Human Microbiome

Question 1

Oily (sebaceous)

Answer 1

Cutibacterium acnes

Question 2

Moist

Answer 2

Staphylococcus spp

corynebacterium spp.

Question 3

Dry

Answer 3

Cutibacterium acnes

Streptococcus spp.

Question 4

Fungi (Lower numbers than bacteria)

Answer 4

• Malassezia spp. (wide distribution)
• Aspergillus spp. (foot)
• Cryptococcus spp. (foot)

Question 5

Changes-children

Answer 5

– Increased Staphylococcus-associated atopic dermatitis

Question 6

Changes-adults

Answer 6

Increased Malassezia-associated tinea versicolor

Question 7

changes- staphylococcus aureus carriage

Answer 7

– associated with S. aureus bloodstream and surgical infections.
(Nares)

Question 8

Changes- CoNS (coagu negative staph…)

Answer 8

CoNS may be protective against Staphylococcus aureus skin infections

Question 9

changes- cutibacterium acne and corynebacterium striatum

Answer 9

might enhance the virulence of Staphylococcus

aureus

Question 10

amplicon

Answer 10

amplify marker region by use of universal primers

Question 11

whole genome metagenomic

Answer 11

fragment genomic DNA from bacteria, fungi, viruses, and host

Question 12

acne

Answer 12

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

Question 13

atopic dermatitis

Answer 13

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.

Question 14

Diabetic foot infection

Answer 14

• 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

Question 15

oral and gastrointestinal tract

Answer 15

• 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.

Question 16

stomach

Answer 16

• 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

Question 17

jejunum

Answer 17

• 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

Question 18

colon

Answer 18

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

Question 19

colon- rifaximin

Answer 19

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

Question 20

colon- Dysbiosis

Answer 20

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.

Question 21

colon-Segmented filamentous bacteria

Answer 21

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

Question 22

colon-fungi

Answer 22

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.

Question 23

women-lactobacillus spp. healthy

Answer 23

Healty women have a predominance of Lactobacillus spp. in the vagina.

Question 24

women- candida

Answer 24

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%