Soft tissue, bone

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Soft tissue, bone joint infections
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Overview

• Common pyogenic skin infections
• Folliculitis
• Furunculosis
• Carbncles
• Paronychia
• Impetigo
• Cellulitis
• Erysipelas
• Surgical wound infection

• Other soft tissue infections
• Tetanus
• Gas gangrene
• Necrotising facsiitis
• Staphylococcal Scalded Skin Syndrome
• Dermatophyte infections
• Osteomyelitis
• Septic arthritis

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Staphs Streps

• Staphylococcus aureus
• Gram-positive cocci in clusters
• Catalase-postitive
• Coagulase-positive

• Streptococcus pyogenes
• Gram-positive cocci in chains
• Catalase-negative
• Group A beta-haemolytic streptococcus

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Folliculitis

• Infection of hair follicles
• usually pustular folliculitis
• Clinical presentation
• follicle-centred pustules
• e.g. in scalp, groin, beard moustache (sycosis
  barbae)
• Mostly (95) due to Staphylococcus aureus
• Treatment oral flucloxacillin

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Other pyogenic skin infections

• Furunculosis
• form of deep folliculitis.
• Carbuncle
• multiple abscesses in close apposition with
  interconnecting sinuses.
• Acute paronychia
• Skin infection arising from nail
• Treatment
• Oral flucloxacillin

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Impetigo

• Superficial infection
• usually staphylococcal
• but can also involve Streptococcus pyogenes)
• Friable, golden crusts over erythematous skin.
• Treatment
• Topical fucidin or mupirocin 7-10d
• Oral flucloxacillin or erythomycin
• if widespread or unresponsive

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Cellulitis

• Diffuse parenchymal inflammation without necrosis
  or localisation of pus
• Often seen as erythematous halo around a wound
• Commonly caused by S. aureus
• Less common causes S. pyogenes, C. perfringens
• Treatment
• oral pen V flucloaxcillin
• or co-amoxiclav
• If severe may require i-v treatment

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Erysipelas

• Well-demarcated cellulitis with fever and malaise
  
• acute streptococcal infection
• bacteremia common
• upper dermal oedema lifts epidermis except where
  staked down by hair follicles or sweat glands
• leads to the typical peau d'orange appearance
• Treatment penicillin V

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Surgical Wound Infection

• Features
• induration
• fever
• erythema
• leakage of pus
• may have infection in absence of pus (e.g.
  streptococcal cellulitis, gas gangrene, infected
  burns)
• Treatment debridement and antibiotics
  (flucloxacillin benzylpenicillin)

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Tetanus

• Cause neurotoxin from Clostridium tetani
• spores in soil, animal faeces
• introduced into wound, germinate, release
  bacteria, produce a neurotoxin
• selectively blocks inhibitory nerve transmission
  from spinal cord to muscles, muscles go into
  severe spasm
• in developing countries, tetanus frequently
  causes death in neonates when umbilicus infected

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Tetanus

• Clinical features
• begins with mild spasms in the jaw muscles
  (trismus)
• rigidity rapidly develops in the chest, back and
  abdominal muscles and sometimes the laryngeal
  muscles (which then interferes with breathing)
• muscular seizures (tetany) cause sudden,
  powerful, and painful contraction of muscle
  groups.
• fractures and muscle tears can occur

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Tetanus

• Treatment
• intubate,paralyse and sedate in ITU
• without treatment, 1 in 3 adults die, 2 in 3
  neonates
• Prevention
• active immunisation
• in childhood DTP x3
• boosters every ten years as Td shots, especially
  after risky wound
• wound cleaning and debridement
• passive immunisation if tetanus-prone wound in
  unprotected patient

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Gas Gangrene

• infectious disease emergency
• Caused by exotoxin-producing Clostridium
  perfringens
• usually after direct inoculation of contaminated,
  ischaemic wound

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Gas GangreneClinical features

• Myonecrosis, gas production, and sepsis
• rapid onset and progression to toxaemia and shock
  
• crepitus, brawny oedema
• foul-smelling discharge, brown skin
  discoloration, bullae, dead muscle
• infection can advance 1 inch per hour!
• pain out of proportion to physical findings
• Mortality greater than 25

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Gas gangrene

• Diagnosis
• Clinical
• Radiological
• gas within the fascial planes
• Microbiological
• Gram-positive rods in tissues, culture of C.
  perfringens
• Treatment
• fasciotomy, debridement, amputation
• antibiotics (penicillin and metronidazole)
• ?hyperbaric oxygen

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Necrotising Fasciitis

• Similar condition to gas gangrene, but usually
  lacking gas production
• Caused by S. pyogenes and/or S. aureus, often in
  combination with anaerobes
• mortality rate of 30-50
• Treatment
• debridement, amputation
• antibiotics

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Staphylococcal Scalded Skin Syndrome

• seen in infants, young children,
  immuno-compromised
• epidermolytic toxin released into the blood
  stream from localised S. aureus infection
• causes widespread superficial exfoliation

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Dermatophyte Infections (Ringworm)

• Dermatophytes
• fungi that invade dead tissues of the skin or its
  appendages (stratum corneum, nails, hair).
• Trichophyton, Epidermophyton, and Microsporum are
  most commonly involved
• clinical differentiation difficult.
• spread person to person or animal to person.

