Pseudomonas aeruginosa is one of the most common pathogenic bacteria, frequently found in different environmental samples. The prevalence of multidrug resistant isolates has become an alarming concern for both patients and their surroundings. The present study was carried out to record prevalence of P. aeruginosa in surface water of Dhaka city and to screen their antibiotic resistance pattern. The study was also extended to typing of resistant isolates according to extended spectrum beta lactamase production. Hereby, Kirby-Bauer method was applied to test antibiotic sensitivity according to Clinical and Laboratory Standards Institute. Then, the Ampicillin resistant isolates were screened for ESBL production by Double Disk Synergy Test (DDST). In these prospects, 52 water samples were tested, of which 32 were found positive for P. aeruginosa isolates. Hundred percent of the positive isolates were found to Ampicillin (AMP) resistant followed by 93.7% to both Tetracycline and Gentamycin and 71.8% to Co-triimoxazole. P. aeruginosa is completely susceptible to third generation antibiotics ciprofloxacin, Imipenem and Aztreonam followed by moderately susceptible to Polymyxin-B (78.2%) and Colistin (87.5%). According to DDST, all of the susceptible isolates were found positive for AMC type beta-lactamase production. It is evident from this study that the surface water is contaminated with antibiotic resistant P. aeruginosa and that through the water systems antibiotic resistance can be transferred to humans and animals. So, appropriate and rationale use of antibiotic should be applied to minimize the emergence of multidrug isolates to environment.
Pseudomonas aeruginosa is a clinically important gram negative bacterium, which is responsible for a variety of systemic infections like urinary tract infections, respiratory system infections, gastrointestinal infections, dermatitis, bacteremia, soft tissue infections, bone and joint infections [
P. areuginosa is highly ubiquitous in water system and capable to acquire antibiotic resistance due to its low outer membrane permeability and extensive efflux pump system [
Dhaka is one of the densely populated cities in the world. There are a huge number of hospitals and clinics in Dhaka City where different antibiotics are used frequently. After their use in various treatments such as medicine, veterinary medicine and growth promoters in animal husbandry, fish farming and other fields’ antibiotics are released into the water environment. Frequent use of antibiotics in treatments plays an important role in the emergence of resistant bacteria [
Bacteria resistant to antibiotics have been detected in different compartments such as waste water, surface water, ground water, sediments and soils. It is necessary to study the presence of clinically important bacteria in environment and their antibiotic resistance pattern. In the past two decades, the emergence of resistance to antimicrobial agents has been repented as one of the most important clinical crisis [
The objectives of the present investigations were to assess the prevalence of P. aeruginosa in surface water and to screen its antibiotic resistance pattern. Finally, the resistant isolates are classified according to extended spectrum beta-lactamase production.
The overall study was carried out over a period of eight months. All of the samples were collected in two phases: firstly, at the initial period on summer season and secondly, at the late period on winter season. Overall Dhaka city was sub-divided into north and south zone to facilitate the collection of sample. Water samples were collected from various ponds, lakes and rivers in Dhaka city. And all the samples were stored in sterile bottle at 40 C until processing. Within 4 hour all of the samples were processed accordingly.
5 ml of water sample was added to 20 ml Baumann’s enrichment medium and incubated overnight without shaking at 300˚C. Then the sample was streaked for isolation on Mac Conkey agar and incubated at 300˚C for 18 - 22 hrs. Predominant colorless colony for Pseudomonas aeruginosa on MacConkey agar was selected for characterization.
According to the society of American Bacteriologists [
Antimicrobial susceptibility tests were performed to measure the ability of an antibiotic to inhibit bacterial growth in vitro by disc diffusion. This test was performed by modified Kirby-Bauer method [
The isolates those are resistant to Ampicillin were screened for ESBL production by the double disc synergy test [
52 water samples were collected from different water sources like ponds, lakes and river of Dhaka city. Around them thirty two samples were found positive for P. aeruginosa. Out of the 32 positive isolates, 13 were from ponds, 16 from lakes and 3 from river. The highest isolation rates of P. aeruginosa was found in lake (69.5%) followed by river (60%) and ponds (54.1%). The prevalence rates of P. aeruginosa recovered from different surface water is given in
A number of clinically important antibiotics such as Gentamycin, Ciprofloxacin, Ampicillin, Tetracycline, Polymixin-B, Colistin and Co-trimoxazole were used to test the resistant pattern of Pseudomonas aeruginosa. It
Site of collection | No. of sample examined | No. of positive isolates (%) |
---|---|---|
Ponds | 24 | 13 (54.1%) |
Lake | 23 | 16 (69.5%) |
River | 5 | 3 (60%) |
Total | 52 | 32 (61.5%) |
was found that the isolates were mostly resistant to Ampicillin (100%), Tetracycline (93.7%) and Gentamycin (93.7%). On the other hand, they were moderately resistant to co-trimoxazole (71.8%) but marginally resistant to polymixin-B (21.8%) and Colistin (12.5%). Paradoxically, the isolates were completely sensitive to third generation antibiotic Ciprofloxacin (100%) (
In the extension of present study, all of the isolates were found completely resistant to the third generation antibiotics Cephalosporins (Cefotaxime and Ceftazidime). Ironically, they were found susceptible to ciprofloxacin, Imipenem and Aztreonam. Ampicillin clavunice acid was also tested to determine ESBL production by the isolates. Surprisingly, the resistant isolates were also found resistant to Ampicillin clavunic acid. All of these test result suggest that 100% isolates were positive for ESBL production and according to the Ambler and Bonnet classification [
P. aeruginosa is one of the important bacterial pathogens ubiquitous in different environmental sample. Despite advances in medical and surgical care and introduction of wide variety of antimicrobial agents in animal and agriculture, resistant isolates increases dramatically in environmental surface water. Therefore, different water sources could create a widespread pool of resistant microbes from which resistance could be transferred back into human and animal disease organisms. So the present study was carried out to find out the proportion of the resistance isolates in surface water and to screen their antibiotic resistance pattern.
