Elizabethkingia meningoseptica
Slender, non-fermenting Gram-negative bacilli
Identification & Growth
Identification
- Oxidase-positive, indole-positive (weak; use Kovacs reagent on pure culture), some isolates fail to grow on MacConkey agar
- Colonies with a pale-yellow pigment
Growth Conditions
- Blood agar 35 °C, 24–48 h; grows best at 30 °C
Clinical Significance
- Neonatal meningitis, ICU bacteremia, ventilator-associated pneumonia
Intrinsic Resistance
- Chromosomal metallo-beta-lactamase and extended-spectrum beta-lactamase: carbapenems, cephalosporins, aztreonam and colistin have no activity
Bench Alerts
- Carbapenem resistance is intrinsic, not acquired — do not report as an epidemiological finding
- Vancomycin, rifampicin, minocycline and fluoroquinolones are the usual alternatives
Clinical Notes
Clinical presentations
- Neonatal meningitis and late-onset sepsis in preterm infants, with high lethality and neurological sequelae.
- In adults, catheter-associated bacteremia and pneumonia during prolonged intensive care.
- Ocular and wound infections after exposure to contaminated solutions or water.
Specimens and collection
- CSF and blood culture are the priority specimens in suspected neonatal disease; collect before antimicrobials whenever possible.
- Tracheal aspirate or bronchoalveolar lavage in respiratory disease under mechanical ventilation.
- Collect environmental samples (taps, humidifiers, solutions) when cases cluster in the neonatal ICU.
Epidemiology and at-risk populations
- Environmental organism of fresh water and hospital water systems; it survives in aqueous solutions and moist surfaces.
- Outbreaks are described in neonatal and adult ICUs, often linked to a water source or shared equipment.
- Highest-risk populations: preterm infants, immunosuppressed patients and those with prolonged admission and broad-spectrum therapy.
Resistance and therapeutic implications
- It produces metallo-beta-lactamase and class A beta-lactamase: usual resistance to carbapenems, broad-spectrum cephalosporins and aztreonam.
- Intrinsic resistance to colistin and aminoglycosides, which rules out the usual empirical Gram-negative regimen.
- Trimethoprim-sulfamethoxazole, minocycline, fluoroquinolones and rifampicin are more often active; confirm by MIC and discuss with infectious diseases.
Bench and reporting notes
- Non-fermenting Gram-negative rod, oxidase-positive, indole-positive (weak reaction, read with Kovács) and producing a pale-yellow pigment.
- Some strains fail to grow on MacConkey agar, which delays diagnostic suspicion.
- Notify the clinician and infection control immediately: the resistance profile inverts standard empirical therapy.
Sources
- EUCAST — Expert rules and expected resistant phenotypes
- UKHSA — Standards for Microbiology Investigations (SMI)
- IDSA — Practice guidelines
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 Elizabethkingia meningoseptica in the lab?
Elizabethkingia meningoseptica is identified through oxidase-positive, indole-positive (weak; use kovacs reagent on pure culture), some isolates fail to grow on macconkey agar, colonies with a pale-yellow pigment.
What are the intrinsic resistances of Elizabethkingia meningoseptica?
This organism is naturally resistant to chromosomal metallo-beta-lactamase and extended-spectrum beta-lactamase: carbapenems, cephalosporins, aztreonam and colistin have no activity. These drugs should not be reported as susceptible.
Where is Elizabethkingia meningoseptica commonly found?
It is typically associated with neonatal meningitis, icu bacteremia, ventilator-associated pneumonia.
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