Abstract
Aims and background
The hospital environment, particularly the intensive care unit (ICU), constitutes a dynamic reservoir for drug-resistant bacteria that pose a significant threat to inpatients and staff. Monitoring these microorganisms are the principal strategy for controlling infection spreading and outbreaks. But, we know sparse about the ICU environment-bacteria in Bangladesh. We aimed for microbiological study of ICU environmental samples at Bangladesh Medical University (BMU, former BSMMU) in Dhaka, Bangladesh.
Materials and methods
We bought 34 ICU environmental samples in Japan and cultured on ESBL-CHROMagar and VRE-CHROMagar media to isolate the drug-resistant bacteria. We also confirmed their susceptibility to antimicrobials using the BD Phoenix-100 system.
Results
Forty-eight ESBL-bacteria and two VRE were isolated from 34 samples. Clinically relevant ESBL-bacteria were identified in almost all samples. Klebsiellae pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa were the dominant MDR-bacteria in ICU environment. K. pneumoniae was found in the ICU bed railings (3/6, 50%), at nursing desks (2/6, 33.3%), and on infusion pump panels (1/6, 16.7%). Enterobacter cloacae was found on ICU bed railings (2/6, 33.3%), on ventilator panels (2/6, 33.3%), in the water of oxygen flowmeters (1/6, 16.7%) and at the nurse desk (1/6, 16.7%). Pseudomonas aeruginosa was mostly found in the water of oxygen flowmeters (4/5, 80%) and on ICU bed railings (1/5, 20%).
Conclusion
The ICU environment in the BMU Hospital is highly contaminated with antimicrobial-resistant bacteria, which is a contributory route for the dissemination of resistance genes among bacterial communities in the hospital.
Clinical significance
An understanding of environmental bacteria, their resistance patterns, and their clinical impact will necessarily guide to constitute an effective infection prevention and control guidelines for the hospital.
Keywords: Enterobacter cloacae, environment, Extended-spectrum beta-lactamase, Intensive care unit, Klebsiellae pneumoniae, Multidrug-resistant, Pseudomonas aeruginosa, resistant, Vancomycin-resistant Enterococcus spp
Introduction
The environment harvests microorganisms that cause clinical infections and possesses a critical route of resistant gene transmission among organisms. Thus, environmental pathogen monitoring is emphasized as an important means to predict the threat of infections and antimicrobial resistance. In our past investigation, we isolated several clinically relevant microorganisms from environmental water in Dhaka City, and those bacteria carried highly resistant genes, like extended-spectrum beta-lactamase (ESBL), in their plasmids.1 In our current understanding, the environmental route is not limited to water and air sources but also includes other components in the environment that frequently come in contact with humans and animals. Moreover, regular surveillance of microorganisms in the hospital environment is an important tool under an effective infection control program in a hospital.
The intensive care unit (ICU) in a hospital is considered an epicenter of infections, particularly multidrug-resistant (MDR) infections. This facility is also a known and frequent source of healthcare-associated infections (HAIs). Existing microorganisms and/or their resistant genes in the ICU environment can easily circulate among the ICU patients and staff, hence, the study of microorganisms in ICU environment reflects the vulnerability of an ICU to infections, including their pattern and frequency. We have very limited knowledge on the prevalence of microorganisms in ICU environments in major hospitals in Bangladesh. We aimed for microbiological study of ICU environmental samples at Bangladesh Medical University (BMU, former BSMMU) in Dhaka, Bangladesh.
