Table 1. Mutations in the mucA gene of mucoid isolates from strains MPA, MPA-T1, MPA-T2 and MPA-T3.

Strain and mucA mutationa	Stopb	Number of isolates
MPA
ΔG at 426	TGA at 440	6
C→T at 424	TAG at 424	1
C→T at 436	TAG at 436	1
None	none	3
MPA-T1
ΔC at 362	TGA at 385	1
G→A at 249	TGA at 247	1
C→T at 367	TAG at 367	1
C→T at 424	TAG at 424	1
C→T at 505	TAG at 505	1
none	none	9
MPA-T2
ΔC at 431	TGA at 440	12
none	none	1
MPA-T3
ΔG at 426	TGA at 440	5
ΔC at 431	TGA at 440	10

^aΔG at 426 corresponds to a −1 bp deletion within G⁵SSR₄₂₆; ΔC at 362 corresponds to a −1 bp deletion within a mononucleotide SSR of four Cs from 362 to 365 (C⁴SSR₃₆₂); ΔC at 431 corresponds to a −1 bp deletion within C⁶SSR₄₃₁. “None” refers to conversion to mucoidy occurring in the absence of mucA mutations. The nature of these non-mucA alterations leading to a mucoid phenotype was not investigated in this work.

^bStop codon produced at the site of the mutation by substitutions or placed in frame by frameshift mutations.