Association of virulence plasmid and antibiotic resistance determinants with chromosomal multilocus genotypes in Mexican Salmonella enterica serovar Typhimurium strains

<p>Abstract</p> <p>Background</p> <p>Bacterial genomes are mosaic structures composed of genes present in every strain of the same species (core genome), and genes present in some but not all strains of a species (accessory genome). The aim of this study was to compare the genetic diversity of core and accessory genes of a <it>Salmonella enterica </it>subspecies <it>enterica </it>serovar Typhimurium (Typhimurium) population isolated from food-animal and human sources in four regions of Mexico. Multilocus sequence typing (MLST) and macrorestriction fingerprints by pulsed-field gel electrophoresis (PFGE) were used to address the core genetic variation, and genes involved in pathogenesis and antibiotic resistance were selected to evaluate the accessory genome.</p> <p>Results</p> <p>We found a low genetic diversity for both housekeeping and accessory genes. Sequence type 19 (ST19) was supported as the founder genotype of STs 213, 302 and 429. We found a temporal pattern in which the derived ST213 is replacing the founder ST19 in the four geographic regions analyzed and a geographic trend in the number of resistance determinants. The distribution of the accessory genes was not random among chromosomal genotypes. We detected strong associations among the different accessory genes and the multilocus chromosomal genotypes (STs). First, the <it>Salmonella </it>virulence plasmid (pSTV) was found mostly in ST19 isolates. Second, the plasmid-borne betalactamase <it>cmy-2 </it>was found only in ST213 isolates. Third, the most abundant integron, IP-1 (<it>dfrA12</it>, <it>orfF </it>and <it>aadA2</it>), was found only in ST213 isolates. Fourth, the <it>Salmonella </it>genomic island (SGI1) was found mainly in a subgroup of ST19 isolates carrying pSTV. The mapping of accessory genes and multilocus genotypes on the dendrogram derived from macrorestiction fingerprints allowed the establishment of genetic subgroups within the population.</p> <p>Conclusion</p> <p>Despite the low levels of genetic diversity of core and accessory genes, the non-random distribution of the accessory genes across chromosomal backgrounds allowed us to discover genetic subgroups within the population. This study provides information about the importance of the accessory genome in generating genetic variability within a bacterial population.</p

Optic neuropathy and congenital glaucoma associated with probable Zika virus infection in Venezuelan patients

Introduction: Although the current Zika virus (ZIKV) epidemic is a major public health concern, most reports have focused on congenital ZIKV syndrome, its most devastating manifestation. Severe ocular complications associated with ZIKV infections and possible pathogenetic factors are rarely described. Here, we describe three Venezuelan patients who developed severe ocular manifestations following ZIKV infections. We also analyse their serological response to ZIKV and dengue virus (DENV). Case presentation: One adult with bilateral optic neuritis, a child of 4 years of age with retrobulbar neuritis [corrected]. and a newborn with bilateral congenital glaucoma had a recent history of an acute exanthematous infection consistent with ZIKV infection. The results of ELISA tests indicated that all patients were seropositive for ZIKV and four DENV serotypes. Conclusion: Patients with ZIKV infection can develop severe ocular complications. Anti-DENV antibodies from previous infections could play a role in the pathogenesis of these complications. Well-designed epidemiological studies are urgently needed to measure the risk of ZIKV ocular complications and confirm whether they are associated with the presence of anti-flaviviral antibodies

Non-congenital severe ocular complications of Zika virus infection

In 2016, during a major Zika virus (ZIKV) outbreak in Maracaibo, Venezuela, a 49-year-old woman and an unrelated 4-year-old boy developed bilateral optic neuritis 2–3 weeks after presenting an acute febrile illness characterized by low-grade fever, rash and myalgia [1]. Both patients presented sudden, painless bilateral loss of vision with no corneal or uveal abnormalities. Fundoscopic examination revealed oedema of the optic nerve and optic disc pallor. Optical coherence tomography confirmed bilateral optic nerve head swelling in the case of the adult, but it was not carried out in the child. Automated perimetry performed in the adult revealed bilateral diffuse visual field loss. Magnetic resonance imaging of the brain in both cases was unremarkable. Both patients were diagnosed with bilateral optic neuritis of possible infectious or parainfectious origin. Differential diagnoses that were considered and subsequently discarded included arteritic and non-arteritic ischaemic optic neuropathy, and brain disorders such as multiple sclerosis and brain tumours. Both patients were seropositive for anti-ZIKV IgG and seronegative for anti-ZIKV IgM. In addition, both patients were positive for anti-dengue virus (DENV) IgG for all four DENV serotypes. Management included intravenous methylprednisolone for 3 days, followed by oral prednisolone for 11 days. Although the patients presented a modest improvement in their vision, they continued to have visual impairment after several months of follow-up [1]

