Outline

• Introduction• Pyomyositis• Psoas abscess• Nonclostridial myositis• Clostridial myonecrosis• Osteomyelitis• Arthritis

Pyomyositis

- Bacterial infection of skeletal muscle – lower extremities - Abscesses, carbuncles / infected sinuses lying deep- large muscle groups quadriceps/ gluteus - prior muscle injury - infected by transient bacteremia- Tropical pyo. – healthy yng pts.- Temparate pyo. – immunocompromised – older pts.- Staphylococcus common etiology- Presents with fever, pain, edema, bacteremia, sepsis

endocarditis, renal failure, metastasis- Neutrophils important role in defense

Psoas abscess

- Abscess of the psoas muscle usually due to disease of lumbar vertebrae, with the pus descending into the muscle sheath.

- Atypical symptoms - back pain, PUO, groin pain mimicking septic hip, frequency of micturition, lump in abdomen or pain

- Infection - tuberculous or staphylococcal- Drainage & apt antibiotic coverage

Non-clostridial Myositis

- ‘Synergistic necrotizing cellulitis’- Inflam of a voluntary muscle - aggressive soft tissue inf.- Necrosis of muscle tissue- Subcutaneous tissue & skin IIrily involved- Incubation 3 – 14 days, acute onset,- Severe local tenderness, dish-water (foul smelling) pus from surface ulcers- Systemic toxicity severe- Peptstreptococcus, Bacteriodes, entrobacteriaceae

- Mortality – 75%

Differentiation of Common Necrotizing Bacterial Soft Tissue Infection

Gas Gangrene

Clostridial myonecrosis - clostridial inf. of muscle tissue• C. perfringens (90%) C novyi (4 %), C septicum (2 %),C

histolyticum, C fallax, and C bifermentans • acute presentation & fulminant clinical course • occurs - major trauma or surgery or complication of

thermal burns • Bacteremia due to org. from GIT or UTI infection• Rapid progression - delay in treatment fatal• Rapid tissue necrosis-multiple toxins-diff. modes of action• ‘Toxic factor’ – interaction of toxin & infected tissue• Mortality – 15-30%

• Tissue degrading enzymes Tissue degrading enzymes

– lecithinase [lecithinase [ toxin] toxin]– proteolytic enzymesproteolytic enzymes– saccharolytic enzymessaccharolytic enzymes

• Destruction of blood vessels Destruction of blood vessels • Tissue necrosisTissue necrosis• Anaerobic environment created Anaerobic environment created • Organism spreads Organism spreads

PathogenesisPathogenesisC. perfringensC. perfringens

Nagler’s reaction

C. perfringens

Acute osteomyelitis

Chronic osteomyelitis

Hematogenous osteomyelitis

Contiguous spread Osteomyelitis

Diabetic foot infection

Osteomyelitis

• Inflammation of bone caused by a pyogenic organism may be localised or spread to involve marrow, cortex, cancellous tissue & periosteum.

• subacute to chronic infection - improper treatment -severe disability

• Usually bacterial infection

Common sites of infection

- long bones in children

- vertebrae in adults

Long bone anatomy & vasculature

Osteomyelitis

Etiology

Type of Osteomyelitis Common Pathogens

Hematogenous (usually 1 organism)

 

Infant (<1 year) Staph. aureus, Strept. agalactiae, E. coli

Children (1-16 years) Staph. aureus, Strept. pyogenes, H. influenzae

Adults (>16 years) Staph aureus, Coagulase-ve Staph.E. coli, Pseudomonas, Serratia

Contiguous Spread (polymicrobial) : Etiology depends on Iry site of inf.

Staph. aureus, Strept. pyogenes,Enterococcus, Coagulase-ve StaphGram-negatives, Anaerobes

Diabetic foot (polymicrobial)

Staph aureus, Streptococcus & EnterococcusGram-negatives: Proteus mirabilis, Pseudomonas, Anaerobes

Osteomyelitis

ManifestationsLong bone acute infections - chills, fever & malaise. Pain,

localized swelling & redness in infection site & guarding

Vertebral osteomyelitis: localized back pain & tenderness fever is not common

Chronic osteomyelitis: localized pain may come & go Fever rare. 

Osteomyelitis

Arthritis

• An inflammatory condition affecting joints – - infective, - autoimmune- traumatic in origin

• Bacteria, virus & fungi - max. damage bacteria- can lead to permanent damage

• Reactive arth. –inflammation due to inf. at distant site• Suppurative arthritis

Gonococcal & non-gonococcal • Adults – knee, hip, shoulder, ankle, wrist

• Staphylococcus aureus – infectious arth. • Neisseria gonorrhoeae – septic arth. • Reactive arthritis - polyarticular• Viridans streptococci, S. pneumonia, S. agalactiae• Aerobic Gram –ve bacilli• Polymicorbial, anaerobic • Mycobacteria & fungi – monoarticular arth.• Viruses - parvo B19, hepatitis B, rubella, mumps & HIV• Any org. can cause infective arthritis.

EtiologyArthritis

Manifestations

• Fever, pain & impaired motion• Non gonococcal arth. – pain & swelling in single joint• Mono/poly articular arth. - gonococcal arthritis, viral inf.• Gonococcal arth. – presents as

- Tenosynovitis, dermatitis & polyarthritis syndrome - monoarticular

Arthritis