Introduction

Antimicrobial resistance (AMR) occurs when pathogenic microorganisms develop resistance to the drugs used to control these microorganisms, made treatments less effective or ineffective [1]. The global spread of antimicrobial resistance (AMR) poses a serious threat to public health. Antibiotic resistance not only increases morbidity and mortality but also leads to a growing economic burden on health care. The World Health Organization (WHO) ranked AMR among the top 10 threats to global health in 2019 and evaluated that AMR could cause 10 million deaths annually by 2050 in the world. WHO recently reported that around 700,000 people die each year out of drug-resistant infections [2]. In spite of various agencies working towards the cause of rationalizing antibiotic usage and promoting safe prescription practices, a lot of knowledge, attitude and practice gap remains amongst the healthcare professionals especially in underdeveloped or developing nations. Lack of dynamic data’s of antibiogram at global, nationwide and regional levels often force clinicians to choose regimens based on their wisdom and prevalent local practices. The South-East Asia is considered to have the highest risk of AMR among all the WHO regions [3].

AMR is a growing threat for Bangladesh, therefore high levels of resistance to commonly used antimicrobials is observed in the country. Antimicrobials are widely available over-the-counter (OTC) in Bangladesh [4]. The overuse of antimicrobials, increased exposure to hospital and invasive procedures such as mechanical ventilation and central venous catheterization alongside disruption and breach of routine infection prevention and control (IPC) activities, including screening and isolation, may have intensified the emergence and transmission of resistant pathogens [5,6].

Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Streptococcus pneumoniae and Salmonella spp. are the commonly isolated organisms from infections in the clinical and community settings [7] and they are also the current most serious antibiotic-resistant organisms [8]. The present study aimed to determine the bacterial profile and antimicrobial susceptibility patterns of bacterial isolates from different body site infections that occurred among patients of Uttara Adhunik Medical College Hospital (UAMCH).

Materials and methods

This observational study was carried out from January to December, 2022 in the Department of Microbiology at Uttara Adhunik Medical College Hospital (UAMCH), Dhaka, Bangladesh. All laboratory procedures were performed in the Department of Microbiology, UAMCH. Total 12,337 clinical samples from patients with different diseases were collected, among which 1,679 bacteria were isolated from urine, blood, sputum and wound swabs specimen. All clinical samples were collected following standard microbiological techniques. Clinical specimens were transported to the microbiology laboratory within 2 hours. Based on sample type, the specimens were plated onto appropriate media following laboratory SOP. After an overnight incubation at 37°C for 24 hours, isolates were processed for further analysis. Bacterial species were identified using Gram staining and biochemical tests which include indole, urease, oxidase, triple sugar iron agar, citrate utilization and motility tests for Gram negative bacteria, while Gram positive bacteria were identified by Gram staining, hemolysis, catalase and coagulase tests following standard microbiological protocols [9,10]. Determination of antimicrobial susceptibility was done by disk diffusion method. Pure culture from different clinical samples were selected for determining antibiotic susceptibility pattern against  different groups of antibiotics such as Ampicillin(10µg), Amikacin(30µg), Amoxicillin/Clavulanicacid(30µg), Azithromycin(15µg), Aztreonam(30µg), Cefepime(30µg), Cefixime(5µg), Ceftazidime(30µg), Ciprofloxacin(5µg), Ceftriaxone(30µg), Cefuroxime(30µg), Cotrimoxazole(25µg), Doxycycline(30µg), Gentamicin(10µg), Levofloxacin(5µg), Linezolid(30µg), Meropenem(10µg), Netilmicin(30µg), Nitrofurantoin(300µg), Oxacillin(01mcg), Penicillin(10µg), Piperacillin/Tazobactum (100/10µg), Tetracycline(30µg), Tobramycin(10µg) and Vancomycin(30µg)  by Kirby Bauer disc diffusion method [11]. The plates were then inverted and incubated at 37°C for 24 hours. After incubation, the plates were examined and the zone of inhibition was measured in mm of diameter according to Clinical and Laboratory Standards Institute (CLSI) guideline, 2021 [12]. For antimicrobial susceptibility test Mueller Hinton agar media and antimicrobial discs were procured from Oxoid Ltd.,UK. Quality control was ensured using reference strains, including Pseudomonas aeruginosa ATCC 27853, Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923.

