In vitro antibacterial screening of some commercially available

Sodium fusidate ointment

 

Mohammed M. Safhi

Department of Pharmacology, College of Pharmacy, Jazan University, Jazan, Kingdom of Saudi Arabia

*Corresponding Author E-mail: msafhi@yahoo.com

 

Sodium fusidate ointment (SFO) has been widely used as antibacterial agent to treat a number of bacterial skin infections especially caused by Staphylococcus aureus. This study is mainly focusing on the efficacy of three different commercial brands of SFO 2% w/w available in the Kingdom. The brands were designated as brand A, brand B and brand C. The antibacterial spectrum of three different brands of SFO was determined against Staphylococcus aureus and Streptococcus pyogenes. The antibacterial sensitivity test is performed by agar well diffusion technique. The comparative study showed no significant difference between brands screened against the tested organisms. However, all the brands showed predominant activity against Staphylococcus aureus when compared to Streptococcus pyogenes.

 

 

1. INTRODUCTION:

Superficial bacterial skin infections are common in clinical practice may lead to either as primary infection or as secondary infections to some other cutaneous disease  caused by many bacteria especially Staphylococcus aureus and Streptococcus pyogenes leading to impetigo, boils, infected eczema and wounds etc. Primary skin infections caused by Gram-negative bacteria are not common but may occur if the patient is immunocomprosied or diabetic¹. Earlier studies reported that fusidic acid in the form of either cream or ointment has shown fast and effective healing in superficial skin and soft tissue infections². Fusidic acid has a narrow antibacterial spectrum isolated from the fungus Fusidium coccineum³, mainly against Gram-positive bacteria; in particular against S. aureus, and has been shown to be active against both Methicillin-sensitive Staphylococcus aureus (MSSA) and Methicillin-resistant Staphylococcus aureus (MRSA)^4,5. The molecule exhibits steroid like structure, but does not possess any steroid activity⁶. Sodium fusidate is the sodium salt of fusidic acid, a bacteriostatic antibiotic able to penetrate intact skin has been used to treat infection caused by Staphylococcus aureus and Streptococcus pyogenes.  The enhanced way of treating superficial skin infections is through the use of topical antimicrobials.

 

Topical treatment delivers a high concentration of a drug to the desired area and has no systemic effects. However, Fusidic acid resistance has been reported throughout the world especially against Staphylococcus aureus^7,8. This study is mainly focusing on the efficacy of various branded products of sodium fusidate 2% w/w available in the Kingdom.

 

2. MATERIALS AND METHODS:

2.1. Collection of Materials

Commercially available sodium fusidate 2% w/w ointments of three different brands were purchased, designated as brand A, brand B, brand C and their manufacturer’s details were noted. All Chemicals used for this study was analytical grade.

 

2.2. Strains used

24 h culture of Staphylococcus aureus and Strptococcus pyogenes were used in this study.

 

2.3. Properties of Sodium fusidate ointment and antibacterial screening

The colour, texture, homogeneity and pH were evaluated on preliminary basis.  The laboratory culture of S.aureus and S.pyogenes were sub cultured and the concentration of working stock culture was assessed as 10^-6 CFU/ml. The agar well diffusion technique was followed for antibacterial susceptibility test.

 

 

Table 1:    Properties and manufacturer’s details about the ointment

Brands	Properties of the ointment				Manufacturer’s details
	Colour	Texture	Homogeneity	pH	Batch number	Mfg	Exp.
Brand A	White	Smooth	Yes	6.8	EF 3105	07, 2011	07, 2014
Brand B	White	Smooth	Yes	6.9	MK 070	09, 2011	09, 2013
Brand C	White	Smooth	Yes	6.8	51775	05, 2011	05, 2014

 

 

 

Specified quantity of Muller Hinton (MH) agar was prepared and plated in aseptic condition. 0.1 ml of standardized culture was poured on the MH agar plate and spread with L shaped glass spreader. By using sterile cork borers wells were made. The ointments were dissolved in xylene to get the known concentrations of 10 µg/0.1ml and poured in to the respective wells. After 24 h of incubation at 37⁰ C the zone of inhibition was measured and tabulated.

 

2.4. Statistical analysis

All the experiments were performed six times (n = 6), the data were subjected to one way analysis of variance (ANOVA), the level of significance is P<0.05 using Graph pad Instat software, USA. The efficacy was compared by performing Tukey comparison test and Bartlett's test (post test).

 

Table 2:    Anti bacterial effect of sodium fusidate ointment against tested organisms

Formulation	Zone of inhibition (mm)
	S. aureus	S. Pyogenes
Brand A	28.16 ± 2.2	20.6 ± 3.4
Brand B	27.3 ± 0.8	19.5 ± 2.5
Brand C	26.5 ±  1.6	19 ± 2.8

* Each value is the mean of six batches with standard deviation

 

 

 

Table 3: Comparative study on the efficacy of various brands against tested organism

Comparison	Organisms
	S. aureus	S. pyogenes
Brand A vs Brand B	P>0.05, ns	P>0.05, ns
Brand A vs Brand C	P>0.05, ns	P>0.05, ns
Brand B vs Brand C	P>0.05, ns	P>0.05, ns

ns – Non significant, Post hoc- Tukey comparison test and Bartlett's test suggests that the differences among the SDs is not significant among treated groups.

