Características clínicas y microbiológicas de las infecciones de piel y tejidos blandos por Staphylococcus aureus en niños de un hospital en Medellín durante los años 2013 a 2015 / Clinical and microbiological characteristics of skin and soft tissue infections caused by Staphylococcus aureus in children in a hospital in Medellin from 2013 to 2015

Resumen Introducción: El principal microorganismo implicado en las infecciones de piel y tejidos blandos (IPTB) es Staphylococcus aureus, con incremento en las cepas resistentes a meticilina en los últimos años. Objetivo: Identificar la frecuencia de S. aureus resistente a meticilina (SARM) en IPTB en niños que consultaron a un hospital de cuarto nivel en la ciudad de Medellín. Métodos: Estudio descriptivo, retrospectivo, a partir de la revisión de historias clínicas. Se incluyeron pacientes menores de 18 años con IPTB causadas por S. aureus que no cumplieran con criterios de enfermedad invasora. Resultados: La prevalencia de SARM en esta población fue de 31%. El principal diagnóstico fue absceso cutáneo (68%), seguido por infección de sitio quirúrgico (15%) y celulitis no purulenta (6%). Tenían alguna co-morbilidad 85% de los pacientes. Todos los aislados fueron sensibles a rifampicina y cotrimoxazol. Ocho por ciento de los aislados fueron resistentes a clindamicina. Se encontró mayor prevalencia de SARM en lactantes comparado con los mayores de 2 años (60 vs 23%, p = 0,0109). Conclusión: Ante la alta prevalencia de SARM en IPTB se recomienda incluir en el tratamiento empírico antimicrobianos con cobertura para estas cepas, principalmente para lactantes.

Background: Skin and soft tissue infections (SSTI) are very common in children and Staphylococcus aureus is the main agent, with an increase of methicillin resistant strains (MRSA) in recent years. Aim: To identify the frequency of MRSA in skin and soft tissue infections (SSTI) in children from a high complex hospital in Medellin, Colombia. Methods: This is a descriptive, retrospective study, information was obtained from medical records. We included patients younger than 18 years with SSTI due to S. aureus who did not meet criteria for invasive disease. Results: The prevalence of MRSA in this population was 31%. The main diagnosis was cutaneous abscess (68%), followed by surgical site infection (15%) and non-purulent cellulitis (6%). Eighty five percent of the patients had at least 1 comorbidity. All isolates were sensitive to rifampicin and cotrimoxazole and 8% of the isolates were resistant to clindamycin. There was a higher prevalence of MRSA in patients under 2 years compared to older (60 vs 23%, p = 0,0109). Conclusion: In view of the high prevalence of MRSA in SSTI, empirical treatment with adequate coverage for MRSA is recommended, especially for patients under 2 years of age.

Resistencia antimicrobiana y epidemiología molecular de aislamientos de Staphylococcus pseudintermedius de muestras clínicas de caninos / Antimicrobial resistance and molecular epidemiology of Staphylococcus pseudintermedius strains isolated from dog clinical samples

Se estudiaron 28 aislamientos obtenidos de muestras clínicas de perros e identificados por espectrometría de masas (MALDI-TOF) como Staphylococcus pseudintermedius; el objetivo fue evaluar la sensibilidad a los antimicrobianos por el método de difusión y establecer la relación clonal entre aislamientos por electroforesis en campo pulsado (PFGE). La resistencia a meticilina se evaluó mediante PCR por amplificación del gen mecA y se observó en 3/28 aislamientos (10,7 %). Quince aislamientos (53,6 %) presentaron resistencia a alguno de los antibióticos ensayados y 11 de ellos (39,3 %) presentaron resistencia múltiple (resistencia a 3 o más familias de antibióticos). Once aislamientos (39,3 %) presentaron resistencia a eritromicina, debido a la presencia de metilasa ribosomal ermB, y no se detectó resistencia inducible a clindamicina. Por PFGE se pudieron diferenciar 27 tipos clonales, lo cual demuestra gran diversidad clonal. Se destaca el hallazgo de aislamientos de S. pseudintermedius multirresistentes como una eventual problemática a considerar en el diagnóstico veterinario de laboratorio, el tratamiento de las infecciones caninas y el ámbito de la salud pública.

