Peroral Endoscopic Myotomy (POEM) is a novel, promising endoscopic technique for achalasia because it is safer and more effective than traditional Heller's myotomy. However, the issue of antibiotic prophylaxis in POEM has evoked considerable controversy recently. Therefore, we conduct this study to elucidate the status of POEM-related bacteremia and procalcitonin levels in order to preliminary observe whether antibiotic prophylaxis is needed.

Objective: To elucidate the status of POEM-related bacteremia and procalcitonin levels in order to preliminary observe whether antibiotic prophylaxis is needed.

Interventions: Patients with achalasia diagnosed by symptoms, endoscopy and barium swallow eligible for POEM are randomized to either use antibiotic prophylactically or not.

Main outcome measurements: Blood culture positive incidence; secondary outcomes are procalcitonin levels, C-reactive protein levels, white blood cell counts and so on.

Inclusion Criteria:

• Clinical diagnosis of esophageal achalasia
• Ready to have the treatment as POEM and no contraindication of POEM
• Ability to get informed consent

Exclusion Criteria:

• Patients who had indications for antibiotic prophylaxis as determined by the American Society for Gastrointestinal Endoscopy
• Patients who had received antibiotics for any reason within the previous 7days
• Patients who had possible signs of any infection at the time of the procedure
• Patients who had chronic inflammatory diseases need hormonotherapy : such as rheumatic arthritis or inflammatory bowel diseases.