Baedah MadjidBaedah MadjidDepart. of Microbiology, Depart. of Microbiology,

Medical Faculty, Hasanuddin University.Medical Faculty, Hasanuddin University.20072007

Student must able to explain about the patho-mechanisms of infection

●● the factors affect the outcome of the infectionthe factors affect the outcome of the infection

Student must know how to explain about:Student must know how to explain about:

●● the stages of the bacterial pathogenesisthe stages of the bacterial pathogenesis●● the microbial factors involved in the the microbial factors involved in the onset and spread of the microbial infection.onset and spread of the microbial infection.• the strategy for the bacterial survivalthe strategy for the bacterial survival

●● the role of the bacterial normal flora

●● Definition : terms connectedDefinition : terms connected

●●Transmission of the InfectionTransmission of the Infection

● ● The The Stages of bacterial pathogenesisStages of bacterial pathogenesis

●●Factors affect the outcomes of the infectionFactors affect the outcomes of the infection

●● SummarySummary

● The Role of the Normal flora in Diseases

• • Normal Flora:Normal Flora: microorganisms that are frequently microorganisms that are frequently found in the various body sites in normal, healthy individuals.found in the various body sites in normal, healthy individuals.

•• Pathogens :Pathogens : - in medicine: the pathogen is any microorganisms capable - in medicine: the pathogen is any microorganisms capable of causing diseasesof causing diseases

- microbiology: being pathogen → microbemicrobiology: being pathogen → microbe must posses posses virulence factors (microbial pathogenicity)virulence factors (microbial pathogenicity)

•• Pathogen opportunisticThe non-pathogen bacteria → pathogen on susceptible host→ pathogen on susceptible host

● ● Pathogenesis = pathogeny:Pathogenesis = pathogeny: the organization & development of the infectionthe organization & development of the infection

●● Invasion:Invasion: the penetration of the host’s body by the penetration of the host’s body by microorganismsmicroorganisms

● Pathogenicity: the quality or state or being pathogenic; degree of pathogenic capacity.

Normal Flora: microorganisms that are frequently found in various body sites in normal, healthy individuals. Origin of human NF: environment : other human skin & mucous, water, air

The constituents and the numbers of the flora vary in different areas and sometime at different ages & physiologic states

■ One organism will always predominate in one anatomical site. This balance between microbes and the host tends to be stable.

• Mostly bacteria, & some fungi - Non pathogen

- Pathogen

Carrier state

• Bacterial normal flora :- - Resident NF:Resident NF:

-Transient NF:Transient NF: өө acquired from the environment acquired from the environment өө establish themselves briefly establish themselves briefly өө excluded by:excluded by: competitioncompetition host’s innate or immune defense mechanisms.host’s innate or immune defense mechanisms.

strain that have an establish niche at strain that have an establish niche at one of the body sitesone of the body sites

Ecology is a science concerned with the inter- relationship of organisms and their environment.The environment of an organism is the product of the presence and activities of other organisms that inhibit it is of nonliving chemical and physical forces.

The organisms tend to segregate and to becoe adapted to a particular habitat or environment niche.

That product are from : - other microorganisms - the host

Host - NF relationship → symbiotic :living animals/human use as habitats by other organisms → can be grouped as:■ Commensalisms : one species use the one species use the body of body of other larger speciesother larger species Mutualism: provide reciprocal benefits for the two organisms involved. Parasitism : benefits only the parasite.

Mouth flora plays mayor role in dental carries.

■ ■ Flora that reach sterile sites may cause disease: - E. coli → urinary bladder → UTI - Perforation of the colon from rupture a diverticulum or a penetrating abdominal wound → feces into peritonium → peritonitis caused primarily by facultative members of the flora.

Mouth flora may reach heart valves by transient bacteremia → colonized a previously damaged heart valve.

Ammonia production and bypass lead to Ammonia production and bypass lead to hepatic encephalopathy. hepatic encephalopathy.

Compromised immune system → opportunity for invasion ↑ → opportunistic pathogen Non-specific toxic effects of colonic flora are postulated Blind-loop overgrowth may cause fat mal- absorption and B12 deficiency. Colonization of jejenum occur in sprue.

