ICD-10 code B95.6 identifies Staphylococcus aureus as the causative organism behind a disease or infection coded elsewhere in the classification. It sits within Section B95–B97 (Bacterial and Viral Infectious Agents) and functions exclusively as a secondary, supplemental code — never as a standalone or principal diagnosis. Critically for coders: B95.6 itself is a non-billable header code. For FY 2026 HIPAA-covered claim submission, you must report either B95.61 (Methicillin susceptible Staphylococcus aureus / MSSA) or B95.62 (Methicillin resistant Staphylococcus aureus / MRSA) to capture the required level of specificity.
What Does ICD-10 Code B95.6 Mean?
B95.6 is a category-level code that classifies Staphylococcus aureus — commonly called “Staph aureus” — as the etiologic agent responsible for a disease that is coded in a different chapter of ICD-10-CM. The code does not describe the disease itself; it identifies who the culprit organism is when a “use additional code” instruction appears on the primary disease code.
Key attributes at a glance:
- Code status: Non-billable header — requires 5th character to be valid for submission
- Valid billable child codes: B95.61 (MSSA) and B95.62 (MRSA)
- Code type: Supplemental/additional code only — never principal diagnosis
- Applicable setting: Inpatient and outpatient, when the primary disease code instructs “use additional code to identify organism”
- Effective FY 2026: Valid from October 1, 2025 through September 30, 2026 (no description change)
What Does B95.6 Cover — and What Are Its Subcategories?
The B95.6 category captures Staph aureus as the documented cause of infections that are classified in other chapters — for example, pneumonia coded under J15.21 or osteomyelitis coded under M86. The organism identification comes from the B95.6x code; the infection site and type come from the primary code.
Clinical conditions commonly requiring a B95.6x supplemental code include:
- Staph aureus pneumonia (primary code J15.211 / J15.212, supplemented by B95.61 or B95.62)
- Staph aureus osteomyelitis (primary code from M86 category)
- Staph aureus bacteremia or septicemia — note that A41.01 (MSSA sepsis) and A41.02 (MRSA sepsis) are combination codes that do not require a separate B95.6x code
- Post-procedural wound infections with documented Staph aureus etiology
- Skin and soft tissue infections coded from L00–L08 with Staph aureus documented as causative
What Does This Code Specifically Exclude?
Per the ICD-10-CM Official Coding Guidelines, Section B95–B97 notes contain the following exclusions and restrictions:
- Excludes 1 (never code together): Certain localized infections — see the body-system chapter instead; do not add B95.6x if the combination code already captures the organism
- Excludes 2 (may co-exist separately): Carrier or suspected carrier of infectious disease (Z22.-); infectious and parasitic diseases complicating pregnancy, childbirth, and the puerperium (O98.-); infectious diseases specific to the perinatal period (P35–P39)
- B95.6x codes are never appropriate when a combination code in the tabular list already identifies both the condition and the Staph aureus organism
When Is B95.6 the Right Code — and When Is It Not Billable?
Understanding when to reach for B95.61 vs. B95.62 vs. neither is where the majority of coding errors occur. Follow this decision sequence:
- Confirm the primary disease code has a “use additional code” note directing you to identify the organism — if that instruction is absent, do not add a B95.6x code
- Check for a combination code that already captures Staph aureus and the site/condition (e.g., A41.01, A41.02, J15.211, J15.212) — if one exists, the B95.6x code is redundant and should not be added
- Review the culture and sensitivity (C&S) report or microbiology documentation to confirm the organism is definitively identified as Staphylococcus aureus
- Determine methicillin susceptibility: If MSSA → B95.61; if MRSA → B95.62; if susceptibility is not documented → query the provider before defaulting to B95.62
- Confirm the code is secondary: Place B95.61 or B95.62 after the primary disease code in all settings — it cannot lead the claim
How Does B95.61 Differ From B95.62?
