Infection: small conditions

Question 1

The commonest late stage AIDS infection

Presentation, diagnosis and management

Answer 1

Pneumocystis jiroveci pneumonia (PJP)

Presentation: dry cough + increasing breathlessness

Diagnosis: CD4 <200, CXR, induced sputum or bronchoscopy for PCR

Management: cotrimoxazole, pentamidine (PJP prophylaxis for all patients with CD4<200)

Question 2

A common cause of death during influenza

Diagnosis + risk assessment

Answer 2

Secondary bacterial pneumonia

Diagnosis: CXR (send if flu + fever for >4days)

Assessment of risk of death in next 30 days:
C-onfusion
U-rea >7mmol/l
R-espiratory rate > 30
B-lood pressure (diastolic<60 or systolic <90)
>65-years old

Question 3

The commonest cause of bacterial food poisoning in the UK

presentation

Answer 3

Campylobacter gastroenteritis

Presentation: up to 7 days incubation, (severe) abdominal pain, infection clears within 3 weeks

(<1% = invasive)

Question 4

Most common travel related gastroenteritis

Presentation + diagnosis

Answer 4

Salmonella Gastroenteritis

Presentation: incubation period<48hours, diarrhoea lasts <10days

Diagnosis: blood/Stool culture(screened as a lactose non-fermenter)

Question 5

Most common antibiotic associated diarrhoea

pathophysiology, causative antibiotics, diagnosis, prevention + management

Answer 5

Clostridiodes difficile diarrhoea

Overgrowth of C. diff –> production of enterotoxin (toxA) and cytotoxin (toxB)

Antibiotics: cephalosporins, co-amoxiclav, clindamycin, ciprofloxacin

Diagnosis: sigmoidoscopy, stool culture and toxin detection

Prevention: avoid the 4 C’s, isolate symptomatic patients

Management: 
stop antibiotic (if possible)
Oral metronidazole
Oral vancomycin (if severe)
Stool transplants
Surgery

Question 6

Acute haemorrhagic diarrhoea caused by shiga toxin producing bacteria

Pathophysiology, presentation, identification + management

Answer 6

E. Coli O157

Path: bacteria produced shiga toxin which enters the blood + stimulates platelet activation which can cause HUS

Presentation: frequent, bloody stools

Identification: non-sorbitol fermenter (unlike other e. coli)

Management: strict isolation, DO NOT use antibiotics

Question 7

A disease of childhood/travel which may result in HUS

Management

Answer 7

Shigellosis (shigella infection)

Management: quinolone (resistance is developing)

Question 8

Syndrome caused by platelet activation stimulated by shiga toxin

Presentation, diagnosis + treatment

Answer 8

Haemolytic-Uraemic Syndrome (HUS)
= haemolytic anaemia, renal failure + thrombocytopenia

Presentation = onset 5-9 days after onset of diarrhoea, lethargy, fever, seizures

Diagnosis: ↓platelet count

Treatment: plasmapheresis, IVIG

((a common complication in kids + elderly))

Question 9

Gastroenteritis caused by a type of protozoa native to the UK carried by cattle/dogs

Spread, presentation, diagnosis + management

Answer 9

Giardia duodenalis

spread: direct contact or faecal-oral

Presentation: diarrhoea, gas, malabsorption, constipation

Diagnosis:
• Stool microscopy: cysts (trophozoites die too quickly)
• Duodenal biopsy: trophozoites tightly bound to villi
• String test: trophozoites

Management: metronidazole, tinidazole

Question 10

Gastroenteritis caused by a type of protozoa native to the UK carried by >150 species of mammal

spread, presentation + diagnosis

Answer 10

Cryptosporidium parvum infection

Spread: faecal-oral

Presentation: diarrhoea, vomiting, abdominal pain

Diagnosis: Microscopy=oocysts

Question 11

Infection caused by an imported protozoa

Answer 11

Entamoeba histolytica infection

Presentation: 
Invasive extra-intestinal amoebiasis = liver/pulmonary/brain abscess presenting months/years later
Amoebic dysentery (rarer) = mimics UC

Diagnosis: Stool microscopy (trophozoites, cysts), serum antibody detection

Management: metronidazole, followed by furamide (a luminal agent) to clear colonisation

