14. diseases of respiratory and nervous systems Flashcards
what bacteria causes strep throat/streptococcal pharyngitis?
Streptococcus pyogenes (gram-positive, encapsulated, chain like cocci arrangement)
streptococci pyogenes is a ______________ Streptococci (GAS)
group A beta-hemolytic streptococci (GAS)
the different serotypes of GAS produce a number of virulence factors such as:
- extracellular enzymes (collagenase and streptokinase) that break down host molecules and cause the infection
- the cytolysins streptomycin O and streptolysin S which kill host leukocytes
- capsules and M protein, which limits phagocytosis and facilitate attachment to host cells
what two areas can the strep bacteria act on>
throat causing pharyngitis
tonsils causing tonsilitis
how is S. pyrogens spread?
by droplets of saliva or nasal secretions.
what is the incubation period of strep?
2-4 days
what are the symptoms of strep throat?
fever higher than 38, intense pharyngeal pain, swollen dark red palatine tonsils often dotted with patches of pus, swollen submandibular lymph nodes
some strains of group A streptococci produce this toxin. this toxin attacks the plasma membranes of capillary endothelial cells and leads to scarlet fever, a disseminated fine red rash on the skin, and strawberry tongue, a red rash on the tongue
erythrogenic toxin
in few cases, 1-4 weeks after an acute streptococcal infection, a poststreptococcal disease could occur and cause _________ and _____________
glomerulonephritis and rheumatic fever
what bacteria causes diphtheria?
Corynebacterium diphtheriae (club shaped, gram positive rods)
this is typically a respiratory infection of the oropharynx characterized by a sore throat, neck swelling, and blockage of the respiratory pathways
diphtheria
C. diphtheriae produce this toxin which blocks host cell protein synthesis, and leads to the death of the epithelial lining and inflammatory response
diphtheria exotoxin
in diphtheria, there is an accumulation of a greyish exudate consisting of dead host cells, pus, red blood cells, and infectious bacteria results in the formation of a ________
pseudomembrane (diphtheric patch)
true or false: there is a vaccine for diphtheria
true - the DPT vaccine
this is one of the deadliest infectious diseases in human history
tuberculosis `
what is the causative agent of TB?
Mycobacterium tuberculosis (acid-fast, gram positive, rods)
how does M. tuberculosis infect an individual?
M. tuberculosis infects the lung tissue and is spread bye inhalation of respiratory droplets or aerosols from an infected person. after inhalation the bacteria enter the alveoli where the cells are phagocytize by macrophages. the bacteria can survive and multiply within these phagocytes because of protection by the waxy mycolic acid in their cell walls.
the infection would cause an inflammatory response and an accumulation of what white blood cells?
neutrophils and macrophages
these are small round lesions surrounded by layers of macrophages and T-lymphocyes
granuloma
what is another name for granulomas, which are calcified structures that are visible on chest xrays
ghon complexes
granulomas may enlarge and form ________, that rupture and the bacterial cells invade pulmonary capillaries and spread through the bloodstream in a condition known as military tuberculosis
Tubercles
a TB vaccine is available that is based on the Bacillus Calmette-Guerin (BCG) strain of _________ (bacteria) commonly found in cattle
M. bovis
what bacteria causes Pertussis?
Bordetella pertussis
B. pertussis secretes this toxin (AB toxin) and a tracheal cytotoxin that damages ciliated epithelial cells and results in the accumulation of mucus in the lungs
pertussis toxin
the bacteria multiply in the trachea and bronchi leading to mucus accumulation and causing _____ of cough - a rapid inrush of air following ________ resulting in a high pitch whooping sound
paroxysms
what vaccine may be used for pertussis
DPT vaccine
what is the causative agent of Legionellosis
Legionella pneumophila
the bacterium of this disease can infect free-living amoebae and inhabit moist environments. infections typically occur from human-made reservoirs such as air conditioning cooling towers, humidifiers, misting systems, and fountains. usually infects immunocompromised individuals. Most healthy individuals infected with this show what’s knows as Pontiac fever
legionellosis
the bacteria of Legionellosis infect ____ and live inside the macrophages
alveoli
what are the main symptoms of legionellosis
- high fever
- N/V
- muscle aches
this is a zoonotic disease. the primary reservoirs are domestic livestock such as cattle, sheep and goats; it is largely an occupational disease of farmers. it may be transmitted by ticks or through exposure to the urine, feces, or milk of an infected animal.
