Radiographic Equipment and Accessories as a Potential Source of Nosocomial Infection ()
1. Introduction
Providing adequate infection control measures in hospitals is crucial to preventing and reducing infectious disease spread, to ensure the safety of patients, staff, and the environment when implemented effectively. Nosocomial infections (NIs) are infections acquired by patients during their hospital stay or that were not present or incubating at the time of admission and an infection that develops after discharge, in addition to infection contracted by a healthcare worker, both through direct contact between patients and inadequately disinfected medical devices and accessories that are contaminated with body secretions or between patients and staff can spread nosocomial pathogens [1]. Both developed and developing countries report NI rates of 7% and 10%, respectively [1].
There is a 13-fold increase in medical device-associated infections in low- and middle-income countries compared to those in high-income countries [2]. Multiple studies have been conducted to determine the incidence of device-associated NIs (DA-NIs) in Saudi Arabia [3] [4], at King Fahad National Guard Hospital in Riyadh, Balkhy et al. demonstrated that 45 (8%) of 562 patients developed NI [3]. They also found that central line-associated bloodstream infections (CLABSIs) were the most commonly reported NI (31.1%), followed by ventilator-associated pneumonia (VAP) (28.9%) and catheter-associated urinary tract infections (CAUTIs) (24.4%). Further, they reported that most NIs occurred in ICUs [3]. In a study of 12 reference hospitals of the Ministry of Health in the Kingdom of Saudi Arabia, Gaid et al. showed that VAP was the most frequently reported DA-NI (57.4%), followed by CAUTIs (28.4%) and CLABSIs (14.2%) in 13492 patients [5]. Moreover, Tawfiq et al. reported that CAUTIs were the most common DA-NIs (42.2%) followed by CLABSIs (38.5%) and VAP (19.3%) in adult ICUs of the Saudi Aramco Medical Services Organization [6].
Other studies have shown that NIs are particularly high in certain areas of hospitals, such as radiology departments, where there is interaction with large numbers of patients from all areas of the hospital [6]. Studies have confirmed that radiographic equipment, accessories and procedures can cause the spread of NIs [7].
Healthcare services worldwide are also affected by an escalating financial burden associated with increased patient morbidity and mortality due to healthcare-associated infections [8]. Approximately a decade ago, the UK National Health Service’s annual expenditure on NIs was one million pounds sterling [9]. During the same period, 1.7 million hospitalized patients in the United States of America developed NIs, resulting in 98,987 deaths [10].
The radiology department provides imaging services to patients from different departments of the hospital. The radiology department has been documented to facilitate the transmission of several healthcare-associated pathogens, including Vancomycin-Resistant Enterococci, Clostridium difficile, Acinetobacter species, Methicillin Resistant Staphylococcus aureus (MRSA) and Norovirus [11]. Therefore, radiology contributes significantly to the potential spread of nosocomial infections.
This study was conducted to determine if radiographic equipment and accessories increased the risk of contracting an NI, to identify the nosocomial bacteria most commonly found on X-ray units in four departments and to assess the effectiveness of routine daily disinfection practices on the control of microorganisms in X-ray units. Findings from this study will help hospital infection control departments in reviewing their hygienic improvement plans.
2. Methods
All X-ray equipment and accessories from four diagnostic imaging departments at different hospitals in Riyadh were swabbed. Accessories, such as X-ray couches, chest stands, X-ray cassettes/imaging plates, handles of X-ray tube heads, control panels, and/or exposure buttons, were first swabbed with sterile swab sticks. The swab sticks and swabbed surfaces were dry; therefore, they were moistened with a nutrient broth. Then, the entire surface of the radiographic apparatus and accessories were swabbed with a rolling motion. Swabs were taken three times a day at the same time (morning, noon, and evening) for five consecutive days. The swabs were transported to the microbiology laboratory for culture and identification using standard biochemical tests. Samples collected at different times of the day were compared using paired t-tests [12]. All statistical analyses were performed using SPSS for Windows software (version 16.0; SPSS Inc., Chicago, IL, USA), and P ≤ 0.05 was considered statistically significant. The study protocol was approved by the King Saud University Scientific Committee (ethics number: CAMS 063-3839).
