Untitled Quiz

Infectious Diseases Summary

• Respiratory Infections:

  • Community-acquired pneumonia (mild): Amoxicillin
  • Community-acquired pneumonia (moderate): Amoxicillin + Clarithromycin
  • Community-acquired pneumonia (severe): Co-amoxiclav + Clarithromycin
  • Pneumocystis Jirovecii pneumonia (prev as "P. Carinii"): Co-trimoxazole (trimethoprim + sulfamethoxazole)
  • Tuberculosis (TB): First 2 months (RIPE): Rifampicin, Isoniazid, Pyrazinamide, Ethambutol. Next 4 months (RI): Rifampicin and Isoniazid.
  • Aspiration pneumonia (community acquired): Amoxicillin + Metronidazole

• Pneumonia:

  • Treatment for penicillin allergy: Clarithromycin or Doxycycline.
  • Caution with statins: Avoid clarithromycin if patient is taking a statin due to increased risk of rhabdomyolysis

• Central Nervous System Infections:

  • Out-of-hospital meningitis: Benzylpenicillin
  • In-hospital meningitis: Cefotaxime IV or Ceftriaxone IV
  • Listeria meningitis: Amoxicillin + Gentamicin
  • Cryptococcal meningitis: Amphotericin B
  • Meningitis prophylaxis (for contacts): 1st line: Ciprofloxacin. 2nd line: Rifampicin
  • Empirical treatment for meningitis (patient >60): IV ceftriaxone and IV amoxicillin

• Gastrointestinal Infections:

  • Salmonella: Ciprofloxacin OR Cefotaxime
  • Shigella/Campylobacter: Erythromycin OR Azithromycin OR Clarithromycin OR Ciprofloxacin
  • Clostridium difficile (Pseudomembranous colitis):
    • Mild: Oral Metronidazole
    • Severe: Vancomycin
  • Helicobacter pylori: OAC or OAM (Omeprazole, Amoxicillin, Clarithromycin or Metronidazole)

• Clostridium difficile vs Norovirus:

  • Clostridium Difficile: Severe diarrhoea + recent use of broad spectrum antibiotics + spreads easily in wards
  • Norovirus: Severe diarrhoea + spreads easily in wards

• Ear, Nose & Throat Infections:

  • Acute bacterial otitis media: Amoxicillin
  • Upper respiratory tract infection (Pharyngitis, Tonsillitis, Laryngitis): Phenoxymethylpenicillin

• Laryngitis:

  • Investigation: None required.

• Skin, Joint, and Other Infections:

  • Cellulitis: Flucloxacillin
  • Mastitis: Flucloxacillin
  • Diabetic Foot Infection: Specific treatment varies
  • Scabies: Permethrin 5% topical
  • Septic Arthritis: Flucloxacillin, Vancomycin (MRSA)
  • Osteomyelitis: Specific treatment varies
  • Toxoplasmosis: Pyrimethamine + Sulfadiazine

• Oral Thrush (Oral candidiasis):

  • Features: Thick white marks, inflamed mouth/tongue, can be rubbed out, red inflamed sore mouth angles.
  • Contributing factors: Immunosuppression (diabetes, recent antibiotic use, regular steroids), smoking, elderly, pregnancy.
  • Treatment: Stop smoking, good inhaler technique and hygiene (e.g., use a spacer and rinse mouth after use), 1st line: oral miconazole gel, oral fluconazole 50mg OD 7 days in severe cases.

• Leukoplakia:

  • Features: Raised edges, bright white patches, sharply defined, cannot be rubbed out.
  • Contributing factors: Smoking history.
  • Investigation: Biopsy (premalignant for SCC).
  • Treatment: Smoking cessation, observe or surgical excision depending on biopsy result

• Streptococcus Pneumoniae:

  • Facts: Most common cause of pneumonia, gram +ve diplococci.
  • Features: Productive cough, fever, chest tightness, unilateral basal crackles on auscultation, unilateral lobar consolidation on X-ray.
  • Association: Herpes Labialis.