Q fever
humans are acutely sensitive to _______ the infective dose is estimated to just a few cells; this is the causative agent of Q fever
Coxiella burnetii
what are the symptoms of Q fever
- high fever
- headache
- coughing
- general malaise
*in some patients the condition may become chronic often leading to endocarditis which may be fatal
this is an infection of the middle ear. pathogens cause direct tissue damage and induces an inflammatory response that causes the formation and accumulation of pus in the middle ear resulting in moderate to severe bulging of the tympanic membrane and ear pain. sometimes, inflammation resulting from the infection leads to swelling of the Eustachian tubes, and may also lead to a fever, nausea, vomiting and diarrhea
acute otitis media
what is the most common causative agent of acute otitis media in neonates
streptococcus pneumoniae
what other causative agents may cause acute otitis media in neonates?
Escherichia coli, enterococcus spp. and group b streptococcus
what are the most common causative agents in older infants and children?
S. pneumoniae, haemophilus influenzae or moroxella catarrhalis
what are the causative agents of bacterial rhinosinusitis
S. pneumoniae, H influenzae and M catarrhalis.
bacterial infections of the _________ can be life-threatening because of the critical functions performed by the brain, spinal cord, and peripheral and cranial nerves
nervous system
where in the nervous system can infections occur?
nervous tissue and meninges
this is an inflammation of the brain or spinal cord meninges. bacteria may gain access to the CNS through the bloodstream after trauma. bacteria may spread from structures in the upper respiratory tract such as nasopharynx, middle ear, etc.
bacterial meningitis
what are the most common causes of bacterial meningitis?
- Neisseria meningitidis
- streptococcus peneumoniae
- haemophilus influenzae
can the bacteria that cause meningitis spread from person to person?
yes, they can spread by respiratory secretions. they colonize and cross through the mucous membranes of the oropharynx and nasopharynx and then enter the blood and go to the meninges
this specific type of bacterial meningitis is caused by Neisseria meningitidis (gram negative, coccus). patients suffer severe headache, fever, chills, stiff neck, and blue-black skin spots. non fatal cases can result in nerve damage resulting in hearing loss and brain damage.
meningococcal meningitis
Neisseria meningitidis was the most common cause of meningitis epidemics in human populations and have since become rare because of
meningococcal vaccines
what virulence factors are associated with Neisseria meningitis?
- endotoxin, lipooligosaccharide
- type IV pili for attachment to host tissues
- polysaccharide capsules that help the cells avoid phagocytosis
- secretion of IgA protease (which breaks down IgA antibodies)
- the invasion factors Opa, Opc and porin which facilitate transcellilar entry through the BBB
what is the causative agent of pneumococcal meningitis
Streptococcus pneumoniae (encapsulated, gram-positive bacterium)
true or false: S. pneumoniae can cross the BBB in susceptible individuals
true
what are the virulence facts produced by S. penumoniae?
- Pl-1 pilin for adherence to host cells
- virulence factor B (PavB) for attachment to host cells in the respiratory tract
- choline binding proteins (cpbA) that bind to epithelial cells
- the toxin pneumolysin that triggers an inflammatory response
what is the causative agent of haemophilus meningitis?
haemophilus influenzae tabe B (Hib) (gram negative, ecapsulated small rods)
this specific type of bacterial meningitis affects children in the first year or two of life. nerve disorder, fever, deafness and possible mental retardation
haemophilus meningitis
true or false: there is a vaccine for haemophilus influenzae
true
what are some common virulence factors of H. influenzae?
- endotoxin (LOS) which triggers inflammation
- haemophilus adhesion and penetration factor (Hap) aids in attachment and invasions
- has a polysaccharide capsule to avoid phagocytosis
- IgA1 protease and P2 protein that allow it to evade antibodies
what is the causative agent of neonatal meningitis?
Streptococcus agalactiae, group B streptococcus (GBS) (encapsulated gram positive)
where can S. agalactiae be found in humans?
can be found in the urogenital and gastrointestinal microbiota
these are bacteria that can also cause neonatal meningitis, but are not as common. they cause infection of the arachnoid mater and CSF after spreading through the circulation in blood or by spreading from an infection of the sinuses or nasopharynx
Listeria monocytogenes and Escherichia coli
