Detection and expression of SapS, a class C nonspecific acid phosphatase with O-phospho-L- tyrosine-phosphatase activity, in Staphylococcus aureus isolates from patients with chronic osteomyelitis / Detección y expresión de SapS, una fosfatasa ácida no específica de clase C con actividad de fosfatasa O-fosfotirosina, en aislamientos de Staphylococcus aureus de pacientes con osteomielitis crónica

Introduction. The identity of Staphylococcus aureus virulence factors involved in chronic osteomyelitis remains unresolved. SapS is a class C non-specific acid phosphatase and a well-known virulence factor that has been identified in S. aureus strain 154 but in protein extracts from rotting vegetables. Objective. To identify the SapS gene and characterize the activity of SapS from S. aureus strains: 12 isolates from bone infected samples of patients treated for chronic osteomyelitis and 49 from a database with in silico analysis of complete bacterial genomes. Materials and methods. The SapS gene was isolated and sequenced from 12 S. aureus clinical isolates and two reference strains; 49 S. aureus strains and 11 coagulase-negative staphylococci were tested using in silico PCR. Culture media semi-purified protein extracts from the clinical strains were assayed for phosphatase activity with p-nitro-phenyl- phosphate, O-phospho-L-tyrosine, O-phospho-L-serine, and OphosphoL-threonine in conjunction with various phosphatase inhibitors. Results. SapS was detected in the clinical and in-silico S. aureus strains, but not in the in silico coagulase-negative staphylococci strains. Sec-type I lipoprotein-type N-terminal signal peptide sequences; secreted proteins, and aspartate bipartite catalytic domains coding sequences were found in the SapS nucleotide and amino acid sequence analysis. SapS dephosphorylated with p-nitro-phenyl-phosphate and ophosphoLtyrosine were selectively resistant to tartrate and fluoride, but sensitive to vanadate and molybdate. Conclusion. SapS gene was found in the genome of the clinical isolates and the in silico S. aureus strains. SapS shares biochemical similarities with known virulent bacterial, such as protein tyrosine phosphatases, suggesting it may be a virulence factor in chronic osteomyelitis.

Introducción. Se desconoce la identidad de los factores de virulencia de Staphylococcus aureus implicados en la osteomielitis crónica. Sin embargo, SapS, una fosfatasa ácida no específica de clase C, es un factor de virulencia reconocido y ya fue identificada en la cepa 154 de S. aureus, pero en extractos proteicos de vegetales podridos. Objetivo. Detectar el gen SapS y caracterizar la actividad de la fosfatasa SapS en cepas de S. aureus aisladas de pacientes con osteomielitis crónica y en las reportadas en una base de datos de análisis in silico de genomas bacterianos completos. Materiales y métodos. Se aisló y secuenció el gen SapS en los 12 aislamientos clínicos de S. aureus y en dos cepas de referencia; estas secuencias se analizaron junto con las secuencias de las cepas reportadas en la base de datos de genomas bacterianos: 49 cepas de S. aureus y 11 cepas de estafilococos negativos para coagulasa. Se evalúo la actividad de la fosfatasa SapS, presente en los extractos de los sobrenadantes de los cultivos de las cepas clínicas, mediante la hidrólisis de fosfato p-nitrofenil, O-fosfo-L- tirosina, O-fosfo-L serina y O-fosfo-L treonina junto con varios inhibidores de fosfatasas. Resultados. Se detectó el gen SapS en el genoma de las cepas clínicas y en las 49 cepas de S. aureus analizadas in silico, pero no en las 11 cepas de estafilococos negativos para coagulasa. La secuenciación de SapS reveló un péptido señal presente en el extremo N-terminal de proteínas extracelulares y los dominios bipartitos de aspartato (DDDD) en su sitio catalítico. SapS hidroliza selectivamente el fosfato p-nitrofenil y la O-fosfo-L-tirosina, pero es sensible a vanadato y molibdato. Conclusión. Se encontró SapS en el genoma de S. aureus de las cepas clínicas y de las cepas de simulación computacional. La SapS con actividad específica para la hidrólisis de la O-fosfo-L-tirosina comparte similitudes bioquímicas con las fosfatasas-tirosina bacterianas, por lo que puede formar parte de la red de factores de virulencia de la osteomielitis crónica.

NK Cell Subpopulation Is Altered and the Expression of TLR1 and TLR9 Is Decreased in Patients with Acute Lymphoblastic Leukemia.