 

Figure 1. Anti bacterial effect of sodium fusidate ointment of three different brands against selected organisms

 

 

3. RESULTS AND DISCUSSION:

Generally, ointment bases used in formulation could cause reduction in antimicrobial efficacy of the incorporated medicaments and may lead to drug resistance.  Rennie (2006)⁹ demonstrated the susceptibility tests of fusidic acid against a sampling of Canadian hospital-based isolates and reported that S.aureus and MRSA strains were resistance to fusidic acid. The decision to use topical fusidic acid must therefore be tempered by the potential to develop resistance. Denis Spelman, 1999 ¹⁰ demonstrated that topical fusidic acid is of similar efficacy to other topical antimicrobials. Hence it is essential to estimate the efficacy of commercially available sodium fusidate ointment in vitro. A total of three different brands of sodium fusidate ointment 2% w/w marketed in Saudi Arabia were screened. The parameters of ointments such as colour, texture, homogeneity, pH were satisfactory and acceptable for ointment (Table 1). The pH of ointments range was 6.8 to 6.9 and complies within the pH ranges of skin as 6.0 to 7.2 good for topical use. The visual inspection done for homogeneity of ointments reveals that all the three brands were homogeneous, free from lumps and foreign particles. The in vitro study was calculated in terms of zone of inhibition in mm. The results of antibacterial screening was summarized in Table 2 demonstrating that the brands A, B and C showed 28.16 ± 2.2 and 20.6 ± 3.4; 27.3 ± 0.8 and 19.5 ± 2.5; 26.5 ± 1.6 and 19 ± 2.8 mm against Staphylococcus aureus and Streptococcus pyogenes respectively. In this study xylene was used as solvent to dissolve ointment to get the known concentrations of 10 µg/0.1ml. Therefore, solvent control study was also performed. The results suggested that the solvent xylene was not showing any anti bacterial activity against the tested organisms.

 

Nimbekar et al. (2012)¹¹ was established with four different formulations of framycetin sulphate ointment and their antibacterial studies were well compared with marketed framycetin sulphate ointment. Their studies showed that formulation 1(F1) exhibit better effect against bacillus subtilis when compared to the rest. The comparative study on the efficacy of three different commercially available brands against tested organism is tabulated in table 3. The studies showed that no significant difference between brands screened against the tested organisms. Bartlett's test suggests that the differences among the SDs are not significant among treated groups. All the brands showed predominant activity against Staphylococcus aureus when compared to Streptococcus pyogenes (Fig 1).

 

4. CONCLUSION:

The present study provides useful information on the comparative efficacy of three brands of sodium fusidate ointment 2% w/w. Results suggested that all the branded ointment exhibit good effect against the tested bacteria in vitro.  However, in vivo studies are under process in order to know about efficacy of the ointments. 

 

 

5. REFERENCES:

1.       Long BH. Fusidic acid in skin and soft-tissue infections. Acta Derm Venereol S 216 ; 2008:14–20.

2.       Jasuja K, Gupta S, Arora D, Gupta V. Bacteriology of primary pyodermas and comparative efficacy of topical application of mupirocin and sodium fusidate ointments in their treatment. Indian J Dermatol Venereol Leprol. 67; 2001: 132–134.

3.       Collignon P and Turnidge J. Fusidic acid in vitro activity. Int J Antimicrob Agents. 12 (S 2); 1999: S45– S58.

4.       Verbist L. The antimicrobial activity of fusidic acid. J Antimicrob Chemother. 25; 1990: 1–5.

5.       Bishop EJ and Howden BP. Treatment of Staphylococcus aureus infections: new issues, emerging therapies and future directions. Expert Opin Emerg Drugs. 12; 2007: 1–22.

6.       Wilkinson JD. Fusidic acid in dermatology. Br J Dermatol. 139 (S53); 1998: 37–40.

7.       Elston DM. Topical antibiotics in dermatology: emerging patterns of resistance. Dermatol Clin. 27; 2009: 25–31.

8.       Dobie D and Gray J. Fusidic acid resistance in Staphylococcus aureus. Arch Dis Child. 89(1); 2004: 74-77.

9.       Rennie, R.P., 2006. Susceptibility of Staphylococcus aureus to fusidic acid: Canadian data. J Cutan Med Surg., 10: 277–280.

10.     Denis Spelman. Fusidic acid in skin and soft tissue infections. International Journal of Antimicrobial Agents 12; 1999: S59–S66.

11.     Nimbekar TP, Bhange PG, Wanjari BE, Mehere AP. Formulation and Evaluation of some framycetin sulphate ointment. IJPBS. 3(2); 2012: 327 – 332.

 

 

 

Received on 13.02.2013       Modified on 03.03.2013

Accepted on 10.03.2013      © RJPT All right reserved