Inhibitory effects of different hand sanitizers against the resident microflora of skin

INTRODUCTION

Most of the germs that cause serious infections in healthcare are spread by people’s actions. Hand hygiene is a great way to reduce the transmission of infectious disease particularly in hospital.^1,2 There are several methods of hand hygiene such as hand washing or sanitizer to kill or eliminate the pathogenic microorganisms present on hands. However, various organizations such as Centers for Disease Control and Prevention (CDC) and WHO have been published guidelines on appropriate hand hygiene.² Currently, the concept of hand sanitization has been in place right from the start of the hand hygiene campaign by many governmental and non-governmental organization.^3,4 Previous researchers have been focused on the importance of hand sanitizer as an infection control means particularly against the communicable diseases.^2,4

However, in the early 2000s the CDC has been issued a proper guideline which recommended that alcohol-based hand rub (ABHR) should be routinely used for decontaminating hands.⁵ In recent years, the most commonly used hand sanitizers are ABHR which are often composed of alcohol, ethanol, isopropanol or propanol.^1,6 The recommended concentration range of these sanitizers are 60 to 95%.⁷ For the time being, hand sanitizers not only very effective to minimize the infection rates but also these are very useful alternative source of water where access to water is so limited for hand cleaning.^6,7 Beside the antibacterial activity, alcohol-based hand sanitizers have been reported as one of the commonly recommended hand hygiene against the diseases outbreaks causes by Ebola-Virus.^8,9 As described by previous researchers that hand sanitizers have been found as very effective agent in order to eradicate the gastrointestinal infection as well as hospital acquired infection.^7,10 Eventually, people are now more interested to use hand sanitizer instead of only hand washing due to its better performance against the resident skin flora such as Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis.⁶ As a result, many companies have now launched verities of hand sanitizer in the market without verifying the proper concentration and activity of the products which making huge dissatisfaction among the customers.^11,12 To confirm the efficacy of the hand sanitizer, present study attempted to isolate several inherent microflora from the hand of laboratory stuffs and introduce the effectivity of the three common hand sanitizers (Dettol, Savlon and Purell) against the growth of the microbes.

METHODS

Type of study, sample collection and processing

This is an observational or analytical study where the samples (3 types of hand sanitizer such as Dettol, Purell and Savlon) were randomly collected from different super shop in Dhaka city, Bangladesh, from June 2018 to September 2018 to detect their efficacy against some skin residual micro-flora. All the samples were transported in the microbiology laboratory for the detection of anti-bacterial activity.¹³

Test isolates

Four important bacteria such as Staphylococcus spp., E. coli, Klebsiella spp., and Pseudomonas spp. were isolated from the surface of the hand of 5 laboratory stuff (laboratory cleaner 1, laboratory cleaner 2, lab assistant 1, lab assistant 2 and research assistant) who worked at microbiological laboratory, Stamford University Bangladesh. The sterile cotton swabs were rubbed on the surface area of the hand and lawn on to the MacConkey agar, mannitol salt agar and cetrimide agar then the plates were incubated at 37 ºC for 24 hours.¹⁴

Antibacterial activity of the products through agar well diffusion methods

For the determination of anti-microbial activity, modified agar well diffusion method was employed using MHA plates.^15-17 Suspensions of different bacterial strains such as E. coli, Pseudomonas spp., Klebsiella spp., Staphylococcus aureus were prepared using normal saline, consisting of 10⁶ cfu/ml with a turbidity equivalent to that of the 0.5 ml McFarland standard. Each suspension was then inoculated on the Muller-Hinton agar (MHA) (Oxoid Ltd., Basingstoke, Hampshire, England) by using Lawn method. 4 wells were created on the plates using a 6 mm cork borer and 0.1 ml of different concentrations (100%, 50% and 25%) of the test substance (Dettol, Purell and Savlon) was added to individual wells. After 24-hour incubation at 37 °C, the zones of inhibition were then measured.

Minimum inhibitory concentration

The MIC of the substances was estimated to identify the least concentration, which had the ability to inhibit the growth of test bacteria.^18,19 Different concentrations (such as 2 µl, 4 µl, 8 µl, 16 µl, 32 µl, 64 µl, 128 µl, 256 µl, 512 µl, 1024 µl and 2048 µl) of the substances (Dettol, Purell and Savlon) were introduced into the inoculum broth.

Minimum bacteriocidal concentration

To determine the minimum bacteriocidal concentration (MBC) of the test ingredients, the same concentrations of the substances (as indicated in MIC) were usedagainst the same bacterial suspension and evaluated the lowest amount, which can kill the growth of bacteria.⁸

RESULTS

Detection of different bacteria from the hands of laboratory stuffs

Staphylococcus spp., Klebsiellaspp., E. coli and Pseudomonas spp. were found from the all 5 laboratory stuffs (laboratory cleaner 1, laboratory cleaner 2, lab assistant 1, lab assistant 2 and research assistant). Among the 5 stuffs the massive microbial growth was found on the samples collected from the laboratory cleaners 1 and 2. The bacterial contamination was in moderate range in the hands of laboratory assistant 1 and 2 but the bacterial contamination was quantified in minimum range in case of research assistant (Table 1).