Materials and Methods
This prospective study was conducted between August 2016 to April 2021. Bangladesh Medical University is a postgraduate medical university in Bangladesh with a high-standard, tertiary-level hospital. Its adult ICU is well organized, with 22 beds and standard equipment. For the study, a total of 34 swab samples were collected from seven components inside the ICU, like bed railings, water of oxygen-flowmeters, nursing desks, the central desk, ventilator panels, monitoring panels, infusion pump panels, and ICU door handles (Table 1). Beds and equipment that were being used by patients were randomly selected, and swab samples from selections were preserved in Amies media tubes and brought to a microbiology laboratory in Japan. Here, to isolate ESBL-producing bacteria, 100 µL suspensions from each tube were cultured on CHROMagar-ESBL (CHROMagar, France) media. Yielded colonies were counted, identified, and tested for antimicrobial susceptibility using the BD Phoenix-100 system (Nippon Becton Dickinson Co. Ltd., Tokyo). Extended-spectrum beta-lactamase production was further confirmed by tests using cefpodoxime and cefpodoxime with clavulanate according to CLSI guidelines.2 The samples were also cultured on CHROMagar-VRE (CHROMagar, France) media to isolate vancomycin-resistant Enterococcus spp. (VRE) in ICU environment. Growing colonies were identified by the BD Phoenix-100 system (Nippon Becton Dickinson Co. Ltd., Tokyo).
Table 1.
Environmental components in ICU
| Sl. | Components | Sample (n) |
|---|---|---|
| 1. | Nurse/doctor desks | 7 |
| 2. | Railing of ICU beds | 7 |
| 3. | ICU door handles/surfaces | 6 |
| 4. | Water of oxygen flowmeter | 4 |
| 5. | Ventilator panels | 4 |
| 6. | Infusion pump panels | 3 |
| 7. | Pt. monitor panels | 3 |
| Total | 34 |
Results
Forty-eight ESBL-bacteria and two VRE were isolated from 34 samples. ESBL-bacteria were isolated from 33 samples (97%) and VRE from two samples (5.9%), namely from one door handle connected to the washroom and from an infusion pump panel (Table 2). The highest number of ESBL-bacteria (n = 12) was found in samples from bed handles, 10 were found in nursing desk samples, seven in the water of oxygen flowmeters, six in different door handles, five in ventilator panels, four in monitor panels, and three in infusion pump panels.
Table 2.
Growth pattern in ESBL-CHROMagar and in VRE-CHROMagar media
| Sample ID | Components in ICU environment | Growth in ESBL-CHROMagar | Isolate name | Strain ID | Growtrh in VRE-CHROMagar | Isolate name | Strain ID |
|---|---|---|---|---|---|---|---|
| 1. | Railing of ICU bed 2 | + | P. mirabilis | H632 | – | – | – |
| + | Unknown | H581 | – | – | – | ||
| 2. | Water of oxygen flowmeter (ICU bed 3) | + | P. aeruginosa | H588 | – | – | – |
| 3. | Ventilator panel (ICU bed 3) | + | E. cloacae | H603 | – | – | – |
| + | A. lwoffii | H639 | – | – | – | ||
| 4. | Nurse desk (ICU bed 4) | + | Unknown | H594 | – | – | – |
| + | A. lwoffii | H638 | – | – | – | ||
| 5. | Infusion pump panel (model#131100282) | + | Unknown | H620 | – | – | – |
| 6. | Railing of ICU bed 5 | + | Unknown | H582 | – | – | – |
| 7. | Water of oxygen flowmeter (ICU bed 6) | + | Unknown | H589 | – | – | – |
| + | P. aeruginosa | H635 | – | – | – | ||
| 8. | Nursing desk (ICU bed 7) | + | P. stuartii | H596 | – | – | – |
| + | E. brevis | H650 | – | – | – | ||
| 9. | Railing of ICU bed 8 | + | K. pneumoniae | H583 | – | – | – |