NK cells represent a heterogeneous subpopulation of lymphocytes of the innate immune system, which possess powerful antitumor activity. NK cells exhibit their function through a complex collection of receptors that act synergistically to recognize, regulate, or amplify the immune response. TLRs allow cells to detect PAMPs, MAMPs, or DAMPs, which are essential for the initiation of the immune response. Studies on the different subpopulations of NK cells and their expression profile of innate immune receptors in hematological cancers are limited. In this study, the specific subpopulations of NK cells in pediatric patients with acute lymphoblastic leukemia (ALL) and the repertoire and level of expression of TLRs in cytotoxic NK cells were assessed. The results suggested that pediatric patients with ALL exhibited a significant decrease in NK cells in peripheral blood and bone marrow, in addition to alterations in the distribution of the subpopulations of cells. Regulatory and cytotoxic NK cells were diminished, whereas dysfunctional phenotype was considerably increased. Cytotoxic NK cells from children with ALL expressed all 10 TLRs, and expression of TLR1 and TLR9 was decreased compared with the controls. Interestingly, cytotoxic NK cells exhibited a higher expression of TLR1 in the bone marrow than in the peripheral blood of patients with ALL. The present study is the first to show that TLR10 was expressed in the cytotoxic NK cells and the first to assess the profile and levels of the 10 known TLRs in cytotoxic NK cells from patients with ALL. The alterations in expression levels and cellular distribution may be involved in the immune response.

Antimicrobial resistance. Its importance and efforts to control it.

The World Health Organization estimates that bacterial resistance will cause 10 million deaths by 2050. As part of the Global Action Plan on Antimicrobial Resistance, it proposed networks of specialized laboratories in order to preserve strains and optimize the use of antimicrobials. That is the case of the Latin American Surveillance Network of Antimicrobials Resistance. In a 2019 study, the main bacteria of the ESKAPE group (which are highly resistant to the most widely used antibiotics) that cause infections in Mexican Hospitals were identified to be multidrug-resistant (MDR) and extended-spectrum beta-lactamase (ESBL)-producing Klebsiella spp., ESBL-producing Enterobacter spp., Acinetobacter baumannii, MDR Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium. With information on drug resistance, regimens are recommended to treat infection caused by Helicobacter pylori, a pathogen related to the development of cancer and whose prevalence in the adult population of Latin America is estimated to range between 60 and 70 %.

La Organización Mundial de la Salud estima que en 2050 la resistencia bacteriana ocasionará 10 millones de muertes. Como parte del Plan de Acción Mundial sobre la Resistencia a los Antimicrobianos propuso redes de laboratorios especializados, para conservar cepas y optimizar el uso de los antimicrobianos. En un estudio de 2019 se identificó que las principales bacterias del grupo ESKAPE (con alta resistencia a los antibióticos más usados) que causan infecciones en hospitales de México son Klebsiella spp. resistentes a múltiples fármacos (MDR) y productoras de betalactamasa de espectro extendido (BLEE), Enterobacter spp. BLEE, Acinetobacter baumannii, Pseudomonas aeruginosa MDR, Staphylococcus aureus meticilinorresistente y Enterococcus faecium resistente a vancomicina. Con la información de resistencia a los fármacos se recomiendan esquemas para tratar la infección causada por Helicobacter pylori, relacionado con el desarrollo de cáncer y cuya prevalencia en la población adulta de Latinoamérica se estima es de entre 60 y 70 %.

Resistencia antimicrobiana. Importancia y esfuerzos por contenerla / Antimicrobial resistance. Its importance and efforts to control it

Resumen La Organización Mundial de la Salud estima que en 2050 la resistencia bacteriana ocasionará 10 millones de muertes. Como parte del Plan de Acción Mundial sobre la Resistencia a los Antimicrobianos propuso redes de laboratorios especializados, para conservar cepas y optimizar el uso de los antimicrobianos. En un estudio de 2019 se identificó que las principales bacterias del grupo ESKAPE (con alta resistencia a los antibióticos más usados) que causan infecciones en hospitales de México son Klebsiella spp. resistentes a múltiples fármacos (MDR) y productoras de betalactamasa de espectro extendido (BLEE), Enterobacter spp. BLEE, Acinetobacter baumannii, Pseudomonas aeruginosa MDR, Staphylococcus aureus meticilinorresistente y Enterococcus faecium resistente a vancomicina. Con la información de resistencia a los fármacos se recomiendan esquemas para tratar la infección causada por Helicobacter pylori, relacionado con el desarrollo de cáncer y cuya prevalencia en la población adulta de Latinoamérica se estima es de entre 60 y 70 %.

