaca Lake. SMX TPs were detected in surface waters and on soil sampled next to the wastewater treatment plant (WWTP). SMX resistance genes sulI and sulII were widely detected in the basin hydrological network, even in areas unpolluted with antibiotics. Mechanisms of co-selection of antibiotic- and metal- resistance may be involved in the prevalence of ARG's in pristine areas with no anthropogenic activity and free of antibiotic pollution.
Assuntos
Antibacterianos/análise , Genes Bacterianos , Lagos/química , Poluentes Químicos da Água/análise , Bolívia , Farmacorresistência Bacteriana/genética , Sulfametoxazol/análise , Trimetoprima/análise , Águas ResiduáriasRESUMO
Methicillin-resistant Staphylococcus aureus (MRSA) isolates (n = 216), collected between January 1999 and May 2003 in a tertiary-care university hospital in Guadalajara, Mexico, were characterised by antibiotype, pulsed-field gel electrophoresis (PFGE) of SmaI macrorestriction fragments, and hybridisation of ClaI digests with mecA- and Tn554-specific DNA probes. Representatives of the single clonal type found were analysed by spa typing, multilocus sequence typing and staphylococcal chromosomal cassette mec (SCCmec) typing, and were tested for the presence of 22 virulence determinants and agr type. A single PFGE pattern was identified, with minor variations over time, with spa type 2, sequence type 5, SCCmec type II, agr type 2 and the presence of the enterotoxin genes seg and sei, the gamma-haemolysin variant gene hlg-v and the leukocidin lukE-lukD genes. In addition, the isolates showed antimicrobial resistance to beta-lactams, macrolides, chloramphenicol and imipenem, and susceptibility to gentamicin, rifampicin, trimethoprim-sulphamethoxazole and vancomycin. Following its appearance in 1997, this clone spread within the hospital, and is now present in most of the hospital units and wards.
Assuntos
Hospitais Universitários , Resistência a Meticilina , Infecções Estafilocócicas/epidemiologia , Staphylococcus aureus/classificação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Antibacterianos/farmacologia , Técnicas de Tipagem Bacteriana , Criança , Pré-Escolar , DNA Bacteriano/análise , Eletroforese em Gel de Campo Pulsado , Genótipo , Humanos , Lactente , México/epidemiologia , Testes de Sensibilidade Microbiana , Pessoa de Meia-Idade , Fenótipo , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Staphylococcus aureus/patogenicidade , Virulência/genéticaRESUMO
Between 1997 and 2000 a single multidrug-susceptible methicillin-resistant Staphylococcus aureus clone, M (sequence type 30 [ST30]-staphylococcal cassette chromosome mec [SCCmec] type IV), was present in a pediatric hospital in Mexico City, Mexico. In 2001 the international multidrug-resistant New York-Japan clone (ST5-SCCmec type II) was introduced into the hospital, completely replacing clone M by 2002.
Assuntos
Resistência a Meticilina/genética , Infecções Estafilocócicas/epidemiologia , Infecções Estafilocócicas/prevenção & controle , Staphylococcus aureus/isolamento & purificação , Criança , Eletroforese em Gel de Campo Pulsado , Hospitais Pediátricos , Humanos , México/epidemiologia , Filogenia , Infecções Estafilocócicas/tratamento farmacológico , Staphylococcus aureus/classificação , Staphylococcus aureus/efeitos dos fármacos , Staphylococcus aureus/genética , Virulência/genéticaRESUMO
We have determined the complete coding sequences of six dengue-1 (DEN-1) viruses isolated from Paraguay and Argentina in 2000 from patients with dengue fever. Sequences of strains 259par00, 280par00, 295arg00, 297arg00 and 301arg00 can encode a polyprotein of 3392 amino acids. Strain 293arg00 circulated as a "wild type+deletion mutant" quasispecies, with a subpopulation characterized by a 3-nucleotide deletion in the NS4A region. This variant, which would encode a three amino acid change in the NS4A protein, was found as a minority population in one additional partially-sequenced isolate from the same outbreak. These six South American strains group into two different clades of the "American-African" DEN-1 genotype-one clade is most closely related to strains isolated from Brazil in 1997, the other to a Peruvian strain isolated in 1991 for which only partial sequence information is available. DEN-1 viruses isolated worldwide comprise at least four different genotypes according to previously defined classification criteria.
