UK SMI notes – Ear Infections.

Type of specimen: Ear swab Middle ear fluid Scraping of material from the ear canal (for fungal infection) Expected organisms Otitis Externa Acute localised otitis externa Staphylococcus aureus Group A Streptococcus furuncle Erysipelas Acute diffuse otitis externa Pseudomonas aeruginosa S. aureus Anaerobes Treatment – topical cleaning of debris. Antibiotics are not useful. Chronic otitis externa Colonisation by Enterobacteriaceae Fungi Treatment…

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Staphylococcus lugdunensis

Bacteria Staph lugdunensis is a coagulase-negative Staphylococcus (CoNS) capable of causing aggressive diseases like Staph aureus. Staph lugdunensis tends to be more susceptible to antibiotics compared to other CoNS. Vancomycin tolerance – can be present, i.e. the ability of bacteria to survive in the presence of an antibiotic, even if MIC testing has deemed that…

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SMI: Investigation of whooping cough

Types of specimen Cough plates are not recommended. Selective media It contains blood or charcoal or both, along with selective antibiotic supplements – penicillin, cefalexin or meticillin.It should be able to suppress other nasopharyngeal flora. Meticillin is the least inhibitory, and cefalexin is the most. Cefalexin is the drug of choice for selective media in…

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SMI: Investigation of Throat-Related Specimens

Specimens Throat swab, posterior pharyngeal swab, nasopharyngeal swab, pharyngeal washings, pus aspirate, oropharyngeal swab, throat gargle. Why To investigate upper respiratory tract infection – Pharyngitis, Tonsillitis, Epiglottitis, and Laryngitis. Condition Target organisms Pharyngitis(sore throat) 1. Viral (commonest),2. Group A Streptococcus/ Streptococcus pyogenes,3. Group C/G Streptococcus – Streptococcus dysgalactiae subspecies equisimilis,4. Streptococcus anginosus group,5. Corynebacterium –…

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SMI (note): Investigation of swabs from the skin and superficial soft tissue infection

Specimen Advice for the users: Safety Processing Gram stain – usually not done unless deep-seated pus from a normally sterile site Plate selection CONDITION PLATES All clinical conditions Blood agarCLED/MacConkey agar Wound swab Selective anaerobic agar with metronidazole disc Pus Fastidious anaerobic, cooked meat broth;then Subculture to blood agar. Cellulitis in childrenHuman bite Chocolate agar…

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