McRAPD unlike MALDI-TOF MS is a suitable candidate for routine discrimination of new Haemophilus influenzae strain acquisition in chronic obstructive pulmonary disease (COPD) and cystic fibrosis

Biomed Pap Med Fac Univ Palacky Olomouc Czech Repub. 2016 Dec;160(4):503-511. doi: 10.5507/bp.2016.050. Epub 2016 Oct 6.


Background and aims: Haemophilus influenzae new strain acquisition has been demonstrated to increase the relative risk of acute exacerbation fourfold in contrast to colonisation or chronic infection by the same strain in chronic obstructive pulmonary disease (COPD). Unfortunately, molecular typing techniques are not suitable for routine use due to cost, labour-intensity and need for special expertise. We tested two techniques potentially useful for routine typing, namely the newly available MALDI-TOF MS and the modified McRAPD compared to MLST as the gold standard.

Methods: In 10 patients (10.8%) suffering from COPD or cystic fibrosis, H. influenzae isolates were recovered repeatedly at different timepoints from the same patient during the study period. This allowed for thirteen pairwise comparisons of typing results in isolates recovered consecutively from the same patient to test the ability of the techniques to uncover new strain acquisition.

Results: MLST detected 9 cases of new strain acquisition among the 13 pairwise comparisons. However, MALDI-TOF MS reported all 13 pairs as different and thus new. In contrast, McRAPD was able to differentiate all the new strain acquisitions from pre-existing ones, both by visual inspection of melting profiles and by Relative Significant Difference values.

Conclusions: Unlike MALDI-TOF MS, McRAPD appears to be a suitable candidate for routine discrimination of new strain acquisitions because of its accuracy and, rapid, easy and economic performance.

Keywords: Haemophilus influenzae; MALDI-TOF MS typing; McRAPD typing; chronic obstructive pulmonary disease; cystic fibrosis; high resolution melting analysis.

Publication types

  • Evaluation Study

MeSH terms

  • Bacterial Typing Techniques / methods
  • Bacterial Typing Techniques / standards
  • Cystic Fibrosis / diagnosis*
  • Diagnosis, Differential
  • Haemophilus Infections / diagnosis*
  • Haemophilus influenzae / isolation & purification*
  • Humans
  • Pulmonary Disease, Chronic Obstructive / diagnosis*
  • Sensitivity and Specificity
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / methods
  • Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / standards