•Priming of Immune systemSterile animal has little immunity to infection

•Exclusionary effect- Lactobacilus vaginal flora → protect host against transmitted N. gonorrhea- Exclusionary effect makes entrance of pathogens more difficult

• Production of Essential Nutrients-Help food digestion- Produce some vitamins

1.1. Contamination → port the entry: Contamination → port the entry: epithelium cellepithelium cell

2. Attachment to host cellsAttachment to host cells = adherence3. Invasion Invasion = Penetration

4. Multiplication5. DisseminationDissemination

6. Elimination

Progression

Resolution

Site of Microbial Contamination

Port the Entryor

Skin & Mucous

Transmission

• Exogenously♪ Human to human:- direct contact - Non-direct contact- Blood-borne- Vertical

♫ Nonhuman to human

♪ Human to human:-Direct contact : Gonorrhea- Non-direct contact : Dysentry- Blood-borne : Syphilis- Vertical (mother to her baby): ▪ Transplacental : Triponema pallidum Cytomegalovirus ▪ At time of birth : Chlamydia trachomatis Neisseria gonorrhoe ▪ Breast milk : Staphyloococcus aureus Cytomeglovirus

♫ Nonhuman to human ● Soil source : Tetanus ● Water source : Legionnaire’s disesase ● Animal source : ▪ Directly : Cat-scratch fever ▪ Via insect vector : epidemic typhus ▪ Via animal excreta : - Lisa (dog’s saliva) - Leptospirosis (rat’s urine) ● Fomite source : Staphylococcal skin infection

1.1. Contamination → port the entry: Contamination → port the entry: epithelium cellepithelium cell

2. Attachment to host cellsAttachment to host cells = adherence

receptorreceptor

Bacteria :Bacteria :

adhesin adhesin

Host epithel:Host epithel:

Pili = fimbriae Non- fibrillaefibrillae

- Pilli or fibrillae- Pilli or fibrillae

- Afibrial adhesins- Afibrial adhesins

* * Lectin (carbohydrate-binding-protein)Lectin (carbohydrate-binding-protein) * Lipoteichoic acid* Lipoteichoic acid * Fibronectin-binding-protein* Fibronectin-binding-protein * M-protein* M-protein * Outer membrane protein* Outer membrane protein * Polysaccharide capsule* Polysaccharide capsule

1. Contamination 1. Contamination

2. Attachment to host cellsAttachment to host cells

Colonization

Multiply

Carrier state (pathogen)

3. Invasion

1.1. Contamination → port the entry: Contamination → port the entry: epithelium cellepithelium cell

2. Attachment to host cellsAttachment to host cells

3. Invasion = PenetrationInvasion = Penetration

The penetration of the body of a host by a microorganism (Merriam’ Webster’s Medical Desk Dictionary)

. Environment potentially rich in nutrients. Environment potentially rich in nutrients . No competing microorganisme. No competing microorganisme

• Getting into cells → multiplicationGetting into cells → multiplication

• Resisting the degradative enzymesResisting the degradative enzymes

The advantages for intracellularThe advantages for intracellular (epithelia or PMN (epithelia or PMN cells) cells) pathogenspathogens : :

Bacteria can resist the degradative enzymes by:. elaborate enzymes → dissolves the surrounding membranes → replicate in within relative cyroplasm.. tolerate to initial endosome-lysosome fusion, or. inhibit the acidification of the endosomal vesicle → inhibit lysosomal fusion.

Bacteria & viruses inter the cell → reorganization of cytoskeleton → microbes in a membrane-bound vesicle in an acidic environment.

Mechanisms ExamplesSurvival the phagocyte & Complement attack Inhibition of chemotaxis Killing by phagocyte before ingestion

C5a peptidase by Str. pyogenesΑ-toxin and leukocidin by Staph. aureus

Avoiding ingestion (Phagocytose)) Bacterial capsule (Bacterial capsule (Streptococcus Streptococcus pneumoniaepneumoniae.).)LPS O Ag in Gr-neg rodsLPS O Ag in Gr-neg rodsCoating with IgA AntibodiesCoating with IgA Antibodies ((Neisseria meningitidisNeisseria meningitidis))M. protein (M. protein (Streptococcus Streptococcus pyogenespyogenes))

Mechanisms ExamplesSurviving within phagocytes Inhibition of phagosome fusion

(Chlamydia trachomatis)Escape phagolysosome (Listeria monocytogenes)Resistance to lysosomal product (Salmonella typhimurium)Inhibition of early host gene expression (M. tuberculose)

Antigenic variationAntigenic variation Shift and drift in influenza A virusShift and drift in influenza A virus

ToleranceTolerance Prenatal infectionsPrenatal infections

ImmunosuppressionImmunosuppression-Destroying lymphocytesDestroying lymphocytes- Proteolysis of antibodiesProteolysis of antibodies

Depletion of CD4Depletion of CD4++ T cells by HIV T cells by HIVIgA protease by IgA protease by H. influenzaeH. influenzae

