This document provides information on common and less common organisms found at different body sites. It also lists some pathogenic organisms and their capsules. Some key points: - Staphylococcus aureus and epidermidis are commonly found on the skin and nose, while streptococci and corynebacteria are less common. - The oropharynx commonly contains streptococcus viridans and non-pathogenic neisseria, while the gingival crevices harbor various anaerobes. - The colon microbiota varies from bifidobacteria and lactobacilli in babies to bacteroides, prevotella, and eubacteria in adults. - The

9. Site Common Organisms Less-Common
Blood Sterile
Cutaneous Surface Staphylococcus Epidermidis Staphylococcus Aureus,
Corynebacteriae Streptococci, Yeasts
Nose Staphylococcus Aureus Staphylococcus Epidermidis,
Corynebacteriae Streptococci
Oropharynx Streptococcus Viridans Non-pathogenic Neiserria,
Haemophilus Influenzae, Candida
Gingival Crevices Anaerobes: Bacteroides, Prevotella,
Fusobacterium, Streptococcus,
Actinomyces
Stomach None
Colon (microaerophilic/
anaerobic)
Babies: breast-fed only:
Bifidobacterium
Lactobacillus, streptococci
Adult: Bacteroides/Prevotella Eubacterium, Fusobacterium,
Lactobacillus, gram-negative rods.
Vagina Lactobacillus Assorted streptococci, gram-negative
rods, diphtheroids, yeasts

10. Streptococcus Pneumoniae
Klebsiella Pneumoniae
Haemophilus Influenzae
Pseudomona Aeruginosa
Neisseria Meningitidis
Cryptococcus Neoformans
“Some Killers Have Pretty Nice Capsules”
Organisms with Capsules

11. “My Niece, Your Legion Lists Frances, Bruce and Salmon”
Mycobacterium Tuberculosis
Neisseria
Yersinia
Legionella
Listeria
Francisella
Brucella
Salmonella
Facultative Intracellular

12. Toxins
Endotoxin (Equivalent to
LPS)
• Gram – organisms
• Lipid A portion is the toxic part
• Over-activates the immune
system.
• Eg. Septic Shock w/gram -
Exotoxin
• Secreted proteins
• Gram +/-
• A-B toxin
(B binds to receptor) (A active)
• Cytolysins (lyse cells)

13. Toxin
Mechanism
Organism Toxin
Mechanism of
Action
Role in Disease
Protein Synthesis
Inhibitor
C. Diphtheriae Diphtheria toxin
elongationEF-2 (heart,
nerves, epithelium)
Inhibits eukaryotic protein
synthesis.
P. Aeruginosa Exotoxin A eEF-2 (liver)
Shigella Dysenteriae Shiga toxin Interferes with 60S
Ribosomal unitEHEC E. Coli Verotoxin (shiga-like)
Neurotoxins
C. Tetani Tetanus toxin (spastic)
Blocks inhibitory
transmitters of GABA
Inhibits neurotransmission
in inhibitory synapses
C. Botulinum
Botulinum toxin
(flaccid)
Blocks release of
acetylcholine
Inhibits cholinergic synapses
Cytolysin
C. Perfringens
α toxin
Lecithinase
Damages cell membranes,
myonecrosis
S. Aureus
Intercalates forming
pores
Cell membrane becomes
leaky

14. Toxin
Mechanism
Organism Toxin
Mechanism of
Action
Role in Disease
Super Ag
Staph Aureus TSST-1 Superantigen
Fever, shock, capillary
leakage
Strep Pyogenes Exotoxin A Similar to TSST-1
Shock, capillary leakage
and cardiotoxicity
cAMP increase
ETEC E. Coli Heat-labile toxin Adenylate cyclase by
ADP ribosylation of
GTP binding protein
Secretion of fluid and
electrolytes
Profuse, watery diarrhea
V. Cholerae Cholera toxin
B. Anthracis
Anthrax toxin
Capsule made of
Polypeptide
EF- edema factor, LF-
lethal factor,
Protective Antigen
Decreases phagocytosis
Causes edema and kills
cells
B. Pertussis Pertussis toxin ADP Ribosylates G1
Histamine-sensitizing
Lymphocytosis islet
activation

15. Big peptidoglycan layer
stains purple
THIN peptidoglycan layer
stains pink

16. ENDOSPORE
Present in Bacillus and Clostridium
Function: SURVIVAL

17. Bacterial Chromosomal DNA
About 2,000
genes
Bacterial Plasmids
Bacteriophage
Prophage (virus that infects bacteria) gets
inserted into the bacteria may synthetize
other proteins.
Gene products to make bacteria more
pathogenic- Lysogenic Conversion

18. It must find a homologous zone to
begin recombination and exchange
DNA. RecA is essential for this.
Integration of DNA, it’s an addition.
-Fertility factor
-Bacteriophage into a bacteria
-Movement and insertion of
transposons

19. Male Female
Male cell known as F+ due to
the fertility factor
• Sex Pili
• Genes that stabilize the pair
• Genes that direct DNA
transfer
• oriT (origin of transfer)
• IS – Insertion sequence
Female cell known as F-
They do NOT have fertility
plasmid.
At the end, the cell becomes an
F+ donor.

