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Mexico City, Mexico

Ortiz-Benitez E.A.,National Autonomous University of Mexico | Carrillo-Morales M.,National Autonomous University of Mexico | Velazquez-Guadarrama N.,Laboratorio Of Infectologia | Fandino-Armas J.,National Autonomous University of Mexico | De Jesus Olivares-Trejo J.,National Autonomous University of Mexico

Streptococcus pneumoniae is a human pathogen whose principal virulence factor is its capsule. This structure allows the bacterium to evade the human immune system. Treatment of infections caused by this bacterium is based on antibiotics; however, the emergence of antibiotic-resistant strains makes this task increasingly difficult. Therefore, it is necessary to investigate new therapies, such as those based on gold nanoparticles, for which unfortunately the mechanisms involved have not yet been investigated. As far as we know, this study is the first that attempts to explain how gold nanoparticles destroy the bacterium Streptococcus pneumoniae. We found that the mean particle size was an important issue, and that the effect on the bacterium was dose-dependent. Cellular growth was inhibited by the presence of the nanoparticles, as was cell viability. The pH of the bacterial growth media was acidified, but interestingly the reactive species were not affected. A transmission electron microscopy analysis revealed the presence of inclusion bodies of gold nanoparticles within the bacterium. We present the first findings that attempt to explain how gold nanoparticles lyse Gram-positive bacteria. This journal is © The Royal Society of Chemistry. Source

Cazares-Dominguez V.,Laboratorio Of Investigacion En Bacteriologia Intestinal | Ochoa S.A.,Laboratorio Of Investigacion En Bacteriologia Intestinal | Cruz-Cordova A.,Laboratorio Of Investigacion En Bacteriologia Intestinal | Rodea G.E.,Laboratorio Of Investigacion En Bacteriologia Intestinal | And 5 more authors.
Frontiers in Microbiology

Staphylococcus aureus is an opportunistic pathogen that colonizes human hosts and causes a wide variety of diseases. Two interacting regulatory systems called agr (accessory gene regulator) and sar (staphylococcal accessory regulator) are involved in the regulation of virulence factors. The aim of this study was to evaluate the effect of vancomycin on hld and spa gene expression during the exponential and post-exponential growth phases in multidrug-resistant (MDR) S. aureus. Methods: Antibiotic susceptibility was evaluated by the standard microdilution method. The phylogenetic profile was obtained by pulsed-field gel electrophoresis (PFGE). Polymorphisms of agr and SCCmec (staphylococcal cassette chromosome mec) were analyzed by multiplex polymerase chain reaction (PCR). The expression levels of hld and spa were analyzed by reverse transcription-PCR. An enzyme-linked immunosorbent assay (ELISA) was performed to detect protein A, and biofilm formation was analyzed via crystal violet staining. Results: In total, 60.60% (20/33) of S. aureus clinical isolates were MDR. Half (10/20) of the MDR S. aureus isolates were distributed in subcluster 10, with >90% similarity among them. In the isolates of this subcluster, a high prevalence (100%) for the agrII and the cassette SCCmec II polymorphisms was found. Our data showed significant increases in hld expression during the post-exponential phase in the presence and absence of vancomycin. Significant increases in spa expression, protein A production and biofilm formation were observed during the post-exponential phase when the MDR S. aureus isolates were challenged with vancomycin. Conclusion: The polymorphism agrII, which is associated with nosocomial isolates, was the most prevalent polymorphism in MDR S. aureus. Additionally, under our study conditions, vancomycin modified hld and spa expression in these clinical isolates. Therefore, vancomycin may regulate alternative systems that jointly participate in the regulation of these virulence factors. © 2015 Cázares-Domínguez, Ochoa, Cruz-Córdova, Rodea, Escalona, Olivares, Olivares-Trejo, Velázquez-Guadarrama and Xicohtencatl-Cortes. Source

Mendoza-Elizalde S.,Laboratorio Of Infectologia | Mendoza-Elizalde S.,National Polytechnic Institute of Mexico | Cortes-Marquez A.C.,Laboratorio Of Infectologia | Cortes-Marquez A.C.,National Polytechnic Institute of Mexico | And 8 more authors.
Infection, Genetics and Evolution

Genotypic differences in Helicobacter pylori play an important role in infection. We characterized the diversity of the cagA, cagE, babA2, and vacA genes in H. pylori strains isolated from pediatric patients and the relationship between these genes and clinical disease. Additionally, we employed the Neighbor-net algorithm to predict the behavior of the genotypes of the strains isolated from patients. Of 93 patients analyzed, 32 were positive for infection. A total of 160 H. pylori strains (five isolates per positive patient) were analyzed. A total of 91% and 83% of strains possessed the cagA and cagE genes, respectively. For the vacA gene, 84% of strains possessed the s1 allele, 15% the s2 allele, 81% the m1 allele and 13.8% the m2 allele. The babA2 gene was present in 79% of strains. Infection with H. pylori strains with the vacA ( s1m1) genotype was associated with risk of esophagitis and gastritis ( p= 0.0001). The combination of cagA and vacA ( s1m1) was significantly associated with abdominal pain ( p= 0.002); however, EPIYA type was not significantly associated with abdominal pain. A total of 16 different genotypes were identified; the most common genotype was vacAs1m1cagA+. cagE+. babA2+ (47.5%). A total of 84% of pediatric patients were infected by at least two and up to five different genotypes. The network recovered two genotype groups (A: strains with vacAs1 and B: strains with vacAs2). The presence of multiple paths in the network suggests that reticulate events, such as recombination or reinfection, have contributed to the observed genotypic diversity. © 2014 Elsevier B.V. Source

