Sepsis, pneumonia, meningitis, HIV, TB, hepatitis, STIs, and antimicrobial stewardship with UK resistance patterns.
The ability of microorganisms to resist the effects of antimicrobial agents, rendering standard treatments ineffective. Declared a global health emergency by WHO, with an estimated 1.27 million deaths directly attributable to AMR worldwide in 2019. The UK 5-year AMR action plan targets a 50% reduction in inappropriate antibiotic prescribing.
A multidisciplinary framework to optimise antimicrobial use, improve outcomes, reduce adverse effects, and contain resistance. UK hospitals use stewardship teams, formulary restrictions, and audit with feedback aligned to NICE and UKHSA principles.
Infections caused by *Candida* species ranging from mucosal disease to candidaemia and deep organ infection. *Candida albicans* remains common, but non-albicans species and azole resistance are increasingly relevant in hospitalised patients.
Urinary tract infection occurring in a patient with an indwelling urethral catheter, usually due to biofilm-associated uropathogens. Diagnosis and management differ from uncomplicated cystitis; removal of the catheter where possible is central to treatment.
Acute bacterial skin infection involving the dermis and subcutaneous tissue, most commonly caused by beta-haemolytic streptococci and S. aureus. Presents with erythema, warmth, swelling, and pain, usually affecting the lower limbs. Managed with oral or IV antibiotics per NICE NG141.
Common bacterial STI caused by *Chlamydia trachomatis*, often asymptomatic but able to cause urethritis, cervicitis, PID, and infertility. First-line treatment in the UK is typically doxycycline for 7 days.
Toxin-producing anaerobic infection (now Clostridioides difficile) causing antibiotic-associated diarrhoea and pseudomembranous colitis. Most common healthcare-associated infection. Treated with oral vancomycin per NICE NG199. Severe cases may require colectomy.
Respiratory illness caused by SARS-CoV-2, ranging from asymptomatic infection to severe pneumonia, ARDS, and multi-organ failure. Vaccines, antivirals (nirmatrelvir/ritonavir), and dexamethasone have transformed outcomes since the pandemic onset in 2020.
Ubiquitous herpesvirus (HHV-5) causing asymptomatic infection in most immunocompetent individuals but severe disease in immunocompromised (transplant recipients, HIV with CD4 <100) and congenital infection. Manifestations include retinitis, colitis, pneumonitis, and encephalitis.
Defined as fever >38.3°C on several occasions, lasting >3 weeks, with no diagnosis despite 1 week of inpatient investigation (Petersdorf & Beeson criteria). The three main categories are infection (~30%), malignancy (~20%), and autoimmune/inflammatory conditions (~20%). Approximately 10–15% remain undiagnosed despite thorough investigation.
A spectrum from superficial mucocutaneous candidiasis and dermatophyte infections to invasive mould disease in immunocompromised hosts. Management depends on immune status, site, and species identification with susceptibility testing where available.
Infections acquired during or as a result of healthcare delivery, not present on admission. Include MRSA bacteraemia, C. difficile infection, catheter-associated UTI, ventilator-associated pneumonia, and surgical site infections. UK mandatory surveillance has driven significant reductions through infection prevention and antimicrobial stewardship.
Blood-borne viral hepatitis caused by HBV; can present as acute icteric hepatitis or evolve into chronic infection with cirrhosis and hepatocellular carcinoma risk. UK management includes antiviral suppression for chronic disease and neonatal vaccination programmes.
Blood-borne RNA virus causing acute and chronic hepatitis; most cases are asymptomatic until advanced liver disease. Direct-acting antiviral (DAA) regimens achieve >95% cure rates in the UK when adherence and regimen selection are correct.
Infection with herpes simplex virus type 1 (orolabial) or type 2 (genital), causing painful vesicular lesions. Establishes lifelong latency in sensory ganglia with periodic reactivation. HSV encephalitis is a medical emergency requiring urgent IV aciclovir.
Human immunodeficiency virus (HIV) is a retrovirus that targets CD4+ T cells, leading to progressive immunodeficiency. AIDS is defined as CD4 count <200 cells/µL or an AIDS-defining illness. Modern antiretroviral therapy (ART) achieves viral suppression in >95% and near-normal life expectancy.
Strategies to prevent HIV acquisition including pre-exposure prophylaxis (PrEP) with tenofovir/emtricitabine for at-risk individuals, post-exposure prophylaxis (PEP) following potential exposure, and prevention of mother-to-child transmission (PMTCT).
The UK routine immunisation programme protects against multiple infectious diseases from birth through adulthood. Managed by UKHSA and guided by the Joint Committee on Vaccination and Immunisation (JCVI). Includes primary infant vaccinations (6-in-1, rotavirus, MenB, PCV13), childhood boosters, HPV, and adult programmes (flu, shingles, COVID-19).
