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.     

Molecular epidemiology and antimicrobial susceptibility of Campylobacter coli clinical isolates

Introduction

Campylobacter spp. is a major cause of acute bacterial diarrhea in humans worldwide, and C. coli is responsible for 10% of the cases.

Materials and methods

A study was made of the antimicrobial susceptibility using the E-test^®, and the clonal relationship using PCR-RFLP, of the flaA gene, as well as PFGE techniques on 43 C. coli clinical isolates.

Results

Only 49% and 2% of the isolates were susceptible to erythromycin and ciprofloxacin, respectively. Imipenem and clindamyicn, with 100% and 84% of the strains, respectively, being susceptible, were the most active antimicrobials. The PCR-RFLP of flaA gene technique grouped fourteen isolates into six clusters, while the PFGE technique grouped eleven isolates into five clusters.

Conclusion

Ciprofloxacin and erythromycin are not suitable for the treatment of C. coli infections. Clindamycin could be considered as a therapeutic alternative in cases of enteritis, while imipenem is the best alternative for extra-intestinal infections. Both PFGE and PCR-RFLP can be useful to detect clones.     

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.     

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.     

Aplicación del análisis de los polimorfismos de los tamaños de los fragmentos de restricción del gen flaA amplificado por reacción en cadena de la polimerasa y resistotipo para identificar potenciales brotes de campilobacteriosis no diagnosticados en España

Introduction

Outbreaks of campylobacteriosis are infrequent and usually involve a low number of patients, although it is estimated that many more remain undiagnosed. The most successful techniques for outbreak investigation in Campylobacter spp. (PFGE, MLST) have the drawback of being laborious and not available in many laboratories.

Methods

During the year 2008, 352 isolates of C. jejuni and C. coli from 16 hospitals were received in our laboratory. All strains were genotyped by RFLP-PCR-flaA (flaA type) and phenotyped with their resistotype. It was established that the strains of the same species from the same hospital, isolated over a period of up to 11 days, with MIC values of ± 1 dilution with the same flaA type could belong to an outbreak. Strains that met these criteria would be later subtyped by KpnI-PFGE and MLST.

Results

A total of 23 out of 352 isolates, distributed in 10 groups, met the criteria for being associated with putative undiagnosed outbreaks. The similarity of the PFGE-profiles in 8 groups was greater than 95% among the isolates from each group. In 7 of the groups, the sequence types (MLST) were coincident.

Conclusions

The use of 2 easy markers (resistotype and RFLP-PCR-flaA) may detect isolates probably belonging to an undiagnosed outbreak of campylobacteriosis. Accurate diagnosis requires other molecular markers and epidemiological data of each isolate. The study suggests that, as in other countries, the number of outbreaks of campylobacteriosis in Spain is probably underestimated.     

Conservative treatment of staphylococcal prosthetic joint infections in elderly patients

Background

We report the outcome of debridement and prosthesis retention plus long-term levofloxacin/rifampicin treatment of prosthetic joint infections.

Methods

Staphylococcal prosthesis joint infections were defined by positive culture of joint aspirate, intraoperative debridement specimens, or sinus tract discharge in the presence of clinical criteria. Patients received long-term oral levofloxacin 500 mg and rifampicin 600 mg once per day. Sixty patients (age 74.6 ± 8.4 years) were included.

Results

Coagulase-negative staphylococci were significantly more frequently isolated in the knee (78.6%; P = .00001). Of the Staphylococcus aureus isolates, 33.3% were methicillin-resistant. Time from arthroplasty to symptoms onset was higher (P = .03) in coagulase-negative staphylococci infections. Global failure was 35% (higher for the knee) and ranged from 16.6% to 69.2% (P = .0045) in patients with symptoms duration of less than 1 month to more than 6 months. A shorter duration of symptoms (P = .001) and time to diagnosis (P = .01) were found in cured patients versus patients showing failure. Among those with S. aureus infections, a higher failure rate was found with methicillin-resistance.

Conclusions

Efficacy was higher in patients with shorter duration of symptoms, earlier diagnosis, hip infections, and methicillin susceptibility.     

LCT-13910C > T polymorphism-associated lactose malabsorption and risk for colorectal cancer in Italy

Background

The activity of epithelial lactase (LCT) associates with a polymorphism 13910 bp upstream the LCT-encoding gene (LCT-13910C > T). The relationship between LCT-13910C > T polymorphism and risk for colorectal cancer is unclear.

Aims

We examined the relationship between the LCT-13910C > T polymorphism causing lactose intolerance and risk for colorectal cancer/polyps onset in the Italian population.

Patients and methods

793 subjects (306 with colorectal cancer, 176 with polyps and 311 controls) were genotyped for the LCT-13910C > T variant by TaqMan real time-PCR.

Results

Lactose malabsorption linked to the CC genotype did not associate with an increased risk for either colorectal cancer (OR = 1.041; 95% CI = 0.751–1.442; p = 0.868) or polyps (OR = 0.927; 95% CI = 0.630–1.363; p = 0.769). There was no association with colorectal cancer/polyps site. 60% of the subjects overall bore the CC genotype.

