Infección por Staphylococcus lugdunensis: descripción de 44 casos / Staphylococcus lugdunensis infection: report of 44 cases

INTRODUCCIÓN: Staphylococcus lugdunensis, es un estafilococo coagulasa negativa (SCN) con características de virulencia y de sensibilidad antimicrobiana que lo hacen más parecido a Staphylococcus aureus que a otros SCN. OBJETIVOS: Conocer las características clínicomicrobiológicas de los aislados de S. lugdunensis identificados en nuestra institución. MATERIAL Y MÉTODOS: Se realizó un estudio retrospectivo de los aislados de S. lugdunensis entre los años 2017 y 2019 en el Servicio de Microbiología del Hospital Universitario San Jorge de Huesca (España). Se revisaron las historias clínicas correspondientes a los pacientes con aislamiento de S. lugdunensis, considerándose las siguientes variables: edad, sexo, tipo de muestra, servicio de procedencia y enfermedad de base. La identificación bacteriana se realizó con MALDI-TOF VITEK MS (BioMérieux, Francia). Así mismo, se estudió su patrón de susceptibilidad antimicrobiana in vitro mediante microdilución en placa. RESULTADOS: Se obtuvieron 44 aislados de S. lugdunensis: 12 procedían de heridas, 10 fueron abscesos, 8 úlceras, 7 orinas, 4 frotis cutáneos, 2 exudados óticos, y 1 exudado vaginal. En relación con la enfermedad de base destacaron cinco pacientes con procesos tumorales y diez con diabetes mellitus. En 17 pacientes existían antecedentes de cirugía o traumatismo reciente. La mayoría de las cepas fueron sensibles a los antimicrobianos estudiados. En 19 de ellas se observó producción de β-lactamasa, dos fueron resistentes a macrólidos y tres a clindamicina. Todas las cepas fueron sensibles a oxacilina, gentamicina y cotrimoxazol. CONCLUSIONES: Aunque S. lugdunensis mantiene una buena sensibilidad a la mayoría de los antimicrobianos, su tendencia a producir abscesos y que exprese factores de virulencia más parecido a S. aureus que a otros SCN, hace necesaria una correcta identificación en el laboratorio con el fin de que su incidencia no quede subestimada.

BACKGROUND: Staphylococcus lugdunensis is a coagulase-negative staphylococcus (CNS) with virulence and antibiotic sensitivity characteristics which makes it more similar to Staphylococcus aureus than other CNS. AIM: To know the microbiological and clinical characteristics of S. lugdunensis isolates identified from our health sector. METHODS: A retrospective study of S. lugdunensis isolates was carried out between 2017 and 2019 in the Microbiology Service of the San Jorge University Hospital in Huesca (Spain). The clinical records of patients with S. lugdunensis isolation were reviewed, considering the following factors: age, sex, sample type, service and underlying disease. Bacterial identification was performed using MALDI-TOF VITEK MS (BioMérieux, France). The pattern of antibiotic susceptibility was studied by means of plate microdilution. RESULTS: 44 isolates of S. lugdunensis were obtained: 12 corresponded to wounds, 10 were abscesses, 8 ulcers, 7 urine samples, 4 skin smears, 2 otic exudates, and 1 vaginal exudate. Regarding the underlying disease, five patients had a tumor processes and ten had diabetes mellitus. In 17 patients there was a history of recent surgery or trauma. Most of the strains were susceptible to the antibiotics studied. Production of beta-lactamase was observed in 19 of them, two were resistant to macrolides and three to clindamycin. None of the isolates were resistant to oxacillin, gentamicin or cotrimoxazole. CONCLUSIONS: Although S. lugdunensis maintains a good sensitivity to most antibiotics, its tendency to produce abscesses and that it expresses virulence factors more similar to S. aureus than to other CNS requires a correct identification in the laboratory so that its incidence is not underestimated.

