|Year : 2014 | Volume
| Issue : 1 | Page : 62-66
Bacteriological profile of patients and environmental samples in burn intensive care unit: A pilot study from a tertiary care hospital
Sarita Mohapatra1, Manorama Deb1, Karoon Agrawal2, Shimpi Chopra1, Rajni Gaind1
1 Department of Microbiology, Vardhaman Mahavir Medical College and Safdarjung Hospital, New Delhi, India
2 Department of Burns Plastic and Maxillofacial Surgery, Vardhaman Mahavir Medical College and Safdarjung Hospital, New Delhi, India
|Date of Web Publication||15-Dec-2014|
E/36, Ansari Nagar (West), AIIMS Residential Campus, New Delhi - 110 029
Source of Support: None, Conflict of Interest: None
Objective: Prevention of nosocomial infection in burn patient is a major challenge. Endogenous flora or the colonizers of the surrounding environment are the main source of infection in this group of patients. Continuous monitoring of infection in burn patients is necessary to evaluate the source and pattern of distribution of microorganisms. The study was planned to assess the bacteriological and antimicrobial resistance profiles of burn patients in our intensive care unit (ICU). Materials and Methods: Wound swabs from 100 consecutive burn patients were collected on days 1, 4 and 7 of admission to the burn ICU. Environmental samples were also collected from the surroundings of burn ICU and studied for the bacteriological and anti-microgram profiles. Results: Acinetobacter baumanni, Pseudomonas aeruginosa remained the major isolates from the wound swabs. Acinetobacter baumanni and Staphylococcus aureus found to be the common isolates from the environmental samples. In both the instances the strains were found to be multidrug resistant (MDR) type. Majority of the environmental colonizers were isolated from sink, bed cradle and patient's bed. Conclusion: In this study, colonizers of the environment appeared to play a major role in causation of nosocomial infection in burn patients. Hence, periodic monitoring and assessment should be done to strengthen the infection control practices in burn unit.
Keywords: Burn patients, infection control, nosocomial infection
|How to cite this article:|
Mohapatra S, Deb M, Agrawal K, Chopra S, Gaind R. Bacteriological profile of patients and environmental samples in burn intensive care unit: A pilot study from a tertiary care hospital. Indian J Burns 2014;22:62-6
|How to cite this URL:|
Mohapatra S, Deb M, Agrawal K, Chopra S, Gaind R. Bacteriological profile of patients and environmental samples in burn intensive care unit: A pilot study from a tertiary care hospital. Indian J Burns [serial online] 2014 [cited 2019 Sep 18];22:62-6. Available from: http://www.ijburns.com/text.asp?2014/22/1/62/147010
| Introduction|| |
Infection in burn patients is of a major concern as it complicates the overall management. Hands and clothing of the attending staff are the main source of hospital acquired infections (HAI) in the burn intensive care unit (ICU). , The longer the duration of stay in the hospital, more is the chance of acquiring infection. Nosocomial infection occurs due to infection by the organisms of the patient's own flora, colonizers of the environment or from health care personnel. The patients act as a niche for the microorganisms, which can further cause the spreading of infection among the other patients.  Apart from that, the environment of the burn unit is a likely source of resistant organisms from which infection can spread among patients. , Periodic surveillance of the wards and ICUs should be done and appropriate preventive measures should be taken to reduce the incidence of HAI in these patients. A prospective study was carried out in the burn ICU of our hospital to characterize the bacteriological and anti-biogram profiles of the infectious agents of these patients, and also that of the environmental samples so as to undertake appropriate preventive measures to control such infection.
