Human Microbiome Flashcards
Oily (sebaceous)
Cutibacterium acnes
Moist
Staphylococcus spp
corynebacterium spp.
Dry
Cutibacterium acnes
Streptococcus spp.
Fungi (Lower numbers than bacteria)
- Malassezia spp. (wide distribution)
- Aspergillus spp. (foot)
- Cryptococcus spp. (foot)
Changes-children
– Increased Staphylococcus-associated atopic dermatitis
Changes-adults
Increased Malassezia-associated tinea versicolor
changes- staphylococcus aureus carriage
– associated with S. aureus bloodstream and surgical infections.
(Nares)
Changes- CoNS (coagu negative staph…)
CoNS may be protective against Staphylococcus aureus skin infections
changes- cutibacterium acne and corynebacterium striatum
might enhance the virulence of Staphylococcus
aureus
amplicon
amplify marker region by use of universal primers
whole genome metagenomic
fragment genomic DNA from bacteria, fungi, viruses, and host
acne
At puberty there is increased sebum secretion which correlates with clinical symptoms. Severity
is associated with C. acnes in follicles and formation of biofilms. Certain strains of Cutibacterium
acnes are associated with more severe inflammation. The severity may be associated with the
amount of porphyrins produced by specific strains and B12 supplementation may promote acne
atopic dermatitis
Current thinking is that exposure to Staphylococcus aureus in early life Is necessary to educate
the immune system about this potential pathogen. Microbial dysbiosis is associated with the
onset of atopic dermatitis and this disease is associated with overabundance of Staphylococcus
aureus and other Staphylococcus spp. It is possible that early administration of targeted
antibiotic therapy, can correct the dysbiosis and eliminate skin inflammation.
Diabetic foot infection
• Wounds are associated with a change in skin condition and microbiome.
• ulcers and other wounds are common in diabetic lower extremity. Patients with a short
duration shallow ulcer tend to have abundance of Staphylococcus spp., especially S. aureus.
Those with deeper ulcers that have persisted for weeks to months have a higher abundance of
Gram-negative bacteria and aerobic bacteria.
• Poor glycemic control is associated with increased abundance of Staphylococcus spp. and
Streptococcus spp.
• Chronic wounds are associated with poor outcomes and increased polymicrobial biofilms of
bacteria and fungi
oral and gastrointestinal tract
- The GI tract is an externally exposed organ with a surface area > 200 m2
- Four major phyla make up 98% of the microbiota: Firmicutes, Bacteroides, Proteobacteria and
Actinobacteria. - Unfavorable alteration of microbiota composition is termed dysbiosis and may contribute to diseases:
inflammatory bowel diseases, irritable bowel syndrome, gastritis, peptic ulcers, gastric or colon cancer.
stomach
• The stomach is a very harsh environment for microorganisms primary due to pH.
• Bacterial counts are in the range of 100 to 1000 per gram
• About 50% of population is infected with Helicobacter pylori. This agent produces urease which
provide local protection from acid. Helicobacter pylori is associated with gastritis, peptic ulcers
Ph.Pr. 860d Infectious Diseases Therapeutics Fall 2021
Nix – revision 8/23/2021
gastric B cell lymphoma, and gastric adenocarcinoma. The organism may also play a role in
several immune disorders
jejunum
• Bacterial density ranges from 1000 to almost 10,000,000 cells per gram. The bacterial genome
equivalents range from 1 x 105 to 3 x 107 per gram.
• 28% of microbiota represented by Streptococcus
• E. coli (6.5%) is most prevalent Proteobacteria and just over 20% are from this Phylum
• 12% is Prevotella and <1% Bacteroides
colon
57% of sequences were classified as Firmicutes –Clostridium clusters and anaerobic organisms are
predominant. Proteobacteria only present a small percentage and E. coli is the most prevalent in that
group. About 30% are placed in the Bacteroidetes class.
Presumed “good” bacteria that maintain the intestinal immune homeostasis
• Faecalibacterium prausnitzii
• Bacteroides spp.
• Akkermansia
• Lactobacillus spp.
• Bifidobacterium spp
colon- rifaximin
useful for irritable bowel syndrome. Treatment will reverse mucosal inflammation and
barrier dysfunction evoked by chronic stress. Rifaximin increase abundance of Lactobacilaceae and
reduces segmented filamentous bacteria
colon- Dysbiosis
s associated with many diseases ranging from inflammatory bowel diseases to autoimmune
disorders to anxiety and depression. At this point, for most of these, it is unclear whether the dysbiosis
plays a role in the pathogenesis of these disorders or is a consequence of these disorders. Studies aimed
at correcting the dysbiosis are ongoing or planned.
colon-Segmented filamentous bacteria
are anaerobic, unculturable bacteria that reside in the gut of humans
and most animals. They appear to be involved in Th 17 and regulatory T-cell activity and autoimmune
disorders such a psoriasis and inflammatory bowel diseases
colon-fungi
i are found in the colon and they are mostly “passing through”. Most of them can be found in the
oral cavity or in food. However, there are situations where the relative abundance of Candida increases
due to dysbiosis.
women-lactobacillus spp. healthy
Healty women have a predominance of Lactobacillus spp. in the vagina.
women- candida
Candida colonization is common but not considered normal flora. Most of this would be C. albicans and
based on screening of asymptomatic women, Candida is found in 10-55%
