Case 12: osteomyelitis, septic arthritis, pneumonia Flashcards
Assessing diabetic ulcers
‘Probe to bone test’ a sterile metal instrument is used to probe the ulcer, with the detection of a hard and gritty surface suggesting osteomyelitis. This may guide the need for further investigation such as imaging or biopsy.
Osteomyelitis- investigations
- Blood tests: raised WCC, CRP and PV (Plasma viscosity), Blood cultures positive in half of cases
- X-ray: soft tissue swelling, osteopaenia, bone destruction, periosteal reaction, endosteal scalloping and new bone apposition. Often normal for the first two weeks of infection.
- MRI: first line, initially bone marrow oedema
- High resolution CT
- Bone biopsy: to identify causative organism, not done if radiological evidence (gold standard)
Osteomyelitis antibiotics
- Flucloxacillin (clindamycin if penicillin allergic), possibly with fusidic acid or rifampicin for the first two weeks
- If MRSA: vancomycin or teicoplanin
- If the affected bone is completely removed a short duration of antibiotics may be sufficient
- Otherwise at least 6 weeks of treatment, usually parental via PICC is needed
- Chronic osteomyelitis may require 3 months of antibiotics
Osteomyelitis surgery
- Any infected necrotic bone should be removed
- Urgent surgical debridement: necrotising soft tissue infection, secondary systemic infection from osteomyelitis. Drain pus and remove sequestra (dead bone)
- Post surgery: soft tissue envelope can help healing
- Orthopaedic hardware: seek secondary opinion
- Prosthetic joins may need revision surgery
Septic arthritis: clinical features
- Red, hot, swollen joint.
- Painful and reduced range of movement- in both active and passive movement
- Will cause Tachycardia and a fever.
- Usually single join affected
- Can have intraarticular effusion
- Knee most common
How elderly patients present with septic arthritis
- Elderly patients tend to present as afebrile and systemically well.
- WCC may be normal in 50%.
- More likely to present with non-specific symptoms such as worsening cognitive impairment, confusion and more frequent falls.
Septic arthritis- medical emergency
Regard a hot, swollen, acutely painful joint with restriction of movement as septic arthritis until proven otherwise.
Risk factors for septic arthritis
- RA and SLE
- Diabetes
- Immunosuppression
- Kidney failure
- Joint replacement
How may gonococcal arthritis present
- May present as either:
- Septic arthritis (typically milder than S aureus) OR
- Arthritis dermatitis syndrome (triad of rash, tenosynovitis and migratory polyarthritis affecting upper limbs)typically follows mucosal infection
Septic arthritis: how pathogens are spread
- Direct injury: injury to a joint with skin break or infected neighbouring bone (infection spreads into joint)
- Haematogenous: infection in other organs and spreads to joint via blood stream. Examples: abscess and wounds, Septicaemia, Gonorrhoea
Bacterial toxins destroy cartilage and cause progressive joint destruction
Septic arthritis: pathogensand risk factors
- Neisseria gonorrhoea: most common in young sexually active individuals
- Staph aureus: most common cause in adults
Risk factors
- Prosthetic joints
- Invasive joint procedures i.e. steroid injections, arthroscopy
- IV drug use
- Immunosuppression, chronic skin cancer
Septic arthritis: risk factors
- Established joint disease
- Recent joint injection/sugery
- Immunosuppression- diabetes, alcoholism
- IVDU
- Prosthetic joints
- UTI, indwelling catheter, recent abdominal surgery
Diagnosing septic arthritis
- Blood cultures (may be negative)
- Synovial fluid analysis (joint aspirate)
- Gram stain will show inflammatory effusion with neutrophil predominance plus or minus gram negative diplococci
- Culture & sensitivity testing
- NAAT PCR (if available and validated for synovial fluids)
Septic arthritis: Investigations
- Bedside: Obs, urine dip, ECG, CXR (for haematogenous spread infection)
- Bloods: FBC, U&E, LFT, CRP, Lactate, Coag, culture, ESR
- Imaging: X-ray is not diagnostic is useful to see baseline joint condition. May see increased synovial fluid or bone destruction
- Joint arthrocentesis/aspiration: for synovial fluid analysis, gram staining and culture prior to antibiotics
- WCC >100,000 suggests diagnosis is highly likely
Septic arthritis: management
- IV ABX: for 4-6 weeks (initially IV for 2 weeks)
- Analgesia
- May require joint washout with surgeons
Septic arthritis: Arthrocentesis
- Contraindications: overlying skin infection, anti-coagulation, low platelets
- Aspirate to dryness
- Look at colour, viscosity and clarity of the joint aspirate
- Send for: gram stain, WCC, microscopy, culture, polarising microscopy (for crystals)
- Negative synovial culture does not exclude septic arthritis
- Once done give IV antibiotics, immobilise the joint and analgesia
Aspirate in septic arthritis
The aspirate will look thick, yellow and turbid. It will return as ‘positively birefringent rhomboid shaped crystals under polarised light microscopy.’