Epidemia de neumonía asociada a ventilación mecánica en Mérida, Yucatán

OBJETIVO. Determinar las principales características epidemiológicas, clínicas y microbiológicas de una epidemia de neumonía asociada a ventilación mecánica en una unidad de cuidados intensivos en Mérida, Yucatán. MATERIAL Y MÉTODOS. Se diseñó un estudio prospectivo y observacional de 11 meses para determinar incidencia, mortalidad, reservorios potenciales, agentes etiológicos y sus patrones de sensibilidad antimicrobiana. RESULTADOS. La incidencia de neumonía asociada a ventilador fue de 74%. La mortalidad cruda fue de 88%, comparada con una mortalidad esperada de 19.5%. Se aislaron bacterias gramnegativas en 98% de los cultivos, de las cuales 46% fueron sensibles a cefalosporinas de tercera generación, 59% a cefalosporinas de cuarta generación, 70% a ciprofloxacina y 100% a imipenem. Se aislaron Klebsiella pneumoniae y Pseudomonas aeruginosa de algunos circuitos del ventilador y el lavado. CONCLUSIONES. La elevada incidencia de neumonía y la mortalidad asociada en esta unidad de cuidados intensivos se pueden atribuir a la falta de medidas de control de infecciones y a una elevada prevalencia de gérmenes multirresistentes que se relaciona con el uso desmesurado e irracional de antibióticos

Epidemia de neumonía asociada a ventilación mecánica en Mérida, Yucatán An outbreak of ventilator-associated pneumonia in Merida, Yucatán

OBJETIVO. Determinar las principales características epidemiológicas, clínicas y microbiológicas de una epidemia de neumonía asociada a ventilación mecánica en una unidad de cuidados intensivos en Mérida, Yucatán. MATERIAL Y MÉTODOS. Se diseñó un estudio prospectivo y observacional de 11 meses para determinar incidencia, mortalidad, reservorios potenciales, agentes etiológicos y sus patrones de sensibilidad antimicrobiana. RESULTADOS. La incidencia de neumonía asociada a ventilador fue de 74%. La mortalidad cruda fue de 88%, comparada con una mortalidad esperada de 19.5%. Se aislaron bacterias gramnegativas en 98% de los cultivos, de las cuales 46% fueron sensibles a cefalosporinas de tercera generación, 59% a cefalosporinas de cuarta generación, 70% a ciprofloxacina y 100% a imipenem. Se aislaron Klebsiella pneumoniae y Pseudomonas aeruginosa de algunos circuitos del ventilador y el lavado. CONCLUSIONES. La elevada incidencia de neumonía y la mortalidad asociada en esta unidad de cuidados intensivos se pueden atribuir a la falta de medidas de control de infecciones y a una elevada prevalencia de gérmenes multirresistentes que se relaciona con el uso desmesurado e irracional de antibióticos.OBJECTIVES. To determine the main epidemiological, clinical, and microbiologic characteristics of an outbreak of ventilator-associated pneumonia at an intensive care unit in Yucatan. MATERIAL AND METHODS. An 11-month prospective and observational study was designed to determine incidence, mortality, potential reservoirs, etiologic agents and antibiotic susceptibility patterns. RESULTS. The incidence of ventilator-associated pneumonia was 74%. The crude mortality rate was 88% compared to a 19.5% expected-mortality rate. Gram-negative bacteria were isolated from 98% of the cultures, of which 46% were susceptible to third generation cephalosporins, 59% to fourth generation cephalosporins, 70% to ciprofloxacin and 100% to imipenem. Klebsiella pneumoniae and Pseudomonas aeruginosa were isolated from some of the ventilator circuits and the sink. CONCLUSIONS. The high incidence of pneumonia and associated mortality in our intensive care unit may be attributed to the absence of infection control measures and the high prevalence of multiresistant organisms which is related to antibiotic abuse

