Pyomyositis is a

bacteria Bacteria (; singular: bacterium) are ubiquitous, mostly free-living organisms often consisting of one biological cell. They constitute a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria were among ...

infection An infection is the invasion of tissues by pathogens, their multiplication, and the reaction of host tissues to the infectious agent and the toxins they produce. An infectious disease, also known as a transmissible disease or communicable dise ...

of the

skeletal muscle Skeletal muscles (commonly referred to as muscles) are organs of the vertebrate muscular system and typically are attached by tendons to bones of a skeleton. The muscle cells of skeletal muscles are much longer than in the other types of muscl ...

s which results in an

abscess An abscess is a collection of pus that has built up within the tissue of the body. Signs and symptoms of abscesses include redness, pain, warmth, and swelling. The swelling may feel fluid-filled when pressed. The area of redness often extends b ...

. Pyomyositis is most common in

tropical The tropics are the regions of Earth surrounding the Equator. They are defined in latitude by the Tropic of Cancer in the Northern Hemisphere at N and the Tropic of Capricorn in the Southern Hemisphere at S. The tropics are also referred to ...

areas but can also occur in

temperate zone In geography, the temperate climates of Earth occur in the middle latitudes (23.5° to 66.5° N/S of Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ranges throughout t ...

Diagnosis

Diagnosis is done via the following manner: * Pus discharge culture and sensitivity * X ray of the part to rule out osteomyelitis * Creatinine phosphokinase (more than 50,000 units) * MRI is useful * Ultrasound guided aspiration

Treatment

The abscesses within the muscle must be drained

surgically Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pat ...

(not all patient require surgery if there is no abscess).

Antibiotics An antibiotic is a type of antimicrobial substance active against bacteria. It is the most important type of antibacterial agent for fighting bacterial infections, and antibiotic medications are widely used in the treatment and prevention o ...

are given for a minimum of three weeks to clear the infection.

Epidemiology

Pyomyositis is most often caused by the bacterium ''

Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...

''. The infection can affect any skeletal muscle, but most often infects the large muscle groups such as the

quadriceps The quadriceps femoris muscle (, also called the quadriceps extensor, quadriceps or quads) is a large muscle group that includes the four prevailing muscles on the front of the thigh. It is the sole extensor muscle of the knee, forming a large ...

gluteal muscles The gluteal muscles, often called glutes are a group of three muscles which make up the gluteal region commonly known as the buttocks: the gluteus maximus, gluteus medius and gluteus minimus. The three muscles originate from the ilium and sac ...

. Pyomyositis is mainly a disease of children and was first described by Scriba in 1885. Most patients are aged 2 to 5 years, but infection may occur in any age group. Infection often follows minor trauma and is more common in the tropics, where it accounts for 4% of all hospital admissions. In temperate countries such as the US, pyomyositis was a rare condition (accounting for 1 in 3000 pediatric admissions), but has become more common since the appearance of the USA300 strain of

MRSA Methicillin-resistant ''Staphylococcus aureus'' (MRSA) is a group of Gram-positive bacteria that are genetically distinct from other strains of ''Staphylococcus aureus''. MRSA is responsible for several difficult-to-treat infections in humans. ...

. Gonococcal pyomyositis is a rare infection caused by ''

Neisseria gonorrhoeae ''Neisseria gonorrhoeae'', also known as ''gonococcus'' (singular), or ''gonococci'' (plural), is a species of Gram-negative diplococci bacteria isolated by Albert Ludwig Sigesmund Neisser, Albert Neisser in 1879. It causes the sexually transmit ...

''.

Additional images

File:CT pyomyositis.jpg, CT with IV contrast showing enlargement and heterogeneous hypodensity in the right pectoralis major muscle. A focal abscess collection with gas within it is present medially. There are enlarged axillary lymph nodes and some extension into the right hemithorax. Note the soft tissue and phlegmon surrounding the right internal mammary artery and vein. The patient was HIV+ and the pyomyositis is believed to be due to direct inoculation of the muscle related to parenteral drug abuse. The patient admitted to being a "pocket shooter" File:Tropical pyomyositis CT.JPG, CT exam showing a multiloculated fluid collection in the left gluteus minimus muscle found to be a staph aureus pyomyositis in a 12-year-old healthy boy. File:Axial T1 FS Post Gad tropical pyomyositis.JPG, Axial T1 weighted fat suppressed post IV gadolinium contrast enhanced MRI image showing a mutliloculated bacterial abscess in the left gluteal muscle which grew ''Staphylococcus aureus'' (methicillin sensitive) thought to be due to tropical pyomyositis. File:Cor post gad MRI Tropical pyomyositis.JPG, Coronal fat suppressed post contrast image showing a multiloculated bacterial abscess in the left gluteus minimus muscle due to tropical pyomyositis. File:Cor T2 MRI tropical pyomyositis.JPG, Coronal T2 weighted fat suppressed image showing a multiloculated fluid collection in the left gluteal musculature due to tropical pyomositis in a 12-year-old boy.

References

*Maravelas R, Melgar TA, Vos D, Lima N, Sadarangani S (2020). "Pyomyositis in the United States 2002-2014". J Infect. 80(5):497-503. doi:10.1016/j.jinf.2020.02.005. .

External links

{{Bacterial cutaneous infections Bacterial diseases Bacterium-related cutaneous conditions Muscular disorders Inflammations