CPT code 87077 – Aerobic bacterial identification billing guide

Key takeaways

CPT 87077 covers species-level identification of a single aerobic bacterium isolated from culture, not the initial culture itself or susceptibility testing.

It is separately billable from the primary culture code (87086 or 87070) and from susceptibility testing (87186), but each service needs its own supporting documentation.

Most denials occur because the lab report lacks a species-level result or the physician order does not specify organism identification as a separate service.

Claims management software like Pabau links the lab codes on a claim and flags missing documentation before submission.

CPT Code 87077: official descriptor and procedure overview

CPT Code 87077 carries the official AMA descriptor: Culture, bacterial; aerobic isolate, additional methods required for definitive identification, each isolate. It covers the laboratory work that follows a primary culture. Once colonies grow, a separate identification step names the organism to the species level.

The key phrase is “additional methods required.” Routine colony identification that happens as part of the primary culture is bundled into 87086 or 87070. CPT 87077 is appropriate only when the lab performs a distinct, documented identification procedure on an isolated organism.

How the identification step is performed and when to use it

The 87077 workflow begins after a primary culture grows visible colonies. 87086 covers quantitative urine cultures and 87070 covers other sources. The lab then selects an isolated colony and applies additional methods to identify the organism at the species level. Those methods include automated biochemical panels, MALDI-TOF mass spectrometry, and molecular probes. Which one a lab reaches for depends on the organism suspected and the equipment on hand.

Use 87077 when species-level identification is medically necessary and performed as a distinct laboratory service. Wound infections that need pathogen-directed antibiotic therapy are the common case. So are urinary tract infections where a positive growth result is not enough on its own. Respiratory specimens qualify too, when the clinician needs a named organism before prescribing.

• Do bill 87077 when the lab performs a separate, documented identification procedure on an isolated aerobic colony using biochemical, MALDI-TOF, or molecular methods.
• Do not bill 87077 when the organism is identified as part of the routine primary culture workflow and no additional identification step was performed.
• Do not bill 87077 for anaerobic organism identification (use 87076 instead).
• Do not bill 87077 for susceptibility or sensitivity testing (those are reported with 87186 or 87184/87185).

CPT 87077 vs adjacent codes: 87086, 87070, and 87186

Coders most often ask two questions. Can 87077 be stacked on 87086 or 87070 for the same specimen, and can 87186 be billed alongside it? 87077 and 87186 are generally separately billable. 87077 and the primary culture codes can also go on one claim, but only when both services were performed. The three stages below each carry their own codes and their own billing unit.

Can 87077 be billed with susceptibility testing?

Yes, in most cases. Organism identification (87077) and susceptibility testing (87186) are distinct laboratory services with different clinical purposes. Identification names the organism. Susceptibility testing then determines which antibiotics will work against it. They run in sequence, and each answers a different question.

No National Correct Coding Initiative (NCCI) bundling edit universally prohibits billing 87077 and 87186 together. That said, payer-specific policies vary. Some Medicare Administrative Contractors and commercial payers require a linked physician order specifying both services before reimbursing both on the same claim. Check your MAC’s LCD and your payer contracts before you assume the two always separate.

Documentation requirements for an 87077 claim

Documentation is what separates a paid 87077 claim from a denied one. Labs that submit without the four elements below see the code returned again and again.

• Physician order: The ordering provider’s documentation must specify that organism identification to species level is required, not just a culture. A generic “culture and sensitivity” order typically covers 87086/87070 and 87186. It may not clearly authorize the separate 87077 step, so amend the order language where possible.
• Lab report with a species-level result: The final laboratory report must name the identified organism to species level. Staphylococcus aureus qualifies, and “gram-positive cocci” does not. A report that says only “organism identified” will not support the claim.
• Primary culture documentation: The 87077 claim must be linkable to a primary culture event. That means either a co-billed 87086/87070 claim, or an internal lab record showing a colony was isolated before identification began.
• Medical necessity (ICD-10 linkage): A supporting diagnosis must connect the identification to a clinical need. Without a plausible ICD-10 code tying the specimen to an active or suspected infection, the claim fails medical necessity review.

Capture the primary culture and the identification step on the same internal record. That keeps the claim, the lab report, and the order in agreement when a payer asks for support.

ICD-10 codes that support medical necessity

The ICD-10-CM codes below appear most frequently on claims billed alongside 87077. Payers expect the listed diagnosis to be consistent with the specimen source and the clinical context documented in the ordering note.

For Medicare claims, the Local Coverage Determination (LCD) for your MAC jurisdiction specifies which diagnoses qualify as covered indications. LCDs for microbiology codes vary by region, so confirm coverage criteria with your MAC before you assume Medicare covers the code everywhere.