Antibacterial activity of different hand sanitizers through agar well diffusion methods

All three hand-sanitizer exhibited their anti-bacterial activity against the tested isolates (Table 2). The maximum zones of inhibition were recorded at concentrations of 100% for all the samples. In case of Dettol sample, the zone of inhibition was quantified as 40, 45, 55 and 35 mm against Staphylococcus spp., E. coli, Klebsiella spp., and Pseudomonas spp. consecutively at 100% concentration, at 50% concentration of dettol the zone of inhibition 26, 25, 45 and 25 mm was measured against Staphylococcus spp., E. coli, Klebsiella spp., and Pseudomonas spp. consecutively and 25% of Dettol showed anti-bacterial activity 10, 8, 20 and 15 mm against Staphylococcus spp., E. coli, Klebsiella spp., and Pseudomonas spp. consecutively (Table 2). The zone diameter (30-50 mm) was recorded for Purell against the isolates at 100% concentration while the zone diameter 20-35 mm was measured at 50% concentration and the growth of bacteria was killed up to 15 mm at 25% of contractarian. Conversely, 100% Savlon exhibited the zone diameter 35, 45, 40 and 35 mm against the growth of Staphylococcus spp., E. coli, Klebsiella spp., and Pseudomonas spp. consecutively. 50% of the savlon was able to inhibit the growth of bacteria with zone diameter within the range of 20-38 mm likewise, 25% of savlon showed zone diameter 12, 17, 15 and 22 mm against the Staphylococcus spp., E. coli, Klebsiella spp., and Pseudomonas spp., consecutively (Table 2). 100% samples of all the disinfectant were found to be more effective to reduce the growth of all the tested bacteria. Among the 3 disinfectant savlon was generated maximum zone diameter at lowest concentration (25%) (Table 2).

Determination of MIC and MBC of different hand sanitizers

Additionally, the result of MIC and MBC of the samples were supported the results of agar well diffusion methods (Table 3). In case of dettol sample, the MIC and MBC was recorded at 8 µl and 16 µl respectively against Staphylococcus spp., 32 µl and 64 µl concentrations were observed as MIC and MBC respectively for E. coli, 128 µl and 256 µl for Klebsiella spp. and 8 µl and 16 µl were documented as MIC and MBC for Pseudomonas spp. (Table 3). Another hand sanitizer purell showed MIC value at 128 µl and MBC at 256 µl against Staphylococcus spp., Klebseilla spp. and Pseudomonas spp. likewise the value MIC and MBC was recorded at 256 µl and 512 µl against E. coli respectively. Likewise, the 4 µl and 8 µl concentration of Savlon were determined as MIC and MBC respectively against Staphylococcus spp., Klebseilla spp. and Pseudomonas spp (Table 3).

In this study, the lowest concentration of savlon (4 µl and 8 µl) was recorded as most effective hand sanitizer against the bacteria found from the surface area of the laboratory.

+++: High growth rate; ++: Moderate growth rate; +: Low growth rate.

All the experiments were performed three times and one reproducible data

All the experiments have been performed three times and one reproducible data has given.

All the experiments have been performed three times and one reproducible data has given.

DISCUSSION

As reported in many studies that the upper layer of the skin serve huge amount of nutrient for the propagation of different bacteria especially Staphylococcus aureus, Staphylococcus epidermidis, Cornnebacterium, Streptococcus pyogenes etc., those are responsible for transmitting several communicable diseases as well as hospital acquired infection.^20-23 Beside such diseases outbreaks these bacteria can also be transmitted as contamination during the laboratory experiment.⁵ In order to eliminate the proliferation of such bacteria, use of hand sanitizer or disinfectant is very significant before starting any experiment and taking any food as well.^22,16-26

In recent years, the rate of communicable diseases and hospital acquired infection have increased alarmingly which has become a serious public health problem through worldwide.^27,28 The most common route for transmission of infection or communicable diseases are hands and skin. Thus hand hygiene has become essential to prevent communicable disease and diseases that acquired from health care centre including nosocomial infection.^29-30 Although, human skin contain two different types of normal flora, one that always presence on skin known as resident flora e.g., Staphylococcus aureus, Staphylococcus epidermidis, Enterococcus faecalis and other that are introduced on skin from external environment, which called transient flora consists S. aureus, Escherichia coli, and Pseudomonas aeruginosa.^2,4 Analysis of several scientific studies explained that hand washing without sanitizers, does not remove pathogenic microorganisms from hands. Even most of the pathogenic organisms about 80% remain on skin, therefore scientists have introduced different hand sanitizers to improve skin condition as well as to reduce" will be added after different and pathogenic microorganisms such as bacteria, virus, fungi from hand and skin surfaces and in improving skin condition.^6,22

Moreover, using hand sanitizers decreased the risk of spreading gastrointestinal and respiratory infection can minimize skin dryness and irritation also in reducing the rate of absentee in schools and college. Direct use of alcohol can cause skin dryness but alcohol based sanitizers are effective to prevent infection in hospitals and also in reducing the load of pathogenic microorganisms from hand.^31,32

CONCLUSION

Our study showed that the Dettol, Purell and Savlon have suitable range of antibacterial activity against the isolated bacteria from the hands of laboratory officers. So, as a final point it can be assumed that the hand sanitizers are more effective to eliminate the skin microflora than the hand washing and ordinary water. However, there are several complain in market by the customers regarding the low efficacy of the hand sanitizer. Therefore, the higher authorities and regulatory bodies should justify the client’s opinion very positively and ensure the quality of the products.

ACKNOWLEDGEMENTS

Authors would like to thank Microbiology Laboratory, Stamford University Bangladesh for laboratory facilities.

Funding: No funding sources

Conflict of interest: None declared

Ethical approval: Not required

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