Emerging Pathogens Flashcards by Rachel Sampson

Define emerging infectious diseases.

Infectious diseases that have newly appeared in a population or have existed but are rapidly increasing in incidence or geographic range or caused by one of NIAID category A,B,C priority pathogens

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Define opportunistic infections.

Infections occurring due to bacteria, fungi, viruses or parasites that normally do not cause a disease but become pathogenic when body’s defense system is impaired

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What are 3 reasons for pathogens emerging?

Development of new diagnostic tools
Increase in human exposure to bacterial pathogens
Emergence of more virulent bacterial strains & opportunistic infections

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What is ‘one health’?

Integrated, unifying approach to balance & optimize the health of people, animals & environment

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What are 4 examples of disease control & prevention?

Vaccination
Environmental sanitation
Vector control
Reduction of population growth

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How are pathogens detected in pts?

Culture based
Microscopic examination
Molecular methods (PCR/NGS/MS)

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What are 3 conventional techniques for environment screening?

Multiple tube fermentation
Membrane filters
Microscopic examination

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What are 4 advanced techniques for environment screening?

Immunological methods (ELISA)
Molecular methods (PCR/FISH)
Enzymatic methods
Emerging methods (biosensors)

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What is MALDI-TOF MS?

Matrix assisted laser desorption ionization-time of flight MS

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What is MS?

Analytical approach that measures the mass-to-charge ration of compounds & calculates its exact molecular weight

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What are 5 advantages of MALDI-TOF MS?

Fast diagnosis
Avoiding unnecessary antimicrobial use
Reduced morbidities & costs
Based on intact proteins
Low cost of analysis

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What are 3 disadvantages of MALDI-TOF MS?

Trained laboratory personnel
Identification of new species relies strongly on complete database
Initial investment in expensive equipment

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What are 6 characteristics of healthcare-associated-infections?

Unusual epidemiology & transmission
Medical environment
New infection sources & transmission ways
Another underlying disease
Strains emerging from microbiome
Subspecies level identification needed to define outbreaks & transmission

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What are 3 examples of HAI?

MRSA
VRE
Multi-drug resistant E. Coli

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What 4 pathogens are in the critical group of WHO bacterial priority pathogens?

Enterobacterales carbapenem - resistant
Enterobacterales 3rd gen cephalosporin resistant
Acinetobacter baumanii
Mycobacterium Tb rifampicin resistant

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What are 2 characteristics of emerging respiratory tract pathogens?

Most common opportunistic pathogens in nosocomial infections
Developing a high level of Ab resistance that involves multiple mechanisms

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What are the ESKAPE emerging respiratory tract pathogens?

Enterococcus faecium
Staphylococcus aureus
Klebsiella pneumoniae
Acinetobacter baumannii
Pseudomonas aeruginosa
Enterobacter spp.

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What can MALDI-TOF MS be used for?

Identifying resistance
Growth of bacteria directly on MALDI-TOF MS target (4-5h)
Identification of spectra directly

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What type of bacteria are emerging CF pathogens?

Opportunistic
Commensal

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What are 6 emerging CF pathogens?

MRSA - easy transmission
Nontuberculous mycobacteria - ubiquitous environmental organisms eg. M. abscessus complex
Achromobacter spp. - environmental, rare opportunistic eg. A. ruhlandii
Stenotrophomonas maltophilia - aquatic environmental reservoirs
Pandoraea spp.
E.coli - no transmission

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What are 7 characteristics of Mycobacterium abscessus?

Non-TB
Rapidly growing
Environmental (soil, water, animals, free living amoeba)
Opportunistic - concern in immunocompromised people
Increasing prevalence
Intrinsic & acquired resistance
IC proliferation & survival

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What was M. abscessus historically considered as?

Environmental contaminant

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What are 6 adaptations of M. abscessus?

Opportunity to colonise host
Adaptation to host environment -> pre-adaptation in amoeba & metabolic switch, genetics & acquirement of virulence factors
Developing transmission routes
Drug resistance
Niche specialisation
Dormancy

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What 2 ways does M. abscessus spread?

Transformation in true pathogen
Inter-human transfer (direct/environmental)

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What 2 pieces of evidence leads to evolution towards a pathogen?

Proof of person-to-person transmission Proof of incidence in individuals with no known underlying conditions

What 3 things need to happen to lead to evolution towards a pathogen?

Pre-adaptation in environment Intrinsic resistance to many Abs Co-colonisation with other species of opportunistic bacteria (acquire new VFs)

What are 4 non-mycobacterial VFs?