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Dermatophyte Infections

• Diagnosis
• clinically according to site of infection
• TINEA CORPORIS
• TINEA PEDIS
• Athlete's Foot
• TINEA UNGUIUM
• TINEA CAPITIS
• TINEA CRURIS
• Jock Itch
• TINEA BARBAE
• Barber's Itch

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Dermatophyte Infections

• Diagnosis
• microbiological
• direct microscopic examination of scales
  dissolved in KOH
• by culture of scrapings of lesions

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Dermatophyte Infections

• Treatment
• topical imidazoles or other antifungal
  preparations
• resistant cases or those with widespread
  involvement require oral triazole therapy (NB
  itraconazole interacts with many commonly
  prescribed drugs).

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Bone infection

• Osteomyelitis
• acute (subacute)
• chronic
• specific (eg TB)
• non specific(most common)

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Acute haematogenous OM

• mostly children
• boysgt girls
• history of trauma

• Source of infection
• infected umbilical cord in infants
• boils, tonsilitis, skin abrasions
• in adults UTI, in dwelling arterial line

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Acute OsteomyelitisOrganism

• Gram ve
• Staphylococus aureus
• Streptococcus pyogenes
• Streptococcus pneumoniae
• Gram -ve
• Haemophilus influenzae (50 lt 4 y)
• E .coli
• Pseudomonas aeruginosa,
• Proteus mirabilis

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Acute Osteomyelitis Pathology

• starts at metaphysis
• ?trauma
• vascular stasis
• acute inflammation
• suppuration
• necrosis
• new bone formation
• resolution

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Acute Osteomyelitis Clinical Features

• Adults
• severe pain
• reluctant to move
• Fever, malaise
• commonly thoracolumbar spine--backache
• history of UTI or urological procedure
• Old, diabetic, immunocompromised

• Infants
• failure to thrive, drowsy, irritable
• metaphyseal tenderness
• decrease ROM
• commonest around the knee

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Acute Osteomyelitis Diagnosis

• History and clinical examination
• FBC, ESR, B.C.
• X-ray (normal in the first (10-14) days
• Ultrasound
• Bone Scan Tc 99, Gallium 67
• MRI
• Aspiration

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Chronic Osteomyelitis

• may follow
• acute OM
• operation
• open
• long history (wks, mths)
• pain, limp
• swelling occasionally
• local tenderness
• often mixed infection
• Staph. aureus, E. coli . Strep pyogenes, Proteus
• associated with
• Cavities, dead bone (sequestrum)
• histological picture of chronic inflammation

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Treatment of osteomyelitis

• Flucloxacillin
• or clindamycin if penicillin-allergic
• or vancomycin if resistant Staphylococcus
  epidermidis or MRSA
• combine vancomycin with either fusidic acid or
  rifampicin if prostheses present or if
  life-threatening condition
• Treat acute infection for 46 weeks and chronic
  infection for at least 12 weeks

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Acute Septic Arthritis

• Route of Infection
• direct invasion
• penetrating wound
• intra articular injection
• arthroscopy
• eruption of bone abscess
• haematogenous

• Organisms
• Staphylococus aureus
• Haemophilus influenzae
• Streptococcus pyogenes
• Escherichia coli

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Acute Septic Arthritis

• Infant
• Signs of septicaemia
• Irritability
• resistant to movement
• Child
• Acute pain in single large joint, reluctant to
  move joint
• increase temp. and pulse
• increase tenderness
• Adult
• often involves superficial joint (knee, ankle,
  wrist)

• Investigations
• FBC, WBC, ESR, CRP, BC
• x ray, ultrasound
• Aspiration
• Treatment
• Flucloxacillin fusidic acid
• or clindamycin alone if penicillin-allergic
• or vancomycin if MRSE/MRSA
• combine with fusidic acid or rifampicin if
  prostheses present or if life-threatening
  condition
• Treat for 612 weeks

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Tuberculosis

• Bone And Joint TB
• large joints
• contact with TB
• pain, swelling, loss of weight
• decrease ROM
• Ankylosis, deformity
• Spinal TB
• little pain
• present with abscess or kyphosis

• Diagnosis
• long history
• involvement of single joint
• marked thickening of the synovium
• marked muscle wasting
• periarticular osteoporosis
• ve Mantoux test

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Tuberculosis

• Investigations
• FBC , ESR
• Mantoux
• Xray
• soft tissue swelling
• periarticular osteoporosis
• joint appear washed out
• articular space narrowing
• Joint aspiration
• AFB identified in 10-20
• culture ve in 50

• Treatment
• chemotherapy
• ethambutol, rifampicin and isoniazid 6-12 month
• rest and splintage
• operative drainage rarely necessary