| Materials and methods|| |
A prospective study was carried out in the Department of Microbiology and Department of Burns Plastic and Maxillofacial Surgery of our Hospital within a period of three months (from November 2012 to January 2013). Five trained investigators have participated in this study, among which three were clinical microbiologists and two were nursing staffs from the infection control team. Hundred consecutive patients admitted to the burn ICU of the Hospital were enrolled in this study. Ethical clearance for the study was not required as the samples from the burn patients were referred to microbiological laboratory for routine diagnostic purposes. Wound swabs from the patients were collected on the days 1, 4, and 7 of admission to ICU. Sampling from the burn wound swabs were collected after cleaning the area with 70% alcohol. The moist swab was moved around 1cm area with pressure to avoid bleeding. The swabs were plated onto blood agar and MacConkey's agar for the isolation of aerobic bacteria and identified by standard biochemical tests.  The anti-biogram pattern was determined by disk diffusion method in Mueller-Hinton agar as per the CLSI (Clinical and Laboratory Standards Institute, 2012) standards. Strains were tested for ESBL (extended spectrum of β lactamases) production by combined disk method comparing the zone of inhibition of ceftazidime and ceftazidime-clavulinic acid and cefotaxime and cefotaxime-clavulinic acid. All the Staphylococcus spp. were tested for mecA medicated methicillin resistance based on the zone of inhibition to cefoxitin disk. Environmental samples of the burn ICU set up were collected from 12 cubicles of the ICU. These included suction machine, tip of suction canula, humidifier of the ventilator, patient's bed, surgical light, intravenous fluid stand, outlet of infusion bottle, cheatle forceps, dressing trolley, sink, wall, silver sulphadiazine cream, and bed cradle. Samples from the caregivers were tried to be included in the study, but because of technical problems in collecting samples due to their shift duty hours, they were excluded from the study. Samples from the cheatle forceps, dressing, and sulfur diazine cream were taken to rule out contamination due to improper sterilization technique or inter-patient cross contamination of bacteria. Samples were collected with the help of sterile swabs wetted with glucose broth for adequate collection and growth of the organisms. Swabs from the sink include samples from the rim of sink basin and from the tap outlet 5-7 cm through the sink drain. Microbiological and anti-biogram profile were determined in the similar way as described earlier.
| Results|| |
A total of 177 isolates were identified from 182 samples collected from 100 patients. Among the day1 samples, single isolates were found in 43% and multiple isolates were found in 32% of samples; 25% of samples were reported as sterile. The bacteriological profile burn wound samples from the patients are shown in [Figure 1]. Amongst the day 1 isolates, Pseudomonas aeruginosa and Acinetobacter baumanni were most common bacteria (31.2%) followed by Klebsiella pneumoniae in 22.3% patients. Other pathogens isolated were Escherchia coli, Citrobacter freundii Proteus mirabilis, Staphylococcus aureus, Enterococcus faecalis, and β-hemolytic Streptococci. Forty percent of the sterile sample became culture positive in the follow-up samples. Bacteriological profile found to have a similar pattern of distribution in the first (4 th day) and second follow-up (7 th day) samples with a predominance of Ps. aeruginosa, Aci. baumanni and Kleb. pneumoniae [Figure 1]. The anti-biogram patterns of these isolates on the three occasions had similar type of distribution [Table 1]. Majority isolates of Ps. aeruginosa and Kleb. pneumoniae were resistant to amikacin, ciprofloxacin and netilmycin in all three occasions [Table 1]. Similarly, most of the isolates (80%) of Aci. baumanni. were resistant to amikacin, ciprofloxacin, and piperacillin-tazobactum. Imipenem, meropenem and cefoperazone-sulbactam found to be the most effective drugs for these isolates. Among the carbapenems, ertapenem and meropenem were the only two second line drugs exhibiting least resistance against these bacteria. Among the gram positive cocci, Staph. aureus was observed to be the most common isolate. In our study, gram positive cocci were the predominant pathogens found in patients with total burn surface area (TBSA) less than 20%, where as gram negative bacilli were predominant in patients with TBSA more than 20%.
|Table 1: Antimicrobial resistance pattern (in percentage) of day1, 4 (1st Follow-up) and 7 (2nd Follow-up) isolates of Kleb .pneumoniae, Ps. aeruginosa, Aci. baumanni|
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A total 168 environmental samples were collected from 12 cubicles of the ICU. Fifty-eight isolates were identified from the different environmental samples. Maximum organisms were isolated from the sink followed by bed cradle, patient's bed, and suction machine etc. [Table 2]. Aci. baumanni was the predominant isolate (46.5%) followed by Staph. aureus (15.5%) and Coagulase-negative staphylococcus (CONS) (12%), Ps. aeruginosa (10.3%), Kleb. pneumoniae (6.8%), E. coli (3.4%) and others (5.1%). Most of the Aci. baumanni. isolates were resistant to amikacin, ciprofloxacin, and netilmycin [Table 3]. However, the other gram negative isolates were found to be less resistant to these groups of antibiotics in comparison the wound isolates. Among the gram positive cocci, majority of isolates were found from bed cradle and patient's beds. Moreover, about 40% of CONS were found to be methicilin resistant in comparison to 20% in Staph. aureus. D test was positive (43%) showing resistant to erythromycin and clindamycin in most of the isolates of CONS. D test is done by the disk diffusion method to test the inducible clindamycin resistance. Clindamycin disk (2 μg) and erythromycin disk (15 μg) with a distance of 12 mm were put on the lawn culture of the test isolate on Mueller-Hinton agar plate, and incubated overnight. Blunting of inhibition zone around the clindamycin disk is taken as D test positive.