Results

Total 12,337 clinical specimens were processed of which 1,679 yielded positive culture and the growth rate of bacteria was 13.60% (Table 1).

Table 1: Distribution of bacterial growth pattern

Distribution of bacterial growth in different specimens were showed in Table 2. Among 1,679 bacterial isolates highest numbers (919) were isolated from urine where total urine samples were 7,768. Rate of growth was highest in case of wound swab (46.36%) where among total 302 samples, 140 yielded positive growth.

Table 2: Distribution of bacterial growth in different specimens

Table 3 observed the most common isolated bacteria was Escherichia coli 624 (37.16%) followed by Salmonella Typhi 408 (24.30%) and Klebsiella species 208 (12.40%). The least isolated organisms were Salmonella Paratyphi A 110 (6.55%), Staphylococcus aureus 95 (5.66%), Enterococcus species 59 (3.51%), Enterobacter species 66 (3.93%), Pseudomonas aeruginosa 39 (2.32%) and Acinetobacter species 38 (2.26%) respectively.

Table 3: Distribution of isolated organisms and specimens

Antibiotic susceptibility test of all the isolated bacteria were done by using different antibiotics. Among Gram positive pathogens in case of Enterococcus species all the strains were susceptible towards vancomycin and linezolid (100%). Staphylococcus aureus was found 100% sensitive towards linezolid (Table 4).

Table 4: Antibiotic susceptibility pattern of major Gram-positive organisms

Note: (-) = not tested

Table 5 presented that increased level of susceptibility was observed in case of Escherichia coli for meropenem (99.75%), amikacin (90.78%), nitrofurantoin (85.79%), gentamicin (83.99%) and piperacillin/tazobactam (71.13%). In case of Klebsiella species elevated level of susceptibility were seen in case of meropenem (93.50%), amikacin (89.17%) and gentamicin (88.64%). All the isolates of Salmonella Typhi and Salmonella Paratyphi A were susceptible to ceftriaxone and meropenem. Susceptibility percentage of cefixime, cotrimoxazole and ampicillin were 98.81%, 90.53% and 89.04% respectively in case of Salmonella Typhi and 100%, 87.50% and 97.62% respectively in Salmonella Paratyphi A. In Salmonella Typhi 1.22% strains and Salmonella Paratyphi A 2% strains were susceptible to ciprofloxacin. In case of Acinetobacter species meropenem, amikacin and gentamicin exhibited raised level of susceptibility and the percentages were 85.71%, 80.97% and 78.69% respectively. Susceptibility rate was higher for meropenem (97.22%), piperacillin/tazobactam (72%) and amikacin (71.63%) in case of Enterobacter species. All the 2nd, 3rd and 4th generation of cephalosporins showed reduce level of susceptibility in case of Escherichia coli, Klebsiella and Enterobacter species. In case of Pseudomonas aeruginosa both meropenem and piperacillin/tazobactam exhibited 71.79% and 75% susceptibility individually and 72% susceptibility was observed in case of netilmicin.