Conclusion

In the Italian population the LCT-13910C > T polymorphism is not associated to the risk for colorectal cancer or polyps.     

Escherichia coli O25b:H4/ST131 are prevalent in Spain and are often not associated with ESBL or quinolone resistance

Introduction

A multiresistant CTX-M-15-producing clonal group of Escherichia coli isolates, namely O25b:H4/ST131, has recently emerged in three continents. At this moment, appropriate studies to assess the real prevalence of this successful lineage are still scarce.

Methods

In a prospective study in the south of Spain, among all clinical E. coli isolates recovered in Seville during a 30 week period in 2010, ST131 was screened by using PCR for O25b/pabB3/B23 traits. ESBL enzymes were characterized by PCR and sequencing. Genetic relatedness was performed by XbaI PFGE.

Results

This clonal group was found to be prevalent (12.5% of all E. coli isolates), and only 37 (6.8% of ST131 isolates) were ESBL producers. Among 25 characterized ESBL-producing ST131 isolates, 96% harbored CTX-M-15. ST131 isolates were more frequently resistant to amoxicillin/clavulanate, aminoglycosides and fluoroquinolones in both ESBL and non-ESBL producers groups. XbaI PFGE performed on 88 ST131 isolates showed three pulsotypes, which included ≥4 isolates each (25% of all typed ST131 isolates), and 11 pulsotypes, which contained 2–3 isolates each. Three of 14 pulsotypes of this clonal group included both nalidixic acid-resistant and susceptible isolates, and five pulsotypes included both ESBL and non-ESBL producers.

Conclusions

Our findings suggest that O25b/ST131 is a prevalent clone in our area, and the observed prevalence of ESBL-producers within this clone is similar to that found in the total isolates of this species. Certain pulsotypes among ST131 clone that showed a greater expansion, and ESBL genes acquisition or quinolone resistance could explain part of this prevalence.     

Aumento de la expresión de las moléculas CD11c y CD103 en neutrófilos de sangre periférica tratados con una formulación de ribosomas bacterianos y proteoglicanos de Klebsiella pneumoniae

Aim

To evaluate the effect of a preparation with bacterial ribosomes and proteoglycans from Klebsiella pneumoniae «R» on the in vitro expression of CD11c and CD103 molecules in neutrophils from peripheral blood.

Methods

Isolation of neutrophils from peripheral blood with Ficoll-Paque, incubation with R and detection of CD11c and CD103 through flow cytometry.

Results

Six hours after the incubation period, CD11c expression increased significantly compared with the control with 125 and 500 μg/ml of R (P = .017 and P = .006, respectively). CD103 expression induced with 125 μg/ml of R after 6 hours was significantly higher than that observed after 4 hours at the same concentration (P = .014) and that found with 62.5 μg/ml (P = .017) of R.

Conclusions

The increased expression of CD11c and CD103 induced by R in the neutrophils could contribute to the R mechanism against respiratory pathogens.     

Antibiotic resistance patterns of Acinetobacter calcoaceticus–A. baumannii complex species from Colombian hospitals

Introduction

Only automated phenotypic methods are currently used in Colombian hospitals for identifying isolates of the Acinetobacter calcoaceticus–A. baumannii complex (ACB). The phenotypical similarities in these species mean that they cannot be differentiated by manual or automated methods, thereby leading to their identification as A. baumannii, or ACB complex in clinical settings. Our objective was to identify to the species level 60 isolates, from four hospitals, evaluate their antibiotic susceptibility, and detect resistance-related genes.

Methods

16S–23S rRNA internal transcribed spacer (ITS) region and rpoB gene partial sequences were amplified. Resistance genes for cephalosporin, carbapenem and aminoglycoside were detected by PCR. Possible mutations in the quinolone resistance-determining region (QRDR) were evaluated. The association of ISAba-1 with bla_OXA and bla_ADC genes was determined by PCR. Amplification products of ITS region, rpoB gene and some resistance genes were sequenced and compared using the BLAST tool.

Results

16S–23S rRNA ITS region and partial rpoB gene sequence analysis allowed 51isolates to be identified as A. baumannii, 8 as A. nosocomialis, and 1 isolate as A. pitti. A. baumannii isolates were highly resistant to all antibiotics tested, while the others were susceptible to ciprofloxacin and ampicillin/sulbactam. Quinolone resistance, found only in A. baumannii, was associated with mutations in the QRDR region of gyrA and parC genes.

Conclusion

This is the first investigation in Colombia that has identified ACB complex species using molecular methods, and determined differences in antibiotic resistance and resistance genes among the species. It is of the highest importance to identify isolates to the species level for future resistance and epidemiology studies in our region.     

Infección por Rothia mucilaginosa. ¿Un patógeno respiratorio?

Introduction

To describe the spectrum of infections caused by Rothia mucilaginosa.

Methods

Retrospective study of 20 cases diagnosed with R. mucilaginosa from 2009 to 2012.

Results

Pulmonary infection was the most frequent clinical presentation (n = 14, 70%): bronchiectasis infected (10), followed by pleural empyema (2), pneumonia (1) and acute bronchitis (1). Two episodes were of gastrointestinal origin: cholangitis secondary to biliary drainage and secondary peritonitis. Two episodes included bacteremia in patients with hematological malignancy. One patient had a surgical wound infection with bacteremia, and another had a bacteremic urinary tract infection in a patient with nephrostomy.

