Abstract
Objective
To investigate the quality of indoor air of different wards and units of Olabisi Onabanjo University Teaching Hospital, Sagamu, to ascertain their contribution to infection rate in the hospital.
Methods
The microbial quality of indoor air of nine wards/units of Olabisi Onabanjo University Teaching Hospital, Sagamu, Nigeria was conducted. Sedimentation technique using open Petri-dishes containing different culture media was employed and samplings were done twice daily, one in the morning shortly after cleaning and before influx of people/patients into the wards/units and the other in the evening when a lot of activities would have taken place in these wards. Isolates were identified according to standard methods.
Results
Results showed that there was a statistically significant difference (χ2 = 6.016 7) in the bacteria population of the different sampling time whereas it was not so for fungi population (χ2 = 0.285 7). Male medical ward (MMW) and male surgical general (MSG) recorded the highest bacterial and fungal growth while the operating theatre (OT) was almost free of microbial burden. The bacteria isolates were Staphylococcus aureus, Klebsiella sp., Bacillus cereus, Bacillus subtilis, Streptococcus pyogenes and Serratia marscences while the fungi isolates included Aspergillus flavus, Penicillium sp., Fusarium sp., Candida albicans and Alternaria sp. Staphylococcus aureus was the predominantly isolated bacterium while Penicillium sp. was the most isolated fungus.
Conclusions
Though most of the microbial isolates were potential and or opportunistic pathogens, there was no correlation between the isolates in this study and the surveillance report of nosocomial infection during the period of study, hence the contribution of the indoor air cannot be established. From the reduction noticed in the morning samples, stringent measures such as proper disinfection and regular cleaning, restriction of patient relatives' movement in and out of the wards/units need to be enforced so as to improve the quality of indoor air of our hospital wards/units.
Keywords: Indoor air, OOUTH, Open-plate technique, Nosocomial infections, Staphylococcus aureus, Microbiological assessment, Microbial quality, Bacterial isolate, Fungal isolate, Opportunistic pathogen, Nosocomial infection, Infection rate, Microbial isolate, Penicillium sp., Sedimentation technique
1. Introduction
Patients are primarily admitted into hospital wards for proper management of their ailments, but while on admission some patients acquire other ailments than the one they were admitted for. These are called hospital associated infections (nosocomial infections) which can result from contact with a carrier directly or indirectly through inanimate objects or air.
The quality of indoor air in terms of microbial contamination in a given space at a given time period is said to be determined by the quality of air entering the space, the umber of occupants in the space, their physical activities and resultant aerosol generation, human traffic and the degree of ventilation[1]–[3]. Dust, which is a good vehicle of airborne contamination, may arise from human activities, such as sweeping, movement, waving of handkerchief and bed making. Sneezing has been described as the most vigorous mechanism of generating millions of droplet into the environment. While the larger droplets fall to the ground or on nearby objects, the smaller ones are rapidly evaporated to their non-volatile residual forms and remain suspended as droplet nuclei[4].
Measures often taken in preventing nosocomial infections include effective use of antiseptics, disinfectants, adequate cleaning, sterilization and isolation of patients with highly infectious diseases[5].
However, less attention is paid to indoor air as been a probable contributing factor to hospital acquired infections. Ishida et al[6] reported that airborne bacteria in the hospital environment have been a major source of post-operative infection and a serious problem in the Intensive Care Unit[7]. Many of these isolates (bacteria) are shown to be resistant to common antiseptics used in hospitals[8].
Organisms that are often associated with hospital acquired infections are Staphylococcus aureus, Micrococcus sp., Pseudomonas sp., Proteus sp., Escherichia coli, Enterobacter, Bacillus cereus, Cladosporium sp., Aspergillus sp., and viruses[9],[10]. Pseudomonas aeruginosa has been particularly incriminated in nosocomial infection because of its intrinsic resistance to most antibiotics and its ability to survive and multiply at low temperatures and in disinfectant solutions[11]. Regular microbiological surveillance of the different hospital units, patients' surveillance by the hospital's Infection Control Unit, formulation of antibiotic policy and recommendation to hospital management for implementation of findings will go a long way to reduce nosocomial infections.