|Table 3: Antimicrobial resistance pattern (in percentage) of Aci. baumanni and Ps. aeruginosa isolated from environmental samples|
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| Discussion|| |
Hospital acquired infection (HAI) in burn patients is a major cause of morbidity and mortality. The organisms associated with the burn patients are either from the endogenous flora (normal body flora) or from the various environmental sources of the hospital. We conducted this study to learn about the etiology and distribution of infective organisms in burn patients, their change in patterns of colonization, if any, during their hospital stay. Simultaneous isolation of the environmental samples were also done to know the microbiological profile for better planning, improved hospital infection control policies, surveillance and better management of the burn patients.
Ps. aeruginosa, Aci. baumanni, followed by Kleb. pneumoniae remained the predominant pathogens in most of the samples obtained from the burn patients. They were found to be MDR except carbapenems, and cefoperazone sulbactam group of antibiotics. However, studies from other parts of the world showed Ps. aeruginosa, and Staph. aureus as predominant isolates in burn patients. ,,, Around 40% of sterile sites were replaced by Ps. aeruginosa or Aci. baumanni infection after 48-72 hours of staying in the hospital set up. This might have occurred due to infection by the colonizers from the environmental sites. Acinetobacter spp. can stay as a normal skin flora, MDR, easy to transfer, which helps in the persistence in the hospital environment for prolong period. , It was found as the most common environmental isolate followed by Staph. aureus and CONS in our study. Comparing the different sites of environmental sites, majority of the isolates were isolated from bed cradle followed by sink and patient's bed, which is a possible site of acquiring infection through the health care personnel, or nursing staff. In our study, majority of the isolates of Ps. aeruginosa and Acinetobacter spp. were also found from sink and tap, which is again a very important source of transmission of infection from one patient to another. Sink, tap and drain are the most common sources of outbreaks. It has been observed that the bacteria particularly Ps. aeruginosa forms biofilm over these areas. In shallow sinks, during water drainage these biofilms are dislodged transferring to the surrounding and ultimately to the healthcare worker's hand causing potential outbreaks. Proper hand hygiene, cohort nursing (grouping patients of a given colonization status, with designated healthcare workers and a targeted minimum ratio of 1:1 of nursing staff to patients) should be implemented to decrease the rate of nosocomial infection. , Most of Gram negative bacteria in our environmental samples observed to be ESBL positive, which enhances the transmission of resistant gene among the organisms and increase the antimicrobial resistance. In our study, one fifth (20%) of the total Staph. aureus were detected as MRSA. This is in concordance with the results of the observations made by Tauria and colleagues.  However, most of the isolates of CONS were found to be MRSA positive. There is high chance of horizontal transmission of mecA gene from CONS to Staph. aureus strains. Improper infection control and preventive measures will lead to increase rate of HAI through the healthcare personnel. Currently, emergence of vancomycin-resistant strains is also a major problem of concern. However, all the isolates, in our study were found to be vancomycin sensitive. We feel, a strict and periodic vigilance is required to know the pattern of the distribution of the organisms among burn patients. Periodic surveillance is essential to identify the etiology, anti-biogram and to monitor the incidence of nosocomial infection, which is done twice in a year in our center (unpublished data). Efficient surveillance results in early detection of changes and patterns of infection, and thereby provides information regarding subsequent steps like improvement and quality check of the sterilization technique, disinfection of the environments, further planning and improvement in various procedures etc. Hand hygiene, awareness of healthcare workers, cohorting etc. should be strictly followed up to reduce the transmission of colonizers from environment to host.
| Conclusion|| |
The result of present study showed that Aci. baumanni and Ps. aeruginosa are the leading causes of infection in burn patients. The MDR seen in the isolates is also a matter of concern. Frequent and periodic microbiological surveillance would not only let us know the bacteriological and anti-biogram profiles of the hospital strains, but also help taking appropriate measure for reducing the rate of nosocomial infection and complications. Although, genotypic or DNA-typing methods are the best methods to establish the clonality, species level identification by various phenotypic tests and antibiogram in the appropriate clinical settings may provide strong evidence for epidemiological link. Hence, all attempts should be made to reduce the transmission of MDR bacteria. The results from our study highlighted about the recent scenario of the burn patients and their surrounding environment. Environmental strains appear to transfer from the different environmental sites to the burn patients. It will be helpful in formulating better preventive measures, effective therapy, and hospital infection control practices.
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[Table 1], [Table 2], [Table 3]