Teresa Alarcón

Antibiotic resistance problems with Helicobacter pylori

Helicobacter pylori is very susceptible in vitro to most antibiotics, but when they are used in the clinical setting, eradication of the bacteria from the gastric mucosa is not obtained. Dual or triple therapy including two of the following antibiotics: amoxicillin, tetracycline, metronidazole or clarithromycin, plus a proton pump inhibitor, bismuth salt or ranitidine bismuth citrate is the most frequently used. Various in vitro susceptibility methods have been used: disk diffusion, agar dilution and Epsilometer test (E-test). Metronidazole resistance among H. pylori strains is now found worldwide, and resistance rates vary according to the population studied. It is higher in developing than in developed countries and it could reach 80-90% in Africa. The prevalence on clarithromycin resistance is much lower, usually below 10%, although very high values are reported in Peru. Infection with metronidazole- or clarithromycin-resistant H. pylori strains is correlated with treatment failure when using regimens including these antibiotics.

High Prevalence of Clarithromycin-Resistant Helicobacter pylori Strains and Risk Factors Associated with Resistance in Madrid, Spain

ABSTRACT Clarithromycin is one of the antibiotics used for the treatment of Helicobacter pylori infections, and clarithromycin resistance is the most important factor when it comes to predicting eradication failure. The present study analyzed H. pylori isolates for the presence of 23S rRNA gene mutations and determined the risk factors associated with resistance among H. pylori isolates collected in Madrid, Spain, in 2008. We studied 118 H. pylori strains isolated from the same number of patients. A total of 76.3% of the patients were born in Spain, 52.7% were children, 20.3% had previously been treated, and 66.1% were female. Clarithromycin resistance was determined by Etest. H. pylori strains were considered resistant if the MIC was ≥1 mg/liter. DNA extraction was carried out by use of the NucliSens easyMAG platform with NucliSens magnetic extraction reagents (bioMérieux). The DNA sequences of the 23S rRNA genes of clarithromycin-resistant and -sensitive strains were determined to identify specific point mutations. The vacA genotype and cagA status were determined by PCR. We found that 42 (35.6%) strains were resistant to clarithromycin by Etest. Etest results were confirmed by detection of the presence of point mutations in 34 (88.1%) of these strains. Eight H. pylori strains were resistant to clarithromycin by Etest but did not have a point mutation in the 23S rRNA gene. Mutation at A2143G was found in 85.3% of the strains, mutation at A2142G in 8.8%, and mutation at T2182C in 5.9%. Dual mutations were found in 8.8% of the strains. H. pylori clarithromycin-resistant strains were strongly associated with pediatric patients, with patients born in Spain, and with patients who had previously been treated (P ≤ 0.02). In addition, H. pylori strains resistant to clarithromycin more frequently presented the vacA s2/m2 genotype and were more likely to be cagA negative than susceptible strains (39.1% and 11.2%, respectively; P value < 0.001). We concluded that, in the present study, H. pylori clarithromycin-resistant strains are more frequently found in children, in patients mostly born in Spain, and in individuals who were previously treated for H. pylori infection and that these individuals are more likely colonized with a less virulent H. pylori strain.

Activities of Polymyxin B and Cecropin A-Melittin Peptide CA(1-8)M(1-18) against a Multiresistant Strain of Acinetobacter baumannii

ABSTRACT Polymyxin B (PXB) and the cecropin A-melittin hybrid CA(1-8)M(1-18) (KWKLFKKIGIGAVLKVLTTGLPALIS-NH2) were compared for antibiotic activity on reference and multiresistant Acinetobacter baumannii strains. Significant differences for both peptides were observed on their inner membrane interaction and inhibition by environmental factors, supporting the use of CA(1-8)M(1-18) as a potential alternative to PXB against Acinetobacter.

