The main goal of treatment is to remove the cause of the phlegmonous process in order to achieve effective treatment and prevention of recidives.

If the patient's condition is mild and signs of inflammatory process are present without signs of infiltrates, then conservative treatment with antibiotics is sufficient.

If the patient's condition is severe, however, immediate operation is usually necessary with application of drainage system. All of these are done under general anaesthesia. During operation, the cavity or place of phlegmonous process are washed with antiseptic, antibiotic solutions and proteolyic ferments.

In post-operative period, patients are treated with intravenous antibiotics, haemosorbtion, vitaminotherapy. Additionally, the use of i/v or i/m antistaphylococci γ-globulin or anatoxin can be taken as immunotherapy.

During operation of phlegmon dissection at any location, it is important:

1. to avoid spreading of pus during operation;

2. to take into account the cosmetic value of the operating site, especially when treating phlegmmonous process of the face; and

3. to avoid damaging nerves.

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.

Predicts mortality risk in pancreatitis with fewer variables than Ranson's criteria. Data should be taken from the first 24 hours of the patient's evaluation.

- BUN >25 mg/dL (8.9 mmol/L)

- Abnormal mental status with a Glasgow coma score <15

- Evidence of SIRS (systemic inflammatory response syndrome)

- Patient age >60 years old

- Imaging study reveals pleural effusion

Patients with a score of zero had a mortality of less than one percent, whereas patients with a score of five had a mortality rate of 22 percent. In the validation cohort, the BISAP score had similar test performance characteristics for predicting mortality as the APACHE II score. As is a problem with many of the other scoring systems, the BISAP has not been validated for predicting outcomes such as length of hospital stay, need for ICU care, or need for intervention.

In predicting the prognosis, there are several scoring indices that have been used as predictors of survival. Two such scoring systems are the Ranson criteria and APACHE II (Acute Physiology and Chronic Health Evaluation) indices. Most, but not all studies report that the Apache score may be more accurate. In the negative study of the APACHE-II, the APACHE-II 24-hour score was used rather than the 48-hour score. In addition, all patients in the study received an ultrasound twice which may have influenced allocation of co-interventions. Regardless, only the APACHE-II can be fully calculated upon admission. As the APACHE-II is more cumbersome to calculate, presumably patients whose only laboratory abnormality is an elevated lipase or amylase do not need assessment with the APACHE-II; however, this approach is not studied. The APACHE-II score can be calculated at www.sfar.org.

Practice guidelines state:

While there is no laboratory test specific for appendicitis, a complete blood count (CBC) is done to check for signs of infection. Although 70–90 percent of people with appendicitis may have an elevated white blood cell (WBC) count, there are many other abdominal and pelvic conditions that can cause the WBC count to be elevated. Due to its low sensitivity and specificity, on its own, WBC is not seen as a good indicator of appendicitis.

A urinalysis generally does not show infection, but it is important for determining pregnancy status, especially the possibility of an ectopic pregnancy in women of childbearing age. The urinalysis is also important for ruling out a urinary tract infection as the cause of abdominal pain. The presence of more than 20 WBC per high-power field in the urine is more suggestive of a urinary tract disorder.

MRI use has become increasingly common for diagnosis of appendicitis in children and pregnant patients due to the radiation dosage that, while of nearly negligible risk in healthy adults, can be harmful to children or the developing fetus. In pregnancy, it has been found to be more useful during the second and third trimester, particularly as the enlargening uterus displaces the appendix, making it difficult to find by ultrasound. The periappendiceal stranding that is reflected on CT by fat stranding on MRI appears as increased fluid signal on T2 weighted sequences. First trimester pregnancies are usually not candidates for MRI, as the fetus is still undergoing organogenesis, and there are no long-term studies to date regarding its potential risks or side effects.

As the infection is usually transmitted into humans through animal bites, antibiotics usually treat the infection, but medical attention should be sought if the wound is severely swelling. Pasteurellosis is usually treated with high-dose penicillin if severe. Either tetracycline or chloramphenicol provides an alternative in beta-lactam-intolerant patients. However, it is most important to treat the wound.

Diagnosis is made with isolation of "Pasteurella multocida" in a normally sterile site (blood, pus, or cerebrospinal fluid).