Infectious diseases Flashcards

Question

HIV Infection Transmission Stages of infection Presentation Investigations Other tests

Answer 1

**HIV** **Infection process** Retrovirus Envelope glycoprotein [gp120] binds to CD4 and CCR5 Reverse transcriptase makes viral DNA Incorporated into viral genome Viral proteins/virions replicate T Cell death **Transmission** Sexual contact Blood/organ transfusion IV drugs Pregnancy/childbirth/breast feeding Occupational **Stages of infection** _Seroconversion_ 4-8 weeks after infection Fever, night sweats, lymphadenopathy, sore throat, rash, oral ulcers, myalgia, headache, encephalitis, diarrhoea _Early/asymptomatic_ 18 months to 15 years Persistent lymphadenopathy + minor symptoms _AIDS_ Secondary diseases reflecting severe immunodeficiency CD4 cell count \<200/mm3 **Presentation** Opportunistic infections due to immunocompromisation: Bacterial: Mycobateria, staphylococcus, salmonella, encapsulated organisms Viral: HHV8/Kaposi Sarcoma, VZV- recurrent shingles, HSV, CMV, HPV- warts, EBV- oral hairy leukoplakia, papovavirus- leukoencephalopathy Fungal - Cryptococcus, invasive aspergillus, pneumocystis pneumonia, candida Protozoa- toxoplasma,cryptosporidia, microsporidia [Ring lesions in CT brain- toxoplasma gondii Pneumonia- causes CXR infiltrates] **Investigations** ELISA- Western blot Serum HIV rapid test Serum HIV DNA PCR [infants] CD4 count- monitor immune status + staging Serum viral load [HIV RNA]- millions of copies FBC, U+E, LFT **Other tests** Drug resistance Serum hep B and C serology Syphilis screening TB - tuberculin skin test

Answer 2

Hairy Leukoplakia Definition Irregular white painless plaques on lateral tongue- cannot be scraped off Aetiology Caused by EBV Happens in HIV patients or people immunosuppressed because of organ transplants

Answer 3

Candidiasis Definition Infection with candida species Thrush Epidemiology V common Oral candiasis- 40-70% of adults and children **Aetiology** Dimorphic fungus infection Candida albicans - commonly causes thrush **Conditions/types of candida infection** Oral candidiasis/oesophageal trush Vulvovaginitis/balanitis Diaper rash Infective endocarditis Disseminated candiasis [in blood stream, multiple organs affected] **Risk factors** Oral candidiasis/oesophageal thrush-\> immunocompromised/steroid inhalers Vulvovaginitis/balanitis-\> diabetes, antibiotic use Infective endocarditis-\> IV drug use Disseminated candiasis-\> immunocompromise/neutropenia **Symptoms** Oral candidiasis/oesophageal thrush- dysphagia Vulvovaginitis/balanitis- itching, soreness, redness, thick cottage cheese discharfe Diaper rash Infective endocarditis Disseminated candiasis- fever, hypotension, leucocytosis **Investigations** Clinical diagnosis Basic obsevations + examinations Swabs useless- b/c commensal in a lot of people anyway _Other investigations to exclude differentials or risk factors_ Urinalysis- UTI Random/fasting blood glucose + glucose tolerance test- diabetes HIV antibodies Vaginal pH- STIs **Management** Antifungal [-azole] Microconazole oral gel Nystatin suspension For vulvovaginal- intravaginal cream/pessary or oral antifungal For oesophageal/systemic- amphotericin B

Answer 4

**Kaposi's sarcoma** - may present as a pink or violaceous [purple] patch on the skin or in the mouth - AIDS defining condition - Caused by HHV8 **Squamous cell carcinoma** [particularly cervical or anal due to HPV] **Lymphoma**

Answer 5

**Tonsilitis** **Definition** Acute inflammation of the parenchyma of the palatine tonsils **Epidemiology** V common More common in children- five to fifteen y/o **Aetiology** **- viral:** rhinovirus, coronavirus, adenovirus [associated with infectious mononucleus infection too] **- bacterial:** group A streptococcus, mycoplasma pneumoniae, neisseria gonorhhae **Symptoms and signs** Pain on swallowing Tonsilar exudate Tonsilar swelling/enlargment and erythema Sudden onset sore throat Fever \>38C Anterior cervical lymphadenopathy **Investigations** Clinical diagnosis- history, exam, basic obs **How to distinguish between viral and bacterial?** *_Centor criteria_* Fever\>38C Tonsilar exudate Anterior cervical lymphadenopathy/lymphadenitis- painful No cough

Answer 6

**Common cold** **Definition** Mild, self limiting, viral upper resp tract infection **Epidemiology** V common **Aetiology** Viral infection In order of most to least common viruses: Rhinovirus [50%] Coronavirus Influenza Parainfluenza Respiratory syncitial virus **Signs** and **Symptoms** Runny nose Sneezing Cough Sore throat Fever Headache Malaise **Investigations** Clinical diagnosis FBC, throat swab, sputum culture, CRP, CXR- consider but rare **Management** Symptomatic supportive: Analgesia Antipyretic Hydration Decongestant [oxymetazozline nasal, ipratropium nasal] Sometimes: anti tussive, antihistamine

Answer 7

**Abscess** **Definition** Collection of pus in a tissue, organ or cavity created by fibrosis **Aetiology** Usually bacteria - External [on skin]= Staph aureus Rarely - parasites, foreign objects **Types** **Externa**l- Skin - Cutaneous - Subcutaneous Internal - Lung - Brain - Kidneys - Perianal [diabetes, IBD] - Tonsils - Teeth - Incisional **Signs and symptoms** **- External** Erythema Hot Painful Oedema/swelling Loss of function - aka dolor, calor, rubor, tumor, functio laetia **- Internal** Systemic signs Fever Pain **Investigation** Clinical diagnosis- history, exam, obs Ultrasound can help **Management** External/uncomplicated: Aspiration Incision and drainage Severe/multiple infection sites/cellulitis/sepsis/rapid progression**:** Antibiotics Incision and drainage Excision if severe