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Indian J Med Microbiol. 2018 Oct-Dec;36(4):504-507. doi: 10.4103/ijmm.IJMM_18_274.

Validation of pneumococcal iron acquisition (piaA) gene for accurate identification of Streptococcus pneumoniae.

Author information

1
Department of Microbiology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India.
2
Department of Medicine, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India.
3
Department of Pediatrics, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India.
4
Department of Neonatology, Jawaharlal Institute of Postgraduate Medical Education and Research, Puducherry, India.

Abstract

Purpose:

The pneumococcal iron acquisition (piaA) gene is found to be highly specific and hence proposed as a diagnostic marker for identification of pneumococci. The objective of the present study was to evaluate the piaA gene as a genetic marker for the identification of pneumococci.

Methods:

Twenty isolates were initially sequenced for lytA gene using published primers. PiaA-PCR (piaA polymerase chain reaction) was performed using in-house primers and protocol. Based on the sensitivity and specificity results, a final sample of 30 pneumococcal isolates and 11 non-pneumococcal isolates confirmed with lytA- sequencing were selected. Statistical analyses were performed using OpenEpi v3.01 and GraphPad Quickcalc at P < 0.05 as the level of statistical significance.

Results:

Of the initial 20 samples tested, piaA PCR was positive in only 71.43% (10/14) of the pneumococcal isolates but was 100% specific (0/6 non-pneumococcal isolates) P = 0.011. When the PCR was performed on 41 samples, the sensitivity increased to 73.33% (95% of confidence interval [CI] = 55.55-85.82) and specificity remained the same P < 0.001. The level of agreement between the PCR and lytA-sequencing was found to be moderate (κ = 0.694; 95% CI = 0.432-0.955).

Conclusions:

PiaA-PCR can be used as a specific marker for the identification of pneumococcus, though it is less sensitive. As the level of agreement was moderate, further analyses on a large number of samples can give conclusive evidence for its use as a diagnostic marker for pneumococcus.

KEYWORDS:

LytAgene; Streptococcus pneumoniae; pneumococcal iron acquisition gene; polymerase chain reaction

PMID:
30880696
DOI:
10.4103/ijmm.IJMM_18_274

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