Automation in the Microbiology Laboratory: A Step-by-Step Guide to the Instruments

Walk into a modern clinical microbiology laboratory and the automation is not one machine but many, spread along the path a specimen takes from the moment it arrives to the moment a result is reported. Some labs have automated a single step; others have connected the whole line. To understand laboratory automation in microbiology, the clearest way is to follow a specimen through the lab and see which step each instrument takes over.

What "automation in microbiology" actually means

Automation in the microbiology laboratory is the use of instruments to take over the manual, repetitive, and time-consuming steps of culture-based testing, so that trained staff can spend their time on the steps that need judgment. It is not a single machine or a single decision. It is a spectrum: at one end, a lab automates just one step (for example, a standalone instrument that prepares media); at the other, every step is connected into one continuous, conveyor-linked system.

Microbiology automated later than other laboratory disciplines, and for a concrete reason. Clinical chemistry and hematology work mostly with liquid samples in tubes, which are straightforward for machines to move and measure. Microbiology works with living organisms growing on solid media, which must be plated, incubated over hours to days, and read by looking at colonies. Automating that is harder, which is why it arrived decades later and why it looks different from automation elsewhere in the laboratory.

The rest of this article follows a specimen through the laboratory, step by step, and shows which instrument automates each step and where to read about it in detail. At the end, it shows what happens when all these steps are connected into one system.

Following a specimen through an automated laboratory

Step 1: Preparing the culture media. Before any specimen is processed, the lab needs culture media, and making media by hand is one of the most laborious jobs in microbiology: weighing powder, dissolving it, sterilizing it, adding supplements, and pouring plates. Automated media preparation and dispensing systems take over the dissolving, sterilizing, supplement addition, and pouring, filling large numbers of plates at a consistent depth with minimal handling. See the full guide: automation in culture media preparation and dispensation.

Step 2: Planting and streaking the specimen. When a specimen arrives, it is inoculated onto the plate and streaked to spread it for isolated colonies. Done by hand with a loop, the pattern varies from one technologist to the next, which affects how well colonies separate. Automated specimen processors plant and streak the specimen in a uniform, reproducible pattern, improving colony isolation and freeing staff from a repetitive manual task. (This is the front end of the integrated systems described later; a dedicated guide to automated inoculation is planned.)

Step 3: Incubating the plates. Plated cultures are incubated at a controlled temperature and atmosphere so organisms can grow. The instrument that does this, the laboratory incubator, is one of the most fundamental pieces of laboratory equipment, and automated systems add smart, continuously monitored incubation. See: laboratory incubator.

Step 4: Reading the plates and counting colonies. After incubation, plates are examined for growth and colonies are counted, a step that is slow and variable when done by eye. Automated colony counters use a camera and image-analysis software to count colonies quickly and consistently, and to calculate results such as CFU/mL. The same digital-imaging approach lets modern systems read plates on a screen rather than by handling each one. See: colony counter.

Step 5: Identifying the organism. Once a colony is isolated, it must be identified. The manual route is a panel of biochemical tests read over hours; the automated routes are far faster. MALDI-TOF mass spectrometry identifies an organism from its protein fingerprint in minutes, and automated identification systems run miniaturized biochemical panels read by machine. See: MALDI-TOF mass spectrometry and automated identification and susceptibility testing.

Step 6: Testing antibiotic susceptibility. Finally, the organism is tested against antibiotics to guide treatment. Automated systems measure growth in the presence of each drug and derive a minimum inhibitory concentration, applying an expert system that flags implausible or resistance-suggesting results for review. See: automated identification and antimicrobial susceptibility testing.

A parallel workflow: blood cultures. Blood cultures follow their own automated path. An automated blood culture system continuously monitors sealed bottles and signals when an organism grows, replacing the manual checking of bottles. The flagged bottle then rejoins the main workflow at identification and susceptibility. See: BACTEC automated blood culture system.

From standalone instruments to full integration

The instruments above can be bought and used one at a time. A laboratory might automate only its media preparation, or add a MALDI-TOF for identification, and otherwise work manually. This is how most laboratories use automation: a few standalone instruments automating the busiest steps.

