respiratory tract infections Flashcards
Nonmotile, nonsporeforming, catalase-negative cocci that occur in pair or chain.
They are widely distributed in nature.
streptococci
…… elaborate a variety of extracellular substances and enzymes.
Streptococci
The most common infection caused by ……… is streptococcal sore throat or pharyngitis.
β-hemolytic S. pyogenes
S. pyogenes adheres to the pharyngeal epithelium by means of ………. surface pili and by means of…….. in encapsulated strains.
lipoteichoic acid-covered
hyaluronic acid
Local infection of the superficial layers of skin, especially in children.
Streptococcal pyoderma
viruses, mycoplasma, rickettsiae and fungi can all cause ….
lower respiratory
tract infections
How microbes gain access to the lower respiratory tract?
• Inhalation
• Aspiration of the normal flora of the upper respiratory tract
• Extension of upper respiratory tract infections
• Blood spread from other infected areas (less common)
Involvement of one lobe. The formed exudate clots in the alveoli rendering them solid (consolidation). Infection may spread to adjacent alveoli but limited by anatomic barriers of lung segments/ lobes
Lobar pneumonia:
Involve the small airways→ spread throughout the lung → patchy consolidation
Bronchopneumonia
Invasion of lung interstitium . Characteristic of viral pneumonia
Interstitial pneumonia
necrotizing pneumonia) Cavitation & destruction of lung parenchyma
D. Lung abscess
ØStaphylococcus aureus
Ø Pseudomonas aeruginosa
ØKlebsiella pneumoniae
Ø Acinetobacter baumanii
Hospital Acquired Pneumonia
Most common pathogens:
Morphology :Gram positive cocci in pairs, capsulated
Culture characteristics:
Alpha hemolysis on blood agar, Optochin sensitive
Streptococcus pneumoniae
Morphology:
Gram negative pleomorphic coccbacilli may be capsulated
Culture characteristics:
Grow on chocolate agar
Confirmation by factors X V requirement
Haemophilus influenzae
Morphology:
Gram negative bacilli Capsulated
Culture characteristics:
Lactose fermenting pink colonies on MacConkey’s agar
Biochemical reactions
Oxidase negative
Klebsiella pneumoniae
caused by Mycobacterium
Tuberculosis
Legionella is a genus of pathogenic Gram-negative bacteria that includes the species …..
causing legionellosis
L. pneumophila
….. live in water (primarily) and soil, can live inside protozoa
Legionella bacteria
• Stagnant water (dead legs in plumbing)
Warmer water (prefers: 77°F-108°F)
• Presence of organic matter
• Absence of residual disinfectant
Legionella Favorable conditions:
• A sever atypical pneumonia like infection
• Infection
Legionnaires disease
• A mild flu like illness
• Allergic reaction to live/dead Legionella + endotoxins from
non Legionella bacteria
Pontiac Fever
Increased Legionella antibodies with no symptoms
Asymptomatic Legionella
growth on hot water pipe growth on plastic tubing growth on cooling tower
pipe
Biofilm
Legionella detection methods
PCR/qPCR
Fluorescent in situ hybridization (FISH)
Enzyme-Amplified Electrochemical Detection with DNA probe
…on BYCE GVPC agar
L. pneumophila
