CH 13 - Bacterial Diseases of the Respiratory System

3 main types airborne transmission

infected to susceptible by cough, sneeze, talk

• pathogen is attached to aerosolized mucus/saliva

dust contaminated with pathogen to susceptible person

from aerosols of water

• AC, jacuzzi sprays

upper respiratory system parts

sinuses

nasal cavity

auditory tube opening

pharynx

uvula

lower respiratory parts

epiglottis

larynx

trachea

pleurae

bronchus

bronchiole

part of respiratory system but not included in upper or lower

diaphragm

3 diseases upper

Streptococcal pharyngitis

Scarlet fever

Diphtheria

3 diseases lower

Tuberculosis

Bacterial pneumonias

Legionnaires’ Disease

inflammation related

usually 1st part affected gets inflamed

red swell pain hot

rubor tumor dolor calor

Strep throat causative agent

Streptococcus pyogenes

G+ cocci

strep throat transmission

airborne droplets

Strep throat symptoms

fever but no runny nose

red pharyngeal tissues from tissue erosion

purulent (pus containing) abscesses covering tonsils

strep throat pathogenicity/virulence factors 3 brief

M protein

Streptokinase

Streptolysin

M protein

Strep throat virulence factor

destabilizes complement (C3b) which would form MAC

retards phagocytosis

>60 types immunity difficult

adhesin specific to S. pyogenes

Streptokinase

strep throat virulence factor

breaks blood clots

allows bacteria spread through damaged tissues

Streptolysin

strep throat virulence factor

lyses erythrocytes, leukocytes, platelets

classification of streptococci 2

blood agar - differential hemolytic properties

lancefield groups

3 hemolytic properties

gamma (y) no effect no change

alpha (a) partial destruction - olive green cells

beta (b) complete destruction - clear zone around cells/yellow

lancefield groups

serological classification of streptococci based on cell wall antigens designated groups A-O

group streptococci worst for humans

Group A beta (b) hemolytic

most common Group A, b hemolytic

Streptococcus pyogenes

worst for humans

other conditions resulting from pathogenic streptococcus

scarlet fever

erysipelas

scarlet fever picture

bright red tongue

scarlet fever

strep throat w skin rash caused by S. pyogenes with a lysogenized bacteriophage

scarlet fever bacteriophage

temperate bacteriophage genome encodes erythrogenic toxin

scarlet fever red rash

caused by blood leaking through walls of capillaries damaged by toxin

shows most in soft skin areas of mouth, neck, chest

erysipelas

acute infection of dermal layer with streptococcus

erysipelas symptoms

painful reddish patches recur periodically at same body site

erysipelas patients

infants/people >30 with history strep throat

erysipelas image

face red patch sharpie outline

Diphtheria causative agent

Corynebacterium diphtheriae

G+ rod w metachromatic granules (stains dark)

remains partially attached after division > chinese lettering/angular/palisade arrangement

diphtheria transmission

inhaling respiratory droplets near tonsils

diphtheria pathogenicity

exotoxin encoded by lysogenic corynephage (virus only infect corynebacterium)

lysogenic corynephage’s exotoxin

diphtheria pathogenicity

composed of 2 polypeps bind human growth factor receptor on human cell

triggers endocytosis

destroys euk elongation factor blocking protein synthesis

diphtheria symptoms

pseudomembrane

made of mucus, dead cells, fibrous material

respiratory blockage fatal

diphtheria treatment

target toxin - antitoxin and antibiotics

supportive treatment - tracheostomy tube

diphtheria prevention

vaccinate with DTaP

toxoid for diphtheria

tuberculosis

lower respiratory disease caused by Mycobacterium tuberculosis

in developing countries most deaths than from any other bacterial disease

pic: copper tubes grow cells

mycobacterium unique characteristics (4)

cell wall has waxy lipid mycolic acid

slow growth could not know for decade

protection from lysis after phagocytosis, not crunchy

capacity for intracellular growth

Mycobacterium resistance to (4)

gram staining - only stained by acid fast procedure

detergents

many antimicrobial drugs

desiccation can survive in dried aerosol droplets for 8 months

2 types mycobacterium and disease they cause

Mycobacterium leprae: Leprosy/Hansen’s Disease

Mycobacterium tuberculosis: Tuberculosis

Tuberculosis transmission

M. tuberculosis inhaled into lungs

usually multiple exposures

see with chest xray

tuberculosis pathogenicity/virulence factors (2)

