Pott's disease is a tuberculous disease of the vertebrae marked by stiffness of the vertebral column, pain on motion, tenderness on pressure, prominence of certain vertebral spines, and occasionally abdominal pain, abscess formation, and paralysis.

Ankylosing spondylitis is an inflammatory disease involving the spine and sacroiliac joints, and is therefore also a form of spondylarthritis.

A combination of spondylitis and inflammation of the intervertebral disc space is termed a spondylodiscitis.

Spondylitis is one of the most common causes of back and neck pain, and results from inflammation of the vertebral joints. The condition is often not detected until it has fully developed and is causing pain. The pain is usually concentrated around the cervical region of the neck, shoulder and lower spine, with downward-moving stinging pain. Types of spondylitis include: cervical spondylitis – which affects the cervical spine, causing pain to spread the back of the neck; lumbar spondylitis – which causes pain in the lumbar region; and ankylosing spondylitis- which is primarily a disease that affects the sacroiliac joints, causing stiffness in the neck, jaw, shoulders, hips and knees.

Spondylitis is an inflammation of the vertebra. It is a form of spondylopathy. In many cases spondylitis involves one or more vertebral joints as well, which itself is called spondylarthritis.

Symptoms include severe back pain, leading to lack of mobility. Some very young children may refuse to walk and arching of the back is possible. In post-operative situations, the symptoms occur within a week and result in severe low back pain or neck pain (depending on the surgical location). If untreated, the discitis may resolve on its own, causing spontaneous fusion of the intervertebral disc space, cause a chronic low grade infection, or progress to osteomyelitis and possibly even an epidural abscess. In case of concomitant inflammation of one or more vertebrae (in such cases usually the areas adjacent to the intervertebral disc spaces) the condition is called spondylodiscitis.

Spondylodiscitis is a combination of discitis (inflammation of one or more intervertebral disc spaces) and spondylitis (inflammation of one or more vertebrae), the latter generally involving the areas adjacent to the intervertebral disc space.

Spondylodiscitis is the most common complication of sepsis or local infection, usually in the form of an abscess. The main causative organisms are staphylococci and Mycobacterium tuberculosis, but potential organisms include a large number of bacteria, fungi, zoonoses. Spondylodiscitis frequently develops in immunocompromised individuals, such as by a cancer, infection, or by immunosuppressive drugs used for organ transplantations.

Discitis or diskitis is an infection in the intervertebral disc space that affects different age groups. In adults it can lead to severe consequences such as sepsis or epidural abscess but can also spontaneously resolve, especially in children under 8 years of age. Discitis occurs post surgically in approximately 1-2 percent of patients after spinal surgery.

Phlegmon is a spreading diffuse inflammatory process with formation of purulent exudate (the suppuration of pus). This is the result of acute purulent inflammation which may be related to bacterial infection; however, the term 'phlegmon' (from Greek 'phlegmone', inflammation) mostly refers to a walled-off inflammatory mass without bacterial infection, one that may be palpable on physical examination.

An example would be phlegmon of diverticulitis. In this case a patient would present to the emergency department with left lower-quadrant abdominal tenderness, and the diagnosis of sigmoid diverticulitis would be high on the differential diagnosis, yet the best test to confirm it would be CT scan.

Another example, phlegmon affecting the spine, is known as spondylodiscitis and is associated with endplate destruction and loss of disc height. In adults, the bone marrow is affected first, while in children, the disease starts in the disc itself and spreads rapidly to the adjacent vertebral bodies. Phlegmon in the spine can be a diffuse enhancement, or localized abscess, (peripheral enhancement) in the epidural, subligamentous or paraspinous spaces. Under MRI examination, phlegmon will show dark with T1, and high signal (bright) with T2.

Systemic features of infection such as increased body temperature (up to 38-40 °C), general fatigue, chills, sweatings, headache, loss of appetite).

Inflammatory signs – dolor (localized pain), calor (increase local tissue temperature), rubor (skin redness/hyperemia), tumor (either clear or non-clear bordered tissue swelling), functio laesa (diminish affected function).

NB: severity of patient condition with phlegmons is directly proportional to the degree of intoxication level i.e. the more severe the condition, the higher the degree of intoxication level.

A noninfectious occurrence of phlegmon can be found in the acute pancreatitis of Systemic Lupus Erythematosus. The immunosuppressive aspects of this disease and the immunosuppressive medications used to treat it blunt each of the signs of infection.

The symptoms are like those associated with many other febrile diseases, but with emphasis on muscular pain and night sweats. The duration of the disease can vary from a few weeks to many months or even years.

In the first stage of the disease, sepsis occurs and leads to the classic triad of undulant fevers, sweating (often with characteristic foul moldy smell sometimes likened to wet hay), and migratory arthralgia and myalgia (joint and muscle pain). Blood tests characteristically reveal a low number of white blood cells and red blood cells, show some elevation of liver enzymes such as aspartate aminotransferase (AST) and alanine aminotransferase (ALT), and demonstrate positive Bengal Rose and Huddleston reactions. Gastrointestinal symptoms occur in 70% of cases and include nausea, vomiting, decreased appetite, unintentional weight loss, abdominal pain, constipation, diarrhea, an enlarged liver, liver inflammation, liver abscess, and an enlarged spleen.

This complex is, at least in Portugal, Israel, and Jordan, known as Malta fever. During episodes of Malta fever, melitococcemia (presence of brucellae in blood) can usually be demonstrated by means of blood culture in tryptose medium or Albini medium. If untreated, the disease can give origin to focalizations or become chronic. The focalizations of brucellosis occur usually in bones and joints and spondylodiscitis of the lumbar spine accompanied by sacroiliitis is very characteristic of this disease. Orchitis is also common in men.

Diagnosis of brucellosis relies on:

1. Demonstration of the agent: blood cultures in tryptose broth, bone marrow cultures. The growth of brucellae is extremely slow (they can take up to two months to grow) and the culture poses a risk to laboratory personnel due to high infectivity of brucellae.

2. Demonstration of antibodies against the agent either with the classic Huddleson, Wright, and/or Bengal Rose reactions, either with ELISA or the 2-mercaptoethanol assay for IgM antibodies associated with chronic disease

3. Histologic evidence of granulomatous hepatitis on hepatic biopsy

4. Radiologic alterations in infected vertebrae: the Pedro Pons sign (preferential erosion of the anterosuperior corner of lumbar vertebrae) and marked osteophytosis are suspicious of brucellic spondylitis.

The consequences of "Brucella" infection are highly variable and may include arthritis, spondylitis, thrombocytopenia, meningitis, uveitis, optic neuritis, endocarditis, and various neurological disorders collectively known as neurobrucellosis.

Brucellosis is a highly contagious zoonosis caused by ingestion of unpasteurized milk or undercooked meat from infected animals, or close contact with their secretions.

"Brucella" species are small, gram-negative, nonmotile, nonspore-forming, rod-shaped (coccobacilli) bacteria. They function as facultative intracellular parasites, causing chronic disease, which usually persists for life. Four species infect humans: "B. abortus", "B. canis", "B. melitensis", and "B. suis". "B. abortus" is less virulent than "B. melitensis" and is primarily a disease of cattle. "B. canis" affects dogs. "B. melitensis" is the most virulent and invasive species; it usually infects goats and occasionally sheep. "B. suis" is of intermediate virulence and chiefly infects pigs. Symptoms include profuse sweating and joint and muscle pain. Brucellosis has been recognized in animals and humans since the 20th century.