Can the detection of IgA anti-Mycoplasma pneumoniae added to IgM increase diagnostic accuracy in patients with infections of the lower respiratory airways?

Table 1 Serological profile for anti-Mycoplasma pneumoniae antibodies in patients with of lower respiratory airway infections

Anti-Mycoplasma pneumoniae antibodies profiles				Patients
Group	IgG	IgM	IgA	n (%)	95%CI
A	Negative	Negative	Negative	821 (76.9%)	74.37-79.43
B	Positive	Negative	Negative	143 (13.4%)	11.36-15.44
C	Negative	Positive	Negative	40 (3.7%)	2.57-4.83
D	Negative	Negative	Positive	21 (2.0%)	1.16-2.84
E	Positive	Positive	Negative	13 (1.2%)	0.55-1.85
F	Positive	Negative	Positive	16 (1.5%)	0.77-2.23
G	Negative	Positive	Positive	7 (0.7%)	0.20-1.20
H	Positive	Positive	Positive	6 (0.6%)	0.14-1.06

Table 2 Presence of serological markers for anti-Mycoplasma pneumoniae antibodies, divided per age group in patients with infections of the lower airway tract

	Age (yr)
Antibodies	0-10	11-20	21-30	31-40	41-50	51-60	61-70	71-80	> 80
n	91	30	25	48	55	91	155	289	283
IgG	12	7	6	13	10	21	29	42	38
Positive	(13.2%)	(23.3%)	(24.0%)	(27.1%)	(18.2%)	(23.1%)	(18.7%)	(14.5%)	(13.4%)
95%CI	6.25-20.15	8.17-38.43	7.26-40.74	14.53-39.67	8.00-28.40	14.44-31.76	12.56-24.84	10.44-18.56	9.43-17.37
IgM	22	8	3	7	2	5	5	6	8
Positive	(24.2%)	(26.7%)	(12.0%)	(14.6%)	(3.6%)	(5.5%)	(3.2%)	(2.1%)	(2.8%)
95%CI	15.40-33.00	10.87-42.53	0.00-24.74	4.61-24.59	0.00-8.52	0.82-10.18	0.43-5.97	0.45-3.75	0.88-4.72
IgA	6	3	1	2	0	5	5	14	14
Positive	(6.6%)	(10.0%)	(4.0%)	(4.2%)	(0%)	(5.5%)	(3.2%)	(4.8%)	(4.9%)
95%CI	1.50-11.70	0.00-20.74	0.00-11.68	0.00-9.87	0.00-0.00	0.82-10.18	0.43-5.97	2.34-7.26	2.38-7.41
IgM and/or IgA	23	8	3	8	2	9	10	18	22
Positive	(25.3%)	(26.7%)	(12.0%)	(16.7%)	(3.6%)	(9.9%)	(6.5%)	(6.2%)	(7.8%)
95%CI	16.37-34.23	10.87-42.53	0.00-24.74	6.15-27.25	0.00-8.52	3.76-16.04	2.62-10.38	3.42-8.98	4.68-1.92

Table 3 Increase of diagnosis divided per age group adding search of IgA to IgM, compared to cases that can be diagnosed considering IgM alone

	Age (yr)
Antibodies	0-10	11-20	21-30	31-40	41-50	51-60	61-70	71-80	> 80
n	91	30	25	48	55	91	155	289	283
IgM without IgA	17 (18.7%)	5 (16.7%)	2 (8.0%)	6 (12.5%)	2 (3.6%)	4 (4.4%)	5 (3.2%)	4 (1.4%)	8 (2.8%)
95%CI	10.69-26.71	3.35-30.05	0.00-18.63	3.14-21.86	0.00-8.52	0.19-8.61	0.43-5.97	0.05-2.75	0.88-4.72
IgA without IgM	1 (1.1%)	0 (0%)	0 (0%)	1 (2.1%)	0 (0%)	4 (4.4%)	5 (3.2%)	12 (4.1%)	14 (4.9%)
95%CI	0.00-3.24	0.00-0.00	0.00-0.00	0.00-6.16	0.00-0.00	0.19-8.61	0.43-5.97	1.81-6.39	2.38-7.41
IgM plus IgA	5 (5.5%)	3 (10.0%)	1 (4.0%)	1 (2.1%)	0 (0%)	1 (1.1%)	0 (0%)	2 (0.7%)	0 (0%)
95%CI	0.82-10.18	0.00-20.74	0.00-11.68	0.00-6.16	0.00-0.00	0.00-3.24	0.00-0.00	0.00-1.66	0.00-0.00
Increase of diagnosis	1.1%	0%	0%	2.1%	0%	4.4%	3.2%	4.1%	4.9%
95%CI	0.00-3.24	0.00-0.00	0.00-0.00	0.00-6.16	0.00-0.00	0.19-8.61	0.43-5.97	1.81-6.39	2.38-7.41