Table 5: Antibiotic susceptibility pattern of major Gram-negative organisms

Note: (-) = not tested

Discussion

In present study among the culture-positive cases, Gram negative organisms were mostly isolated in comparison to Gram positive one (Table 3). The great majority of UTIs are caused by Gram negative bacteria, most commonly by Escherichia coli and this observation is similar to another study [15]. In conflict with current study, Aika and Enato of Nigeria [16] observed Staphylococcus aureus and Coliforms as predominant organisms in their study. The difference in the pattern of bacterial isolates might be due to difference in study subjects, study design, identification method, geographic variation and variation within a study population. In our study Salmonella Typhi, Salmonella Paratyphi A, Escherichia coli, Staphylococcus aureus and Acinetobacter species were the top 5 isolates from blood cultures (Table 3). A relatively high number of Salmonella species in blood indicating a high burden of the disease in Bangladesh. Similar study was found in Chittagong, Bangladesh [17]. In this study, in case of Escherichia coli increased level of susceptibility was observed in case of meropenem (99.75%), nitrofurantoin (85.79%), amikacin (90.78%), gentamicin (83.99%) and piperacillin/tazobactam (71.13%) and decreased level of sensitivity was marked in case of 2nd, 3rd and 4th generation of cephalosporins and ciprofloxacin (Table 5). Our findings are in line with those reported in other studies where they found that Escherichia coli was highly susceptible to amikacin, meropenem, nitrofurantoin, gentamicin and ceftolozane/tazobactam [18-22]. Diminished level of sensitivity towards ciprofloxacin and 2nd, 3rd and 4th generation of cephalosporins might be due to irrational use of these drugs by clinicians, paramedics and other personnel in hospitals and other clinical settings.

In current study, Klebsiella species showed elevated level of susceptibility against meropenem (93.50%), amikacin (89.17%) and gentamicin (88.64%) and these observations were almost similar with other study where susceptibility of Klebsiella pneumoniae for antibiotics was 100% for amikacin, 82.8% for meropenem [23] but decreased level of sensitivity was marked in case of 2nd, 3rd and 4th generation of cephalosporins, ciprofloxacin, levofloxacin, nitrofurantoin and amoxicillin/clavulanate. Due to the high prevalence of resistance in Klebsiella species there is a need for strict measures in the administration of antibiotics. In opposite to current study, diminished level of susceptibility was marked in a study done by Dikkatwar et al. where in case of meropenem (10%), gentamicin (27%) and amikacin (18%) susceptibility was noted [24]. All the isolates of Salmonella Typhi and Paratyphi A were susceptible to ceftriaxone and meropenem. Similar results were observed in a study by Nasrin et al. [13] and Nazia et al. [25]. In identical with present study, lower level of ceftriaxone (38.7%) susceptibility in case of Salmonella Typhi was noted in another study [26]. In case of ciprofloxacin our study showed sensitivity of Salmonella Typhi and Paratyphi were 1.22% and 2% respectively. Similar findings were found in a study where ciprofloxacin susceptibility were 2.1% in Salmonella Typhi and 1.1% in Salmonella Paratyphi [27]. In this study, the susceptibility rate of Enterobacter species was higher in case of meropenem (97.22%), amikacin (71.63%), and piperacillin/tazobactam (72%). Reduced level of Susceptibility was marked in 3rd and 4th generation of cephalosporins (Table 5). Similar observations were found in a study where 73%, 68% and 64% susceptibility was noted in case of meropenem, amikacin and piperacillin/tazobactam respectively [28].

In case of Pseudomonas aeruginosa in present study, meropenem and piperacillin/tazobactam exhibited 71.79% and 75% susceptibility respectively (Table 5). A similar study where in case of meropenem (93%) and piperacillin/tazobactam (85%) susceptibility was observed by R et al. [29] but in contrast to present study, 51% susceptibility was observed in case of meropenem done by Iftikhar et al [30]. In our study it is showed that Acinetobacter species were 85.71% susceptible in case of meropenem and almost similar rate of susceptibility was observed in a study done in Pakistan [30]. All the isolates of Staphylococcus aureus were 100% susceptible to linezolid and increased level of susceptibility were observed in case doxycycline (90%), oxacillin (81.67%), nitrofurantoin (80%) and cotrimoxazole (70.83%) (Table 4). Like present study, Theos et al. observed Staphylococuus aureus were 100% susceptible to Linezolid [31]. This study showed all the isolates of Enterococcus species were 100% susceptible to vancomycin and linezolid and elevated level of susceptibility was marked in case of ampicillin (97.30%) and nitrofurantoin (85%) (Table 4). Like present study, another study observed higher level of susceptibility towards vancomycin (87.5%) and linezolid (93.8%) [32].