Abstract The World Health Organization estimates that bacterial resistance will cause 10 million deaths by 2050. As part of the Global Action Plan on Antimicrobial Resistance, it proposed networks of specialized laboratories in order to preserve strains and optimize the use of antimicrobials. In a 2019 study, the main bacteria of the ESKAPE group (which are highly-resistant to the most widely used antibiotics) that cause infections in Mexican hospitals were identified to be multidrug-resistant (MDR) and extended spectrum beta-lactamase (ESBL)-producing Klebsiella spp., ESBL-producing Enterobacter spp., Acinetobacter baumannii, MDR Pseudomonas aeruginosa, methicillin-resistant Staphylococcus aureus and vancomycin-resistant Enterococcus faecium. With information on drug resistance, regimens are recommended to treat infection caused by Helicobacter pylori, a pathogen related to the development of cancer and whose prevalence in the adult population of Latin America is estimated to range between 60 and 70%.

Circulating blood levels of IL-6, IFN-γ, and IL-10 as potential diagnostic biomarkers in gastric cancer: a controlled study.

BACKGROUND: Gastric adenocarcinoma is the third most common cause of cancer-associated death worldwide. Helicobacter pylori infection activates a signaling cascade that induces production of cytokines and chemokines involved in the chronic inflammatory response that drives carcinogenesis. We evaluated circulating cytokines and chemokines as potential diagnostic biomarkers for gastric cancer. METHODS: We included 201 healthy controls and 162 patients with distal gastric cancer who underwent primary surgical resection between 2009 and 2012 in Mexico City. The clinical and pathological data of patients were recorded by questionnaire, and the cancer subtype was classified as intestinal or diffuse. Pathological staging of cancer was based on the tumor-node-metastasis staging system of the International Union Against Cancer. Concentrations of IL-1ß, IL-6, TNF-α, IL-10, and MCP-1 in serum were measured using multiplex analyte profiling technology and concentrations of IL-8, IFN-γ, and TGF-ß in plasma were measured using enzyme-linked immunosorbent assay. RESULTS: Levels of IL-1ß, IL-6, IFN-γ, and IL-10 were significantly higher and that of MCP-1 was lower in gastric cancer patients compared with controls. No differences in IL-8 or TNF-α levels were observed between gastric cancer and controls. IFN-γ and IL-10 were significantly higher in both intestinal and diffuse gastric cancer, whereas IL-1ß and IL-6 were higher and TGF-ß lower only in intestinal gastric cancer; MCP-1 was lower only in diffuse gastric cancer. IFN-γ and IL-10 levels were significantly higher in early (I/II) and late stage (III/IV) gastric cancer; IL-1ß and IL-8 were higher and MCP-1 was lower only in late stage (IV) patients. Receiver-operating characteristic analysis showed that for diagnosis of GC, IL-6 had high specificity (0.97) and low sensitivity (0.39), IL-10 had moderate specificity (0.82) and low sensitivity (0.48), and IL-1ß and IFN-γ showed low specificity (0.43 and 0.53, respectively) and moderate sensitivity (0.76 and 0.71, respectively). CONCLUSIONS: Increased levels of IL-6, IFN-γ, and IL-10 might be useful as diagnostic biomarkers for GC; however, this needs to be confirmed with larger number of patients and with control groups other than blood donors, properly age paired. IL-1ß, IL-6, MCP-1, and TGF-ß differentiate intestinal from diffuse GC. IFN-γ and IL-10 might be useful for diagnosis of early stage GC, and IL-1ß, IL-8, and MCP-1 for late stages of the disease.

Decidualization Mediated by Steroid Hormones Modulates the Innate Immunity in Response to Group B Streptococcal Infection in vitro.

BACKGROUND: Decidual cells play a role in the modulation of the innate immune response to protect pregnancy against infection. Steroid hormones regulate the innate immune response in different tissues, and they are involved in several biological processes like decidualization. The aim of this study was to assess if steroid hormones modulate the innate immunity in endometrial stromal cells (ESCs) and decidual stromal cells (DSCs) in response to group B streptococcus (GBS) infection in vitro. METHODS: Primary cultures of ESC were differentiated into DSC using 36 nM estradiol + 300 nM progesterone, and both were infected with GBS overnight. Concentrations of pro- and anti-inflammatory mediators (interleukin [IL]-1ß, IL-6, tumor necrosis factor [TNF]-α, IL-10, and TGF-ß), chemokines (IL-8 and GCP-2), and human ß-defensins (HBD-1, HBD-2, and HBD-3) were measured in the culture supernatants. RESULTS: DSCs showed a significant increase in IL-6 (p < 0.05), TNF-α (p < 0.05), IL-10 (p < 0.01), and TGF-ß (p < 0.05) secretion after GBS infection, while these changes were not observed in infected ESCs. IL-8 and GCP-2 increased after GBS infection, regardless of decidualization. ß-Defensins 1-3 decreased (p < 0.05) in ESCs after GBS infection, and hormone decidualization preserved the secretion of these antimicrobial peptides. CONCLUSIONS: Decidualization mediated by steroid hormones balance the pro- and anti-inflammatory response at the maternal-fetal interface under infection conditions.