Incidence, clinical presentation, and antimicrobial resistance trends in Salmonella and Shigella infections from children in Yucatan, Mexico

Background: Salmonella and Shigella cause significant morbidity and mortality among children worldwide. Increased antimicrobial resistance results in greater burden of disease. Methods: From 2005 to 2011, Salmonella and Shigella isolates collected from ill children at a major hospital in Yucatan, Mexico, were subjected to serotyping and antimicrobial susceptibility testing by disk diffusion and agar dilution. The identification of blaCTX, blaCMY, blaSHV, blaTEM, and blaOXA and qnr resistance genes was conducted by PCR and sequencing. Results: Among 2344 children with acute gastroenteritis, salmonellosis decreased from 17.7% in 2005 to 11.2% in 2011 (p&lt;0.001). In contrast, shigellosis increased from 8.3% in 2010 to 12.1% in 2011. Compared to children with Salmonella, those with Shigella had significantly more bloody stools (59% vs 36%, p&lt;0.001), dehydration (27% vs 15%, p=0.031), and seizures (11% vs 3%, p=0.03). In Salmonella (n=365), there was a significant decrease in resistance to ampicillin (43% to 16%, p&lt;0.001), trimethoprim-sulfamethoxazole (44% to 26%, p=0.014), and extended-spectrum cephalosporins (27% to 10%, p=0.009). Reduced susceptibility to ciprofloxacin in Salmonella rose from 30% to 41% (p&lt;0.001). All ceftriaxone-resistant isolates harbored the blaCMY-2 gene. qnr genes were found in 42 (36%) of the 117 Salmonella isolates with a ciprofloxacin MIC ≥ 0.125 &#181;g/ml. Four were qnrA1 and 38 were qnrB19. Resistance to ampicillin (40%) and trimethoprim-sulfamethoxazole (58%) was common in Shigella (n=218), but isolates remained fully susceptible to ceftriaxone and ciprofloxacin. Conclusions:Illness from Salmonella has decreased while severe Shigella infections have increased among children with gastroenteritis in the Yucatan Peninsula. While Shigella resistance to clinically important antibiotics remained unchanged, resistance to most of these, except ciprofloxacin, declined in Salmonella. blaCMY-2 and qnr genes are common in Salmonella isolates

Prevalencia y factores de riesgo en Yucatán, México, para litiasis urinaria

Objetivo. Determinar la prevalencia de urolitiasis en el estado de Yucatán, México, y una posible asociación de ésta con antecedentes familiares de la enfermedad y la dureza del agua. Material y métodos. Durante 1996 se efectuó una encuesta transversal en población abierta mayor de un año de edad, del estado de Yucatán. Los sujetos se clasificaron como litiasis definitiva (LD), litiasis probable (LP) y sin litiasis (SL). Se determinó dureza total, dureza de calcio y dureza de magnesio a las muestras de agua empleadas para el consumo humano. Se emplearon ji cuadrada y t de student para comparación de medias de muestras independientes en el análisis. Resultados. De un total de 5 832 encuestas, 323 sujetos (5.5%) se catalogaron como LD, y 282 (4.8%) como LP. La prevalencia de litiasis se incrementó con la edad, partiendo de 1% en población de 18 años o menor, hasta 11.3% en los mayores de 50. El 44% del grupo LD y 34% del LP tuvieron antecedente familiar de urolitiasis, comparado con 28% del grupo SL (p<0.0001, RM 2.8, IC 95% 2.2-3.4 y p<0.0001, RM 1.8, IC 95%=1.4-2.4, respectivamente). Se observó que una dureza del agua mayor a 400 ppm se asocia con una mayor prevalencia de litiasis (p=0.003, RM 1.9, IC 95% 1.21-2.94). Conclusiones. La prevalencia de litiasis urinaria en Yucatán es mayor a lo reportado en la literatura nacional e internacional. La dureza extrema del agua empleada para el consumo humano y el antecedente familiar de la enfermedad son factores de riesgo que requieren investigaciones futuras