At the far end of the spectrum, all of these steps are physically connected. Total Laboratory Automation (TLA) links specimen processing, inoculation, incubation, and digital imaging along a conveyor, so a plate moves from step to step without being handled, and, crucially, is imaged without ever leaving the incubator. TLA is not a different kind of automation; it is the integrated version of the same workflow this guide has walked through, with the individual instruments connected into one line. For how the connected systems work, their benefits, and their limitations, see the full guide: Total Laboratory Automation in clinical microbiology.

The choice along this spectrum is mostly about scale and cost. Standalone instruments suit laboratories automating their busiest steps; full integration suits high-volume laboratories where the throughput justifies the large investment. The direction of travel, in microbiology as in the rest of the laboratory, is toward more automation over time.

Why automate microbiology at all: the shared benefits

Across every step, automation is adopted for the same handful of reasons:

Automation frees skilled staff for skilled work, taking over the repetitive low-skill steps (making media, streaking plates, counting colonies) so that trained microbiologists spend their time reading complex plates, identifying organisms, and interpreting results. It improves consistency, because a machine streaks, pours, and reads more uniformly than a tired human at the end of a shift. It increases throughput, letting a laboratory handle rising specimen numbers without proportionally more staff. And, in the integrated systems, it shortens turnaround time, which means the right treatment reaches the patient sooner.

The shared limitations

Automation is not right for every laboratory, and the trade-offs recur across the instruments:

The dominant one is cost. Automated instruments are capital investments, and the fully integrated systems are very expensive; they pay off only where specimen volume is high and steady. Automation also creates dependency: when a central instrument or an integrated line fails, testing can stall, so laboratories keep a manual fallback and service contracts, and must maintain staff competence in manual methods so skills do not fade. And not every specimen or every step suits automation; some specimen types and some specialized media still need manual handling.

How to remember

• Follow the specimen, not the machine. Automation in microbiology is a sequence of steps, each with its own instrument: media prep, planting, incubation, reading, identification, susceptibility. Understanding it means walking the workflow, not memorizing a list of machines.
• Standalone at one end, TLA at the other. Most labs automate a few steps with standalone instruments. Total Laboratory Automation is the same workflow with every step connected. TLA is the destination, not a different road.
• The reasons are always the same four. Free skilled staff, improve consistency, raise throughput, shorten turnaround. Every automated instrument is sold on some combination of these.
• The catch is always cost and dependency. Automation is a capital investment that pays off at volume, and it centralizes risk, so a manual backup is never optional.

Key facts

Where students get confused

"Automation in microbiology means Total Laboratory Automation." TLA is one point on a spectrum, the fully-integrated end. Most laboratories that use automation have a few standalone instruments (a media preparator, a MALDI-TOF, an automated susceptibility system), not a connected TLA line. Automation is the whole range; TLA is the most integrated form of it.

"Automation replaces the microbiologist." It replaces the repetitive manual steps, not the judgment. Reading complex plates, resolving flagged results, identifying difficult organisms, and interpreting results in the clinical context still need trained staff. Automation redirects expertise toward the work that needs it; it does not remove the expert.

"If a lab is automated, every step is automated." Rarely. Most automated laboratories automate their busiest steps and keep others manual. Weighing media powder, handling unusual specimens, and working up complex cultures are commonly still manual even in highly automated labs.

"More automation is always better." Only where the volume justifies it. Automated instruments are expensive capital investments that pay off at high, steady throughput. For a small, low-volume laboratory, manual methods can be more economical, and the dependency risk of centralized automation is a real cost.

References

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2. Bailey & Scott's Diagnostic Microbiology. Tille PM. 15th ed. St. Louis: Elsevier; 2022.
3. Leber AL, editor. Clinical Microbiology Procedures Handbook. 4th ed. Washington, DC: ASM Press; 2016. doi:10.1128/9781683670438.CMPH
4. Lippi G, Da Rin G. Advantages and limitations of total laboratory automation: a personal overview. Clin Chem Lab Med. 2019;57(6):802-811. doi:10.1515/cclm-2018-1323