20. Transformation- Cells become able to bind short pieces of DNA and import them into the cell.
These are incorporated by homologous recombination
HFR conjugation- HFR cell tries to give all of his DNA to F- but stabilization doesn´t last
F- cell stays as a recipient and needs homologous recombination to express new plasmids.

21. Lysogenic Conversion
COBEDS= When 2 people share
a bed, someone gets a little bit
pregnant –by a phage
1. Cholera toxin
2. O antigen of Salmonella
3. Botulinum toxin
4. Erythrogenic exotoxins of S.
Pyogenes
5. Diphtheria toxin
6. Shiga toxin

22. Antimicrobial Agent Mechanism of Resistance
Penicillin and Cephalosporins Production of beta-lactamase, cleavage of beta-
lactam rings
Aminoglycosides Production of acetyltransferase, adenosyltransferase
or phosphotransferase.
Inactivation of drug by acetylation
Chloramphenicol Production of acetyltransferase, inactivation of drug
by acetylation
Tetracyclines Increased efflux out of cell
Sulfonamides Active export out of cell and lowered affinity of
enzyme
Vancomycin Ligase produces cell wall pentapeptides that
terminate in D-alanine-D-lactate, which will not bind
to the drug

23. Minimal
Inhibitory
Concentration
Minimal
Bacteriocidal
Concentration

24. DNA or RNA
Eg. Herpes Virus

25. Inhibited by Interferon
1
1. Attachment to host cell receptors.
2. Penetration
3. Uncoating (release of nucleic acid)
4. Macromolecular synthesis
• Early mRNA and protein synthesis
• Replication of the genome (DNA
go to the nucleus, RNA in the
cytoplasm)
• Late mRNA and protein synthesis
5. Post-translational modification of
proteins
6. Assembly of the new virus particles
7. Release (lysis of the cell or budding
out/fusion)
2
3
4
5
6
7
Prevented by Vaccination

26. Virus Target Cell Receptor on Host
HIV TH cells, macrophages,
microglia
CD4 (plus CCR5 –
macrophage and CXCR4 –
T cells)
EBV B cells CD21 = CR2
Rabies Neurons Acetylcholine receptor
Rhinovirus Respiratory epithelial cells ICAM-1 (85%)

27. Translated in the nucleus
Must bring RNA polymerase
inside the virion
HIV
Uses no intermediate
EXCEPTION
Hepatitis B parental
genome is dsDNA,
uses ssRNA to make
dsDNA

28. Start
Start
Start
Start
End
Smallpox
Measles
Chickenpox
Hepatitis B or C
Acute Infection
Acute Infection
w/ rare
complication
Latent Infection
Chronic
Infection
You recuperate or die
Intact virus not made
Some viral proteins
maintain latency
Shingles
SS Panencephalitis
Viral Shedding

29. Age will be important
for the diagnoses of
viruses

30. Marker Terminology
HBsAg Found during acute disease and persistent
infections
More than 6 months = Chronic
HBsAb Provides immunity to HBV -Vaccine
HBcAb IgM - Important for recent infection
Useful during window period
IgG – Recuperated from infection
HBeAg Correlates with active viral production and
infectivity
HBeAb Suggest lower risk of transmission

33. Attachment protein
• Interacts with CD4 and
coreceptors
Fusion protein
to host cell
P24 – antibodies
are detected for
diagnosis
Produces
dsDNA provirus
Decreases CD4 and MHC I
expression,
• Required for progression to
AIDS.
Responsible for virulence

34. Disease Agent Begin Prophylaxis Discontinue
Prophylaxis
Pneumocystis Jiroveci <200 CD4 >200 for 3-6 months
Toxoplasma gondii <100 CD4 >100 for 3-6 months
Histoplasma capsulatum <100 CD4 (endemic area) Continue
Mycobacterium Avium <50 CD4 >100 for 3-6 months
Cytomegalovirus <50 CD4 >150 for 3-6 months
Cryptococcus neoformans <50 CD4 Continue

35. All fungi are:
• Heterotrophic
Requires organic carbon
• Saprophytic or saprobic
Fungus living on dead organic material
• Parasitic
Fungus living on another living organism
Mold in the cold, yeast in the beast.
-Dimorphic Fungi
Body
Heat
Changes
Shape

37. Fungi

38. Histoplasma
Coccidioides
Blastomyces

39. Cause paroxysms