Question 12

A travel related infection caused by intracellular bacteria

presentation, diagnosis, management

Answer 12

Rickettsiosis

Presentation: abrupt onset swinging fever, headache, confusion, endovasculitis, macular/petechial rash

Diagnosis: serology

Management: tetracycline

Question 13

Diseases such as ebola, lassa fever…

max incubation period, treatment

Answer 13

Viral haemorrhagic fevers

maximum incubation period = 3 weeks

Treatment: supportive, high security infection unit

Question 14

A disease caused by flavivirus transmitted by daytime-biting Aedes mosquitos

presentation, complications, management

Answer 14

Zika

Presentation: mild symptoms (headache, rash, fever, malaise, conjunctivitis, joint pains)

Complications: microcephaly in pregnancy, Guillain-Barre

Management: mosquito control measures

Question 15

Benign staph. aureus infection of hair follicles

treatment

Answer 15

Folliculitis

treatment: nothing, antibacterial washes/ointments

Question 16

Inflammatory nodules of single hair follicles, extending to dermis and subcutaneous tissue (commonly referred to as boils)

causative organism, areas usually affected + management

Answer 16

Furunculosis

causative organism: staph aureus

Usually affects moist, hairy, friction prone areas

Management: none, topical antibiotics, oral antibiotics (if not improving)

Question 17

Large abscess involving multiple adjacent hair follicles

presentation + management

Answer 17

Carbuncle

presentation: purulent material may be spontaneously expressed from multiple sites, systemic features

Management: admission to hospital, IV antibiotics, surgery

Question 18

A superficial bacterial skin infection affecting children of 2-5 years

causative organism, presentation and management

Answer 18

Impetigo

causative organism: staph aureus/strep pyogenes

presentation: erythematous erosion with distinctive honey coloured crust
management: usually none, topical antibiotics, oral antibiotics (if large area)

Question 19

Infection of the upper dermis with lymphatic involvement

causative agent, presentation + management

Answer 19

Erysipelas

causative agent: usually strep pyogenes

Presentation: painful, hot, indurated (hardened) erythema, well-defined elevated margins. fever + lymphadenopathy

Management: anti-staph and anti-strep antibiotics (admission + IV if extensive)

Question 20

Infection of the epidermis, deep dermis and subcutaneous tissue, a possible source of bacteraemia

causative agent, presentation + management

Answer 20

Cellulitis

causative agent: strep. pyogenes/staph aureus

Presentation: painful, hot, spreading, ill-defined, non-palpable erythema. fever + lymphadenopathy

Management: Penicillins (admission + IV if extensive). Treat pre-disposing factors (e.g. lymphoedema, ATHLETES FOOT, immunosuppression, ulceration)

Question 21

A soft tissue infection known as “flesh-eating disease”

presentation, diagnosis + management

Answer 21

Necrotizing fasciitis

Presentation: rapid onset. erythema –> extensive oedema –> severe pain. haemorrhagic bullae, skin necrosis, systemic features (fever, hypotension, tachycardia, delirium, multi-organ failure)

Diagnosis: imaging (may delay treatment)

Management: Broad spectrum antibiotics (flucloxacillin, gentamicin, clindamycin). surgery

Question 22

Purulent infection deep within striated muscle (Often manifests as an abscess)

causative organism, presentation, management

Answer 22

Pyomyositis

causative organism: staph aureus (+/- other organisms)

Presentation: woody induration of affected muscle, fever

Management: urgent attention, possibly surgery

Question 23

Bacterial infection of bursae

causative organism (+route), presentation + diagnosis

Answer 23

Septic bursitis

Causative organism: staph aureus (often spreads from adjacent skin infection)

Presentation: pain on movement, fever

Diagnosis: fluid aspiration

((Most commonly affected = olecranon and patellar bursae))

Question 24

Infection of the synovial sheaths that surround tendons

causative agent, presentation, management

Answer 24

Infectious tenosynovitis

Commonest causative agent: staph aureus/ streptococci (often incited by penetrating trauma)

Presentation: erythematous swelling, finger held in a semi-flexed position, tenderness over length of tendon, pain on extension

Management: empiric antibiotics, review by hand surgeon ASAP

((most commonly affects the tendon sheaths of flexor muscles of the hand))

