Asikin Nur Bagian Biomedika Kedokteran Gigi FKG UGM

PENYAKIT INFEKSI

Objectives

2. Interaksi kompleks penyebab infeksi

3. Mekanisme patogenesis mikroorganisme

1. Definisi infeksi dan penyakit

Infection:

invasion or colonization and multiplication of microorganisms in body tissues

The presence of a particular type of microorganism in apart of body where it is not normally found

Usually caused by a pathogenic microorganism

Disease

Pathological condition that affects part or all of an organism, as a medical condition associated with specific symptoms and signs. Occurs when an infection results in any change from a state of health An abnormal state in which part or all of the body is not properly adjusted or incapable of performing its normal functions.

Pathogencity & Virulency

Patogenitas: kemampuan suatu mikro-organisme dalam menyebabkan penyakit

Virulensi: derajat patogenitas yang dinyatakan dengan jumlah mikroorganisme atau mikrogram toksin yang dibutuhkan untuk membunuh hewan percobaan

Interaction of Host - MO

Simbiosis: a relationship between two organisms in which at least one organism is dependent on the other

Interaction of Host - MO Comensalism: one of the organism benefits and the other is unaffected Ex. S. epidermidis (skin surface), corynebacteria (surface of eye), mycobacteria (ear and external genitals)

Mutualism: a type of symbiosis that benefits both organisms Ex. E. coli (synthesize vit K and B)

Parasitism: one organism benefits by deriving nutrients at the expense of the other Ex. Disease causing-bacteria

Opportunistic Microorganism:

Ordinarily do not cause disease in their normal habitat in a healthy person but may cause infection in different site/ environments Ex. - E.coli: urinary tract infection, pulmonary

infection and meningitis or organ abscesses

- Pneumocystis jirovecii: Pneumocystis pneumonia (compromised host)

Etiology of Infectious disease

Koch`s Postulates: 1. The same pathogen must be present in every case of the

disease.

2. The pathogen must be isolated from the diseased host and grown in pure culture.

3. The pathogen from the pure culture must cause the disease when it is inoculated into a healthy, susceptible laboratory animal.

4. The pathogen must be isolated from the inoculated animal and must be shown to be the original organism.

Exception to Koch`s Postulates:

Treponema pallidum --- syphilis, but virulent strains have never been cultured on artificial media.

Mycobacterium leprae --- leprosy, has also never been grown on artificial media.

Many rickettsial and viral pathogens cannot be cultured on artificial media because they multiply only within cells.

Clasification of Infectious Disease

Communicable disease --- contagious disease Ex: chicken fox, measles, genital herpes,

thypoid fever, TBC Noncommunicable disease

Ex: Tetanus: Clostridium tetani

How it behave whitin a host and population

Frequency of occurance:

Sporadic disease: occasionally Ex: Typhoid fever

Endemic disease: constantly present in a

population Ex: common cold

Epidemic disease: many people in an area

acquire a certain disease in short period Ex: influenza

Severity or duration of a disease

Acute Ex: influenza

Chronic

Ex: TBC, Hepatitis B

Subacute Ex: Sclerosing panencephalitis

Latent Ex: Herpes: Varicella

Extent of Host Involvement

Local infection: (limited, small area) Ex: Boils and abscesses

Systemic infection: (spread throughout the

body) Ex: Measles

Focal infection: (enter blood or lymphatic vessel

and spread to other part od body) Ex: Endocarditis caused by oral bacteria

Primery Infection: an acute infection that causes the initial illness

Secundary Infection: caused by opportunistic

pathogen after the primary infection

The state of host resistance:

Transmission of Disease Contact Transmission:

Direct Transmission: hepatitis A, Staphylococal infection Indirect Transmission: hepatitis B Droplet Transmission: influenza

Vehicle Transmission: salmonela infection Vector Transmission: typhoid fever (feces)

Development of Disease

Tortora et al 2013, Microbiology An Introduction

How Bacteria Develop Infection

Generate a biofilm 90% of infection cases are related to

biofilm formation

Biofilm is 1000 X stronger than a planktonic

mode

BIOFILM

Generate a biofilm 90% of infection cases are related to

biofilm formation Biofilm is 1000 X stronger than a planktonic

mode

BIOFILM

Monroe D., et al. Bacterial Biofilms, PLOS Biology Vol. 8 No.11

Biolm model developed by S. intermedius at the presence of Extracellular DNA

Biofilm development Cells + DNA

Dispersal

Cells only Adherence Microcolony

Brain and liver abscesses caused by oral infection with S. intermedius

Wagner et al, Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2006; 102: e21-e23

A large liver abscess lesion

Panoramic radiograph showing periodontal lesions near the upper right and left molar

Brain abscess lesions in the left frontal lobe

Brain abscesses mimicking brain metastases. (A) Time course of T1/T2 weighted MR images, Gd: Gadolinium. (B) Papanicolaou staining and (C) gram staining of Bronchoalveolar lavage (BAL) material.

Erne et al, Lancet, 2010, 375: 2050

Brain abscess caused by lung infection with S. intermedius

References

1. Tortora G. J., Funke B.R. and Case C.J., 2013, Microbiology An Introduction, 11th ed., Pearson, Boston

2. Brooks G.F., Carrol K.C., Butel J.S., Morse S.A. and Mietzner TA., 2010, Jawetz, Melnick & Adelberg`s Medical Microbiology, 25th ed., The McGraw-Hill Comp. Inc.