Asociación en un mismo plásmido de blaVIM-1 y qnrS2 en Klebsiella pneumoniae y Klebsiella oxytoca aisladas en Sevilla

Background

Combined resistance to quinolones and β-lactams is common in Enterobacteriaceae. The appearance in enterobacteria coding for metallo-β-lactamases and determinants of plasmid-mediated quinolone resistance are an emerging problem in our country.

Methods

The susceptibility was determined by E-test. The resistance genes were detected by PCR and the corresponding plasmids were characterised.

Results

This study describes 2 strains (1 Klebsiella oxytoca, 1 Klebsiella pneumoniae) carrying the genes qnrS2 and blaVIM-1 in a transferable plasmid of 70-Kb isolated in surveillance cultures at the University Hospital Virgen Macarena in Seville.

Conclusion

This is the first combination of qnrS2 and bla_VIM-1 on the same non-typeable plasmid isolated in our centre.     

Erradicación de un brote nosocomial de infecciones por Acinetobacter baumannii multirresistente tras el ajuste de cargas de trabajo y refuerzo de precauciones específicas

Introduction

During 2009, an outbreak of multidrug-resistant Acinetobacter baumannii (MDR A. baumannii) infections was detected in a 27-bed intensive care unit, resulting in 25 cases being infected.

Methods

A matched case-control study was conducted to identify risk factors for infection. The colonization pressure, or the proportion of other patients colonized by MDR A. baumannii, was estimated. TISS-28 and Omega scores of each patient were calculated to evaluate nursing work requirements. Conditional logistic regression analyses were carried out.

Results

Breakdowns in hand washing and glove use were observed. Infected patients (cases) were more likely than paired controls to have had longer exposure to invasive devices and antimicrobial treatment. The independent risk factors identified by the multivariate analysis were, mechanical ventilation [odds ratio (OR) = 1.03; 95% confidence interval (CI), 1.01-1.05; P = .01], and exposure to an infected or colonized patient [OR = 1.7; 95% CI, 1.1-2.6; P = .02). A combined infection control strategy was implemented, including strict compliance with isolation precautions, grouping of patients, reinforcing cleaning and disinfection of surfaces, and a decrease in work load. Subsequently, a sharp reduction in the incidence MDR A. baumannii infections was shown. Therapeutic activity scores were significantly higher for cases than for controls.

Conclusion

The results suggest patient-to-patient transmission of MDR A. baumannii. Reinforcement of specific procedures and work load adjustment were essential to eradicate this outbreak.     

Prevalencia del determinante de resistencia plasmídica a quinolonas aac(6’)-Ib-cr en cepas de Escherichia coli y Klebsiella pneumoniae productoras de BLEE aisladas en diez hospitales de Chile

Introduction

The frequency of aac(6′)-Ib-cr gene in ESBL-producing strains of Klebsiella pneumoniae and Escherichia coli is unknown, in Chile.

Methodology

The aac(6′)-Ib and aac(6’)-Ib-cr genes were investigated using polymerase chain reaction (PCR), restriction fragment length polymorphism (RFLP), and sequencing, in strains isolated from 10 Chilean hospitals between 2008-2009.

Results

The aac(6’)-Ib-cr gene was detected in 54% of K. pneumoniae and 74% of E. coli strains. The CIM₅₀ of CIP was higher among strains harboring aac(6’)-Ib-cr, 8 times higher in K. pneumoniae and 4 times higher in E. coli. Moreover, both aac(6’)-Ib and aac(6’)-Ib-cr were simultaneously found in 13 K. pneumoniae and 3 E. coli isolates.

Conclusion

This is the first report of aac(6’)-Ib-cr in ESBL-producing strains of K. pneumoniae and E. coli isolated from in-patients in Chilean hospitals located along an area of more than 2,800 Km.     

Actualización de la eficacia de la terapia triple para la infección por Helicobacter pylori y de la resistencia a claritromicina en España (2007-2012)

Introduction

Triple therapy, which remains the standard treatment for Helicobacter pylori infection, should be discouraged when its efficacy is lower than 80% or when clarithromycin resistance rates are above 15-20%.

Aim

To update the available evidence on the effectiveness of triple therapy and clarithromycin resistance rates in adults in Spain over the last 6 years.

