Prevalence of C. trachomatis, U. urealyticum and M. hominis urogenital infection
A total of 5164 of infertile patients (1554 women and 3610 men) were enrolled in the study. The overall prevalence of urogenital C. trachomatis, U. urealyticum and M. hominis detection in the total population was 5.3%, 22.8% and 7.4%, respectively (Table 1). Interestingly, U. urealyticum infection showed a remarkably higher overall prevalence than the others uropathogens analyzed. The prevalence of C. trachomatis infection was significantly higher in men than in women (5.8% versus 4.3%, p=0.034; Tables 1 and 2). Conversely, we found a significantly higher prevalence of both U. urealyticum and M. hominis infection in women (31.1 and 12.1, respectively) than in men (19.2 and 5.3%, respectively) (p<0.001 and p<0.001; Tables 1 and 2).
Table 1. Prevalence of urogenital infections in infertile patients
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Total
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Women
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Men
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(n=5164)
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(n=1554)
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(n=3610)
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Chlamydia trachomatis, n (%)
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275 (5.3%)
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67 (4.3%)
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208 (5.8%)
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Ureaplasma urealyticum, n (%)
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1176 (22.8%)
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484 (31.1%)
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692 (19.2%)
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Mycoplasma hominis, n (%)
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380 (7.4%)
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88 (12.1%)
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192 (5.3%)
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Table 2. Prevalence of infections in infertile patients according to sex and age
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Patients
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C. trachomatis infection
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U. urealyticum infection
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M. hominis infection
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Variables
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n
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n (prevalence)
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Odds ratio
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95% CI
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p
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n (prevalence)
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Odds ratio
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95% CI
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p
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n (prevalence)
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Odds ratio
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95% CI
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p
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Sex
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Women
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1554
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67 (4.3%)
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1.00 (ref.)
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484 (31.1%)
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1.00 (ref.)
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188 (12.1%)
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1.00 (ref.)
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Men
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3610
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208 (5.8%)
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1.36
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1.02-1.80
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0.034 *
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692 (19.2%)
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0.52
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0.46-0.60
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<0.001 *
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192 (5.3%)
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0.41
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0.33-0.50
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<0.001 *
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Age (y.o.)
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Women
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> 40
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355
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17 (4.8%)
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1.00 (ref.)
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107 (30.1%)
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1.00 (ref.)
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43 (12.1%)
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1.00 (ref.)
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40 - 25
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1130
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47 (4.2%)
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0.94
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0.50-1.78
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0.847
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341 (30.2%)
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0.88
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0.66-1.17
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0.372
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135 (11.9%)
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0.80
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0.55-1.19
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0.275
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< 25
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69
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3 (4.3%)
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0.96
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0.26-3.50
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0.949
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36 (52.2%)
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2.27
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1.33-3.89
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0.003*
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10 (14.5%)
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1.04
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0.49-2.22
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0.910
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Men
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> 40
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1356
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88 (6.5%)
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1.00 (ref.)
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233 (17.2%)
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1.00 (ref.)
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72 (5.3%)
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1.00 (ref.)
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40 - 25
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2161
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106 (4.9%)
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0.71
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0.52-0.95
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0.021*
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433 (20.0%)
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1.26
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1.04-1.51
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0.016*
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116 (5.4%)
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1.03
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0.75-1.41
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0.863
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< 25
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93
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14 (15.1%)
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2.51
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1.40-4.48
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0.002*
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26 (28.0%)
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1.66
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1.04-2.66
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0.034*
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4 (4.3%)
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0.72
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0.26-2.02
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0.532
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Univariate analysis. 95%CI: 95% confident interval. A *p<0.05 was considered statistically significant.
Associations among C. trachomatis, U. urealyticum and M. hominis urogenital infections
When assessing the co-infection between C. trachomatis and U. urealyticum, no significant association was found in either infertile women (OR: 1.62, 95% CI: 0.99-2.69, p˃0.05) or men (OR: 1.07, 95% CI: 0.76-1.52, p˃0.05) (Figure 1a, d). In fact, a similar prevalence of U. urealyticum was found in C. trachomatis infected (41.8%, 28/67) and C. trachomatis non-infected (30.7%, 456/1487) women (Figure 1a, Table 3). In addition, a comparable prevalence of U. urealyticum were found in C. trachomatis infected (20.2%, 42/208) and C. trachomatis non-infected (19.1%, 650/3402) men (Figure 1d, Table 3).
