Incidence of carbapenem-resistant pseudomonas aeruginosa in clinical samples

Background: Pseudomonas aeruginosa have been reported to show resistance to carbapenem drugs. Detection of carbapenem resistance pseudomonas is now important to prevent their spread as discriminates of these bacteria could be fetal to the hospitalized patients. The main objective of this study was to detection of carbapenem resistant pseudomonas aeruginosa. We also aimed to search for the treatment option for this multidrug resistant P.aeruginosa. Method: A present study was conducted over a period of 6 months. 239 isolates of Pseudomonas aeruginosa were obtained from the samples from hospitals of Pt. J. N. M. Medical College, Raipur (C.G.) from January 2015 to June 2015. These isolates were tested for susceptibility to antipseudomonal drugs and considered to be resistant to carbapenem. Antibiogram generated by disc diffusion susceptibility testing was used for clinically relevant antibiotics. Results: Out of total 239 Pseudomonas aeruginosa isolates, 25(10.46%) were found to be carbapenem resistant. All imipenem resistant isolates were sensitive to polymyxin B (300μg) and colistin (10μg). Conclusion: The rapid dissemination of carbapenem resistance is worrisome and calls for the implementation of surveillance studies as well as judicious use of antibiotics. This is a therapeutic challenge to the clinicians and also need proper selection of antibiotics especially carbapenems.


Introduction
Pseudomonas aeruginosa has been described as the most common and serious cause of infections and one of the most infectivity among all pathogenic microorganism. Problems of MDRPs are due to intrinsic as well as acquired resistance to many effective groups of antibiotics. In the past few decades, MDRPs increasing worldwide recognized as a pathogens in a variety of serious infections in hospitalized patients. [1][2][3] The carbapenemes have been drug of choice for the treatment of serious infection caused by gram negative bacterial infections. [4] Pseudomonas shows resistance to carbapenem due to decrease outer membrane permeability, increased efflux system, alteration penicillin binding protiens and carbapenem hydrolyzing enzymes carbapenemase. [5] The introduction of carbapenem, of great help to the clinician for the treatment of serious bacterial infections caused by beta lactam resistant bacteria, Carbapenem, due to their stability to hydrolysis by the most beta lactamase, have been the drug of choice for treatment of infection caused by penicillin resistant or carbapenem resistant gram negative infections. [6] Carbapenem resistance is due to the Metallo β-lactamase producing P.aeruginosa. Acquired MBLs have started spreading worldwide as a broad spectrum activity to resistance of βlactam antibiotics.
In view of the paucity of information on carbapenem resistance Pseudomonas aeruginosa infection in hospitalized patient, we undertook the present study to determine its incidence. IJBR (2015) 6 (08) www.ssjournals.com

Results
239 isolates of Pseudomonas aeruginosa from various samples were collected over 6 month of period. Out of 239 Pseudomonas aeruginosa isolates of 25 were found to be resistant to carbapenem.

Discussion
Pseudomonas aeruginosa is one of the most frequent nosocomial pathogens and the infections due to these are often difficult to treat due to antibiotic resistance. (6) carbapenem are beta lactam antibiotics, presently considered as the most potent agents of treatment of multidrug resistant gram negative bacterial infection due to the stability of these agents against the majority of β-lactamases and their high rate of permeation through bacterial outer membranes. [9] In various studies across the world, varying rates of resistance (4-60%) have been reported for imipenem and meropenem. [10] Of the Indian workers, Gladestone et al reported 42.8% carbapenem resistance among P.aeruginosa isolates. [5] Taneja et al reported that 36.4% of nosocomial urinary tract infections were caused by nonfermenters resistance to imipenem [11] In the present study, of the 239 P.aeruginosa isolates, we found that 10.46% were resistant to imipenem.
Because of its unique antipseudomonal activity ceftazidime is a reserved drug for P.aeruginosa infections. In CLSI guidelines [5] also this is included in group A drugs. In our study, 10.46% resistance was observed against ceftazidime (Table 3) which is correlate with 11% resistance observed in the study of Sarkar et al. [12] In the study of Shahid et al [13] and Pitt et al [14] ceftazidime resistance was 20% and 39.6% respectively.
In the study of Nagoba et al [15] and Veenu et al [16] amikacin was found to be most effective antipseudomonal agents. Quinolones in particular ciprofloxacin is still active against about 60% of P. aeruginosa.
We conclude the polymyxin B or colistin represent the best treatment option. However, colistin is very expensive and this limits its use. After that the best treatment options a combination of gatifloxacin, amikacin and piperacillin /tazobactam. And the last this rapid dissemination of carbapenem resistance is worrisome and calls for the implementation of surveillance studies and the judicious selection of antibiotics in clinical practice.