Understanding Ear Infections: Pathogenesis, Diagnosis, and Management

1. ENT BACTERIAL INFECTIONSDR K BABAMICROBIOLOGICAL PATHOLOGISTNHLS TSHWANE ACADEMIC DIVISIONUNIVERSITY OF PRETORIA

2. Introduction • Ear- external, middle and inner ear • Middle ear- nares, nasopharynx, auditory tube and the mastoid air space • Line with ciliated cells • Normal flora of external ear are pneumococci, propionibacterium, Staphylococcus, and Enterobacteriaceae

3. Otitis external • Acute • Localised or diffused • Localised- staphylococcus aureus and streptococcus pyogenes • Diffuse- swimmer’s ear • Severe hemorrhagic external otitis media • Pseudomonas aeruginosa

4. Otitis external • Chronic- irritation of drainage from middle ear • Malignant – necrotizing infection • Common in diabetes • Pseudomonas aeruginosa • Mycoplasma pneumoniae- painful infection of eardrum

5. Otitis media • Acute • Common in children • Pnemococci, Haemophilus influenzae, Streptococcus pyogenes, • Others are S. aureus, moraxella, Enterobacteriaceae, anaerobes, Chlamydia trachomatis, and mycoplasma pneumoniae

6. Otitis media • Chronic • Mainly anaerobes- Peptostreptococcus, Bacteroides, Prevotella, Fusobacterium • Complication- mastoiditis • Treatment with Amoxicillin/ Amoxi-clavulanate

7. Pathogenesis • Local trauma • Foreign bodies • Excessive moisture • Infection from middle ear • All this can lead to otitis external

8. Pathogenesis • Anatomic abnormalities of auditory tube • Negative pressure in the middle ear from inflamed auditory tube following viral infection • Pathogenic bacteria then enters from the nasopharynx

9. Laboratory diagnosis • Needle aspirates • Mastoid swabs • Mastoid tissue • Microscopy, culture and sensitivity

10. Sinusitis • Sinuses are air filled cavities within the head • Normally sterile • Acute sinusitis- cold / influenza infection • Purulent nasal and postnasal discharge • Feeling of pressure over the sinus area • Cough • Sometimes fever

11. Sinusitis • Chronic with bacterial colonization • Surgery/drainage • Treatment with Amoxicillin/ Amoxi-clavulanate • Complications- extension to the orbit, skull, meninges, brain

12. Pathogenesis • Bacterial complication of common cold • Maxillary infection from dental source • Inadequate drainage • Mucociliary clearance and mucosal damage

13. Etiolgy • Haemophilus influenzae • Streptococcus pneumoniae • Streptococcus pyogenes • Moraxella • Anaerobes

14. Laboratory diagnosis • Puncture and aspiration • Sinus drainage is unacceptable because of contamination • Microscopy and culture

15. Case 2 • A 6 month old baby presents with flu like symptoms. Greyish adherent membrane was found on the tonsil. • What is the clinical diagnosis • What sample would you send to the laboratory to confirm your diagnosis • What are the characteristics of the causative organism • How would you manage the patient

16. C. diphtheriae • Transmission • droplet infection; hand to mouth • Laboratory Diagnosis • Nasopharyngeal secretions or swabs • Throat /nasal swabs • Loffler’s; Hoyle’s; Tellurite containing blood agar • Black and shiny colony • Elek’s for toxin production • Nucleic acid amplification with sequencing

17. Pathogenesis • Diphtheria toxin • Bacteriophage carrying the tox gene • Classic A-B toxin • A active subunit and B binding subunit • Block protein synthesis • Inactivate elongation factor 2 (EF-2) required for polypeptide elongation

18. Diseases • Respiratory: tonsilitis, pharyngitis (fever, sore throat, grey pseudomembrane on the tonsils) • Cutaneous: ulcerating skin lesion with grey membrane • Complications: Severe and potentially fatal; nerve weakness/paralysis; myocarditis/cardiac failure; airway obstruction

19. Management • Antitoxin • Penicillin/Erythromycin • Vaccine is usually administered together with pertusis and tetanus toxoids as DPT

20. Thanks