The Kocher criteria for the diagnosis of septic arthritis
- fever>38.5 degrees C
- non-weight bearing
- raised ESR
- raised WCC
Management of septic arthritis
- Septic six protocol
- Admit to hospital for IV antibiotics and joint drainage
- Infection in aprosthetic jointwarrants urgent referral to orthopaedics, and should be managed in theatre: This includes surgical arthrocentesis and washout.
- Infection in a native joint can be treated with joint aspiration and empirical antibiotic management
- Prosthetic joint surgery: DAIR procedure (Debridement, Antibiotics and Implant Retention)
Antibiotics in septic arthritis
- Flucloxacillin 2g QD
- gonococcal arthritis: ceftriaxone or Cefotaxime
- Antibiotics are typically continued IV for 2 weeks, before switching to PO if the patient is improving.
- Joint aspirate before starting antibiotics
- Start antibiotics oncecultures are taken
Septic arthritis complications: complications
- Joint damage
- Osteomyelitis: if suspected MRI
- Sepsis
Chronic periprosthetic joint infection
- Delayed months - years
- Biofilm maturity: mature
- Clinical features: chronic pain, loosening of the prosthesis, sinus tract (fistula)
- Organism: Coagulase negative staph
- Treatment: complex removal of prosthesis. Exchange in 1, 2 or 3 stage
Types of URTI
- Rhinitis/ Rhino-sinusitis: runny nose, congestion, tender sinuses
- Pharyngitis/ tonsillitis: sore throat, tonsillar discharge..
- Epiglottitis: stridor, drooling, loss of voice
- Laryngitis/ laryngotracheitis: hoarse voice, cough
- Otitis media (AOM) and Otitis externa (OE)
EBV- glandular fever
- Triad of: sore throat, pyrexia and lymphadenopathy
- Can also get Splenomegaly, Hepatitis, Haemolytic anaemia and jaundice
- Can get a Maculopapular rash with Amoxicillin
- Diagnosed with monospot test
Causes of URTI
- Viruses: Rhinovirus, Coronavirus, Influenza, RSV, adenovirus, EBV
- Bacteria: Group A streptocous (Tonsilitis), S.pneumonia, HIB
- Other: Candida, Toxoplasma
- Vaccinated againsy: HIB, Corynebacterium diphtheriae, Bordatella pertusis
- Upper respiratory tract ends at the Larynx
- Ranges from common cold to Epiglottitis
Modified Centor score: for tonsilitis
- Tender/swollen anterior cervical nodes (+1)
- Cough absent (+1)
- Exudate or tonsil swelling (+1)
- Temperature >38 (+1)
- Prescribe antibiotics if score >3 (Phenoxymethylpenicillin- erythromycin if penicillin allergic)
Tonsilitis
- Complication: Peri-tonsilar abscess (have to drain)
- Acute onset of sore throat, fever, dysphagia
Diptheria
- Children receive vaccine in first year of life
- Associated with travel or immigrants
- Grey plaque in the mouth
- Fever, sore throat, swollen neck
- Bulls neck appearance or skin lesions
- Management: antibiotics, anti-toxin, notifiable disease
Epiglottitis
- Particularly affects children
- Caused by Haemophilia Influenza B (HIB)
- Fever, sore throat, drooling , stridor
- Do not agitate the patient (bloods, oral cavity examination, keep child with their carer if you can)
- Airway support vital- ENT/anaesthetics
- Antibiotics
Bronchitis
- Common
- Characterised by bronchial inflammation with viral infection
- Presents with cough, sputum, and evidence of upper airway infection
- Absence of abnormalities on CXR distinguishes acute bronchitis from pneumonia
- Usually caused by viral infection, usually not dangerous, generally gets better without antibiotics, seldom needs admission to hospital
- Resolves within 3 weeks
Pneumonia history
Pleuritic chest pain, productive cough, fever, SOB, Possible confusion
Pneumonia risk factors
- Aged under 5 or over 65-years-old
- Smoking cigarettes
- Recent viral respiratory tract infection
- Chronic respiratory diseases:e.g. cystic fibrosis and COPD
- Immunosuppression:e.g. cytotoxic drug therapy and HIV
- Patients at risk of aspiration:e.g. those with neurological diseases such as Parkinson’s disease or those with oesophageal obstruction
- IV drug users
- Other non-respiratory co-morbidities:e.g. diabetes and cardiovascular disease
Pneumonia examination
- Tachypnoea, tachycardia, hypoxia
- Fever, confusion
- Decreased chest expansion on affected side
- Dullness to percuss on affected side
- Bronchial breath sounds on affected side
- Crackles on affected side
- Increased vocal resonance on affected side
Pneumonia symptoms
- Pleuritic pain (unilateral)
- Dry cough, then purulent
- Shallow rapid breathing