Twenty-eight strains isolated from dog clinical samples identified as Staphylococcus pseudintermedius by mass spectrometry (MALDI-TOF) were studied to assess antimicrobial susceptibility by the diffusion method and clonal relationship by pulsed field gel electrophoresis (PFGE). Methicillin resistance (3/28 isolates; 10,7 %) was evaluated by mecA PCR. Fifteen strains (53.6 %) were resistant to at least one of the antibiotics tested, and eleven of them (39.3 %) showed multiple resistance (3 or more antimicrobial families). Eleven isolates (39.3 %) were resistant to erythromycin due to the presence of ribosomal methylase ermB, whereas clindamycin inducible resistance was not detected. Twenty-seven (27) clonal types were differentiated by PFGE, suggesting high clonal diversity. We emphasize that the finding of multiresistant S. psedintermedius strains is an emerging problem to be considered in veterinary diagnostic laboratory treatment of canine infections and in public health settings.

Neumonía necrosante adquirida en la comunidad causada por Staphylococcus aureus resistente a meticilina ST30-SCCmecIVc-Spat019-PVL positivo en San Antonio de Areco, Argentina / Community-acquired necrotizing pneumonia caused by methicillin-resistant Staphylococcus aureus ST30-SCCmecIVc-spat019-PVL positive in San Antonio de Areco, Argentina

Community-acquired methicillin-resistant Staphylococcus aureus is the first cause of skin and soft tissue infections, but can also produce severe diseases such as bacteremia, osteomyelitis and necrotizing pneumonia. Some S. aureus lineages have been described in cases of necrotizing pneumonia worldwide, usually in young, previously healthy patients. In this work, we describe a fatal case of necrotizing pneumonia due to community-acquired methicillin-resistant S. aureus clone ST30-SCCmecIVc-spat019-PVL positive in an immunocompetent adult patient.

Staphylococcus aureus resistente a meticilina adquirido en la comunidad es la primera causa de infecciones de piel y partes blandas, aunque también puede producir infecciones graves, como bacteriemia, osteomielitis y neumonía necrotizante. Algunos linajes de S. aureus se han asociado a casos de neumonía necrotizante en el mundo, generalmente en pacientes jóvenes previamente sanos. En este trabajo comunicamos un caso fatal de neumonía necrotizante causado por el clon de S. aureus resistente a meticilina adquirido en la comunidad ST30-SCCmecIVc-spat019-LPV positivo, en un paciente adulto inmunocompetente

Aislamiento de Staphylococcus aureus meticilino resistente en abscesos de mama en una Maternidad Pública / Methicillin-resistant Staphylococcus aureus (MRSA) isolation in breast abscesses in a Public Maternity

La mastitis y los abscesos de mama representan un factor de riesgo para el abandono de la lactancia. Se incluyen dentro de las infecciones de piel y partes blandas y comparten los cambios epidemiológicos que llevan a replantear el tratamiento empírico inicial. Se estudiaron 137 casos de abscesos de mama desde enero de 2007 a diciembre de 2011. Se analizó incidencia, días postparto, factores de riesgo, datos microbiológicos y tratamiento antibiótico. Desde 2007a 2011 se observó un constante aumento de la incidencia de casos: 0.19 vs. 0.84% (p < 0.001). Días postparto de aparición del absceso 41.9 ± 35.8 días (Media ± DE), primiparidad 70.6%. Los factores de riesgo más frecuentemente encontrados fueron grietas del pezón e ingurgitación mamaria (95%). Staphylococcus aureus (SA) fue el responsable de 82.3 a 95.0% de los abscesos según los años; la resistencia a oxacilina de las cepas de SA superó el 60%. Las cepas aisladas de SA meticilino resistentes (SAMR) fueron sensibles a eritromicina clindamicina, gentamicina, rifampicina, ciprofloxacina y trimetroprima-sulfametoxasol en diferentes porcentajes según los años. Requirieron drenaje el 100% de los casos; en 60% el tratamiento empírico inicial fue inadecuado. Continuaron amamantando 90% de las madres. Estos datos enfatizan la necesidad de prevenir los factores de riesgo: grietas del pezón e ingurgitación mamaria. La modificación del tratamiento antibiótico inicial requiere el estudio bacteriológico de las infecciones de piel y partes blandas dado que la prevalencia de SAMR no es uniforme y varía en diferentes poblaciones y ubicaciones geográficas.