This study therefore was aimed at investigating the quality of indoor air of different wards and units of Olabisi Onabanjo University Teaching Hospital (OOUTH), Sagamu, to ascertain their contribution to infection rate in the hospital. It will also provide a baseline information on the quality of indoor air which before now was not available.
2. Materials and methods
2.1. Study area
OOUTH, Sagamu, is a tertiary health institution located in the Southwestern part of Nigeria. It has two hundred and forty bed spaces and this was the study area. Nine wards/units were used for sample collection and these included male medical ward (MMW), female medical ward (FMW), children's ward (CHW), neonatal unit (NNU), male surgical specialty (MSS), male surgical general (MSG), female surgical ward (FSW), operating theatre (OT) and accident & emergency unit (A&E). The study was carried out between May and June, 2010.
2.2. Sampling procedure
Sedimentation technique using open Petri dishes containing different culture media was used[12]. Three plates of each medium were distributed at different parts of wards/units examined. The samplings were done at the morning hours (8.00–10.00 am) and evening periods (4.00–6.00 pm). The plates containing the culture media (blood agar and Sabouraud dextrose agar) were exposed and allowed to stay for 20 minutes, after which the plates were covered and transferred to the hospital's Microbiology Laboratory Unit for incubation. The blood agar plates were incubated at 37 °C for 48 hours while the Saboraud dextrose agar plates were incubated for 3–5 days at 28 °C. The total numbers of colony forming units (cfu) were enumerated. The identification of the isolates was done according to standard procedures[13],[14].
2.3. Statistical analysis
The data thus generated were analyzed by simple mean value, percentage and test of significance using Chi-square[15].
3. Results
3.1. Bacteria distribution
A total number of nine wards/units were studied. The bacterial population was higher (56.83%) among the evening samples than the morning samples (43.17%). MSG was the most contaminated among the wards during the morning sampling (26.67%) while 31.65% was recorded in MMW in the evening samples, thus making it the most contaminated ward for the evening session. NNU, OT and A&E had low bacterial contamination in their indoor air (Table 1).
Table 1. Number and percentage of airborne bacterial population in air of the sampled wards/units (cfu).
| Study area | Sampling time |
|
| Morning (8.00–10.00 am) | Evening (4.00–6.00 pm) | |
| MMW | 15 (25.00) | 25 (31.65) |
| FMW | 5 (8.33) | 8 (10.13) |
| CHW | 5 (8.33) | 11 (13.92) |
| NNU | 2 (3.33) | 2 (2.53) |
| MSS | 4 (6.67) | 3 (3.80) |
| MSG | 16 (26.67) | 16 (20.25) |
| FSW | 11 (18.33) | 12 (15.19) |
| OT | 1 (1.67) | – |
| A&E | 1 (1.67) | 2 (2.53) |
| Total | 60 (100.00) | 79 (100.00) |
3.2. Fungi distribution
Plates from the nine ward/units for evening samples yielded 16 cfu of fungi as against 14 from the morning samples. The distribution showed that MSG had the highest growth (28.57%) in the morning session whereas the medical wards recorded the highest growth in the evening session with 31.25% and 25.00% for MMW and FMW, respectively. MSS and OT had no fungal growth while NNU and A&E yielded one and two cfu of fungi, respectively as shown in Table 2.
