respiratory tract infections Flashcards
what are the the common normal microbiota of the RT?
(common >50% of people)
- bacteroides spp.
- Candida albicans
- oral streptococi
- haemophilus influenza
what are the normal microbiota of the RT found in the latent state in in tissues?
- herpes simplex virus type I
- epstein Barr Virus
- cytomegalovirus
- mycobacterium
what are the normal microbiota of the RT that are only occasionally found?
(occasional <10% in normal people)
- streptococcus pypgenes
- streptococcus pneumoniae
- neisseria meningiditis
what are the main respiratory tract host defences?
- saliva
- mucus
- cilia
- nasal secretions
- antimicrobial peptides
- alveolar macrophages
what are examples of the normal microbiota found in the nasal passages and sinuses?
- fermicutes
- actin bacteria
- staphylococcus epidermis
- haemophilus spp
- staphylococcus aureus
what are the normal microbiota found in the oral pharynx?
- prevotella
- fusobacterium
- candida spp
- haemophilus
- neisseria
- streptococcus
what are the normal microbiota found in the Lower respiratory tract?
- pseudomonas
- streptococcus
- prevotella
common cold:
actual name?
tranmission?
causative agents?
seasonal?
name = acute coryza
transmission = aerosol, virus- contaminated hands
causative agents = 40% rhinovirus (>100 serotypes)
30% coronaviruses (>3 serotypes)
coxsackie virus A
Echovirus
Parainfluenza
seasonal = early autumn and mid/late spring
why are colds less common in summer?
because uV light tends to kill the pathogens.
clinical features of common cold?
- tiredness
- slight pyrexia
- malaise
- sore nose & pharynx
- profuse, watery nasal discharge
- sneezing in early stages
- secondary bacterial infection occurs in minority
describe the pathogenesis of the common cold?
what are the viral and bacterial causative agents for acute pharyngitis and tonsillitis?
virus:
- Epstein-Barr virus
- cytomegalovirus
- HSV1
- rhinovirus
- coronavirus
- adenovirus
bacteria:
- streptococcus pyogenes
- haemophilus influenza
describe the cytomegalovirus (CMV)
- transmission in body secretions and organ transplants
- usually asymptomatic
- virus can reactivate and cause disease when cell-mediated immunity is compromised
- diagnose secondary infection using IgM in the blood
- diagnose CMV pneumonitis using CMV Ag in BAL
- treatment with ganciclovir, foscarnet, cidofovir
describe Epstein- Barr virus?
- replicated specifically in B lymphocytes (CD21)
- causes glandular fever
- transmitted by saliva and aerosol
- usually occurs in 2 peaks:
1-6 years old
14-20 years old
incubation period: 4-8 weeks
illness= 4-14 days
clinical features of glandular fever?
- fever
- headache
- malaise
- sore throat
- anorexia
- palatal petechiae
- cervical lyphadenopathy
- mild hepatitis
- swollen tonsils
- white exudate
- petechiae on the soft palate
tonsilitis:
causes
transmission?
treatment?
caused by= streptococcus pyrogenes
tranmission= by airborne droplets and contact
- confection occurs mainly in children
- 15-20% become asymptomatic carriers
- treat with penicillin
what does strep. progenies havee an increasing resistance to in tonsillitis?
erythromycin and tetracycline
clinical features of tonsillitis?
- fever
- pain in throat
- enlargement of tonsils
- tonsils lymphadenopathy
streptococcus pyogenes
- group A streptococcus
- gram positive cocci in chains
- cultured in blood agar
- haemolytic activity ue to exotoxin streptomycin
- susceptible to treatment with penicillin
complications of streptococcus pyogenes ?
parotitis?
- caused by mumps virus
- paramyxovirus family
- transmission by droplet spread and fomites
- communicable in 2 days before disease onset
- diagnosis is based on clinical features - IgM serology can be performed in doubtful cases from saliva, CSF or urine.
who does parotitis normally effect?
clinical features?
- primarily effects school aged children and young adults
- clinical features:
- fever
- malaise
- headache
- anorexia
- trismus
- severe pain and swelling of parotid glands
parotits:
treatment?
prevention?
complications?
treatment:
- mouth care
- nutritional
- analgesia
prevention:
- active immunisation
- measles mumps rubella vaccine (MMR)
complications:
- CNS involvement
- epididymo orchitis
acute epiglottis?
- caused by haemophilus influenza
- most often seen in young children
- 88% reduction in England and Wales since advent of Hib vaccine in 1992
clinical features of acute epiglottis?
- high fever
- massive oedema of the epiglottis
- severe airflow obstruction resulting on breathing difficulties
- bacteraemia
haemophilus influenza