Different chemical alternatives were evaluated for obtaining immunogenic polypeptidic macromolecu... more Different chemical alternatives were evaluated for obtaining immunogenic polypeptidic macromolecules which could then be used as vaccines. These were based on the ligation reaction between an unprotected immunogenic peptide and an unprotected multifunctional core peptide; polyantigens, designated dendrimers because their form resembles that of dendritic cells, were thus obtained. The antigen-core ligation alternatives, studied by indirect synthesis, were the formation of oxime, hydrazone and thiazolidine linkages, making use of the reaction between a weak base (acting as nucleophile) and an alkyl aldehyde. The other alternative was the formation of a thioether linkage between a sulfydryl and an alkyl halide. Finally, a multiple antigen peptide (MAP) was synthesized by direct synthesis. All reactions were monitored by SEC-HPLC and SDS-PAGE. Dendrimer molecular mass obtained was confirmed by MS MALDI-TOF. Dendrimer purification was first carried out by concentrating crude reaction products with CP-5000 centricons and (using SEC-HPLC) pure tetramers were then obtained. A 20-residue 9376 immunogenic sequence, from Plasmodium falciparum apical merozoite antigen protein (AMA-1), was used to study the best alternative for chemical ligation. It was observed that thiazolidine formation proceeded with greater yield and in less time than the others. A tetramer has been simultaneously synthesized via thiazolidine with the SPf-66 antimalarial vaccine 45-residue monomer, proving the technique's versatility. The 9376 peptide disulfide bound polymer and SPf-66 (as well as their tetrameric thiazolidine dendrimers) were inoculated in rabbits to evaluate their antibody response. It was observed that titers for tetrameric thiazolidine dendrimers were not just greater but were also sustained over time. Western blot for pre-immune and immune sera showed that dendrimer sera recognized specific Plasmodium falciparum proteins as well as disulfide-bound polymers.
We calculated the cost of an established tele-ophthalmology service, from a health-provider&a... more We calculated the cost of an established tele-ophthalmology service, from a health-provider's perspective, and compared this with the cost of three other existing eye-care service delivery options. During a 12-month study period, 118 persons took part in the tele-ophthalmology consultations between a rural clinic located approximately 900 km from the Lions Eye Institute in Perth. The variable costs of tele-ophthalmology were 166.89 dollars(Australian dollars) per patient, and the alternatives cost 445.96 dollars, 271.48 dollars and 665.44 dollars per patient. Tele-ophthalmology incurred a set-up cost of 13,340 dollars. The threshold at which tele-ophthalmology became cheaper than any of the alternative options occurred at a workload of 128 patients. Tele-ophthalmology offers a viable alternative to conventional eye-care service in rural and remote areas.
Staphylococcus hominis is a commensal resident of human skin and an opportunistic pathogen. The s... more Staphylococcus hominis is a commensal resident of human skin and an opportunistic pathogen. The species is subdivided into two subspecies, S. hominis subsp. hominis and S. hominis subsp. novobiosepticus, which are difficult to distinguish. To investigate the evolution and epidemiology of S. hominis, a total of 108 isolates collected from 10 countries over 40 years were characterized by classical phenotypic methods and genetic methods. One nonsynonymous mutation in gyrB, scored with a novel SNP typing assay, had a perfect association with the novobiocin-resistant phenotype. A multilocus sequence typing (MLST) scheme was developed from six housekeeping gene fragments, and revealed relatively high levels of genetic diversity and a significant impact of recombination on S. hominis population structure. Among the 40 sequence types (STs) identified by MLST, three STs (ST2, ST16 and ST23) were S. hominis subsp. novobiosepticus, and they distinguished between isolates from different outbreaks, whereas 37 other STs were S. hominis subsp. hominis, one of which was widely disseminated (ST1). A modified PCR assay was developed to detect the presence of ccrAB4 from the SCCmec genetic element. S. hominis subsp. novobiosepticus isolates were oxacillin-resistant and carriers of specific components of SCCmec (mecA class A, ccrAB3, ccrAB4, ccrC), whereas S. hominis subsp. hominis included both oxacillin-sensitive and -resistant isolates and a more diverse array of SCCmec components. Surprisingly, phylogenetic analyses indicated that S. hominis subsp. novobiosepticus may be a polyphyletic and, hence, artificial taxon. In summary, these results revealed the genetic diversity of S. hominis, the identities of outbreak-causing clones, and the evolutionary relationships between subspecies and clones. The pathogenic lifestyle attributed to S. hominis subsp. novobiosepticus may have originated on more than one occasion.
