Assessment of Antibacterial and Anti-biofilm Effects of Vitamin C Against Pseudomonas aeruginosa Clinical Isolates

Abstract

There is a persistent need to look for alternative therapeutic modalities to help control the pandemic of antimicrobial resistance. Assessment of antibacterial and anti-biofilm effects of vitamin C (ascorbic acid) was the aim of the current study. The micro-dilution method determined the minimal inhibitory concentration (MIC) of ascorbic acid or antibiotics alone and in combinations against Pseudomonas aeruginosa (P. aeruginosa) clinical isolates. The micro-titer plate method monitored the effect of ascorbic acid on the biofilm-producing isolates of P. aeruginosa. The effect of ascorbic acid on the differential expression of different antibiotic-resistant genes and biofilm encoding genes of P. aeruginosa isolates were also tested using real-time polymerase chain reaction (PCR). For in vivo assessment of the antibacterial effects of ascorbic acid alone or combined with an antibiotic, rats were infected with P. aeruginosa clinical isolate followed by different treatment regimens. MICs of ascorbic acid among P. aeruginosa isolates were in the range of 156.2–1,250 μg/ml, while MIC50 and MIC90 were 312.5 and 625 μg/ml, respectively. At sub-inhibitory concentrations (19.5–312.5 μg/ml), ascorbic acid had 100% biofilm inhibitory effect. Furthermore, ascorbic acid-treated bacteria showed downregulation of genes underpinning biofilm formation and antibiotic resistance. In vivo assessment of vitamin C and ceftazidime in rats showed that administration of both at a lower dose for treatment of pseudomonas infection in rats had a synergistic and more powerful effect. Vitamin C shows excellent in vitro results as an antibacterial and anti-biofilm agent. Vitamin C should be routinely prescribed with antibiotics to treat bacterial infections in the clinical setting.

Gentamicin–Ascorbic Acid Encapsulated in Chitosan Nanoparticles Improved In Vitro Antimicrobial Activity and Minimized Cytotoxicity

“…Finally, AA may downregulate antibiotic-resistant genes. Our results were supported by the previous studies [ 45 , 46 ]…”

Ascorbic Acid from <i>Citrus limon</i> (L.) Osbeck Fruit Source: A Promising Natural Agent for Caries Prevention and Management

“…These MIC and MBC result variations may be due to the susceptibility pattern of the S. mutans strains used, the purity of ascorbic acid, and the experimental settings carried out in different laboratories. Ascorbic acid at a sub-inhibitory dose of 19.5-312.5 mg/ml demonstrated 100% anti-biofilm activity and also displayed downregulation of antibiotic resistance genes against Pseudomonas aeruginosa 35 . It is reported that in clinical setting, antibiotic therapy should be prescribed along with ascorbic acid for routine bacterial infection treatment 35 .…”

“…Ascorbic acid at a sub-inhibitory dose of 19.5-312.5 mg/ml demonstrated 100% anti-biofilm activity and also displayed downregulation of antibiotic resistance genes against Pseudomonas aeruginosa 35 . It is reported that in clinical setting, antibiotic therapy should be prescribed along with ascorbic acid for routine bacterial infection treatment 35 . In our study, ascorbic acid at a sub-MIC concentration (6.25 mg/ml) displayed no significant change in growth rate pattern and is in agreement with the results of Eydou et al, 34 reporting that there is no statistically significant difference in the growth rate pattern among the control and ascorbic acid treated at 1/2 sub-MIC (5.61 mg/ml) against S. mutans.…”

Correlation between Perturbation of Redox Homeostasis and Antibiofilm Capacity of Phytochemicals at Non-Lethal Concentrations

“…A concentration below the MIC (4 μg/mL) of ellagic acid reduced biofilm development of Streptococcus dysgalactiae NCTC 4671 up to 27% and S. dysgalactiae ATCC 27957 up to 21%, but 4 μg/mL had no effect on S. aureus biofilm growth [ 18 ]. In addition, even with the same phytocompound, it is not always possible to gather unique conclusions as different investigations were often carried out with variations in the methodologies, i.e., differences in sub-lethal doses, microbial targets, microbial cell density, and culture media [ 19 ]. Time could also be a key factor.…”

“…Upon 40 μg/mL quercetin treatment, Klebsiella pneumoniae , P. aeruginosa and Yersinia enterocolitica displayed a >90% increase in sensitivity to tetracycline, kanamycin, and gentamycin [ 24 ]. According to Abdelraheem et al [ 19 ], vitamin C (ascorbic acid) had a synergistic effect with antibiotics against P. aeruginosa both in vitro and in vivo. The authors suggested that vitamin C should be consistently prescribed with antibiotics to treat Pseudomonas infections to reduce treatment duration and antibiotic dose.…”