3. Results
A total of 180 swab samples were collected from X-ray equipment and accessories in four diagnostic imaging departments. Bacteria were isolated from 65 swabs (36.1% swab samples); three bacterial isolates (4.6%) were obtained in the morning, 16 (24.6%) at midday, and 46 (70.7%) in the evening (Table 1).
Table 1. Timing of bacterial isolation and percentages.
|
Morning |
Midday |
Evening |
Total |
| Cultured isolates, n |
03 |
16 |
46 |
65 |
| Isolates, % |
04.6 % |
24.6 % |
70.7 % |
The bacteria isolated from four different diagnostic imaging departments were:
From the first department, only Staphylococcus aureus and Staphylococcus epidermidis were isolated. From the second department Escherichia coli, Staphylococcus aureus, and Staphylococcus epidermidis, were isolated. From the third and fourth department Escherichia coli, Staphylococcus aureus, Staphylococcus epidermidis and Klebsiella spp. were isolated.
The number of bacterial isolates in the samples from the fourth and third diagnostic imaging departments (n = 23 and n = 19, respectively) was higher than the numbers of bacterial isolates in samples from the first and second diagnostic imaging departments (n = 12 and n = 11, respectively). E. coli was the most commonly isolated bacteria (n = 34; 52.3%) followed by S. aureus (n = 20; 30.8%), S. epidermidis (n = 6; 9.3%), and Klebsiella spp. (n = 5; 7.7%; Table 2).
Table 2. Bacterial isolates and their prevalence.
| Bacterium |
Prevalence, n |
Percentage |
| Escherichia coli |
34 |
52.3 |
| Staphylococcus aureus |
20 |
30.8 |
| Staphylococcus epidermidis |
6 |
9.3 |
| Klebsiella spp. |
5 |
7.7 |
There were significant differences in the prevalence of bacterial isolates between morning and midday samples, midday and evening samples, and morning and evening samples at all four hospitals, (P < 0.001) (Table 3).
Table 3. Comparison of the prevalence of bacterial isolates collected at different times in four radiology departments.
|
Comparison |
Paired t-test (P-value) |
| All hospitals |
Morning vs midday |
α = 0.000 - significant difference |
| Midday vs evening |
α = 0.000 - significant difference |
| Morning vs evening |
α = 0.000 - significant difference |
There were no significant differences between the samples collected in the morning and those collected at midday or between those collected at midday and those collected in the evening at hospitals 1 and 4, (P = 0.082, P = 0.719) respectively (Table 4).
Table 4. Comparison of the prevalence of bacterial isolates obtained at different times in four different hospitals.
|
Comparison |
Paired t-test (P-value) |
| Hospital 1 |
Morning - midday |
α = 0.082 - no significant difference |
| Midday - evening |
α = 0.009 - significant difference |
| Morning - evening |
α = 0.000 - significant difference |
| Hospital 2 |
Morning - midday |
No difference at the sample level |
| Midday - evening |
α = 0.000 - significant difference |
| Morning - evening |
α = 0.000 - significant difference |
| Hospital 3 |
Morning - midday |
No difference at the level of sample |
| Midday - evening |
α = 0.000 - significant difference |
| Morning - evening |
α = 0.000 - significant difference |
| Hospital 4 |
Morning - midday |
α = 0.000 - significant difference |
| Midday - evening |
α = 0.719 - no significant difference |
| Morning - evening |
α = 0.000 - significant difference |
| All hospitals |
Morning - midday |
α = 0.000 - significant difference |
| Midday - evening |
α = 0.000 - significant difference |
| Morning - evening |
α = 0.000 - significant difference |
4. Discussion
The radiology department and its equipment are a potential source of NIs including patients; who act as a source of infection and are susceptible to infection, or both [7] [13]. Research has shown that radiology equipment and its accessories are potential sources of pathogens that can cause NIs and are ideal vectors for the transmission of pathologic organisms from one patient to another [14] [15].
