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Respiratory Tract Infections. Causative Organisms. Viral most common Bacterial Fungal less common Two sites of RT: Upper RT (throat, pharynx, mid.ear, sinuses) Lower RT (trachea, bronchi, lungs). Upper RTI. Throat & pharynx: Sore throat : 2/3 viral, 1/3 bacterial
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Causative Organisms • Viral most common • Bacterial • Fungal less common Two sites of RT: • Upper RT (throat, pharynx, mid.ear, sinuses) • Lower RT (trachea, bronchi, lungs)
Upper RTI • Throat & pharynx: • Sore throat : 2/3 viral, 1/3 bacterial • Bacterial causes: • Streptococcal sore throat: • 1- acute follicular tonsillitis • ß-haemolytic S.group A common • less common group C,G
Upper RTI (Continue) • 2- scarlet fever: Step.A • Erythematous rash + sore throat • Source : carrier • Rarely complicated by pritonsillarr abscess, quinsy ,otitis media,or sinusitis.
Streptococcus group A • Complications: early , late • Early complications: • quinsy, sinusitis, otitis media • Late complications: • rheumatic fever • acute glumerulonephritis
Rheumatic fever • Revision • 2-5 wks after Strept. Throat infection • Clinical features • Pathology • Prognosis • Diagnosis : M types 5,18,24) • Serology (ASO titre= 200 or more)
Treatment of rheumatic fever • Penicillin + long term prophylaxis
Acute glomerulonephritis • Immunological complications of throat & skin infection by Strep. Group A. • 1-3 wks later • Few serotypes implicated (12, 44). • Clinical features / pathogenesis/ prognosis • Diagnosis: throat &skin swabs+ C3. • No prophylaxis needed
Diphtheria (revision) • Toxins: neurotoxin ( cranial) • cardiotoxin (heart block) • Diagnosis • Management & treatment • Prevention
Pharyngotonsillar diptheria: note adherent membrane with curled edge.
Gel-diffusion plate to demonstrate toxigenicity of diphtheria bacilli
Vincent’s angina • Ulcerative tonsilitis extension from gingivostomatitis • Organisms: Borrelia vencenti & Fusobacterium. • Treatment : penicillin or metronidazole
Diagnosis of throat & pharyngeal infections • History / clinical examination • Specimens • Microscopy :Gram stain • Culture: blood agar , crystal violet B/A(for Str. A), Loffler’s serum or Tellurite medium( for C.diphtheriae)..
Middle ear & sinus infections • Often secondary to bacterial or viral infection of RT. • Acute otitis media: extension through Eustachian tube. • Bacteria: H.influenzae • S. pyogenes • S.pneumoniae
Sinusitis • Frontal & maxillary • Bacteria : as otitis media. • Chronic sinusitis: S.aureus, coliforms & bacteriodes also involved. • Diagnosis: • Myringotomy (otitis media) • Drainage of pus (sinusitis) • Treatment: sens. test. ( systemic and or local)
LRTI • Laryngitis: associated with or follow viral • Clinically: croup (acute tracheobronchitis) • More common in children • Caused by H.influenzae
Acute epiglotitis • Children up to 5 yrs. • Rapid progression to obstruction & death. • H.influenzae type b. • Management: emergency tracheostomy • I.V. ceftriaxone
Bronchitis • Acute bronchitis: follow viral / self limiting • Chronic bronchitis: c.resp. diseases. • Exacerbation by cold, smoking,…etc. • Bacteria: HI (non capsulated), S. pneumo., Moraxcella, Mycoplasma Pneumoniae.
Treatment of bronchitis • Sick pts. & chronic cases • Short term: augmentin, erythromycin , azithromycin , clarithromycin. • Long term prophylaxis: controversial • Vaccines: influenza (A,B) • Pneumococcal poly.sacch.
Cystic fibrosis • Autosomal recessive, abnormal viscid mucous blocks tubular lung structures & other organs • S.aureus, HI (early) • Psudomonas aerugenosa (late) • Treatment: ceftazidime ,ciprofloxacin • Long term
Pertussis • Whooping cough • B. pretussis • Stages • Complications • Diagnosis: pernasal swab or cough plate • Culture: Bordet-Genguo/ Charcoal med. • Id., serology • Treatment / prevention
Infections of the lungs • Pneumonia: • Clinically, lung consolidation • Types: • lobar (segmental) S.pneumoniae • bronchopneumonia -S. pneumo.+ HI • primary atypical - viruses , Mycoplasma pneumo.,Chlamydia & Coxiella.
Bacterial causes • 1- S.pneumoniae ( exogenous ,endogenous) • 2- HI • 3-S.aureus • 4-coliforms (hospital, Ventilates pts.) • 5- Mycoplasma, Coxiella, Chlamydia • 6- MTB (chronic) 7- Legionella
Aspiration pneumonia • Inhalation of vomit or foreign body • S.pneumo. + anaerobes (Bacteroides melaninogenicus, Fusobacterium spp. • Lung abscess (O2 + anO2) • Empyema: pus in pleural space. Aspiration + antibiotic needed.
Diagnosis of chest infections • History , examination • Isolation of bacteria from: sputum, aspirate,…and blood culture (pneumonia) • Microscopy: pus cells, squamous cells, bacteria. • Z-N if indicated
Diagnosis of chest infections (Continue) • Homogenize sputum before culture • Media: BA, Chocolate , /MacConkey agar (LJ if indicated). • O2 &an O2 +5-10 % CO2 • Assess culture: +++pus cells & heavy pure growth of bacteria
Serology • Not done routinely • If bacteria difficult to grow E.g. Mycoplasma pneumo., Coxiella, Chlamydia, Legionella • IF , CFT