Methods

A literature search (2007-2012) was conducted in Medline and the abstracts books of the annual meetings of several Spanish gastroenterological and microbiological congresses. The search terms were «Helicobacter pylori», «Spain» and «clarithromycin». Studies were selected if they included triple therapy consisting of a proton pump inhibitor with clarithromycin and amoxicillin or if they analyzed H. pylori clarithromycin susceptibility in treatment-naïve patients.

Results

There were five articles and nine abstracts (3147 patients) on triple therapy, which showed a mean cure rate of 70.8% (95% CI = 66-76%). When stratified by the duration of therapy, the mean cure rates were 68.8% (60-76%) for 7-day regimens and 71.76% (68-78%) for 10-day regimens. For clarithromycin resistance rates, four articles and five abstracts (1709 patients) revealed a mean resistance rate of 18.3% (13-22%).

Conclusions

The efficacy of triple therapy seems to be unacceptable in recent studies conducted in Spain, possibly associated with clarithromcyin resistance rates higher than previously reported.     

Resistencia a antibióticos y factores de virulencia en aislados clínicos de Salmonella enterica

Introduction

The increase of Salmonella enterica isolates multi-resistant to different antibiotics, including β-lactams and fluoroquinolones, is a problem of clinical importance. The dissemination of Salmonella Typhimurium resistant to ampicillin (AMP)-chloramphenicol (CHL)-streptomycin (STR)-sulphonamides and (SUL)-tetracycline (TET), that harbour the Salmonella Genomic Island type 1 (SGI1), and the acquisition of transferable genetic material have favoured the multi-resistance in this genus.

Methods

A total of 114 clinical S. enterica isolates were studied (period 2009-2010). The susceptibility to 20 antibiotics was determined by disc diffusion and microdilution. The antimicrobial resistance mechanisms and the integrons were analysed by PCR, and sequencing in the AMP^R isolates. In all the bla_PSE-1-positive isolates, the clonal relationship was determined by PFGE, as well as the presence of SGI1 and 29 virulence genes by PCR.

Results

Eighteen different serotypes were found among the 114 isolates studied, Typhimurium (61%) and Enteritidis (16%) being the most prevalent. High percentages of resistance to SUL (68%), TET (58%), AMP (55%) and STR (46%) were observed. The great majority (92%) of 63 AMP^R isolates were multi-resistant, with the AMP-STR-TET-SUL phenotype (19 isolates) being the most frequent one and associated with the bla_TEM-1b + strA-strB + tet(B) + sul2 genotype. Class 1 integrons (7 different structures) were observed in 48% AMP^R isolates, highlighting the bla_OXA-1 + aadA1 structure (8 isolates), one empty integron and non-classical integrons (5 isolates). The bla_PSE-1 gene was detected inside the classical SGI1 structure in 13 clonally-related isolates that showed the same virulence profile.

Conclusions

The high percentage of multi-resistant S. enterica isolates, especially associated to S. Typhimurium, to the AMP, STR, TET and SUL phenotype, and to the bla_TEM-1b + strA-strB + tet(B) + sul2 genotype, shows an important risk of possible failures in the treatment of serious infections caused by this serotype.     

Nuevo clon de Acinetobacter baumannii ST187 responsable de un brote en una unidad de cuidados intensivos

Introduction

An ICU-outbreak caused by a novel Acinetobacter baumannii clone is described.

Methods

An active search of carriers and environmental reservoirs was carried out. Carbapenemases genes were studied using multiplex-PCR and genotypic analysis by rep-PCR, PFGE and MLST.

Results

A total 26 infected patients and 10 carriers were identified. A. baumannii was recovered from infusion pumps, walls, floor and washbasins. Phenotypic/genotypic analysis showed clonal expansion of a unique clone ST-187 producer of type OXA-24 and OXA-51 carbapenemases.

Discussion

This is the first outbreak caused by ST-187 (ECI/GCI) multiresistant A. baumannii.     

