Legionella Speciation

MALDI_TOFMALDI-TOF (Matrix Assisted Laser Desorption Ionization /Time of Flight) uses the proteomic fingerprint of the microorganism for its identification compared to fingerprinting using Sequencing. For microbiological applications mainly TOF mass analyzers are used. During MALDI-TOF analysis, the m/z ratio (mass-to-charge ratio) of an ion is measured by determining the time required for it to travel the length of the flight tube. Based on the TOF information, a characteristic spectrum called peptide mass fingerprint (PMF) is generated for analytes in the sample.

The MALDI-TOF gives faster with higher sensitivity results compared to biochemical manual methods. The MALDI-TOF can be used to speciate isolates from samples sent to Aerobiology or pure cultures of Legionella can be submitted to the Virginia location for speciation

qPCR Testing

Real time qPCR is a rapid molecular method used to detect and quantitate Legionella pneumophila and Legionella species in potable and non-potable water.

If Legionella DNA is present it will be amplified and detected using fluorescence tagged to the Legionella gene. The concentration is compared to a standard curve and results are calculated and reported as low, moderate and high GU – Genomic Units. Genomic Units cannot be directly correlated to CFU because PCR reports live Legionella , dead Legionella and non-culturable Legionella .

Advantages:

  • Outbreak investigations
  • 6-48 hours turnaround time
  • No confirmation needed
  • Smaller sample size – 120 mL
  • Potable and Non-Potable water

CDC Culture Method

The CDC culture method is used for processing both potable and non-potable samples. Potable waters are concentrated and non-potable waters such as cooling towers are acid treated to remove background bacteria and isolate Legionella. Detects L. pneumophila Serogroup 1, L. pneumophila Serogroup 2-15 and Legionella species in 7-10 days. Please use 1 Liter or 250 mL sterile sample bottles with preservative. Include 3-5 mL water sample with swabs from the same location.

Legiolert

Legioler_IDEXX The Legiolert test detects Legionella pneumophila in water samples. This test is based on a bacterial enzyme detection technology that signals the presence of Legionella pneumophila through utilization of a substrate present in the Legiolert reagent. Legionella pneumophila cells grow rapidly and reproduce using the rich supply of aminoacids, vitamins, and other nutrients present in the Legiolert reagent.

Ideal for routine monitoring:

  • Hold time is 30 hours
  • Confirmed results without additional tests
  • Detects and quantifies Legionella pneumophila
  • Smaller sample size of 100 mL
  • Quicker TAT, results in 7 days
  • Identify ‘hot’ towers faster

Legionella pneumophila in water, and is a non-culturable method with results in 7 days. Detection limit for qualitative result is 1cfu/100 mL and for Quanti-tray method. The detection limit for potable water is >10 cfu /100 mL and non-potable water is >1000 cfu /100 mL.