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  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.

Acute follicular tonsillitis

Acute peritonsillar abscess (quinsy) with trismus

White strawberry tongue with circumoral pallor

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.

Corynebacterium diphtheriae

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

Pneumococcal lobar pneumonia

Psittacosis pneumonitis

Post-aspiration lung abscess: fluid level

Aspiration pneumonia  Inhalation of vomit or foreign body  S.pneumo. + anaerobes (Bacteroides melaninogenicus, Fusobacterium spp.  Lung abscess (O 2 + anO 2 )  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).  O 2 &an O % CO 2  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