Haemophilus influenzae triggers autophagy in HEp-2 cells.

The MAP-LC3 system regulates the intracellular formation of autophagy-associated vacuoles. These vacuoles contain the LC3 protein; thus it has been utilized as a marker to identify autophagosomes. The aim of our study was to investigate whether Haemophilus influenzae strains and their supernatants could activate autophagy in human larynx carcinoma cell line (HEp-2). We demonstrate that higher expression of the LC3B-II protein was induced, particularly by nontypeable Haemophilus influenzae (NTHi) 49766 and by supernatants, containing <50 kDa proteins, of both strains. Ultrastructural studies demonstrate vacuoles with a double membrane and/or membrane material inside, showing similar features to those of autophagic vacuoles. Together, our findings demonstrate that H. influenzae strains and their supernatants trigger an autophagic process.

Impact of cagPAI and T4SS on the inflammatory response of human neutrophils to Helicobacter pylori infection.

Helicobacter pylori contains a pathogenicity island, cagPAI, with genes homologous to components of the type IV secretion system (T4SS) of Agrobacterium tumefaciens. The T4SS components assemble a structure that transfers CagA protein and peptidoglycan into host epithelial cells, causing the increased release of interleukin 8 (IL8) from the cells. The Toll-like receptors on neutrophils recognize H. pylori, initiating signaling pathways that enhance the activation of NF-κB. However, the roles of cagPAI and T4SS in the inflammatory response of neutrophils are unknown. We evaluated the participation of cagPAI and T4SS in the response of human neutrophils to H. pylori infection. Neutrophils were isolated from the blood of healthy donors and infected with H. pylori cagPAI(+), cagPAI(-), and cagPAI mutant strains virB4 (-) and virD4 (-). Whereas cagPAI(+) strain 26695 induced the greatest IL8 production, a proinflammatory response, cagPAI(-) strain 8822 induced the greatest IL10 production, an anti-inflammatory response. In contrast, the virB4 (-) and virD4 (-) mutant strains produced significantly more of the two proinflammatory cytokines IL1ß and tumor necrosis factor αthan the cagPAI(+) strain 26695. We observed that H. pylori downregulated the expression of TLRs 2 and 5 but upregulated TLR9 expression in a cagPAI and T4SS-independent manner. These results show for the first time that the response of human neutrophils to H. pylori may vary from a pro-inflammatory to an anti-inflammatory response, depending on cagPAI and the integrity of T4SS.

vacA genotypes of Helicobacter pylori in the oral cavity and stomach of patients with chronic gastritis and gastric ulcer.

INTRODUCTION: Helicobacter pylori adheres to various components of the human saliva. Therefore, the objective of this research was to simultaneously detect H. pylori in saliva and in gastric biopsy, and to determine the agreement between the vacA genotypes in both saliva and gastric biopsy. MATERIALS AND METHODS: A total of 162 patients with chronic gastritis and 34 with gastric ulcer were studied, and saliva and biopsy samples were collected from each patient. H. pylori DNA was detected by conventional PCR and nested PCR was used for vacA genotyping. RESULTS: In 24% of the patients (47/196) H. pylori DNA was found in saliva and in biopsy; 52.5% (103/196) were saliva(negative)/biopsy(positive) and 6.6% (13/196) were saliva(positive)/biopsy(negative). In either or both H. pylori vacAs1m1 or s1m2 genotypes were detected in saliva in 41.5% of the patients with chronic gastritis. Forty-seven percent had >1 genotype, and the s1m1/s1m2 combination was found in 36% of them. H. pylori vacAs1m1 and s1m2 were also found in the saliva and biopsy of patients with gastric ulcer. The genotypes found in saliva and biopsy of the same patient had 51.1% agreement. In 27.6% of the 47 patients saliva(positive)/biopsy(positive) two genotypes were found in saliva, and one or both in the stomach. CONCLUSIONS: The s1m1/s1m2 genotypes, alone or together, are found simultaneously in saliva and gastric biopsy of the same patient. These results suggest that H. pylori reaches the oral cavity by various ways, and that saliva can be the transmitting and re-infecting vector.

