Effect of Vitamin C on Penicillin G Efficacy to Inhibit Bacterial Populations

Abstract

Bacterial resistance to antibiotics may have evolved from either the natural resistance mechanism associated with bacterial
structure and/or related to various bacterial strategies, ranging from the enzymatic inactivation of the antibiotic, to drug
efflux and to the development of multidrug resistance clones. There is increasing interest in some vitamins, such as
Vitamin C, as potential agents for reducing bacterial persistence and, therefore, these may help in treating many infectious
diseases of bacterial origin.
This study was designed to determine the possible effect of Vitamin C in inactivating bacterial populations of
Staphylococcus aureus and Escherichia coli, alone and in combination with Penicillin G. Potential antibacterial effect
was evaluated using the Cup Cut Agar diffusion method. Inoculated with about 1x108 cfu.ml-1 from a 16 to 18 hr culture
of bacteria. A Vitamin C concentration, calculated to 10 mg, was added to a range of Penicillin G concentrations of 30,
60 and 120 mg. Plates were then incubated overnight at 37o
C. All experiments were performed in 5 replicates, where the
mean was used to extrapolate our data.
The results showed that Vitamin C displayed a similar antibacterial effect to that of Penicillin G (at 120 mg) on E. coli
populations where this effect was significantly (P < 0.05) enhanced with the three Penicillin G concentrations employed.
S. aureus responded to the effect of the combined Vitamin C and Penicillin G more than E. coli. Therefore, Vitamin C
potentiated the effect of the Penicillin G antibiotic to an extent that the combined sub-effective or sub-therapeutic dose of
Penicillin G (30 mg) with Vitamin C (10 mg) displayed a similar effect to that of 120 mg Penicillin G alone.
It may be elucidated that Vitamin C facilitates access of the treatment agent to its target, resolving some aspects of the
problem of bacterial resistance. This study provides evidence that Vitamin C displays a crucial role in inactivating
bacterial populations and has the ability to maximize the effect of some antibiotics deployed at a lower concentration that
might help in minimizing some undesirable side effects. Vitamin C, in addition to its role in maintaining human immunity
against the cold virus and its antioxidant role can, therefore, contribute to the treatment of bacterial infectious diseases that
are non-responsive to a variety of antibiotics.