Mastitis and breast abscess in lactating women are risk factors for early breastfeeding cessation. This pathology is included in the group of skin and soft tissue infections. A descriptive study was performed with an advanced outlook. As of January 2007 through December 2011 a total of 137 breast abscesses were treated in our institution. We analyzed incidence, parity, postpartum days, risk factors, microbiological isolation and the adequacy of initial antibiotic treatment. In that period we observed a steady and significant increase in breast abscesses. Incidence from 0.19 to 0.84% in lactating women 2007 vs. 2011 p = 0.0001 IC 95% (-0.009; 0.003), 70.6% of them primiparous and a mean interval from delivery to breast abscess of 41.9 ± 35.8 days. The most frequent risk factors were sore nipples and breast engorgement. Staphylococcus aureus was isolated in 82.3 to 95.0%. Methicillin resistance was higher than 60%. These strains were susceptible to erythromycin, clindamycin, gentamicin, rifampicin, ciprofloxacin and trimethoprim-sulfamethoxazol. All the cases were surgically drained; the initial empirical treatment was inadequate in 60% of them, 90% of patients could maintain breast feeding after the procedure. In conclusion: these data emphasize the need to prevent risk factors associated to breast abscesses: sore nipples and breast engorgement. In order to determine the adequate antibiotic treatment, bacteriological studies are required at every collection because SAMR prevalence varies according to diverse populations and geographic location.

Staphylococcus coagulasa-negativa clínicamente significativos: Especies más frecuentes y factores de virulencia / Clinically significant coagulase-negative staphylococci: Most frequent species and virulence factors

Coagulase-negative staphylococci have emerged as responsible for a large number of infections. However, it is often difficult to assess its pathogenic role or to discard it as a contaminant. Aim: The goal of this study was to identify clinically significant coagulase-negative staphylococci to the species level and their virulence factors. Isolates came from patients consulting at the San Roque Laboratory from 2009 to 2011. Material and Methods: Species identification was performed by De Paulis et al simplified method. Production of biofilm, hemolysins, lipases, lecithinases and DNase were determined by conventional methods; methicillin-resistance by diffusion method and mecA and Panton-Valentine genes, by multiplex PCR. Results: Out of 64 isolates, 40.6% were S. epidermidis; 20.3%, S. haemolyticus, and 15.6%, S. lugdunensis. Biofilm production was detected in 73.1% of S. epidermidis, 53.8% of S. haemolyticus and 40% of S. lugdunensis. mecA gene was identified in 69.2% of S. epidermidis, 92.3% of S. haemolyticus and none of S. lugdunensis. 83% of mecA (+) S. epidermidis isolates were biofilm producers as compared to 50% of the mecA (-). Conclusion: The frequency of S. lugdunensis, the most virulent coagulase-negative staphylococci species, was relatively high. The main virulence factor in S. epidermidis was biofilm production, being higher in those resistant to methicillin.