[Toll-like receptors, pathogenesis and immune response to Helicobacter pylori]. / Receptores tipo Toll, patogénesis y respuesta inmune a Helicobacter pylori.

Helicobacter pylori colonize the gastric epithelial, most infected people are asymptomatic, 10 to 20% develop atrophic gastritis, peptic ulcer and less than 3% gastric cancer. These diseases are determined by the relationship between virulence factors of bacteria, host factors such as, genetic predisposition, and immune response. The innate immune response mainly represented by Toll-like receptors and Nod-like receptors that recognize their specific ligands, activate transcription factors as NF-kB, AP-1, CREB-1, inducing production of inflammatory cytokines such as IL -8, IL-12, IL-6, IL-1ß, IL-18, TNF-α and IL-10. Chronic inflammation promotes gastric morphological changes, prevents apoptosis and allows angiogenesis generating neoplasic lesions and cancer. The aim of this review is to analyze the mechanisms proposed to date of the innate and adaptative immune response involved in H. pylori infection; remarking the mechanisms related in the elimination or persistence.

Receptores tipo Toll, patogénesis y respuesta inmune a Helicobacter pylori / Toll-like receptors, pathogenesis and immune response to Helicobacter pylori

Helicobacter pylori coloniza el epitelio gástrico y la mayoría de las personas infectadas es asintomática, de 10 al 20 por ciento desarrolla gastritis atrófica, úlcera péptica, y menos de 3 por ciento genera cáncer gástrico. Estas patologías están determinadas por la relación entre los factores de virulencia de la bacteria y los factores del hospedero como predisposición genética y respuesta inmune. La inmunidad innata, representada principalmente por los receptores tipo Toll y tipo Nod, reconocen a sus ligandos específicos y activan factores de transcripción como NF-kB, AP-1, CREB-1, induciendo la producción de citocinas inflamatorias como IL-8, IL-12, IL-6, IL-1β, IL-18 y TNF-α, e IL-10. La inflamación crónica favorece los cambios de morfología gástrica, evita la apoptosis y favorece la angiogénesis, ocasionando lesiones neoplásicas y cáncer. El objetivo de esta revisión es analizar los mecanismos propuestos a la fecha de la respuesta inmune innata y adaptativa, involucrados en la infección por H. pylori, y se puntualiza en los mecanismos de eliminación o persistencia de la infección.

Helicobacter pylori colonize the gastric epithelial, most infected people are asymptomatic, 10 to 20 percent develop atrophic gastritis, peptic ulcer and less than 3 percent gastric cancer. These diseases are determined by the relationship between virulence factors of bacteria, host factors such as, genetic predisposition, and immune response. The innate immune response mainly represented by Toll-like receptors and Nod-like receptors that recognize their specific ligands, activate transcription factors as NF-kB, AP-1, CREB-1, inducing production of inflammatory cytokines such as IL -8, IL-12, IL-6, IL-1β, IL-18, TNF-α and IL-10. Chronic inflammation promotes gastric morphological changes, prevents apoptosis and allows angiogenesis generating neoplasic lesions and cancer. The aim of this review is to analyze the mechanisms proposed to date of the innate and adaptative immune response involved in H. pylori infection; remarking the mechanisms related in the elimination or persistence.

Interaction between pathogenic bacteria and intrauterine leukocytes triggers alternative molecular signaling cascades leading to labor in women.

Increased risk of preterm labor has been linked to cervicovaginal infection with Ureaplasma urealyticum and group B streptococci. Although various experimental models have been developed to study the role of amniochorion infection in preterm labor, they typically exclude the initial interaction between intrauterine leukocytes (recruited from decidual vessels into the avascular fetal membranes) and infecting bacteria. In this work, we ascertained whether inflammatory molecules secreted by bacterium-activated intrauterine leukocytes stimulate the amniochorion production of mediators involved in human labor. Using a two-step process beginning with placental circulating leukocytes as a proxy for intrauterine leukocytes, we found that coincubation of amniochorion explants with plasma from placental whole blood preincubated with group B streptococci resulted in a significant increase in tumor necrosis factor alpha (TNF-α) and matrix metalloproteinase 9 (MMP-9) levels in tissue. Extensive changes in the connective tissue arrangement and a decrease in collagen content demonstrated the degradation of the extracellular matrix following this treatment. In contrast, plasma from blood preconditioned with U. urealyticum induced a highly significant secretion of interleukin-1ß (IL-1ß) and prostaglandin E(2) (PGE(2)) by the amniochorion without changes in the extracellular matrix organization or content. These data demonstrate that group B streptococci induce degradation of the amniochorion as a result of MMP-9 production, probably via TNF-α, whereas U. urealyticum stimulates the secretion of PGE(2), probably via IL-1ß, potentially stimulating myometrial contraction. Our study provides novel evidence that the immunological cells circulating within the uterine microenvironment respond differentially to an infectious agent, triggering alternative molecular signaling pathways leading to human labor.