Table 3. C. trachomatis, U. urealyticum and M. hominis co-infections in infertile patients
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C. trachomatis
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M. hominis
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Women
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Men
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Women
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Men
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Positive
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Negative
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Positive
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Negative
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Positive
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Negative
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Positive
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Negative
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(n=67)
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(n=1487)
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(n=208)
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(n=3402)
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(n=188)
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(n=1366)
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(n=192)
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(n=3418)
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U. urealyticum
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Positive n (%)
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28 (41.8%)
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456 (30.7%)
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42 (20.2%)
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650 (19.1%)
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171 (90.9%) *
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313 (22.9%)
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178 (92.7%) *
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514 (15.0%)
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Negative n (%)
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39 (58.2%)
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1031 (69.3%)
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166 (79.8%)
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2752 (80.9%)
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17 (9.1%)
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1053 (77.1%)
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14 (7.3%)
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2904 (85.0%)
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M. hominis
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Positive n (%)
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12 (17.9%)
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176 (11.8%)
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14 (6.7%)
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178 (5.2%)
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-
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-
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-
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-
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Negative n (%)
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55 (82.1%)
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1311 (88.2%)
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194 (93.3%)
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3224 (94.8%)
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-
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-
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-
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-
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Univariate analysis. 95%CI: 95% confident interval. A *p<0.05 was considered statistically significant.
Likewise, there was no significant association between C. trachomatis and M. hominis infections in either women (OR: 1.63, 95% CI: 0.83-3.07, p˃0.05) or men (OR: 1.31, 95% CI: 0.75-32.24, p˃0.05) (Figure 1b, e). From the 67 women infected with C. trachomatis, 12 were positive for M. hominis (17.9%), whereas 176 out of the 1487 C. trachomatis-negative women were positive for M. hominis (11.8%) (Figure 1b, Table 3). Also, a comparable prevalence of M. hominis was found in either C. trachomatis infected (6.7%, 14/208) or C. trachomatis non-infected (5.2%, 178/3402) men (Figure 1e, Table 3).
Interestingly, a significant association between M. hominis and U. urealyticum infection was found in women (OR: 33.84, 95% CI: 20.25-56.86, p<0.0001) as well as in men (OR: 71.83, 95% CI: 41.89-187.10, p<0.0001) (Figure 1c, Table 3). As detailed in Table 3, from the 188 women positive for M. hominis, 171 (91.0%) were positive for U. urealyticum. Similarly, a significantly increased prevalence of U. urealyticum (92.7%) was found in M. hominis positive men (Figure 1f). In fact, from the 192 men positive for M. hominis detection, 178 (92.7%) were positive for U. urealyticum (Table 3). Multivariate regression analysis further confirmed these tight associations, indicating that U. urealyticum and M. hominis act as mutual risk factors of infection either in women or men (Supplementary Table S1).
Noteworthy, only 2.0% of infected women (11 out of 539) and 1.5% of infected men (13 out of 871) were co-infected with the three uropathogens analyzed (Supplementary Figure S1).
Demographic parameters associated to C. trachomatis, U. urealyticum and M. hominis infection
Remarkably, C. trachomatis, U. urealyticum and M. hominis infections were significantly associated with patient sex and age (Table 2). In fact, univariate regression analysis revealed that C. trachomatis infection was more likely to be detected in infertile men than in women with an odds ratio of 1.36 (95% CI: 1.02-1.80, p=0.034) (Table 2). Moreover, a significant association was particularly found between C. trachomatis infection and men younger than 25 years (OR: 2.51, 95% CI: 1.40-4.48, p=0.002, Table 2) indicating that men, and especially those younger than 25 years, are at higher risk of infection than women (Table 2). Multivariate analysis further confirmed these associations (Supplementary Table S1).
On the contrary, U. urealyticum and M. hominis infections were associated to females, since men were less likely at risk of U. urealyticum and M. hominis infection than women with odds ratios of 0.52 (95% IC: 0.46-0.60, p<0.001, Table 2) and 0.41 (95% CI: 0.33-0.50, p<0.001, Table 2), respectively. In addition, when analyzing the association of infection with patient sex and age, it was found that U. urealyticum was more prevalent in patients younger than 25 years, either in women or men (OR: 2.27, 95% CI: 1.33-3.89, p=0.003, and OR: 1.66, 95% CI: 1.04-2.66, p=0.034, respectively; Table 2). Multivariate analysis further confirmed these data (Supplementary Table S1).
These results indicate that C. trachomatis, U. urealyticum and M. hominis urogenital infections are associated with patient sex and age. In fact, individuals younger than 25 years at the highest risk of C. trachomatis and U. urealyticum infection. Moreover, our data show that men are at higher risk of C. trachomatis infection and, conversely, women are at higher risk of U. urealyticum and M. hominis infection.