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To date, approximately 1400 species of human pathogens have been identified, including viruses, bacteria, fungi, protozoa, and helminths. As the Earth Microbiome Project advances, this number is expected to raise dramatically.
These pathogens cause16 million deaths each year, and this situation is predicted to worsen in the future.
Bacterial metabolism is crucial for both the virulence and the survival of pathogens within a host. Furthermore, these pathogens have developed advanced metabolic strategies to manipulate host immune responses, thereby promoting infection
Acosta & Alonzo 3rd 2023 J Innate Immun 15: 782-803
Intracellular bacterial pathogens have developed ways to survive and multiply inside the host. They adjust their metabolism to cope with immune responses, environmental changes, and drugs.
Intracellular pathogens are largely or completely dependent on host nutrients
Pathogens undergo significant genetic adaptations when associated with the host
The success of bacterial pathogens relies on sophisticated strategies for scavenging nutrients from their hosts (“nutritional virulence factors’’)
Other pathogens compete effectively with the host for nutrients that are available as a result of normal host physiology
Pathogens comprised of viruses, bacteria, gut microbiome, and Parasites / Parasitism are a leading cause of ever-emerging diseases in humans.
Escherichia coli, Klebsiella pneumoniae, and Pseudomonas aeruginosa are part of the World Health Organization's Priority 1 group of pathogens. These bacteria are acknowledged as significant contributors to mortality associated with antimicrobial resistance (AMR).
Metabolites from pathogenic bacteria can signal between bacteria and hosts. This communication can enhance virulence. It helps in biofilm formation and activating virulence traits
Although the gut microbiome is generally symbiotic or commensal, some microbiome members become pathogenic under certain circumstances
Pathogenic Bacteria Especially when They Become Dominant = Pathobionts
Bacteria such as Escherichia coli, Fusobacterium nucleatum, and Helicobacter pylori can cause pathogenic reactions in the host
Enteric pathogens, Including a Diverse Plethora of Enteric Viruses, Cause Acute and Chronic Diseases
Pathogenic bacteria have evolved diverse mechanisms to counteract cell-autonomous immunity, which otherwise guards both immune and non-immune cells from the onset of an infection.
Pathogenic bacteria are overrepresented in the microbial databases
Pathogen-associated molecular patterns (PAMPs), which are motifs such as bacterial LPS and viral nucleic acid features
Most pathogenic bacteria exhibit remarkable metabolic flexibility, allowing them to adapt to various niches within their hosts and exploit available nutrients effectively
Pathogenic bacteria release metabolites to outcompete others
For example, some intracellular pathogens hijack autophagic or proteolytic cellular machinery to release amino acids that can be exploited as carbon and energy sources
There are also pathogenic species (Bad Guys (certain harmful bacteria)) such as Campylobacter jejuni, Salmonella enterica, Bacteroides fragilis, Vibrio cholera, and Escherichia coli, but in a low abundance (0.1% or less)
Salmonella and Shigella spp. are pathogens
Clostridia have the potential for harmful pathogenic effects
Indigenous pathobionts are e.g. Clostridium difficile and vancomycin-resistant enterococci
Pathogens impact health either directly by invading the host or by eliciting an acute inflammatory immune response.
Many foodborne bacterial pathogens, including the non-typhoidal serovars of Salmonella enterica (Salmonella ), directly or indirectly induce mammalian cell death
This paradigm of inflammatory immune responses is even more consequential in people who may be immunocompromised.
But of the domain Bacteria the bacteroidetes (phylum), Alfaproteobacteria (class), Betaproteobacteria (class), gammaproteobacteria (class), deltaproteobacteria (class), chlamydiae (phylum), Spirochaetes / Spirochaetota (phylum), clostridia (class), bacilli (class) and actinobacteria (phylum) in which known human pathogens exist
see also:
Antibiotic resistance
Bacteria & Carcinogenesis / Oncogenesis / Tumorigenesis
Bacterial Biofilm / Microbial Biofilm (BF)
Bacterial cellular morphologies
Bacterial Sensing / Quorum Sensing (QS) system
Bad Guys (certain harmful bacteria)
Enteric pathogens
Exometabolome
Glutathione
Opportunistic infections