Microbiological and Molecular Characterization of Staphylococcus hominis Isolates from Blood

Background: Among Coagulase-Negative Staphylococci (CoNS), Staphylococcus hominis represents the third most common organism recoverable from the blood of immunocompromised patients. The aim of this study was to characterize biofilm formation, antibiotic resistance, define the SCCmec (Staphylococcal Chromosomal Cassette mec) type, and genetic relatedness of clinical S. hominis isolates. Methodology: S. hominis blood isolates (n = 21) were screened for biofilm formation using crystal violet staining. Methicillin resistance was evaluated using the cefoxitin disk test and the mecA gene was detected by PCR. Antibiotic resistance was determined by the broth microdilution method. Genetic relatedness was determined by pulsed-field gel electrophoresis (PFGE) and SCCmec typed by multiplex PCR using two different methodologies described for Staphylococcus aureus. Results: Of the S. hominis isolates screened, 47.6% (10/21) were categorized as strong biofilm producers and 23.8% (5/21) as weak producers. Furthermore, 81% (17/21) of the isolates were methicillin resistant and mecA gene carriers. Resistance to ampicillin, erythromycin, and trimethoprim was observed in .70% of isolates screened. Each isolate showed a different PFGE macrorestriction pattern with similarity ranging between 0–95%. Among mecA-positive isolates, 14 (82%) harbored a non-typeable SCCmec type: eight isolates were not positive for any ccr complex; four contained the mec complex A ccrAB1 and ccrC, one isolate contained mec complex A, ccrAB4 and ccrC, and one isolate contained the mec complex A, ccrAB1, ccrAB4, and ccrC. Two isolates harbored the association: mec complex A and ccrAB1. Only one strain was typeable as SCCmec III. Conclusions: The S. hominis isolates analyzed were variable biofilm producers had a high prevalence of methicillin resistance and resistance to other antibiotics, and high genetic diversity. The results of this study strongly suggested that S. hominis isolates harbor new SCCmec structural elements and might be reservoirs of ccrC1 in addition to ccrAB1 and mec complex A

The carriage of interleukin-1B-31*C allele plus Staphylococcus aureus and Haemophilus influenzae increases the risk of recurrent tonsillitis in a Mexican population

Abstract The aim of the present study was to estimate the relative contribution of immunogenetic and microbiological factors in the development of recurrent tonsillitis in a Mexican population. Patients (n = 138) with recurrent tonsillitis and an indication of tonsillectomy (mean age: 6.05 years±3.00; median age: 5 years, female: 58; age range: 1–15 years) and 195 nonrelated controls older than 18 years and a medical history free of recurrent tonsillitis were included. To evaluate the microbial contribution, tonsil swab samples from both groups and extracted tonsil samples from cases were cultured. Biofilm production of isolated bacteria was measured. To assess the immunogenetic component, DNA from peripheral blood was genotyped for the TNFA-308G/A single-nucleotide polymorphism (SNP) and for the IL1B -31C/T SNP. Normal microbiota, but no pathogens or potential pathogens, were identified from all control sample cultures. The most frequent pathogenic species detected in tonsils from cases were Staphylococcus aureus (48.6%, 67/138) and Haemophilus influenzae (31.9%, 44/138), which were found more frequently in patient samples than in samples from healthy volunteers (P<0.0001). Importantly, 41/54 (75.9%) S. aureus isolates were biofilm producers (18 weak and 23 strong), whereas 17/25 (68%) H. influenzae isolates were biofilm producers (10 weak, and 7 strong biofilm producers). Patients with at least one copy of the IL1B-31*C allele had a higher risk of recurrent tonsillitis (OR = 4.03; 95% CI = 1.27– 14.27; P = 0.013). TNFA-308 G/A alleles were not preferentially distributed among the groups. When considering the presence of IL1B-31*C plus S. aureus, IL1B-31*C plus S. aureus biofilm producer, IL1B-31*C plus H. influenzae or IL1B-31*C plus H. influenzae biofilm producer, the OR tended to infinite. Thus, the presence of IL1B-31*C allele plus the presence of S. aureus and/or H. influenzae could be related to the development of tonsillitis in this particular Mexican population

Measuring of Mycobacterium tuberculosis growth: a correlation of the optical measurements with colony forming units

The quantification of colony forming units (cfu), turbidity, and optical density at 600 nm (OD600) measurements were used to evaluate Mycobacterium tuberculosis growth. Turbidity and OD600 measurements displayed similar growth curves, while cfu quantification showed a continuous growth curve. We determined the cfu equivalents to McFarland and OD600 units

Actividad antimicrobiana y antioxidante de extractos etanólicos de hoja de Arbutus xalapensis Kunt, Mimosa malacophylla Gray y Teucrium cubense Jacquin