We report a rare case of human intestinal capillariasis in a young Colombian man who presented wi... more We report a rare case of human intestinal capillariasis in a young Colombian man who presented with abdominal pain and mild, self-limited diarrhea. Capillaria eggs were visualized in the feces, and treatment with mebendazole (200 mg/d for 3 weeks) resulted in clinical and parasitological cure. To our knowledge, this is the first case in a South American person and the second case reported in Europe. This case highlights the acquisition of endemic intestinal parasitosis far away from classically considered areas of endemicity. We review the English-language literature on human intestinal capillariasis and compare findings from other cases with those from the current case.
... JIF MartõÂn, Fernando Dronda,* and F. Chaves² Servicio MeÂdico del Centro Penitenciario Madri... more ... JIF MartõÂn, Fernando Dronda,* and F. Chaves² Servicio MeÂdico del Centro Penitenciario Madrid-2, C/San Isidro,6; 38D, 28807, Alcala de Henares, Madrid, Spain, *Hospital RamoÂn y Cajal de Madrid, Spain, and ²Hospital 12 de Octubre de ... 3 Katz SI, Gallin JI, Hertz KC et al ...
Staphylococcus aureus is the main causal agent of infectious endocarditis (IE) in intravenous dru... more Staphylococcus aureus is the main causal agent of infectious endocarditis (IE) in intravenous drug addicts (IVDA) with most of the strains, isolated in Spain being resistant to penicillin and sensitive to methycillin, although the latter condition varied in recent years. Two cases of IE caused by S. aureus strains sensitive to penicillin in IVDA are presented. All bacteremia episodes diagnosed in the Hospital General Penitenciario (Madrid) over a 33-month period (March 1991 to December 1993) were prospectively studied. Special attention was given to patients diagnosed of IE. Blood cultures were processed according to the usual technique by a non radiometric system. One hundred and four bacteremias were detected with 14 being produced by S. aureus. Ten episodes of the total number of bacteremias fulfilled criteria for IE with 2 being produced by strains of S. aureus sensitive to penicillin (CMI < 0.06 mu/ml). Both patients had coinfection by HIV. The clinical evolution prior to diagnosis was prolonged although clinical and microbiologic cure were achieved with intravenous beta-lactam antibiotics treatment, without complications. Despite the low incidence of the isolation of Staphylococcus aureus sensitive to penicillin (< 3%) recently observed in Spain, strains producing severe infections, showing patterns of sensitivity such as those found during the preantibiotic era, may still be isolated.
To investigate the diversity of IS6110 fingerprints of Mycobacterium tuberculosis isolates in the... more To investigate the diversity of IS6110 fingerprints of Mycobacterium tuberculosis isolates in the United States and to determine if matching IS6110 fingerprints represent recent interstate tuberculosis transmission, we performed restriction fragment length polymorphism analysis of M. tuberculosis isolates from 1,326 patients in three geographically separated states. Seven hundred ninety-five different IS6110 fingerprint patterns were generated, and pattern diversity was similar in each state. Ninety-six percent of the fingerprint patterns were observed in only one state, demonstrating that most IS6110 fingerprint patterns are confined to a single geographic location. Of the IS6110 fingerprint patterns that were shared by isolates from more than one state, most isolates with 1 to 5 IS6110 copies were separable by pTBN12 fingerprinting whereas those with >15 copies were not. One high-copy-number M. tuberculosis strain had identical IS6110 and pTBN12 fingerprints and included 57 isolates from three states. Epidemiological data demonstrated significant recent transmission of tuberculosis within each city but not among the states. This suggests that identical fingerprints of isolates from geographically separate locations most likely reflect interstate tuberculosis transmission in the past, with subsequent intrastate spread of disease. Further evaluation of M. tuberculosis strains that cause outbreaks in different geographic locations will provide insight into the epidemiological and bacteriological factors that facilitate the spread of tuberculosis.