Acute infection caused by Epstein-Barr virus (EBV/HHV-4) characterised by fever, pharyngitis, and lymphadenopathy (the classic triad). Common in adolescents and young adults. Complications include splenic rupture, hepatitis, and airway obstruction. Associated with Burkitt lymphoma, nasopharyngeal carcinoma, and PTLD.
Infection of the endocardium, typically involving heart valves, causing fever, embolic phenomena, and heart failure. *Staphylococcus aureus* and oral streptococci are common; diagnosis integrates blood cultures and echocardiography; treatment is prolonged high-dose bactericidal antibiotics and sometimes surgery.
Acute respiratory infection caused by influenza A or B viruses, characterised by fever, myalgia, cough, and headache. Seasonal epidemics cause significant morbidity and mortality, particularly in the elderly and high-risk groups. Annual vaccination is the primary prevention strategy.
Angioinvasive pulmonary infection caused by *Aspergillus* spp., classically in prolonged neutropenia and transplant recipients. Voriconazole is first-line therapy; diagnosis integrates imaging, galactomannan, and culture.
A parasitic infection caused by Plasmodium species transmitted by Anopheles mosquitoes. P. falciparum causes the most severe form with risk of cerebral malaria, severe anaemia, and death. Approximately 1,500–2,000 imported cases occur in the UK annually.
Highly contagious viral infection caused by the measles morbillivirus, characterised by fever, cough, coryza, conjunctivitis, Koplik spots, and a maculopapular rash. Vaccine-preventable (MMR) but re-emerging due to declining vaccination rates. Notifiable disease in the UK.
Invasive infection with Neisseria meningitidis causing meningitis and/or meningococcaemia (septicaemia). A medical emergency with rapidly progressive course. Non-blanching purpuric rash is the hallmark of meningococcal septicaemia. Case-fatality rate ~5–10% even with optimal treatment.
Methicillin-resistant Staphylococcus aureus is a major healthcare-associated pathogen resistant to flucloxacillin and all beta-lactams via the mecA gene (PBP2a). Causes skin/soft tissue infections, bacteraemia, endocarditis, and surgical site infections. UK rates have declined >80% since mandatory screening and decolonisation programmes.
Acute viral infection caused by mumps virus (Paramyxoviridae) characterised by fever and painful parotid gland swelling. Vaccine-preventable with MMR. Complications include orchitis (20–30% post-pubertal males), meningitis, and pancreatitis. Notifiable disease.
Protozoal and helminth infections acquired in endemic regions or through food/water/vector exposure. UK clinicians encounter imported malaria, intestinal helminths, schistosomiasis, and toxocariasis among travellers and migrants; diagnosis requires geography, eosinophil count, and targeted tests.
Fever developing within weeks of returning from travel abroad requires urgent assessment. Malaria must be excluded in ALL febrile returning travellers from endemic areas — it is the most important diagnosis not to miss. Other causes include dengue, typhoid, viral hepatitis, and viral haemorrhagic fever.
Life-threatening organ dysfunction caused by a dysregulated host response to infection. Defined by the Sepsis-3 criteria (SOFA score ≥2). Affects ~250,000 people per year in the UK with a mortality of 15–20% overall and up to 40–50% in septic shock.
A subset of sepsis with circulatory and cellular/metabolic dysfunction characterised by persistent hypotension requiring vasopressors to maintain MAP ≥65 mmHg and lactate >2 mmol/L despite adequate fluid resuscitation. Carries in-hospital mortality of 40–50%.
A group of infections transmitted by sexual contact, including chlamydia, gonorrhoea, syphilis, HIV, trichomoniasis, and viral hepatitis. UK care emphasises confidential testing, partner notification, and syndrome-based management when empirical therapy is required.
Systemic infection caused by *Treponema pallidum*, presenting in stages (primary, secondary, latent, tertiary) and with neurosyphilis or ocular involvement. Penicillin remains definitive treatment; serological follow-up is essential.
Infection by *Toxoplasma gondii*; usually asymptomatic in immunocompetent hosts but causes retinochoroiditis, cerebral toxoplasmosis in advanced HIV, and congenital infection. Pyrimethamine-based regimens with folinic acid rescue are standard for cerebral disease; specialist care in pregnancy.
Medical specialty encompassing pre-travel risk assessment, travel vaccinations, malaria chemoprophylaxis, and management of post-travel illness. Key considerations include destination-specific risks, mandatory versus recommended vaccines, and travellers' diarrhoea prevention. The Green Book and NaTHNaC provide UK guidance.
Infectious disease caused by Mycobacterium tuberculosis, primarily affecting the lungs but capable of involving any organ. The UK has ~4,500 cases/year, predominantly in urban areas and immigrant populations. Standard treatment is 6 months of combination therapy per NICE NG33.