Overview
The chain of infection describes the sequence required for a pathogen to spread from a reservoir to a susceptible host. Laboratory specimen handling can either interrupt or perpetuate links in that chain.
Classification
| Link | Definition | Micro lab example |
|---|---|---|
| Infectious agent | Pathogen capable of disease | Organism in a clinical specimen |
| Reservoir | Place agent persists | Patient, environment, leaking cup |
| Portal of exit | Leave reservoir | Stool, sputum, wound drainage, blood |
| Transmission | Travel to next host | Contact, droplet, airborne, vehicle |
| Portal of entry | Enter new host | Mucosa, broken skin, inhalation, inoculation |
| Susceptible host | At-risk recipient | Patients, visitors, laboratory staff |
Morphologic Features
Conceptual infection-prevention model, not morphologic.
Laboratory Characteristics
- Secondary containment / bagging
- Rejection of leaking containers
- Surface disinfection schedules
- Segregation of waste streams
Reference Intervals
Not applicable. Precaution categories and acceptance rules are institutional and method-specific.
Clinical and Laboratory Significance
Safe, valid specimens support timely agent detection while preventing healthcare- and laboratory-associated transmission.
Differential Considerations
Separate diagnostic rejection (wrong specimen for method) from safety rejection (unsafe packaging), both may apply.
Comparison Tables
Transmission modes (introductory)
| Mode | Typical examples | Lab emphasis |
|---|---|---|
| Contact | C. difficile, MRSA (contact context) | Gloves, gowns, surface disinfection |
| Droplet | Selected respiratory pathogens | Face protection per risk assessment |
| Airborne | Selected agents (e.g., TB context) | Engineering controls / BSC as required locally |
| Vehicle | Contaminated coolers, food, water | Leak-proof transport; no shared wet contamination |
Classification Frameworks
Not applicable.
Laboratory Notes
- Treat every specimen as potentially infectious
- Verify method-specific stool/respiratory acceptance rules
- Follow institutional spill and courier SOPs
References
Authoritative textbooks, guidelines, and reviews supporting this reference entry. Verify reference intervals, critical limits, and reflex criteria against institutional protocols and current guideline editions.
Textbooks
- Forbes BA, Sahm DF, Weissfeld AS. Bailey & Scott's Diagnostic Microbiology. 15th ed. Elsevier; 2020.
- Mahon CR, Lehman DC, Manuselis G. Textbook of Diagnostic Microbiology. 6th ed. Elsevier; 2018.
- Carroll KC, Hobden JA, Miller S, et al. Jawetz, Melnick, & Adelberg's Medical Microbiology. 28th ed. McGraw-Hill; 2019.
- Murray PR, Rosenthal KS, Pfaller MA. Medical Microbiology. 9th ed. Elsevier; 2021.
CLSI and Professional Guidelines
- Clinical and Laboratory Standards Institute. Performance Standards for Antimicrobial Susceptibility Testing. CLSI document M100 (verify current edition and institutional adoption).
- Centers for Disease Control and Prevention / NIH. Biosafety in Microbiological and Biomedical Laboratories (BMBL). Current edition (verify institutional adoption).
Frequently Asked Questions
Common questions about using this Chain of Infection foundational topics Medical Laboratory Library reference in Medical Laboratory Science education.
What is the Chain of Infection laboratory reference?
Chain of Infection is a Foundational Topics entry in the LabPedia Medical Laboratory Library, written for Medical Laboratory Science reference lookup.
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