Characterization and Antibiotic Sensitivity Profile of Bacteria Isolated from Patients with Respiratory Tract Infections in Bangladesh Shukla Promite1, Sajal K. Saha2, Sunjukta Ahsan1 and Marufa Zerin Akhter1 1Department of Microbiology, University of Dhaka, Dhaka, Bangladesh 2Department of General Practice, Monash University, Building 1, 270 Ferntree Gully Road, Notting Hill VIC 3168, Australia (Received: October 08, 2017; Accepted: December 15, 2017; Published (web): December 23, 2017) ABSTRACT: The study was aimed to characterize bacterial isolates from respiratory tract infections (RTI) and investigate their antibiotic sensitivity profile. Selective media and biochemical tests were used to characterize 40 bacterial isolates. Antibiotic sensitivity testing was conducted using Kirby-Bauer disc diffusion method. About 42.5% (17) RTI patients were infected by Klebsiella pneumoniae, 30% (12) by Escherichia coli and 27.5% (11) by Pseudomonas aeruginosa with no significant gender variation (p-value <0.578). Overall, 47% (out of 20) antibiotics were sensitive, whereas 48% were resistant. Surprisingly, 18% P. aeruginosa and 20% K. pneumoniae were carbapenem-resistant and 4 out of 7 cephalosporin antibiotics were highly resistant irrespective of pathogens. E. coli showed better sensitivity to nitrofurantoin (78%) and levofloxacin (89%), while K. pneumoniae was insensitive to cotrimoxazole (88%), gentamycin (77%) and piperacillin/tazobactam (66%). On the other hand, P. aeruginosa did not respond to P. aeruginosa to nalidixic acid (60%) and ciprofloxacin (60%). This study concludes that nitrofurantoin, levofloxacin, cotrimoxazole, gentamycin and piperacillin/tazobactam antibiotics could be better alternative in treating bacterial RTIs. Key words: Antibiotic sensitivity, bacterial pathogens, RTIs, Bangladesh. INTRODUCTION Antibiotic resistance (AR) is a global public The rise of AR in Bangladesh is probably due to 1 health concern. By 2050, it is estimated that drug- its difficulties in establishing bacterial etiology at the resistant infections will cause 10 million death and time of prescribing antibiotic in RTIs.9,10 Moreover, global economic loss of US $60-100 trillion if AR context and disease-specific surveillance data of 2 continues to rise at a similar pace as now. The rising antimicrobial sensitivity are limited in Bangladesh,10 bacterial resistance is common among Respiratory although this information has paramount importance Tract Infections (RTI). The causative pathogens of to develop local and national antibiotic guidelines. RTIs are Streptococcus pneumoniae, Klebsiella RTIs specific antibiotic guidelines are very important pneumoniae, Pseudomonas aeruginosa and in this context to reduce over and imprudent 1,3,4 Escherichia coli. RTIs are one of the significant prescription of antibiotics by prescribers at all levels 5 causes of global morbidity and mortality as well. from primary to tertiary care. Now-a-days in appropriate prescribing of antibiotics Taking this into consideration, this study was in RTIs has become a common malpractice by many designed mainly with two aims: i) to investigate the 6,7 prescribers. This practice further magnifies the distribution of bacterial pathogens among RTI emergence of antibiotic-resistant bacterial strains in patients and ii) to investigate their antibiotic addition to increased adverse effect, treatment cost, sensitivity profile. This study contained helpful 6-8 resource use and consultation with doctors. information for the clinicians, pharmacists and health Correspondence to: Shukla Promite policymakers about sensitive antibiotics for treating E-mail: [email protected]; Phone no: 01557258205 bacterial RTIs in Bangladesh. Dhaka Univ. J. Pharm. Sci. 16(2): 235-244, 2017 (December) 236 Promite et al. MATERIALS AND METHODS Samples were collected in this media and transported Different culture media and antibiotic disks were to the laboratory. used for growth and characterization of the bacterial Bacterial culture. Samples were inoculated onto isolates and to test their sensitivity to antibiotics. nutrient agar plate followed by incubation at 37oC for Nutrient agar (Merck, Germany), Trypticase Soy 24 hours (Figure 1). Single isolated colonies were broth (Merck, Germany), Mueller Hinton Broth inoculated onto Cetrimide agar, MacConkey agar, (Merck, Germany), Mueller Hinton agar (Merck, and Eosin Methylene Blue agar (37oC for 24 h). Germany), MacConkey agar (Merck, Germany), Colonies that were blue greenish on Cetrimide agar Eosin Methylene Blue agar (Merck, Germany), were identified as P. aeruginosa. The colonies with Cetrimide agar(Merck, Germany), Kligler’s iron agar large, pink, gummy, mucoid on MacConkey agar and (KIA) (Merck, Germany), Motility Indole Ornithine sheened