Synergistic Antibacterial Activity of Pleurotus Species (Mushroom) and Psychotria microphylla (Herb) against Some Clinical Isolates

Aims: This study investigated the synergistic antimicrobial activity of the extracts of Pleurotus species and Psychotria microphylla against five clinical bacterial isolates: Escherichia coli, Pseudomonas aeruginosa, Salmonella Typhi, Klebsiella pneumoniae and Staphylococcus aureus from Federal Teaching Hospital, Abakaliki (FETHA), Ebonyi State, Nigeria.
Study Design: This was an experimental study.
Place and Duration of Study: This study was carried out in the Department of Applied Microbiology Laboratory, Ebonyi State University, Abakaliki, Nigeria between October, 2014 and December, 2014.
Methodology: Antimicrobial components from the mushroom and herb were extracted with water and ethanol. In this, the antimicrobial activities were examined by agar well diffusion method adapted from Kirby Bauer disk diffusion technique against confirmed isolates of Escherichia coli, Pseudomonas aeruginosa, Salmonella Typhi, Klebsiella pneumoniae and Staphylococcus aureus. Mixtures of the different extracts (mushroom and herb) at varying ratios (of 1:1, 1:2, 2:1) were also used to determine their synergistic inhibitory effects at 37ºC and 24 hours incubation. Inhibition zone diameters were measured and recorded.
Results: The result revealed antibacterial activity of the extracts although at varying degrees. All the isolates (except Klebsiella pneumoniae) were sensitive to Psychotria microphylla. The highest sensitivity (7.0 mm) with ethanol extract of the herb was observed against Pseudomonas aeruginosa, closely followed by Salmonella Typhi (5.0 mm) and then Escherichia coli and Staphylococcus aureus (4.0 mm each). Although the herb showed a wider range of antimicrobial activity against the tested isolates than the mushroom, Klebsiella pneumoniae was sensitive (6.0 mm). The herb-mushroom extract combination produced a better antimicrobial activity against the isolates with a very high sensitivity of 16.0 mm recorded against S. aureus as compared to the highest sensitivity (10.00 mm) produced by Ampiclox against S. Typhi. The activity of Pleurotus sp was independent of the extract (p-value=0.189), meaning that the difference in zones of inhibition in relation to extract types was not significant (p>0.05). P. microphylla activities was dependent on the type of extract (p-value=0.031). ); that is, the difference in zones of inhibition produced by P. microphylla in relation to extract types was significant (p<0.05). The most efficient ratio of synergy was the 1:2 ratios which involved one part of Pleurotus species and two parts of P. microphylla.
Conclusion: The synergistic effect produced by Psychotria microphylla and Pleurotus species holds a good promise in the treatment of infections caused by tested bacteria and should be harnessed and patented.