Table 2. Number and percentage of airborne fungal population in air of the sampled units (cfu).
| Study area | Sampling time |
|
| Morning (8.00–10.00 am) | Evening (4.00–6.00 pm) | |
| MMW | 1 (7.14) | 5 (31.25) |
| FMW | 3 (21.43) | 4 (25.00) |
| CW | 3 (21.43) | 2 (12.50) |
| NNU | 1 (7.14) | – |
| MSS | – | – |
| MSG | 4 (28.57) | 2 (12.50) |
| FSW | 2 (14.29) | 1 (6.25) |
| OT | – | – |
| A & E | – | 2 (12.50) |
| Total | 14 (100.00) | 16 (100.00) |
3.3. Frequency of isolation
Staphylococcus aureus was the predominantly isolated bacteria, being isolated in all the six plates used in MMW and found in all the wards/units sampled. This was closely followed by Klebsiella sp. and Serratia marscences was isolated only in MSG and the only bacteria isolated in OT was Staphylococcus aureus. The A&E had a cfu of Staphylococcus aureus and Bacillus subtilis as shown in Table 3. Penicillium sp. was isolated in six of the nine wards/units sampled with the highest frequency in MMW. Aspergillus flavus was isolated in 4 wards/units of the sampled areas of the hospital. Candida albicans was isolated in the paediatric sections of the hospitals i.e. CHW and NNU. There was no fungus isolated from OT.
Table 3. Frequency of occurrence of isolates from the sampled units.
| Isolates | FMW | MMW | CHW | NNU | MSS | MSG | FSW | OT | A&E |
| Staphylococcus aureus | 2 | 6 | 1 | 1 | 2 | 4 | 3 | 1 | 1 |
| Bacillus cereus | 1 | 5 | 2 | – | – | 2 | 2 | – | – |
| Klebsiella sp. | 5 | 6 | 2 | 1 | 1 | 6 | 3 | – | – |
| Serratia marscences | – | – | – | – | – | 2 | – | – | – |
| Bacillus subtils | – | 6 | 5 | – | – | 1 | – | – | 1 |
| Streptococcus sp. | – | 2 | 1 | – | 1 | 1 | 1 | – | – |
| Aspergillus flavus | 1 | 2 | 1 | – | – | 1 | – | – | – |
| Penicillium sp. | 2 | 2 | 1 | – | – | 2 | 1 | – | 1 |
| Fusarium sp. | – | 1 | – | – | – | – | 1 | – | 1 |
| Candida albicans | – | – | 1 | 1 | – | – | – | – | – |
| Alternaria sp. | 1 | 1 | – | – | – | 1 | – | – | – |
The frequency distribution of the mostly isolated bacterium (Staphylococcus aureus) and fungus (Penicillium sp.) was presented in Figure 1.
Figure 1. Frequency of occurrence of Staphylococcus aureus and Penicillium sp. from the sampled units.
4. Discussion
Hospital associated infections have been linked with many factors among which is the microbial quality of the indoor air of different wards and units of each hospital[1]. This type of infection occurs in 5% of all acute care hospitalization in the United State and has been reported to be responsible for the death of one out of every five thousand patients attending an American hospital[17]. In Nigeria, the rate of nosocomial infection ranges between 2.7%–3.8%[18],[19], but 4.0% at OOUTH before this study. This calls for looking at every possible measure to control the rise including (among other investigations) examining the quality of indoor air of the hospital wards and units.
It was on this background that a qualitative study of the different hospital wards/units of OOUTH was carried out. This study revealed that MMW recorded the highest indoor airborne bacteria population and closely followed by MSG. At the time of this study, the two wards were at their maximum capacity, this invariably will attract more patient relative in and out of these wards thereby increasing the shedding of bacteria and agitation of air. However, in a similar study by Ekhaise et al[1], A&E recorded the highest airborne bacterial and fungal population, this is at variance with this study in which A&E and OT were the least burdened units of the hospital. The structural design and regular scrubbing of the OT and restriction of movement in and out of it might be responsible for the low bacteria burden of its indoor air. No fungal element was isolated from the OT and MSS. MSW and MSG again recorded the highest indoor airborne fungal population.