Question 25

A diffuse erythematous rash caused by a particular strain of staph aureus producing exfoliative toxins presentation, diagnosis + management

Answer 25

Staphylococcal (s. aureus) scalded skin syndrome Presentation: widespread bullae (rupture easily), exfoliation/desquamation, skin tenderness, fever and irritability Diagnosis: skin biopsy Management: admission, IV fluids + antibiotics ((mostly affects kids <5, esp. newborns))

Question 26

A toxin produced by some strains of Staphylococcus aureus management

Answer 26

Panton-Valentine Leukocidin (PVL) toxin = a gamma haemolysin (causes lysis of RBCs) Management: urgent antibiotics ((usually affects children and young adults))

Question 27

A fungal infection, usually affecting the mouth, skin and nails. May be a presenting factor of immunodeficiency disorders causative organism, presentation, management

Answer 27

Mucocutaneous candidiasis Causative organism: candida albicans (a yeast) Presentation: oral thrush, fungal toenail, skin redness + itching (e.g. btw fingers/nappy rash) Management: topical/oral antifungals

Question 28

Candida in the bloodstream, mostly of endogenous origin (candida = a gut commensal) diagnosis + management

Answer 28

Invasive candidiasis Diagnosis: blood culture, screening of high risk patients Management: echinocandins + fluconazole ((a common bloodstream infection, mortality up to 40%))

Question 29

Chronic pulmonary infection of aspergillus fumigatus affecting patients with underlying chronic lung conditions presentation + diagnosis

Answer 29

Chronic Pulmonary Aspergillosis Presentation: pulmonary exacerbations (not responding to antibiotics), lung function decline, increased respiratory symptoms Diagnosis: sputum culture, aspergillus specific IgG and IgE

Question 30

Immunological response to a variety of Aspergillus fumigatus antigens in CF patients Presentation + diagnosis

Answer 30

Allergic Bronchopulmonary Aspergillosis Presentation: deterioration of lung function and increasing respiratory symptoms Diagnosis: CXR, ↑IgE, +ve skin test

Question 31

A fungal mass that grows in the lung cavities, usually of patients with underlying cavitary lung disease Possible underlying cavitary lung diseases

Answer 31

Pulmonary aspergilloma Possible underlying cavitary lung diseases: - TB - Sarcoidosis - Bronchiectasis ….

Question 32

Pulmonary infection by Cryptococcus (a yeast found in organic matter) Presentation, diagnosis + management

Answer 32

Cryptococcosis Presentation: asymptomatic --> pneumonia, can disseminate to the brain causing meningoencephalitis in HIV/AIDS patients Diagnosis: CSF/blood culture, CSF/blood screen for cryptococcus antigen Management of cryptococcal meningitis: amphotericin B + flucytosine, followed by fluconazole

Question 33

Causes of meningism

Answer 33

Meningitis Sub-arachnoid haemorrhage Migraine Other infections: influenza, tonsilitis, pneumonia, sinusitis, UTI

Question 34

Intravenous catheter (venflon) associated infections commonest causative organism, risk factors, diagnosis, treatment

Answer 34

organism: staph aureus risk factors: continuous infusion >24hrs, cannula in situ >72hrs diagnosis: clinical/blood cultures treatment: remove cannula, express pus, 14 days antibiotics ((local skin infection --> soft tissue infection --> cellulitis/ tissue necrosis/ bacteraemia)) ((associated bacteraemia may seed to cause endocarditis/ osteomyelitis))

Question 35

Acute viral infection of the CNS affecting most mammals, spread by a bite by an infected animal (pathophysiology, presentation, diagnosis, management)

Answer 35

Rabies Path: virus enters peripheral nerves and migrates through them to the CNS + brain Presentation: long incubabtion (weeks-months), paraesthesia at site, ascending paralysis, acute encephalitis Diagnosis: serology, CSF/saliva PCR Management: Pre-exposure = active immunisation Post-exposure = post exposure prophylaxis: - human rabies immunoglobulin (HRIG) - active rabies vaccine (4 doses over 14 days) sedation + intensive care ((always fatal if untreated))

Question 36

A highly contagious zoonosis spread through unpasteurised milk, placenta and close contact of infected farm animals (presentation, diagnosis, management)

