|Year : 2012 | Volume
| Issue : 2 | Page : 78-80
Antibiotic resistance pattern of Pseudomonas aureuginosa isolated from healthcare associated infections at a tertiary care hospital
BV Ramana, Abhijit Chaudhury
Department of Microbiology, Sri Venkateswara Institute of Medical Sciences, Tirupati, Andhra Pradesh, India
|Date of Web Publication||1-Oct-2012|
B V Ramana
Department of Microbiology, Sri Venkateswara Institute of Medical Sciences, Tirupati-517 507, Andhra Pradesh
Source of Support: None, Conflict of Interest: None
Objectives: The present study was undertaken to assess the antibiotic susceptibility patterns of Pseudomonas aeruginosa isolated from healthcare associated infections at a tertiary care hospital. Due to significant changes in microbial genetic ecology, as a result of indiscriminate use of anti-microbials, the spread of anti-microbial resistance is now a global problem. Materials and Methods: A total of 290 Pseudomonas aeruginosa isolates from various clinical samples like urinary catheters, tips of endotracheal tube, and central venous catheter were tested for antibiotic sensitivity pattern using disk diffusion method as per Clinical and Laboratory Standards Institute guidelines. Results: The highest number of Pseudomonas infections was found in urinary catheters, followed by endotracheal tips and central venous catheters. Maximum resistance was seen to cefotaxime and gentamycin (40%) followed by ciprofloxacin (39%), amikacin (26%), cefoperazone- sulbactum (22%), piperacillin-tazobactum (16%), and imipenem (14%). Conclusion: Over all we have observed that there is increased antibiotic resistance which may be due to the selective pressure from the use of anti-microbial agents is a major determinant for the emergence of resistance strains. Antimicrobial surveillance should be done periodically to monitor the current susceptibility patterns in local hospitals.
Keywords: Antibiotic susceptibility, hospital associated infections, nosocomial infections, Pseudomonas aeruginosa
|How to cite this article:|
Ramana B V, Chaudhury A. Antibiotic resistance pattern of Pseudomonas aureuginosa isolated from healthcare associated infections at a tertiary care hospital. J Sci Soc 2012;39:78-80
|How to cite this URL:|
Ramana B V, Chaudhury A. Antibiotic resistance pattern of Pseudomonas aureuginosa isolated from healthcare associated infections at a tertiary care hospital. J Sci Soc [serial online] 2012 [cited 2019 Jul 18];39:78-80. Available from: http://www.jscisociety.com/text.asp?2012/39/2/78/101850
Pseudomonas aeruginosa is a gram-negative bacterium that continues to be a major cause of opportunistic nosocomial infections, causing around 9-10% of hospital infections.  Despite advance in medical and surgical care and introduction of wide variety of antimicrobial agents against anti-pseudomonal activities, life threatening infection caused by Pseudomonas aeruginosa continue to cause complications in hospital acquired infections.  A major reason for its prominence as a pathogen is its high intrinsic resistance to antibiotics, such that even for the most recent antibiotics, a modest change in susceptibility can thwart their effectiveness. The rapid increase of drug resistance in clinical isolates of this opportunistic human pathogen is of worldwide concern.  Unfortunately, P. aeruginosa demonstrates resistance to multiple antibiotics, thereby jeopardizing the selection of appropriate treatment. 
Multiple antibiotic resistances in bacterial populations are a pervasive and growing clinical problem, which is recognized as a threat to public health. Hence, there is a need to conduct area-specific monitoring studies to profile different pathogens responsible for specific infections and their resistance patterns, so as to generate data that would help clinicians to choose the correct empirical treatment. Ongoing surveillance of P.aeruginosa resistance against antimicrobial agents is fundamental to monitor trends in susceptibility patterns and to appropriately guide the clinician in choosing empirical or directed therapy, especially when new antimicrobial agents may not be readily available in the near future.  Therefore, the present study was undertaken to find out the antibiotic resistance patterns of pathogenic isolates of Pseudomonas aeruginosa from various specimens of healthcare associated infections (HAI).
