# Applying Machine Learning Techniques to the Audit of Antimicrobial Prophylaxis
## 2 Materials and Methods
### Data Preprocessing
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Attribute** & **Type** & **Remarks** \\ \hline Hospital type & Nominal & Primary: 71 instances. \\  & & Secondary: 258 instances. \\  & & Tertiary: 271 instances \\ \hline Age & Numeric & Mean: 56.2 years \\ \hline Gender & Binary & Female: 297 instances, male: \\  & & 304 instances \\ \hline Patient specialty & Nominal & 29 distinct values \\ \hline Diagnosis & Nominal & 20 distinct values \\ \hline Central vascular catheter in place & Binary & Yes: 75 instances \\  & & No: 526 instances \\ \hline Peripheral vascular catheter in place & Binary & Yes: 477 instances \\  & & No: 124 instances \\ \hline Urinary catheter in place & Binary & Yes: 213 instances \\  & & No: 388 instances \\ \hline Under endotracheal intubation & Binary & Yes: 33 instances \\  & & No: 568 instances \\ \hline Under tracheostomy intubation & Binary & Yes: 9 instances \\  & & No: 592 instances \\ \hline Ventilator used & Binary & Yes: 34 instances \\  & & No: 567 instances \\ \hline Patient has active & Binary & Yes: 6 instances \\ healthcare-associated infection & Binary & No: 595 instances \\ \hline Blood stream infection & Binary & Yes: 0 instances \\  & & No: 601 instances \\ \hline Urinary tract infection & Binary & Yes: 0 instances \\  & & No: 601 instances \\ \hline Pneumonia & Binary & Yes: 2 instances \\  & & No: 599 instances \\ \hline Surgical site infection & Binary & Yes: 3 instances \\  & & No: 598 instances \\ \hline Antimicrobial agents used & Nominal & 15 distinct values \\ \hline Indication of antimicrobial agents & Nominal & 3 distinct values \\ \hline Diagnosis sites for antimicrobial use & Nominal & 16 distinct values \\ \hline Class label attribute & Nominal & 5 distinct values \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Characteristics of dataset. comprehension, the recommendations of guidelines for antimicrobial prophylaxis were briefly stated in Table 2. For details, please refer to the articles that are more complex [7; 18]. If the choice of prophylactic antimicrobial use was in concordance with the recommendations in the practice guidelines, then the compliance with choice of prophylactic antimicrobial agents was determined as \"Yes\"; otherwise, it was determined as \"No\". The duration of prophylactic antimicrobial agents had the following three observed values, i.e., single dose encoded as SP1 (surgical prophylaxis 1), one day encoded as SP2, and more than one day encoded as SP3. If the duration of prophylactic antimicrobial agents was SP1 or SP2, the compliance with duration of prophylactic antimicrobial agents was determined as \"Yes\". If the duration was SP3, the compliance was determined as \"No\". The values of class label attribute, i.e., compliance with guidelines for antimicrobial prophylaxis, were then classified into five types (i.e., A, B, C, D, and E), according to the compliance with both choice and duration of prophylactic antimicrobial agents in Table 3.  
In this study, cefazolin was the most common first-generation cephalospor in used for surgical prophylaxis. The second-generation cephalosporins included cefoxitin mostly, but also cefuroxime. The aminoglycosides included gentamicin and amikacin. Amikacin was used for treatment of infection rather than surgical prophylaxis. The fluoroquinolones included ciprofloxacin and levofloxacin. The \(\beta\)-lactam/\(\beta\)-lactamase combinations included amoxicillin/clavulanic acid, ampicillin/sulphactam, and piperacillin/tazobactam.