Epidemiology of Antimicrobial-use and Antimicrobial-resistant Infections in Four Hospitals in Thailand

The main goal of this retrospective observational study is to understand how stepping down antibiotic treatment (called antibiotic de-escalation) affects patients who receive it compared to those who don't after received a short-course (≤7 days) of parenteral antibiotics. The investigators will use past medical records from four public referral hospitals in Thailand from the year 2019 to 2024. The investigators will firstly evaluate which types of patients are more likely to receive antibiotic de-escalation. Then, the investigators will estimate the impact of antibiotic de-escalation, while taking those differences into account. This way, it will help us understand the impact of antibiotic de-escalation in real-world clinical practice. The investigators also aim to assess how accurate automated outbreak detection systems are at detecting outbreaks, evaluate patterns of antimicrobial use and antimicrobial-resistant infections, and develop new indicators for antimicrobial stewardship that are applicable for local and national actions in low and middle-income countries.

For primary objectives Inclusion Criteria * All age and gender * Admitted to four collaborating hospitals from 1 Jan 2019 to 31 Dec 2024 * Received a parenteral antibiotic for at least four consecutive days * Were still hospitalized on day 8 after starting a parenteral antibiotic Exclusion Criteria * Admitted as day admissions to four collaborating hospitals from 1 Jan 2019 to 31 Dec 2024 * Had a clinical specimen collected within 2 calendar days of starting a parenteral antibiotic culture positive for an antimicrobial-resistant organism or Staphylococcus aureus Antimicrobial-resistant (AMR) organism is defined as an organism that is resistant to Access and Low Watch antibiotics, and if the organism is the cause of infection, the recommended antimicrobial therapy involves the use of Medium Watch, High Watch or Reserve antibiotics. The common organisms include methicillin-resistant S. aureus, methicillin-resistant coagulase-negative Staphylococcus spp., ampicillin-resistant Enterococcus spp., vancomycin-resistant Enterococcus spp., 3rd-generation cephalosporin-resistant Gram-negative bacterium and carbapenem-resistant Gram-negative bacterium. The definition of organism includes organisms frequently associated with contamination including coagulase-negative staphylococci, viridans group streptococci, Corynebacterium spp., Bacillus spp., Diptheroid spp., Micrococcus spp. and Propionibacterium spp.. All types of specimens are included (e.g. sputum and tracheal suction). We excluded such patients because the study has no clinical data to differentiate whether the isolated AMR organisms are causing infections or represent colonization. For secondary objectives Inclusion Criteria: * All age and gender * Admitted to four collaborating hospitals from 1 Jan 2019 to 31 Dec 2024 Exclusion Criteria: • Admitted as day admissions to four collaborating hospitals from 1 Jan 2019 to 31 Dec 2024