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INFECTIOUS DISEASES F+CTOPICS • Background science • MCQs • Infectious disease history taking • OSCE scenarios • Sexual history taking • HIV explanation • Skin and soft tissue infections • STI testing and ethics • Infection and • HIV and HIV testing immunocompromised patients • TB • Infections and immunocompromised patientsBASICS • Bacteria can be classified in different ways: • Morphology • Gram staining • Aerobic v anaerobic • Extra-cellular v intra-cellular Gram staining: 1. Gram positive – Thick peptidoglycan cell wall 2. Gram negative – Thin peptidoglycan layer Antibiotics – SpectrumINFECTIOUS DISEASES – HISTORY T AKING • ID Specific areas: • PMH: • Travel history • HIV • Sexual history • Steroid use • Activities • Chemotherapy patients • Contact with animals Medications • Drug use – IVDU • Methotrexate • Food and drink? • Infectious contacts • Carbimazole • ClozapineT aking a complete sexual history • Is the patient sexually active? • Partners – Male/Female? Country of origin ? • Did you use drugs? Did the sex involve more than 1 partner? • Ask about other partners within the last 3 months • Type of sex – Oral/vaginal/anal • Given/received • When was the last sexual encounter? • Casual or regular partner? How long have they been partners? • Is the partner contactable? • Protected or unprotected sex? Any issues with the contraception? Was it used for the entire encounter? • Note: • Approaching the conversation – ‘ There are a few things that can cause the things you are describing, I’d like to ask you about your sexual history to assess whether these things are relevant…these are questions we ask everyone’ • Don’t assume! • MSM/WSWOSCES - SCENARIOS 1. HIV explanation 2. Confidentiality and STIs 3. Antibiotic prescribing 4. Immunocompromised patients and infectionsSKIN AND SOFT TISSUE INFECTIONS 1 1. Cellulitis 2. Necrotising fasciitis 3. Eczema herpeticumSKIN AND SOFT TISSUE INFECTIONS • Cellulitis – Infection of the dermis an subcutaneous layer of skin • Features: • Erythema • Tense Causative organisms: • Oedematus 1. Staphylococcus aureus 2. Streptoccous pyogenes • ‘Golden yellow crust’ – Staphylococcus aureus infection • Diagnosis • Clinical What if the patient got bitten by a dog? What would the management • Management: be? • Flucloxacillin – 1 line • Other antibiotics: Clarithromycin or Co – AmoxiclavSKIN AND SOFT TISSUE INFECTIONS • You’re an FY1 and the nurses have bleeped you because a patient has had a painful skin rash that has been worsening over the past few hours. The patient allows you to examine the skin but the rash is exquisitely tender. • As you examine the skin, the rash looks like this… • What are risk factors for this condition? • What are the common causative organisms for this condition? • Next steps?Necrotising Fasciitis Causative organisms- Can you think of the organisms? • Medical emergency! Gas gangrene – Side point ! • Features: • Pain out of proportion to clinical picture • Skin discolouration/blistering • Fever • Systemic upset • Oedema • Management: • Surgical debridement • Broad spectrum IV antibiotics • Bloods: FBC, U+Es, CRP, Coagulation screen, lactate, LFTs, blood cultures • ABGs – metabolic acidosis due to sepsis • CK- Muscle breakdown • Plain x- ray: Check for air spaces in the soft tissues on the x-ray • Risk factors: • Skin injury – bites, trauma , wounds • IVDU • Immunity – Immunosuppression, malignancy, diabetes • Extra pointsContinued… • You are a medical student in the GP practice. The GP asks you to speak to an individual who has come in with a skin rash.The rashEczema Herpeticum • Caused by HSV 1 • Features: • Painful punched out blisters • Unwell • May have fluid within blisters • Lymphadenopathy • Investigations • Clinical diagnosis • Management • IV acyclovirClinic time… • You’re a final year medical student on your GP placement. A 45 year old male has come into the practice after coming back from his backpacking trip in South Asia. He has been feeling unwell and has had a cough. He has been having weight