Critical (Panic) Values in Microbiology

Critical/panic values are defined as values that are outside the normal range to a degree that may constitute an immediate health risk to the individual or require immediate action on the part of the ordering physician. Panic values in microbiology encompass the detection of clinically important microorganisms and viruses that require notification, immediate action by the physician, action by hospital personnel and visitors, and notification of governmental agencies (this may differ from country to country).

Certain critical results must be communicated to the clinician immediately. All phone calls made to report critical values are documented in the Laboratory Information System.

Each clinical microbiology laboratory, in consultation with its medical staff, should prepare a list of these so-called panic values.

Figure: Critical Values in Microbiology

Common panic values include

Positive direct examination from sterile body fluids

Cerebrospinal fluid Joint fluid Pleural fluid Pericardial fluid Peritoneal fluid Intraoperative body fluids

Positive CSF Gram stain
Positive CSF antigen detection for pneumococci, Streptococcus agalactiae, Neisseria meningitidis, and Haemophilus influenzae type b (now rare)
Positive cryptococcal antigen test
Positive blood cultures
Blood smear positive for malaria (Plasmodium spp)
AFB smear-positive
Isolation of Mycobacterium tuberculosis
Streptococcus pyogenes (group A Streptococcus) in a surgical wound
Gram stain suggestive of gas gangrene (large box-car shaped gram-positive rods).
Presence of potential B. anthracis or any bioterrorism agent such as Francisella tularensis, Yersinia pestis etc.
Detection of a significant pathogen (e.g., Legionella, Brucella, vancomycin-resistant Staphylococcus aureus)
Positive eye cultures growing Pseudomonas aeruginosa or Bacillus spp.
Positive or suspicious for any pandemic (Influenza or SARS) or Bioterrorism Agents (Smallpox, viral hemorrhagic fever agents)
Isolation of Streptococcus agalactiae from pregnant women (cultures taken at 35–37 wks’ gestation)

References and further readings

Andrea J. Linscott, 2016. 2.1. Collection, Transport, and Manipulation of Clinical Specimens and Initial Laboratory Concerns, *Clinical Microbiology Procedures Handbook,*4th Edition. ASM Press, Washington, DC. doi: 10.1128/9781683670438.CMPH.ch2.1
Tille, P. (2017). Bailey & Scott’s Diagnostic Microbiology (14 edition). Mosby.