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Year : 2014  |  Volume : 3  |  Issue : 1  |  Page : 5-8

Operating theaters as a source of nosocomial infection: A systematic review

1 Department of Medical Microbiology and Immunology, Institute of Bio-Medical Sciences, College of Health Sciences, Mekelle University, Mek'ele, Ethiopia
2 Department of Human Anatomy, Institute of Bio-Medical Sciences, College of Health Sciences, Mekelle University, Mek'ele, Ethiopia

Date of Web Publication9-Apr-2014

Correspondence Address:
Tewelde Tesfaye Gebremariam
Department of Medical Microbiology and Immunology, Institute of Bio-Medical Sciences, College of Health Sciences, Mekelle University, P. O. Box 1871, Mek'ele
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/2278-0521.130196

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Introduction: Microbial contamination of operating theaters (OTs) is a major cause of nosocomial infections (NIs). Purpose: Thus, the purpose of this systematic review was to determine the degree of contamination present on OTs and to evaluate the methodological quality of this evidence. Materials and Methods: Published studies from December 2000 to December 2012 were identified in nine major databases. Methodological quality was evaluated using a quantitative critical appraisal tool. Data were extracted and analyzed using four major outcome measures. Results and Conclusion: A total of 45 studies were identified investigating the levels of microbial contamination on OTs; of which 26 were included in the review. The included studies reported that 51.3% of all sampled air/articles/surfaces of OTs were contaminated. However, the majority of microbial contamination and hence any risk of acquiring a NIs can be reduced substantially by implementing the infection control measures. Further research is also required on the role of OTs in NIs.

Keywords: Cross-infection, microbial contamination, nosocomial infection, operating theater

How to cite this article:
Gebremariam TT, Declaro MF. Operating theaters as a source of nosocomial infection: A systematic review. Saudi J Health Sci 2014;3:5-8

How to cite this URL:
Gebremariam TT, Declaro MF. Operating theaters as a source of nosocomial infection: A systematic review. Saudi J Health Sci [serial online] 2014 [cited 2019 Dec 16];3:5-8. Available from: http://www.saudijhealthsci.org/text.asp?2014/3/1/5/130196

  Introduction Top

Microbial contamination of operating theaters (OTs) is a major cause of nosocomial infections (NIs). [1],[2],[3],[4] It is considered to be a risk factor for surgical site infections (SSIs). [2],[4],[5] SSI delays wound healing, prolongs hospitalization, increases morbidity and the overall costs. [6],[7],[8]

Multiple reservoirs have been reported as being responsible for the contamination of the OT, including unfiltered air, ventilation systems and antiseptic solutions, drainage of the wounds, transportation of patients and collection bags, surgical team, extent of indoor traffic, theater gown, foot wares, gloves and hands, use of inadequately sterilized equipment, contaminated environment and grossly contaminated surfaces. [2],[4],[9],[10],[11],[12],[13],[14] The impact of these sources on the degree of microbial contamination differs, depending on the numbers of pathogens involved. Staphylococcus aureus and the coagulase negative staphylococci (CoNS), for example, are the major pathogens associated with infection of implantable biomedical devices. [9]

The clinical implication of microbial contamination in OT is enormous on both the patient and the caring surgical team. [2],[4],[5] Approximately, 10% of all infections can have serious consequences in terms of increased patient mortality, morbidity and length of hospital stay and overall costs. [15] However, it can be prevented through adequate application of infection control practices. Reduction of airborne bacteria in the OT by about 13-fold, for example, would reduce the wound contamination by about 50%. [2] Reduction of microbial contamination depends primarily on improved cleaning and proper disinfection of OT. [2],[4]

The risk of infection from OTs also needs to be viewed in light of current evidence-based practice. Evidence emanating from research of low methodological quality is more likely to over- or underestimates the risk of NI from OTs, giving an inaccurate description of the problem and making the risk of infection from OTs difficult to ascertain. A systematic review provides a standardized critical appraisal of all research in this area and allows recommendations for future research to be made based on shortcomings in the research design and methods of previous studies. Thus, the aim of this systematic review was to determine the degree of contamination present on OTs, to determine, which preventive measures are most successful in reducing the level of contamination on OTs and to evaluate the methodological quality of this evidence.