Characterization of the Gastric Microbiota in a Pediatric Population According to helicobacter pylori Status

Background: Helicobacter pylori colonizes the human stomach of approximately 50% of the world’s population, and increases the risk of several gastric diseases. The goal of this study is to compare the gastric microbiota in pediatric patients with and without H. pylori colonization. Methods: We studied 51 children who underwent gastric endoscopy because of dyspeptic symptoms (18 H. pylori positive and 33 negative). Gastric biopsies were obtained for rapid urease test, culture, histology and DNA extraction. H. pylori was quantified by quantitative polymerase chain reaction and the gastric microbiome studied by V4-16S ribosomal RNA gene high-throughput sequencing. Results: Bacterial richness and diversity of H. pylori-positive specimens were lower than those of negative, and both groups were clearly separated according to beta diversity. Taxonomic analysis confirmed that H. pylori-positive subjects had a higher relative abundance of Helicobacter genus (66.3%) than H. pylori-negative subjects (0.45%). Four phyla (proteobacteria, bacteroidetes, firmicutes and actinobacteria) accounted for >97% of all reads in both groups. Within proteobacteria, gamma- and betaproteobacteria were the most abundant for H. pylori-negative patients, whereas epsilonproteobacteria was for H. pylori positive. H. pylori-positive patients were associated with low body mass index. In the group of underweight patients (body mass index, <18.5), there were 46.1% of H. pylori-positive patients compared with 24% in the nonunderweight group (P = 0.049). Patients with active superficial gastritis in H. pylori-positive patients had the lowest alpha diversity (P = 0.035). Conclusions: We characterized the gastric microbiota for the first time in children with and without H. pylori and observed that when H. pylori is present, it tends to dominate the microbial community. In the H. pylori-negative patients, there was more relative abundance of gammaproteobacteria, betaproteobacteria, bacteroidia and clostridia classes and a higher bacterial richness and diversity.

Diagnóstico microbiológico de la colonizaciôn-infecciôn broncopulmonar en el paciente con fibrosis quística

Resumen La fibrosis quística (FQ) es la enfermedad hereditaria autosómica recesiva más frecuente en la población de origen caucásico. Está producida por mutaciones en el gen que codifica el regulador de la conductancia transmembrana de FQ. Este defecto conduce, entre otras, a la alteración de las secreciones respiratorias, lo que determina una predisposición para la colonización-infección broncopulmonar crónica, causa principal de la elevada morbilidad y temprana mortalidad de estos pacientes. La colonización por Staphylococcus aureus y Haemophilus influenzae es frecuente en niños menores de 10 años, aunque Pseudomonas aeruginosa con morfotipo mucoide es, con diferencia, el microorganismo más relevante en el adulto y causa principal del deterioro broncopulmonar progresivo. Como consecuencia del tratamiento antimicrobiano repetido y la alteración pulmonar se favorece el desplazamiento de los patógenos habituales y se aíslan con mayor frecuencia bacilos gramnegativos no fermentadores, entre los que destacan Stenothrophomonas maltophilia, Achromobacter spp. y Burkholderia cepacia complex. Las connotaciones particulares del propio proceso patológico y de los microorganismos implicados hacen recomendable reconocer el seguimiento microbiológico de la colonización-infección broncopulmonar en el paciente con FQ como una entidad diagnóstica propia. Abstract Cystic fibrosis (CF), a condition produced by mutations in the gene that encodes the cystic fibrosis transmembrane conductance regulator, is the most prevalent autosomal-recessive hereditary disease in caucasian populations. Among other repercussions, this defect leads to an alteration of respiratory secretions and determines a predisposition for chronic bronchopulmonary colonization-infection, which is the main driver of the high morbidity and early mortality of CF patients. Colonization by Staphylococcus aureus and Haemophilus influenzae is frequent in children younger than 10 years, but mucoid Pseudomonas aeruginosa is by far the most relevant pathogen in adults with CF and is responsible for the progressive bronchopulmonary deterioration. As a consequence of repeated, long-lasting antimicrobial treatments and deterioration of lung function, colonization by multidrug-resistant Gram-negative bacilli, such as Stenotrophomonas maltophilia, Achromobacter spp. and Burkholderia cepacia complex, is also frequent in adult CF patients. The special characteristics of the pathologic process and the microorganisms implicated in CF make it advisable to consider microbiological follow-up of chronic bronchopulmonary colonization-infection in these patients a specific diagnostic entity.