• Different Types of Pneumonia:

  • Pneumococcal streptococcal: Herpes Labialis, typical features of community-acquired pneumonia, productive cough, fever, unilateral basal crackles, unilateral basal consolidation.
  • Mycoplasma: Erythema multiforme, atypical features (young adult, dry cough), bilateral consolidation, patchy consolidation of 1 lower lobe.
  • Pneumocystis jirovecii: HIV with CD4 < 200, + desaturation on exercise, dry cough, bilateral consolidation, exertional dyspnea.
  • Staph. aureus: Pneumonia after influenza (flu), common in IV drug abusers and elderly, bilateral cavitation.
  • Legionella: Pneumonia after exposure to water (e.g., hotel), low sodium, low lymphocytes, bibasal consolidation, macrolides/tetracyclines are usual treatment of choice.
  • Klebsiella: Cavitating pneumonia, particularly upper lobe, bacterial pneumonia.

• Type of Pneumoniae:

  • HIV patient with lobar consolidation (CD4 count 350): Streptococcus pneumoniae
    • Child with purulent CSF: Streptococcus pneumoniae (if neisseria is not an option)
    • IV drug user with bilateral cavitation and recent flu-like symptoms: Staphylococcus aureus

• Tuberculosis:

  • Facts: Caused by Mycobacterium Tuberculosis (acid-fast bacilli), travelling history, high-risk groups (homeless, drug abusers, smokers, low socioeconomic class).
  • Diagnosis: Sputum staining for acid-fast bacilli, Bronchoalveolar lavage, Gastric lavage (if sputum not obtained).
  • High risk factors: Homeless, drug abuser, smoker, low socioeconomic class.
  • Features: Chronic productive cough, hemoptysis (coughing up blood), weight loss (cachexia), fatigue, night sweats, small area of caseating granulomas, upper lobe consolidation, infiltration, cavitation on chest X-ray, cervical/supraclavicular lymph nodes may be initially tender, firm and discrete on palpation but later become suppurative.
  • Main symptoms of Pulmonary tuberculosis: Central (appetite loss, fatigue); Lungs (chest pain, coughing up blood, prolonged cough), Skin (night sweats, pallor).
  • Screening for contacts of tuberculosis patient: Mantoux test for contacts who have not been vaccinated with BCG, Interferon gamma test for contacts who have been vaccinated with BCG.
  • Treatment: First 2 months (RIPE): Rifampicin, Isoniazid, Pyrazinamide, Ethambutol. Next 4 months (RI): Rifampicin, Isoniazid.
  • Directly Observed Therapy (DOT): For patients who need support to manage TB (homeless, imprisoned, drug/alcohol misuse, patients not adherent to therapy, those too ill to adhere to therapy). Toxoplasmosis can present with splenomegaly and cervical lymphadenopathy but weight loss isn't seen.
  • Tuberculous Lymphadenitis: Contributing factors (traveling history, especially to/from India), features (fever, cough, cervical lymphadenopathy, caseating granuloma in lymph nodes). Difference from sarcoidosis and Crohn's (non-caseating granuloma).
  • Laryngeal TB: Contributing factors (IV drug abuse, low socioeconomic status), features (fever, cough, cervical lymphadenopathy, hoarseness, dysphagia, weight loss), 35 year old homeless man with these symptoms.
  • Side effects of Anti-TB drugs: Rifampicin (uric acid increase, gout risk, peripheral neuritis, hepatitis), Streptomycin (visual problems e.g., red-green discrimination, ↓visual activity, optic neuritis), Isoniazid (visual problems, ototoxic, potential deafness, contraindicated in pregnancy), Ethambutol (uric acid increase, gout risk, visual problems, ototoxic, potential deafness). Streptomycin is contraindicated during pregnancy.

• Scabies:

  • Facts: Organism: Sarcoptes scabiei (parasite), transmitted by skin-to-skin contact, causes allergic reaction, pruritus (itching) is NOT the infection.
  • Features: Linear tracks (burrows), severe pruritus (particularly at night), typically found in skin folds (e.g., wrists, finger webs, elbow, axilla, areola, genitalia).
  • Treatment: Permethrin 5% cream, treat all close contacts simultaneously.
  • Keywords: Sarcoptes, very itchy, linear tracks on skin, allergic reaction, permethrin.

