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Biomedical Research

Antibiotic susceptibility profiles of clinical isolates of Pseudomonas aeruginosa from Selayang Hospital, Malaysia

Author(s): Fazlul MKK, Zaini MZ, Rashid MA, Nazmul MHM

Vol. 22, No. 3 (2011-07 - 2011-09)

Fazlul MKK, Zaini MZ, Rashid MA, Nazmul MHM

Faculty of Medicine, Universiti Teknologi MARA, Shah Alam, Malaysia.

Abstract

Fifty four clinical isolates of Pseudomonas aeruginosa (P. aeruginosa) were collected from Selayang hospital, Selangor, Malaysia. Thirty six percent of the isolates were identified from pus followed by respiratory tract (22%) and urine (18.51%). All the isolates were re-identified and confirmed as P. aeruginosa in our laboratory. The antibiotic susceptibility profiles of all the isolates were determined using Kirby-Bauer disk diffusion method as recommended by CLSI. Quinolone (ciprofloxacin) was found to be the most active antimicrobial agent with 83.34% susceptibility followed by imipenem (81.49%), aminoglycosides (amikacin, 74.08% and gentamicin, 72.23%), and the beta-lactams (cefepime 62.97%, ceftazidime, 35.19%). Piperacillin showed the maximum resistance (50%) followed by ceftazidime (29.63%). It was also found that, 29% of the P. aeruginosa strains were resistant to one antibiotic, 20% strains were resistant to two antibiotics and 51% were multidrug resistant. P. aeruginosa isolated from blood, urine and sputum showed the highest rate of multidrug resistance.

Keywords: antibacterial agents, bacterial drug resistance, Pseudomonas aeruginosa
Accepted December 07 2010

Introduction

Widespread occurrences of Pseudomonas in nature were observed early in the history of microbiology. Members of the genus Pseudomonas bacterium are widely distributed in nature, but the most common human pathogen is Pseudomonas aeruginosa. (P. aeruginosa). P. aeruginosa is an important pathogen causing severe and life threatening infections in immunocompromised hosts, such as patients suffering from respiratory disease, cancer patients undergoing chemotherapy, and children and young adults with cystic fibrosis. Moreover, it is a leading cause of nosocomial infections and is associated with a high mortality rate. One reason for this high mortality is its notable resistance to many currently available antibiotics. Yet, comparative analyses of the emergence of resistance associated with different classes of antipseudomonal drugs are lacking, even though knowledge about the relative risks of resistance with different antibiotics could be useful in helping to guide therapeutic choices [1].

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 [2]. However, there are few recent surveillance studies reporting antimicrobial resistance patterns of P. aeruginosa in few locations in Malaysia [3].

Over the past few years, a notable increase in antibiotic resistance among gram negative bacteria recovered from hospitalized patients has been reported, especially for critically ill patients [4]. Infections caused by multidrug resistant (MDR) gram negative bacteria, especially MDR P. aeruginosa have been associated with increased morbidity, mortality and costs [5]. Multidrug-resistant strains of P. aeruginosa are often isolated among patients suffering from nosocomial infections particularly those receiving intensive care treatments [6].

The aim of this study was to assess the current levels of antimicrobial susceptibility and to evaluate the resistance mechanisms to antipseudomonal antimicrobial agents among the clinical isolates of P. aeruginosa isolated from patients admitted to Selayang hospital, Malaysia.

Materials and Methods

Fifty four clinical isolates of P. aeruginosa strains were collected from different patients who were admitted to Selayang hospital, Selangor, Malaysia between January 2010 and June 2010. The isolates were obtained from different clinical specimens, including pus, urine, respiratory fluids, blood, tissue, and genitalia. All the clinically isolated samples were identified as P. aeruginosa by the hospital personnel. We have re- identified all the isolates at our Laboratory by the conventional biochemical tests [7] i.e., gram staining, catalase test, oxidase test , motility test, Triple Sugar Iron Assay, citrate test, urease test and indole test etc.

Antibiotic susceptibility testing

The Kirby-Bauer disk diffusion method [8] was performed to determine the antibiotic susceptibility. The antibiotics tested were Gentamicin (10 μg), Impenem (10 μg), Amikacin (30 μg), Piperacillin (100 μg), Ciprofloxacin (5 μg), Ceftazidime (30 μg), Cefoperazone (75 μg), Piperacillin / Tazobactam (110 μg), Meropenem (10 μg), and Cefepime (30 μg). Results of disk diffusion method were interpreted in accordance to the Clinical and Laboratory Standards Institute (CLSI, 2009)

Results

The sources of clinical specimens from patients of Selayang hospital are shown in Figure1. The antimicrobial susceptibility testing revealed that P. aeruginosa strains were highly sensitive to most of the antibiotics tested, which are shown in Figure 2.