Carbapenemase-producing Escherichia coli is becoming more prevalent in Spain mainly because of the polyclonal dissemination of OXA-48

OBJECTIVES The objective of this study was to analyse the microbiological traits and the population structure of carbapenemase-producing (CP) Escherichia coli isolates collected in Spain between 2012 and 2014. METHODS Two-hundred-and-thirty-nine E. coli isolates non-susceptible to carbapenems were studied. The carbapenemase genes and the phylogenetic groups were characterized using PCR. MLST was carried out using the typing schemes of the University of Warwick and the Institut Pasteur. The diversity of the population structure was estimated by calculating a simple diversity index (SDI). RESULTS One-hundred-and-twenty-one isolates (50.6%) produced carbapenemases, of which 87 (71.9%) were OXA-48, 27 (22.3%) were VIM-1, 4 (3.3%) were KPC-2, 2 (1.7%) were NDM and 1 (0.8%) was IMP-22; 4 isolates were collected in 2012, 40 in 2013 and 77 in 2014. Ertapenem was more sensitive than imipenem or meropenem for screening for OXA-48-producing E. coli. Using the Warwick typing scheme, 59 different STs were identified, the most prevalent being ST131 (16.5%). The population diversity was higher among VIM-1-producing isolates (SDI = 81.5%) than among OXA-48-producing isolates (SDI = 44.8%). The Pasteur scheme had a higher discrimination capability (SDI = 55.4%) than the Warwick scheme (SDI = 48.8%). CONCLUSIONS A progressive increase in the prevalence of CP E. coli was observed, mainly due to the dissemination of OXA-48 producers. The most sensitive method for detecting decreased susceptibility of CP E. coli to carbapenems was disc diffusion with ertapenem using the EUCAST screening cut-offs. The spread of CP E. coli was due to a polyclonal population. The Pasteur scheme showed the highest discrimination power. Surveillance is crucial for the early detection of CP E. coli.

Factores microbiológicos que afectan a la erradicación de Helicobacter pylori en población adulta y pediátrica

Objetivos Estudiar factores microbiologicos como la sensibilidad a antimicrobianos y factores de virulencia de Helicobacter pylori relacionados con la erradicacion del microorganismo de la mucosa gastrica, tanto en poblacion pediatrica como adulta. Metodos Se obtuvieron 55 cepas aisladas a partir del cultivo de biopsias de 16 pacientes pediatricos y de 39 adultos. La sensibilidad antibiotica se realizo mediante el metodo de dilucion en agar y el estudio de los factores de virulencia, gen cagA y los alelos s1 y s2 del gen vacA mediante reaccion en cadena de la polimerasa (PCR). El seguimiento tras el tratamiento que se instauro con amoxicilina, claritromicina y omeprazol se realizo mediante la prueba del aliento con urea marcada. Se estudio la relacion entre la concentracion inhibitoria minima (CIM) a amoxicilina y claritromicina y la presencia de estos factores de virulencia con la erradicacion del microorganismo. Resultados La erradicacion fue del 69% (38/55), 71,7% en adultos y 62,5% en ninos. La resistencia a claritromicina y amoxicilina fue 14,5 y 0%, respectivamente. Las tasas de erradicacion globales en relacion con las variables estudiadas fueron del 75 y 53% en cepas con CIM de amoxicilina ≤ 0,016 mg/l y CIM de amoxicilina ≥ 0,032 mg/l (intervalo ≤ 0,008-0,5) (p > 0,05), 79 y 12% en cepas con CIM de claritromicina 0,05) y 82 y 62% en cepas s1 y s2 (p > 0,05), respectivamente. Conclusiones La infeccion por cepas con CIM mas altas a amoxicilina y claritromicina y por aislamientos cagA– y vacA s2 se relacionaron con tasas mas bajas de erradicacion de H. pylori, tanto en poblacion adulta como infantil en la terapia con amoxicilina, claritromicina y omeprazol.

