Calling for backup

Antibiotic resistance is possibly one of the biggest crises we face in the 21^st century, as we are fast running out of effective cures and treatments for bacterial diseases. This is true not just for medicinal uses, but it is also a huge problem faced by the aquaculture and farming industries. Consequently, scientists are desperately looking for new effective ways to treat, or even better, prevent diseases. One of the major fields that has stemmed from this is phage therapy, which involves using various types of phages (often in combination – a phage ‘cocktail’) to reduce infectious bacterial populations.

Phage therapy has had some promising results so far, with many phages detected that are able to successfully reduce the populations of harmful bacteria, however efficiency varies, and there is still the worry that the bacteria will develop a resistance. For both of these reasons, this study looked at the effects of phage therapy with the addition of lysozymes. Using Vibrio parahaemolyticus as the target bacteria, the team tested the efficiency of 3 different Vibrio phages (VP-1, VP-2 and VP-3) both alone, and alongside lytic enzymes isolated from chicken eggs, of all places. The results were surprisingly positive, finding that in all 3 cases, adding these lytic enzymes increased the efficiency of bacterial reduction by the phages.

As can maybe be expected, each phage reacted slightly differently to the addition of these lytic enzymes, though all reacted positively. VP-1 in the presence of lytic enzymes showed bacterial inactivation at a rate almost 7-fold higher than the inactivation achieved when using the phage alone, and VP-2 + lysozyme showed a 2 times increase to the phage only treatment. The lysozymes seemed to have a lesser effect on VP-3, and actually worked better when a lower concentration of the lysozyme was added. However, VP-3 showed the highest bacterial inactivation of all 3 phages when they were being used alone, so it is likely that the limited effects of the lysozymes is because this phage is already highly efficient.

When looking into the effect of lytic enzymes on bacterial populations, and their antibacterial properties, it seems that there is already quite a lot of work being done in this area. While this experiment showed that using lysozymes on their own had no significant effect on bacterial populations, many other scientists seem to think that the exogenous addition of lysozymes could have key antibacterial results. This paper suggests that one of the positives of using lysozymes alongside phages is the slowing of bacterial resistance, as this combination leads to faster bacterial inactivation. I think this is hugely important considering our current position and dilemma with antibiotic resistance. I think an interesting next step would be to combine tried and tested ‘phage cocktails’, possibly with cocktails of lysozymes, to see if the effects can be heightened even further.

L. Mateus, L. C. (2014). Effect of lysozyme addition on the activity of phages against Vibrio parahaemolyticus. Aquaculture, 125-129.