Neisseria gonorrhoeae: resistencias antimicrobianas y estudio de la dinámica poblacional. Situación en 2011 en Barcelona

Background

Due to the high rates of antimicrobial resistance to certain antibiotics, together with the emergence of Neisseria gonorrhoeae (NG) with reduced susceptibility and resistance to third-generation cephalosporins, gonococcal infection is becoming a public health problem. The objectives of the study were: To keep track of the antimicrobial susceptibility of NG strains obtained from January to August 2011. To study the population dynamics.

Methods

The antimicrobial susceptibility was studied by disk-diffusion and E-test. The genotyping was performed by NG-MAST method.

Results

Of a total of 100 strains studied, 59% showed intermediate sensitivity to penicillin and 9% were resistant. According to EUCAST, we detected 3 gonococci with reduced susceptibility to ceftriaxone, 10 to cefixime and one with high-level resistance to both antibiotics (MIC 1.5 μg/ml). MIC₅₀ and MIC₉₀ to cefixime were 0.016 and 0.125 μg/ml, respectively, whereas to ceftriaxone they were < 0.016 and 0.064 μg/ml, respectively. Almost all (99%) of the strains were resistant to doxycycline, 53% to ciprofloxacin, 3% to azithromycin, and 1% to spectinomycin. The most prevalent ST was ST1407, predominantly associated to resistance or reduced sensitivity to cephalosporins or macrolides.

Conclusions

NG has developed significant rates of resistance to various antibiotics. One strain has been detected with high level resistance to third generation cephalosporins, and several strains with reduced susceptibility. An increase in MIC₅₀ and MIC₉₀ to these antibiotics has also been observed. NG population structure remains stable and common to the rest of Europe, although two new ST (ST7226 and ST7227) have been identified that could be selected and acquire high levels of resistance to cephalosporins.     

Caracterización de cepas de Staphylococcus epidermidis y S. haemolyticus resistentes a meticilina y linezolid en un hospital español

Introduction

Linezolid resistance is mainly due to mutations in the 23S rRNA target. The aim of this study was to characterize linezolid and methicillin resistant Staphylococcus epidermidis (SE-LM^R) and S. haemolyticus (SH-LM^R) strains detected in a Spanish hospital.

Methods

SE-LM^R and SH-LM^R strains obtained in the period June 2009-August 2011 in a second level hospital were recorded along with the epidemiological characteristics of the patients. These strains were typed, and their resistance, phenotype, genotype and the factors determining their virulence were analysed.

Results

Linezolid resistance was explained by the presence of G2603T mutation (23S rRNA) and aminoacid changes in L3 and L4 ribosomal proteins. The 25 SE-LM^R strains belonged to sequence type ST2, presented SCCmec type III, and two different PFGE patterns. The two SH-LM^R strains showed non-typeable SCCmec. SE-LM^R strains harboured the resistance genes aac(6’)-aph(2”), and dfrS1. SH-LM^R strains contained these genes and the gene erm(C). No lincomycin resistance mechanism was identified in SE-LM^R strains regardless of showing lincomycin resistance and diminished susceptibility to clindamycin.

Conclusions

Linezolid resistance is of concern in hospitals, and requires continued vigilance. Several linezolid resistance mechanisms (mutation in 23S RNAr and amino acid changes in L3 and L4) were identified in this study.     

Epidemiología y características clínicas de los episodios de bacteriemia por Streptococcus pyogenes en Cartagena (Murcia)

Introduction

A gradual increase in severe cases due to Streptococcus pyogenes or Streptococcus beta-hemolytic group A (SGA), has been detected in the last few decades.

Methods

Retrospective study of bacteremia due to S. pyogenes detected between January 2009 and January 2013 in Cartagena. The annual incidence for severe bacteremia has been estimated.

Results

Thirteen cases of SGA bacteremia were recorded. The incidence increased from 0.37 in 2009 to 2.5 cases/100,000 inhabitants in 2012. The predominant focus was skin and soft tissue infections (53%). Early mortality was 20%.

Conclusion

Severe streptococcal disease is rare, but affects individuals with good functional status, and is associated with a high mortality.     