Assuntos
Vírus da Dengue/genética , Vírus da Dengue/isolamento & purificação , Dengue/virologia , Surtos de Doenças , Sequência de Aminoácidos , Argentina/epidemiologia , Sequência de Bases , Dengue/epidemiologia , Vírus da Dengue/classificação , Genoma Viral , Humanos , Dados de Sequência Molecular , Paraguai/epidemiologia , Filogenia , Análise de Sequência de DNARESUMO
We sequenced the Capsid-pre Membrane (C/prM) and the Envelope-Nonstructural protein 1 (E/NS1) regions of 24 recent isolates of dengue-1 (DEN-1) from South America. This included 12 Argentinean and 11 Paraguayan DEN-1 strains isolated in 2000 plus a Paraguayan strain isolated in 1988. These sequences were compared with published sequences of DEN-1 isolated worldwide to determine the origin of these isolates. Pairwise comparisons of strains from Paraguay and Argentina revealed a nucleotide divergence of 0-5% in the E/NS1 region and 0-3% in the C/prM region. Our results showed that these viruses belong to the same genotype, but can be separated into two clades. Interestingly, both clades circulated simultaneously in the same geographic area during the 2000 outbreaks. Amino acid differences were found between both clades in the C/prM region at position 100 (Lys vs. Arg) and in the E/NS1 region at positions 722 (Ala vs. Thr). Although the geographic movement of DEN-1 virus can not be unequivocally traced from the genetic relationship determined here, our results suggest that the recent epidemics in Argentina and Paraguay were due to the re-emergence of a previously circulating strain, or to the virus circulating unnoticed, rather than to the introduction of a new genotype.
Assuntos
Vírus da Dengue/classificação , Sequência de Aminoácidos , Argentina , Vírus da Dengue/genética , Genótipo , Dados de Sequência Molecular , Paraguai , Filogenia , Proteínas do Envelope Viral/química , Proteínas não Estruturais Virais/químicaRESUMO
BACKGROUND: Since 1993 the Pan American Health Organization has coordinated a surveillance network with the National Reference Laboratories of Argentina, Brazil, Chile, Colombia, Mexico and Uruguay aimed at monitoring capsular types and antimicrobial susceptibility of Streptococcus pneumoniae causing invasive disease in children <6 years of age. METHODS: The surveillance system included children 6 years of age and younger with invasive disease caused by S. pneumoniae. The identification, capsular typing and susceptibility to penicillin of the isolates were conducted using a common protocol, based on standard methodologies. RESULTS: By June, 1999, 4,105 invasive pneumococcal isolates had been collected mainly from pneumonia (44.1%) and meningitis (41.1%) cases. Thirteen capsular types accounting for 86.1% of the isolates (14, 6A/6B, 5, 1, 23F, 19F, 18C, 19A, 9V, 7F, 3, 9N and 4) remained the most common types during the surveillance period. Diminished susceptibility to penicillin was detected in 28.6% of the isolates, 17.3% with intermediate and 11.3% with high level resistance. Resistance varied among countries and increased during this period in Argentina, Colombia and Uruguay. Serotypes 14 and 23F accounted for 66.6% of the resistance. CONCLUSION: These surveillance data clearly demonstrate the potential impact of the introduction of a conjugate vaccine on pneumococcal disease and the need for more judicious use of antibiotics to slow or reverse the development of antimicrobial resistance.
