Respiratory tract infections Flashcards
Respiratory Tract infection may be localised at any level of the respiratory tract, including
Respiratory Tract infection may be localised at any level of the respiratory tract, including
Ears, eyes, (continuous with resp tract and lined with resp. epithelium) nose throat trachea and the lungs themselves.
When bacteria, viruses or fungi target the lung then the consequences are more serious
Gas exchange is ………… and microorganisms can enter the ………… stream and cause ………….
When bacteria, viruses or fungi target the lung then the consequences are more serious
Gas exchange is impeded and microorganisms can enter the blood stream and cause septicaemia.
Respiratory system defence
Upper respiratory Upper respiratory tract – lined with mucus containing I... L.......... L............ Ci.......... ep.......... cells Hairs in the nose ................ air Ear wax acts as ........... Conjunctiva bathed with ............... containing ..............
Antibacterial …………….. secreted.
Resident flora ………. receptor sites
Upper respiratory tract – lined with mucus containing IgA Lysozyme Lactoferrin Ciliated epithelial cells Hairs in the nose filter air Ear wax acts as barrier Conjunctiva bathed with tears containing lysozyme. Antibacterial peptides secreted. Resident flora occupy receptor sites.
Respiratory system defence mechanisms – lower respiratory tract
Two fold:
mechanisms to prevent microbes ………… the lung and those designed to eliminate any microbes that do reach the lung.
Alveolar macrophages in the lung
De…………….
Inflammation allows bacteria to breach barriers that separate ………… and ………. cells and enter the bloodstream.
Respiratory system defence mechanisms – lower respiratory tract
Two fold:
mechanisms to prevent microbes entering the lung and those designed to eliminate any microbes that do reach the lung.
Alveolar macrophages in the lung
Defensins.
Inflammation allows bacteria to breach barriers that separate lung and blood cells and enter the bloodstream.
Bacterial Defence Mechanisms
Microbes evade the URT mechanisms by being carried in s……. p……….. ae………… or taking advantage of natural breaches of the cell defence
Influenza often precedes bacterial ………….., because temporarily destroys …………. cells
Smoking depresses ……….. cell function.
Alveolar macrophages provide first line of defence followed by …………, natural killer cells and Tc cells.
Bacterial Defence Mechanisms
Microbes evade the URT mechanisms by being carried in small particle aerosols or taking advantage of natural breaches of the cell defence
Influenza often precedes bacterial pneumonia, because temporarily destroys ciliated cells
Smoking depresses ciliated cell function.
Alveolar macrophages provide first line of defence followed by neutrophils, natural killer cells and Tc cells.
Host predisposition
Some pathogens successfully infect normal healthy respiratory tract
‘the professionals’
Others ‘secondary invaders’ only cause disease in hosts with impaired defences
Cystic ……………..
Chronic ………………
Ob………….. airway disease (COAD)
The i……………………
Those with depressed resistance, e…….., alco………, renal and he……….. disease.
Host predisposition
Some pathogens successfully infect normal healthy respiratory tract
‘the professionals’
Others ‘secondary invaders’ only cause disease in hosts with impaired defences
Cystic fibrosis
Chronic bronchitis
Obstructive airway disease (COAD)
The immunocompromised
Those with depressed resistance, elderly, alcoholics, renal and hepatic disease.
upper respiratory tract infections
The common cold.
- Caused by many types of virus, commonest invader of the ……………….
- ……….viruses and coronaviruses cause more than 50%.
Pharyngitis and tonsillitis.
- 70% are caused by viruses
- Rhinoviruses, ………… viruses, ……….viruses, i……………. and p……………. , E……
Sore throat as result of infection of overlying mucosa and inflammatory and immune responses in l……………. tissue.
Most do not need laboratory diagnosis, except E…….
- Diagnosed by antibody profile and by ………… cell count and differential.
upper respiratory tract infectioon
The common cold.
- Caused by many types of virus, commonest invader of the nasopharynx.