Giardia lamblia: interleukin 6 and tumor necrosis factor-alpha release from mast cells induced through an Ig-independent pathway.

Giardia lamblia is a common cause of both acute and chronic diarrheal disease in humans worldwide. It has been shown that mast cells, IL-6 and TNF-alpha are substantially involved in the early control of G. lamblia infection in mice. However, no studies have yet been reported concerning the interaction between mast cell and Giardia, as well as the mast cells mediators generated in response to Giardia infection. In this study we demonstrated the direct activation of mast cells by G. lamblia live trophozoites or trophozoite-derived antigens followed by an increase in tryptase expression and a significant release of the preformed mediator histamine. In addition, parasite derived antigens increased TNF-alpha and de novo synthesized cytokine IL-6, at the mRNA and protein level. These results strongly suggest that mast cells might be an important source not only of IL-6 but also of TNF-alpha during Giardia infection, playing an important role in the outcome of the infection.

Resistencia a linezolid en Staphylococcus aureus resistente a meticilina y enterococos con elevada resistencia a aminoglucósidos en un hospital pediátrico de tercer nivel / Resistance to linezolid in methicillin-resistant Staphylococcus aureus and Enterococcus with high-level resistance to aminoglycosides in a third-level pediatric hospital

Introducción: El surgimiento de resistencia a oxazolidinonas en Staphylococcus aureus resistentes a meticilina (SAMR) y Enterococcus spp con elevada resistencia a aminoglucósidos (EERA), aún cuando no han sido expuestos al antibiótico, es una de las principales razones para el control en el uso clínico de estos antibióticos. Métodos: Se estudiaron 95 cepas de SAMR y EERA, las cuales fueron aisladas de enero 2003 a diciembre 2007 en el Hospital Infantil de México Federico Gómez; se identificaron por pruebas convencionales. Se evaluó la susceptibilidad a diversos antimicrobianos incluyendo linezolid de acuerdo al Instituto de Estándares Clínicos y de Laboratorio (CLSI). Se comprobó la elevada resistencia a aminoglucósidos al amplificar los genes aac(6')-le, aph(2")-la y ant(6') en enterococos y el tipo de cásete cromosomal estafilocócico mee (SCCmec) asociado a la resistencia a meticilina en S. aureus, por técnicas moleculares previamente descritas. Resultados: Todas las cepas de SAMR mostraron el SCCmec tipo II. El 100% de los enterococos con fenotipo EERA mostraron genes asociados con los niveles elevados de resistencia a aminoglucósidos. El 12% (6/50) de EERA presentó valores intermedios a linezolid (concentración inhibitoria mínima (CIM) de 4 μg/mL) y sólo una cepa fue resistente (CIM 128 μg/mL); un aislamiento fue resistente a vancomicina fenotipo y genotipo van A, pero sensible a linezolid. El 2.2% (1/45) de los SAMR fue resistente a linezolid (CIM 8 μg/mL). Conclusión: Linezolid es una opción terapéutica de gran valor clínico. Sin embargo, son necesarios monitoreos continuos para conocer el riesgo de surgimiento de cepas resistentes y establecer lineamientos en el uso apropiado del antibiótico.

Background: The emergence of resistance to the oxazolidinones by methicillin-resistant Staphylococcus aureus (MRSA) and high-level aminoglycoside-resistant (HLRA) Enterococcus spp not exposed is one of the main reasons for control of the clinical use of these antibiotics. Methods: We studied 95 strains of MRSA and HLAR, which were isolated from January 2003 to December 2007 at the Hospital Infantil de México Federico Gómez. The strains were identified by conventional tests. Antimicrobial susceptibility was evaluated for several antimicrobial agents including linezolid according to the Clinical and Laboratory Standards Institute (CLSI). The high resistance to aminoglycosides was tested by amplification of genes aac (6')-/e, aph (2")-and ant (6') in enterococci. Staphylococcal cassette chromosomal mec (SCCmec) associated with MRSA was identified by molecular techniques described previously. Results: All MRSA strains showed SCCmec type II, and 100% of enterococci strains with phenotype HLAR showed genes associated with high-level aminoglycoside resistance; 12% of HLAR enterococci strains showed intermediate values to linezolid (MIC 4 μg/mL) and only one strain was resistant (MIC 128 μg/mL). Of the MRSA strains, 2.2% were resistant to linezolid (MIC 8 μg/mL). Conclusion: Linezolid is a clinically valuable option as a form of therapy. However, continuous surveillance is necessary to determine the emergent risk of resistance strains and to establish guidelines for appropriate use.