• Gastroenteritis:

  • Features: Nausea, vomiting, diarrhea (with or without blood), abdominal pain.
  • Investigations: Stool microscopy, culture and sensitivity, FBC, renal function, electrolytes.
  • Treatment: Usually conservative (hydration). Severe bloody diarrhea: Campylobacter jejuni (Clarithromycin), Salmonella (Ciprofloxacin).
  • UK patient return to work: 48 hours after last symptom (diarrhea or vomiting).

• Meningitis (general):

  • Delayed complication: Hearing loss
  • MUST arrange hearing test: No later than 4 weeks after treatment.

• Meningitis (in babies and toddlers):

  • Features/Symptoms: Fever, cold hands and feet, refusing food and vomiting; Fretful, dislike being handled; Unusual crying, moaning; Pale, blotchy skin; Tense, bulging fontanell (soft spot); Drowsy, floppy, unresponsive, Rapid breathing and grunting; Stiff neck; dislike bright lights; Rash; seizures.

• Kaposi Sarcoma:

  • Facts: Cancer of connective tissue, most commonly caused by HIV/AIDS
  • Features: Red, purple, brown, or black nodules or papules; usually non-painful; common sites – mouth, nose, throat; can grow internally (e.g., lungs, GI tract).
  • Risk Factors: Homosexual, Mediterranean, Jewish, Bisexual, AIDS patient.

• Chicken Pox:

  • Cause: Varicella zoster virus (VZV).
  • Infectious Route: Very contagious, mainly via respiratory route (airborne), transmitted by direct contact with vesicles. Dried out/crusted vesicles do not transmit.
  • Infectious Period: 2 days before rash; 5 days after rash first appears; stop when vesicles dry out and crust.
  • Features: Fever (38-39°C), pruritic (itchy) rash, rash stages (macules, papules, vesicles, dry crusts); usually starts on face or trunk, then spreads over entire body.
  • Management (adults): Reassurance + supportive measures (paracetamol for fever, antihistamines and calamine lotion for itching) + Oral antibiotic if superimposed infection is suspected.
  • Management (children < 12): Reassurance + supportive measures (paracetamol for fever, antihistamines and calamine lotion for itching) + Oral antibiotic if superimposed infection is suspected.
  • Management (exposure): Oral aciclovir.
  • Management (immunocompromised): VZIG, acyclovir, assess risk, serology for varicella immunity, immunocompromised- HIV positive, diabetic, on long-term steroids.

• Shingles:

  • Facts: Reactivation of VZV. Immunocompromised old patients. Chickenpox at initial infection
  • Features: Painful skin rash with blisters in localized area.
  • Management: Obtain serology for varicella immunity in immunocompromised patients. Immunocompromised- HIV positive, diabetic, on long-term steroids.
  • Treatment: Aciclovir, pain management

• Ramsay Hunt Syndrome:

  • Facts: Reactivation of VZV, localized in geniculate ganglion of the facial nerve (7th CN).
  • Features: Facial palsy (ipsilateral facial palsy, loss of taste), otalgia (ear pain), tinnitus, vertigo, unilateral hearing loss, painful rash or vesicles around ears or on auditory canal.
  • Treatment: Oral aciclovir, oral corticosteroid, amitriptyline for pain.

• Herpes Zoster Ophthalmicus:

  • Facts: Reactivation of VZV, localized in ophthalmic branch of trigeminal nerve (5th CN).
    • Features: Conjunctivitis. Keratitis, painful rash or vesicles around eyes, Hutchinson's Sign (vesicles on the tip of the nose).
  • Treatment: Oral aciclovir, oral corticosteroids, same day ophthalmology review, possible IV aciclovir for severely immunocompromised or systemic issues.

• Lyme Disease (Lyme borreliosis):

  • Beginning Stage: Erythema migrans (erythematous, painless, non-itchy rash), fever, headache, myalgia, general aches.
    • Later Stage: Facial paralysis, encephalitis, meningitis, AV heart block, myocarditis, arthritis.
  • Diagnosis: Check for antibodies to Borrelia burgdorferi.
  • Treatment: Doxycycline or Amoxicillin (if contraindicated, e.g., pregnancy), Ceftriaxone (in disseminated disease).

