Enterobacterales

Hafnia alvei

Gram-negative bacilli

Identification & Growth

Identification

Lysine and ornithine decarboxylase-positive, indole-negative, H2S-negative
Biochemical reactions are more pronounced at 25 °C than at 37 °C

Growth Conditions

MacConkey agar, lactose-negative, 35–37 °C, 24 h

Clinical Significance

Opportunistic infection: UTI, wound, bacteremia in hospitalized patients

Intrinsic Resistance

Inducible AmpC: ampicillin, amoxicillin-clavulanate and first-/second-generation cephalosporins should not be reported

Bench Alerts

Risk of AmpC derepression during third-generation cephalosporin therapy
The biochemical profile can be confused with Salmonella — confirm with serology

Clinical Notes

Clinical presentations

Rare opportunistic pathogen associated with urinary, respiratory and wound infections in debilitated patients.
Bacteremia and intra-abdominal infections have been described in immunocompromised patients or those with severe underlying disease.
Controversial role as an enteric pathogen in gastroenteritis, with reports linking it to diarrhea mainly in children.

Specimens and collection

Routine clinical specimens (urine, blood, secretions) are processed on standard media for Enterobacterales.
Stool culture may isolate the organism, but its clinical significance as a diarrheal agent should be interpreted cautiously.
Serial blood cultures confirm true bacteremia in patients with systemic signs of infection.

Epidemiology and at-risk populations

Part of the normal human and animal intestinal microbiota, considered a low-virulence opportunistic pathogen.
Invasive infections occur predominantly in neonates, the elderly and patients with significant comorbidities.
Healthcare-associated cases have been reported in neonatal and intensive care units.

Resistance and therapeutic implications

Produces an inducible chromosomal cephalosporinase (AmpC-like), conferring natural resistance to aminopenicillins.
Generally susceptible to extended-spectrum cephalosporins, carbapenems and fluoroquinolones, but individualized susceptibility testing is recommended.
Risk of inducible resistance should be considered when selecting prolonged beta-lactam therapy for severe infections.

Bench and reporting notes

Lactose-variable, oxidase-negative Gram-negative rod, identified by automated biochemical profiles or MALDI-TOF.
Positive ornithine decarboxylase and lack of motility at 36°C aid differentiation from other Enterobacterales.
Clinical significance in surveillance or stool specimens should be correlated with clinical presentation before reporting as a pathogen.

Sources

Educational decision-support content. It does not replace laboratory validation, current guidelines or review by the responsible professional.

FAQ: Frequently Asked Questions

How to identify Hafnia alvei in the lab?

Hafnia alvei is identified through lysine and ornithine decarboxylase-positive, indole-negative, h2s-negative, biochemical reactions are more pronounced at 25 °c than at 37 °c.

What are the intrinsic resistances of Hafnia alvei?

This organism is naturally resistant to inducible ampc: ampicillin, amoxicillin-clavulanate and first-/second-generation cephalosporins should not be reported. These drugs should not be reported as susceptible.

Where is Hafnia alvei commonly found?

It is typically associated with opportunistic infection: uti, wound, bacteremia in hospitalized patients.

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