Medicare and payer reimbursement under the 2026 fee schedule

CPT 87077 is priced under the Clinical Laboratory Fee Schedule (CLFS), not the Physician Fee Schedule. The CLFS sets national Medicare payment rates for laboratory services with no geographic adjustment. The allowed amount is therefore consistent across MAC jurisdictions, unlike PFS codes priced with Geographic Practice Cost Indices.

For the current allowed amount, check the CMS Clinical Laboratory Fee Schedule file. CLFS rates for microbiology codes typically run in the low-to-mid single digits per isolate. CMS updates the file annually, so confirm 2026 amounts against the current release before you quote a figure.

Labs submit 87077 claims electronically in the 837P format. Pabau’s Claim.MD integration reaches thousands of US payers and returns Electronic Remittance Advice (835) files, so payments can be reconciled against expected CLFS amounts. Where the lab code or the linked diagnosis is mapped wrongly on the way out, the remittance is where it surfaces.

Private payer variability: Commercial payer rates for 87077 differ from Medicare CLFS amounts. Some payers price microbiology identification codes at a percentage of Medicare, commonly 100-130%. Others use internally negotiated fee schedules, so pull your own contracts before quoting an expected reimbursement to billing teams.

Common denial reasons and how to resolve them

Most 87077 rejections trace back to five patterns, and each one has a specific fix. Read the CARC on the remittance first, because it tells you which pattern applies. Our wider guide to denial codes covers the ones that fall outside this table.

Build a workflow step for 87077 claims that arrive without a linked 87086 or 87070 on the same date of service. Those are the ones a payer bundles first.

Billing multiple organisms: units and per-isolate rules

The AMA descriptor specifies “each isolate,” so 87077 can be billed once per aerobic organism that required additional identification methods. Two aerobic organisms from one specimen, each needing a distinct identification procedure, can in theory support two units.

In practice, per-isolate billing is where payer policies diverge most sharply from the AMA descriptor. Several Medicare Administrative Contractors and commercial payers apply a one-unit-per-date-of-service policy for 87077, whatever the organism count. Others follow the descriptor and reimburse per isolate, provided the lab report documents each organism separately.

• Before billing multiple units: Check your MAC’s LCD and your commercial payer contracts for explicit per-isolate language. Do not assume the “each isolate” descriptor authorizes multiple units without that confirmation.
• How to submit multiple units: Use a separate claim line per isolate rather than one line with a quantity above one. Each line carries the same specimen date of service and the same primary culture claim. The lab report attachment names the organism behind each line.
• Documentation per isolate: Each claimed isolate needs its own species-level entry in the lab report. A report listing two organisms with only one named to species level will not support two billed units.
• Payer preauthorization: Some payers require notification when more than one unit of a microbiology identification code is billed on one date of service. Confirm the notification requirement before you submit.

A clean first submission needs the lab report, the ordering note, and payer policy confirmation on file before the claim goes out. Retroactive appeals on per-isolate denials are winnable, but they cost weeks of staff time.

How Pabau keeps 87077 claims linked and documented

Most labs hold the primary culture result, the identification result, and the physician order in three separate places. The claim gets built from one of them, and the payer asks for the other two.

Pabau, practice management software built for clinical practices, keeps the order, the lab result, and the claim on one patient record. When a coder adds 87077, the linked 87086 or 87070 and the supporting ICD-10 code are already on screen.

Claims then go out through Claim.MD, and the 835 files come back into the same record for reconciliation. Teams that want cleaner claims management get that linkage checked before submission rather than after a denial.

Reduce lab billing denials before they happen

Pabau’s claims management software checks code linkages, flags missing lab documentation, and reaches thousands of US payers through our Claim.MD integration.

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Conclusion

87077 has a narrow scope, and its billing rules follow from that scope. It pays for one aerobic isolate, identified to species level by a method the lab performed and documented.

The denials come from treating that identification as part of the primary culture. Order it separately, name the species in the report, and link a diagnosis that fits the specimen. Those three habits settle most of what a payer would otherwise send back.

Labs seeing repeat 87077 rejections usually have the evidence on file and no way to attach it to the claim. Book a demo to see how Pabau connects the order, the lab report, and the claim in one record.

Continue your research

Need to understand how clearinghouse claim submission works end to end? Medical claims clearinghouse guide explains how 837 files move from your billing system to payers and back.

Dealing with repeated denial codes on lab claims? Electronic remittance advice (ERA) shows how to read 835 files and match CARC codes to specific line-item denials.

Want to verify payer credentialing before submitting microbiology claims? Insurance credentialing guide covers the enrollment steps that affect claim acceptance by MAC and commercial payers.

Need the claim right on the first pass? Clean claim guide lists the fields a payer checks before it accepts a claim for adjudication.

Working a backlog of rejected lab claims? Denial management in healthcare sets out a workflow for sorting, appealing, and preventing repeat denials.

Frequently asked questions