Bacteriological spectrum of urinary, wound and respiratory infection with antibiogram of gram negative bacteria in a Bangladeshi tertiary care hospital

Infection remains the main cause of morbidity and mortality in man, particularly in developing areas where it is associated with poverty and overcrowding. Infectious disease cause nearly 25% of all human deaths. This rate of mortality is increasing day by day due to antibiotic resistance, which is a major concern nowadays. Wound, respiratory tract and urinary tract are commonly associated with bacterial infection in both hospital and community settings. Area-specific monitoring studies aimed to gain knowledge about the type of bacterial pathogens responsible for these kinds of infections and resistance pattern of the causative agents may help clinicians to choose correct treatment regimen. So, the present study was aimed to investigate the pattern of bacteria which are responsible for Urinary tract, respiratory tract and wound infection. In addition, we also determined the antibiotic susceptibility profile of gram negative bacteria isolated from the patients who were attending both in and out patient departments at Sir Salimullah Medical College & Mitford Hospital (SSMC & MH) during January, 2009 to December, 2009. In this cross-sectional study, out of 308 clinical samples, a total of 159 (51.62%) samples were found to be positive for bacterial culture. Among the isolates 139 (87.42%) were Gram negative bacteria (Esch. coli, Klebsiella spp., Proteus spp., Pseudomonas spp., Acinetobacter spp.) and 20 (12.57%) were Gram positive bacteria (Staphylococcus aureus, Coagulase negative Staphylococcus). Antibiotic susceptibility of gram negative bacteria showed members of the Enterobacteriaceae were 100% sensitive to imipenem while they were found variably resistance to other commonly used antibiotics. We conclude that infections in the wound, respiratory and urinary tract are caused by both gram negative and gram positive bacteria. However, the frequency of gram negative bacteria is higher than the gram positive bacteria for these infections. Gram negative bacteria showed sensitive to imipenem and most of them were resistant to commonly used antibiotics. Therefore, clinicians should choose imipenem for patients who would be unresponsive to commonly used antibiotics.


Introduction
Bacterial Infection remains the main cause of morbidity and mortality in humans, particularly in developing countries like Bangladesh. This rate of mortality is increasing day by day due to antibiotic resistance, which is a major concern now a day. The term antimicrobial resistance (AMR) refers to the microorganism, that is able to survive in spite of antibiotic treatment. Antimicrobial resistance developed from several intrinsic factors such as point mutation, gene amplification and extrinsic factors like horizontal transfer of resistant gene between bacteria by plasmids, sex pillis or transposons. These Resistant bacterial pathogens are now challenging to the clinicians and researchers which cannot be reduced once developed even by restricting the antibiotic usage. World Health Organization (WHO) recommends for the emergence of hospital and community acquired resistant bacterial infections due to inappropriate and irrational uses of antibiotics in humans and animals for the therapeutic and nontherapeutic purposes (as growth promoters). In addition, some social factors include demographic change; poverty; poor hygienic practices and overcrowding have been referred as the emergence of multidrug resistant (MDR). 1 The multi-drug resistant organisms create serious medical problem globally that has significantly affected the treatment of infectious diseases. [2][3][4][5] The surveillance of previous studies showed bacterial antimicrobial resistance pattern can differ significantly from one country to another even different regions within the same country. [6][7][8][9] In Bangladesh, development of multi-drug resistance in clinical isolates of gram negative bacterial species like Salmonella typhi, Pseudomonas spp. and Klebsiella spp. has been also reported. [10][11][12] The investigation of antibiotic susceptibility is important particularly in developing countries like Bangladesh that do not control antibiotic usage and maintain adequate epidemiological surveillance. In addition, poverty and overcrowding allows rapid transmission of infectious diseases with resistant organisms in Bangladesh. Thus, we aimed to analyze the causative bacterial agents for wound, respiratory and urinary infection and antibiotic susceptibility of gram negative bacterial pathogen in a tertiary care hospital in Bangladesh. Therefore, the outcome of our study might be important to identify the resistant drugs, which will help the physicians to choose right antibiotics against wound, respiratory and urinary tract infection.

