Unravelling the consequences of the bacteriophages in human samples

Abstract

Bacteriophages are abundant in human biomes and therefore in human clinical samples. Although this is usually not considered, they might interfere with the recovery of bacterial pathogens at two levels: 1) by propagating in the enrichment cultures used to isolate the infectious agent, causing the lysis of the bacterial host and 2) by the detection of bacterial genes inside the phage capsids that mislead the presence of the bacterial pathogen. to unravel these interferences, human samples (n = 271) were analyzed and infectious phages were observed in 11% of blood culture, 28% of serum, 45% of ascitic fluid, 14% of cerebrospinal fluid and 23% of urine samples. The genetic content of phage particles from a pool of urine and ascitic fluid samples corresponded to bacteriophages infecting different bacterial genera. in addition, many bacterial genes packaged in the phage capsids, including antibiotic resistance genes and 16S rRNA genes, were detected in the viromes. Phage interference can be minimized applying a simple procedure that reduced the content of phages up to 3 logs while maintaining the bacterial load. this method reduced the detection of phage genes avoiding the interference with molecular detection of bacteria and reduced the phage propagation in the cultures, enhancing the recovery of bacteria up to 6 logs. Bacteriophages (phages), viruses that infect bacteria 1 , are probably the most abundant entities in the world 2. The abundance of phages in the human body is beginning to be envisaged as having a critical influence on human health. The ability of phage communities to modify and regulate bacterial communities 3,4 suggests that phages are to some extent responsible for the homeostasis of the microbiota 5,6. Phages can contribute to bacterial genomic plasticity by horizontal gene transfer (transduction) 7,8 , which may benefit the metabolism 9 or affect the virulence of the bacterial host 10,11. Some phages produce transducing particles consisting of phage capsids that carry only bacterial DNA 12,13 , these transducing particles or elements similar to gene transfer agents (GTAs) 14 are thought to be mechanisms used by bacterial cells to spread their own genomic content 12. The existence of phages in human biomes presupposes their presence in human samples and their contamination of laboratory cultures initiated from these samples 15. This interference can be envisaged at two levels: 1) phages may propagate in enriched liquid culture media (used to enhance analytical sensitivity and selectively propagate the pathogen) by infecting bacteria (the pathogen targeted for isolation) and causing their lysis during the process; and 2) phages can transport bacterial DNA, including virulence genes such as toxins 16 , antibiotic resistance genes (ARG) 11,17,18 or bacterial 16S rRNA genes 18. If any of these genes are targeted by molecular methods, positive results can be a confounding factor in the interpretation of results 19. The confirmation of phage interference in microbiological diagnosis, as envisaged in prev...

The True Host/s of Picobirnaviruses

“…On the other hand, certain observations with PBVs are reminiscent of eukaryotic viruses, such as (i) viremia in a sick horse and respiratory tract infections in cattle, humans, monkeys and pigs, (ii) immune response in a rabbit that was temporally associated with PBV excretion, and (iii) autoproteolytic processing of the PBV capsid protein and liposome-perforating capacity of viral particles (10,22,24,(53)(54)(55)67). However, similar findings have also been reported for bacteriophages:(i) bacteriophages have been detected in blood (phagemia) and respiratory samples, (ii) immune responses have been raised against prokaryotic viruses, and (iii) autoproteolytic capacities have been demonstrated for bacteriophages (68)(69)(70)(71)(72).…”

Identification of bacteriophages in the vagina of pregnant women: a descriptive study

“…Multiple phage families have been identified in the gastro‐intestinal tract, the oropharynx and the skin in almost all individuals examined 1–5 . They have also been detected in blood, ascites fluid, cerebrospinal fluid and urine 6 . Phages can replicate within their bacterial host followed by cell lysis and the release of new progeny phages to infect other cells (lytic cycle).…”

Characterizing Phage-Host Interactions in a Simplified Human Intestinal Barrier Model

“…Another finding was that phage A2 could translocate across the epithelial barrier in our model ( Figure 6 B). This finding gives additional weight to the ever interesting awareness that phage can cross eukaryotic cell barriers giving explanation to their detection in tissues and organs of the human body [ 65 , 66 , 67 ]. In summary, our model indicates the Enterococcus phage A2 (a member of Herelleviridae ) has a potential therapeutic value against E. feacalis infection in an intestinal epithelium-like environment.…”