A comparison was made between DNA fingerprints of Mycobacterium tuberculosis produced with the in... more A comparison was made between DNA fingerprints of Mycobacterium tuberculosis produced with the insertion sequence IS6110 and those produced with the polymorphic GC-rich repetitive sequence contained in the plasmid pTBN12. A total of 302 M. tuberculosis isolates from the prison system in Madrid, Spain, and the Denver Public Health Department (Denver, Colo.) were analyzed with the two probes. Both probes identified the same isolates in the same clusters when the fingerprints had six or more copies of IS6110. Analysis of isolates with unique IS6110 fingerprints demonstrated that they were unique with pTBN12. The pTBN12 probe had greater discriminating power in isolates having five or fewer copies of IS6110. Forty-seven isolates from Denver having fewer than five copies of IS6110 which were grouped in 11 clusters with identical fingerprint patterns were subdivided into 35 different patterns by pTBN12. Isolates with IS6110 fingerprints with more than six copies of IS6110 that differed fr...
We report the complete genome sequence of Acinetobacter baumannii strain AbH12O-A2, isolated duri... more We report the complete genome sequence of Acinetobacter baumannii strain AbH12O-A2, isolated during a large outbreak in Spain. The genome has 3,875,775 bp and 3,526 coding sequences, with 39.4% G؉C content. The availability of this genome will facilitate the study of the pathogenicity of the Acinetobacter species.
Genetic alterations in the rpoB gene were characterized in 50 rifampin-resistant (Rif r ) clinica... more Genetic alterations in the rpoB gene were characterized in 50 rifampin-resistant (Rif r ) clinical isolates of Mycobacterium tuberculosis complex from Spain. A rapid PCR-enzyme-linked immunosorbent assay (ELISA) technique for the identification of rpoB mutations was evaluated with isolates of the M. tuberculosis complex and clinical specimens from tuberculosis patients that were positive for acid-fast bacilli (AFB). Sequence analysis demonstrated 11 different rpoB mutations among the Rif r isolates in the study. The most frequent mutations were those associated with codon 531 (24 of 50; 48%) and codon 526 (11 of 50; 22%). Although the PCR-ELISA does not permit characterization of the specific Rif r allele within each strain, 10 of the 11 Rif r genotypes were correctly identified by this method. We used the PCR-ELISA to predict the rifampin susceptibility of M. tuberculosis complex organisms from 30 AFB-positive sputum specimens. For 28 samples, of which 9 contained Rif r organisms and 19 contained susceptible strains, results were concordant with those based on culturebased drug susceptibility testing and sequencing. Results from the remaining two samples could not be interpreted because of low bacillary load (microscopy score of 1؉ for 1 to 9 microorganisms/100 fields). Our results suggest that the PCR-ELISA is an easy technique to implement and could be used as a rapid procedure for detecting rifampin resistance to complement conventional culture-based methods.
... Marıa Soledad Cuétara,1 Almudena Alhambra,2 Fernando Chaves,2 Marıa Dolores Moragues,3 José P... more ... Marıa Soledad Cuétara,1 Almudena Alhambra,2 Fernando Chaves,2 Marıa Dolores Moragues,3 José Pontón,4 and Amalia del Palacio2 1Servicios de Microbiologıa, Hospital Severo Ochoa, and 2Hospital ... Washington, DC: American Society for Microbiology, 2006:425. ...
The resistance of Acinetobacter baumannii strains to carbapenems is a worrying problem in hospita... more The resistance of Acinetobacter baumannii strains to carbapenems is a worrying problem in hospital settings. The main mechanism of carbapenem resistance is the expression of β-lactamases (metalloenzymes or class D enzymes). The mechanisms of the dissemination of these genes among A. baumannii strains are not fully understood. In this study we used two carbapenem-resistant clinical strains of A. baumannii (AbH12O-A2 and AbH12O-CU3) expressing the plasmid-borne bla(OXA-24) gene (plasmids pMMA2 and pMMCU3, respectively) to demonstrate that A. baumannii releases outer membrane vesicles (OMVs) during in vitro growth. The use of hybridization studies enabled us to show that these OMVs harbored the bla(OXA-24) gene. The incubation of these OMVs with the carbapenem-susceptible A. baumannii ATCC 17978 host strain yielded full resistance to carbapenems. The presence of the original plasmids harboring the bla(OXA-24) gene was detected in strain ATCC 17978 after the transformation of OMVs. New OMVs harboring bla(OXA-24) were released by A. baumannii ATCC 17978 after it was transformed with the original OMV-mediated plasmids, indicating the universality of the process. We present the first experimental evidence that clinical isolates of A. baumannii may release OMVs as a mechanism of horizontal gene transfer whereby carbapenem resistance genes are delivered to surrounding A. baumannii bacterial isolates.