Se ha reportado un incremento en la emergencia de microorganismos resistentes a antibióticos, por lo que se busca desarrollar terapias para tratar dichas enfermedades. A este respecto se destaca el uso de productos naturales con propiedades antimicrobianas y antioxidantes. En la presente investigación se obtuvieron extractos etanólicos de hoja de Arbutus xalapensis, Mimosa malacophylla y Teucrium cubense las cuales fueron colectadas en la Localidad de Potrero Redondo, Santiago, Nuevo León, México para la determinación de dichas actividades. Estos extractos fueron probados contra cepas de importancia médica siendo la hoja de A. xalapensis quien manifestó la mayor actividad antimicrobiana (CMB = 2.9 ± 0.5 mg mL-1) en contra de Staphylococcus aureus ATCC 29213 que fue la cepa más sensible en el estudio. Además, este extracto obtuvo la mayor actividad antioxidante mediante los métodos de DPPH (1,206.6 ± 68.6 μmoles ET g-1) y ABTS•+ (1,750.7 ± 110.1 μmoles ET g-1).There has been a dramatic increase in the emergence of antibiotic resistant bacterial strains, because indiscriminate use of antibiotics. Therefore, it is vital to develop new therapies to treat these resistant pathogens. In recent years, interest in natural products has increased due to their biological activities, including, antimicrobial and antioxidant properties. In the present investigation, ethanolic leaf extracts of Arbutus xalapensis, Mimosa malacophylla and Teucrum cubense were obtained from plants collected in Potrero Redondo locality, Santiago Nuevo León, Mexico for determining the biological activities mentioned above. Extracts were tested against strains of medical importance being the A. xalapensis stem which had the best antimicrobial activity (CMB = 2.9 ± 0.5 mg mL-1) against Staphylococcus aureus. Furthermore, this extract óbtained the highest antióxidant activity by DPPH assay (1,206.6 ± 68.6 μmól ET g-1) and ABTS•+ (1,750.7 ± 110.1 μmól ET g-1)

Genetic and serologic surveillance of rotavirus with P[8] and P[4] genotypes in feces from children in the city of Chihuahua, northern Mexico

Rotavirus vaccine was developed using the most prominent G and P genotypes circulating in children population. Therefore, severe gastroenteritis has been reduced around the world. This study investigated the G and P rotavirus genotypes circulating in children from two hospitals in the city of Chihuahua, Mexico. Additionally, polyclonal antibodies against Rotavirus Wa strain were used to determine their homotypic and heterotypic reactivity to both P[8] and P[4] genotypes. G1, G2, and G3 VP7 genotypes and P[8] and P[4] VP4 genotypes were detected in common and uncommon combinations as well as mixed infectious. The predominant combination was G1P[8]. Phylogenetic analysis of VP4 gene revealed the presence of P[8]-1 and P[8]-3 lineages of P[8] genotype and P[4]-5 lineage of P[4] genotype. All but five G1P[8] rotavirus were detected by polyclonal anti-Rotavirus Wa strain. Mutation analysis revealed differences in three of the four neutralizing epitopes previously reported to VP8* subunit of VP4 protein. Results of this study offer insights over genetic variants of field rotavirus that could be detected in a homotypic and heterotypic way by antibodies elicited to rotavirus with P[8] genotype. [Int Microbiol 2016; 19(1):27-32]Keywords: rotavirus &middot; viral genotypes &middot; lineages of virus &middot; epitopes &middot; Chihuahua, Mexico&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp

Molecular and microbiological report of a hospital outbreak of NDM-1-carrying Enterobacteriaceae in Mexico

Abstract Objectives To characterize the microbiological, molecular and epidemiological data of an outbreak of carbapenem-resistant Enterobacteriaceae (CRE) in a tertiary-care hospital in Mexico. Methods From September 2014 to July 2015, all CRE clinical isolates recovered during an outbreak in the Hospital Civil "Fray Antonio Alcalde" in Jalisco, Mexico were screened for antimicrobial susceptibility, carbapenemase production, carbapenemase-encoding genes, and plasmid profiles. Horizontal transfer of imipenem resistance; and clonal diversity by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST); as well as biofilm production and the presence of 14 virulence genes were analyzed in selected isolates. Results Fifty-two carbapenem-resistant isolates corresponding to 5 species were detected, i.e., Klebsiella pneumoniae (n = 46), Enterobacter cloacae (n = 3), Escherichia coli (n = 1), Providencia rettgeri (n = 1) and Citrobacter freundii (n = 1) with carbapenemase encoding genes blaNDM-1 (n = 48), blaVIM (n = 3), blaIMP (n = 1) and blaKPC (n = 1) detected in these isolates. The blaNDM-1 gene was detected in plasmids from 130- to 170-kb in K. pneumoniae (n = 46); E. cloacae (n = 3), E. coli (n = 1) and P. rettgeri (n = 1). The transfer of plasmids harboring the blaNDM-1 gene was obtained in eight transconjugants. One plasmid restriction pattern was detected, with the blaNDM-1 identified in different restriction fragments. Predominant clone A of K. pneumoniae isolates archived 28/46 (60%) isolates and belongs to ST392. Besides, ST307, ST309, ST846, ST2399, and ST2400 were detected for K. pneumoniae; as well as E. cloacae ST182 and E. coli ST10. The fimA and uge genes were more likely to be identified in K. pneumoniae carbapenemsusceptible isolates (p =<0.001) and biofilm production was more liable to be observed in carbapenem-resistant isolates (p =<0.05). Conclusions Four Enterobacteriaceae species harboring the blaNDM-1 gene were detected in a nosocomial outbreak in Mexico; horizontal transfer and strain transmission were demonstrated for the blaNDM-1 gene. Given the variation in the size of the plasmid harboring blaNDM-1, complex rearrangements must also be occurring

