Four Year-Surveillance for Multidrug-Resistant Pathogens at Chiang Mai University Hospital, Thailand

Background: Surveillance is conducted for a myriad of reasons. Conducting surveillance for multidrug-resistant organisms leads to identify changes in the pathogens causing HAIs of specific sites, and the antimicrobial susceptibility patterns. 

Objective: To surveillance multidrug-resistant pathogens over 4 years

Methods: Clinical laboratory reports from Chiang Mai University hospital were reviewed from 2006 to 2009.

Results: During the 4-year period, gram-negative bacteria were the majority of isolates. Overall, Escherichia coli was the most common pathogen isolated from patients, followed by Pseudomonas aeruginosa and Acinetobacter baumannii. A. baumannii was the most common pathogen isolated from sputum, followed by P. aeruginosa, and Klebsiella pneumoniae. E. coli was the most common pathogen isolated from blood, followed by K. pneumoniae, and Staphylococcus aureus. E. coli, followed by Enterococci and K. pneumoniae were the three most common pathogens isolated from urine. S. aureus was the most common pathogen isolated from wound and pus, followed by P. aeruginosa, and E. coli. Extended-spectrum ß-lactamase producing strains were accounted for 35.2% and 49.2% among E. coli and K. pneumoniae, respectively in 2006 and 53.2% and 56.5% in 2009. Less than 1% of ESBL-producing E. coli was resistant to meropenem for all 4 years. However, ESBL-producing K. pneumoniae which resisted to meropenem was less than 1 % in 2006 and 2007, and increased to 1.7% in 2008 and 2009.  The percentage of meropenem resistant among P.  aeruginosa was 35.0%, 33.8%, 27.0%, and 26.8% in 2006, 2007, 2008, and 2009, respectively. The percentage of piperacillin/tazobactam resistant among P. aeruginosa was less than 20% for all 4 years. The percentage of meropenem resistant among A. baumanii isolates was 67.1%, 74.2%, 68.9%, and 74.2% in 2006, 2007, 2008, and 2009, respectively. Among meropenem-resistant A. baumanii isolates, 33.3%, 66.2%, 20.1%, and 8.8% were susceptible to cefoperazone/sulbactam in 2006, 2007, 2008, and 2009, respectively. Gram-positive bacteria were accounted for 25% of all isolates for all 4 years. S. aureus and Enterococci were the most common gram-positive pathogens. Among S. aureus, 35% and 44% were methicillin-resistant strains in 2006 and 2009, respectively. Vancomycin-resistant enterococci was reported in 1, 2, and 5 isolates in 2006, 2007, and 2009, respectively.

Conclusions: The surveillance data showed that gram-negative bacteria are the major problems in our hospital. Multidrug-resistant Acinetobacter baumannii is a problem concerned. Carbapenem-resistant Enterobacteriaceae is increasing from the previous year. Continuing surveillance is essential to monitor the trend of these multidrug-resistant bacteria.