B96.21 Shiga toxin-producing Escherichia coli [E. coli] [STEC] O157 as the cause of diseases classified elsewhere

Billable ICD-10-CM code, FY2026.

Applicable to

• E. coli O157:H- (nonmotile) with confirmation of Shiga toxin
• E. coli O157 with confirmation of Shiga toxin when H antigen is unknown, or is not H7
• O157:H7 Escherichia coli [E. coli] with or without confirmation of Shiga toxin-production
• Shiga toxin-producing Escherichia coli [E. coli] O157:H7 with or without confirmation of Shiga toxin-production
• STEC O157:H7 with or without confirmation of Shiga toxin-production

MS-DRG index

Defines the logic of DRG(s) 867-869 in MDC 18.

Approximate ICD-9-CM (GEMs)

• 041.41 Shiga toxin-producing Escherichia coli [E. coli] (STEC) O157

Medicare Code Edits (MCE v43.1 (April 2026))

• Unacceptable principal diagnosis: These codes describe a circumstance which influences care but is not a current illness or injury, or capture only an underlying condition, and are unacceptable as principal diagnosis.

Code annotations containing back-references to B96.21

Back-references to B96.2

• Use Additional: D59.31 Infection-associated hemolytic-uremic syndrome ("E. coli infection (B96.2-)")

Back-references to B96

• Use Additional: A48.3 Toxic shock syndrome ("code to identify the organism (B95, B96)")
• Type 1 Excludes: A49 Bacterial infection of unspecified site ("bacterial agents as the cause of diseases classified elsewhere (B95-B96)")
• Use Additional: E06.0 Acute thyroiditis ("code (B95-B97) to identify infectious agent.")
• Use Additional: G00.8 Other bacterial meningitis ("code to further identify organism (B96.-)")
• Use Additional: G06 Intracranial and intraspinal abscess and granuloma ("code (B95-B97) to identify infectious agent.")
• Use Additional: H65 Nonsuppurative otitis media ("infectious agent (B95-B97)")
• Use Additional: I30.1 Infective pericarditis ("code (B95-B97) to identify infectious agent")
• Use Additional: I33.0 Acute and subacute infective endocarditis ("code (B95-B97) to identify infectious agent")
• Use Additional: I40.0 Infective myocarditis ("code (B95-B97) to identify infectious agent")
• Use Additional: J01 Acute sinusitis ("code (B95-B97) to identify infectious agent.")
• Use Additional: J02.8 Acute pharyngitis due to other specified organisms ("code (B95-B97) to identify infectious agent")
• Use Additional: J03.8 Acute tonsillitis due to other specified organisms ("code (B95-B97) to identify infectious agent.")
• Use Additional: J04 Acute laryngitis and tracheitis ("code (B95-B97) to identify infectious agent.")
• Use Additional: J05 Acute obstructive laryngitis [croup] and epiglottitis ("code (B95-B97) to identify infectious agent.")
• Use Additional: J06.9 Acute upper respiratory infection, unspecified ("code (B95-B97) to identify infectious agent, if known, such as:")
• Use Additional: J32 Chronic sinusitis ("infectious agent (B95-B97)")
• Use Additional: J36 Peritonsillar abscess ("code (B95-B97) to identify infectious agent.")
• Use Additional: J37 Chronic laryngitis and laryngotracheitis ("infectious agent (B95-B97)")
• Use Additional: J85 Abscess of lung and mediastinum ("code (B95-B97) to identify infectious agent.")
• Use Additional: J86 Pyothorax ("code (B95-B97) to identify infectious agent.")
• Use Additional: J95.851 Ventilator associated pneumonia ("code to identify the organism, if known (B95.-, B96.-, B97.-)")
• Use Additional: K65 Peritonitis ("code (B95-B97), to identify infectious agent, if known")
• Use Additional: K95.01 Infection due to gastric band procedure ("bacterial and viral infectious agents (B95.-, B96.-)")
• Use Additional: K95.81 Infection due to other bariatric procedure ("bacterial and viral infectious agents (B95.-, B96.-)")
• Use Additional: L02 Cutaneous abscess, furuncle and carbuncle ("code to identify organism (B95-B96)")
• Use Additional: M00.8 Arthritis and polyarthritis due to other bacteria ("code (B96) to identify bacteria")
• Use Additional: M46.3 Infection of intervertebral disc (pyogenic) ("code (B95-B97) to identify infectious agent.")
• Use Additional: M60.0 Infective myositis ("code (B95-B97) to identify infectious agent")
• Use Additional: M65.0 Abscess of tendon sheath ("code (B95-B96) to identify bacterial agent.")
• Use Additional: M71.0 Abscess of bursa ("code (B95.-, B96.-) to identify causative organism")
• Use Additional: M71.1 Other infective bursitis ("code (B95.-, B96.-) to identify causative organism")
• Use Additional: M72.6 Necrotizing fasciitis ("code (B95.-, B96.-) to identify causative organism")
• Use Additional: M72.8 Other fibroblastic disorders ("code to (B95.-, B96.-) identify causative organism")
• Use Additional: M86 Osteomyelitis ("code (B95-B97) to identify infectious agent")
• Use Additional: N10 Acute pyelonephritis ("code (B95-B97), to identify infectious agent.")
• Use Additional: N11 Chronic tubulo-interstitial nephritis ("code (B95-B97), to identify infectious agent.")
• Use Additional: N13.6 Pyonephrosis ("code (B95-B97), to identify infectious agent.")
• Use Additional: N30 Cystitis ("code to identify infectious agent (B95-B97)")
• Use Additional: N34 Urethritis and urethral syndrome ("code (B95-B97), to identify infectious agent.")
• Use Additional: N39.0 Urinary tract infection, site not specified ("code (B95-B97), to identify infectious agent.")
• Use Additional: N41 Inflammatory diseases of prostate ("code (B95-B97), to identify infectious agent.")
• Use Additional: N43.1 Infected hydrocele ("code (B95-B97), to identify infectious agent")
• Use Additional: N45 Orchitis and epididymitis ("code (B95-B97), to identify infectious agent.")
• Use Additional: N47.6 Balanoposthitis ("code (B95-B97), to identify infectious agent.")
• Use Additional: N47.7 Other inflammatory diseases of prepuce ("code (B95-B97), to identify infectious agent.")
• Use Additional: N48.1 Balanitis ("code (B95-B97), to identify infectious agent")
• Use Additional: N48.2 Other inflammatory disorders of penis ("code (B95-B97), to identify infectious agent.")
• Use Additional: N49 Inflammatory disorders of male genital organs, not elsewhere classified ("code (B95-B97), to identify infectious agent")
• Use Additional: N70 Salpingitis and oophoritis ("code (B95-B97), to identify infectious agent")
• Use Additional: N71 Inflammatory disease of uterus, except cervix ("code (B95-B97), to identify infectious agent")
• Use Additional: N72 Inflammatory disease of cervix uteri ("code (B95-B97), to identify infectious agent")
• Use Additional: N73 Other female pelvic inflammatory diseases ("code (B95-B97), to identify infectious agent.")
• Use Additional: N76 Other inflammation of vagina and vulva ("code (B95-B97), to identify infectious agent")
• Use Additional: O03.37 Sepsis following incomplete spontaneous abortion ("code to identify infectious agent (B95-B97)")
• Use Additional: O03.87 Sepsis following complete or unspecified spontaneous abortion ("code to identify infectious agent (B95-B97)")
• Use Additional: O04.87 Sepsis following (induced) termination of pregnancy ("code to identify infectious agent (B95-B97)")
• Use Additional: O07.37 Sepsis following failed attempted termination of pregnancy ("code (B95-B97), to identify infectious agent")
• Use Additional: O08.82 Sepsis following ectopic and molar pregnancy ("code (B95-B97), to identify infectious agent")
• Use Additional: O23 Infections of genitourinary tract in pregnancy ("code to identify organism (B95.-, B96.-)")
• Use Additional: O75.3 Other infection during labor ("code (B95-B97), to identify infectious agent")
• Use Additional: O85 Puerperal sepsis ("code (B95-B97), to identify infectious agent")
• Use Additional: O86 Other puerperal infections ("code (B95-B97), to identify infectious agent")
• Use Additional: P23.6 Congenital pneumonia due to other bacterial agents ("code (B95-B96) to identify organism")
• Use Additional: P36.8 Other bacterial sepsis of newborn ("code from category B96 to identify organism")

