Common Infections

• What is an infection?

  An infection is the invasion of the body by pathogenic organisms.
• How do infections spread?

  • Airborne
  • Respiratory (droplet)
  • Fomite (touching surfaces)
  • Direct contact
  • Enteric (faecal-oral)
  • Blood borne
  • Vertical (maternal to foetal)
• What does 'resistance' mean in the context of infections?

  Resistance refers to organisms that cause disease being unaffected by antimicrobial medicines.
• What causes resistance to antimicrobial medicines?

  Inappropriate use of antibiotics, such as wrong choice or unnecessary prescriptions, causes resistance.
• What are common sites of bacterial infection?

  Meninges

  Skin/soft tissue

  Catheter related infection

  UTI

  ENT infections

  Pneumonia

  Bloodstream infection

  Abdominal infection
• What are some examples of ENT infections?

  • Otitis media
  • Otitis externa
  • Tonsillitis
  • Laryngitis
  • Epiglottitis
• What is bacteriuria?

  Presence of bacteria in the urine - may be asymptomatic.
• What is the difference between lower and upper UTIs?

  Lower UTIs -> bladder infections (cystitis)

  Upper UTIs -> kidney infections (pyelonephritis).
• What is abacterial cystitis?

  Abacterial cystitis is a diagnosis of exclusion in patients with dysuria without demonstrable infection.
• What is the difference between uncomplicated and complicated UTIs?

  Uncomplicated - normal renal tract structure/function

  Complicated - structural/functional abnormality, increases the risk of a more serious outcome or treatment failure
• What are the common causes of UTI?

  E.coli

  Staph saprophyticus (skin commensal)

  Proteus mirabils

  Klebsiella pneumonia
• What are the RFs of UTIs?

  Diabetes

  Catheter

  Renal stones

  Faecal/urinary incontinence

  Sexual contact

  Dehydration

  Constipation

  Blocked tract
• What are the common signs and symptoms of a UTI?

  Polyuria

  Dysuria

  Urgency

  Suprapubic pain

  Haematuria
• When should a urine dipstick test be performed for UTI diagnosis?

  • Non-pregnant women: Only dip if ONE symptom of UTI.
  • Pregnant women: No dip
  • Men: No dip
  • Catheterized patients: No dip
  • >65 years: No dip
• What is the management for asymptomatic bacteriuria in non-pregnant women/men?

  Do not give antibiotics for asymptomatic bacteriuria.
• What is the treatment for symptomatic, non-pregnant women with a UTI?

  3 day course of nitrofurantoin or trimethoprim (men = 7 day course)

  If 1st line fails -> send urine for culture

  If culture is -ve -> reconsider diagnosis
• What is the management for catheter-associated UTIs?

  Send a midstream urine sample (MSU) if symptomatic, change the catheter, and give antibiotics as per local guidelines.
• Why is the management of UTIs in pregnant women different?

  The stakes are higher due to the association with preterm delivery and intra-uterine growth restriction.
• What should be avoided in the first trimester of pregnancy for UTI treatment?

  Trimethoprim
• What should be avoided in the third trimester of pregnancy for UTI treatment?

  Nitrofurantoin
• What are the signs and symptoms of pyelonephritis?

  Fever

  Rigors

  Vomiting

  Loin pain/tenderness

  Costovertebral pain
• How is pyelonephritis diagnosed and managed?

  Diagnosis is clinical, and management often requires admission and IV antibiotics & correct dehydration
• What investigations are done for pneumonia?

  Obs

  Sputum culture

  Urinary antigens for pneumococcal & legionella antigens

  FBC

  CRP

  U&E

  LFTs

  CXR

  Spirometry

  CT thorax
• What is necrotizing fasciitis?

  Necrotizing fasciitis is a deep infection causing progressive destruction of muscle fascia, often very painful.
• How is necrotizing fasciitis diagnosed?

  Diagnosis is established by visualization during surgery, but CT can often be helpful
• What are the definitions of acute and chronic osteomyelitis?

  Acute osteomyelitis: Acute suppurative infection of the bone progressing over days to weeks.

  Chronic osteomyelitis: Presence of dead bone (sequestrum) and other features...

  • Involucrum (reactive bony encasement of sequestrum)
  • Local bone loss
  • Sinus tracts
• What is the common offender in osteomyelitis?

  Staphylococcus aureus
• How does osteomyelitis get into the bone?

  Haematogenous spread - bacteraemia -> seeding of bacteria into the bone

  Non haematogenous spread - result of spread of infection from surrounding soft tissues into the bone, or via direct inoculation (trauma, bites, surgery)
• What are the signs and symptoms of septic arthritis?

  • Hot, red, painful, swollen joint
  • More common in larger joints or joints with pre-existing arthritis
  • Systemically unwell
• What is sepsis?

  • Sepsis is an inflammatory response to infection.
  • It involves the release of pro-inflammatory cytokines and can lead to tissue hypoxia and organ dysfunction.
• What is the causative agent of tuberculosis?

  Mycobacterium tuberculosis
• What is the treatment of a UTI in pregnant women?


  Abx (avoid trimethoprim (1st trimester) & nitrofurantoin (3rd trimester))

  Confirm eradication (repeat MSU after treatment)
• What is pyelonephritis?


  Kidney infection
• What is an abscess?


  Collection of pus in the dermis or subcutaneous space
• What is the management of necrotizing fasciitis?


  Surgical debridement

  With Abx cover
• What are the signs & symptoms of osteomyelitis?


  Pain

  Swelling

  Erythema/overlying cellulitis

  Ulceration on examination (probing to bone)

  
  

  Often have more systemic symptoms compared to cellulitis
• What are the investigations & diagnosis of osteomyelitis?


  Obs

  Examination of affected area

  FBC

  CRP

  U&E

  Calcium

  Blood cultures

  XR of area (MRI to help confirm -> often used as diagnostic modality)

  Definitive diagnosis = bone biopsy
• What is the management of osteomyelitis?


  IV Abx & debridement (1st line)

  If doesn't work -> amputation
• What is septic arthritis?


  Joint infection
• What are the common causes of septic arthritis?


  Staph aureus

  Streptococci

  Gonorrhoea