Detection of Helicobacter pylori and the genotypes of resistance to clarithromycin and the heterogeneous genotype to this antibiotic in biopsies obtained from symptomatic children

The aim of this study was to use a commercially available kit (GenoType® HelicoDR; Hain Life Science, Germany) to detect Helicobacter pylori infection and clarithromycin resistance genotype in biopsies obtained from symptomatic children. RESULTS 111 out of 136 (81.6%) biopsies were H. pylori positive by genotype: 47 (42.3%) showed wild-type genotype, 53 resistant genotype (47.7%) and 11 heterogeneous genotype (9.9%). Culture was negative in 27 out of the 111 genotyped biopsies. Mutation A2143G (87.5%), followed by A2142G (7.5%) and double mutant A2142C-A2143G (5%) were found. The 11 heterogeneous genotype biopsies showed wild-type plus A2143G in 9 and plus A2142G in 2. CONCLUSIONS This kit is a rapid, culture-independent method for routine application in biopsies from the pediatric population that allows detection of clarithromycin resistance and heterogeneous genotypes. It is important to know the clinical impact of infection with this type of strains as well as the role in treatment success.

Helicobacter pyloriin Pediatrics

This review concerned the important pediatric studies published between April 2012 and March 2013. Symptomatology in Helicobacter pylori‐positive children is nonspecific, except for those suffering from peptic ulcer diseases. Investigation of H. pylori status in children and adolescents with sideropenic anemia is recommended, and it is the aim of several studies worldwide. Associations of H. pylori with plasma ghrelin levels as well as the negative association of H. pylori with atopic disease were interesting objectives for several studies this year. Success rates of sequential therapy tended to be lower in recent studies than in previous trials, which probably reflects the increase in macrolide resistance. A beneficial effect of probiotics was reported although not all trials supported this result in children. Intrafamilial transmission and young age could be major risk factors associated with reinfection in children.

Baseline and pre-operative 1-year mortality risk factors in a cohort of 509 hip fracture patients consecutively admitted to a co-managed orthogeriatric unit (FONDA Cohort)

INTRODUCTION The aim of this study was to determine the patient characteristics that predict 1-year mortality after a hip fracture (HF). METHODS All patients admitted consecutively with fragility HF during 1 year in a co-managed orthogeriatric unit of a university hospital (FONDA cohort) were assesed. Baseline and admission demographic, clinical, functional, analytical and body-composition variables were collected in the first 72 h after admission. A protocol designed to minimize the consequences of the HF was applied. One year after the fracture patients or their carers were contacted by telephone to ascertain their vital status. RESULTS A total of 509 patients with a mean age of 85.6 years were included. One-year mortality was 23.2%. The final multivariate model included 8 independent mortality risk factors: age >85 years, baseline functional impairment in basic activities of daily living, low body mass index, cognitive impairment, heart disease, low hand-grip strength, anaemia at admission, and secondary hyperparathyroidism associated with vitamin D deficiency. The association of several of these factors greatly increased mortality risk, with an OR (95% confidence interval [CI]) of 5.372 (3.227-8.806) in patients with 4 to 5 factors, and an OR (95% CI) of 11.097 (6.432-19.144) in those with 6 or more factors. CONCLUSIONS In addition to previously known factors (such as age, impairment in basic activities of daily living, cognitive impairment, malnutrition and anaemia at admission), other factors, such as muscle strength and hyperparathyroidism associated with vitamin D deficiency, are associated with greater 1-year mortality after a HF.