Emergence of high-level resistance to gentamicin and streptomycin in Streptococcus agalactiae in Buenos Aires, Argentina                                
 

HUGO EDGARDO VILLAR, MÓNICA BEATRIZ JUGO             

Introduction. Streptococcus agalactiae has become recognized as a cause of serious illness in newborns, pregnant women, and adults with chronic medical conditions. Optimal antimicrobial therapy for serious infections requires the use of synergistic combinations of a cell wall-active agent, such as a penicillin, with an aminoglycoside, which results in bactericidal activity against this organism. The synergistic effect is eliminated by the acquisition of high-level resistance (HLR) to aminoglycosides. The aim of our study was to determine the prevalence of HLR to gentamicin (GEN) and streptomycin (EST). The ability to detect HLR using a standard agar screen plate and high-content discs was investigated.
Methods. This study was conducted with 141 strains of S. agalactiae isolated from vaginal and rectal swabs of pregnant women at term. Minimum inhibitory concentrations (MICs) to GEN and STR were determined by the E-test method. Disks of GEN (120 μg) and STR (300 μg) were used to detect HLR. Agar screening plates were performed with GEN 100 mg/L, GEN 500 mg/L and STR 2000 mg/L.
Results. The HLR to GEN and STR was detected in 13.5% and 16.3% of the isolates respectively. Among 141 strains, 7.8% were simultaneously resistant to GEN and STR. With 120-μg GEN and 300-μg STR disks, strains for which MICs were ≥512 mg/L and ≥1024 mg/L had no zones of inhibition. Isolates with inhibitory zones for GEN and STR of ≥13 mm showed a MICs ≤64 mg/L and ≤512 mg/L. All the screening plates were negative for these isolates. HLR to aminoglycosides was associated (83.9%) with resistance to erythromycin and/or clindamycin.
Conclusions. This study highlights the emergence of strains with HLR to aminoglycosides. The disk-agar diffusion test performed with high-content aminoglycoside disks and screening plates can provide laboratories with a convenient and reliable method for detecting S. agalactiae isolates that are resistant to aminoglycoside-betalactam synergy.

Rev Esp Quimioter 2013:26(2):112-115 [pdf]

Physicians with access to point-of-care tests significantly reduce the antibiotic prescription for common cold                                 
 

C. LLOR, S. HERNÁNDEZ, J. M. COTS, L. BJERRUM, B. GONZÁLEZ, G. GARCÍA, J. D. ALCÁNTARA, G.  GUERRA, M. CID, M. GÓMEZ, J. ORTEGA, C. PÉREZ, J. ARRANZ, M. J. MONEDERO, J. PAREDES, V. PINEDA, GRUPO DE TRABAJO HAPPY AUDIT ESPAÑA               

Objective. This study was aimed at evaluating the effect of two levels of intervention on the antibiotic prescribing in patients with common cold.
Methods. Before and after audit-based study carried out in primary healthcare centres in Spain. General practitioners registered all the episodes of common cold during 15 working days in January and February in 2008 (preintervention). Two types of intervention were considered: full intervention, consisting in individual feedback based on results from the first registry, courses in rational antibiotic prescribing, guidelines, patient information leaflets, workshops on rapid tests –rapid antigen detection and C-reactive protein tests– and provision of these tests in the surgeries; and partial intervention, consisting of all the above intervention except for the workshop and they did not have access to rapid tests. The same registry was repeated in 2009 (postintervention). In addition, new physicians filled out only the registry in 2009 (control group).
Results. 210 physicians underwent the full intervention, 71 the partial intervention and 59 were assigned to the control group. The 340 doctors prescribed antibiotics in 274 episodes of a total of 12,373 cases registered (2.2%).The greatest percentage of antibiotic prescription was found in the control group (4.6%). The partial intervention increased the antibiotic prescription percentage from 1.1% to 2.7% while only doctors who underwent the complete intervention lead to a significant reduction of antibiotics prescribed, from 2.9% before to 0.7% after the intervention (p<0.001).
Conclusion. Only physicians with access to rapid tests significantly reduced antibiotic prescription in patients with common cold.

Rev Esp Quimioter 2013:26(1):12-20 [pdf]

Staphylococcus aureus infections and factors associated with resistance to methicillin in a hospital emergency department 

JUAN GONZÁLEZ-CASTILLO, CATERINA CENCI, ESTHER RODRIGUEZ-ADRADA, FRANCISCO JAVIER CANDEL, FERNANDO DE LA TORRE-MISIEGO, CRISTINA FERNÁNDEZ, FRANCISCO JAVIER MARTÍN-SÁNCHEZ             