Materials and methods
This cross-sectional study was carried out in the department of Microbiology, SSMC & MH for a period of one year from January, 2009 to December, 2009. Total 308 samples of wound swab, throat swab and urine were collected from in-patient and out-patient department of Sir Salimullah Medical College & Mitford Hospital. Samples from patients clinically suspected to have urinary tract infections, wound infection and respiratory tract infection were collected. Samples were collected aseptically in sterilized bottles or disposable sterile tubes and submitted to clinical Microbiology laboratory.

Culture
All wound swabs, urine samples and throat swabs were inoculated in Blood agar and MacConkey agar media. Throat swabs were also inoculated on Chocolate agar media by calibrated loop technique. All the plates were incubated at 37° C aerobically. After overnight incubation, plates checked for presence of suspected pathogens.

Isolation and identification of organisms
All the organisms were identified by their colony morphology, staining character, pigment production, motility and other relevant biochemical tests as per standard methods. 13,14 Prior to the above mentioned tests for detection of urinary pathogens from plate, colony count was done by calibrated loop method. 15

Media for antibiotic sensitivity test
Mueller-Hinton agar media was used for antimicrobial susceptibility testing for all the bacteria. 16

Antimicrobial sensitivity test
All bacterial isolates were tested for antimicrobial susceptibility by disc diffusion method against different antimicrobial agents. 16

Results
Total 308 samples were collected from patients with suspected wound infection (swab from surgical wound and other wounds), respiratory tract infection (throat swab) and urinary tract infection (urine) from SSMC & MH of which 207 were urine samples, 96 were wound swab samples and 5 were throat swab samples (  In this study antibiogram was only determined only against Gram negative bacteria, which demonstrated that-E.coli, Klebsiella, Proteus and Pseudomonas showed around or more than 80% resistance to Amoxicillin, Cephradine and tetracycline. Moreover, these bacteria were around or more than 60% resistance to Cotrimoxazole, Azithromycin, Aztreonam, Ciprofloxacin and Nalidixic acid. In addition, resistance to Ceftrixone, Ceftazidime, Cefotaxime, Mecillinam, Gentamicin and Chloramphenicol were around or more than 40% among these isolated bacteria. We also determined the antibiotic sensitivity pattern of these bacteria. E. coli and Klebsiella spp. have shown good sensitivity pattern against Netilmicin, Nitrofurantoin and Amikacin, such as, E. coli (76%, 81% and 80%) and Klebsiella spp. (67%, 34% and 67%); whereas, Proteus and Pseudomonas showed less sensitivity to these antibiotics. As only one Acinetobacter was isolated that's why it has not so significant value regarding antimicrobial sensitivity pattern. All isolates were 100% susceptible to imipenem (Table 03).
Mediscope 2020;7(1): 17-24 20   20 The author also found both gram negative and gram positive bacteria showed high resistance against amoxicillin, ciprofloxacin, co-trimoxazole and ceftriaxone but good susceptibility to gentamicin and levofloxacin. 20 Furthermore, Rahman et al. (2007) also found sensitivity to imipenem was 94-100% for Enterobacteriaceae, 93.0% for Pseudomonas and 97.0% for Acinetobacter spp. 19 This study also reported Enterobacteriaceae was sensitive to third-Generation Cephalosporins like Ceftriaxone, Ceftazidime and Cefotaxime (45-66%), Gentamicin (52.8-67.9%) and Ciprofloxacin (33-40%) but resistant to Ampicillin.19 This author also found that Acinetobacter was sensitive to thirdgeneration Cephalosporins (50-56%), Ciprofloxacin (40.6%) and to Chloramphenicol, Co-trimoxazole, Cephalexin and Ampicillin (9.3%-34.3%). 19 As only one Acinetobacter was isolated by our study, that's why it did not have a significant value regarding antimicrobial sensitivity pattern. Drug resistance surveillance before the induction of therapy is necessary to guide the appropriate and judicious antibiotic use.

Conclusion
In conclusion, both gram negative and gram positive bacteria were responsible for wound, respiratory and urinary tract infection, but frequency of infection with Gram negative bacteria was much higher than Gram positive bacteria. All the gram negative bacteria were sensitive to imipenem and most of them showed resistant to commonly used antibiotics. Therefore, clinicians can consider imipenem for patients those who remain unresponsive to commonly used antibiotics.