Soft tissue, bone joint infections

1. Soft tissue, bone & joint infections

2. 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

3. 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

4. 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

5. 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

6. 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

7. 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

8. 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 

9. 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)

10. 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

11. 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

12. 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

13. Gas Gangrene infectious disease emergency Caused by exotoxin-producing Clostridium perfringens usually after direct inoculation of contaminated, ischaemic wound

14. 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%

15. 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

16. 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

17. 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

18. 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.

19. 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

20. Dermatophyte Infections Diagnosis microbiological direct microscopic examination of scales dissolved in KOH by culture of scrapings of lesions

21. 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).

22. Bone infection Osteomyelitis acute (subacute) chronic specific (eg TB) non specific(most common)

23. Acute haematogenous OM mostly children boys> girls history of trauma Source of infection infected umbilical cord in infants boils, tonsilitis, skin abrasions in adults UTI, in dwelling arterial line

24. Acute OsteomyelitisOrganism Gram +ve Staphylococus aureus Streptococcus pyogenes Streptococcus pneumoniae Gram -ve Haemophilus influenzae (50% < 4 y) E .coli Pseudomonas aeruginosa, Proteus mirabilis

25. Acute Osteomyelitis Pathology starts at metaphysis ?trauma vascular stasis acute inflammation suppuration necrosis new bone formation resolution

26. 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

27. 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

28. 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

29. 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 4�6 weeks and chronic infection for at least 12 weeks

30. 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

31. 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 6�12 weeks

32. 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

33. 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