| + | E. brevis | H643 | – | – | – | ||
| 10. | Ventilator panel (ICU bed 8) | + | E. cloacae | H604 | – | – | – |
| 11. | Pt. monitor panel (ICU bed 9) | + | Unknown | H608 | – | – | – |
| 12. | Nurse desk (ICU bed 10) | + | E. cloacae | H597 | – | – | – |
| + | Unknown | H651 | – | – | – | ||
| 13. | Railing of ICU bed 11 | + | E. cloacae | H584 | – | – | – |
| 14. | Water of oxygen flowmeter (ICU bed 12) | + | P. aeruginosa | H590 | – | – | – |
| 15. | Nurse desk (ICU bed 13) | + | K. pneumoniae | H625 | – | – | – |
| 16. | Railing of ICU bed 14 | + | Kl. ascorbata | H585 | – | – | – |
| + | P. aeruginosa | H633 | – | – | – | ||
| + | E. brevis | H646 | – | – | – | ||
| 17. | Ventilator panel (ICU bed 14) | + | Unknown | H605 | – | – | – |
| 18. | Pt. monitor panel (ICU bed 15) | + | Unknown | H609 | – | – | – |
| + | A. xylosoxidans subsp. | H610 | – | – | – | ||
| 19. | Nurse desk (ICU bed 16) | + | Cedecea species | H599 | – | – | – |
| 20. | Railing of ICU bed 17 | + | K. pneumoniae | H586 | – | – | – |
| 21. | Water of oxygen flowmeter (ICU bed 18) | + | E. cloacae | H591 | – | – | – |
| + | A. xylosoxidans subsp. | H592 | – | – | – | ||
| + | P. aeruginosa | H637 | – | – | – | ||
| 22. | Nurse desk (ICU bed 20) | + | Unknown | H601 | – | – | – |
| + | K. pneumoniae | H626 | – | – | – | ||
| 23. | Infusion pump panel (model#131100321) | + | Unknown | H622 | – | – | – |
| 24. | Pt. monitor panel (ICU bed 20) | + | Unknown | H612 | – | – | – |
| 25. | Railing of ICU bed 21 | + | Unknown | H587 | – | – | – |
| + | E. cloacae | H629 | – | – | – | ||
| + | K. pneumoniae | H624 | – | – | – | ||
| 26. | Infusion pump panel (model#131100276) | + | K. pneumoniae | H621 | + | E. faecium | H658 |
| 27. | Ventilator panel (ICU bed 21) | + | Cedecea lapagei | H606 | – | – | – |
| 28. | Central doctor/nurse desk | + | Cedecea davisae | H602 | – | – | – |
| 29. | ICU main entrance door (outside) | + | Unknown | H613 | – | – | – |
| 30. | ICU main entrance door (inside) | – | No growth | – | – | – | |
| 31. | ICU staff door (outside) | + | Cedecea neteri | H615 | – | – | – |
| 32. | ICU staff door (inside) | + | Unknown | H623 | – | – | – |
| 33. | Washroom connecting door (outside) | + | Unknown | H617 | + | E. faecium | H657 |
| 34. | Washroom connecting door (inside) | + | Unknown | H619 | – | – | – |
Among ESBL-bacteria, Klebsiellae pneumoniae, Enterobacter cloacae, and Pseudomonas aeruginosa were prevalent in high numbers. K. pneumoniae was found on ICU bed railings (3/6, 50%), at nursing desks (2/6, 33.3%), and on the infusion pump panel (1/6, 16.7%). Enterobacter cloacae was found on ICU bed railings (2/6, 33.3%), on ventilator panels (2/6, 33.3%), in the water of the oxygen flowmeter (1/6, 16.7%), and at the nurse desk (1/6, 16.7%). Pseudomonas aeruginosa was mostly found in the water of oxygen flowmeters (4/5, 80%) and on the ICU bed railing (1/5, 20%). There were many unknown ESBL-harboring isolates (17/48, 35.4%) (Table 2). MIC reports (Table 3) reveal that K. pneumoniae is resistant to aminoglycosides, carbapenems, quinolones, beta-lactamase inhibitors, and cephalosporins at rates of 83.3, 83.3, 100, 100, and 100%, respectively; E. cloacae at rates of 83.3, 83.3, 83.3, 66.7, and 100%, respectively; and P. aeruginosa at rates of 100, 80, 100, 80, and 80%, respectively. Vancomycin-resistant Enterococcus spp. strains were identified as Enterococcus faecium, and they were coexisting with ESBL-bacteria (Table 2).
