Knowledge, Practices, and Nasal Carriage Rate of MRSA Amongst Dental Professionals

Abstract

Objective

Resistance of Staphylococcus aureus (S. aureus) against common antibiotics has been increasing given the rampant use of antibiotics. Methicillin-resistant S. aureus (MRSA) is particularly important because it has been reported to present in hospital-acquired as well as community-acquired infections. Our aim was to study the types and subtypes of MRSA isolated from nasal swabs taken from volunteering dental school students and to assess and analyse the knowledge of dental health care workers (DHCWs) on MRSA and prevention of its infection.

Methods

A total of 100 participants, which included staff, students, and dental auxiliaries, from the School of Dental Sciences, Krishna Institute of Medical Sciences, Deemed to Be University, Karad, India, were included in the study which was conducted from June 2020 to 1 June 2021. All the participants completed a survey and underwent collection of nasal swabs. The samples were cultured and underwent microbiological and molecular analysis for MRSA. The questionnaire was sent out electronically via SurveyMonkey.

Results

Sixty-three percent of the participants were female. The majority were undergraduate students (66%) and younger than 25 years (77%). The prevalence of MRSA in the sample was the MRSA type SCCmec type V (54.8%). The survey reports a lack of knowledge amongst dental students on MRSA and prevention of its infection. The majority (69%) of participants had not heard of MRSA infection and had inadequate knowledge of MRSA infection. Only 29% of the participants think that a healthy person may have MRSA without feeling ill. Eighty-five percent of the participants reported that they have written polices and guidelines to control MRSA. Eighty-five percent of the participants indicated that they are less confident in their knowledge on MRSA infection control protocols, and 94% mentioned that the dental clinics have written guidelines for hand hygiene.

Conclusions

DHCWs have limited knowledge of MRSA infection, emphasising the need for appropriate clinical training. Academic institutions should promote effective infection control training to protect students, faculty, and other employees.

Introduction

Staphylococcus aureus exists as commensals in 25% to 30% of the population and causes infection only on penetrating the skin barrier. The injudicious use of antibiotics has led to gene mutations in the bacteria, leading to multidrug-resistant strains, infections which are potentially life-threatening. Methicillin-resistant S. aureus (MRSA) are strains which display resistance to beta-lactams antibiotics such as oxacillin, penicillin, and amoxicillin. MRSA infections are of key concern from a public health perspective due to their highly infective nature and omnipresence.¹

MRSA was primarily associated with large teaching hospitals. However, recent literature emphasises that they colonise or cause infections in health care personnel and patients in smaller health care facilities, nursing homes, general hospitals, and the community.² Resistance of S. aureus against common antibiotics has been increasing, given the rampant use of antibiotics. MRSA has been reported in hospital-acquired as well as community-acquired infections. This methicillin resistance is conferred by the mecA gene present on staphylococcal cassette chromosome (SCCmec).³

MRSA is a key public health issue on a global scale, and various countries implement multiple strategies to restrict its spread in health care settings. The key to preventing these infections within a dental care facility is adherence to MRSA infection control guidelines in addition to compliance with proper hand hygiene practices, contact isolation, and a strict antibiotic regimen. A major deterrent in the implementation of these strategies is the knowledge of the dental health care team on the dynamism of MRSA and guidelines for its prevention.^4,5

In health care settings, MRSA can spread from patient to patient through human hands, especially in situations when the health care provider performs invasive procedures on multiple patients. It can also be contracted from contaminated surfaces like inanimate objects in infected patients’ rooms or other areas where the patient has been. However, the infection sets in only if the bacteria enter the bloodstream through a skin abrasion. The spread of MRSA can be prevented by having general knowledge of its dynamism and complying with contemporary MRSA prevention guidelines.

Health care workers’ knowledge on health care–acquired infections, including MRSA, and compliance with their prevention guidelines have been considered important measures in stopping the spread of these pathogens in health care institutions.6, 7, 8, 9, 10

A survey of MRSA contamination on the surfaces of the dental operatory and an analysis of MRSA transmission via the dental operatory between patients in a special needs dental care facility reported the presence of MRSA on the surfaces of dental operatory including the air-water syringe and reclining chair, suggesting that MRSA contaminates the surfaces of the dental operatory and therefore the dental operatory should be considered a possible reservoir of MRSA.¹¹

A US Centers for Disease Control and Prevention (CDC)¹² report showed that the proportion of antimicrobial-resistant infections in health care settings has been growing. Reasons range from the most basic, which is the staphylococcal bacteria's resistance to methicillin and other common antibiotics to health care workers’ knowledge gaps on MRSA, noncompliance with infection control guidelines, high endemicity from onset, uncontrolled use of antibiotics, and public unawareness.¹² It was also reported that various dental prescriptions were being used by general dentists due to clinical pressures and public health concerns. This contributes to antibiotic misuse, leading to resistance amongst various strains.¹³ Effective prevention measures require knowledge of and compliance with infection prevention and control guidelines by health care workers.