Staphylococcus coagulasa-negativa ha emergido como responsable de un gran número de infecciones. No obstante, con frecuencia es difícil asegurar su rol patógeno o descartarlo como contaminante. Objetivo: Estudiar a nivel de especies Staphylococcus coagulasa-negativa clínicamente significativos y sus factores de virulencia, de aislados provenientes de pacientes del Laboratorio San Roque de Asunción, Paraguay entre los años 2009 y 2011. Material y Métodos: Para la identificación de especies fue utilizado el método simplificado de De Paulis y cols. La producción de biopelícula, hemolisinas, lipasas, lecitinasas, AD-Nasa, fue determinada por métodos convencionales; la resistencia a meticilina por difusión y los genes mecA y Panton-Valentine por RPC múltiple. Resultados: De 64 aislados, 40,6% correspondió a S. epidermidis, 20,3% S. haemolyticus y 15,6% S. lugdunensis. La producción de biopelícula fue detectada en S. epidermidis en 73,1%, S. haemolyticus 53,8% y S. lugdunensis 40%. El gen mecA fue identificado en 69,2% de S. epidermidis, 92,3% de S. haemolyticus y en ninguno de S. lugdunensis. El 83% de S. epidermidis mecA (+) fue productor de biopelícula en comparación a 50% de los mecA (-). Conclusión: La frecuencia de S. lugdunensis, una de las especies más virulentas de Staphylococcus coagulasa-negativa fue relativamente alta; y el principal factor de virulencia en S. epidermidis fue la producción de biopelícula, siendo mayor en los resistentes a meticilina.

Methicillin-resistant Staphylococcus lugdunensis carrying SCCmec type V misidentified as MRSA

Staphylococcus lugdunensis is a rare cause of severe infections and clinical manifestations are similar to those related to S. aureus infection. We describe a hospital-acquired bacteremia due to methicillin-resistant Staphylococcus lugdunensis, misidentified as methicillin-resistant S. aureus. The oxacillin MIC was 16 µg/mL and the mecA gene and SCCmec type V were determined by PCR. Although treatment had been appropriated, the patient died after rapid progressive respiratory failure and another nosocomial sepsis. It is important not only to identify S. lugdunensis in view of its clinical course, but also to determine its susceptibility to oxacillin by detecting the mecA gene or its product.

Laboratory detection methods for methicillin resistance in coagulase negative Staphylococcus isolated from ophthalmic infections

PURPOSE: To evaluate different methods of oxacillin susceptibility testing of ocular isolates, considering polymerase chain reaction (PCR) as the 'gold standard', and to compare the in vitro susceptibility to oxacillin with that of other antimicrobials used in ophthalmologic practice. METHODS: The Vitek gram-positive identification card was used to identify ocular coagulase negative Staphylococcus species. The presence of the mecA gene was determined by the polymerase chain reaction assay with a combination of two primer sets (mecA and 16S rRNA) in a single region. Results were analyzed and compared with other oxacillin susceptibility methods: PBP2a detection by rapid slide latex agglutination test (SLA); oxacillin E-test; the Vitek automated gram-positive susceptibility card (GPS-105); the oxacillin salt agar screening test (OSAS) at a concentration of 6.0, 1.0 and 0.75 æg oxacillin per ml and the cefoxitin disk diffusion test (CDD). Automated susceptibility was also determined to other antimicrobial agents (fluoroquinolones, penicillin G, amoxicillin-ampicillin, cefazolin, ampicillin-sulbactam, erythromycin, clindamycin, gentamicin, tetracycline, trimethoprim-sulfamethoxazole, vancomycin and rifampin. RESULTS: Of the 69 CoNS isolates tested, 71 percent were mecA-positive and 29 percent mecA-negative. All methods tested had a statistically significant agreement with polymerase chain reaction. There was a tendency of positive polymerase chain reaction predomination among the S. epidermidis isolates in comparison to non-epidermidis isolates, although this was not statistically significant (78.3 percent vs. 56.5 percent; chi2= 2.54; P= 0.11). The oxacillin salt agar screening test (0.75 æg oxacillin/ml) showed the best performance, with 100 percent sensitivity and negative predictive value; 95 percent specificity and 98 percent positive predictive value. Using the E-test, the mecA-positive isolates were statistically significantly more...