Fig 1

Figure 1. Percentage of P. aeruginosa isolated from various clinical specimens.

The percentage of sensitivities were ciprofloxacin (83.34%), imipenem (81.49%), amikacin (74.08%), gentamicin (72.23%), cefepime (62.97%), ceftazidime (35.19%), meropenem (79.63%), piperacillin (35.19), cefoperazone (22.23%), tazobactam 10/piperacillin 75 (51.86%) and the percentage of resistance were ciprofloxacin (9.25%), imipenem (16.67%), amikacin (12.97%), gentamicin (14.82%), cefepime (9.25%), ceftazidime (29.63%), meropenem (9.25%), piperacillin (50%), cefoperazone (27.78%), tazobactam/piperacillin (27.78%) (analysed from Figure 2).

Antibiotic Susceptibility

Fig 2

Figure 2. Number of bacterial strains based on antibiotic susceptibility.

Fig 3

Figure 3. Percentage of P. aeruginosa isolates sensitive to different antibiotics.

Fig 4

Figure 4. Percentage of P. aeruginosa isolates resistant to different antibiotics.

Antibiotic Resistance

Fig 5

Figure 5. Percentage of P. aeruginosa resistant to various numbers of antibiotics.

Distribution of the P. aeruginosa isolates according to the specimen type and its correlation to Multidrug Resistance (MDR) which are shown in Table 1.

Table 1. Presence of multidrug resistant isolates (MDR) based on specimen type.

Specimen Number of
specimens
No. MDR
isolates
Blood 6 4
Genitalia 1 0
Pus 20 7
Respiratory tract 12 1
Tissue 3 1
Urine 10 4
Sputum 2 2

Discussion

P. aeruginosa infection is a serious cause of nosocomial infections. With the widespread use of antibiotics and increase in the number of immunosuppressed hosts, P. aeruginosa has become a leading cause of gram-negative bacterial infections especially in immunosuppressed patients who need prolonged hospitalization [9]. The increasing rate of P. aeruginosa strains in a wide spectrum of clinical steerings determine them as emerging pathogens, especially in intensive care units (ICUs) and justifies the necessity for antimicrobial-resistance surveillance. Periodic antimicrobial resistance monitoring in P. aeruginosa infection is fundamental to updating the current activity level of commonly used antipseudomonal drugs [2].

In this present study, it was found that the out of 54 clinically P. aeruginosa isolates, 22 strains (40.74%) were identified from pus followed by urine, 10 cases (18.51%). Ciprofloxacin was found to be the most effective agents (83.34% sensitivity) followed by imipenem and meropenem (81.49% and 79.63%, respectively). Another study in Malaysia also showed 83.5% of the P. aeruginosa isolates were found to be sensitive to ciprofloxacin followed by imipenem (79.4%) and meropenem (77.3%) [2]. It was reported that the majority of meropenem-resistant P. aeruginosa showed resistance to imipenem, but almost half the imipenem resistant strains were susceptible to meropenem. Moreover, the strains resistant to meropenem were also resistant to ciprofloxacin and carbenicillin [10]. Imipenem has been reported to be very active against P. aeruginosa in a number of recent studies [11] while other has reported otherwise [12]. Resistance to 1 antibiotics29%Resistance to 2 antibiotics20%Resistance to 3 or more antibiotics (MDR)51%

