The widespread use of tracheal intubation and mechanical ventilation to support the critically ill patients increases the risk of development of tracheobronchitis and bronchopneumonia. This cross-sectional study was conducted with an aim to isolate and identify bacterial pathogens from tracheal aspirates producing extended-spectrum β-lactamase (ESBL), AmpC β-lactamase, and metallo-β-lactamase (MBL) from August 2011 to April 2012 at National Institute of Neurological and Allied Sciences (NINAS), Kathmandu, Nepal. ESBL was detected by combined disk assay using cefotaxime and cefotaxime with clavulanate, AmpC β-lactamase by inhibitor-based method using cefoxitin and phenylboronic acid, and MBL by Imipenem-EDTA combined disk method. 167 bacterial strains were isolated from 187 samples and majority of them were Acinetobacter spp. followed by Klebsiella pneumoniae with 32.9% and 25.1%, respectively. 68.8% of isolates were multidrug resistant (MDR) and Acinetobacter spp. constituted 85.4%. ESBL, AmpC β-lactamase, and MBL were detected in 35 (25%), 51 (37.2%), and 11 (36.7%) isolates, respectively. Pseudomonas spp. (42.8%) were the predominant ESBL producer while Acinetobacter spp. were the major AmpC β-lactamase producer (43.1%) and MBL producer (54.5%). 1. Introduction Tracheostomy is a surgical procedure that creates an opening directly into the trachea to ventilate and aspirate the patient in critical care setting . The incidence of ventilator-associated pneumonia (VAP) ranges from 10 to 25% of all intensive care unit (ICU) patients resulting in high mortality rate of 22–71%, which is 6–21 times higher in intubated patients . The tracheostomized patients are colonized or infected with bacteria either endogenously or exogenously. Exogenous bacteria include Pseudomonas spp., Acinetobacter spp., methicillin-resistant Staphylococcus aureus (MRSA), and members of Enterobacteriaceae and endogenous bacteria include Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. These bacteria are usually resistant to multiple antibiotics and cause either tracheobronchitis or bronchopneumonia . Risk factors for colonization or infection with multidrug-resistant bacterial species include prolonged length of hospital stay, exposure to an ICU, receipt of mechanical ventilation, colonization pressure, exposure to broad-spectrum antimicrobial agents, recent surgery, invasive procedures, and underlying severity of illness [4, 5]. β-Lactamases are the commonest cause of bacterial resistance to β-lactam antimicrobial agents, which are used in the
P. Pignatti, A. Balestrino, C. Herr et al., “Tracheostomy and related host-patogen interaction are associated with airway inflammation as characterized by tracheal aspirate analysis,” Respiratory Medicine, vol. 103, no. 2, pp. 201–208, 2009.
E. G. Playford, J. C. Craig, and J. R. Iredell, “Carbapenem-resistant Acinetobacter baumannii in intensive care unit patients: risk factors for acquisition, infection and their consequences,” Journal of Hospital Infection, vol. 65, no. 3, pp. 204–211, 2007.
Clinical and Laoratory Standards Institute, “Performance standards for antimicrobial susceptibility testing,” 17th Informational Supplement CLSI M100-S17, Clinical and Laboratory Standards institute, Wayne, Pa, USA, 2007.
A.-P. Magiorakos, A. Srinivasan, R. B. Carey et al., “Multidrug-resistant, extensively drug-resistant and pandrug-resistant bacteria: an international expert proposal for interim standard definitions for acquired resistance,” Clinical Microbiology and Infection, vol. 18, no. 3, pp. 268–281, 2012.
P. E. Coudron, “Inhibitor-based methods for detection of plasmid-mediated AmpC β-lactamases in Klebsiella spp., Escherichia coli, and Proteus mirabilis,” Journal of Clinical Microbiology, vol. 43, no. 8, pp. 4163–4167, 2005.
R. C. Pic？o, S. S. Andrade, A. G. Nicoletti et al., “Metallo-β-lactamase detection: comparative evaluation of double-disk synergy versus combined disk tests for IMP-, GIM-, SIM-, SPM-, or VIM-producing isolates,” Journal of Clinical Microbiology, vol. 46, no. 6, pp. 2028–2037, 2008.
P. Koirala, D. R. Bhatta, P. Ghimire, B. M. Pokhrel, and U. Devkota, “Bacteriological profile of tracheal aspirates of the patients attending a neuro-hospital of Nepal,” International Journal of Advanced Life Sciences, vol. 4, pp. 60–65, 2010.
S. Nseir, C. D. Pompeo, P. Pronnier et al., “Nosocomial tracheobronchitis in mechanically ventilated patients: incidence, aetiology and outcome,” European Respiratory Journal, vol. 20, no. 6, pp. 1483–1489, 2002.
T. Reddy, T. Chopra, D. Marchaim et al., “Trends in antimicrobial resistance of Acinetobacter baumannii isolates from a Metropolitan Detroit health system,” Antimicrobial Agents and Chemotherapy, vol. 54, no. 5, pp. 2235–2238, 2010.
H. B. V. Kumari, S. Nagarathna, and A. Chandramuki, “Antimicrobial resistance pattern among aerobic gram-negative bacilli of lower respiratory tract specimens of intensive care unit patients in a neurocentre,” The Indian journal of chest diseases & allied sciences, vol. 49, no. 1, pp. 19–22, 2007.
B. V. Navaneeth and M. R. S. Belwadi, “Antibiotic resistance among gram-negative bacteria of lower respiratory tract secretions in hospitalized patients,” The Indian journal of chest diseases & allied sciences, vol. 44, no. 3, pp. 173–176, 2002.
S. Poudyal, D. R. Bhatta, G. Shakya et al., “Extended spectrum a-lactamase producing multidrug resistant clinical bacterial isolates at National Public Health Laboratory, Nepal,” Nepal Medical College Journal, vol. 13, no. 1, pp. 34–38, 2011.
K. Lee, W. G. Lee, Y. Uh et al., “VIM- and IMP-type metallo-β-lactamase-producing Pseudomonas spp. and Acinetobacter spp. in Korean hospitals,” Emerging Infectious Diseases, vol. 9, no. 7, pp. 868–871, 2003.
G. Valenza, B. Joseph, J. Elias et al., “First survey of metallo-β-lactamases in clinical isolates of Pseudomonas aeruginosa in a German University Hospital,” Antimicrobial Agents and Chemotherapy, vol. 54, no. 8, pp. 3493–3497, 2010.
C. Urban, N. Mariano, and J. J. Rahal, “In vitro double and triple bactericidal activities of doripenem, polymyxin B, and rifampin against multidrug-resistant Acinetobacter baumannii, Pseudomonas aeruginosa, Klebsiella pneumoniae, and Escherichia coli,” Antimicrobial Agents and Chemotherapy, vol. 54, no. 6, pp. 2732–2734, 2010.
C. Franklin, L. Liolios, and A. Y. Peleg, “Phenotypic detection of carbapenem-susceptible metallo-β-lactamase- producing gram-negative bacilli in the clinical laboratory,” Journal of Clinical Microbiology, vol. 44, no. 9, pp. 3139–3144, 2006.