Descripción de casos de derrame pleural secundario a Streptococcus milleri

In this study we analyzed the characteristics of patients with pleural effusion secondary to Streptococcus milleri studied retrospectively between January and March 2013 and found seven patients with a mean age of 60 years, 43% of which were smokers and 57% with a drinking habit. The most common associated factors were alcoholism, previous pneumonia and diabetes. Other bacteria were identified as Enterobacter aerogenes, Bacteroides and Prevotella intermedia capillosus in two patients. The mean duration of antibiotic therapy was 28 days; six patients underwent pleural drainage by chest tube and one patient needed surgery due to poor clinical progress. The mean duration of hospitalization was 30 days with satisfactory outcome in all cases, despite some changes in residual function.     

Significado clínico del aislamiento de Staphylococcus aureus en muestras de orina

Introduction

To evaluate the clinical significance of the isolation of Staphylococcus aureus in urine samples.

Methods

A retrospective study was performed on adult patients identified from a microbiology database in a 200-bed general hospital between the years 2000 and 2009. The demographic data, comorbidities, and risk factors, were reviewed, particularly those associated with the concomitant isolation of S. aureus in blood cultures.

Results

The frequency of S. aureus found in urine samples was 0.63%. A total of 43 patients (mean age 68.7 years [SD ± 16], and 58.1% males) were identified in the database. A Charlson comorbidity index > 3 was observed in 20.9%. Concurrent bacteremia was seen in 48.8%. Two groups of patients were distinguished: with concomitant bacteremia (n = 21) or without (n = 22). Intervention in the urinary tract significantly predicted (P = .00004) bacteriuria without bacteremia (81.8%), compared to bacteremia cases (19%). The attributable mortality was 47.6% in patients with bacteremia compared to non-bacteremia (no deaths), even though the appropriate antibiotic treatment was more frequent among patients with bacteremia (92% and 60%, respectively).

Conclusion

The presence of S. aureus in urine was accompanied by bacteremia in half of the cases, but in patients without previous urinary tract intervention such a possibility increased to 81%. Concomitant bacteremia predicts a worse prognosis even with appropriate treatment.     

Caracterización genética por reacción en cadena de la polimerasa de Giardia intestinalis en muestras de humanos y perros del Caribe colombiano

Introduction

Giardia intestinalis (G. Intestinalis) is a protozoan that causes diarrheal disease and malabsorption syndrome in humans and other mammals. It presents a high genetic diversity evidenced in the recognition of 7 genotypes (A-G). Genotypes A and B are commonly associated to humans and domestic animals such as dogs. The aim of this study was to conduct a preliminary genetic characterization of G. intestinalis in humans and dogs from two cities on the Caribbean coast of Colombia.

Methods

Sampling areas were selected according to the highest numbers of acute diarrheal disease. Stool samples were collected from children under 7 years old, with positive medical tests for G. intestinalis. Cysts were purified by sucrose gradient and DNA samples were isolated by extraction with organic solvents. Molecular characterization was performed by amplifying the gene triose phosphate isomerase (tpi) by using a semi-nested PCR.

Results

A total of 202 samples of DNA were obtained; of these, 111 were positive in coproparasitological analysis (13 dogs and 98 children). Genotype distribution in positive samples was: 5.1% belonged to genotype A and 92.3% to genotype B. Genotype B was present in humans and animals.

Conclusions

The most common genotype in both human and animal samples was genotype B, suggesting a zoonotic transmission cycle.     

Detección fenotípica de mecanismos de resistencia en microorganismos grampositivos

Antimicrobial resistance mechanisms among clinically relevant gram-positive microorganisms can be demonstrated using phenotypic tests that enable the interpretation of underlying mechanisms responsible for the in vitro resistance. The reporting of these mechanisms, either inferred or demonstrated, helps in the adjustment of clinical treatments and the epidemiological follow up of resistance traits. In the present work, phenotypic tests for detection of antimicrobial resistance mechanisms involving the most frequent antimicrobial families used against Staphylococcus spp., Enterococcus spp. and Streptococcus pneumoniae are analysed. In the case of Staphylococcus, phenotypic tests to reveal the mechanisms of resistance against beta-lactams, macrolides, lincosamides and streptogramin B (MLS_B), as well as intermediate susceptibility to glycopeptides, resistance to aminoglycosides, mupirocin and linezolid are reviewed. Tests to detect glycopeptide resistance and high-level aminoglycoside resistance among enterococci are analysed. Detection of penicillin resistance, as well as diminished susceptibility to third generation cephalosporins, together with diminished susceptibility or even resistance to fluoroquinolones is also detailed.     