Culture supernatants from V. cholerae O1 ElTor strains isolated from different geographic areas induce cell vacuolation and cytotoxicity / Cepas de V. cholerae O1 biotipo ElTor aisladas de diferente origen geográfico inducen vacuolización celular y citotoxicidad

OBJECTIVE: To investigate whether the HlyA-induced vacuolating effect is produced by V. cholerae O1 ElTor strains isolated from different geographic origins, including Mexico. MATERIAL AND METHODS: Supernatant-induced haemolysis, vacuolating activity and cytotoxicity in Vero cells were recorded. PCR, RFLP analysis and molecular cloning were performed. RESULTS: All ElTor strains analyzed induced cellular vacuolation. Ribotype 2 strains isolates from the U.S. gulf coast yielded the highest titer of vacuolating activity. Eight of nine strains were haemolytic, while all strains were PCR positive for the hlyA gene. We cloned the hlyA gene from two ElTor strains, a toxigenic (2514-88, ctxAB+) and a non-toxigenic Mexican strain (CM 91-3, ctxAB-). Supernatant from those recombinant E. coli strains induced haemolysis, cell vacuolation and cytotoxicity. RFLP-PCR analysis revealed similarities in the hlyA gene from all strains tested. CONCLUSION: The HlyA-induced vacuolating effect is a widespread phenotype of epidemic V. cholerae O1 ElTor strains.

OBJETIVO: Analizar el efecto vacuolizante de cepas de V. cholerae O1 ElTor aisladas de diferente origen geográfico, incluyendo México. MATERIAL Y MÉTODOS: Se realizaron pruebas de hemolisis, vacuolización y citotoxicidad en células Vero, así como PCR, análisis por RFLP y clonación molecular. RESULTADOS: Todas las cepas indujeron el efecto vacuolizante. Las cepas del ribotipo 2, aisladas de las costas del Golfo en Estados Unidos, presentaron títulos altos de vacuolización. El gen hlyA fue amplificado en las nueve cepas mediante PCR, aunque sólo ocho fueron hemolíticas. Se clonó el gen hlyA de una cepa toxigénica (2514-88, ctxAB+) y de una cepa no toxigénica aislada en México (CM 91-3, ctxAB-). El sobrenadante de las clonas recombinantes indujo hemólisis, efecto vacuolizante y citotoxicidad. El RFLP mostró alta similitud del gen hlyA de las cepas estudiadas. CONCLUSIÓN: El efecto vacuolizante es un fenotipo ampliamente distribuido en cepas epidémicas de V. cholerae O1 biotipo ElTor.

Interacción sinérgica entre Mycoplasma fermentans y la exposición a ceniza volcánica / Synergistic interaction between Mycoplasma fermentans and exposure to volcanic ash

Introducción: Mycoplasma fermentans presenta propiedades inmunorreguladoras y puede desencadenar infecciones crónicas con signos leves de la enfermedad. Por su parte, la materia partículada atmosférica es un componente diverso y complejo de la contaminación del aire y que se asocia a efectos adversos para la salud. Objetivo: Estudiar el daño producido por la inoculación de Mycoplasma fermentans y la exposición a ceniza volcánica. Materiales y métodos: Las muestras de ceniza se colectaron en zonas cercanas al volcán Popocatépetl. Diez hamsters se expusieron a la inhalación de ceniza volcánica, tros diez ejemplares fueron inoculados intratraquealmente con Mycoplasma fermentans y expuestos a inhalación de ceniza volcánica. Diez hamsters no fueron inoculados ni expuestos a la inhalación de ceniza, considerándose como grupo control. A partir del día 60 los ejemplares se sacrificaron, obteniéndose muestras de sangre para determinar el hematocrito, la cuenta diferencial y detección de anticuerpos. Se realizó estudio histopatológico al tejido pulmonar de los ejemplares. Resultados: El grupo de hamsters expuestos a la ceniza volcánica mostraron perdida en peso y decremento en el conteo de neutrófilos. No se detectaron anticuerpos contra Mycoplasma fermentans. El tejido pulmonar de los ejemplares expuestos a la ceniza mostró detritus celulares, reacción inflamatoria aguda e infiltrado linfocitario. Los hamsters previamente infectados y expuestos a la ceniza volcánica presentaronengrosamiento de la pared alveolar, infiltrado de células plasmáticas, neutrófilos y foco hemorrágico. Estos resultados indican que Mycoplasma fermentans puede interaccionar con estímulos ambientales, como es el caso de la ceniza volcánica, pontecializando efectos adversos en la salud.