OBJETIVOS: Avaliar os diferentes métodos de suscetibilidade à oxacillina, em isolados oculares, considerando a reação em cadeia da polimerase (PCR) como "padrão-ouro" e comparar a suscetibilidade in vitro para outros antimicrobianos de uso oftalmológico. MÉTODOS: O sistema automatizado Vitek foi utilizado para identificar as diferentes espécies de Staphylococcus coagulase negativo (SCoN). A presença do gene mecA foi determinado pela reação em cadeia da polimerase com a combinação de 2 "primer" sets (mecA e 16S rRNA) em uma única região. Estes resultados foram analisados e comparados com outros métodos de suscetibilidade à oxacilina: detecção da proteína PBP2a pelo teste de aglutinação em látex (SLA); E-test oxacilina; o sistema automatizado Vitek (GPS-105); o teste de triagem em ágar (OSAS) com oxacilina nas concentrações de 6,0, 1,0 e 0,75 æg oxacilina por ml e o teste de disco difusão com cefoxitina (CDD). A suscetibilidade automatizada foi obtida para os seguintes agentes antimicrobianos: fluorquinolonas, penicilina G, amoxicilina-ampicilina, cefazolina, ampicilina-sulbactam, eritromicina, clindamicina, gentamicina, tetraciclina, sulfametoxazol-trimetoprima, vancomicina e rifampicina. RESULTADOS: Dos 69 Staphylococcus coagulase negativo testados, 71 por cento foram mecA-positivos e 29 por cento, mecA-negativos. Todos os métodos testados apresentaram concordância estatisticamente significante com a reação em cadeia da polimerase. Houve tendência à predominância da positividade da reação em cadeia da polimerase entre os S. epidermidis comparado aos não-epidermidis, embora sem significância estatistica (78,3 por cento vs. 56,5 por cento; chi2= 2,54; p=0,11). O teste de triagem em ágar (0,75 æg oxacilina/ml) apresentou a melhor performance com resultados de: 100 por cento de sensibilidade e valor preditivo negativo, 95 por cento de especificidade e 98 por cento de valor preditivo positivo. Os isolados mecA-positivos foram estatisticamente...

Colonização microbiana precoce de pacientes identificados por triagem neonatal para fibrose cística, com ênfase em Staphylococcus aureus / Early microbial colonization of cystic fibrosis patients identified by neonatal screening, with emphasis on Staphylococcus aureus

OBJETIVOS: Avaliar prospectivamente a colonização bacteriana de pacientes com fibrose cística identificados por triagem neonatal. Avaliar a suscetibilidade a antimicrobianos e caracterizar molecularmente as cepas de Staphylococcus aureus isoladas da orofaringe dos pacientes no período do estudo. MÉTODOS: Foram estudados 25 pacientes com fibrose cística, identificados por tripsina imunorreativa e com diagnóstico confirmado por duas ou mais provas de suor, atendidos regularmente no ambulatório de fibrose cística do Hospital de Clínicas da Universidade Federal do Paraná. Foram coletadas amostras de orofaringe com swab e cultivadas por métodos rotineiros; as colônias bacterianas foram identificadas fenotipicamente e testadas quanto à suscetibilidade a antimicrobianos. Os isolados de S. aureus foram submetidos a tipagem molecular por eletroforese em campo pulsado. RESULTADOS: De um total de 234 amostras de orofaringe, S. aureus foi isolado em maior número (76 por cento dos pacientes, 42 por cento das amostras), seguido de Pseudomonas aeruginosa (36 por cento dos pacientes, 16 por cento das amostras) e Haemophilus spp. (76 por cento dos pacientes; 19 por cento das amostras). Dos 19 pacientes colonizados com S. aureus, foram obtidos 73 isolados, 18 oxacilina-resistentes (24,6 por cento), isolados de dois pacientes, com perfis eletroforéticos idênticos ao do clone brasileiro. Os demais isolados oxacilina-sensíveis distribuíram-se entre 18 perfis eletroforéticos distintos. CONCLUSÃO: Observou-se uma maior prevalência de S. aureus, com isolamento mais precoce em relação aos outros patógenos pesquisados. Os isolados multissensíveis distribuíram-se em clones distintos, caracterizando a não transmissibilidade entre as cepas comunitárias. Os S. aureus resistentes a oxacilina isolados apresentaram perfis eletroforéticos idênticos, provavelmente adquiridos no ambiente hospitalar. P. aeruginosa foi pouco freqüente na população estudada.

