Abstract:
Mankind is confronted by the outbreaks
of highly virulent and
multi-drug resistant pathogens. The
outbreak strains often belong to wellknown
disease-associated species belonging
to genera such as Salmonella,
Klebsiella and Mycobacterium, but even
normally commensal and environmental
microorganisms may suddenly acquire
properties of virulent bacteria and cause
nosocomial infections. The acquired virulence
is often associated with lateral
exchange of pathogenicity genomic
islands containing drug and heavy metal
resistance determinants. Metal ions are
used by the immune system of macroorganisms
against bactericidal agents.
The ability to control heavy metal
homeostasis is a factor that allows the
survival of pathogenic microorganisms in
macrophages. In this paper, we investigate
the origin of heavy metal resistance
operons in the recent outbreak strains and
the possible routes which may lead to
acquisitions of these genes by potentially
new pathogens. We hypothesize that new
outbreak microorganisms appear intermittently
on an intersection of the nonspecialized,
genetically naïve strains of
potential pathogens and virulence factor
comprising vectors (plasmid and/or phages)
newly generated in the environmental
microflora. Global contamination of the
environment and climate change may also
have an effect toward the acceleration and
appearance of new pathogens.