loss, night sweats and fevers.TUBERCULOSIS 1. What features make you think of TB? 2. TB Investigations: 3. TB treatment and management 4. What other considerations do you have for management?TB Medications • RIPE! Rifampicin 6m Orange secretions Isoniazid 6m Peripheral neuropathy – Prevent with pyridoxine Pyrazinamide Hyperuricaemia 2m Ethambutol 2m Optic neuritis – Check visual acuity before and after treatmentHIV: Overview HIV infects CD4 T-cells and they are killed directly by the virus or killed by CD8 cells. Following infection, patients undergo seroconversion and develop symptoms around 3-12 weeks following an infection. Features of seroconversion: • Malaise • Muscle and joint pain • Sore throat • Mouth ulcers • LymphadenopathyHIV: Diagnosis p24 antigen and HIV antibody): HIV involves combination testing (HIV • The p24 antigen is present after around 1-4 weeks • HIV antibodies are present after around 4-6 weeks Testing for HIV: • If positive, repeat to confirm the diagnosis • If negative, repeat at 12 weeks to confirm negative status • If asymptomatic, test after 4 weeks of possible exposureHIV: Complications Depending on the CD4 count, different complications can arise: • CD4 200-500 /mm : 3 • Oral thrush • Shingles • Kaposi sarcoma 3 • CD4 100-200 /mm : • Pneumocystis jirovecii pneumonia • Cerebral toxoplasmosis • CD4 50-100 /mm : 3 • Oesophageal candidiasis • Aspergillosis • Cryptococcal meningitis • Primary CNS lymphomaHIV: Oral and Oesophageal Candidiasis Features: • Dysphagia • Odynophagia • White patches in the mouth Management: • Antifungals (e.g. fluconazole or itraconazole)HIV: Pneumocystis jirovecii pneumonia common opportunistic infection in AIDS.), PCP pneumonia is the most Features: • Dyspnoea • Dry cough • Fever • Chest signs may be absent • Exercise-induced desaturationHIV: Pneumocystis jirovecii pneumonia Investigations: • Chest x-ray: may show bilateral pulmonary infiltrates, may be normal • CT chest: may show bilateral ground glass opacities • Bronchoalveolar lavage: diagnostic test Management: • Co-trimoxazole – used both in acute infection and as prophylaxisHIV: Neurological Complications complication: HIV may present with features of a neurological • Headaches • Fevers • Night sweats • Weight loss • Cranial nerve abnormalities • Blurry vision • Slurred speechHIV: Neurological Complications Causes of focal neurological deficits may be: • Toxoplasmosis: • CT shows multiple ring-enhancing lesions, midline shift may be seen • Serology may be positive • Management: sulfadiazine and pyrimethamine • Primary CNS lymphoma: • CT shows single or multiple homogenous enhancing lesions • Management: steroids, surgery, chemotherapy +/- radiotherapyHIV: Neurological Complications Causes of generalised neurological disease may be: • Encephalitis – either due to cytomegalovirus or HIV • CT shows oedema • Cryptococcus: • Presents similar to meningitis but may have features of raised ICP • CSF shows high opening pressure, India ink positive • CT shows cerebral oedemaPractice Case 1 A 35-year-old man presents with a 3-week history of worsening shortness of breath and dry cough. He has no known past medical history. His temperature is 38.1°C, his heart rate is 105 bpm, his blood pressure is 128/85 mmHg, and his oxygen saturations are 85% on room air, but this increases to 95% when repeated. His chest is clear. What are the most appropriate next steps in his management?Practice Case 2 A 29-year-old man presents with a 3-day history of fever, right-sided weakness, and slurred speech. He has no known past medical history, however, has had recurrent episodes of severe infection requiring hospital admission. What are the most appropriate next steps in his management?OSCE SCENARIOS AND MCQS • Explaining HIV testing to a patient • STIs and confidentiality • ‘My partner has been given antibiotics – check their records for me!’ • Picking up on cues! • PMH – It’s very important • Medication history!! • PC: Diarrhoea – Asking about travel history! Fevers! • Lots to cover for MCQs! Online teaching materials are really good!