Serogroups, K1 antigen, and antimicrobial resistance patterns of Aeromonas spp. strains isolated from different sources in Mexico

A total of 221 strains of Aeromonas species isolated in Mexico from clinical (161), environmental (40), and food (20) samples were identified using the automated system bioMérieux-Vitek®. Antisera for serogroups O1 to 044 were tested using the Shimada and Sakazaki scheme. The K1 antigen was examined using as antiserum the O7:K1C of Escherichia coli. Besides, we studied the antimicrobial patterns according to Vitek AutoMicrobic system. Among the 161 clinical strains 60 percent were identified as A. hydrophila, 20.4 percent as A. caviae, and 19.25 percent as A. veronii biovar sobria. Only A. hydrophila and A. veronii biovar sobria were found in food (55 and 90 percent respectively) and environmental sources (45 and 10 percent respectively). Using "O" antisera, only 42.5 percent (94/221) of the strains were serologically identified, 55 percent (121/221) were non-typable, and 2.5 percent (6/221) were rough strains. Twenty-two different serogroups were found, O14, O16, O19, O22, and O34 represented 60 percent of the serotyped strains. More than 50 percent of Aeromonas strain examined (112/221) expressed K1 encapsulating antigen; this characteristic was predominant among Aeromonas strains of clinical origin. Resistance to ampicillin/sulbactam and cephazolin was detected in 100 and 67 percent of Aeromonas strain tested for their susceptibility to antibiotics. In conclusion, antibiotic-resistant Aeromonas species that possess the K1 encapsulating antigen and represent serogroups associated with clinical syndrome in man are not uncommon among Aeromonas strains isolated from clinical, food and environmental sources in Mexico.

Papel del laboratorio clínico ante el bioterrorismo / The role of the clinical laboratory facing bioterrorism

Con el creciente reto de que los agentes biológicos se utilicen afectando a toda la población, el impacto para los laboratorios clínicos es más directo. Si ocurriera un evento bioterrorista el laboratorio clínico promedio podría ser fundamental para ayudar a detectar e identificar al agente biológico utilizado y alertar a las autoridades. Aunque Bacillus anthracis y el virus de la viruela han recibido la mayor publicidad como agentes de guerra biológica, el término de agente biológico se aplica a un diverso grupo de microorganismos, así como a toxinas, plantas y animales.Esta revisión traza los orígenes de los agentes de guerra biológica y describe la percepción actual del reto que suponen tales agentes, el papel que podrían jugar los laboratorios clínicos, y los aspectos clínicos y microbiológicos de los agentes que tienen las mayores posibilidades de ser utilizados con este propósito.

Ántrax. Microbiología epidemiología, manifestaciones clínicas, diagnóstico, prevención y tratamiento / Anthrax. Microbiology, epidemiology, clinical manifestions, diagnosis, prevention and treatment

Por siglos, el ántrax ha sido causa de enfermedad en animales y menos frecuente en humanos; la investigación del ántrax como arma biológica comenzó a realizarse hace más de 80 años. De los numerosos agentes biológicos que pueden ser utilizados como armas el ántrax es uno de los más importantes. En 1970 un Comité de Expertos de la Organización Mundial de la Salud estimó que el número de casos después de la liberación de 50 kg de esporas de ántrax por vía aérea sobre una ciudad de 500,000 habitantes sería de 125,000, de los cuales 95,000 morirían si no se les administrara tratamiento oportuno.Para responder de manera efectiva a un ataque terrorista con ántrax la comunidad médica requiere del conocimiento acerca de la genética, patogénesis, prevención y tratamiento de tal enfermedad, además del apoyo de un laboratorio clínico; si el laboratorio es alertado sobre la posibilidad de ántrax, las tinciones de gram, las pruebas bioquímicas y las características tintorales del organismo pueden proporcionar un diagnóstico preliminar 12 a 24 horas después.Un diagnóstico definitivo puede requerir de 1 o 2 días adicionales de pruebas en un laboratorio de referencia. En esta revisión se analizarán la microbiología, patogénesis, manifestaciones clínicas, epidemiología, diagnóstico prevención y tratamiento del ántrax.