sábado, 16 de noviembre de 2013

Neumonía asociada a ventilador/Ventilator-associated pneumonia

Agentes etiológicos de la neumonía asociada a ventilador y su patrón de resistencia-una amenaza para el tratamiento

Aetiological agents of ventilator-associated pneumonia and its resistance pattern - a threat for treatment.
Charles MP, Easow JM, Joseph NM, Ravishankar M, Kumar S, Sivaraman U.
Departments of Microbiology, Mahatma Gandhi Medical College and Research Institute, Pondicherry, India.
Australas Med J. 2013 Sep 30;6(9):430-4. doi: 10.4066/AMJ.2013.1710.
BACKGROUND:Ventilator-associated pneumonia (VAP) is a common type of nosocomial pneumonia encountered in intensive care units. There are several aetiological agents which make treatment challenging. Improper antibiotic treatment of ventilated patients may lead to the emergence of multidrug resistant (MDR) pathogens. METHOD: A prospective study was performed over a period of 20 months. Our study had two arms: the first, 'Incidence and risk factors of VAP in a tertiary care hospital' was the subject of an earlier publication; we therefore present the second investigative arm in this work. The aetiological agents of patients on mechanical ventilation (MV) were identified by standard bacteriological method. The susceptibility pattern was evaluated by Kirby-Bauer disc diffusion method. Extended spectrum beta lactamase (ESBL) testing was performed by combination disc method, and metallo-beta lactamase (MBL) testing was performed by EDTA disk synergy test (EDS). RESULTS: Late-onset VAP was associated with Pseudomonas aeruginosa, Klebsiella pneumoniae and Escherichia coli, while early-onset VAP was commonly caused by members of Enterobacteriaceae, Candida albicans and Staphylococcus aureus. 72.2 per cent of VAP patients had monomicrobial and 27.8 per cent had polymicrobial infection. Out of the 24 isolates obtained from patients with VAP, seven (29.2 per cent) were MDR pathogens. ESBL and MBL production was detected in 40 per cent and 20 per cent of Klebsiella pneumoniae isolated in our study. Around 50 per cent of isolates associated with late-onset VAP were MDR, while 22.2 per cent isolates obtained from patients with earlyonset VAP were MDR. CONCLUSION: VAP is a nosocomial pneumonia that is common among ventilated patients. The aetiological agents vary from common organisms to MDR pathogens that are difficult to treat. A proper knowledge of MDR pathogens and early isolation followed by prevention of prolonged antibiotic therapy can reduce the mortality of late onset VAP.
KEYWORDS: Ventilator associated pneumonia, aetiology, drug resistance

Perfil de microorganismos infecciosos que causan la neumonía asociada a la ventilación: Un estudio clínico de la unidad de cuidados intensivos de recursos limitados.

Profile of infective microorganisms causing ventilator-associated pneumonia: A clinical study from resource limited intensive care unit.
Thakuria B, Singh P, Agrawal S, Asthana V.
Department of Microbiology, Himalayan Institute of Medical Sciences, Dehradun, Uttarakhand, India.
J Anaesthesiol Clin Pharmacol. 2013 Jul;29(3):361-6. doi: 10.4103/0970-9185.117111.
BACKGROUND:Ventilator-associated pneumonia (VAP) is the most common cause of hospital acquired infection and death among patients admitted in ICU. Microorganisms responsible for VAP vary from place to place. Gram-negative bacteria (GNB) have emerged as a major group of pathogen causing VAP and over the years carbapenem group of antibiotics has emerged as one of the important antibiotics used in the critically ill patients. There have been reports of increased occurrence of infection by carbapenem-resistant bacteria in health care settings in recent times. AIM:The aim of the study was to assess the incidence of VAP, their microbiological profile with reference to carbapenemase producing GNB in the intensive care unit of a tertiary care hospital, their relation to initial emperical antibiotic therapy, sensitivity patterns, and outcome. MATERIALS AND METHODS:This prospective study was carried out over the period of 1 year (July 2010-June 2011) on 100 randomly selected patients above the age of 18 years admitted in the emergency/ICU and requiring intubation and mechanical ventilation for more than 72 hours. The diagnosis of VAP was established on the basis of clinical and radiological parameters as per Centre of Disease Centres (CDC) guidelines. A baseline sample was obtained after initial endotracheal intubation. Thereafter, the culture sent on the first day of occurrence of clinical sign of VAP. Culture was done on blood agar and MacConkey agar. All imipenem-resistant strains were further confirmed by Modified Hodge test and combined disc for confirmation of respective carbapenemase. RESULTS:Incidence of VAP was found to be 51%. GNB mainly Citrobacter 28 (52.83%) and Klebsiella pneumoniae 7 (13.21%), were the most commonly isolated pathogens. The prevalence of carbapenemase-producing GNB was alarmingly high 24/50 (48%). The entire carbapenemase producers showed high degree of cross resistance to antibiotics with some sensitivity to Polymyxin B (94 %) and Tigecycline (96%).
CONCLUSION: High incidence of VAP and the potential carbapenemase-producing GNB are real threat in our ICU. The emergence of microorganisms known for its inherent resistance among most of the common first-line antibiotics calls for a alarm in all upcoming tertiary care hospitals.

KEYWORDS:Carbapenemase, multidrug-resistant organisms, nosocomial pneumonia, ventilator-associated pneumonia



Dr. Juan C Flores-Carrillo
Anestesiología y Medicina del Dolor
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