OBJECTIVES: To assess bacterial colonization prospectively in patients with cystic fibrosis identified by neonatal screening. To assess susceptibility to antimicrobials and to perform the molecular typing of Staphylococcus aureus strains isolated from the oropharynx of patients during the study. METHODS: Twenty-five cystic fibrosis patients receiving regular treatment at the Cystic Fibrosis Outpatient Clinic of Hospital de Clínicas of Universidade Federal do Paraná Brazil, were included in the study. All patients were identified by trypsin-like immunoreactivity and their diagnosis was confirmed by two or more sweat tests. Oropharyngeal swabs were collected and cultured according to routine methods; bacterial colonies were phenotypically identified and their susceptibility to antimicrobials was tested. S. aureus isolates were submitted to molecular typing using pulsed-field gel electrophoresis. RESULTS: Out of 234 oropharyngeal swabs, S. aureus was the most frequently isolated strain (76 percent of patients, 42 percent of swabs), followed by Pseudomonas aeruginosa (36 percent of patients, 16 percent of swabs) and Haemophilus spp. (76 percent of patients; 19 percent of swabs). Seventy-three isolates were obtained from 19 patients colonized with S. aureus, of which 18 were oxacillin-resistant (24.6 percent), isolated from two patients, with the same electrophoretic profiles as that of the Brazilian clone. The remaining oxacillin-sensitive isolates were distributed into 18 electrophoretic profiles. CONCLUSION: There was higher prevalence of S. aureus, with earlier isolation than other pathogens. Multi-sensitive isolates were distributed into different clones, characterizing non-transmissibility among community-acquired strains. The isolated oxacillin-resistant S. aureus showed identical electrophoretic profiles, probably acquired in hospital. P. aeruginosa was not so frequent in the studied population.

Enfermedad invasora por Staphylococcus aureus meticilino: resistente adquirida en la comunidad / Community-acquired methicillin-resistant Staphylococcus aureus disseminated disease

Se presenta un caso de enfermedad invasora por Staphylococcus aureus meticilino resistente (SAMR)adquirido en la comunidad (SAMR-c). Paciente varón de 21 años, previamente sano, que consultó por nódulos subcutáneos compatibles con gomas. La ultrasonografía reveló múltiples abscesos subcutáneos e imágenes consistentes con piomiositis, además de derrame pleural y pericárdico. En el cultivo del material purulentoobtenido por punción-aspiración con aguja fina de las lesiones se aisló S. aureus. El antibiograma por difusiónmostró resistencia a cefalotina, eritromicina y clindamicina, y sensibilidad a trimetroprima-sulfametoxazol, ciprofloxacina y rifampicina. La meticilino resistencia se confirmó por aglutinación con partículas de látex sensibilizadas con anticuerpos monoclonales dirigidos contra la proteína ligadora de penicilina 2A. El paciente fue tratado con ciprofloxacina y rifampicina durante cuatro semanas, con evolución favorable. La frecuencia de infecciones por SAMR-c está en aumento, observándose en personas sin factores de riesgo aparentes. Esto llevaría a fracaso en el tratamiento empírico para infecciones de la comunidad en los que se presume etiología estafilocócica