Our aim was to study the types and subtypes of MRSA isolated from oral swabs taken from dental personnel and to assess their knowledge and practices regarding MRSA infection prevention.

Materials and methods

An ethical clearance was granted from the Research Ethics Committee of Ajman University, UAE, and School of Dental Sciences, Krishna Institute of Medical Sciences, Deemed to Be University, Karad, India, for the conduct of the study.

Questionnaire

The questionnaire used in the current study is adapted from the framework of Sie et al.⁹ Prior to administration of the survey to the participants, it was piloted to 20 dental health care workers (DHCWs) and edited based on the results of the pilot surveys. Some redundant questions were removed, and some pertinent ones were restructured.

Before the collection of the samples and administering the questionnaire, each participant was informed about the study objectives, collecting procedure, and all the details regarding MRSA, after which an informed consent was signed, and the questionnaires were completed. The survey was administered through SurveyMonkey. The link to the questionnaire was circulated to the participants who provided informed consent.

The survey consists of 37 questions, including the demographic background of the DHCWs and assessment of the DHCWs’ knowledge of MRSA transmission and prevention, which included general knowledge of MRSA, MRSA guidelines, hand hygiene practices, and attitudes toward and confidence in their knowledge of the guidelines.

Collection of the samples

The samples were collected by a single examiner to standardise the sample collection techniques. Nasal swabs from participants were taken using sterile cotton swab sticks rotated over the nasal vestibule and transported in 0.9% sterile salt solution in cold conditions to the Microbiology Department. The samples were transferred immediately to the laboratory in an ice container.

Microbiological analysis

Bacterial identification

Each sample was processed with Vitek 2 system for bacterial identification. Out of 96 samples, 15 samples were identified as S. aureus. The stock of S. aureus was done on nutrient agar for further analysis.

Antibiotic susceptibility testing

Antibiotic susceptibility testing was performed by standard Kirby-Bauer disc diffusion techniques¹⁴ against routine antibiotics. Muller Hinton agar medium was used for antibiotic sensitivity testing. ATCC Staphylococcus aureus 25923 was used as a control.

The inoculums of the test strain to a density visually equivalent 0.5 McFarland turbidity standards was prepared by growing the strain in peptone water. The entire surface of plate of medium was inoculated using sterile cotton swab soaked in the inoculums. The excess was removed by squeezing the swab against the wall of the test tube just above the liquid level. The streaking was repeated 3 times by rotating the plate by 60 degree each time to ensure uniform distribution of inoculums. The surface of the medium was allowed to dry for 3 to 5 minutes but not longer than 15 minutes to allow for absorption of excess moisture. The discs of antibiotics to be tested were placed on the plate by using sterile forceps. The plates were incubated at 37 °C for 24 hours. The diameter of the clear zone around the disc was measured with a measuring scale, and the results were interpreted as susceptible, moderately susceptible, or resistant as per recommendations.

Kirby-Bauer technique for detection of MRSA

Methicillin resistance was tested by using 30 µg Cefoxitin discs by Kirby-Bauer disc diffusion method. MRSA strain isolated was inoculated in the tryptose phosphate broth for 2 hours. When broth showed turbidity, this turbidity was compared to 0.5 McFarland turbidity standard. Muller Hinton agar supplemented with 6% NaCl was used for culture. The plates were incubated at 37 °C for 48 hours and methicillin sensitivity pattern was recorded. The diameter of zone of inhibition was measured and interpreted according to National Committee for Clinical Laboratory Standard Guidelines (CLS) document M100-S31.2021. Following this method, one plate of the 15 plates showed MRSA with diameter of zone of inhibition 18 mm. The rest of the plates had a zone of inhibition greater than 20 mm.

Molecular analysis

The samples were cultured on blood agar plates and incubated at 37 °C for 2 days. Colonies with staphylococcal characteristics were inoculated in 10 mL LB growth medium in culture flasks and incubated at 37 °C and 120 rpm in a shaker incubator overnight. DNA extraction was carried out as per manufacturer's instruction for HiPurA Bacterial Genomic DNA purification kit (Himedia, Catalogue no: MB505).