Conclusion

Bacterial antimicrobial resistance (AMR) is a significant global health challenge. This study highlights the prevalent bacterial isolates and their resistance patterns against commonly used antibiotics. The findings provide valuable insights that can support healthcare professionals in making informed, evidence-based treatment decisions and improving patient care. As the distribution of bacterial pathogens and their resistance profiles can vary across different settings, it is crucial to perform culture and sensitivity testing whenever possible before initiating antibiotic therapy. Empirical treatment should be guided by the most recent local antibiogram data. Adopting appropriate, evidence-based antibiotic policies is essential to ensure effective treatment outcomes and to combat the growing threat of antimicrobial resistance in both developed and developing countries.

Funding

Not applicable

Data Availability Statement

The dataset will be shared upon request

Conflicts of Interest

Authors declared that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Author’s Contribution

NN and MFB drafted the manuscript. MN, FR, RK, MSA, MMB and MJS validated the results and revised the manuscript.

Acknowledgements

We would like to express our gratitude to the microbiologist, data entry operators and laboratory technologists at the microbiology lab of UAMCH. We also acknowledge Dulal Mia, Shah Alam Islam, Sumon Sarkar, Milon Ahmed and Zillur Rahman for their invaluable assistance in digitizing the data.

References

1. What is antimicrobial resistance? (2017).
2. New report calls for urgent action to avert antimicrobial resistance crisis (2020).
3. Chereau F, Opatowski L, Tourdjman M, Vong S. Risk assessment for antibiotic resistance in South East Asia. BMJ 358 (2017): j3393.
4. Ahmed SM, Hossain MA. Knowledge and practice of unqualified and semi-qualified allopathic providers in rural Bangladesh: implications for the HRH problem. Health Policy 84 (2007): 332-43.
5. Rawson TM, Wilson RC, Holmes A. Understanding the role of bacterial and fungal infection in COVID-19. Clinical Microbiology and Infection 27 (2021): 9-11.
6. Patel A, Emerick M, Cabunoc MK, et al. Rapid spread and control of multidrug-resistant Gram-negative bacteria in COVID-19 patient care units. Emerging Infectious Diseases 27 (2021): 1234-1237.
7. Shih JD, Wood LSY, Dambkowski CL, et al. An in vitro bacterial surface migration assay underneath sterile barrier material commonly found in a hospital setting. J Perinatol 37 (2017): 848-852.
8. Schiavetti B, Wynendaele E, De Spiegeleer B. CIOMS Guide to vaccine safety communication. WHO Drug Inf 32 (2018).
9. Bergey DH, Krieg NR, Holt JG, et al. Bergey’s Manual of Systematic Bacteriology (1984).
10. Collee JG, Marmion BP and Fraser AJ. Practical Medical Microbiology. 14th ed. Churchill Livingstone, New York (1996).
11. Bauer AW, Kirby WMM, Sherris JC, et al. Antibiotic susceptibility testing by a standardized single disk method. The American Journal of Clinical Pathology 45 (1966): 493-496.
12. Performance standards for antimicrobial susceptibility testing, Thirty-first informational supplement, CLSI Document M 100-S31, Wayne, PA: Clinical and Laboratory Standards Institute (2021).
13. Mahfuza Nasrin, Most. Fahmida Begum, Farha Rahman, et al. Antibiogram and antimicrobial susceptibility pattern of bacterial isolates from a tertiary care hospital in Dhaka. Fortune Journals. Archives of Microbiology and Immunology 9 (2025): 31-37.
14. Yitayeh L, Gize A, Kassa M, et al. Antibiogram profiles of bacteria isolated from different body site infections among patients admitted to GAMBY Teaching General Hospital, Northwest Ethiopia. Infection and Drug Resistance 14 (2021): 2225-2232.