A 21 year old man, previously healthy, presented with subcutaneous nodes consistent with gummas. Ultrasonography disclosed multiple subcutaneous abscesses and images suitable with piomiositis, pleural and pericardium effusion. A puncture-aspirate with fine-needle was performed and produced purulent material, with isolate of Staphylococcus aureus. Antimicrobial susceptibility testing by disk diffusion showed resistant to cefalotin, erythromycin and clindamycin, and susceptibility to trimethoprim-sulfamethoxazole, ciprofloxacin and rifampicin. Methicilin-resistance was confirmed by Staphyslide agglutination testing (Biomérieux). The patient was treatedwith ciprofloxacin and rifampicin during four weeks, with a good clinical response. The frequency of CA-MRSAinfections is increasing, and these are reported in patients without identified predisposing risks leading to failureon empiric therapy for community infections presumed to be due to staphylococcal agent

Evaluation of the humoral immune response in BALB/c mice immunized with a naked DNA vaccine anti-methicillin-resistant Staphylococcus aureus

Methicillin-resistant Staphylococcus aureus (MRSA) is the major pathogen involved in nosocomial infections, leading to high rates of morbidity and mortality in hospitals worldwide. The methicillin resistance occurs due to the presence of an additional penicillin-binding protein, PBP2a, which has low affinity for b-lactam antibiotics. In the past few years, vancomycin has been the only antibiotic option for treatment of infections caused by multiresistant MRSA; however, reports of vancomycin-resistant strains have generated great concerns regarding the treatment to overcome these infections. In the present study, we report preliminary results regarding the humoral immune response generated in BALB/c mice by two different doses of naked DNA vaccine containing an internal region, comprising the serine-protease domain, of the PBP2a of MRSA. The immunization procedure consisted of four immunizations given intramuscularly within 15-day intervals. Blood was collect weekly and anti-PBP2a-specific antibodies were screened by ELISA. BALB/c mice immunized with DNA vaccine anti-PBP2a have shown higher antibody titers mainly after the fourth immunization, and intriguingly, no correlation between the humoral immune response and DNA dose was observed. Our results suggest that the DNA vaccine anti-PBP2a induced an immune response by production of specific antibodies anti-MRSA in a non-dose-dependent manner, and it could represent a new and valuable approach to produce specific antibodies for passive immunization to overcome MRSA infections.

Cost-effectiveness of linezolid versus vancomycin in mechanical ventilation-associated nosocomial pneumonia caused by methicillin-resistant staphylococcus aureus

Linezolid, an oxazolidinone-class antimicrobial agent, is a new drug; its use has frequently been questioned due to its high price. However, recent trials have demonstrated that the use of linezolid in mechanical ventilation-associated nosocomial pneumonia caused by methicillin-resistant Staphylococcus aureus (VAP-MRSA) may be justified due to its improved efficacy compared to vancomycin. Price and cost have different magnitudes, and clinical efficacy should always be considered in the decision-making process. Our objective was to determine whether linezolid treatment was more cost-effective than vancomycin for treating VAP-MRSA. METHODOLOGY: Elaboration of an economic model from a metanalysis of previous clinical trials comparing both drugs, through a cost-effectiveness analysis. Costs of the treatments were calculated using Brazilian parameters and were compared to the results obtained in the metanalysis. In order to compare the results with real life conditions, costs were calculated for both name brand and for generic vancomycin. RESULTS: The cost (May/2004) per unit (vial, ampoule or bag) was R$ 47.73 for the name-brand vancomycin, R$ 14.45 for generic vancomycin and R$ 214.04 for linezolid. Linezolid's efficacy in VAP-MRSA according to the metanalysis was 62.2 percent and vancomycin's efficacy was 21.2 percent. The total cost per cured patient was R$ 13,231.65 for the name-brand vancomycin, R$ 11,277.59 for generic vancomycin and R$ 7,764.72 for linezolid. CONCLUSION: Despite the higher price per unit, linezolid was more cost-effective than vancomycin.