In the present study, 52 water samples were collected from three different water sources in Dhaka city like ponds, rivers and lakes. Around them 32 samples were found to be positive for P. aeruginosa isolates. The highest isolation rates of P. aeruginosa was found in lake (69.5%) followed by 60% in river and ponds were for 54.1%. The isolation rate of different water samples could vary due to source and size of sample as well as time and duration of sample collection. However, in Bangladesh the average isolation rate from different surface water for P. aeruginosa is 61.5% which is relatively higher than its neighboring country India that was found 45.45% by Sivaraj et al. in 2011 [
This current study mainly focused to the characterization of antibiotic resistant pattern of P. aeruginosa isolated from different sources of surface water. Here, mostly used anti-pseududomonal agents in Bangladesh were tested against Pseudomonas aeruginosa isolates to screen their resistant pattern. Those antibiotics were Penicillin (Ampicillin), Carbapenem (Imipenem), third generation cephalosporins (Cefotaxime, Ceftadizime and Aztreonam), Polymixin (Polymixin-B and Colistin), Sulphonamide (Co-trimoxazole), Tetracycline, aminoglycosides (gentamycin), Quinolones (Ciprofloxacin), and Ampicillin combination (Ampicillin clavunic acid).
According to the Disk Diffusion Method, isolates were found 100% resistant to Ampicillin and similar result was found also in Pakisan in 2010 for clinical samples [
The present study detected 93.7% isolates were resistant to both Tetracycline and Gentamycin antibiotic. An elevated rate of resistant was also found in 100% in Egypt [
Two Indian study in 2012 [
Isolates (N = 32) | Susceptibility to | Types of Beta- lactamases production | |||||
---|---|---|---|---|---|---|---|
Ampicillin | Ampicillin clavunic acid | Cefotaxime | Ceftadizime | Aztreonam | Imipenem | ||
P. aeruginosa (100%) | R | R | R | R | S | S | AmpC (class C/group 1) |
71.8% resistant to Co-trimoxazole was found in this study which was slightly lower than 93.5% resistant isolates shown in study of Rashid et al. [
12.5% resistant to Colistin was found in this work where an Indian study of Angadi et al., found 15.2% resistance [
The isolates of this present study were found to be completely sensitive to third generation antibiotic Ciprofloxacin (100%). But a completely different situation was found by Rashid et al. (2012) in also in Bangladesh. They isolated Pseudomonas aeruginosa from clinical sample where they saw, 75.5% isolates were resistant to ciprofloxacin [
The present study was also extended to classify the isolated P. aeruginosa according to beta lactamases production. Double disc synergy test suggests that all of the isolates were susceptible to Imipenem and Aztreonam and were completely resistant to third generation antibiotic Cephalosporins (Cefotaxime and Ceftazidime). An Indian study in 2012 showed that 86% and 61% isolates susceptible to Imepenem and Aztrenam respectively [
These DDST suggested that the isolated P. aeruginosa were competent for ESBL production. And according to the Ambler and Bonnet classification [
It is evident from the study that now a day’s P. aeruginosa is becoming less sensitive to cephalosporins, aminoglycosides and other B-lactamase inhibitors. And the surface water is somehow contaminated with such antibiotic resistant P. aeruginosa and through the water systems antibiotic resistance transferred to human and animal. Thereby, the living organism gradually becomes multidrug resistant. To prevent the spread of the resistant bacteria, it is critically important to have strict antibiotic policies while surveillance program for multidrug resistant organisms and infection control procedures need to be implemented.
Different sources of environment can play an important role in the spreading of P. aeruginosa [