Sensibilidad a azitromicina y otros antibióticos en aislados recientes de Salmonella,Shigella y Yersinia

Introduction

Azithromycin represents an alternative option to treat bacterial diarrhea when the antibiotic therapy is indicated. Little is known regarding the susceptibility to azithromycin in enteropathogens in Spain.

Methods

The MICs of azithromycin were determined by E-test against Salmonella non-typhi (SNT), Shigella and Yersinia isolates collected over the last three years (2010-2012). In addition, the susceptibility to other antibiotics usually used to treat gastrointestinal diseases was determined in these isolates by using a microdilution method.

Results

A total of 139 strains of SNT, Shigella and Yersinia were studied. All of them, except one strain, had a MIC ≤ 16 mg/L of azithromycin. In the adult population, 14.7% and 40.6% of SNT and Shigella isolates, respectively, were resistant to at least 2 of following antibiotics: amoxicillin, trimethoprim-sulfamethoxazole and ciprofloxacin. In the pediatric population, 10% of SNT clinical isolates and 28.6% (2/7) of Shigella isolates were resistant to amoxicillin and trimethoprim-sulfamethoxazole.

Conclusions

In our experience, azithromycin would be a useful antibiotic alternative to treat bacterial diarrhea.     

Colonización nasal por Staphylococcus aureus en estudiantes de medicina: importancia en la transmisión hospitalaria

Background

Staphylococcus aureus is the main pathogen causing nosocomial infections. Health professionals, including medical students, could be a source of transmission. The aims of the study were to determine the rate of nasal carriage of S. aureus susceptible and resistant to methicillin (MRSA) and evaluate the knowledge and adherence that students had about hand hygiene.

Methods

The study included medical students attached to the Hospital Universitario 12 de Octubre (Madrid, Spain). We collected samples from both nasal vestibules, and the antimicrobial susceptibility was determined on all isolates. Data collection was performed using a self-administered questionnaire that included risk factors for colonization, hygiene habits and knowledge of hand hygiene protocols.

Results

Of the 140 students included, 55 (39.3%) were colonized by S. aureus, and 3 (2,1%) by MRSA. The exposure to antibiotics in the last 3 months was lower in colonized students (12.3% vs. 25.9%, P = .03). Self-assessment showed that 56.4% of students almost never washed their hands before to attending to the first patient, and only 38.6% always washed after examining patients. More than a third (35.7%) ignored the hand hygiene protocol, and 38.6% had not received specific formation.

Conclusions

Medical students should be included in hospital infection control programs. Hand hygiene training should be given to students before they begin their practices in the hospital.     

Aumento significativo de la colonización por Staphylococcus aureus entre los estudiantes de medicina durante la realización de las prácticas en el hospital

Introduction

Staphylococcus aureus is a pathogen of major concern. The emergence of methicillin-resistant S. aureus (MRSA) has increasingly complicated the therapeutic approach of hospital-acquired infections. Surveillance of MRSA and control measures must be implemented in different healthcare settings, including screening programs for carriers. Our first aim was to determine the prevalence of methicillin-susceptible S. aureus (MSSA) and MRSA nasal carriage in medical students from the Clínico San Carlos Hospital (Madrid). As the MRSA carrier rate in healthcare workers is higher than in the general population, we hypothesised that carrier rate could be increased during their clinical practice in their last three years.

Methods

We performed an epidemiologic al study of the prevalence of S. aureus colonisation among a group of medical students, who were sampled in 2008 in their third-year, and in 2012 when this class was in its sixth year.

Results

We have found a significant increase in MSSA carriage, from 27% to 46%. There were no MRSA colonisations in the third-year, but one was found in the sixth-year group. The large majority of strains (89%) of strains were resistant to penicillin, and 27% to erythromycin and clindamycin. As 19 coagulase-negative Staphylococcus MR were also identified, a horizontal transfer of genes, such as mecA gene to S. aureus, could have occurred.

Conclusions

Medical students are both, at risk for acquiring, and a potential source of nosocomial pathogens, mainly MSSA. Therefore, they should take special care for hygienic precautions, such as frequent and proper hand washing, while working in the hospital.