- Rhinoviruses and coronaviruses cause more than 50%.
Pharyngitis and tonsillitis.
- 70% are caused by viruses
- Rhinoviruses, coronaviruses, adenoviruses, influenza and parainfluenza, EBV.
Sore throat as result of infection of overlying mucosa and inflammatory and immune responses in lymphoid tissue.
Most do not need laboratory diagnosis, except EBV.
- Diagnosed by antibody profile and by white cell count and differential.
tions
Upper Respiratory tract infections
Bacterial causes include
- Group ….. st……..
- Haemo……….. infl………………
- Bor………. vin…….. together with other fusi……….. bacteria
- Ne…………… gon…………..
- Co……………. dip………….
All attach to mucosal surfaces and may invade local tissues.
Laboratory diagnosis often necessary
- Throat ……….. cultured onto
- Blood ………….. aerobically and anaerobically
- -Chocolate agar for …. and …….
Upper Respiratory tract infections
Bacterial causes include
- Group A strep
- Haemophilus influenzae
- Borrelia vincenti together with other fusiform bacteria
- Neisseria gonorrhoea
- Corynebacterium diphtheriae.
All attach to mucosal surfaces and may invade local tissues.
Laboratory diagnosis often necessary
- Throat swab cultured onto
- Blood agar aerobically and anaerobically
- -Chocolate agar for HI and NG.
Ear Infections, otitis externa, otitis media.
Otitis media common in young children because eustachian tube opened more widely.
Many infections are viral or bacteria originating in the nasopharynx
- Strep pn……………..
- Ha……………….. influenzae
- Group … s……….
- St. ……………..
Children often develop glue ear after infection.
Otitis externa can be caused by
- St. …………….
- Candida ………………….
- P……………
All favour warm moist environment.
Ear Infections, otitis externa, otitis media.
Otitis media common in young children because eustachian tube opened more widely.
Many infections are viral or bacteria originating in the nasopharynx
- Strep pneumoniae
- Haemophilus influenzae
- Group A strep
- St. aureus.
Children often develop glue ear after infection.
Otitis externa can be caused by
- St. aureus
- Candida albicans
- Proteus.
All favour warm moist environment.
Ear Infections, otitis externa, otitis media.
Laboratory diagnosis.
- …… swab cultured;
- Blood agar, aerobic and - anaerobic
- Ch………….
- Ma……………..
- Sab plate for the y………….
Otitis media will need oral a………………
Otitis externa often treated with e………drops containing antibiotic such as ……………
Ear Infections, otitis externa, otitis media.
Laboratory diagnosis.
- Ear swab cultured;
- Blood agar, aerobic and - anaerobic
- Chocolate
- MacConkey
- Sab plate for the yeast.
Otitis media will need oral antibiotics
Otitis externa often treated with ear drops containing antibiotic such as polymixin.
Secondary and confirmatory tests for bacterial isolates
Group A streptococcus
- Observation of ……….. haemolysis followed by
Strep. Grouping.
Strep pneumoniae
- Characteristic c…………. on blood and chocolate agar, sensitivity to o…………. disc.
Haemophilus influenzae
- Growth on nutrient agar around XV, ……… and ………. discs.
St.aureus
- Confirm by co……….. and ……. test.
All of the above will need to have antibiotic susceptibility tests performed on the isolates.
Secondary and confirmatory tests for bacterial isolates
Group A streptococcus
- Observation of beta haemolysis followed by
Strep. Grouping.
Strep pneumoniae
- Characteristic colonies on blood and chocolate agar, sensitivity to optochin disc.
Haemophilus influenzae
- Growth on nutrient agar around XV, X and V discs.
St.aureus
- Confirm by coagulase and DNA test.
All of the above will need to have antibiotic susceptibility tests performed on the isolates.
Lower Respiratory tract infections
May be classified into acute and chronic infections.
Acute:
- Bro………, exacerbations of chronic bronchitis, bronc……… , pne………. Infl……….., which may progress to bron…… or pneumonia. Wh……….. cough.