Presence in inaccessible sitesPresence in inaccessible sites Latent infection in dorsal root Latent infection in dorsal root ganglia (Herpes simplex virus)ganglia (Herpes simplex virus)

1. Contamination → port the entry1. Contamination → port the entry2. Attachment to host cellsAttachment to host cells

3. InvasionInvasion4. Multiplication Metabolite excretion

Tissue Damage

Primary lesion

MECHANISMS OF CELL AND TISSUE DAMAGE BY MICROORGANISMS

Mechanism Examples

Direct damage by microorganisms

Production of toxins See next tableProduction of enzymes

Proteases, coagulase, DNAse,

Apoptosis HIV (CD4+ T cells), Shigella flexneri (macrophage)

Virus induced cytopathic effects: cell lysis formation of syncytium Inclusion bodies: - intracytoplasmic - Nuclear

CytomegalovirusRespiratory syncytial virus

RabiesHerpes viruses

Transformation Human papilloma-viruses type 16

MECHANISMS OF CELL AND TISSUE DAMAGE BY MICROORGANISMS

Mechanism ExamplesDamage via the host immune response

Cytotoxic T cells & natural killer lymphocytes

Production of measles rash

Autoimmunity Acute Rheumatic fever

Immediate hyper-sensitivity

Rashes associated with helminthic infection

Cytotoxic hyper-sensitivity

Cell necrosis induced by hepatitis B

Immune complexes Glomerulonephritis in malaria

Delayed type hypersensitivity

Tuberculosis granuloma

NO.NO. V. FACTORSV. FACTORS USED FORUSED FOR1.1. Protein pilli Protein pilli AttachmentAttachment2.2. Polysaccharide/Polypeptide Polysaccharide/Polypeptide

capsulecapsuleAvoiding ingestionAvoiding ingestion

3. 3. Protein MProtein M AttachmentAttachment4.4. Outer membrane proteinOuter membrane protein AttachmentAttachment5.5. ToxinToxin See “Toxin” tablesSee “Toxin” tables6.6. HyaluronidaseHyaluronidase SpreadingSpreading7.7. IgA proteaseIgA protease Breaking Surface IgABreaking Surface IgA8.8. DNAseDNAse Destroying host’s cellDestroying host’s cell9.9. CoagulaseCoagulase Avoiding ingestionAvoiding ingestion

Comparison of Properties Sources Certain sp of Gram-pos &

Gram-negativeCell wall of Gram-negative

Secreted from cell

Yes No

Chemistry Polypeptide LipopolysaccharideLocation of gene Plasmid or bacteriophage Bacterial chromosomeToxicity High LowClinical Effect Various effects Fever shockMode of action Various mode Includes TNF &

Interleukin-1Antigenicity Induce high titer Ab:

antitoxinPoorly antigenic

Vaccine Toxoids No toxoid or vaccines avaiable

Heat stability Destroyed rapidly at 60oC (except Staphyl enterotoxin)

Stable at 100oC for 1 hr

Typical diseases Tetanus, botulisms, diphtheria

Meningococcemia, sepsis by Gram-negative rods

Mode of Action of Exotoxin

1. As superantigen : Staph. aureus (enterotoxin & TSST), Clost. perfringens, Bacillus cereus, Strept. pyogenes (erythrogenic toxin)

2. Inactivates GTPases in enterocytes: Clost. difficile

3. Stimulates adenylate cyclase : Vibrio cholerae, toxigenic E. coli, Bordetella pertussis4. Inactivates protein synthesis: E. coli O157, C. diphtheriae5. Inhibits glycine release: Clost. tetani

Mode of Action of Exotoxins

9. Lecithinase cleaves cell membranes: Clost. perfringens

10. An adenylate cylase: edema factor of Bacilus anthracis

11. A protease: lethal factor of Bacilus anthracis

7. Inhibits chemokine receptor: Bordetella pertussis

6. Inhibits acetylcholine release: Clost. botulinum

8. Protease cleaves desmosome in skin: Staph. aureus (scalded skin syndrome)

The Biologic Effects of Endotoxins1. Fever : release of endogenous pyrogen (interleukin-1) from

macrophages

2. Hypotension, shock and impaired perfusion of essential organ: bradykinin-induced vasodilatator → membrane permeability ↑ & peripheral resistance ↓

3. Disseminated intravascular coagulation: activation of the coagulation system → thrombosis, petechial or purpuric rash and tissue ischemia → vital organ failure .