The distinction between MSSA and MRSA is not merely clinical — it has direct implications for medical necessity documentation, antibiotic selection justification, and infection control reporting.
| Code | Full Description | Organism Type | Key Clinical Distinction |
|---|---|---|---|
| B95.61 | MSSA infection as cause of diseases classified elsewhere | Methicillin-susceptible Staph aureus | Treatable with beta-lactam antibiotics (oxacillin, nafcillin, cefazolin) |
| B95.62 | MRSA infection as cause of diseases classified elsewhere | Methicillin-resistant Staph aureus | Requires vancomycin, daptomycin, or linezolid; isolation precautions often required |
| B95.6 | Parent/header code only | N/A — non-billable | Never submit on a claim; use B95.61 or B95.62 |
| B95.8 | Unspecified Staphylococcus | Species not identified | Use only when genus Staph is documented but species cannot be determined |
What Documentation Is Required to Support B95.61 or B95.62?
Because B95.6x codes identify a specific causative organism, the clinical documentation must directly support the organism identification. In practice, auditors flag B95.6x codes most often when the supporting laboratory findings are absent from the record or when the provider’s note references the organism only in passing without connecting it to the active diagnosis.
What Must the Provider Document in the Clinical Notes?
- An explicit statement identifying Staphylococcus aureus as the causative organism of the active infection being coded
- The methicillin susceptibility status — MSSA or MRSA — to support the correct 5th-character selection
- The clinical relationship between the organism and the coded disease (e.g., “Staph aureus confirmed as causative agent of left femur osteomyelitis”)
- Documentation of treatment decisions consistent with the identified organism (e.g., MRSA-targeted therapy for B95.62)
Which Diagnostic or Lab Results Support This Code?
- Culture and sensitivity (C&S) report identifying Staphylococcus aureus with antibiotic susceptibility panel — the gold standard supporting document
- Blood culture results in bacteremia cases
- Wound culture or tissue biopsy culture results for soft tissue or bone infections
- Antibiotic resistance testing confirming methicillin susceptibility or resistance (oxacillin MIC or PCR-based MRSA screening)
- Physician attestation in cases where culture results are pending but clinical presentation is consistent and treatment is initiated
What Is the Documentation Standard for Inpatient vs. Outpatient Settings?
| Setting | Documentation Standard |
|---|---|
| Inpatient | Physician must document the Staph aureus etiology and MSSA/MRSA status in the H&P, progress notes, or discharge summary — coder may code from any authenticated provider entry |
| Outpatient | Coder codes only confirmed diagnoses; if culture results are pending at time of the visit, query the provider or hold the claim until confirmation is received |
| Both settings | Lab reports alone are not sufficient — the treating provider must acknowledge and document the finding in their clinical note |
How Does B95.6 Affect Medical Billing and Claims?
B95.61 and B95.62 function as secondary diagnosis codes and influence claim processing primarily by supporting medical necessity for the primary coded condition, justifying antibiotic selection and intensity of service. They can also affect DRG assignment in the inpatient setting when they contribute to MCC (Major Complicating Condition) status — MRSA in particular is recognized as an MCC in many MS-DRG groupings.
Key billing considerations:
- B95.6x codes are unacceptable as principal diagnoses — submitting them in the first diagnosis position will result in claim rejection by the Medicare Code Editor (MCE) and most commercial payers
- MRSA (B95.62) may trigger infection control reporting requirements in certain states under public health surveillance rules
- DRG impact: When B95.62 appears as a secondary code alongside a qualifying principal diagnosis, it may elevate the DRG to a higher-weighted MCC tier, increasing reimbursement
- Do not include the decimal point when filing electronically — submit as B9561 or B9562, not B95.61 or B95.62
What CPT or Procedure Codes Are Commonly Billed With B95.6x?
| CPT Code | Description | Common Pairing Context |
|---|---|---|
| 87040 | Culture, bacterial; blood | Bacteremia workup confirming Staph aureus |
| 87070 | Culture, bacterial; other source | Wound or tissue culture |
| 87077 | Bacterial identification by additional methods | Susceptibility confirmation |
| 87186 | Susceptibility studies, antimicrobial agent | MIC testing for MSSA/MRSA determination |
| 99232–99233 | Subsequent hospital care | Inpatient management of Staph aureus infections |
Are There Any Prior Authorization or Coverage Restrictions?
- Most payers do not require prior authorization specifically for the B95.6x codes themselves, as they are supplemental codes
- Vancomycin infusion or prolonged IV antibiotic therapy for MRSA cases may require prior authorization under certain commercial plans
- LCD (Local Coverage Determination) for infectious disease services may specify organism documentation requirements — verify the applicable MAC’s LCDs when billing high-complexity infection management
What Coding Errors Should You Avoid With B95.6?