Cruz-Cordova A.,Laboratorio Of Investigacion En Bacteriologia Intestinal | Espinosa-Mazariego K.,Laboratorio Of Investigacion En Bacteriologia Intestinal | Ochoa S.A.,Laboratorio Of Investigacion En Bacteriologia Intestinal | Saldana Z.,Laboratorio Of Investigacion En Bacteriologia Intestinal | And 13 more authors.
Frontiers in Microbiology

Background: Enterotoxigenic Escherichia coli (ETEC) colonize the human intestinal mucosa using pili and non-pili colonization factors (CFs). CS21 (also designated Longus) is one of the most prevalent CFs encoded by a 14 kb lng DNA cluster located in a virulence plasmid of ETEC; yet limited information is available on the prevalence of CS21 positive ETEC isolates in different countries. The aim of this study was to evaluate the prevalence of CS21 among ETEC clinical isolates from Mexican and Bangladeshi children under 5 years old with diarrhea and to determine the phenotypic and genotypic features of these isolates. Methods: ETEC clinical isolates positive to lngA gene were characterized by genotype, multidrug-resistance, self-aggregation, biofilm formation, and adherence to HT-29 cell line. Results: A collection of 303 E. coli clinical isolates were analyzed, the 81.51% (247/303) were identified as ETEC, 30.76% (76/247) were st+/lt+, and 25.10% (62/247) were positive for the lngA gene. Among the lngA+ ETECs identified, 50% of isolates (31/62) were positive for LngA protein. The most frequent serotype was O128ac:H12 found in 19.35% (12/62) of lngA+ ETEC studied. Multidrug-resistance (MDR) lngA+ ETEC isolates was identified in 65% (39/60), self-aggregation in 48.38% (30/62), and biofilm formation in 83.87% (52/62). ETEC lngA+ isolates were able to adhere to HT-29 cells at different levels. Two lngA isogenic mutants were constructed in the ETEC E9034A and ETEC73332 clinical isolate, showing a 77% and 98% reduction in adherence, respectively with respect to the wild type. Conclusion: ETEC isolates that have the lngA gene showed features associated with self-aggregation, and adherence to HT-29 cells, important characteristics in the human gut colonization process and pathogenesis. © 2014 2014 Cruz-Córdova, Espinosa-Mazariego, Ochoa, Saldaña, Rodea, Cázares-Domínguez, Rodríguez-Ramírez, Eslava-Campos, Navarro-Ocaña, Arrellano-Galindo, Hernández-Castro, Gómez-Duarte, Qadri and Xicohtencatl-Cortes. Source

Ochoa S.A.,Laboratorio Of Investigacion En Bacteriologia Intestinal | Cruz-Cordova A.,Laboratorio Of Investigacion En Bacteriologia Intestinal | Rodea G.E.,Laboratorio Of Investigacion En Bacteriologia Intestinal | Cazares-Dominguez V.,Laboratorio Of Investigacion En Bacteriologia Intestinal | And 5 more authors.
Microbiological Research

Background: Pseudomonas aeruginosa is an opportunistic pathogen that has acquired several mechanisms of resistance to multiple groups of antibiotic agents and has been widely employed as a model organism for the study of biofilm formation. Many P. aeruginosa structures embedded in the extracellular matrix, such as exopolysaccharides (EPS), flagella, and type-IV pili (T4P), have been associated with biofilm formation. In this study, we assess biofilm formation by crystal violet quantification in clinical strains of multidrug-resistant (MDR) P. aeruginosa isolated from the Hospital Infantil de México Federico Gómez (HIMFG) associated to total and reducing EPS production (quantification by the anthrone and DNS method, respectively), twitching motility activity by T4P, and flagellar-mediated motility. Results: The determination of Minimum Inhibitory Concentration (MIC) showed that >50% of P. aeruginosa strains were resistant to 12 different antibiotics (TIC, CAZ, CTX, CRO, FEP, AZT, GM, CIP, LEV, PZT, IMP, and MEM). Total and reducing EPS analysis of the 58 biofilm-forming MDR P. aeruginosa strains showed heterogeneous values ranging from OD600 9.06 to 212.33, displaying a linear correlation with the production of total EPS (59.66μg/ml to 6000.33μg/ml; R2=0.89), and a higher correlation with reducing EPS (88.33μg/ml to 1100.66μg/ml; R2=0.96). T4P twitching motility showed a moderated linear correlation (2.00mm to 28.33mm; R2=0.74). Even though it has been demonstrated that flagella contribute to the initial stages of biofilm formation, crystal violet analysis showed a moderate correlation (R2=0.49) with flagellar-mediated motility in MDR P. aeruginosa under the tested conditions. In addition, PFGE profiles revealed two subgroups generating profiles group A, consisting of 89.63% (52/58) of the strains, and group B, consisting of 13.09% (6/58) of the strains. Conclusions: Phenotypic analysis showed a correlation among the biofilms developed in the MDR P. aeruginosa strains with EPS (total and reducing) production, T4P-activity by twitching motility and flagellar-mediated motility. © 2014 Elsevier GmbH. Source

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