Table 3.
Susceptibility of ESBL-bacteria to antimicrobials
| Isolates | Strain ID | Class of antimicrobial | ||||
|---|---|---|---|---|---|---|
| Aminoglycoside | Carbapenem | Flu/quinolones | Penicillin + β-lactamase inhibitor | Cephalosporin | ||
| Unknown | H581 | R | R | R | R | R |
| P. mirabilis | H632 | R | R | R | R | R |
| P. aeruginosa | H588 | R | R | R | R | R |
| E. cloacae | H603 | S | S | S | S | R |
| A. lwoffii | H639 | S | S | S | S | S |
| Unknown | H594 | R | R | R | R | R |
| A. lwoffii | H638 | S | R | R | R | R |
| Unknown | H620 | S | S | S | S | R |
| Unknown | H582 | R | R | R | R | R |
| Unknown | H589 | R | R | R | R | R |
| P. aeruginosa | H635 | R | R | R | R | R |
| P. stuartii | H596 | R | R | R | R | R |
| E. brevis | H650 | R | R | R | R | R |
| K. pneumoniae | H583 | R | R | R | R | R |
| E. brevis | H643 | R | R | R | R | S |
| E. cloacae | H604 | R | R | R | R | R |
| Unknown | H608 | R | R | R | R | R |
| E. cloacae | H597 | R | R | R | R | R |
| Unknown | H651 | R | R | R | R | R |
| E. cloacae | H584 | R | R | R | R | R |
| P. aeruginosa | H590 | R | R | R | R | R |
| K. pneumoniae | H625 | R | R | R | R | R |
| Kl. ascorbata | H585 | R | R | R | R | R |
| P. aeruginosa | H633 | R | S | R | S | S |
| E. brevis | H646 | R | R | R | R | R |
| Unknown | H605 | S | S | S | S | R |
| Unknown | H609 | S | S | S | S | R |
| A. xylosoxidans subsp. | H610 | R | R | R | R | R |
| Cedecea species | H599 | R | R | R | R | R |
| K. pneumoniae | H586 | R | R | R | R | R |
| E. cloacae | H591 | R | R | R | S | R |
| A. xylosoxidans subsp. | H592 | R | R | R | R | R |
| P. aeruginosa | H637 | R | R | R | R | R |
| Unknown | H601 | S | R | R | R | R |
| K. pneumoniae | H626 | S | S | R | R | R |
| Unknown | H622 | S | S | S | S | R |
| Unknown | H612 | R | R | R | R | R |
| E. cloacae | H629 | R | R | R | R | R |
| K. pneumoniae | H624 | R | R | R | R | R |
| K. pneumoniae | H621 | R | R | R | R | R |
| Cedecea lapagei | H606 | S | S | S | S | R |
| Cedecea davisae | H602 | S | S | S | S | R |
| Unknown | H613 | R | R | R | R | R |
| Cedecea neteri | H615 | S | S | S | S | R |
| Unknown | H623 | S | S | S | S | R |
| Unknown | H617 | S | R | S | S | R |
| Unknown | H619 | R | R | R | R | R |
Discussion
There is a huge burden of gram-negative resistance in Asia, particularly in South and Southeast Asia.3 In a recent study, we reported that 49.5% (600/1212) of isolated bacteria from patients in the same hospital were multidrug-resistant (MDR).4 The study revealed that K. pneumoniae, E. cloacae, and P. aeruginosa isolates from the patients were in the list of bacteria that harbored complex resistance mechanisms, including ESBL producers, carbapenemase producer, and concomitantly both producers. In the current study, we are reporting the existence of these clinically relevant isolates in the ICU environment in the same hospital with the same resistance pattern. It strongly suggests the role of the environment as a possible and significant route of resistance gene dissemination among bacterial communities in clinical settings in Bangladesh.