Discussion

R. mucilaginosa may be responsible for infections of the lower respiratory tract in predisposed patients.     

Efecto de la infección por Clostridium difficile sobre la estancia hospitalaria. Estudio de cohortes

Introduction

Clostridium difficile is responsible for a spectrum of diseases known as “Clostridium difficile infection” (CDI). It is currently the leading cause of nosocomial diarrhea in developed countries. This infection has been associated with both increased hospital stay and mortality, and to a greater likelihood of readmission. In our country these undesirable effects have not yet been characterized. Our objective was to quantify the increase in hospital stay attributable to infection by C. difficile.

Methods

A retrospective cohort study matched by age, sex and admission date, was conducted in a tertiary care university hospital during an outbreak of nosocomial transmission of CDI.

Results

The cohort study included 38 infected, and 76 non-infected patients. Patients who developed CDI showed a higher proportion of malnutrition at admission (OR = 10.3; 3.6 to 29.6), were exposed to a wider range of antibiotics (mean difference = 1.5; 0.7-2.2), had a higher mortality (31.6% vs. 6.6% of controls, P < .001), and a longer hospital stay (median 31.5 days versus 5.5 days for controls, P < .001). After adjustment, infection by C. difficile was associated with an increase in hospital stay of 4 days (P < .001).

Conclusions

C. difficile infection has important consequences on the length of hospital stay, and therefore on health costs.     

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.     

Combined effect of linezolid and N-acetylcysteine against Staphylococcus epidermidis biofilms

Introduction

Staphylococcus epidermidis is an organism commonly associated with infections caused by biofilms. Biofilms are less sensible to antibiotics and therefore are more difficult to eradicate. Linezolid and N-acetylcysteine (NAC), have demonstrated to be active against gram-positive microorganisms. Therefore and since linezolid and NAC have different modes of action, the main objective of this work was to investigate the single and synergistic effect of linezolid and NAC against S. epidermidis biofilms.

Methods

This work reports the in vitro effect of linezolid and NAC against S. epidermidis biofilms, treated with MIC (4 mg ml⁻¹) and 10×MIC of NAC, and MIC (1 μg ml⁻¹) and peak serum concentration (PS = 18 μg ml⁻¹) of linezolid alone and in combination. After exposure of S. epidermidis biofilms to linezolid and/or NAC for 24 h, several biofilm parameters were evaluated, namely the number of cultivable cells [colony forming unit (CFU) enumeration], total biofilm biomass and cellular activity.

Results

When tested alone, NAC at 10×MIC was the most effective agent against S. epidermidis biofilms. However, the combination linezolid (MIC) + NAC (10×MIC) showed a synergistic effect and was the most biocidal treatment tested, promoting a 5 log reduction in the number of biofilm viable cells.

Conclusion

This combination seems to be a potential candidate to combat infections caused by S. epidermidis biofilms, namely as a catheter lock solution therapy.     

Candida: epidemiología y factores de riesgo para especies no albicans

Introduction

Nosocomial fungal infections have increased significantly in the last decade. Candida detection in clinical specimens can mean either colonization or an infection which can be local (muguet) or invasive. Knowledge of the species helps in choosing the best treatment. The aims of this study were to determine the frequency and distribution of Candida species detected in clinical samples, to analyze the clinical characteristics of the involved population and to determine the risk factors for Candida non-albicans species.

Methods

Retrospective, observational. Period: 2006-2010. Inclusion criteria: all isolates of Candida in clinical specimens from patients hospitalized —at least 48 hours in a neurological center. We analyzed epidemiological characteristics, co morbidities, risk factors, factors associated with Candida non-albicans detection, antifungal treatment, development of adverse events and mortality.

Results

Candida spp. was isolated from 321 clinical specimens: 139 (43.3%) were C. albicans and 182 (56.7%) Candida non-albicans. The distribution of the sample was: urine 122 (Candida non-albicans 67.2%), airway 81, oropharynx 45 (C. albicans) and candidemia 40 (Candida non-albicans 75%). The most frequent co-morbidity was solid tumor (35.5%). The main risk factors were antibiotic therapy (85.5%), steroid therapy (61.7%) and in ICU at diagnosis (61.6%). The analysis of risk factors and the isolation of Candida non-albicans shows that chemotherapy, previous surgery, treatment with aminopenicillins, carbapenems and glycopeptides were statistically significant (P < .05). There is a trend in neutropenic patients (P = .055) and in ICU at diagnosis (P = .076). Overall survival was 71%.

Conclusions

Candida species distribution varies with the type of sample analyzed. Non-albicans species make up the majority of the isolates. The identification of the species involved per sample helps to optimize treatment. The high frequency of isolation of Candida in patients on steroids and antibiotics and admitted to ICU, is worth pointing out. Patients with previous surgery, treated with the aforementioned antibiotics or chemotherapy, could receive non-azole antifungals in the initial empirical treatment strategy.     

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.