Toxicon : official journal of the International Society on Toxinology, 1981
Neutralization of lethality, myonecrosis, hemorrhage and edema induced by Bothrops asper venom in... more Neutralization of lethality, myonecrosis, hemorrhage and edema induced by Bothrops asper venom in mice was studied using the polyvalent antivenom produced in the Instituto Clodomiro Picado. The neutralizing effect (ED50) on each of these toxic activities varied; the neutralization of lethal and hemorrhagic effects being more effective than the neutralization of myonecrosis and edema. With independent inoculation of venom and antivenom, antivenom was not effective in neutralizing edema-forming activity. The myonecrotic effect was only partially neutralized when serum was given i.v. immediately after envenomation; however, antivenin effectively neutralized the hemorrhagic activity. The ineffectiveness of antivenom in neutralizing edema and myonecrosis could be partially explained by the rapid development of these effects. Hence, the time interval between envenomation and antivenom administration and the route of serum administration both play an important role in the neutralization of...
The American journal of tropical medicine and hygiene
The effectiveness of the chelating agent CaNa2EDTA and the peptidomimetic matrix metalloproteinas... more The effectiveness of the chelating agent CaNa2EDTA and the peptidomimetic matrix metalloproteinase inhibitor batimastat (BB-94) to inhibit local tissue damage induced by Bothrops asper snake venom was studied in mice. Both compounds totally inhibited proteolytic, hemorrhagic, and dermonecrotic effects, and partially reduced edema-forming activity, when incubated with venom prior to injection. Much lower concentrations of batimastat than of CaNa2EDTA were required to inhibit these effects. In addition, batimastat, but not CaNa2EDTA, partially reduced myotoxic activity of the venom. When the inhibitors were administered at various time intervals after envenomation at the same site of venom injection, both compounds were effective in neutralizing local hemorrhage and dermonecrosis if administered rapidly after venom. Inhibition was not as effective as the time lapse between venom and inhibitor injections increased. Owing to the relevance of metalloproteinases in the pathogenesis of loc...
Different chemical alternatives were evaluated for obtaining immunogenic polypeptidic macromolecu... more Different chemical alternatives were evaluated for obtaining immunogenic polypeptidic macromolecules which could then be used as vaccines. These were based on the ligation reaction between an unprotected immunogenic peptide and an unprotected multifunctional core peptide; polyantigens, designated dendrimers because their form resembles that of dendritic cells, were thus obtained. The antigen-core ligation alternatives, studied by indirect synthesis, were the formation of oxime, hydrazone and thiazolidine linkages, making use of the reaction between a weak base (acting as nucleophile) and an alkyl aldehyde. The other alternative was the formation of a thioether linkage between a sulfydryl and an alkyl halide. Finally, a multiple antigen peptide (MAP) was synthesized by direct synthesis. All reactions were monitored by SEC-HPLC and SDS-PAGE. Dendrimer molecular mass obtained was confirmed by MS MALDI-TOF. Dendrimer purification was first carried out by concentrating crude reaction products with CP-5000 centricons and (using SEC-HPLC) pure tetramers were then obtained. A 20-residue 9376 immunogenic sequence, from Plasmodium falciparum apical merozoite antigen protein (AMA-1), was used to study the best alternative for chemical ligation. It was observed that thiazolidine formation proceeded with greater yield and in less time than the others. A tetramer has been simultaneously synthesized via thiazolidine with the SPf-66 antimalarial vaccine 45-residue monomer, proving the technique's versatility. The 9376 peptide disulfide bound polymer and SPf-66 (as well as their tetrameric thiazolidine dendrimers) were inoculated in rabbits to evaluate their antibody response. It was observed that titers for tetrameric thiazolidine dendrimers were not just greater but were also sustained over time. Western blot for pre-immune and immune sera showed that dendrimer sera recognized specific Plasmodium falciparum proteins as well as disulfide-bound polymers.
