Prevalence and investigations of bacterial contamination in dental healthcare associated environment

1 Introduction

Dental staff and patients are exposed daily to increased risk of cross-infection in the dental clinics setting by a wide range of pathogens and spores transmitted by pollutants and particles resulting from dental operating procedures (Harrel and Molinari, 2004; Castiglia et al., 2008; Szymanska, 2007). The oral microbial flora provides a potentially important source of cross-infection and contamination in dental clinics around the world (Ghosh and Mallick, 2012). Microorganisms can spread during a dental procedure following the dispersion of aerosols and splashes, and pathogens can be transmitted via blood and saliva then can be transmitted to the surrounding surfaces found in the dental clinics (Castiglia et al., 2008). Among the significant bacteria that can occur infection in dental environments are Pseudomonas aeruginosa, Streptococcus pneumoniae, Klebsiella pneumoniae, Mycobacterium tuberculosis, Legionella, Escherichia coli and pneumophila. Also, infectious agents such as Hepatitis B and C virus, Human Immunodeficency virus, Epstein Barr virus, Herpes Simplex virus, and Cytomegalovirus (Castiglia et al., 2008; Pasquarella et al., 2010). Many of these bacterial infections can survive on surfaces for extended periods of time unless they are removed through sterilization or disinfection (Kohn et al., 2003).

According to some studies, the environment, such as water, air, and surfaces, can play an essential role in pathogen transmission. Biofilm formation, water stagnation and a lack of disinfection in dental unit water systems encourage the growth of microorganisms (Barbeau and Nadeau, 1997; Checchi et al., 1998; Singh and Coogan, 2005; Zanetti et al., 2000). Moreover, generators and air–water infusion pumps can sometimes nebulize the saliva and microorganisms contained in the patient's mouth, contaminating the surrounding air and surfaces (King, 1997). Disease causes when microorganisms pass through the body, settle in a suitable location, and start reproducing (Andersen et al., 2009). Some people are more concerned about aerobic bacteria because they have a history of rheumatic heart disease, endocarditis mitral, valve prolapse and prosthetic joints (Williams et al., 2003).

Such contaminants can cause direct dental infection and also provide an indirect source of work-related risks (Pasquarella et al., 2010). Microbial prevalence contributes in a number of ways to disease spread in the dental clinics setting from patient to the clinical staff (Merchant,1991), from dental staff to the patient, from one patient to another (Borer et al., 2005), as well as from the dental clinic itself to the public (Brady et al., 2006). Infections in dental clinics settings which involve antibiotic-resistant bacterial strains are particularly important from the perspective of public health (Perveen et al., 2013). For this reason, the control of pathogens is highly significant in reducing infection spread (Woo and Joo, 2010, Kazi and Rajeev, 2012). Gugelmin et al., 2003 reported the prevalence of microbial contamination in waterlines used in a dental unit and concluded that the resultant biofilm formation is likely to contaminate dental-unit water.

The aim of the present study was to determine the prevalence of bacteria on various surfaces (a dental chair-arm rest; a sink and faucet; the floor beneath a dental chair; a towel dispenser; handles to a light and instrument table; paper dental records; an X-ray viewer; a bench and head rest) located in five departments (pediatric dentistry, implant, dental prosthetics, oral medicine and restorative dentistry). Samples were taken before and after patient-treatment.

2 Materials and methods

3 Results

Table 1 shows the total number of bacterial colonies isolated before and after patient treatment in each specimen in each surface from the various departments. All surfaces located in all departments were contaminated with bacteria. Bacterial contamination ranged between 209 and 644 colony forming units. The Implant Department was the most contaminated, while the Department of Oral Medicine was the less contaminated than other departments. The most common isolated bacteria from the various surfaces sampled were species of Staphylococcus, Streptococcus, Pseudomonas, Bacillus and Micrococcus (Fig. 1).

Close

Fig. 1

Bacteria isolated from the various dental clinic surfaces.

Export to PPT

The results of the present study showed the high prevalence of bacteria on various surfaces located in five departments of a hospital dental clinic. Bacterial contamination was significant after the patient visited various departments for treatment. (Table 1). The results show that the highest bacterial count was found in the Implant Department, this could be due to variety of clinical practices which are performed in this Department compared to others. In contrast, samples from the Department of Oral Medicine showed the lowest number of bacterial isolates; due presumably to the limited number of clinical practices and types of treatments provided at these clinics.

4 Discussion

The results of current study showed that all surfaces of dental clinics before treatment and after treatment of patients were contaminated with bacterial species. A number of studies have reported widespread microbial community in the mouths of dental patients (Spolidorio and Duque, 2013), and doubtless the contamination of dental clinic surfaces occurs because of hand transfer of blood and saliva during patient treatment (Engelmann et al., 2010). In this study, the most common bacteria isolated were species of Staphylococcus, Bacillus, Streptococcus, Pseudomonas and Micrococcus. Staphylococcus aureus is considered to be the most isolated bacteria compared to other bacterial species. S. aureus or Methicillin-resistant Staphylococcus aureus (MRSA) colonization of the oral cavity may be more common than previously thought (Didilescu et al., 2005; Smith et al., 2001). One study of over 5000 oral samples found an MRSA presence of 6% between 1017 S. aureus bacteria isolated (Smith et al., 2003). One other Swedish study linked S. aureus to periodontal-implant infections (Renvert et al., 2008). MRSA colonization rates were compared before and after patients visited each clinic for treatment in study of Faden, (2019). The findings of revealed that the prevalence of MRSA significantly increased after patients visited the area. Also, research Hoshyari et al. (2019) agreed with the current study's findings that there was a notable difference in the frequency of pathogens before and after clinical practice, and Staphylococci were more prominent on the outer surface. Other members of these genera have frequently been shown to be the most commonly isolated bacteria from dental- clinical settings (Coelho et al,. 2016; Castiglia et al,. 2008; Pasquarella et al,. 2010, Witwit et al,. 2019). The presence of such variety of microorganism on theses clinical surfaces mandate the implementation of more powerful decontamination protocol in dental clinics to reduce the risk of cross infection.

Dental clinic is now a health risk for a variety of infections, particularly in immunocompromised individuals (Pankhurst and Coulter, 2007). As a result, several other researchers have emphasized the importance of personal safety systems as well as common disinfection practices in reducing the infection risk related to dental airborne particles (Schel et al., 2006). Domestic infection control standards delineate hygiene measures intended to protect individuals from blood-borne and airborne pathogen transmission Standard warnings for preventing bacterial nosocomial infection spread in the dental hospital (British Dental Association, 2003; Siegel et al., 2007) including hand decontamination before and after contact with each patient, as well as the use of personal safety devices such as mask, robe, gloves and protective glasses. (Baehni et al., 2005; Siegel et al., 2007).

5 Conclusion

Indoor microbial contamination control is especially important because various pathogenic bacteria can be transmitted from the surroundings to patient populations. The aim of the present study was to assess the prevalence of bacteria on ten surfaces in the dental clinics of King Saud University, Dental Hospital, both before and after treatment of selected patients. The results show that all tested surfaces were contaminated with bacteria, with the degree of contamination being considered relatively high for all clinics. The difference in the level of bacterial contamination is due to the type of practice in each setting, with the most frequently isolated bacteria being species of Bacillus, Staphylococcus, Streptococcus, Pseudomonas and Micrococcus. We conclude that the prevalence of these bacteria in dental clinics requires critical attention to the level of disinfection and hygiene used in all clinics.