Assuntos
Resistência às Penicilinas , Penicilinas/administração & dosagem , Infecções Pneumocócicas/tratamento farmacológico , Streptococcus pneumoniae/efeitos dos fármacos , Criança , Pré-Escolar , Feminino , Humanos , Lactente , Modelos Logísticos , Masculino , México , Penicilinas/uso terapêutico , Vigilância da População , Garantia da Qualidade dos Cuidados de Saúde , Controle de Qualidade , Sorotipagem , América do Sul , Streptococcus pneumoniae/classificaçãoRESUMO
In 1998, a dengue outbreak (serotype 2) occurred in Salta province in Northern Argentina, following the first detection of dengue in the same area in 1997. We classified the serologic response of cases from 1998 as primary or secondary, since the risk of severe disease is greater for secondary cases. We studied 154 cases by plaque reduction neutralization and hemagglutination inhibition tests. Thirty-eight cases (25%) were classified as primary serologic responses and 84 cases (54%) as secondary responses. Thirty-two cases (21%) with borderline IgG titers could not be classified. Previous exposure to potentially cross-reacting flaviviruses (Saint Louis Encephalitis [SLE] and Yellow Fever [YF] viruses) was analyzed, as a possible cause of the secondary response pattern. Our results indicated that among cases classified as dengue secondary response, 83% could be attributed to previous SLE or YF exposure or serologic cross-reactivity. Vaccination against YF virus was at most a minor contributor to the secondary response pattern. The finding of a positive YF serologic result among persons not vaccinated may indicate silent circulation of YF in a region that can support both urban and jungle cycles. Other cases showing dengue secondary responses remained unexplained, suggesting the unrecognized occurrence of a previous infection with other dengue serotypes or of flaviviruses other than SLE or YF.
Assuntos
Anticorpos Antivirais/sangue , Vírus da Dengue/imunologia , Dengue/imunologia , Encefalite de St. Louis/imunologia , Febre Amarela/imunologia , Anticorpos Antivirais/imunologia , Argentina/epidemiologia , Dengue/epidemiologia , Dengue/virologia , Vírus da Dengue/isolamento & purificação , Surtos de Doenças , Encefalite de St. Louis/sangue , Ensaio de Imunoadsorção Enzimática , Humanos , Imunoglobulina G/imunologia , Imunoglobulina M/imunologia , Febre Amarela/sangue , Vacina contra Febre AmarelaRESUMO
In 1998, a dengue outbreak (serotype 2) occurred in Salta province in Northern Argentina, following the first detection of dengue in the same area in 1997. We classified the serologic response of cases from 1998 as primary or secondary, since the risk of severe disease is greater for secondary cases. We studied 154 cases by plaque reduction neutralization and hemagglutination inhibition tests. Thirty-eight cases (25
) were classified as primary serologic responses and 84 cases (54
) as secondary responses. Thirty-two cases (21
) with borderline IgG titers could not be classified. Previous exposure to potentially cross-reacting flaviviruses (Saint Louis Encephalitis [SLE] and Yellow Fever [YF] viruses) was analyzed, as a possible cause of the secondary response pattern. Our results indicated that among cases classified as dengue secondary response, 83
could be attributed to previous SLE or YF exposure or serologic cross-reactivity. Vaccination against YF virus was at most a minor contributor to the secondary response pattern. The finding of a positive YF serologic result among persons not vaccinated may indicate silent circulation of YF in a region that can support both urban and jungle cycles. Other cases showing dengue secondary responses remained unexplained, suggesting the unrecognized occurrence of a previous infection with other dengue serotypes or of flaviviruses other than SLE or YF.
RESUMO
In Argentina, reinfestation with Aedes aegypti was registered in 1986. At present, the mosquito is well established in 10 provinces, from Buenos Aires up to the country's northern frontiers. This paper presents estimates of genetic variability in Ae. aegypti populations from central Argentina and determinations of genetic distances among them. We analyzed allozymic frequencies at 11 loci in samples from 3 localities. The proportion of polymorphic loci varied between 27.3 and 63.6. Expected mean heterozygosity ranged from 0.090 to 0.161 and Rogers' similarity among samples ranged between 0.909 and 0.958. The lack of relationship between genetic and geographic distances is in agreement with a recent colonization of the studied area. The mean Wright's coefficient FST value (0.065) indicates low levels of genetic differentiation among populations from different localities. Given the recent reinfestation with this mosquito in Argentina, the high levels of polymorphism found could indicate multiple introductions of representative samples from genetically different subpopulations.