  Materials and Methods Top

Literature review

A literature search was performed to identify published and unpublished studies between December 2000 and December 2012. Published studies were identified using an initial search of the MedLine Database, Academic Search Elite Database, PubMed, Science Direct, CDC Database, Index Medicus Database, SAGE Database, IDOSI Database and CINAHL. The reference lists and bibliographies of all articles were then cross-checked for additional published and unpublished studies. The following keywords were used separately and combined in all databases and search engines: NI, infection, microbial contamination, contamination, OT, OT air, operating table, operating room lights, anesthesia machine, anesthesia cart, electronic monitor, pulse oximeter machine, automated blood pressure measuring machine, electrocautery machine and surgical clothing. Studies were included in the systematic review if they met the following criteria:

  • Observational studies examining the level of microbial contamination on OT
  • Subjects-air, surfaces and surgical equipments in OT involving exposure to the patient and the operating staff
  • Full-text articles in English, published between December 2000 and December 2012.

Methodological quality assessment

Methodological quality assessment was carried out in two steps. Firstly, each study was ranked according to the hierarchy of evidence. [16] Studies were then reviewed critically using an adapted form of the quantitative appraisal tool. [17] This tool was adapted to make criteria specific to microbiological techniques. This included a section on microbiological methods such as times and temperatures relevant to incubation procedures, times and days of the week when the material was sampled, method used to collect samples (swabbing or plating) and the time lapse before collected samples were incubated. These criteria were included to evaluate the use of standard and therefore valid and reliable, microbiological techniques in each study. The critical appraisal tool assessed nine domains; including study purpose, study design, sample and methodology and data analysis. Each of the nine domains had one or more criteria. All criteria answered with a "yes" scored the full number of points while criteria answered with a "no" or which were not addressed scored zero. The maximum score that could be reached was 14 for observational studies.


To ensure the reliability of the scoring system, 10 papers selected at random were reviewed independently by two assessors. Following this review, a Pearson's correlation coefficient was calculated demonstrating 96% agreement between the two assessors (R = 0.98). A two-tailed paired t-test returned a P value of 0.34 (t = 1), demonstrating no significant difference between the two assessors and hence the absence of any systematic bias in scoring.

Data extraction

A total of 45 studies were identified investigating the levels of microbial contamination on OTs; of which 26 were included in the review. Data were extracted from the articles and categorized using the following four outcome measures: The total percentage of sampled air/surfaces/articles contaminated with micro-organisms; the number of colony-forming units (CFUs) present on sampled air/surfaces/articles; the number of different organisms present on sampled air/surfaces/articles; and the percentage of organisms identified as S. aureus. Data was then analyzed by calculating the pooled mean and range for each outcome measure.

  Results and Discussion Top

Microbial contamination of the OT had continued to increase the prevalence of NI. [2],[3],[4] Microorganisms that cause infections in OT include bacteria, fungi and viruses. [18] Some bacterial strains such as S. aureus, Staphylococcus epidermidis,  Escherichia More Details coli and Pseudomonas aeruginosa have a greater propensity to cause contamination in OTs. [3] Pathogenic microbes including multidrug-resistant Mycobacterium tuberculosis, Legionella, methicillin-resistant S. aureus and Aspergillus spores can be also suspended in the air, enabling disease to be transmitted easily. [19] S. aureus and β-hemolytic Streptococci have also been linked to airborne transmission in OT. [13]

The studies included in this review reported a significant proportion of air/articles/surfaces of OTs to be heavily contaminated with micro-organisms. Studies reported that up to 80% of sampled air/articles/surfaces of OTs were contaminated, with a pooled mean of 51.3% and a range of 32.9-84.0%. Only two studies reported the percentage of contaminated air/articles/surfaces OTs to be <50.0%. [3],[20] The number of CFUs present on sampled air/articles/surfaces of OTs ranged from 3.3 to >145.0, with a pooled mean of 35.3 CFUs/sample. [14],[21],[22],[23] In addition, 27.8% of all organisms were identified as the potentially pathogenic S. aureus and of these isolates, 10% were multidrug resistant. In addition, significant numbers of other potential pathogens, including CoNS, P. aeruginosa and Bacillus spp., were identified.

S. aureus was isolated from all the air samples obtained from the various OTs except ear, nose and throat (ENT). Surgical OT showed 62.5% prevalence of S. aureus in the air. CoNS were isolated from the air sample from all the OT with the lowest prevalence in eye (50%) and urology (48%). The rest of the air samples showed growth of CoNS. Bacillus sp. was present in the air of the various OTs with the lowest prevalence being 60% in the urology OT, 62.5% in the surgical OT and 66.6% in the orthopedics OT. Air samples obtained from ENT, eye and gynae and obstetrics showed 100% positivity for Bacillus spp. S. pneumoniae was isolated from the eye (50%) and surgical OT (62.5%) only.