The most audit-prone errors involving B95.6x codes cluster around two themes: using the non-billable parent code B95.6 on a claim, and placing these supplemental codes in the wrong sequence.
- Submitting B95.6 (non-billable parent) instead of B95.61 or B95.62 — this is the single most common error; always code to the full level of specificity
- Listing B95.61 or B95.62 as the principal diagnosis — these codes cannot lead any claim in any setting; doing so will trigger MCE edits
- Adding B95.6x when a combination code already captures both the condition and the organism — redundant code pairs (e.g., A41.01 + B95.61) are a coding error
- Defaulting to B95.62 (MRSA) when susceptibility is undocumented — this overstates clinical severity and creates audit exposure; query the provider or use B95.8 if species only is confirmed
- Omitting B95.6x entirely when the primary code has a “use additional code” instruction — this under-codes the claim and fails to support medical necessity for organism-specific treatment
What Do Auditors Look for When Reviewing Claims With B95.6x?
- Laboratory culture and sensitivity documentation matching the organism coded
- Provider attestation connecting the identified organism to the active diagnosis in the clinical note — not just in a lab report alone
- Appropriate antibiotic selection consistent with MSSA vs. MRSA designation
- Absence of a combination code that would make the B95.6x redundant
- Correct sequencing — B95.6x in secondary or additional code position only
How Does B95.6 Relate to Other ICD-10 Codes?
Understanding B95.6’s relationship to adjacent codes prevents both under-coding and redundant pairing errors.
| Code | Description | Relationship to B95.6 | Key Distinction |
|---|---|---|---|
| B95.61 | MSSA as cause of diseases classified elsewhere | Child code of B95.6 — billable | Use when susceptibility is documented as methicillin-susceptible |
| B95.62 | MRSA as cause of diseases classified elsewhere | Child code of B95.6 — billable | Use when resistance is confirmed |
| B95.8 | Unspecified Staphylococcus | Sibling code in B95 category | Use when genus is confirmed but species (aureus) is not documented |
| B95.7 | Other Staphylococcus | Sibling code | Use for coagulase-negative Staph or other non-aureus species |
| A41.01 | Sepsis due to MSSA | Combination code — separate chapter | Includes organism; do NOT add B95.61 |
| A41.02 | Sepsis due to MRSA | Combination code — separate chapter | Includes organism; do NOT add B95.62 |
| Z16.- | Resistance to antimicrobial drugs | Companion code | May be added alongside B95.62 to further specify resistance pattern |
What Is the Correct Code Sequencing When B95.6x Appears With Other Diagnoses?
Per the ICD-10-CM Official Coding Guidelines, Section I.C.1, infectious agent codes in the B95–B97 range follow a strict secondary sequencing rule:
- Sequence the primary disease code first (e.g., the osteomyelitis, pneumonia, or wound infection code)
- Add B95.61 or B95.62 as a secondary/additional code to identify the causative organism
- If antimicrobial resistance is also documented, add a code from Z16.- after B95.62 to specify the resistance type
- Do not sequence B95.6x ahead of any other code under any circumstance
Real-World Coding Scenario — How B95.6 Is Applied in Practice
A 67-year-old Medicare patient is admitted with a right knee periprosthetic joint infection following total knee arthroplasty performed three months earlier. The wound culture returns positive for Staphylococcus aureus with a reported oxacillin MIC of 0.25 µg/mL — confirming methicillin susceptibility. The orthopedic surgeon documents in the progress note: “Staph aureus (MSSA) confirmed as causative agent of right knee periprosthetic infection. Initiating cefazolin IV per ID recommendation.”