In vitro activity of sodium-benzoate against isolates of methicillin-resistant Staphylococcus aureus / Actividad In Vitro del Benzoato de Sodio contra los Aislados de Staphylococcus aureus Resistentes a la Meticilina

BACKGROUND: Worldwide, methicillin-resistant Staphylococcus aureus (MRSA) rates have increased dramatically during the last decades. Sodium benzoate (SB) is a chemical substance that is used for preparing food and drinks and in the treatment of some metabolic (urea cycle disorders and hepatic coma) diseases. No studies were found which focussed on the effects of SB in MRSA infections. The aim was to determine in vitro activity of sodium benzoate against MRSA clinical isolates. METHODS: In this study, MIC for SB in 36 MRSA and 29 methicillin-sensitive Staphylococcus aureus (MSSA) isolates were determined by a broth microdilution method recommended by the National Committee for Clinical Laboratory Standards. RESULTS: The MIC at which all of the MRSA and MSSA strains were inhibited was at 32 microg/ml and higher concentrations. CONCLUSION: Sodium benzoate showed good in vitro activity against clinically relevant MRSA and MSSA isolates. It is suggested in this study that this cheap substance, which has been used for systemic and local treatment of infection in humans, may be used alternatively for the treatment of MRSA infections. However, it is clear that more comprehensive and in vivo studies are needed to further elucidate the activity of SB against MRSA infections

Antecedentes: A nivel mundial, los índices de Staphylococcus aureus resistente a la meticilina (SARM) han aumentado dramáticamente durante las últimas décadas. El benzoato de sodio (BS) es una sustancia química que se usa ampliamente en la preparación de comidas y bebidas, y en el tratamiento de algunas enfermedades metabólicas (trastornos del ciclo de la urea y coma hepático). No encontramos ningún estudio dedicado específicamente a los efectos del BS en las infecciones por SARM. Nos trazamos como objetivo determinar la actividad in vitro del benzoato de sodio contra los aislados clínicos de SARM. Métodos: En este estudio, se determinaron la concentración mínima inhibitoria (CMI) para el BS en 36 SARM y 29 aislados de Staphylococcus aureus sensible a la meticilina (SASM), mediante un método de microdilución en caldo, recomendado por el Comité Nacional para las Normas de Laboratorios Clínicos. Resultados: La CMI a la que se inhibieron todas las cepas de SARM y SASM fue de 32 µg/ml y concentraciones más altas. Conclusión: El benzoato de sodio demostró ser bueno en la actividad in vitro contra los aislados de SARM y SASM clínicamente relevantes. Sugerimos que esta sustancia económica, que se ha usado para el tratamiento sistémico y local de infecciones en los seres humanos, puede usarse alternativamente para el tratamiento de infecciones por SARM. Sin embargo, está claro que se requieren estudios in vivo y más exhaustivos, que contribuyan a un entendimiento aún más claro de la actividad del BS contra las infecciones por SARM.

Prevalence of methicillin-resistant Staphylococcus aureus (MRSA) among patients visiting the emergency room at a tertiary hospital in Brazil

We surveyed patients seen at the emergency room at a tertiary hospital in Brazil from August to November 1997. All patients' (n = 600) anterior nares were cultured for MRSA; the results were confirmed by oxacillin disk diffusion methods and by detection of the mecA gene with PCR. Bacteria were found in 93.3 percent (560) of the patients and MRSA in 0.7 percent (n = 4). One patient had community-acquired MRSA. We concluded that MRSA is uncommon among patients visiting the emergency room. The presence of community-acquired MRSA can lead to serious medical and epidemiological issues, although initial clinical presentation may not differ from that of infections with other staphylococci. The empirical use of vancomycin for suspected community-acquired infections is seldom warranted.