We calculated the cost of an established tele-ophthalmology service, from a health-provider&a... more We calculated the cost of an established tele-ophthalmology service, from a health-provider's perspective, and compared this with the cost of three other existing eye-care service delivery options. During a 12-month study period, 118 persons took part in the tele-ophthalmology consultations between a rural clinic located approximately 900 km from the Lions Eye Institute in Perth. The variable costs of tele-ophthalmology were 166.89 dollars(Australian dollars) per patient, and the alternatives cost 445.96 dollars, 271.48 dollars and 665.44 dollars per patient. Tele-ophthalmology incurred a set-up cost of 13,340 dollars. The threshold at which tele-ophthalmology became cheaper than any of the alternative options occurred at a workload of 128 patients. Tele-ophthalmology offers a viable alternative to conventional eye-care service in rural and remote areas.
Staphylococcus hominis is a commensal resident of human skin and an opportunistic pathogen. The s... more Staphylococcus hominis is a commensal resident of human skin and an opportunistic pathogen. The species is subdivided into two subspecies, S. hominis subsp. hominis and S. hominis subsp. novobiosepticus, which are difficult to distinguish. To investigate the evolution and epidemiology of S. hominis, a total of 108 isolates collected from 10 countries over 40 years were characterized by classical phenotypic methods and genetic methods. One nonsynonymous mutation in gyrB, scored with a novel SNP typing assay, had a perfect association with the novobiocin-resistant phenotype. A multilocus sequence typing (MLST) scheme was developed from six housekeeping gene fragments, and revealed relatively high levels of genetic diversity and a significant impact of recombination on S. hominis population structure. Among the 40 sequence types (STs) identified by MLST, three STs (ST2, ST16 and ST23) were S. hominis subsp. novobiosepticus, and they distinguished between isolates from different outbreaks, whereas 37 other STs were S. hominis subsp. hominis, one of which was widely disseminated (ST1). A modified PCR assay was developed to detect the presence of ccrAB4 from the SCCmec genetic element. S. hominis subsp. novobiosepticus isolates were oxacillin-resistant and carriers of specific components of SCCmec (mecA class A, ccrAB3, ccrAB4, ccrC), whereas S. hominis subsp. hominis included both oxacillin-sensitive and -resistant isolates and a more diverse array of SCCmec components. Surprisingly, phylogenetic analyses indicated that S. hominis subsp. novobiosepticus may be a polyphyletic and, hence, artificial taxon. In summary, these results revealed the genetic diversity of S. hominis, the identities of outbreak-causing clones, and the evolutionary relationships between subspecies and clones. The pathogenic lifestyle attributed to S. hominis subsp. novobiosepticus may have originated on more than one occasion.
We report a rare case of human intestinal capillariasis in a young Colombian man who presented wi... more We report a rare case of human intestinal capillariasis in a young Colombian man who presented with abdominal pain and mild, self-limited diarrhea. Capillaria eggs were visualized in the feces, and treatment with mebendazole (200 mg/d for 3 weeks) resulted in clinical and parasitological cure. To our knowledge, this is the first case in a South American person and the second case reported in Europe. This case highlights the acquisition of endemic intestinal parasitosis far away from classically considered areas of endemicity. We review the English-language literature on human intestinal capillariasis and compare findings from other cases with those from the current case.
... JIF MartõÂn, Fernando Dronda,* and F. Chaves² Servicio MeÂdico del Centro Penitenciario Madri... more ... JIF MartõÂn, Fernando Dronda,* and F. Chaves² Servicio MeÂdico del Centro Penitenciario Madrid-2, C/San Isidro,6; 38D, 28807, Alcala de Henares, Madrid, Spain, *Hospital RamoÂn y Cajal de Madrid, Spain, and ²Hospital 12 de Octubre de ... 3 Katz SI, Gallin JI, Hertz KC et al ...
Staphylococcus aureus is the main causal agent of infectious endocarditis (IE) in intravenous dru... more Staphylococcus aureus is the main causal agent of infectious endocarditis (IE) in intravenous drug addicts (IVDA) with most of the strains, isolated in Spain being resistant to penicillin and sensitive to methycillin, although the latter condition varied in recent years. Two cases of IE caused by S. aureus strains sensitive to penicillin in IVDA are presented. All bacteremia episodes diagnosed in the Hospital General Penitenciario (Madrid) over a 33-month period (March 1991 to December 1993) were prospectively studied. Special attention was given to patients diagnosed of IE. Blood cultures were processed according to the usual technique by a non radiometric system. One hundred and four bacteremias were detected with 14 being produced by S. aureus. Ten episodes of the total number of bacteremias fulfilled criteria for IE with 2 being produced by strains of S. aureus sensitive to penicillin (CMI < 0.06 mu/ml). Both patients had coinfection by HIV. The clinical evolution prior to diagnosis was prolonged although clinical and microbiologic cure were achieved with intravenous beta-lactam antibiotics treatment, without complications. Despite the low incidence of the isolation of Staphylococcus aureus sensitive to penicillin (< 3%) recently observed in Spain, strains producing severe infections, showing patterns of sensitivity such as those found during the preantibiotic era, may still be isolated.