Bacteriemias por staphylococcus aureus: factores de riesgo asociados a la resistencia a meticilina / Bacteriemias caused by staphylococcus aureus: risk factors associated to methicillin resistance

INTRODUCCION: el objetivo del trabajo ha sido identificar los factores de riesgo que podrían favorecer la aparición de resistencia a meticilina en aislamientos de Staphylococcus aureus y aquellos que influirían en la mortalidad por las bacteriemias producidas por este patógeno. METODOS: se realizó un estudio observacional de casos y controles en los 57 pacientes diagnosticados de bacteriemia por Staphylococcus aureus en el Hospital de Barbastro. Para el análisis se utilizaron los test estadísticos de Chi cuadrado de Pearson, test de Fisher y regresión logística múltiple. RESULTADOS: del total de bacteriemias, 63,15% correspondieron a Staphylococcus aureus sensible a meticilina y 36,84% a Staphylococcus aureus resistente a meticilina. Se asociaron a resistencia a meticilina, la adquisición nosocomial de la infección, el uso previo de antibióticos y la edad mayor de 65 años. La mortalidad de los casos de bacteriemia por SARM y SAMS fue respectivamente del 28,57% y del 36,11%, siendo estas diferencias estadísticamente no significativas. Todos los aislamientos fueron sensibles in vitro a vancomicina. CONCLUSIONES: en nuestro sector sanitario, las estrategias más efectivas para disminuir la incidencia de bacteriemias por SARM serían el control y uso adecuado de antimicrobianos y la aplicación de programas de prevención de infecciones nosocomiales. En los pacientes con bacteriemia por Staphylococcus aureus, la resistencia a meticilina no se asocia a más mortalidad.

INTRODUCTION: the objective of this work has been to identify the risk factors that could favor the appearance of methicillin resistance in isolates of Staphylococcus aureus (SA) and those that would influence mortality due to bacteremia produced by this pathogen. METHODS: an observational case-control study was carried out in 57 patients diagnosed with bacteremia by SA at the Barbastro's Hospital. Pearson Chi square statistical test, Fisher test and multiple logistic regression were used for the analysis. RESULTS: of the total Bacteriemias, 63.15% corresponded to methicillin-sensitive Staphylococcus aureus (MSSA) and 36.84% to methicillin-resistant Staphylococcus aureus (MRSA). Nosocomial acquisition of the infection, previous use of antibiotics and the age over 65 years, were associated with methicillin resistance. The mortality of cases of MRSA and SAMS bacteremia was 28.57% and 36.1 1% respectively, these differences being statistically not significant. All isolates were sensitive in vitro to vancomycin. CONCLUSIONS: in our health sector, the most effective strategies to reduce the incidence of MRSA bacteremia would be the control and proper use of antimicrobials and the application of nosocomial infection prevention programs. Patients with SA bacteremia, are not associated with more mortality caused by MRSA.

Clinical significance, antimicrobial susceptibility and molecular identification of Nocardia species isolated from children with cystic fibrosis

ABSTRACT Nocardia is an opportunistic pathogen that causes respiratory infections in immunocompromised patients. The aim of this study was to analyze the epidemiology, clinical significance and antimicrobial susceptibility of Nocardia species isolated from eight children with cystic fibrosis. The isolated species were identified as Nocardia farcinica, Nocardia transvalensis, Nocardia pneumoniae, Nocardia veterana and Nocardia wallacei. N. farcinica was isolated in three patients and all of them presented lung affectation with a chronic colonization and pneumonia. N. farcinica showed resistance against gentamicin, tobramycin, cefotaxime, but was susceptible to trimethoprim-sulfamethoxazole and amikacin. N. transvalensis, which was isolated from two patients, showed an association with chronic colonization. N. transvalensis was resistant to tobramycin and amikacin, but susceptible to ciprofloxacin, trimethoprim-sulfamethoxazole and cefotaxime. N. veterana, N. pneumoniae and N. wallacei were isolated from three different patients and appeared in transitory lung colonization. N. veterana and N. pneumoniae were susceptible to imipenem, trimethoprim-sulfamethoxazole, amikacin, tobramycin, and cefotaxime. N. wallacei was resistant to amikacin, tobramycin, imipenem, and trimethoprim-sulfamethoxazole and susceptible to ciprofloxacin and cefotaxime. All the isolates were identified up to species level by 16S rRNA gene sequencing. The presence of Nocardia in the sputum of patients with cystic fibrosis is not always an indication of an active infection; therefore, the need for a treatment should be evaluated on an individual basis. The detection of multidrug-resistant species needs molecular identification and susceptibility testing, and should be performed for all Nocardia infections.