- Possible confusion
- Loss of appetite, low energy and fatigue
- Probable preceding viral infection
- Rapidly more ill, temp up to 39.5 degrees
Causes of viral and community pneumonia
Causes of community acquired pneumoniae: S.pneumoniae, H.influenzae (COPD)
Viral pneumonia: Influenza virus (most common viral), RSV (common in infants and elderly)
Causes of hospital acquired pneumonia
E.coli, S.aureus, Klebsiella pneumoniae (alcoholics and impaired swallow), Pseudomonas aeruginosa (cystic fibrosis or immunocompromised)
Community vs Hospital acquired pneumonia
- hospital-acquired pneumonia (HAP): pneumonia that occurs ≥ 48 hours after admission
- ventilator-associated pneumonia (VAP): pneumonia that develops ≥48 hours after endotracheal intubation
Atypical pneumonias
- symptoms may be subacute or less severe hence the term ‘walking pneumonia’
- absence of lobar consolidation on chest x-ray
- not detectable on Gram stain
- lack of response to penicillin antibiotics
- Examples: Legionella pneumonia, Mycoplasma pneumonia
Pneumonia investigations
- Bedside: Obs
- Bloods: FBC, U&Es, CRP, blood/sputum culture
- Imaging: CXR - look for areas of opacification (consolidation)
- CURB65 score
CURB-65 scoring system: mortality rate in hospital
- Confusion (AMTS<=8)
- Raised blood urea nitrogen >=7 mmol/L
- Respiratory rate >30
- Blood pressure <60 diastolic or <90 systolic
- Age >=65
- Score 0-1 = low risk
- Score 2 = moderate risk
- Score 3-5 = high risk
CRB65 score (mortality risk in GP)
- Confusion [AMTS 8 or less]
- Raised respiratory rate [30 or more]
- Low BP [DBP <60mmHg or SBP <90mmHg]
- Aged 65 or more
- Stratified for risk or death:
- 0: low risk [<1% mortality]
- 1 or 2: intermediate risk [1-10% mortality
- 3 or 4: high risk [>10% mortality
Atypical pneumonias
Legionella, often found in air conditioning units at hotels. Tested from urine sample. May test for HIV at same time.
Pneumonia management CAP
- Maintain airway, support breathing, high flow O2 if needed
- Antibiotics asap (adjust after microbiology results) PO:
- Low risk patient: Amoxicillin (or doxycycline if pen allergic)
- Moderate risk patient: Amoxicillin + Clarythromycin
- High risk patient: Co-amoxiclav + Clarythromycin
How to manage pneumonia of differing severity
- Low risk: home based care, antibiotics for 5 days
- Medium or high severity: hospitalisation with 5-7 days of antibiotics
- If CURB-65 score 4-5 consider ICU
HAP
- Organisms similar to CAP but in addition S.aureus and gram negative
- Usually bacterial
- Significant cause of death in ICU and lengthens hospital stays
Pneumonia management HAP
- Maintain airway, support breathing, high flow O2 if needed
- Antibiotics asap (adjust after microbiology results):
- Low/moderate risk patient: Co-amoxiclav PO
- High risk patient/severe infection: Piperacillin or ceftazidine or cetriaxone IV
6 weeks after the initial pneumonia presentation you do a chest x-ray to make sure there isn’t a tumour hidden by the consolidation
Discharge after pneumonia
NICE recommend that patients are not routinely discharged if in the past 24 hours they have had 2 or more of the following findings:
- temperature higher than 37.5°C
- respiratory rate 24 breaths per minute or more
- heart rate over 100 beats per minute
- systolic blood pressure 90 mmHg or less
- oxygen saturation under 90% on room air
- abnormal mental status
- inability to eat without assistance.
Natural history of pneumonia
- 1 week – fever resolved
- 4 weeks – chest pain & sputum production substantially reduced
- 6 weeks – cough & breathlessness substantially reduced
- 3 months – most resolved but fatigue may be present
- 6 months - most people back to normal
Brain abscess
- A focal, infectious, intra-cerebral collection of pus, encapsulated within a well-vascularised wall
- Originate from contiguous spread of infection from sinusitis, otitis media, or dental infections; haematogenous spread from distant sources (e.g., endocarditis, pulmonary infections); or direct inoculation from trauma or neurosurgical procedures.
- Risk factors include immunocompromised states, congenital heart disease (right-to-left shunts), chronic otitis and sinusitis, and intravenous drug use.
Progress of brain abscess
- early/initial cerebritis (1-3 days)
- late cerebritis (4-9 days)
- early capsule formation (10-13 days)
- late capsule formation (14 days onwards)