Chronic:
- T.., asper………, lung abs…….. and emp………, infections in cystic fi…………. patients.
Lower Respiratory tract infections
May be classified into acute and chronic infections.
Acute:
- Bronchitis, exacerbations of chronic bronchitis, bronchiolitis , pneumonia. Influenza, which may progress to bronchitis or pneumonia. Whooping cough.
Chronic:
- mTB, aspergillosis, lung abscesses and empyema, infections in cystic fibrosis patients.
Acute LRTI- Whooping cough
Whooping cough.
Caused by Gram …………… co……., Bordetella pe…………
Spread by droplet infection person to person
- Attach and multiply in cil………. respiratory mu………..
- Incubation of 1-3 weeks
- Dry cough that becomes paroxysmal- short coughs producing mucus followed by w………..
Damage by 3 exotoxins
- Pe………… toxin
- Ade…………. cyclase toxin and tracheal cytotoxin
- The bacterial en………….
Complications can affect CNS and also cause secondary pn……….. Treated with eryth………….
Disease now largely prevented by vac…………
Diagnosed in laboratory
- from pernasal swab transported in charcoal medium
Culture on Bordet-Gengou plates (blood charcoal).
- Characteristic ……….. colonies, confirmed with reaction with specific anti…………
Whooping cough.
Caused by Gram negative cocci, Bordetella pertussis.
Spread by droplet infection person to person
- Attach and multiply in ciliated respiratory mucosa.
- Incubation of 1-3 weeks
- Dry cough that becomes paroxysmal- short coughs producing mucus followed by whoop.
Damage by 3 exotoxins
- Pertussis toxin
- Adenylate cyclase toxin and tracheal cytotoxin
- The bacterial endotoxin.
Complications can affect CNS and also cause secondary pneumonia. Treated with erythromycin.
Disease now largely prevented by vaccination.
Diagnosed in laboratory
- from pernasal swab transported in charcoal medium
Culture on Bordet-Gengou plates (blood charcoal).
- Characteristic pearl colonies, confirmed with reaction with specific antisera.
Bronchiolitis
Childhood disease, mainly in under two year olds.
- Affects the bron…………. and restricts air to …………
- Ne………… of the epit……….. cells lining the bron…………
- May progress to pneumonia.
Main pathogen is Respiratory Syncytial Virus (RSV)
- 75% of cases and remaining cases generally of viral origin.
Spread by droplets and has seasonal peak in the winter months.
- Virus invades the LRT by ……… surface spread.
Bronchiolitis
Childhood disease, mainly in under two year olds.
- Affects the bronchioles and restricts air to alveoli.
- Necrosis of the epithelial cells lining the bronchioles.
- May progress to pneumonia.
Main pathogen is Respiratory Syncytial Virus (RSV)
- 75% of cases and remaining cases generally of viral origin.
Spread by droplets and has seasonal peak in the winter months.
- Virus invades the LRT by direct surface spread.
Bronchiolitis – diagnosis of RSV.
Diagnosed from endoph……………. secretions.
About 1% of infants will require hospitalisation.
- Cough, rapid respiratory rate and cyanosis.
Severity of symptoms thought to be related to ………… antibodies in infant reacting with virus antigens, with perhaps liberation of …………..
Disease restricted to ……. in older children and adults
Giving cold like ………………..
Can be diagnosed by immuno……………. of cells from the na…………………. washings or by EIA. Often solid phase E…….
Treat with ri…………..
Diagnosed from endopharyngeal secretions.
About 1% of infants will require hospitalisation.
- Cough, rapid respiratory rate and cyanosis.
Severity of symptoms thought to be related to maternal antibodies in infant reacting with virus antigens, with perhaps liberation of histamine.
Disease restricted to URT in older children and adults
Giving cold like symptoms
Can be diagnosed by immunofluorescence of cells from the nasopharyngeal washings or by EIA. Often solid phase EIA.
Treat with ribavirin.
