RESUMEN
Selection pressures exerted on Staphylococcus aureus by host factors during infection may lead to the emergence of regulatory phenotypes better adapted to the infection site. Traits convenient for persistence may be fixed by mutation thus turning these mutants into microevolution endpoints. The feasibility that stable, non-encapsulated S. aureus mutants can regain expression of key virulence factors for survival in the bloodstream was investigated. S. aureus agr mutant HU-14 (IS256 insertion in agrC) from a patient with chronic osteomyelitis was passed through the bloodstream using a bacteriemia mouse model and derivative P3.1 was obtained. Although IS256 remained inserted in agrC, P3.1 regained production of capsular polysaccharide type 5 (CP5) and staphyloxanthin. Furthermore, P3.1 expressed higher levels of asp23/SigB when compared with parental strain HU-14. Strain P3.1 displayed decreased osteoclastogenesis capacity, thus indicating decreased adaptability to bone compared with strain HU-14 and exhibited a trend to be more virulent than parental strain HU-14. Strain P3.1 exhibited the loss of one IS256 copy, which was originally located in the HU-14 noncoding region between dnaG (DNA primase) and rpoD (sigA). This loss may be associated with the observed phenotype change but the mechanism remains unknown. In conclusion, S. aureus organisms that escape the infected bone may recover the expression of key virulence factors through a rapid microevolution pathway involving SigB regulation of key virulence factors.
Asunto(s)
Cápsulas Bacterianas/metabolismo , Proteínas Bacterianas/genética , Staphylococcus aureus/genética , Transactivadores/genética , Xantófilas/metabolismo , Adulto , Animales , Antibacterianos/farmacología , Bacteriemia/microbiología , Cápsulas Bacterianas/genética , Modelos Animales de Enfermedad , Farmacorresistencia Bacteriana Múltiple/genética , Regulación Bacteriana de la Expresión Génica/genética , Humanos , Masculino , Ratones , Osteomielitis/microbiología , Eliminación de Secuencia/genética , Staphylococcus aureus/aislamiento & purificación , Staphylococcus aureus/patogenicidad , Virulencia/genética , Factores de Virulencia/genéticaRESUMEN
BACKGROUND: Emergence of viral resistance is a major obstacle for antiretroviral treatment (ART) effectiveness. Human immunodeficiency virus type-1 (HIV-1) variants and drug-resistance mutations were identified in naive and antiretroviral drug-experienced children with virologic failure, in Honduras and El Salvador. METHODS: Dried blood spots (DBS) from 80 individuals (54 from Honduras, 26 from El Salvador) infected during their childhood between 1989 and 2009 were collected in 2009. The HIV pol region was amplified and sequenced to identify antiretroviral-resistant mutations according to the 2009 International AIDS Society. The genotypic drug resistance interpretation was performed using the Stanford algorithm. HIV-1 variants were characterized by phylogenetic analysis and subtyping tools. RESULTS: HIV-1 protease and reverse transcription sequences were obtained from DBS specimens in 71 and 66 patients, respectively, of the 80 patients. All children were native Central Americans carrying subtype B, with a mean age of 9 years, most were male (65%), perinatally infected (96%), with moderate/severe AIDS symptoms (70%), and receiving first line ART at the time of sequencing (65%). Diagnostic delay was frequently observed. Infected children from Honduras presented longer ART experience and clinical outcomes, and more frequent severe symptoms. Resistant variants infected 1 of 11 naive children from El Salvador but none of the perinatally infected naive children from Honduras. Resistance was higher among ART-exposed individuals in both countries and similar for protease inhibitors (16%), nucleoside reverse transcription inhibitors (44%-52%), and nonnucleoside reverse-transcription inhibitors (66.7%). One in 10 pretreated children in each country was infected with resistant viruses to the 3 drug families. CONCLUSIONS: Our data support the need for continued surveillance of resistance patterns using DBS at national levels among naive and pretreated children to optimize the ART regimens.
Asunto(s)
Fármacos Anti-VIH/farmacología , Farmacorresistencia Viral , Infecciones por VIH/epidemiología , Infecciones por VIH/virología , VIH-1/efectos de los fármacos , Adolescente , Sangre/virología , Niño , Preescolar , El Salvador/epidemiología , Femenino , Genotipo , VIH-1/aislamiento & purificación , Honduras/epidemiología , Humanos , Lactante , Recién Nacido , Masculino , Mutación Missense , Prevalencia , ARN Viral/genética , Análisis de Secuencia de ADN , Insuficiencia del Tratamiento , Productos del Gen pol del Virus de la Inmunodeficiencia Humana/genéticaRESUMEN
Although HIV-1 clade B variants are predominant in Western Europe, non-B subtypes are rapidly spreading, mainly due to immigration from endemic regions. All newly diagnosed HIV-1-infected individuals at a HIV/AIDS clinic in Madrid from 2000 to 2007 were identified. Subtype assignment was based on phylogenetic analysis of pol sequences from plasma specimens collected at first visit. A total of 1,430 newly diagnosed HIV-1 individuals were identified: 902 Spaniards, 232 South Americans, and 162 Africans, among others. The proportion of South-Americans and Africans among diagnosed HIV-1 patients increased from 2000 to 2007 (from 17% to 22% and from 4% to 21%, respectively). Half of diagnosis of HIV-1 in 2007 was in foreigners whereas in previous years Spaniards were predominant. Non-B variants were found in 157 (24%) of the 649 subjects who could be subtyped: 11A, 6C, 2D, 1F2, 13G, 4H, 1J, 3CRF01_AE, 64CRF02_AG, 2CRF03_AB, 3CRF06_cpx, 3CRF10_CD, 7CRF11_cpx, 9CRF12_BF, 9CRF14_BG, 1CRF18_cpx, 1CRF19_cpx, 2CRF31_BC, 10 URF and 5 outgroups. They represented 93%, 14% and 4% of newly-diagnosed HIV-1 Africans, South-Americans and native Spaniards, respectively. Non-B subtypes increased from 9% in 2000 to 32% in 2007, specially among South-Americans (from 11% to 20%) and native Spaniards (from 4% to 10%). Most (75%) were recombinant viruses. The highest number and diversity of HIV-1 variants among natives was observed in 2007. HIV-1 non-B subtypes are increasingly present among newly diagnosed HIV-1 individuals in Madrid, representing a third of cases in 2007, whereas 10% of newly diagnosed HIV-1 native Spaniards had non-B viruses.