4. Activation of the alternative pathway of the complement: → inflammation and tissue damage

5. Activation of macrophages: phagocytic ability ↑, Ab production ↑ (ctivation of many clones of B lymphocytes)

EXAMPLES OF BACTERIAL TOXINSToxin type Sources Toxin Target Effects

Endotoxin (LPS, lipid A)

Gr- Bacteria Endotoxin Macrophage,Neutrophils, lymphocytes,Plasma components

Septic shock

Membrane disrupting toxins

Staph. aureus Α-toxin Many cells types

Tissue necrosis

L.monocytoges Listeriolysin Many cells types

Escape from the phagosome

Cl. perfringens Perfringoly-sin-O

Many cells types

Gas gangrene

A-B type toxins

Cl. tetani Tetano-spasmin

Synaptic transmission

Spastic paralysis

C. diphtheriae Diphtheria toxin

Many cells types

Paralysis

Vibrio cholerae Cholera toxin Intestinal cells

Profuse watery diarrhea

Super-antigen

Str. pyogenes Streptococcal pyogenic exotoxin

T. cells, macrophage

Fever, eruption, toxic-shock like syndrome

Staph. aureus Toxic shock toxin

T. cells, macrophage

Toxic shock syndrome

1. Encounter → entry1. Encounter → entry

2. Attachment to host cellsAttachment to host cells

3. InvasionInvasion

4. Multiplication

5. DisseminationDissemination

Directly

-hematogenously --lymphatogenously

IndirectlyIndirectly

Bacteria can be eliminated by:

1. Natural host defense:- Lysozyme and other enzyemes - Acid - Complement

2. Acquired host defense: - Antibodies

3. Antibiotics therapy

Symptomatic diseaseAsymptomatic = sub-clinic diseases

Depend on:1.1. The organism’s ability to breach host barrier & to The organism’s ability to breach host barrier & to evade destruction by innate local and tissue host defences.evade destruction by innate local and tissue host defences.

2.2. The organism’s biochemical tactics to replicate, to spread, to The organism’s biochemical tactics to replicate, to spread, to establish infection, and to cause disease.establish infection, and to cause disease.

3. The microbe’s ability to transmit to a new susceptible host.3. The microbe’s ability to transmit to a new susceptible host.

4. The host’s innate and adaptive immunologic ability to control 4. The host’s innate and adaptive immunologic ability to control and eliminate the invading microbes.and eliminate the invading microbes.

DOSE OF MICROORGANISMS REQUIRED TO PRODUCE INFECTION IN HUMAN VOLUNTERSMICROBEMICROBE ROUTEROUTE DISEASE-PRODUCING DOSEDISEASE-PRODUCING DOSE

Rhinovirus PharynxPharynx 200200

Salmonella typhi OralOral 101055

Shigella spp. OralOral 10 - 100010 - 1000

Vibrio cholerae OralOral 101088

Mycobacterium tuberculosis

InhalationInhalation 1 - 101 - 10

3. Pathogen:- Posses virulence factors- Opportunistic pathogen: NF or colonization of pathogens on carrier Environment bacteria

4. Outcomes of infection is depend on:- Pathogenicity of bacteria

- Dose of contamination

- Host defense mechanisms

1. Normal Flora2. Transmission of Bacteria

FURTHER READING Brooks, GF., Butel, JS., Morse, SA. Jawetz, melnick, & Adelberg’s

Medical Microbiology. 23rd Edition, International Edition, McGraw-Hill, Singapore, 2004.

Cohen, J. et al. Infectious Diseases, 2nd Edition, Mosby, Sydney, 2004. Inglis, T.J.J. Microbiology and Infection, a clinical core text for

integrated curricula with self-assessment, Churchill-Livingstone, Sydney, 2003.

Levinson, W. Review of Medical Microbiology and Immunology, 9th Edition, McGraw Hill-Lange, Singapore, 2006.

Joklik, WK., Willett, HP., Amos, DB., Wifert, CM. Zinsser Microbiology, 20th edition, Appleton & Lange, Connecticut, 1992.

Mims, C., et al. Medical Microbiology, 3rd Edition, Mosby, Sydney, 2004.

Nath, S.K., Revankar, S.G. Problem Base Microbiology, Saunders-Elsevier, Philadelphia, 2006.

Ryan, KJ., Ray, CG. Sherris Medical Microbiology, an Introduction to Infectious Diseases, McGraw-Hill, Singapore, 2004.

Strohl, W.A., Rouse, H., Fisher, B.D. Lippincott’s Illustrated Reviews Microbiology, Lippincott Wlliams & Wilkins, Maryland, 2001.

Virella G. Microbiology and Infectious Diseases, 3rd Edition, Edited., Williams and Wilkins, Baltimore, 1997.