Differential Effect of Newly Isolated Phages Belonging to PB1-Like, phiKZ-Like and LUZ24-Like Viruses against Multi-Drug Resistant Pseudomonas aeruginosa under Varying Growth Conditions

Abstract

In this study, we characterize three phages (SL1 SL2, and SL4), isolated from hospital sewage with lytic activity against clinical isolates of multi-drug resistant Pseudomonas aeruginosa (MDR-PA). The host spectrum ranged from 41% to 54%, with all three phages together covering 79% of all tested clinical isolates. Genome analysis revealed that SL1 (65,849 bp, 91 open reading frames ORFs) belongs to PB1-like viruses, SL2 (279,696 bp, 354 ORFs) to phiKZ-like viruses and SL4 (44,194 bp, 65 ORFs) to LUZ24-like viruses. Planktonic cells of four of five selected MDR-PA strains were suppressed by at least one phage with multiplicities of infection (MOIs) ranging from 1 to 10−6 for 16 h without apparent regrowth of bacterial populations. While SL2 was most potent in suppressing planktonic cultures the strongest anti-biofilm activity was observed with SL4. Phages were able to rescue bacteria-infected wax moth larvae (Galleria melonella) for 24 h, whereby highest survival rates (90%) were observed with SL1. Except for the biofilm experiments, the effect of a cocktail with all three phages was comparable to the action of the best phage alone; hence, there are no synergistic but also no antagonistic effects among phages. The use of a cocktail with these phages is therefore expedient for increasing host range and minimizing the development of phage resistance.

Multisubunit RNA Polymerases of Jumbo Bacteriophages

“…The genome of jumbo phage AR9 infecting B. subtilis , a close relative of the PBS2 phage, was sequenced and shown to contain genes orthologous to the RNAP genes of phiKZ-like phages [ 18 ], suggesting that the PBS2 RNAP purified a long time ago [ 35 , 36 ] in fact belongs to this new group of non-canonical jumbo phage RNAPs. At the time of this writing, several dozens of jumbo phages encoding distant homologs of the β′ and β subunits are known [ 18 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 , 60 , 61 , 62 ]. They infect diverse bacterial hosts including members of Pseudomonas , Salmonella , Yersinia , Erwinia , Vibrio , Ralstonia , Bacillus , Aeromonas , Serratia , Klebsiella , Escherichia , and other genera [ 18 , 37 , 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , …”

Concentration-dependent reduction of planktonic- and biofilm-stateVibrio alginolyticusby the bacteriophage pVa-21

“…The characteristics of the Vibrio phage pVa-21 and its genome are expected to broaden the phiKZ-like phage library and help promote the application of bacteriophages in biofilm control to protect aquatic organisms from infection. In addition, as illustrated in a recent study [37], biofilm eradication by phiKZ-like phages in multidrug resistant bacteria suggests that the phiKZ-like phage, pVa-21, could also be used as a bio-control agent. The lytic effect of pVa-21 itself and the three distinct enzymes it possesses are expected to eradicate bacteria.…”

<p>How Phages Overcome the Challenges of Drug Resistant Bacteria in Clinical Infections</p>

“…No synergistic and no antagonistic effects of a cocktail was found with the three phages, however, the three-phage cocktail was as effective as the best phage alone. 96 Various studies demonstrated that different bacteriophages were able to reduce and lyse MDR P. aeruginosa in animal and in vitro conditions. 64,97,98 Additional animal studies show similarly promising results for MDR E. coli O25:H4-ST13, Vibrio parahaemolyticus, and S. aureus.…”