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Year : 2016  |  Volume : 34  |  Issue : 4  |  Page : 529--532

High fungal spore burden with predominance of Aspergillus in hospital air of a tertiary care hospital in Chandigarh

SM Rudramurthy1, G Singh1, V Hallur1, S Verma2, A Chakrabarti1,  
1 Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh, India
2 Department of Internal Medicine, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Correspondence Address:
S M Rudramurthy
Department of Medical Microbiology, Postgraduate Institute of Medical Education and Research, Chandigarh


The prevalence of fungal spores in the hospital air is essential to understand the hospital-acquired fungal infections. Air conditioners (ACs) used in hospitals may either reduce spores in air or be colonised by fungi and aid in its dissemination. The present study was conducted to assess the fungal spore burden in AC and non-AC areas. We found a high fungal spore count in air irrespective of whether the area was AC or non-AC. The most predominant species isolated were Aspergillus flavus and Aspergillus fumigatus. Such high concentrations of pathogenic fungi in air may predispose individuals to develop disease.

How to cite this article:
Rudramurthy S M, Singh G, Hallur V, Verma S, Chakrabarti A. High fungal spore burden with predominance of Aspergillus in hospital air of a tertiary care hospital in Chandigarh.Indian J Med Microbiol 2016;34:529-532

How to cite this URL:
Rudramurthy S M, Singh G, Hallur V, Verma S, Chakrabarti A. High fungal spore burden with predominance of Aspergillus in hospital air of a tertiary care hospital in Chandigarh. Indian J Med Microbiol [serial online] 2016 [cited 2020 Oct 1 ];34:529-532
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The mortality of fungal diseases parallels malaria or tuberculosis and is estimated to be around 1,350,000 patients per year.[1] A large number of fungi causing human disease are known to enter the human body through the respiratory tract and cause disease in susceptible hosts both in hospital settings and in community. It is important to understand the fungal composition of air in the hospital environment and its effects on the health.

In developing countries, certain areas of the hospital such as private wards, emergency complex and Intensive Care Units (ICUs) are subjected to climate control using air conditioners (ACs). Central air conditioning systems also have a bearing on fungal load as fungi tend to colonise AC ducts and filters. Hence, we studied the aeromycoflora of AC and non-AC areas of a tertiary care hospital in North-west India.

 Materials and Methods

Air sampling was performed twice a month from January to December 2012 (except February) at emergency ward (AC) and general medical ward (non-AC) of our 1800-bedded hospital using a portable centrifugal air sampling system (Hi-Media, Mumbai; 40 L/min of air onto malt extract agar strip). Agar strips were incubated at 25°C for 7 days and checked for growth after 24 h, 48 h, 72 h and 7 days. Mycelial growth obtained was identified using standard mycological methods (morphology). The spore count in air was expressed in colony forming units/mm 3 of air sampled (CFU/mm 3). AC and non-AC areas were compared for presence, nature and count of fungi obtained upon sampling. The analysis of spore counts obtained from various wards was analysed statistically by the Student's t-test using Microsoft Excel 2010.


Aspergillus flavus, Aspergillus fumigatus, Aspergillus niger, Penicillium spp., Rhizopus arrhizus, Rhizopus microsporus, Alternaria alternata, Curvularia lunata, Fonsecaea pedrosoi, Bipolaris hawaiiensis, Fusarium solani, Fusarium oxysporum, Acremonium spp., Candida albicans, Candida tropicalis, Geotrichum, Trichosporon spp., and some unidentified fungi were isolated during the study period. Only moulds were included for further analysis. The average spore count in the AC area and the non-AC area was 82 CFU/m 3 and 122 CFU/m 3 respectively. The details of the spore counts of various fungal agents in the AC and non-AC area are presented in [Table 1]. Members of the genera Aspergillus were the most common mycelial fungi isolated throughout the year in AC area and the non-AC area (except during April and October in AC area when black fungi were isolated in higher number). On comparing the various groups of fungi isolated from AC and non-AC areas, the average number of Aspergillus spp. isolated from the non-AC area were significantly higher (P = 0.013) in comparison to the AC area. Among the members of the genus Aspergillus, A. flavus was the most common species isolated followed by A. fumigatus. [Figure 1]a and [Figure 1]b represent month-wise distribution of Aspergillus spp. in air sampled from AC and non-AC area of the hospital, respectively. There was no significant difference in the average spore counts of the other group of fungi in the AC and non-AC areas during different seasons.{Table 1}{Figure 1}