The microbial isolates included six bacteria and five fungi which are Staphylococcus aureus, Bacillus cereus, Klebsiella sp., Serratia merscences, Bacillus subtilis, Streptococcus pyogenes for the bacteria isolates while the fungi isolates includes Aspergillus flavus, Penicillium sp., Fusarium sp., Candida albicans and Alternaria sp. Some of these clinical isolates have been reported by earlier researchers[8],[9],[20],[21]. Staphylococcus aureus as the most frequently isolated bacterium from this study has been incriminated in various diseases such as post operative infections, urinary tract infections, skin infections, respiratory infections and food poisoning[22],[23]. Proper control measures such as increase in hygiene are required to combat infections by Staphylococcus aureus in these hospital wards and units. Bacillus sp. are spore forming organisms that can survive for longer period of time and can cause serious medical problems, hence proper program for eliminating it must be put in place. Klebsiella sp. and Streptococcus pyogenes are associated with urinary tract infection among catheterized patients and immuno-compromised patients[24],[25], though not isolated from any of the patients on admission during the study, (surveillance report) their isolation in this study calls for more adequate control measures. The isolation of Aspergillus flavus, a medically important fungus for aflatoxin production, a neurotoxigenic substance, and which can also cause lung infection should not be overlooked just as Candida albicans which are isolated from the neonatal wards where they can cause neonatal conjunctivitis. Improving hygiene might suffice in the affected wards/units.
The monthly surveillance of the hospital's Infection Control Unit for the months of this study showed that two hospital associated infections are caused by Pseudomonas aeruginosa in MMW and FMW among patients with indwelling catheter. Since no Pseudomonas sp. was isolated in this study, the role of contaminated indoor air could not be correlated in these infections. However, since the isolated bacteria and fungi could be pathogenic if contact is established with patients, it is pertinent that their presence should be controlled.
Regular surveillance, cleaning and restriction of patients relative might be among the strict measures necessary to reduce or totally eliminate the microbial load of indoor air of this hospital wards and units.
Acknowledgments
The authors are grateful to the staff of the Infection Control Unit of the Hospital and the Medical Record Unit for the supply of necessary information required for the completion of this study.
Footnotes
Conflict of interest statement: We declare that we have no conflict of interest.
References
- 1.Ekhaise FO, Isitor EE, Idehen O, Emogbene OA. Airborne microflora in the atmosphere of an hospital environment of University of Benin Teaching Hospital (UBTH), Benin City, Nigeria. World J Agric Sci. 2010;6(2):166–170. [Google Scholar]
- 2.Adebolu TT, Vhriterhire KJ. Survey of the microbial flora of the Ondo State Specialist Hospital Environment, Akure, Nigeria. Niger J Microbiol. 2002;16(112):91–94. [Google Scholar]
- 3.Mitchell ES, Harley MP, Emelor RA. Environmental microbiology. New Jersey: John Wiley and Sons, Inc; 1992. pp. 110–125. [Google Scholar]
- 4.Haley RW, Culver DH, White JW, Morgan WM, Emori TG. The nationwide nosocomial infection rate: a new need for vital statistics. Am J Epidemiol. 1985;121:159–167. doi: 10.1093/oxfordjournals.aje.a113988. [DOI] [PubMed] [Google Scholar]
- 5.Zaidi M, Angulo M, Stifuentes-Osomio J. Disinfection and sterilization practices in Mexico. J Hosp Infect. 1995;31:25–32. doi: 10.1016/0195-6701(95)90080-2. [DOI] [PubMed] [Google Scholar]
