Indian Journal of Dermatology
: 2006  |  Volume : 51  |  Issue : 4  |  Page : 286--288

Antimicrobial susceptibility of Pseudomonas aeruginosa isolated from wound infections

Shampa Anupurba, Amitabha Bhattacharjee, Atul Garg, Malay Ranjan Sen 
 Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India

Correspondence Address:
Amitabha Bhattacharjee
Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi


The primary aim of this study was to determine the prevalence of Pseudomonas aeruginosa in wound infections and its sensitivity to the commonly used antibiotics at SS Hospital, Varanasi, India. We received 940 relevant clinical specimens among, which 301 (32%) was P. aeruginosa . Antibiotic susceptibility was determined by the disc diffusion method where cefoperazone/sulbactam was found to be most effective (74%) followed by ciprofloxacin (58%) and ceftazidime (54%). Rest of the antibiotics showed a very low level of susceptibility pattern. A total of 54 (18%) isolates were resistant to all the antibiotics tested in vitro .

How to cite this article:
Anupurba S, Bhattacharjee A, Garg A, Sen MR. Antimicrobial susceptibility of Pseudomonas aeruginosa isolated from wound infections.Indian J Dermatol 2006;51:286-288

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Anupurba S, Bhattacharjee A, Garg A, Sen MR. Antimicrobial susceptibility of Pseudomonas aeruginosa isolated from wound infections. Indian J Dermatol [serial online] 2006 [cited 2021 Nov 29 ];51:286-288
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The development of wound infection depends on the integrity and protective function of the skin.[1] It has been shown that wound infection is universal and the bacterial type varies with geographical location, resident flora of the skin, clothing at the site of wound, time between wound and examination.[2] In recent years, there has been a growing prevalence of Gram negative organisms which have almost replaced Staphylococcus aureus in nosocomial infection. Of the Gram negative bacilli, Pseudomonas aeruginosa has been of particular interest, the incidence of which in wound infection has increased compared to a decade back study.[3] It has also been observed that 28% of healthy people in hospital environment are carrier for P. aeruginosa.[4]

 Materials and Methods

The objective of this study was to determine the prevalence of P. aeruginosa in wound infection and its sensitivity pattern to commonly used antibiotics. From March '04 to August '05, 301 consecutive, non-duplicate, P. aeruginosa isolates were recovered out of 940 samples from both admitted patients and those who attended the out patient department at S. S. Hospital, Varanasi, India. Clinical specimens used for the study were pus and wound swabs. Information regarding patients age, sex, and type of specimen taken were also recorded. All the isolates were identified using colony morphology on blood agar, MacConkey agar, Gram stain characteristics, motility detection, positive reaction to oxidase, citrate utilization, and finally by pyocyanin production.[5] Antibiotic susceptibility testing was done on Mueller Hinton agar by Kirby-Bauer disc diffusion method following NCCLS recommendations[6] using ceftriaxone 30 mg, ceftazidime 30 mg, gentamicin 10 mg, tobramycin 10 mg, amikacin 30 mg, netilmicin 30 mg, ciprofloxacin 5 mg, (Hi - Media, Mumbai, India) and cefoperazone/sulbactam 75/30 mg (Pfizer, India).


The isolates were obtained from 266 pus and 35 wound swabs of 221 indoor and 80 outdoor, 208 male and 93 female patients. [Table 1] shows the rate of isolation of P. aeruginosa from patients of different wards/OPDs who had wound infections. The age groups were categorized in to four; 0-15, 16-40, 41-60, 60, and above. The result showed that the occurrence of P. aeruginosa was higher in 16-40 age group (134 nos.) and in 41-60 age group (96 nos.) than in infants (52 nos.) and elderly age group (19 nos.) while [Table 2] represents sensitivity pattern of P. aeruginosa isolated from wound infections.


Our result shows that prevalence rate of P. aeruginosa was 32% of all the pathogens isolated from wound infections. The prevalence rate is in agreement with the work done in Africa (33%)[2] as well as a previous study from India (36%).[7] More over, this work indicates that P. aeruginosa wound infection is dependent on age, sex, and duration of the stay in hospital. The infection was more common in young and middle age group then elderly people while males were more susceptible than female. Duration of stay is directly proportional as infection was much higher in indoor patients than the outdoor patients in the ratio 1: 0.36 with highest prevalence rate (29.9%) in surgery wards. This might be due to the prolonged stay in hospital following an operation resulting in colonization and subsequent infection. Similarly burn ward accounted for 21.7% prevalence rate. However, both the prevalence rates were much lower compared to previous studies.[8],[7]

The susceptibility rate of P. aeruginosa isolates to the eight antimicrobials tested in vitro were relatively low compared to the sensitivity pattern to different anti pseudomonal drugs reported world wide. In US more than 90% of the isolates were susceptible to amikacin, 80-90% of isolates were susceptible to ceftazidime while 70-80% of isolates were susceptible to ciprofloxacin and gentamicin.[9] In Trinidad and Tobago, 80 and 78.4% isolates were susceptible to ceftazidime and gentamicin respectively.[10] Reports from France have shown P. aeruginosa susceptibility rates of 78.5 and 61.7% to ceftazidime and ciprofloxacin, respectively.[11] Increased resistance was observed in Russia where only 25% isolates were susceptible to gentamicin.[12] while in Bangladesh 49 and 79% isolates were susceptible to tobramycin and ciprofloxacin respectively.[13] The earlier Indian study showing similar results to our study, reported Pseudomonas spp. was most susceptible to ceftazidime (83%) followed by cefoperazone/sulbactam (82%).[7]

In our study cefoperazone/sulbactam was highly susceptible (74%) followed by ciprofloxacin (58%) and ceftazidime (54%). Other drugs showed very low percentage of susceptibility. This might be due to the environmental condition of this particular region, genetic background of organism or frequent use of antibiotics among patients.

In the current study, 54 (18%) isolates were resistant to all the eight antibiotic tested in vitro , which is much higher compared to a Belgian study (12.2% MDR isolates)[14] but lower than the Turkish study where one third isolates were reported to be multidrug resistant.[4] Previous studies suggested that the selective pressure from the use of antimicrobial agent is a major determinant for the emergence of resistant strains. The subinhibitory antibiotic concentration in wounds, due to the administration of an inappropriate dosage of beta-lactam antibiotic or the regular administration of an aminoglycoside in combination with a beta-lactam, provides optimal conditions for the selection and persistence of multidrug resistant P. aeruginosa strains and their subsequent local invasion and hematogenous dissemination in infected wound patients.[15] Successful control of an out break of multi drug resistant clone of P. aeruginosa by increasing the daily dosage of antimicrobial agents that are active in vitro was reported previously,[16] although it has been recommended that this approach not be over used.

The prevalence and sensitivity of P. aeruginosa often varies between communities, hospitals in the same community and among different patient population in the same hospital. Faced with these variations, the physician in clinical practice has the responsibility of making clinical judgments and should have access to recent data on the prevalence and antimicrobial resistance pattern of commonly encountered pathogens. It is therefore important to institute a system for the surveillance of antimicrobial resistance that will involve the collection and collation of both clinical and microbiological data.[17]


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