with green metallic color on Eosin agar (MIO) (Merck, Germany), Simmons Citrate Methylene Blue agar were identified as K. Agar(Merck, Germany), MR-VP (Merck, Germany), pneumoniae and E. coli, respectively. Moreover, on Catalase test (Merck, Germany) and commercial MacConkey plates, E. coli showed flat, dry, pink antibiotic discs (Merck KGaA, Darmstadt, Germany) colonies with a surrounding darker pink area of were used in this experiment for biochemical precipitated bile salts. The colonies were subcultured characterization and antibiotic sensitivity of the to obtain pure cultures. isolated bacterial species. Sample collection. The sputum samples were collected from clinically diagnosed RTI infected patients attending in a private hospital in Bangladesh. The samples were collected for the period of 5 months between February to June in 2016. The research was carried out at the Department of Microbiology, University of Dhaka, Bangladesh. The population studied was a heterogeneous with different age groups (from 6 months to >70 years). A total of 40 sputum samples were collected from male (n=23) and female (n=17) patients suffered from RTIs. Demographic information was collected via the counselors after obtaining informed consent from each patient with the assurance that all information obtained would be treated confidentially. According Figure 1. Colonies on nutrient agar plate. to Gradwohl's clinical laboratory methods and Gram staining. The standard procedures were diagnosis,11 early morning sputum samples were followed to perform Gram staining for all forty collected in the autoclaved test tubes where nutrient isolates. A thin smear was prepared and the slide was agar medium was allowed to harden in a slanted air dried. Heat fixation was done by passing the slide position. For the preparation of nutrient agar, 0.5 g over a flame. The smear was flooded with crystal peptone, 0.3 g beef extract, 0.5 g NaCl, 1.5 g agar violet and was allowed to stand for 45 seconds. The were mixed with 100 ml distilled water in an crystal violet was washed away with a gentle stream Erlenmeyer flask (pH at 7.2). The media was of water followed by adding Grams iodine (mordant). autoclaved at 121°C for 30 minutes. After The smear was decolorized by adding 95% alcohol to autoclaving, 5ml of media was dispensed into each the slide and was washed away after 10 seconds. tube and allowed to solidify in a slanted position. Finally, the slide was flooded with the counterstain Characterization and Antibiotic Sensitivity Profile of Bacteria 237 safranin and allowed to stand for 1 minute. The slide Citrate test. Simmons citrate agar test was was washed, dried and was ready to be visualized performed to determine the ability of organisms to under bright field microscope. utilize citrate as a carbon source. The organism was Biochemical tests. The isolates were further citrate positive if medium turned to blue color and if distinguished by using traditional biochemical tests; the media retained its green color, the bacteria was Kligler’s iron agar test, Motility–indole–ornithine detected as citrate negative. S. aureus ATCC 25923 test, citrate utilization test, Methyl Red-Voges was used as a positive control and E. coli ATCC Proskauer test, indole test, and catalase test. 25922 was used as a negative control. Catalase test. A bacterial colony was transferred Methyl Red (MR) test. The test was performed onto a sterile glass slide using a sterile wooden stick by inoculating a colony of the test organism in 5ml of followed by adding a drop of 3% hydrogen peroxide methyl red medium. After 24 hours incubation at on the colony. Formation of air bubble indicated 37°C, a drop of methyl red solution was added. The catalase positive and no bubble production indicated tubes were then shaken and examined. A distinct catalase negative. Staphylococcus aureus–ATCC bright red color indicated MR positive test and 33592 and Enterococcus faecalis–ATCC 29212 were yellow color indicated MR negative test. used as a positive and negative control, respectively. Voges Proskauer (VP) test. For VP test, after Kligler’s iron agar (KIA) test. All bacterial inoculation and incubation of the culture tube for 24 isolates were tested for KIA test to study the mode of hours at 37°C, 0.6 ml of 5% alpha-naphthol was dextrose utilization in oxidative/fermentative test. added, followed by addition of 0.2 ml of 40% KOH. Bacterial isolate was stabbed into the butt and After gentle shaking, the tubes were kept undisturbed streaked onto the slant of KIA medium and incubated for 10-15 minutes. Red color indicated VP positive for 24 hours at 37°C. The ability of bacteria to and presence of no color indicated VP negative. ferment glucose and/or lactose, and production of Indole test. The