Phospholipase C MgtC MsrA ABC Fe(3+) transporters

What pathogen is the pharma industry becoming interested in?

Non-TB Mycobacteria

What is an example of an opportunistic pathogen?

Enterococcus spp

What are 3 sources of E. spp?

Gut colonization 7-10 days after birth Adulthood sources - certain food Environment - colonization of biotic & abiotic substances

What 4 infections can lead to pathogenic E. spp (mutagenic effects at sites of infection?

UTI sepsis ulcers catheter related

What happens in dysbiosis of E. spp?

Enterococcal overgrowth in epithelial cell -> biofilm -> virulent

What are 5 commensal roles of E. spp?

Immune homeostasis Produce bacteriocins against pathogens Role in digestion Block spread of putrefactive bacteria Lower cholesterol levels

What are 5 sources of E. spp in probiotics?

Biotherapeutics for chronic sinusitis Bio-preservatives Dietary supplementation for animals Starter cultures in dairy products After antibiotics

When does E. spp become pathogenic?

Nosocomial infections VF & resistance factors transmitted between species or genera by horizontal gene transfer Food spoilage Food poisioning

What are 6 therapy examples for emerging bacterial diseases?

Silver NPs Antimicrobial light therapy Antimicrobial peptides Abs Vaccines Bacteriophage therapy

What are 4 characteristics of AMPs?

Short, +vely charged, amphiphilic, diverse

What are AMPs?

Host defense oligopeptides produced by all organisms

What are 2 factors of AMPs MoA?

broad spectrum of activity interact with cell membrane - cell lysis

What are 8 mechanisms of synergy between AMPs & Abs?

Promoting bacterial absorption of Abs Change membrane permeability Interference with bacterial cell membrane Target LPS in gram -ve bacteria Destabilize LPS structure Inhibit metabolic pathways Inhibit drug resistant enzymes Block efflux pumps

What are 6 AMPs advantages?

Unlikely to induce resistance Broad range of action Rapid bactericidal activity Target poly-microbial infections Improve action of Abs Easy availability

What are 3 cons of AMPs?

Potentially toxic Unstable in presence of proteases Expensive to make

What are 4 light sources for ALT?

Xenon lamps Light emitting diodes Laser beams Fiber optics

What type of wave length are preferred in ALT?

Longer - deeper tissue penetration

How does ALT work?

uses a photosensitizer (PS)—a light-activated compound—combined with a specific light source to generate reactive oxygen species (ROS)

What 5 things does ROS do to the bacterial cell?

Cell membrane disruption Interrupted transmembrane electron transport Damage to proteins DNA damage Damage to ribosomes

What are 5 characteristics of an ideal PS?

Strong absorption peak Substantial triplet quantum yield High tissue selectivity No toxicity to human cells High stability

What are 4 natural PSs?

Curcumin Chlorophyll Riboflavin Chlorins

What are 5 advantages of ALT?

Broad spectrum of action No resistance after multiple sessions Used to support Ab therapy Non-invasive Low cost

What are 3 cons of ALT?

Sub-optimal uptake of PS by bacteria Lack of selectivity Short light penetration depths

How do silver NPs work?

Act by releasing Ag+ ions Less reactive than silver ions

What are silver NPs action dependent on?

Physical, chemical, thermal, electrical & optical properties (shape, size, concentration)

What do colloidal forms of AgNPs show?

Enhanced antimicrobial potential

What 4 ways are colloidal AgNPs synthesized by?

Chemical reduction Physical Biological Green methods

What 4 things do the released Ag+ ions do?

Generate ROS Disrupt electron transport & signal transduction pathways Disrupt cell wall, cell membrane, cellular DNA & proteins Inhibit planktonic cells & biofilms

What are 3 safety concerns of silver NPs?

Ag comparatively non- toxic/mutagenic compared to other metals Resistance against AgNPs Influence on microbiome

What 3 things can AgNPs do to cells?

Carcinogenesis & fibrosis Genotoxicty Cytotoxicty

What have AgNPs been used for?

Prevention on infection CF inhalation therapy M. TB, M. bovis & multiple drug resistant TB strains

What are 4 potentials of AI for emerging pathogens?

Combating Biofilm formation Ab discovery De novo drug designing Detection & monitoring

What are 3 current applications of AI?

Interpretation of antimicrobial susceptibility profiles - neural-network based app In silico drug design approaches for structure & ligand based design Virtual screening of drug candidates