In our studies the rates of antimicrobial resistance of the isolates were 9.25 % to ciprofloxacin, meropenem and cefepime, 12.97% to amikacin, 27.78% to Tazobactam, 16.67% to imipenem, 27.78% to cefoperazone, 29.63% to ceftazidime, 14.82% to gentamicin and 50% to piperacillin. A study done in another tertiary care hospital in Malaysia [3] showed the rates of antimicrobial resistance of isolates were 6.73% to amikacin, 12.9% to gentamicin, 10.1% to netilmicin, 10.9% to ceftazidime, 11.3% to ciprofloxacin, 9.9% to imipenem, 10.8% to piperacillin, 9.4% to piperacillin-tazobactam and 0% to polymyxin B while 5.74% of the strains were found to be multidrug-resistant. Raja et al., reported a low incidence of piperacillin resistance (10.8%) compared to our findings (50%) but ciprofloxacin had higher resistance rate than the present study [3]. Similarly, another study showed the resistance of piperacillin was 54.66% [13]. Drug resistance levels in different hospitals in Malaysia and others countries too have been reported in the past and antibiotics in the respective hospitals are recognized to the differential usage. When we compared to previous Malaysian studies [3], our studies showed higher resistance rates to all drugs tested except ciprofloxacin and imipenem. Among the 54 clinical isolates of P. aeruginosa tested in our study, many strains were found to be multidrug-resistant (MRD). In this study it was found that 29% of the P. aeruginosa strains were resistant to one antibiotic, 20% strains were resistant to two antibiotics and 51% were multidrug- resistant. The resistance to antibiotics of the investigated problematic strains of P. aeruginosa was higher than the mean P. aeruginosa resistance found in Malaysia [3]. In this study, P. aeruginosa isolated from blood, urine and sputum showed the highest rate of multidrug resistance. But the correlation between the multidrug resistance and the site of infection is not known.

In summary, ciprofloxacin was found to be the most active antimicrobial agent with 83.34% susceptibility followed by imipenem (81.49%). Piperacillin showed the maximum resistance (50%) followed by ceftazidime (29.63%). Fifty-one percent of the isolates were multidrug resistant. P. aeruginosa isolated from blood, urine and sputum showed the highest rate of multidrug resistance.

Reference

  1. Camell Y, Troillet N, Eliopoulos GM, Samore MH. Emergence of antibiotic-resistant Pseudomonas aerugi-nosa: comparison of risks associated with different antipseudomonal agents. Antimicrob Agents Chemo-ther 1999; 43: 1379-1382.
  2. Siva Gowri P, Nor Azura S, and Ramelah M.. Antimi-crobial susceptibility of clinical isolates of Pseudomo-nas aeruginosa from a Malaysian Hospital. Malaysian J Med Sci 2009; 16: 2-9.
  3. Raja NS, Singh NN. Antimicrobial susceptibility pattern of clinical isolates of Pseudomonas aeruginosa in a tertiary care hospital. J Microbiol Immunol Infect 2007; 40: 45-49.
  4. Fridkin SK, Gaynes RP. Antimicrobial resistance in intensive care units. Clin Chest Med 1999; 20: 303-316.
  5. Paladino JA, Sunderlin JL, Price CS, Schentag J. Economic consequences of antimicrobial resistance. Surg Infect (Larchmont) 2002; 3: 259-267.
  6. Tassios PT, Gennimata V, Spaliara-Kalogeropoulou L, Kairis D, Koutsia C, Vatopoulos AC and Legakis NJ. Multiresistant Pseudomonas aeruginosa serogroup O: 11 outbreaks in an intensive care unit. Clin Microbiol Infect 1997; 3: 621-628.
  7. Murray PR. Manual of Clinical Microbiology 2007; 9th ed., Asm Press, Washington D.C., USA.
  8. Bauer AN, Kirby WMM, Sherris J. Antibiotic susceptibility testing by a standardized single disk method. Am J Clin Pathol 1966; 45: 493-496.
  9. Korvick JA, Marsh JW, Starzl TE, Yu VL. Pseudomo-nas aeruginosa bacteremia in patients undergoing liver transplantation: An emerging problem. Surgery 1991; 109: 62-68.
  10. Bonfiglio C, Carciotto V, Russo G. Antibiotic resis-tance in Pseudomonas aeruginosa, an Italian surveys. J Antimicrob Chemother 1998; 41: 307- 310.
  11. Ling TKW, Xiong J, Yu Y, Lee CC, Ye H, Hawkey PM. The MK0826 China Study Group. Multicenter Antimicrobial Susceptibility Survey of Gram-Negative Bacteria Isolated from Patients with Community-Acquired Infections in the People’s Republic of China. Antimicrob Agents Chemother 2006; 50: 374-378.
  12. Patzer JA, Dzierzanowska D. Increase of imipenem resistance among Pseudomonas aeruginosa isolates from a Polish paediatric hospital. Int J Antimicrob Agents 2007; 29: 153-158.
  13. Prashanth HV, Shenoy S, Saldanha DR, Baliga S. Antibiotic sensitivity patterns of Pseudomonas aerugi-nosa strains isolated from various clinical specimens. Ind J Med Sci 2002. 56: 427-430.

Correspondence:
Nazmul MHM

Dept. of Microbiology
Faculty of Medicine
Universiti Teknologi MARA
Shah Alam, 40450 Selangor, Malaysia

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