The current study confirmed that X-ray equipment and accessories harbor nosocomial bacteria. Additionally, our results showed that 36.1% of samples were contaminated with bacteria. This percentage is consistent with a study conducted by Ochie et al. who reported that the prevalence of bacteria on X-ray equipment and accessories was 47.2% [16]. Findings from the present study demonstrated that E. coli was the most commonly identified micro-organism on X-ray equipment and accessories, followed by S. aureus, S. epidermidis, and Klebsiella spp. Results from a similar study revealed that S. aureus, Klebsiella spp., and S. epidermidis were identified in 142 swabs from X-ray equipment and accessories [16]. Moreover, another study found that mobile X-ray cassettes were colonized with S. aureus, E. coli, S. epidermidis, and Enterobacter aerogenes [17]. It has also been reported that some nosocomial pathogens, such as E. coli, Enterococcus faecalis, and S. aureus, not only survive for long periods on surfaces, but multiply on X-ray cassettes. These pathogens can be transmitted to patients, radiologic technologists, and other health care personnel [18].
Although the above-mentioned microbes colonize only healthy people, they cause most infections that occur in hospitals [1]. E. coli is a commensal bacterium that colonizes the gastrointestinal tract of humans and other mammalian species. Studies have shown that this microorganism can cause many pathologic conditions, including urinary tract infections, septicemia, pneumonia, neonatal meningitis, peritonitis, and gastroenteritis [19].
S. aureus was the second most common bacterium found on the radiographic equipment and accessories in this study. This organism is the most common causative agent of infectious diseases, severe illness, and death in humans [20]. S. aureus is part of the normal flora that colonizes the nose and skin in healthy people; however, in some cases, infection can occur, especially in immunocompromised patients [19]. S. epidermidis and Klebsiella spp. were also isolated in this study. All of these pathogens are a known cause of NIs to most physicians. S. epidermidis and S. aureus are potentially harmful because they colonize the skin as normal flora, but they can invade the body and progress to infection in certain circumstances, such as in immunocompromised patients and those with skin wounds or surgical wounds [21]. Patients who suffer from chronic pneumonia caused by K. pneumoniae or K. oxytoca may visit the radiology department for chest X-ray examinations [22].
MRSA isolates are resistant to the antibiotics used to treat staphylococcal infections. MRSA is a major cause of skin, wound, soft tissue, respiratory, endovascular, and hospital-acquired infections [20] [23]. This organism is transmitted via direct contact, open wounds, and contaminated hands [1] [19] [24]. MRSA was not tested in this study but should be tested in future studies.
In our study, pathogenic bacteria were found on radiographic equipment and accessories, confirming that the sterilization methods used were inadequate. This study also demonstrated a correlation between collection times and bacterial growth. Bacterial counts were higher in the evenings than in the mornings, suggesting that a reasonable decontamination protocol was used after working hours but not between patients.
This finding underscores the importance reducing the potential risk of transfer from equipment to patient. One limitation to this study is its dedication to isolation of bacteria only, further work to include fungal cultures is needed. Given the high demand for diagnostic imaging, we recommend that all radiology departments implement a time-efficient protocol for equipment decontamination.
5. Conclusion
Current infection control protocols may need to be revised, as the results of this study have shown that further efforts are needed to reduce NIs; the frequency of disinfection should be increased to limit the transmission of infections in hospitals. Radiographic equipment and accessories should be properly disinfected immediately before and after use.
Acknowledgements
This research was supported by a grant from the “Research Center of the Female Scientific and Medical Colleges.” Deanship of Scientific Research. King Saud University, Riyadh, Saudi Arabia.
The funding body had no role in the design of the study and collection, analysis, and interpretation of data or in writing the manuscript.
Declarations
Ethics approval and consent to participate:
Experimentation guidelines:
Accessories, such as X-ray couches, chest stands, X-ray cassettes/imaging plates, handles of X-ray tube heads, control panels, and/or exposure buttons, were first swabbed with sterile swab sticks.
The swab sticks and swabbed surfaces were dry; therefore, a nutrient broth was used to moisten them.
The whole surface area of the X-ray equipment and accessories was swabbed using a rolling motion.
Triplicate sample swabs were collected three times daily at the same time (morning, midday, and evening) for five consecutive days.
The swabs were taken to the microbiology laboratory for culture and identification using standard laboratory.
The study protocol was approved by the King Saud University Scientific Committee (ethics number: CAMS 063-3839).
Authors’ Contributions
LFH and EHM devised and designed the study and contributed to both the preliminary manuscript and the final draft. MEZ contributed to the preliminary manuscript and supervised data collection, lab work and analysis and interpreted the data. HTA drafted the first draft. SA and HS contributed to both the preliminary manuscript and the final draft. All the authors read and approved the final version of the manuscript.