The Role of the Microbiology Lab in Antimicrobial Prescription

The microbiology lab is essential to the practice of antimicrobial prescribing. The goal of a microbiologist is to promptly and accurately detect nosocomial pathogens and their antimicrobial resistance patterns.

The microbiology lab’s two main roles are as follows:

1) Optimising antimicrobial therapy/treatment of the patient

• Diagnosis of infection or alternative
• Antibiotic susceptibility results
• Therapeutic drug monitoring
• Biomarkers to guide therapy and facilitate stopping
• Avoiding unnecessary testing
• Assisting in correct microbiological sampling techniques and the timing thereof

2) Providing surveillance/data (monitor the impact of any AMS intervention made)

• Descriptive epidemiology and trend analysis
• Comparisons between institutions and geographical areas
• Assessment of the impact of interventions

The microbiologist consultant should attend daily ICU rounds, and their role should consist of the following:

• Aiding in the interpretation of results
• Assisting in selecting the optimal targeted antibiotic and the correct duration
• Providing cumulative surveillance data on resistant organisms for infection control purposes
• Facilitating infection prevention and control practices

One of the key components of a successful ASP is effective communication with the microbiology team. Not only will this department help the patients get the correct treatment, but they are also vital to the surveillance of antibiotic resistance which will be talked about in step 2.13.

To prescribe the correct treatment for an infection, you need an accurate diagnosis. The video and text below describe how a blood culture is tested in a laboratory.

The process can take up to 3 days, which is quite a long time. This process can be shortened by using new advances and diagnostic techniques.

New Diagnostic Technologies

MALDI-ToF testing is an example of a new technique that rapidly identifies bacteria within a few minutes. It means that a blood culture sample can be tested one day after it is received (the time it takes for growth to occur).

Aside from MALDI-ToF there are other molecular diagnostic tests that can be used, they are able to identify bacteria, and some identify the mechanism of resistance of those bacteria. This can be very useful and can play an important part in AMS and infection control. If a multi-drug resistance organism is detected and reported quickly, infection control specialists and the clinician are able to respond quickly and correctly manage the patient and take the necessary precautions.

Diagnostic Stewardship

Whilst these rapid diagnostic tests are great tools for the diagnosis of infections, some care should be taken. Diagnostic Stewardship is a part of AMS and should be considered in any intervention programme.

It is important to think:

• Right Test
• Right Patient
• Right Time

It is important to remember the impact of getting diagnostics wrong, in particular over-using them.

Please see the additional articles in the see also section for more information on Rapid Diagnostic Technologies.