Objective. Assessment of the characteristics of patients with Staphylococcus aureus (SA) infections, and factors associated with resistance to methicillin in a hospital emergency department (ED) in Spain.
Materials and Methods. All adult patients admitted between January 2007 and December 2010 with a SA infection confirmed by a positive culture in a sample obtained in the hospital emergency department were selected for enrolment. Epidemiological, clinical, therapeutic and microbiological variables were retrospectively collected from the patients’ medical charts. The variable assessed within the primary outcome of the study was the isolation of methicillin resistant Staphylococcus aureus (MRSA). For the purpose of the analysis, the sample was divided in terms of the presence or not of the resistance to methicillin and a logistic regression analysis was performed to identify the factors associated with isolation and empirical antibiotic coverage of MRSA.
Results. A total of 207 patients with a confirmed SA infection were included in the study analysis, with a mean age of 64.7 (SD 20) years. MRSA was isolated in a total of 63 (30.4%) patients, and a linear incremental trend was observed over the course of the study (p=0,047). MRSA was empirically covered in the emergency department on an average rate of one in three patients. Independent factors associated with the isolation of MRSA were: age above 65 years [OR 2.97 (95% CI 1.24 to 7.1), P = 0.014], severe baseline functional dependence [OR 2.41 (95 % 1.02 to 5.69), P = 0.045], chronic obstructive pulmonary disease [OR 4.83 (95% CI 1.88 to 12.42), P = 0.001], history of antibiotic treatment within the previous 2 months [OR 4.94 (95% CI 2.27 to 10.76), P <0.001] and a confirmed urinary infection [OR 5.98 (95% CI 1.65 to 21.69) p = 0.007]. Independent factors associated with empiric coverage of MRSA in the ED were history of antibiotic treatment within the previous 2 months [OR 3.88 (95% CI 1.76 to 8.57), P <0.001] and the presence of a catheter device [OR 6.28 (95% CI 1.64 to 24.07), P = 0.007].
Conclusions. Resistance to methicillin appears to be increasingly frequent in patients infected with SA admitted in our emergency department and there appears to be a need for a more optimal empiric antibiotic treatment in these patients.

Rev Esp Quimioter 2013:26(4):337-345 [pdf]

Bacteraemia at a second level hospital: epidemiological study, analysis of pronostic factors associated to mortality and economic cost estimation                                
 

JOSÉ JOAQUÍN HERNÁNDEZ-ROCA, ELISA GARCÍA-VÁZQUEZ, ALICIA HERNÁNDEZ, MANUEL CANTERAS, JOSÉ ANTONIO HERRERO, EVA CASCALES, ENRIQUE MENÉ-FENOR, JOAQUÍN GÓMEZ-GÓMEZ
             

Introduction. Bacteraemia (B) accounts for a considerable proportion (0.36%) of all hospital admissions due to infections diseases and it is associated to increased hospital costs. The aim of this study is to describe a cohort of patients with bacteraemia  at a second level hospital, to analyze factors associated to mortality and its economical impact during hospital admission.
Patients and Methods. Observational study of a cohort of adult patients with bacteraemia admitted at a second level hospital during 2010. Data collection from clinical records has been done according to a standard protocol: epidemiological and clinical variables and factors associated to mortality were analysed. Total economical cost per patient was estimated.
Results. 148 patients were included: 80 community B (55.4%), 23 health care associated B (15.5%) and 45 nosocomial B (28.5%). The incidence was 9 cases 10.000 persons/year. Mean age was 69 years and the global mortality was 24%. In bivariate analysis smoking, diabetes mellitus, McCabe Jackson score type I-II, Pitt Index ≥ 3, APACHE ≥ 20, Glasgow ≤9, shock, respiratory distress, invasive procedures, nosocomial bacteraemia and inadequate empiric or definitive antibiotic treatment were associated to mortality (p<0.05). Factors associated to mortality in multivariate analysis included McCabe Jackson score type I-II (OR 4.95; 95% CI 1.095-22.38), haemodialysis during acute stage (OR 7.8; 95% CI 2.214-27.773) and inadequate empiric antibiotic treatment (OR 7.68; 95% CI 19.82-29.77). Admission economic cost per patient was 9,459€ for community acquired bacteriemia, 5,656€ for health care associated bacteraemia and 41,680€ for nosocomial bacteraemia.
Conclusions. Comorbidity, inadequate empiric antibiotic treatment and haemodialysis during acute phase are statistically significantly in our cohort of patients with bacteraemia.

Rev Esp Quimioter 2013:26(2):119-127 [pdf]

Pyelonephritis in pregnancy. How adequate is empirical treatment?                                  
 

A. ARTERO, J. ALBEROLA, J.M. EIROS,  J.M. NOGUEIRA, A. CANO                 

Objective. To ascertain the adequacy of empirical antimicrobial treatment in pregnant women with acute pyelonephritis.
Material and methods. We have conducted a retrospective observational study of women admitted to the hospital with acute pyelonephritis between May 2004 and April 2011.
Patients were included if the results of urine cultures and susceptibility testing to antibiotics were available. Epidemiological, clinical, therapeutical and outcome variables were collected from chart review. We considered inappropriate empirical antimicrobial treatment (IEAT) as the occurrence of microorganism that were not effectively treated at the time when the causative microorganism and its antibiotic susceptibility were known.
Results. Fifty women with appropriate microbiological data from a total of 93 cases of acute pyelonephritis were included in the study. The women’s mean age was 26.4 years, and 58% were nulliparous. Pyelonephritis was developed in the 2nd and 3rd trimester in 88% of cases. Previous urinary tract infections were recorded in 34%. Escherichia coli was the most frequent microorganism (70%). The proportion of patients who received IEAT was 10%. Amoxicillin-clavulanate and cepahlosporines were the most predominant antibiotics used, with a proportion of IEAT of 10.3% and 5.9%, respectively.
Conclusions. Pregnant women with pyelonephritis received IEAT in a small but significant number of cases. Amoxicillin-clavulante and cephalosporines were adequate in most cases. More studies are needed to define the clinical impact of IEAT on prognosis.

 

Rev Esp Quimioter 2013:26(1):30-33 [pdf]