Answer 36

Brucellosis Presentation: Acute = 1-3 weeks, Subacute = >1 month, Chronic = months-years May be asymptomatic Fever, flu-like symptoms, arthralgia/arthritis, splenomegaly Diagnosis: culture, serology Management: Long acting doxycycline (2-3 months) + rifampicin/ gemtamicin (for 1st week(s))

Question 37

Rare bacterial infection found in animal urine, transmitted to humans through direct contact of a break in the skin with animals or contaminated water/mud (an occupational/recreational disease) (presentation, diagnosis, management)

Answer 37

Leptospirosis Presentation: fever, myalgia, headache, abdo pain, meningism, hepatitis Diagnosis: ELISA serology, PCR, culture (all are sub-optimal and take time, diagnosis usually based on history of exposure) Management: mild = doxycycline severe = IV penicillin

Question 38

A travel related bacterial infection of the GI tract, spread through poor sanitation and unclean drinking water (causative agent, presentation, diagnosis, management)

Answer 38

Typhoid (enteric) fever Causative agent: salmonella typhi Presentation: (4 weeks) Fever, constipation progressing to diarrhoea, GI bleeding Diagnosis: cultures (blood, urine, stool, bone marrow) Management: Oral azithromycin IV ceftriaxone if complicated/ absorption concerns

Question 39

a disease caused by an arbovirus spread by daytime-biting Aedes mosquitoes in Asia, the Americas and the Caribbean (Presentation, complications, diagnosis, management, prevention)

Answer 39

Dengue Presentation: fever, maculopapular rash, haemorrhagic signs (petechiae, purpura...) Complications: dengue haemorrhagic fever, dengue shock syndrome Diagnosis: FBC (thrombocytopenia, leukopenia) , PCR, serology Management: supportive (no specific therapeutic agents) For complications: IV fluids, FFP, platelets Prevention: dengvaxia vaccine, mosquito control

Question 40

A disease of the urinary tract or the intestines caused by parasitic flatworms, transmitted by freshwater snails to swimmers (presentation, diagnosis, management)

Answer 40

Schistosomiasis Presentation: Swimmer's itch 24-48hrs May be asymptomatic/latent for months-years Acute: fever, urticaria, cough, diarrhoea, abdo pain, and/ or Chronic: haematuria/dysentery Diagnosis: antibody tests, ova in stool/urine, rectal snip Management: Praziquantel (2 doses), prednisolone if severe

Question 41

A rare but life-threatening condition caused by toxins secreted by staphylococcal/ streptococcal bacteria (cause, presentation, diagnosis, management, mortality)

Answer 41

Toxic Shock Syndrome (TSS) Cause: skin or soft tissue infection, extended tampon use Presentation: fever, hypotension, diffuse macular rash (blanches), desquamation, Strep: --> shock + multiorgan failure Diagnosis: microscopy + culture, serotyping Management: Supportive care in ICU, Early empirical and then specific antibiotics, If streptococcal: urgent surgical debridement of infected tissues Staphylococcal TSS mortality = 5% Streptococcal TSS mortality = 50%

Question 42

Rapid and extensive fungal growth in the alveoli caused by inhalation of an airborne mould. Often a presenting symptom of immunodeficiency (causative agent, presentation, diagnosis, management)

Answer 42

Acute invasive pulmonary aspergillosis Causative agent: Aspergillus fumigatus Presentation, non-specific systemic illness, fever, may present outside the lungs Diagnosis: BIOPSY, sputum culture, CT chest, FBC - neutropenia Management: Azoles (voriconazole and isavuconazole) ((acute mortality = 50%, subacute = 20-50%))

Question 43

An infectious disease caused by the spirochaete Borrelia burgdorferi spread by ticks presentation, diagnosis, management

Answer 43

Lyme disease Presentation: stage 1: erythema migrans + flu-like symptoms stage 2: nerve palsies stage 3: meningism, encephalitis, polyneuropathies, psychosis, arthritis, chronic fatigue syndrome, cardiac complications Diagnosis: ELISA serology (+ investigation of complications) Management: doxycycline (can be given prophylactically after a known tick bite)

Question 44

Management of staphylococcus aureus bacteraemia

Answer 44

MSSA: IV flucloxacillin MRSA/penicillin allergy: IV vancomycin ((staphylococcus aureus = commensal bacteria))