Bacillus was the predominant organism isolated from various surfaces and articles. It was present in 77% of the surfaces sampled from the ENT OT, 42.6% from surgical OT surfaces and 30.8% of the surfaces/articles from the orthopedic OT. Urology (27.3%), eye (15%) and neurosurgery (10%) OT surfaces and articles were found to be contaminated with Bacillus spp., S. aureus was pre-dominantly isolated from urology (40.9%) and neurosurgery (40%) articles/surfaces, whereas the surgical OT instruments/surfaces growth of coagulase negative Staphylococcus (53.7%). S. pneumonae and other Streptococcus sp. were isolated with equal frequency from ENT and eye OT, 7.7% and 5% respectively. However, S. pneumonae was isolated in a higher percentage (14.8%) from the surgical OT when compared to with other Streptococcus species (5.6%). Pseudomonas, E. coli and Klebsiella were the Gram-negative rods isolated. Orthopedics and urology OT showed the highest rate of contamination (23.1% and 22.7% respectively). Aspergillus was found in surgery (13%), urology (9.1%), eye (5%) and neurosurgery (5%) OTs. The pooled means and ranges for each outcome measure evaluated are presented in [Table 1].
Table 1: Pooled range and mean for levels of contamination of operating theatres

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The results indicate that three factors need to be considered. First, some bacterial strains such as S. aureus, S. epidermidis, E. coli and P. aeruginosa have a greater propensity to cause contamination in OTs, so extensive infection control practices are necessary to prevent or contain these pathogens. Second, the social level of incoming patients reflects the individual patient risk, which must be investigated and modified whenever possible. Patient should be prepared for operation and appropriate skin antiseptic should be used on the operation sites; the patient should also be considered for preoperative antibiotic prophylaxis. Bowel preparation, if appropriate, should be carried out. Third, careful attention to the theater operating environment is important, especially to avoid airborne transmission of bacteria and transmission to the water supply and food; surgical expertise and theater discipline are essential components against surgical sepsis. [3]

Infection control measures in operating theaters

Well implemented infection control should be at the heart of good hospital management. [24] The importance of infection control must also be recognized by the chief executive of the hospital and clinical user groups. In addition, infection control team (ICT) must be established and it is vital that good working relationships are built up between the ICT team. [25] Moreover; the ICT teams need the authority to influence the process. [1],[22],[25],[26]

Preventive measures aimed at minimizing the introduction, generation and retention of particles inside the OT are recommended. [22] It has been estimated that a 13-fold reduction in airborne bacteria in the OTs would reduce wound contamination by around 50%. [14] Moreover, prevention SSI involves identifying and controlling potential sources of microbial contamination. [2],[15] Foot traffic of the OTs should be reduced, the ventilation system should also be improved and appropriate educational intervention on routine cleaning practices should be provided for sanitary personnel. [1],[13],[14],[27] This restricts the movement of airborne contaminants, such as pathogens carried and shed by people and objects. [1] Patient should also be prepared for operation and appropriate skin antiseptic should be used on the operation sites; the introduction of prophylactic antibiotics use also provides additional protection against infection. [3] Similarly, staff and students should be trained on the need for high level of high hygiene. [4] The barrier properties of the traditional surgical mask break down rapidly, enhancing pre-operative nasal shedding. Therefore, strategies that would limit extraneous exposure of these devices to OT air before insertion should be considered by members of the surgical team. Surgical mask should be changed at an appropriate interval (60-90 min), especially if members of the surgical team are symptomatic for rhinorrhea. [9],[14] In general, the policy to reduce microbial contamination in OT is based on a behavioral and systemic approach. In a behavioral approach, preventive measures focus on reducing the number of airborne particles in the operating room through disciplinary measures. Simple and cheap measures include limiting the number of personnel in the operating room and restricting the movements of personnel in the OT to a minimum as it has been shown that increased activity enhances the dispersion of bacteria. [20]

  Conclusion Top

Current evidences indicated that microbial contamination of OTs is a major risk factor for NIs. However, it can be reduced substantially through implantation of the infection control measures. This systematic review calls for further research on the role OTs in NIs.

  References Top

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23.Napoli C, Tafuri S, Montenegro L, Cassano M, Notarnicola A, Lattarulo S, et al. Air sampling methods to evaluate microbial contamination in operating theatres: Results of a comparative study in an orthopaedics department. J Hosp Infect 2012;80:128-32.  Back to cited text no. 23
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