Assuntos
Aedes/genética , Genética Populacional , Isoenzimas/genética , Aedes/enzimologia , Alelos , Animais , Argentina , Variação Genética/genética , Heterozigoto , Polimorfismo Genético/genéticaAssuntos
Dengue/epidemiologia , Adolescente , Adulto , Aedes/virologia , Idoso , Animais , Argentina/epidemiologia , Dengue/transmissão , Surtos de Doenças , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , ViagemRESUMO
Dengue (DEN) reemergence was first detected in Salta, Argentina, in 1997. It was confirmed by serology and PCR that DEN-2 virus was responsible for sporadic cases and indigenous transmission. A laboratory-based surveillance system allowed the detection of an outbreak in Salta several months later. In total, 378 DEN cases were laboratory diagnosed out of 646 (58%) studied. The cases were distributed in 10 localities of the province between January 3rd and May 31st, 1998. One DEN-2 viral isolation and 4 PCR products were obtained from patients coming from Orán and Embarcación localities. Male and female cases occurred at a similar rate (1:1), with adult cases (82.5%) nearly five times greater than for children under 15 years-old (17.5%). Clinically, all cases corresponded to classic DEN. This is the first time that a DEN outbreak has been laboratory-diagnosed in Argentina and also the first time that DEN virus has been isolated in this country.
Assuntos
Vírus da Dengue/isolamento & purificação , Dengue/epidemiologia , Surtos de Doenças , Adolescente , Adulto , Idoso , Argentina/epidemiologia , Criança , Dengue/diagnóstico , Dengue/virologia , Vírus da Dengue/classificação , Ensaio de Imunoadsorção Enzimática , Feminino , Testes de Hemaglutinação , Humanos , Masculino , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase , Vigilância da População , Estudos SoroepidemiológicosRESUMO
OBJECTIVES: To determine the value of color flow imaging in the prenatal differentiation of solid placental masses protruding from the fetal surface of the placenta. METHODS: Seven pregnancies in which a large solid mass was seen on the fetal surface of the placenta were prospectively studied. Color flow imaging was used to identify vessels within the mass and the prenatal ultrasound finding correlated with placental pathology. RESULTS: Postpartum examination of the placenta revealed four cases of chorioangioma, two cases of subchorionic thrombohematoma and one case of subamniotic hematoma. Prenatal ultrasound using color flow imaging correctly identified all cases of placental chorioangioma by the demonstration of blood flow within the mass. Conversely, absence of blood flow signals was invariably documented in both cases of subchorionic thrombohematoma and in the single case of subamniotic hematoma. Among the four cases of chorioangioma, two developed complications requiring delivery. No complications were noted in cases of avascular placental masses in this series. CONCLUSIONS: Color Doppler ultrasound plays an important role in the prenatal evaluation of solid placental masses. This technique allows the identification of those cases at increased risk of pregnancy complications which need close monitoring throughout gestation.
Assuntos
Hemangioma/diagnóstico por imagem , Hematoma/diagnóstico por imagem , Doenças Placentárias/diagnóstico por imagem , Complicações Neoplásicas na Gravidez/diagnóstico por imagem , Ultrassonografia Pré-Natal , Adulto , Feminino , Humanos , Gravidez , Estudos Prospectivos , Ultrassonografia Doppler em CoresRESUMO
Dengue (DEN) reemergence was first detected in Salta, Argentina, in 1997. It was confirmed by serology and PCR that DEN-2 virus was responsible for sporadic cases and indigenous transmission. A laboratory-based surveillance system allowed the detection of an outbreak in Salta several months later. In total, 378 DEN cases were laboratory diagnosed out of 646 (58
) studied. The cases were distributed in 10 localities of the province between January 3rd and May 31st, 1998. One DEN-2 viral isolation and 4 PCR products were obtained from patients coming from Orán and Embarcación localities. Male and female cases occurred at a similar rate (1:1), with adult cases (82.5
) nearly five times greater than for children under 15 years-old (17.5
). Clinically, all cases corresponded to classic DEN. This is the first time that a DEN outbreak has been laboratory-diagnosed in Argentina and also the first time that DEN virus has been isolated in this country.