| Materials and Methods|| |
Our study group comprised of samples, from which were clinically suspected cases of HAI. This prospective study was conducted in a tertiary care teaching hospital over a period of one year from January to December 2011. All patients with endotracheal tubes (with or without mechanical ventilation), indwelling urinary catheters and central venous catheters/venous cut-down catheters were included in the study. The common indications for insertion of the endotracheal tube were for maintenance of airway patency and for mechanical ventilation. The endotracheal tube was inserted and removed using strict aseptic technique. After extubation, the tip of the endotracheal tube was cut with a sterile blade and sent in a sterile tube for bacterial culture. The major indications for insertion of urinary catheters were to monitor urine output in hemodynamically unstable patients and in life threatening diseases like shock, multi organ failure etc. The urinary catheters were inserted and removed using strict aseptic technique. After removal, the tip of each catheter was cut using a sterile blade and sent in a sterile tube for bacterial culture. The indications for central venous catheterization/venous cut-down catheterization were- for intravenous access and/or for central venous pressure monitoring. The catheter insertion was performed under strict aseptic precautions. A short section (approximately 5 cm) of the catheter (including the area directly beneath the skin) was aseptically cut off and sent to the laboratory in a sterile tube for culture. The culture plates were incubated overnight and examined for growth. Organisms were identified on the basis of colony characteristics and biochemical reactions. The antibiotic susceptibility of the organisms (isolated from different sites) was determined using the Kirby-Bauer method (disk diffusion technique)  and the results were interpreted as per Clinical and Laboratory Standards Institute (CLSI) guidelines against a panel of anti-pseudomomal antimicrobials including imipenem, ciprofloxacin, amikacin, gentamycin, ceftriaxone, cefoperazone- sulbactum, piperacillin-tazobactum and polymyxin-B of standard strengths.
| Results|| |
Among the 290 pseudomonas isolates 150 (52%) were from urinary catheters, 80 (27%) from endotracheal tips and 6o (21%) were from central venous catheters are shown in [Table 1]. Out of 290 isolates, 203 (70%) were from males patients and 87 (30%) were from female patients. The results of antimicrobial susceptibility testing are shown in [Table 2]. Maximum resistance was seen to ceftriaxone and gentamycin (40%) followed by ciprofloxacin (39%), amikacin (26%), cefoperazone- sulbactum (22%), piperacillin-tazobactum (16%), and imipenem (14%). Minimum resistance was seen to Polymyxin-B(11%).
|Table 2: Antimicrobial resistance pattern of Pseudomonas aeruginosa isolates|
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| Discussion|| |
Pseudomonas aeruginosa emerged as an important pathogen and responsible for the healthcare associated infections that is one of the important causes of morbidity and mortality among hospital patients. Despite advances in sanitation facilities and the introduction of a wide variety of antimicrobial agents with antipseudomonal activities, life threatening infections caused by Pseudomonas aeruginosa continue to be hospital infections. The gender-wise prevalence of clinical isolates showed that infections caused by of Pseudomonas aeruginosa are very common in male (70%) compared with female (30%). Out of the 290 pseudomonas isolates 150 (52%) were from urinary catheters samples indicating that urinary tract infections are the most common HAI. 
In our study, notable resistance (14%) to P. aeruginosa was observed against carbapenems. The resistance to carbapenems, especially in P. aeruginosa, results from reduced levels of drug accumulation or increased expression of pump efflux.  The resistance may also be due to the production of metallo-β-lactamases (MBL), which can be chromosomally encoded or plasmid mediated.  The carbapenem hydrolyzing enzyme carbapenamase may be class B-metallo β-lactamases or class D-oxacillanases or class A-clavulanic acid inhibitory enzymes.
Pseudomonas aeruginosa isolated from various clinical samples has lost susceptibility and showed increasing resistance to β-lactamase inhibitor antibiotics; cefoperazone sulbactam (22%), and piperacillin-tazobactum (16%). Increasing resistance of Pseudomonas aeruginosa against β-lactamase inhibitor antibiotics may be due to excessive β-lactamase production and/or active efflux mechanism may also contribute to the full expression of β-lactam resistance in Pseudomonas aeruginosa . Multi drug efflux pumps in the inner and outer membrane of Pseudomonas aeruginosa y protect the bacterium from to β-lactam agents.
Among the aminoglycosides, amikacin has the highest sensitivity against P. aeruginosa, which is in corroboration with an earlier report published from India.  Amikacin was designed as a poor substrate for the enzymes that bring about inactivation by phosphorylation, adenylation or acetylation, but some organisms have developed enzymes that inactivate this agent as well. Amikacin seems to be a promising therapy for Pseudomonal infection. Hence, its use should be restricted to severe nosocomial infections, in order to avoid rapid emergence of resistant strains. The problem of increasing resistance to P. aeruginosa has limited the use of other classes of antibiotics like the fluoroquinolones, tetracyclines, macrolides and chloramphenicol.  Over all we have observed that there is increased antibiotic resistance which may be due to the selective pressure from the use of anti-microbial agents is a major determinant for the emergence of resistance strains.
| Conclusion|| |
Pseudomonas aeruginosa is one of the most important bacterial pathogen seriously contributing the problem of healthcare associated infection. In fact, the irrational and inappropriate use of antibiotics is responsible for the development of resistance. Hence, there is a need to emphasize the rational use of antimicrobials and strictly adhere to the concept of "reserve drugs" to minimize the misuse of available antimicrobials. Antimicrobial surveillance should be done periodically to monitor the current susceptibility patterns in local hospitals. An effective national and state level antibiotic policy and draft guidelines should be introduced to preserve the effectiveness of antibiotics and for better patient management.
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[Table 1], [Table 2]