To investigate the diversity of IS6110 fingerprints of Mycobacterium tuberculosis isolates in the... more To investigate the diversity of IS6110 fingerprints of Mycobacterium tuberculosis isolates in the United States and to determine if matching IS6110 fingerprints represent recent interstate tuberculosis transmission, we performed restriction fragment length polymorphism analysis of M. tuberculosis isolates from 1,326 patients in three geographically separated states. Seven hundred ninety-five different IS6110 fingerprint patterns were generated, and pattern diversity was similar in each state. Ninety-six percent of the fingerprint patterns were observed in only one state, demonstrating that most IS6110 fingerprint patterns are confined to a single geographic location. Of the IS6110 fingerprint patterns that were shared by isolates from more than one state, most isolates with 1 to 5 IS6110 copies were separable by pTBN12 fingerprinting whereas those with >15 copies were not. One high-copy-number M. tuberculosis strain had identical IS6110 and pTBN12 fingerprints and included 57 isolates from three states. Epidemiological data demonstrated significant recent transmission of tuberculosis within each city but not among the states. This suggests that identical fingerprints of isolates from geographically separate locations most likely reflect interstate tuberculosis transmission in the past, with subsequent intrastate spread of disease. Further evaluation of M. tuberculosis strains that cause outbreaks in different geographic locations will provide insight into the epidemiological and bacteriological factors that facilitate the spread of tuberculosis.
A comparison was made between DNA fingerprints of Mycobacterium tuberculosis produced with the in... more A comparison was made between DNA fingerprints of Mycobacterium tuberculosis produced with the insertion sequence IS6110 and those produced with the polymorphic GC-rich repetitive sequence contained in the plasmid pTBN12. A total of 302 M. tuberculosis isolates from the prison system in Madrid, Spain, and the Denver Public Health Department (Denver, Colo.) were analyzed with the two probes. Both probes identified the same isolates in the same clusters when the fingerprints had six or more copies of IS6110. Analysis of isolates with unique IS6110 fingerprints demonstrated that they were unique with pTBN12. The pTBN12 probe had greater discriminating power in isolates having five or fewer copies of IS6110. Forty-seven isolates from Denver having fewer than five copies of IS6110 which were grouped in 11 clusters with identical fingerprint patterns were subdivided into 35 different patterns by pTBN12. Isolates with IS6110 fingerprints with more than six copies of IS6110 that differed fr...
We report the complete genome sequence of Acinetobacter baumannii strain AbH12O-A2, isolated duri... more We report the complete genome sequence of Acinetobacter baumannii strain AbH12O-A2, isolated during a large outbreak in Spain. The genome has 3,875,775 bp and 3,526 coding sequences, with 39.4% G؉C content. The availability of this genome will facilitate the study of the pathogenicity of the Acinetobacter species.
Genetic alterations in the rpoB gene were characterized in 50 rifampin-resistant (Rif r ) clinica... more Genetic alterations in the rpoB gene were characterized in 50 rifampin-resistant (Rif r ) clinical isolates of Mycobacterium tuberculosis complex from Spain. A rapid PCR-enzyme-linked immunosorbent assay (ELISA) technique for the identification of rpoB mutations was evaluated with isolates of the M. tuberculosis complex and clinical specimens from tuberculosis patients that were positive for acid-fast bacilli (AFB). Sequence analysis demonstrated 11 different rpoB mutations among the Rif r isolates in the study. The most frequent mutations were those associated with codon 531 (24 of 50; 48%) and codon 526 (11 of 50; 22%). Although the PCR-ELISA does not permit characterization of the specific Rif r allele within each strain, 10 of the 11 Rif r genotypes were correctly identified by this method. We used the PCR-ELISA to predict the rifampin susceptibility of M. tuberculosis complex organisms from 30 AFB-positive sputum specimens. For 28 samples, of which 9 contained Rif r organisms and 19 contained susceptible strains, results were concordant with those based on culturebased drug susceptibility testing and sequencing. Results from the remaining two samples could not be interpreted because of low bacillary load (microscopy score of 1؉ for 1 to 9 microorganisms/100 fields). Our results suggest that the PCR-ELISA is an easy technique to implement and could be used as a rapid procedure for detecting rifampin resistance to complement conventional culture-based methods.