Then, 2 mL culture was transferred to microcentrifuge tubes and centrifuged at 5000 rpm for 2 minutes. The supernatant was discarded, and cell pellet was resuspended in 200 µl solution of 45 mg/mL lysozyme solution and incubated at 37 °C for 30 minutes. 20 µL of Proteinase K solution (20 mg/mL) and 20 µL of RNase A solution (20 mg/mL) was added and incubated at room temperature for 5 minutes. 200 µL lysis solution was added and incubated at 55 °C for 10 minutes. The solution was prepared for binding onto column by adding and mixing 200 µL of ethanol and loaded onto column.

The column was centrifuged at 10,000 rpm for 1 minute and the flow through was discarded. Then, 500 µL of prewash solution was added and centrifuged at 10,000 rpm for 1 minute, and 500 µL of wash solution was added and tubes were centrifuged at 12,000 rpm for 3 minutes. To ensure complete ethanol removal, the tubes were given a dry spin at 12,000 rpm for 1 minute. Bacterial DNA was eluted with 100 µL elution buffer. The eluted DNA samples were checked using agarose gel electrophoresis and stored at −20 °C until required (Figure 1).

Fig. 1.

Representative gel image for polymerase chain reaction (PCR) performed for gene mecA. Lane 1: 100 bp ladder, lane 2: positive control, lanes 3, 4: methicillin-resistant Staphylococcus aureus (MRSA) samples showing presence of mecA gene.

Polymerase chain reaction (PCR) analysis

The samples were analysed using PCR for identifying MRSA using previously published literature. The MRSA samples were further genotyped for presence or absence of SCC mecI, SCC mecII, SCC mecIII, SCC mecIV a, SCC mecIV b, SCC mecIV c, SCC mecIV d, and SCC mecV [1]. PCR reagents from Genei, Bangalore, were used. The constituents of the PCR reaction mixture are detailed in the supplementary material.

The PCR conditions used for amplification of each of these genes were as stated below (Table 1). All the materials used in the study were supplied by HiMedia Laboratories Private Limited, India.

Table 1.

Total number of positive samples according to genotype.

Genotype	SCC mecI	SCCm ecII	SCCm ecIII	SCCme cIVA	SCCme cIVB	SCCme cIVC	SCCme cIVD	SCCmecIV (total)	SCCm ecV
No. of Positive samples	1	7	12	13	1	0	0	14	17
% of MRSA	3.2	22.6	38.7	41.9	3.2	0.0	0.0	45.2	54.8

MRSA, methicillin-resistant Staphylococcus aureus.

Results

After PCR, the samples were analysed using agarose gel electrophoresis; 2% agarose gels were used, and images were captured under UV using a Biorad ChemiDoc gel documentation system. A representative gel image of the mecA gene is represented in Figure 1. (Additional images in Figures 1 through 6 are in the supplementary material).

PCR analysis

Out of 100 nasal swabs examined, 73 samples showed growth on blood agar plates. After growing isolated colonies in overnight cultures and extracting DNA, it was found that DNA from all 73 samples was acceptable (Figure 2). Whilst screening for the presence of MRSA amongst these 73 samples, mecA primers were used and 31% of the swabs were identified as MRSA. For further genotyping of these MRSA samples, the PCR conditions were used as mentioned in the supplementary material (Supplemental Table 2). The results indicated that the MRSA type SCCmec type V (54.8%) was predominant, and SCCmec IV (45.2%) and SCCmec III (41.9%) were the most common subtypes found in the study group (Supplemental Table 2).

Fig. 2.

Genomic DNA samples extracted from overnight cultures.

Knowledge of DHCWs of MRSA infection

One hundred study participants responded to the interview (response rate, 66.7%); 37% of the participants were male and 63% were female. The majority were undergraduate students (66%) and younger than 25 years (77%). The majority of the participants (69%) had not heard of MRSA infection and had inadequate knowledge of MRSA infection; however, 81% of the respondents believed that MRSA is a bacteria. Only 29% of the participants think that a healthy person may have MRSA without feeling ill. Further, 85% of the participants reported that they have written polices and guidelines to control MRSA infection; 81% indicated that they were less confident in their knowledge on MRSA infection control protocols, and 94% mentioned that the dental clinics have written guidelines for hand hygiene. In addition, 98% reported that they always remember to clean their hands before they come into direct contact with their patients. Seventy-six percent were not aware of how MRSA colonisation can be treated; however, they were concerned when informed that they may become infected with MRSA (Table 2).

Table 2.

Response to the questionnaire on the knowledge of and practices to MRSA and its infections in dental practice.