Risk factors and molecular mechanisms associated with trimethoprim–sulfamethoxazole resistance in Stenotrophomonas maltophilia in Mexico

Abstract Purpose. Stenotrophomonas maltophilia is a multidrug-resistant opportunistic pathogen causing an increasing number of nosocomial infections. Our aim was to evaluate the risk factors and mechanisms associated with trimethoprim– sulfamethoxazole (SXT) resistance in S. maltophilia infections in Mexico. Methodology. Clinical isolates and patients’ demographic and clinical data were collected from February 2007 to August 2015 in two tertiary-care hospitals in Mexico. Antimicrobial susceptibility and analysis of sul and SmeABC and SmeDEF efflux pump overexpression were performed in all isolates. Results/Key findings. In the 9-year period, 196 patients infected with S. maltophilia were identified. Most patients were male, and the mean age was 46.2years. The mean Charlson score was 1.42, and the most frequent comorbidities were arterial hypertension (26.7%), type 2 diabetes (21.2%) and cerebral infarction (11.6%). High drug resistance to meropenem (93.4%), gentamicin (55.1%), ceftazidime (52.3%), cefotaxime (51.5%), amikacin (42.3%) and cefepime (32.1%), and lower resistance to ciprofloxacin (26.0%), SXT (25.0%), chloramphenicol (14.3%) and levofloxacin (2.6%) were detected. SXT resistance was not associated with the sul genes. SmeABC overexpression was associated with gentamicin (P=0.001) and levofloxacin resistance (P=0.041), whereas SmeDEF overexpression was associated with ceftazidime resistance (P=0.003). Prolonged hospitalization (�15days) was an independent risk factor for SXT-resistant S. maltophilia infections (OR=3.05; 95%CI=1.12– 8.86; P=0.029). Conclusion. Given the high SXT resistance rate, SXT is not an effective first-line therapy for our patients; instead, levofloxacin could be used as an appropriate therapeutic option against S. maltophilia infections

ACCIÓN INHIBITORIA DE PROBIÓTICOS SOBRE EL CRECIMIENTO AXÉNICO IN VITRO DEEntamoeba histolytica

Entamoeba histolytica es el protozoario parásito cosmopolita causante de la amibiasis y sus múltiples manifestaciones clínicas afectando con mayor frecuencia a los países en vías de desarrollo en donde existe hacinamiento y condiciones sanitarias deficientes e inadecuadas; en México representa un problema de saludpública por su frecuencia, morbilidad, mortalidad y fácil dispersión; para el control de la amibiasis y sus manifestaciones clínicas, se administra metronidazol como droga de elección, sin embargo este fármaco produce efectos secundarios indeseables. Reportes recientes indican que cultivos in vitro de E. histolytica han desarrollado resistencia a este fármaco. En este trabajo evaluamos el efecto de 1, 10, 20 y 100 mg/mL de liofilizados de medios condicionados con probióticos (Lactobacillus acidophilus, Lactobacillus casei y Lactococcus lactis) sobre el crecimiento axénico in vitro de E. histolytica. Las concentraciones ensayadas mostraron diferencia estadística significativa (ANOVA p=0.05) como inhibidores del crecimiento in vitro de Entamoeba histolytica HM1-IMSS. Estos resultados abren la posibilidad de contar con una alternativa nutricional para la prevención y tratamiento de la amibiasis sin presentar efectos secundarios indeseables.Palabras claves: Entamoeba histolytica, Lactobacillus acidophilus, Lactobacillus casei, Lactococcus lactis, cultivo axénico, probióticos.Entamoeba histolytica, Lactobacillus acidophilus, Lactobacillus casei, Lactococcus lactis, axenic culture, probiotics