... Marıa Soledad Cuétara,1 Almudena Alhambra,2 Fernando Chaves,2 Marıa Dolores Moragues,3 José P... more ... Marıa Soledad Cuétara,1 Almudena Alhambra,2 Fernando Chaves,2 Marıa Dolores Moragues,3 José Pontón,4 and Amalia del Palacio2 1Servicios de Microbiologıa, Hospital Severo Ochoa, and 2Hospital ... Washington, DC: American Society for Microbiology, 2006:425. ...
The resistance of Acinetobacter baumannii strains to carbapenems is a worrying problem in hospita... more The resistance of Acinetobacter baumannii strains to carbapenems is a worrying problem in hospital settings. The main mechanism of carbapenem resistance is the expression of β-lactamases (metalloenzymes or class D enzymes). The mechanisms of the dissemination of these genes among A. baumannii strains are not fully understood. In this study we used two carbapenem-resistant clinical strains of A. baumannii (AbH12O-A2 and AbH12O-CU3) expressing the plasmid-borne bla(OXA-24) gene (plasmids pMMA2 and pMMCU3, respectively) to demonstrate that A. baumannii releases outer membrane vesicles (OMVs) during in vitro growth. The use of hybridization studies enabled us to show that these OMVs harbored the bla(OXA-24) gene. The incubation of these OMVs with the carbapenem-susceptible A. baumannii ATCC 17978 host strain yielded full resistance to carbapenems. The presence of the original plasmids harboring the bla(OXA-24) gene was detected in strain ATCC 17978 after the transformation of OMVs. New OMVs harboring bla(OXA-24) were released by A. baumannii ATCC 17978 after it was transformed with the original OMV-mediated plasmids, indicating the universality of the process. We present the first experimental evidence that clinical isolates of A. baumannii may release OMVs as a mechanism of horizontal gene transfer whereby carbapenem resistance genes are delivered to surrounding A. baumannii bacterial isolates.
Toxicon : official journal of the International Society on Toxinology, 1981
Neutralization of lethality, myonecrosis, hemorrhage and edema induced by Bothrops asper venom in... more Neutralization of lethality, myonecrosis, hemorrhage and edema induced by Bothrops asper venom in mice was studied using the polyvalent antivenom produced in the Instituto Clodomiro Picado. The neutralizing effect (ED50) on each of these toxic activities varied; the neutralization of lethal and hemorrhagic effects being more effective than the neutralization of myonecrosis and edema. With independent inoculation of venom and antivenom, antivenom was not effective in neutralizing edema-forming activity. The myonecrotic effect was only partially neutralized when serum was given i.v. immediately after envenomation; however, antivenin effectively neutralized the hemorrhagic activity. The ineffectiveness of antivenom in neutralizing edema and myonecrosis could be partially explained by the rapid development of these effects. Hence, the time interval between envenomation and antivenom administration and the route of serum administration both play an important role in the neutralization of...
The American journal of tropical medicine and hygiene
The effectiveness of the chelating agent CaNa2EDTA and the peptidomimetic matrix metalloproteinas... more The effectiveness of the chelating agent CaNa2EDTA and the peptidomimetic matrix metalloproteinase inhibitor batimastat (BB-94) to inhibit local tissue damage induced by Bothrops asper snake venom was studied in mice. Both compounds totally inhibited proteolytic, hemorrhagic, and dermonecrotic effects, and partially reduced edema-forming activity, when incubated with venom prior to injection. Much lower concentrations of batimastat than of CaNa2EDTA were required to inhibit these effects. In addition, batimastat, but not CaNa2EDTA, partially reduced myotoxic activity of the venom. When the inhibitors were administered at various time intervals after envenomation at the same site of venom injection, both compounds were effective in neutralizing local hemorrhage and dermonecrosis if administered rapidly after venom. Inhibition was not as effective as the time lapse between venom and inhibitor injections increased. Owing to the relevance of metalloproteinases in the pathogenesis of loc...
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Papers by F. Chaves