Correct Code Application
- T84.51XA — Infection and inflammatory reaction due to internal right hip prosthesis (or equivalent knee prosthesis code — T84.53XA), initial encounter
- B95.61 — MSSA infection as the cause of diseases classified elsewhere
- Rationale: The primary code captures the infected prosthetic device; B95.61 is added per the “use additional code to identify the infectious agent” instruction on the prosthetic infection codes
Common Mistake in This Scenario
- Incorrect code selected: B95.62 (MRSA) instead of B95.61 (MSSA)
- Why it fails: The culture confirms MSSA (oxacillin-susceptible). Using B95.62 misrepresents the organism’s antimicrobial resistance profile, overstates clinical complexity, and could trigger an audit flag when cefazolin — a beta-lactam appropriate for MSSA but not for MRSA — appears on the medication record
- Second common error: Submitting the parent code B95.6 instead of drilling down to B95.61 — this renders the claim non-compliant and may trigger rejection
Frequently Asked Questions About ICD-10 Code B95.6
Is ICD-10 Code B95.6 Billable for FY 2026?
ICD-10 code B95.6 is not billable for FY 2026 or any prior fiscal year — it is a non-specific header code that requires further character specificity. Coders must select either B95.61 (MSSA) or B95.62 (MRSA) for any HIPAA-covered claim submission. Submitting B95.6 as written will result in claim rejection.
What Is the Difference Between B95.61 and B95.62?
B95.61 identifies methicillin-susceptible Staphylococcus aureus (MSSA) as the causative organism, while B95.62 identifies methicillin-resistant Staphylococcus aureus (MRSA). The distinction requires documented culture and susceptibility testing; coders should not default to B95.62 based on clinical suspicion alone without provider attestation or confirmed laboratory results.
Can B95.62 Be Used as a Principal Diagnosis?
B95.62 — and all codes in the B95–B97 section — can never be used as a principal or primary diagnosis. These codes are designated as supplemental organism-identification codes only, as stated in the instructional note at the top of Section B95–B97 in the ICD-10-CM Official Coding Guidelines. Payers will reject any claim where a B95.6x code appears as the first-listed diagnosis.
When Should I Add B95.6x vs. Using a Combination Code?
You should not add B95.6x when the tabular list provides a combination code that already incorporates both the condition and the Staphylococcus aureus organism. For example, J15.211 (pneumonia due to MSSA) and A41.01 (sepsis due to MSSA) are combination codes — adding B95.61 alongside them is redundant and a coding error. Only add B95.61 or B95.62 when a “use additional code” instruction explicitly appears on the primary code.
What Documentation Do I Need to Code B95.62 for MRSA?
To accurately report B95.62, the medical record must include a laboratory report confirming Staphylococcus aureus with methicillin resistance (typically via oxacillin MIC ≥4 µg/mL or positive mecA gene PCR), combined with a treating provider’s note that explicitly acknowledges the MRSA finding in connection with the active diagnosis. A lab report alone — without provider documentation — is insufficient per outpatient coding guidelines.
Does B95.62 Affect DRG Assignment?
Yes — in the inpatient setting, MRSA (B95.62) can function as a Major Complicating Condition (MCC) when it accompanies qualifying principal diagnoses, potentially shifting the case to a higher-weighted DRG tier and increasing reimbursement. Coders should ensure that when MRSA is documented and clinically relevant, B95.62 is captured as a secondary diagnosis so DRG grouping software correctly assigns MCC status.
Should I Add Z16.- When Coding B95.62?
The Z16 code category (Resistance to antimicrobial drugs) may be added alongside B95.62 when documentation further specifies the resistance pattern — for example, resistance to vancomycin or daptomycin. It is not required for every MRSA case but provides additional clinical specificity that can support medical necessity for high-cost antimicrobial therapy.
Key Takeaways
- B95.6 is non-billable — always use B95.61 (MSSA) or B95.62 (MRSA) for any HIPAA-covered claim submission
- These codes are supplemental/additional codes only — they can never serve as a principal or first-listed diagnosis
- Code selection between B95.61 and B95.62 depends on documented methicillin susceptibility from culture and sensitivity results — do not default to MRSA without confirmation
- Combination codes such as A41.01 (MSSA sepsis) and J15.211 (MSSA pneumonia) already incorporate the organism — do not add B95.6x redundantly
- B95.62 (MRSA) may elevate DRG weight as an MCC in inpatient settings — accurate capture improves reimbursement accuracy
- Auditors specifically look for lab documentation matching the organism coded and provider attestation connecting the organism to the active diagnosis
- Consult the ICD-10-CM Official Coding Guidelines, Section I.C.1 and the tabular instructional notes at B95–B97 for sequencing rules governing these supplemental organism codes