Identification of Non-fermenters by Matrix Assisted Laser Desorption/Ionisation- Time of Flight Mass Spectrometry: Case Series of Achromobacter Infections

Abstract

Achromobacter is a non-fermenting Gram Negative Bacillus (GNB) belonging to the family Alcaligenaceae. It is emerging as a pathogen, causing myriad of infections in different patient groups. Often wrongly identified by conventional microbiological techniques, Achromobacter when recovered from clinical specimens have often been discarded as contaminants. Accurate species identification of the currently known 21 species of Achromobacter, is difficult, labour-intensive and time consuming. Automation has made it possible to reliably and correctly identify Achromobacter species and other non-fermenters. Matrix Assisted Laser Desorption Ionisation-Time Of Flight-Mass Spectrometry (MALDI-TOF-MS) is a boon as it rapidly and accurately identifies Achromobacter species in clinical specimens. Three cases of Achromobacter infection, highlighting the pathogenic potential of the bacteria and the role of automation in its identification are presented with due consent from relatives or patient themselves. This case series highlights that Achromobacter when recovered from clinical specimens should not be discarded as contaminants especially if isolated repeatedly. Case one was a patient who had developed pyelonephritis and sepsis, associated with bacteraemia and ended fatally, Achromobacter was recovered on two occasions from the blood culture. Case two was a patient who was diagnosed of acute pancreatitis with an infected peripancreatic collection who recovered with prolonged therapy, Achromobacter was repeatedly isolated from the pus draining from the peripancreatic collection. Case three was a patient with an infected malignant ulcer with purulent discharge from the swelling. In all three cases Achromobacter was isolated and identified by MALDI-TOF-MS.

Keywords

• achromobacter xylosoxidans/denitrificans
• acute pancreatitis
• bacteraemia
• pyelonephritis
• urosepsis