To compare the clinical response (efficacy) and the safety of the tigecycline once daily regimen versus the standard regimen (twice daily regimen). Clinical response was categorized as a cure, failure of treatment, or indeterminate outcome.24 Treatment success (Cure): defined as resolution of signs/symptoms of infection, microbiological cure (negative cultures after tigecycline use), improvement of infection markers (leukocytic count, C reactive protein, and procalcitonin).

Treatment failure: defined as persistence of signs/symptoms of infection despite antimicrobial therapy, deterioration of infection markers (leukocytic count, C reactive protein, and Procalcitonin).

Indeterminate response: subjects who do not have an outcome determination for reasons unrelated to the study drug or infection (e.g., loss to follow-up, withdrawal of consent, etc.) Safety will be assessed by the incidence of adverse events especially which leads to treatment discontinuation.36

Inclusion Criteria:

• Age 18 years or older.
• Both males and females.
• Diagnosis of infection has been established and tigecycline use is indicated (intra-abdominal, community-acquired pneumonia, skin Infections) or based on genetic testing and microbiological cultures (MDR Acinetobacter, MDR Stenotrophomonas, MDR Enterobacteriaceae, etc.)

Exclusion Criteria:

• Pregnancy and lactation.
• Bloodstream infections (BSI) and urinary tract infections (UTIs).
• Refusal of attending staff or patient, or family.
• Contraindications to tigecycline, such as hypersensitivity and allergy.
• Patients receiving ≤ 1 day of tigecycline (insufficient length of therapy).
• Patients who have acute physiology and chronic health evaluation (APACHE 2) score of more than 35 (high risk of mortality).
• Do not resuscitate/do not intubate (DNR, DNI) patients.