• Meningitis Treatment:

  • General: Health protection team must be notified immediately. Look out for: Arthralgia, muscle aches, cold periphery, pale or mottled skin, SOB, rash, photophobia, severe headache, neck stiffness, septicemia.
  • GP setting: IM or IV Benzylpenicillin.
  • Hospital setting: IV Ceftriaxone or Cefotaxime.
    • Allergy to Penicillin: Chloramphenicol.

• Meningitis (Listeria): Amoxicillin or Ampicillin + Gentamicin

• Meningitis (Cryptococcal): Amphotericin B

• Meningitis prophylaxis: Ciprofloxacin, Rifampicin

• Schistosomiasis:

  • Features: Hx of travel to Africa, (mostly), Haematuria, urinary bladder calcification, ulceration and obstructive uropathy, increased bladder cancer risk, hepatomegaly. Caused by 2 species (S. mansoni, S. haematobium).
  • Investigations: X-ray (urinary bladder calcification), ultrasounds (hydronephrosis), thickened bladder wall), CT scan (urinary bladder calcification, obstructive uropathy).
  • Similar organisms: Schistosoma mansoni.

• Malaria:

  • Features: Hx of travel to Africa, intermittent fevers, rigors, headache, malaise, cough, myalgia, gastrointestinal upset, hepatosplenomegaly, jaundice.
  • Investigations: Microscopy of thick and thin blood film (most accurate), full blood count, rapid diagnostic test (adjunct to blood films, not a replacement).
  • Important note: Prophylaxis does not prevent all types of malaria.
  • Cerebral Malaria: Hx of travel to malaria-affected areas, meningitis-like symptoms (fever, chills, neck stiffness, vomiting, impaired consciousness), anaemia. Different from meningitis.
  • Treatment: Prophylaxis for Malaria (Chloroquine for non-falciparum malaria, Primaquine).

• Needle Stick Injuries:

  • Protocol: Wash with soap and water, encourage bleeding, investigate for blood-borne infections.
  • Low risk: Safe sexual practices, does not use IV drugs.
  • High risk: IV drug abusers, drug addicts. PEP, healthcare pro for HBV surface antibody, offer HBV booster if needed.
  • Follow-up: Check for HIV and HCV in 6 weeks. Always test for HIV, HCV, and HBV.

• Vaccine (HIV positive patients): Avoid BCG, MMR, and Yellow fever vaccines.

• Tetanus Prophylaxis:

  • Wound risk: High risk (dirty, contaminated, compound fracture), low risk (clean).
  • Immunization status: Fully immunised and up-to-date, unknown or incomplete, need to be completed.

• Abscess:

  • Features: High fever, erythematous skin swelling, neck abscess if large enough can cause dysphagia.
  • Treatment: IV antibiotics, incision, drainage. If patient is unwell, sepsis must be considered.

• Whipple's Disease:

  • Facts: Rare multisystem disorder, caused by Tropheryma whipplei infection.
  • Features: Malabsorption (weight loss and diarrhea), large joint arthralgia, lymphadenopathy, skin hyperpigmentation and photosensitivity, pleurisy, pericarditis, neurological symptoms (rare: ophthalmoplegia, dementia, seizure, ataxia, myoclonus).
  • Investigations: Jejunal biopsy shows stunted villi, macrophages containing periodic acid-Schiff (PAS) granules.
  • Treatment: Co-trimoxazole for a year, preceded by a course of IV penicillin.

• Other Information:

  • Important Investigation Results: Jejunal biopsy for Whipple's, celiac disease (villous atrophy, crypt hyperplasia, lymphocytosis), lymphoma in celiac patients (lymphomatous infiltrates).
  • Mastitis/Breast Abscess: Common cause Staph. Aureus, use notes on breastfeeding (Avoid/Continue).
  • Rabies: Vaccination indicated only for bat bites.
  • Cellulitis Treatment: First line – Flucloxacillin, Doxycycline, Erythromycin, Clarithromycin. Other options – Clindamycin.