Mycolic acid - protects bacteria from lysis once phagocytosed

Cord factor - daughter cells remain attached to one another parallel alignment - inhibits migration neutrophils - toxic to mammalian cells

how tuberculosis starts

M. tuberculosis enters alveolus

• 10% ill in 3 months - cough, chest pain, fever, blood in sputum

• 90% only fever, weight loss

Tubercle formation - living bacteria, WBC, salts, fibrous materials

• detect with xray

secondary/reactivated tuberculosis

body loses fight - reinfection of lungs

tubercles break, spread in lungs

common w immunosuppression

disseminated/miliary tuberculosis

tubercle break and spread bacteria via lymph and blood

to liver, kidneys, meninges, bone marrow

leads to consumption of tissues

development tuberculosis in lungs

respiratory droplets enter alveoli

phagocytosed by macrophage but not lysed

incipient tubercle - few macrophages with bacterium - 1° infection

macrophages stick together try wall off

inside tubercle dies - caseous necrosis - tubercle surrounded by collagen fibers

ruptured tubercle spreads out - 2° reactivated tuberculosis

tuberculosis diagnosis/detection

detect M. tuberculosis in sputum sample - long time wait 3 weeks

tuberculin skin test - inject 0.1mL M. tuberculosis cell wall antigens (just parts)

xray detect tubercles

tuberculosis treatment

common antimicrobials ineffective

combination therapy used for months treat disease

• isoniazid, rifampin, ethambutol

• 6-9 months skip day lose pressure

  • DOT directly observed treatment

tuberculosis prevention

immunization with BCG vaccines where TB common

no vaccine in US

BCG bacille camille gueria - TB in cows

tuberculosis new threats

MDR-TB multi-drug resistant

XDR-TB extensively drug resistant

public health will track down

pneumonia

condition - inflammation of lungs - alveoli and bronchioles become filled w fluid

can be caused by bacteria, viruses, fungi

• most prevalent - pneumococcal pneumonia

some patients

• empynema - fluid in alveoli is pus

• pleurisy - pleurae inflamed tight hard breathe

pneumococcal pneumonia causative agent

Streptococcus pneumoniae

G+ capsule diplococcus

pneumococcal pneumonia transmission and symptoms

airborne droplets

fever, fatigue, hacking cough

usually only compromised affected - elderly, malnourished, smokers, viral infected, hospital patients, chemo, transplants

most often secondary disease

pneumococcal pneumonia pathogenicity/virulence factors (3)

capsule - prevents phagocytosis

pneumolysin

IgA protease

pneumolysin

virulence factor pneumococcal pneumonia

binds cholesterol in ciliated epithelial cells cause lysis of cells

IgA protease

pneumococcal pneumonia virulence factor

destroys IgA in mucus

damage to lining alveoli allows fluid enter lungs

primary atypical pneumonia causative agent

mycoplasma pnuemoniae

no cell wall - if put in liquid change shape

pleomorphic

one of smallest bacteria cause human disease

causes epidemics in crowded places

primary atypical pneumonia who affect

primary disease - occurs in healthy people

mainly high school and college students

primary atypical pneumonia symptoms

fever, dry hacking cough, fatigue

primary atypical pneumonia pathogenicity

bacteria attach base of cilia cause cilia stop beating

colonization destroys epithelial cells lining respiratory tract

primary atypical pneumonia treatment

erythromycin or tetracycline

not penicillin bc no cell wall

legionnaire’s disease

aka legionellosis

1976 outbreak among