Diagnosis Index entries for B96.21

• Escherichia coli (E. coli), as cause of disease classified elsewhere › O157
• Escherichia coli (E. coli), as cause of disease classified elsewhere › O157 with confirmation of Shiga toxin when H antigen is unknown, or is not H7
• Escherichia coli (E. coli), as cause of disease classified elsewhere › O157:H- (nonmotile) with confirmation of Shiga toxin
• Escherichia coli (E. coli), as cause of disease classified elsewhere › O157:H7 with or without confirmation of Shiga toxin-production

Nearby codes

• B96 Other bacterial agents as the cause of diseases classified elsewhere
• B96.0 Mycoplasma pneumoniae [M. pneumoniae] as the cause of diseases classified elsewhere
• B96.1 Klebsiella pneumoniae [K. pneumoniae] as the cause of diseases classified elsewhere
• B96.2 Escherichia coli [E. coli ] as the cause of diseases classified elsewhere
• B96.20 Unspecified Escherichia coli [E. coli] as the cause of diseases classified elsewhere
• B96.21 Shiga toxin-producing Escherichia coli [E. coli] [STEC] O157 as the cause of diseases classified elsewhere (this code)
• B96.22 Other specified Shiga toxin-producing Escherichia coli [E. coli] [STEC] as the cause of diseases classified elsewhere
• B96.23 Unspecified Shiga toxin-producing Escherichia coli [E. coli] [STEC] as the cause of diseases classified elsewhere
• B96.29 Other Escherichia coli [E. coli] as the cause of diseases classified elsewhere
• B96.3 Hemophilus influenzae [H. influenzae] as the cause of diseases classified elsewhere
• B96.4 Proteus (mirabilis) (morganii) as the cause of diseases classified elsewhere