TABLE 1

Number of staphylococcal strains included and results of evaluation the Xpert MRSA Gen 3 PCR assay

Isolate (n)aResults of Xpert MRSA Gen 3 PCR assay
No. (% agreement) of isolates testedInterpretation as MRSA (no. [%])b
mecA and/or mecCSCCmec-orfX
PositiveNegativePositiveNegative
MRSA
    mecA-positive MRSA (150)c150 (100.0)0147 (98.0)3 (2.0)d147 (98.0)
    mecC-positive MRSA (10)e10 (100.0)010 (100.0)010 (100.0)
    Total (160)160 (100.0)0157 (98.1)3 (1.9)157 (98.1)
MSSA (98)f098 (100.0)27 (28.1)69 (71.9)0
MR-CoNS (25)g25 (100.0)0025 (100.0)0
MS-CoNS (25)g025 (100.0)025 (100.0)0
  • a MRSA, methicillin-resistant S. aureus; MSSA, methicillin-susceptible S. aureus; MR-CoNS, methicillin-resistant coagulase-negative staphylococci; MS-CoNS, methicillin-susceptible coagulase-negative staphylococci.

  • b Interpretation of the assay results and categorization as MRSA as given by the manufacturer: MRSA detected, both SCCmec-orfX and mecA and/or mecC targets tested positive; MRSA not detected, one or both of the SCCmec-orfX and mecA and/or mecC targets tested negative.

  • c Including more frequently encountered (t001, t002, t003, t004, t011, t008, t014, t020, t022, t024, t032, t034, t045, t264, t463, t1227, t2373, t4217, t4881, and t8374, each n = 6) and rarely occurring (t012, t015, t030, t037, t038, t041, t044, t063; t114, t127, t151, t223, t318, t379, t437, t481, t504, t535, t578, t634, t651, t785, t849, t1107, t1282, t2369, t4417, t6736, t7391, and t8380, each n = 1) MRSA spa types in Germany. SCCmec types I (n = 7), II (n = 57), III (n = 2), IV (n = 70) and V (n = 13) were detected; one isolate was nontypeable.

  • d The raw reads of the three isolates (RUO83 [t004], RUO140 [t003], and RUO159 [t004]) were submitted to the European Nucleotide Archive (http://www.ebi.ac.uk/ena/) under the study accession no. PRJEB10686.

  • e Comprising spa types t843 (n = 5), t978, t1773, t5930, t7189, and t7603.

  • f Includes 4 known SCCmec remnant strains and 10 isolates giving false-positive results in the previous version of the Xpert MRSA Gen PCR assay.

  • g Comprising 30 clinical Staphylococcus strains (S. capitis subsp. capitis, n = 1; S. epidermidis, n = 10; S. haemolyticus, n = 10; S. hominis subsp. hominis, n = 8; and S. warneri, n = 1) and 20 type and reference strains (S. auricularis DSM 20609; S. cohnii subsp. cohnii DSM 20260; S. cohnii subsp. urealyticus DSM 6718; S. haemolyticus DSM 20263 and DSM 20264; S. hominis subsp. hominis DSM 20320, DSM 20328, and DSM 20329; S. hominis subsp. novobiosepticus ATCC 700236; S. hyicus DSM 20459; S. lugdunensis DSM 4804, DSM 4805, and DSM 6670; S. saprophyticus subsp. saprophyticus DSM 20229 and DSM 20289; S. schleiferi subsp. schleiferi DSM 6628; S. sciuri subsp. sciuri DSM 20345; S. simulans DSM 20322; S. warneri DSM 20316; and S. xylosus DSM 6179).