RESUMO
Aedes aegypti, eradicated from Argentina in 1963, has now reinfested the country as far south as Buenos Aires. In 1997, four persons with travel histories to Brazil, Ecuador, or Venezuela had confirmed dengue, and surveillance for indigenous transmission allowed the detection of 19 dengue cases in Salta Province. These cases of dengue are the first in Argentina since 1916 and represent a new southern extension of dengue virus.
Assuntos
Dengue/epidemiologia , Surtos de Doenças , Aedes , Animais , Argentina/epidemiologia , Dengue/sangue , Dengue/fisiopatologia , Dengue/virologia , Vírus da Dengue/genética , Vírus da Dengue/imunologiaRESUMO
During a surveillance study to determine the relative prevalence of capsular types of Streptococcus pneumoniae and antimicrobial susceptibility of invasive isolates in children <5 years old in Mexico City, 220 isolates were collected. The serotype 23F was the most common found, followed by types 6A + B, 14, 19F, and 19A. Diminished susceptibility to penicillin was detected in 106 isolates (48.2%), and high penicillin resistance was found in 49 strains (22.2%), 31 belonging to type 23F. Resistance was also observed to erythromycin (13.1%), to chloramphenicol (43.1%), and to cefotaxime (10.9%). No strains were resistant to ofloxacin or vancomycin. Forty-four of the highly penicillin resistant isolates (penicillin MIC > or =2.0 microg/ml) were examined with molecular fingerprinting techniques; 29 (65.9%) of these isolates (all except two strains) were serotype 23F and shared subtype variants of PFGE type A characteristic of the internationally spread Spanish/USA clone of S. pneumoniae. These strains were also resistant to trimethoprim/sulfametoxasole (TMP/SMX), chloramphenicol, and tetracycline, and most of them were susceptible to erythromycin. Another 6 of the highly penicillin-resistant strains (serogroups 9 and 14) showed PFGE fingerprints and antimicrobial susceptibility pattern characteristic of a second internationally spread clone (French/Spanish clone) and carried resistance to penicillin and TMP/SMX. The rest of the 9 penicillin-resistant isolates were represented by 7 distinct additional PFGE types. The findings suggest that almost 80% of all highly penicillin resistant strains may have been "imported" into Mexico.
Assuntos
Resistência a Múltiplos Medicamentos/genética , Infecções Estreptocócicas/microbiologia , Streptococcus pneumoniae/isolamento & purificação , Pré-Escolar , Resistência Microbiana a Medicamentos/genética , Eletroforese em Gel de Campo Pulsado , Humanos , México/epidemiologia , Testes de Sensibilidade Microbiana , Sorotipagem , Infecções Estreptocócicas/epidemiologia , Streptococcus pneumoniae/efeitos dos fármacos , Streptococcus pneumoniae/genéticaRESUMO
As part of the Sistema Regional de Vacunas (SIREVA) initiative, we conducted a surveillance study to determine the relative prevalence of capsular types of Streptococcus pneumoniae and antimicrobial susceptibility of invasive isolates in children less than 5 years old. We collected 220 isolates and found 33 of the 90 known types, with type 23F as the most common followed by types 6A+B, 14, 19F, and 19A. High penicillin resistance was found in 49 strains (22.2%), 31 belonging to type 23F. Twenty-nine (13.1%) were resistant to erythromycin, 95 (43.1%) were resistant to chloramphenicol, and 24 (10.9%) were resistant to cefotaxime. No strains were resistant to vancomycin.