15. Zhou Y, Zhou Z, Zheng L, et al. Urinary tract infections caused by uropathogenic Escherichia coli: Mechanisms of infection and treatment options. Int J Mol Sci 24 (2023): 10537.
16. Aika IN, Enato E. Antibiogram of clinical isolates from primary and secondary healthcare facilities: A step towards antimicrobial stewardship. PLOS Global Public Health 2 (2022): 1-14.
17. Mahmud ASM, Hakim MA. Prevalence and antimicrobial resistance of Salmonellastrains isolated from blood cultures in Dhaka division, Bangladesh. Bangladesh Council of Scientific and Industrial Research. Department of Microbiology,University of Chittagong, Chittagong, Bangladesh. J Pure Appl Microbiol 8 (2014): 2315-2323.
18. Kasanga M, Shempela DM, Daka V, et al. Antimicrobial resistance profiles of Escherichia coliisolated from clinical and environmental samples: findings and implications. JAC-Antimicrobial Resistance 6 (2024): dlae061.
19. Naqid IA, Balatay AA, Hussein NR, et al. Antibiotic susceptibility pattern of Escherichia coliisolated from various clinical samples in Duhok city, Kurdistan region of Iraq. Int J Infect 7 (2020): e103740.
20. Olson RP, Harrell LJ, Kaye KS. Antibiotic resistance in urinary isolates of Escherichia colifrom college women with urinary tract infections. Antimicrob Agents Chemother 53 (2009): 1285-6.
21. Kuti JL, Wang Q, Chen H, et al.  Defining the potency of amikacin against Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumanniiderived from Chinese hospitals using CLSI and inhalation-based breakpoints. Infect Drug Resist 11 (2018): 783-790.
22. Dodoo CC, Odoi H, Mensah A, et al.  Development of a local antibiogram for a teaching hospital in Ghana. JAC Antimicrob Resist 5 (2023): dlad024.
23. Ayatollahi J, Sharifyazdi M, Fadakarfard R, et al. Antibiotic resistance pattern of Klebsiella pneumoniae in obtained samples from Ziaee hospital of Ardakan, Yazd, Iran during 2016 to 2017. Iberoam J Med 2 (2020): 32-36.
24. Dikkatwar M, Vaghasiya J, Mansuri F, et al. Susceptibility and resistance pattern of bacterial isolates and development of antibiogram in a tertiary care hospital of Western India. J Med Pharmaceutical Allied Sci 12 (2023): 5504-5509.
25. Rahman N, Rajib NH, Hossen MI, et al. Antibiotic resistance pattern of Salmonella Typhi and Salmonella Paratyphi clinical isolates from Dhaka, Bangladesh: A retrospective study. Faculty Office, Science and Health.
26. Ahmad M, Shah N, Siddiqui MA. Frequency and antibiotics sensitivity pattern of culture-positive Salmonella Typhi in children. J Coll Physicians Surg Pak 33 (2023): 303-307.
27. Veeraraghavan B, Pragasam AK, Ray P, et al. Evaluation of antimicrobial susceptibility profile in SalmonellaTyphi and Salmonella Paratyphi A: Presenting the current scenario in India and strategy for future management. The Journal of Infectious Diseases 224 (2021): S502–S516.
28. Walia K, Ohri V, Sahni AK. Indian council of medical research. Annual report antimicrobial resistance surveillance and research network January 2019 to December 2019.
29. RK, Anil A, Thomas P, et al. Antibiotic susceptibility profiling of Gram-positive and Gram-negative bacterial isolates in a tertiary care hospital: Establishment of an antibiogram. Cureus 16 (2024): e60542.
30. Iftikhar M, Khan I, Khan SJ, et al. Antibiogram and antibiotic resistance patterns in bacterial isolates from Hayatabad Medical Complex, Peshawar. Cureus 16 (2024): e71934.
31. Theos KR, Johnson KM, Johnson DW. Staphylococcus aureusantibiotic susceptibilities in infections in an outpatient dermatology office on O‘ahu. Hawaii J Med Public Health 78 (2019): 163-168.
32. Faroque AA, Hossain MM, Amin AMMA, et al. Antimicrobial susceptibility pattern of uropathogens isolated at a private hospital in Khulna, Bangladesh. Mediscope 11 (2024): 01-12.