Sr No	Question	Parameters	Percentage of participants answering
1.	Sex	Male	37
		Female	63
2.	Age group	16–25	77
		26–44	15
		45–64	08
		65+	00
3.	Position	Dental faculty/staff	05
		Dentist	10
		Dental nurse	10
		Dental technician	09
		Dental students	66
4.	How long have you been working at your present job	≤5 years	71
		6 to 10 years	20
		>10 years	09
5.	Have you heard of MRSA (methicillin-resistant Staphylococcus aureus)?	No	69
		Yes	31
6.	Is MRSA a virus or a bacteria?	Virus	13
		Bacteria	81
		Not sure	06
7.	Where have you heard about MRSA?	Books	19
		Internet	05
		Friends	07
8.	Can a healthy person have MRSA without feeling ill?	Yes	29
		No	02
		Not sure	69
9.	Have you obtained any information/education/training about MRSA from your workplace?	Yes	18
		No	82
		Not sure	00
10.	Does the institution(s) have written policies/guidelines to control MRSA?	Yes	00
		No	85
		Not sure	15
11.	Have you read through the guidelines?	Yes	00
		No	100
		Not sure	00
12.	How confident are you in your knowledge on MRSA infection control protocols?	1 (least confident)	81
		2	03
		3	05
		4	11
		5	00
		6 (very confident)	00
13.	What precautionary measures are taken when an MRSA infection is detected unexpectedly?	All personnel at the department are screened	09
		Only personnel who have had physical contact with patient or patient's environment without protection (glove/face mask/protective coats) are screened	18
		Only personnel who have had unprotected physical contact or been to patient's room for more than 30 minutes without face mask are screened	23
		Don't know	47
		Not relevant for me	03
14.	Do the dental clinics have written guideline for hand hygiene?	Yes	94
		No	03
		Don't know	03
15.	How confident are you on your knowledge on when and how to clean your hands?	1 (least confident)	00
		2	00
		3	00
		4	00
		5	07
		6 (very confident)	93
16.	Before contact with patient, do you remember to clean your hands before contact with patient?	a (always)	95
		b (at least 75% of the time)	3
		c (about 50% of the time)	2
		d (about 25% of the time)	00
		e (seldom/never)	00
		f (not relevant)	00
17.	After contact with patient, do you remember to clean your hands after contact with patient?	a (always)	98
		b (at least 75% of the time)	02
		c (about 50% of the time)	00
		d (about 25% of the time)	00
		e (seldom/never)	00
		f (not relevant)	00
18.	How often do you perform your hand hygiene on an average working day?	a (<10 times)	56
		b (10–19 times)	44
		c (20–29 times)	00
		d (30–39 times)	00
		e (40 –49 times)	00
		f (>50 times)	00
19.	Do you have finger rings on when working with patients?	a (never)	98
		b (sometimes)	02
		c (often)	00
		d (regularly)	00
		e (always)	00
		f (not relevant)	00
20.	Do you use bracelets or a wristwatch when working with patients?	a (never)	99
		b (sometimes)	01
		c (often)	00
		d (regularly)	00
		e (always)	00
		f (not relevant)	00
21.	If you were told that you are carrier of MRSA, how worried would you be that you might get MRSA?	1 (not at all worried)	03
		2 (a little worried)	67
		3 (quite worried)	26
		4 (very worried)	04
22.	Consider this scenario and then answer the question. “Mr X is senior dentist working in multispecialty dental clinics. He has just been told he has MRSA colonisation on the nostril; what might have caused this? Please tick all the reasons why this might have happened.	The clinic isn't clean and clinic staff haven't been washing their hands between patients	23
		Clinic staff haven't been washing their hands between patients AND Mr X had a visitor who had MRSA and passed it to him	77
		Mr X had an allergic reaction to the medication he was given	00
23.	How will MRSA colonisation be treated?	No treatment necessary	00
		It can be treated with special antibiotic ointment	18

MRSA, methicillin-resistant Staphylococcus aureus.

Discussion

MRSA^15,16 is a term used to describe S. aureus strains with acquired resistance to beta-lactam antibiotics, such as methicillin, oxacillin, and cephalosporins.^1,15,17 These bacteria develop beta-lactam antibiotic resistance by acquiring the gene mecA.

The results of this study indicate that about 30% of dental professionals harbour MRSA strains hence, they should be presumed potential MRSA reservoirs. It may be more common than previously believed for S. aureus or MRSA to colonise within the oral cavity without causing symptoms.^18,19 In one study, 1017 S. aureus isolates from more than 5000 oral samples had a 6% prevalence of MRSA.²⁰ S. aureus was linked to infections of periodontal implants in a study conducted in Sweden.²¹ A study amongst dental schools in Europe reported only a 1.5% prevalence of MRSA amongst dental students,²² whilst in Ukraine it was reported to be 17%.²³ Recent systematic reviews have reported the prevalence in India and Gulf Cooperation Council (GCC) countries to be 21% to 55%²⁴ and 35% to 45% in the GCC countries.²⁵ Although the significance of contaminated surfaces in MRSA transmission is debatable, health care professionals may spread MRSA strains via their gloves or uniforms.¹¹

To assess participants’ level of knowledge regarding pertinent MRSA prevention, this study used a knowledge-based questionnaire. Health authorities must dedicate more resources and time to educating health professionals on MRSA prevention as the study identified a wide range of factors linked to low knowledge levels.