- 6.Ishida T, Nakano K, Nakatani H, Gomi A. Bacteriological evaluation of cardiac surgery environment accompanying hospital relocation. Surg Today. 2006;36:504–507. doi: 10.1007/s00595-006-3178-9. [DOI] [PubMed] [Google Scholar]
- 7.Newman MJ. Neonatal intensive care unit: reservoir of nosocomial pathogens. West Afr J Med. 2002;21:310–312. doi: 10.4314/wajm.v21i4.28007. [DOI] [PubMed] [Google Scholar]
- 8.Yagoub SO, Agbash AE. Isolation of potential pathogenic bacteria from the air of hospital-delivery and nursing rooms. J Appl Sci. 2010;10(11):1011–1014. [Google Scholar]
- 9.Ekhaise FO, Ighosewe OU, Ajakpori OD. Hospital indoor airborne microflora in private and government owned hospitals in Benin City, Nigeria. World J Med Sci. 2008;3(1):34–38. [Google Scholar]
- 10.Abdel-Hady H, Hawas S, El-Daker M, El-Kady R. Extended spectrum beta lactmase producing Klebsiella pneumoniae in neonatal intensive care unit. J Perinatol. 2007;74:627–630. doi: 10.1038/jp.2008.73. [DOI] [PubMed] [Google Scholar]
- 11.Ohsaki Y, Koyano S, Tachibana M, Shibukawa K, Kuroki M, Yoshida I, et al. et al. Undetected Bacillus pseudo-outbreak after renovation work in a teaching hospital. J Infect. 2007;54:617–622. doi: 10.1016/j.jinf.2006.10.049. [DOI] [PubMed] [Google Scholar]
- 12.Augustowska M, Dutkiewicz J. Variability of airborne microflora in a hospital ward within a period of one year. Ann Agric Environ Med. 2006;13:99–106. [PubMed] [Google Scholar]
- 13.Cheesbrough M. Medical laboratory manual for tropical countries. 2nd ed. Cambridge, UK: University Press Cambridge; 1991. pp. 508–511. [Google Scholar]
- 14.Rajash B, Rattan LI. Essentials of medical microbiology-medical mycology. 4th ed. New Delhi: Jayppee Brothers Medical Publishers; 2008. pp. 415–439. [Google Scholar]
- 15.Sarmukaddam SB. Fundamentals of biostatistics-categorical data analysis. 1st ed. New Delhi: Jaypee Brothers Medical Publishers (P) Ltd; 2006. pp. 106–121. [Google Scholar]
- 16.National Nosocomial Infections Surveillance (NNIS) system National noocomial infections surveillance system report, data summary from October 1986–April 1998. Am J Infect Control. 1998;26:522–533. doi: 10.1016/s0196-6553(98)70026-4. [DOI] [PubMed] [Google Scholar]
- 17.Putsept E. Modern hospital. New York: Apen System Cooperation; 1981. p. 426. [Google Scholar]
- 18.Kesah CN, Egri-Okwaji MTC, Odugbemi TO, Iroha EO. Bacteria associated with nosocomial infection and their antimicrobial resistance pattern in pediatric patients in a tertiary health institution. J Med Med Sci. 1999;1:6–13. [Google Scholar]
- 19.Onipede AO, Oluyede CO, Aboderin AO, Zailami SB, Adedosu AM, Oyelese AO, et al. et al. A survey of hospital acquired infection in Obafemi Awolowo University Teaching Hospital, Ile-Ife. Afr J Clin Exp Microbiol. 2004;5:108–118. [Google Scholar]
- 20.Tambekar DH, Gulhane PB, Bhokare DD. Studies on environmental monitoring of microbial air flora in the hospitals. J Med Sci. 2007;7:67–73. [Google Scholar]
- 21.Jaffal AA, Nsanze H, Benar A, Ameen AS, Banat IM, Moghett AA. Hospital airborne microbial pollution in a desert country. Environ Int. 1997;23(20):67–172. [Google Scholar]
- 22.Murray PR, Baron EJ, Pfaller MA, Tenover FC, Yolken RH. Manual of clinical microbiology. 6th ed. Washington, DC: American Society of Microbiology; 1995. pp. 282–293. [Google Scholar]
- 23.Buchanan RE, Gibbons NE. Bergey's manual of determinative bacteriology. 8th ed. Baltimore: William and Wilken; 1974. p. 1042. [Google Scholar]
- 24.Oni AA, Mba GA, Ogunkunle MO, Shittu OB, Bakare RA. Nosocomial infections: urinary tract infection in patients with indwelling urinary catheter. Afr J Clin Exp Microbiol. 2003;4:63–71. [Google Scholar]
- 25.Odimayo MS, Nwabuisi S, Adegboro B. Hospital acquired infections in Ilorin, Nigeria. Trop J Health Sci. 2008;15(1):49–54. [Google Scholar]