Infections Of The Skin and respiratory tract Flashcards
What are the features of cellulitis?
Redness
Swelling exudate
What is the most common bacterial cause of cellulitis?
S. Aureus.
What is the presumptive choice of antibiotic treatment of cellulitis?
Flucloxacillin
How is erysipelas different to cellulitis?
Redness is usually on face or legs in areas of prior ulceration, abrasion or lymphatic damage. Lesion has a distinct raised edge.
What is the most common bacterial cause of erysipelas?
S.pyogenes.
What is the antibiotic of choice for erysipelas?
Penicillin
What is impetigo?
Painless confluent vesicles that progress to dried out yellow crusts.
What is the most common bacterial cause of impetigo?
S. Pyogenes.
What abx is used for impetigo?
Oral or Im penicillin.
What causes shingles?
A reactivation or varicella zoster virus.
What is the treatment for shingles?
Disease is usually self limiting.
Symptomatic relief is difficult as pain is neural in origin.
What is gas gangrene?
An infection that involves the muscles and adjacent soft tissues.
What causes gas gangrene?
C. Perfringens.
What is the management for gas gangrene?
Surgical resection of necrotic tissues
IV penicillin
Oxygen
What is necrotizing fasciitis?
An infection of the subcutaneous soft tissues involving superficial and deep fascia.
What is the most common cause of necrotizing fasciitis?
S. Pyogenes. Infection spreads along soft tissue planes.overlying skin breaks down.
What is the treatment for necrotizing fasciitis?
A combination of ampicillin, gentamicin and metronidazole given IV. Surgical exposure of affected fascial planes.
What are the most common causes of pharyngitis?
Respiratory viruses: rhinovirus, coronavirus, adenovirus, influenza, EBV
What is the most common cause of bacterial pharyngitis?
S.pyogenes.
Rarer: Neisseria gonorrhoea, M.Pneumoniae, C. Diptheriae.
What antibiotic is commonly used to treat streptococcal pharyngitis?
What is the aim of treatment?
Oral penicillin or erythromycin.
Aim of treatment is to reduce risk of complications eg rheumatic fever, scarlet fever.
Which viruses commonly cause the flu?
Influenza groups A-C
What are the main symptoms of influenza infection?
Fever, lethargy, myalgia, common cold like symptoms.
What kind of virus is influenza?
An RNA virus
Which major surface antigens are found on influenza?
Haemagluttinin and neuraminidase.
What is antigenic drift?
Minor changes in antigenic makeup between epidemics. This means that a vaccine can be developed for the virus, but needs to be remade each year.
What treatments exist for influenza?
Mainly symptomatic relief
Neuraminidase inhibitor- oseltamivir, may reduce duration of symptoms.
What is otitis media?
An acute inflammation of the middle ear. More common in younger children as their eustachian tubes are shorter and more horizontal.
Which bacteria commonly cause otitis media?
S.pneumoniae or H.influenzae.
What are the symptoms and signs of otitis media?
Fever and local pain. Tense red tympanic membrane
What are the complications of otitis media?
Ear drum rupture
Meningitis
Mastoiditis
What is the abx of choice for otitis media?
Erythromycin or ampicillin.
What is otitis externa?
Inflammation of the external auditory meatus.
What is the most common cause of otitis externa?
Aspergillus niger.
What is the treatment for otitis externa?
Topical agents such as aluminium acetate.
What is acute sinusitis?
Infection of axillary, frontal, ethmoid or sphenoidal sinuses with bacteria from nasopharynx following impaired drainage in upper respiratory tract infection.
What are the most common bacterial causes of acute sinusitis?
S.pneumoniae and H.influenzae.
What is the treatment for acute sinusitis
Decongestants to improve drainage.
What is laryngitis?
Caused by one of the respiratory viruses and is a self limiting condition of hoarseness and loss of voice. No specific treatment required.
What are the symptoms of acute bronchitis?
Cough, production of creamy white sputum.
No CXR findings.
What is acute bronchitis caused by
M. Pneumoniae
What is tracheobronchitis?
Acute bouts of coughing which is not accompanied by significant sputum production. Caused by influenza virus.
What is an acute exacerbation of chronic bronchitis?
A chronic productive cough changes to become productive of larger quantities of newly purulent sputum.
What commonly causes an acute exacerbation of chronic bronchitis?
S. Pneumoniae or H influenzae
What is the treatment for bronchitis?
Oral ampicillin or erythromycin
What are the symptoms of community acquired pneumonia?
Fever
Cough- may or may not have sputum
CXR signs- areas of consolidation, fluid in air spaces, effusion or cavity.
Impairment of respiratory function
What are the causative organisms of CAP?
How do their presentations differ?
Strep Pneumoniae- sudden onset pleuritic pain, fever, rusty sputum. Cold sores.
Klebsiella pneumoniae- thick, viscous red sputum.
S. Aureus- pneumonia following influenza
M.pneumoniae- non productive cough and pharyngitis in young adult
Legionella- non productive cough, confusion and diarhhoea.
What are the 4 stages of disease in pneumonia?
Congestion
Red hepatisation
grey hepatisation
Resolution
What are the 4 types of pneumonia?
Lobar- confined to one lobe- commonly S. Pneumoniae
Bronchopneumonia- patchy consolidation around larger airways. Commonly S.pneumoniae, H. Influenzae, S. Aureus.
Also:interstitial pneumonia, aspiration pneumonia
What is the presumptive therapy for CAP?
Amoxicillin
Clarithromycin
Or doxycycline
How is severity of pneumonia assessed?
CURB 65 score- confusion Urea> 7mmol RR>30 BP-<90/60 >65 years.
What is the definition of pneumonia?
An infection of the lower airways which is accompanied by X ray changes.
Which organisms commonly cause hospital acquired pneumonia?
P. Aeruginosa
S. Aureus.
Enterobacteriacae
How does pulmonary tuberculosis commonly present?
Acute bronchopneumonia, pulmonary cavitation, miliary TB
Often- weight loss, night sweats, fever, haemoptysis.
How is TB transmitted?
Air borne in droplets.
What virulence factors does mycoplasma tuberculosis have?
Thick, lipid containing cell wall, rendering it resistant to phagocytosis. This causes them to become walled off by fibrosis and form a granuloma with central caseating necrosis.
What characteristic X Ray sign can be seen in TB?
Gohns focus
Which special stain is used to identify TB?
Zhiel Nielsen Stain (ZN stain)
What is the treatment for TB?
Combination of 4 antibiotics to prevent resistance- RIPE Rifampicin Isoniazid Pyrazinamide Ethambutol
What is empyema?
An accumulation of purulent fluid in the pleural space. Caused by direct extension from underlying pneumonia, infection resulting from penetrating thoracic trauma or haematogenous spread.
What organisms can cause empyema?
S.aureus, enterobacteriacae, streptococci and obligate anaerobes.
How is empyema diagnosed?
May be evident on CXR , also there will be dullness to percussion.
What abx is used in empyema?
Depends on results of gram stain but should include an agent active against obligate anaerobes eg metronidazole