Numerous studies have been conducted to determine how aware health care workers are of MRSA and follow regional MRSA prevention and control guidelines.^10,26, 27, 28 Even though some studies have revealed a reasonable level of knowledge, a considerable percentage of these have confirmed poor knowledge and low compliance, possibly as a result of a lack of a rigidly enforced national MRSA infection control guideline, which may be attributed to the 4- to 6-fold increase in MRSA cases in the society.^29,30

In the health care setting, the hands of health care workers are the most typical medium of transmitting pathogens associated with health care from patient to patient and from various objects to patients.^9,29,30 Hand hygiene has been emphasised as a crucial infection control strategy in publications from the World Health Organization that address how to stop the spread of pathogens in medical settings.^31,32 Literature shows that washing of hands or hand hygiene protocols are followed only 50% of the time by health care professionals.^32,33

One unexpected finding was the number of dentists and nurses who said they were unsure of what to do when an unanticipated MRSA case was found in a hospital. Given that they care for a substantial part of the community, dentists and nurses are expected to be role models in the health care community. In a related study involving health care workers in the United Kingdom, Brady et al²⁸ discovered a very low knowledge level amongst DHCPs. In agreement with Sie et al,⁹ both results show a very large gap between knowledge and adherence, even though the majority of respondents stated they were unaware of the MRSA guidelines. In a comparative study, Mediå³⁴ revealed that patient care providers were more likely to follow hand hygiene guidelines.

A few studies have examined molecular characteristics of Community-associated MRSA (CA-MRSA) in the UAE^35,36 and Middle East,^37,38 but no regional study has described the prevalence and epidemiology of MRSA amongst dental DHCWs in UAE.

To quickly implement contact precautions, it is essential to administer the admissions questionnaire to identify DHCWs likely to be colonised with MRSA. Asymptomatic colonisation typically precedes MRSA infection. Prescreening every patient is typically not cost-effective, especially in countries with low endemicity. Patients with risk factors such as those with surgical wounds, eczema, clinical infections of the skin and respiratory tract, diarrhoea, or MRSA positivity in the past; patients entering high-risk specialties; and patients and health care workers who have visited foreign medical facilities should be properly screened.

Regular adherence to validated protocols and given standards is the best way to prevent the contamination of MRSA on the environmental surfaces within the dental clinic.^39,40 National infection control guidelines outline hygiene precautions meant to shield people from the spread of blood- and airborne pathogens.41, 42, 43 The use of personal protective equipment (eg, gloves, masks, gowns, eye protection) and handwashing before and after contact with each patient are standard precautions to prevent nosocomial transmission of MRSA in the dental clinic.41, 42, 43 Considering that antibiotic resistance is a major threat, justifying the need for antibiotic prescriptions and considering the risk of uncontrolled usage amongst the patients need to be emphasised. DHCWs should be educated and made aware of the minimal outcomes to be achieved in dental antibiotic stewardship with national-level guidelines being set out.^43,44

Conclusions

The results indicated that the MRSA type SCCmec V type (54.8%) was predominant, and SCCmec IV (45.2%) and SCCmec III (41.9%) were the most common subtypes found in the study group. DHCWs can be reservoirs for MRSA, potentially leading to nosocomial infection or colonisation. Awareness of and fastidious attention to guidelines for infection control can reduce MRSA contamination in dental clinics, thereby decreasing nosocomial transmission. The standard infection control guidelines to decrease MRSA, such as hand hygiene, use of personal protective equipment, respiratory hygiene, sterile instruments and devices, and clean and disinfected environmental surfaces should be enforced. The knowledge of pertinent aspects of MRSA prevention was evaluated in this study using a knowledge-based questionnaire. Health authorities must dedicate more resources and time to educating health care workers on MRSA prevention as the study identified a wide range of factors linked to low knowledge levels. The authorities ought to take into account including MRSA studies in the curriculum of every dental school.

Author contributions

MAJ and AML conceived the ideas; WK and GSK collected the data; WK and GSK analysed the data; and MAJ and AML led the writing.

Conflict of interest

None disclosed.