The results of this prospective surveillance study on hospital air in AC and non-AC areas show that (i) there were high levels of fungal spores in the hospital air regardless of whether the rooms were AC or not, (ii) Aspergillus spp. were found in high numbers both in AC and non-AC areas, (iii) no significant seasonal variation was seen in the distribution of the fungi with regards to the average spore counts.

Although there are no strict numerical guidelines for determining the level of fungal contamination in hospital air, the national guidelines of the United Kingdom for prevention of nosocomial aspergillosis for interpretation of the fungal spore burden state that the fungal spores in air should be ≤5 conidia/mm 3 in the absence of air filtration. In the present study, we considered the level more than this limit as high fungal spore burden in our hospital's air.[2] Historically, several reports of outbreaks of invasive aspergillosis (most commonly due to A. fumigatus and A. flavus) attributed to construction have been reported in bone marrow transplant, renal transplant, acute leukemia and other immunocompromised patients. However, there was one report of nonconstruction-related invasive aspergillosis that occurred in two patients with chronic obstructive pulmonary disease on mechanical ventilation following air filter change. It has been shown in the past that concentrations of Aspergillus spp. below 1 CFU/m 3 may be sufficient to cause infection in high-risk patients. The average spore counts in the AC area and the non-AC area were 82 and 122 CFU/m 3, respectively. Similar counts were observed at a hospital in Minneapolis, USA, and also by Pini et al., but were higher than reported by other authors.[3],[4],[5] Martiniz-Diniz et al. reported higher mean load of fungal spores from their hospital in Sao Paulo, Brazil.[6]A. flavus was the most common mould in AC and the second most common mould in non-AC areas. Although A. flavus is the second most Aspergilli to be isolated from human cases worldwide, it is more common than A. fumigatus in air in India and certain other countries. Further, in animal models it has been demonstrated that it is 100 times more virulent than A. fumigatus.[7],[8] Considering the above and the fact that concentrations of Aspergillus spp. below 1 CFU/m 3 may be sufficient to cause infection in high-risk patients and new group of patients without classical risk factor of neutropenia like chronic pulmonary disease, critically ill, and HIV are emerging, such high concentrations (average count of both areas 100 CFU/mm 3) may potentially increase the risk for the development of invasive aspergillosis in patients attending our hospital.[9],[10] Prospective studies linking environmental source with patient isolate following detection of case of invasive aspergillosis in patients admitted at our hospital are required to validate this finding.

A study by Sautour et al. revealed that fungal concentration in hospital air was highest in summers while Tormo-Molina et al. showed that it was highest in spring autumn.[11],[12] The observations on the influence of climatic conditions related to the seasons are contradictory especially for the Aspergillus species, Daniau et al. and Goodley et al. do not report seasonal variations.[13],[14],[15] Our findings are consistent to those in the above-mentioned studies, as no significant difference was observed in the fungal load per se as well as distribution of various fungal species in different seasons of the year.[13],[14] This can be explained by the fact that India being a tropical country has ambient temperature and levels of humidity for fungi to maintain in the environment. Contrary to normal belief that the AC areas would have lower mean burden of fungal spore, our study showed that, although lower vis-a-vis the non-AC areas, the AC areas had high fungal spore levels. The AC systems provide a likely environment for the colonisation and multiplication of airborne fungi, which can remain in the environment as contaminant microorganisms and can infect the patients in ICUs.This finding suggests the need for periodical maintenance and disinfection of the AC systems to prevent the colonisation and dissemination of fungi.


The present study supplements the current knowledge on hospital aeromycoflora by demonstrating a high fungal spore burden in hospital air with predominance of Aspergillus spp. regardless of AC or not. Further steps to reduce the same and link cases of invasive aspergillosis with environmental source need to be undertaken.

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Conflicts of interest

There are no conflicts of interest.


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