Extended-spectrum beta-lactamase-producing bacteria often display multidrug resistance. This resistance is mediated by bacterial plasmids which can also carry genes conferring resistance to other antibiotic classes. Carbapenems are still the most effective antibiotic agents against ESBL producers.5 However, as time has progressed, carbapenem-resistant enterobacteriaceae (CRE) emerged. Carbapenem-resistant enterobacteriaceae infections have limited treatment options and a significant death rate.6 We showed that ESBL-bacteria are widely distributed in the ICU environment. Furthermore, the increasing prevalence of ESBL-producing and carbapenem-resistant (CR) K. pneumoniae strains has severely limited therapeutic options, often necessitating the use of last-resort agents such as polymyxins, which are themselves becoming less effective owing to increasing resistance.7,8 We found that among ESBL-producing K. pneumoniae, 83.3% are resistant to carbapenems. This resistance in other ESBL-bacteria ranges from 70.6 to 100%. It clearly emphasizes the importance of environmental hygiene and disinfection in the infection control protocol in a clinical setting, and sparing the environment makes effective infection control unfeasible.
Vancomycin became a dominant antibacterial medication against infections caused by methicillin-resistant Staphylococcus aureus (MRSA) in the early 1950s. Thereafter, in 1988, the first types of vancomycin-resistant enterococci (VRE) were discovered. An increasing number of VRE in recent years indicates that such bacteria possess the ability to spread vancomycin resistance to other bacterial species. Furthermore, the coexistence of ESBL and VRE strains in the same environmental sample poses a greater threat to identify HAIs with extended or pandrug-resistant microorganisms in the future of Bangladesh.
Limitations
We admit the limitations of our study, like many isolates from environmental samples were not identified due to the use of the BD Phoenix-100 system, which could be identified by more advanced systems. However, the results of susceptibility to antimicrobials of those isolates helped us to understand the overall drug resistance scenario in the ICU environment. To our best information, this is the first such report from Bangladesh.
Conclusion
Antimicrobial resistance remains one of the most critical and unsolved challenges worldwide. The World Health Organization (WHO) has recognized it as a prominent threat to both global health and sustainable development.9 The increase in antimicrobial resistance among bacterial pathogens represents a serious public health concern, creating significant challenges for contemporary medical practice and increasing healthcare costs.10 Our study results align with the fact that the environment constitutes a dynamic reservoir for pathogenic bacteria, many of which pose a significant threat to human health.11 Environmental components are more considerable because of the widespread presence of bacteria and their resilience mechanisms, such as biofilm formation and resistance to disinfectants, enabling survival under harsh conditions.12–14 We reported the availability of MDR bacteria in open water resources in Bangladesh,1 in clinical settings in Bangladesh,4 and now report it in the hospital environment in Bangladesh. National surveillance on MDR bacteria is not available in Bangladesh as well as in many countries in South and Southeast Asia. Our past and current studies can be set as a milestone to understand the prevalence rate of resistant bacteria in Asia and for future MDR surveillance activities in these regions under national and international contributions.
Acknowledgment
None.
Artificial Intelligence (AI) Disclosure
No AI assisted technologies were used.
Authors’ Contributions
Anwarul Haque – Conceptualization, formal analysis, investigation, methodology, resources, and writing – original draft; Mohammad A Islam – Data curation, funding acquisition, project administration, resources, and writing – review; Abul Kalam Q Huda – Funding acquisition, supervision, resources, and writing – review; and Tetsuya Matsumoto – Conceptualization, funding acquisition, methodology, resources, supervision, writing – review and editing.
Orcid
Anwarul Haque https://orcid.org/0009-0000-0990-3626
Mohammad A Islam https://orcid.org/0009-0005-1286-8995
Tetsuya Matsumoto https://orcid.org/0000-0001-9722-7663
Footnotes
Source of support: Nil
Conflict of interest: None
Data Availability Statement
All relevant data will be available from the first author and the corresponding author.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
All relevant data will be available from the first author and the corresponding author.