Name of the Procedure:

Susceptibility studies, antimicrobial agent; microdilution or agar dilution (minimum inhibitory concentration [MIC] or breakpoint), each multi-antimicrobial, per plate

Summary

Susceptibility studies using microdilution or agar dilution methods are laboratory tests designed to determine the effectiveness of antibiotics against bacteria. This procedure measures the minimum inhibitory concentration (MIC) or uses breakpoint methods to identify the concentration at which an antibiotic will inhibit bacterial growth.

Purpose

Susceptibility studies help doctors understand which antibiotics are effective for treating specific bacterial infections. The main goal is to identify the best treatment option for bacterial infections while minimizing antibiotic resistance.

Indications

• Persistent or severe bacterial infections not responding to standard antibiotics
• Infections in immunocompromised patients
• Recurrent infections
• Situations where multi-drug resistant bacteria are suspected

Preparation

• No special preparation typically required for susceptibility studies.
• Collection of a bacterial sample (e.g., blood, urine, tissue) is necessary for testing.

Procedure Description

1. Sample Collection: A bacterial sample is collected from the patient.
2. Sample Preparation: The sample is prepared and cultured in a lab.
3. Microdilution Method:
   • An array of wells containing different concentrations of antibiotics is prepared.
   • The bacterial sample is introduced to each well.
   • Incubation allows for bacterial growth observation.
4. Agar Dilution Method:
   • Agar plates are prepared with varying concentrations of antibiotics.
   • The bacterial sample is spread across the agar surface.
   • Plates are incubated to observe bacterial growth.

The tools include multi-well plates for microdilution, agar plates, and various concentrations of antibiotics. No anesthesia or sedation is needed as this is a lab-based procedure.

Duration

The procedure itself takes a few hours, but results may take 1-2 days depending on the growth rate of the bacteria.

Setting

Performed in a clinical laboratory setting.

Personnel

• Medical Laboratory Technologists
• Microbiologists
• Pathologists

Risks and Complications

As a laboratory procedure, it carries minimal risk to the patient. However, incorrect sample handling could lead to inaccurate results.

Benefits

Determines the most effective antibiotic treatment; results can be available within a few days, leading to faster and more accurate treatment of bacterial infections.

Recovery

No recovery needed as this is a non-invasive lab test.

Alternatives

Other methods such as disk diffusion tests or automated systems for bacterial identification and susceptibility might be used. These may present varying levels of accuracy and turnaround time compared to MIC or breakpoint testing.

Patient Experience

• Typically no direct discomfort or pain since it involves lab work on collected samples.
• Collection of the sample (e.g., blood draw) might cause mild discomfort.

This procedure provides critical information to guide effective treatment plans for bacterial infections, aiding in the successful management and resolution of such conditions.