Bacterial vaginosis associated with high rates of sexually transmitted infections among South African adolescent girls and young women.

A total of 212 AGYW were retrospectively recruited from the Eastern Cape HPV education intervention study. The median age of study participants was 18 years, with an interquartile range (IQR) of 18–20 years. The majority of study participants were between the ages of 17–19 years (64.6%, 137/212), followed by the 20–23 age group (26.4%, 56/212) and the 15–16 years age group (9.0%, 19/212). A high proportion of the study population was not smoking (82.5%, 175/212) but had drunk alcohol in their lifetime (82.1%, 174/212). The sexual debut median of participants was 16 years, with a 15–17 years IQR. The majority of study participants reported not using condoms during their last sexual intercourse (61.6%, 122/198). However, only 27.6% (53/192) of study participants reported condoms as their current contraceptive method used by them or their partner. A proportion of 21.7% (46/212) have been pregnant in their lifetime. Approximately 31.1% (66/212) of the study population had unknown HIV status, 65.6% (139/212) were HIV-negative, and 3.3% (7/212) were HIV-positive (Table  1 ). The majority of Eastern Cape province AGYW (176/212, 83.0%) were infected with one or more of the detected STIs (HPV, C. trachomatis , N. gonorrhoeae , T. vaginalis , M. genitalium or HSV1/2). A proportion of 40.6% (86/212) were infected with one of the detected STIs, while 33.5% (71/212) were infected with two of the detected STIs, 9.0% (19/212) with three to four of the detected STIs and only 17.0% (36/212) were not infected with any of the detected STIs (Fig.  1 ). Among the STIs detected, HPV was the most dominant STI (75.9%, 161/212) detected, followed by C. trachomatis (29.2%, 62/212), N. gonorrhoeae (11.8%, 25/212), T. vaginalis (9.4%, 20/212), M. genitalium (6.6%, 14/212) and HSV1/2 (6.6%, 14/212). All HSV1/2 and M. genitalium cases in AGYW presented as multiple infection (co-infected with one or more of the detected STIs). In 42.5% (90/212) AGYW, these STIs presented as multiple infection, in which the three most common coinfections were HPV and C. trachomatis coinfection (23.6%, 95% CI: 18.4–29.8), HPV and N. gonorrhoeae (9.0%, 95% CI: 5.8–13.6), and C. trachomatis and N. gonorrhoeae (7.1%, 95% CI: 4.5–11.4, Table  2 ). Table 1 Characteristics of AGYW who participated in the study Variables % n / N Age (years) 18 (18–20 years)  15–16 9.0 19/212  17–19 64.6 137/212  20–23 26.4 56/212 Ever smoked  Yes 17.5 37/212  No 82.5 175/212 Tried to drink alcohol  Yes 82.1 174/212  No 17.9 38/212 Sexual debut , median IQR 16 (15–17 years)  ≤ 15 years old 39.8 84/211  16 years old 32.7 69/211  ≥ 17 years old 27.5 58/211 Lifetime sexual partners  1 person 25.3 50/198  2 people 39.9 79/198  3 people 18.2 36/198  ≥ 4 people 16.7 33/198 Past 3-month sexual partners  0 16.2 32/198  1 person 71.2 141/198  2–4 people 12.6 25/198 Drunk during last intercourse  Yes 6.1 12/198  No 93.9 186/198 Condom use during last intercourse  Yes 38.4 76/198  No 61.6 122/198 Contraceptives currently used by participant and/or partner  No method 26.0 50/192  Birth control pills 6.8 13/192  Condom 27.6 53/192  Intrauterine devices 1.0 2/192  3-month injectable (Depo-Provera) 21.4 41/192  2-month injectable (Nur-Isterate) 14.6 28/192  Unknown injectable 2.6 5/192 Vaginal sex past 1 month , median (IQR) 2 (1–3) Ever pregnant  Yes 21.7 46/212  No 78.3 166/212 HIV Status  Positive 3.3 7/212  Negative 65.6 139/212  Unknown 31.1 66/212 Characteristics of AGYW who participated in the study Contraceptives currently used by participant and/or partner Fig. 1 Patterns of sexually transmitted infections among AGYW of Eastern Cape Province, South Africa. HPV: Human papillomavirus, CT: C. trachomatis , NG: N. gonorrhoeae , TV: T. vaginalis , MG: M. genitalium . HSV1/2: Herpes simplex virus 1/2 Patterns of sexually transmitted infections among AGYW of Eastern Cape Province, South Africa. HPV: Human papillomavirus, CT: C. trachomatis , NG: N. gonorrhoeae , TV: T. vaginalis , MG: M. genitalium . HSV1/2: Herpes simplex virus 1/2 Table 2 Single and multiple sexually transmitted infections prevalence among AGYW of Eastern Cape Province, South Africa Infected with HPV C. trachomatis N . gonorrhoeae T. vaginalis M. genitalium HSV1/2 n , % (95% CI), n n , % (95% CI) n , % (95% CI) n , % (95% CI) n , % (95% CI) % (95% CI), n Overall 161, 75.9 (69.7–81.2) 62, 29.2 (23.5–35.7) 25, 11.8 (8.1–16.9) 20, 9.4 (6.1–14.2) 14, 6.6 (3.9–10.9) 14, 6.6 (3.9–10.9) Single infection 79, 37.6 (31.0-43.9) 5, 2.4 (1.0-5.4) 1, 0.5 (0.0-2.6) 5, 2.4 (1.0-5.4) 0, 0.0 (0.0-1.8) 0, 0.0 (0.0-1.8) Multiple infection 82, 38.7 (32.4–45.4) 57, 26.9 (21.4–33.2) 24, 11.3 (7.7–16.3) 15, 7.1 (4.3–11.3) 14, 6.6 (3.9–10.8) 14, 6.6 (3.9–10.8) Co-infected with HPV … 50, 23.6 (18.4–29.8) 19, 9.0 (5.8–13.6) 13, 6.1 (3.5–10.3) 13, 6.1 (3.5–10.3) 13, 6.1 (3.5–10.3) C. trachomatis 50, 23.6 (18.4–29.8) … 15, 7.1 (4.5–11.4) 6, 2.8 (1.2–6.2) 4, 1.9 (0.6–4.9) 5, 2.4 (0.9–5.6) N. gonorrhoeae 19, 9.0 (5.8–13.6) 15, 7.1 (4.5–11.4) … 4, 1.9 (0.6–4.9) 1, 0.5 (< 0.0-2.9) 2, 0.9 (0.0-3.6) T. vaginalis 13, 6.1 (3.5–10.3) 6, 2.8 (1.2–6.2) 4, 1.9 (0.6–4.9) … 1, 0.5 (< 0.0-2.9) 1, 0.5 (< 0.0-2.9) M. genitalium 13, 6.1 (3.5–10.3) 4, 1.9 (0.6–4.9) 1, 0.5 (< 0.0-2.9) 1, 0.5 (< 0.0-2.9) … 1, 0.5 (< 0.0-2.9) HSV1/2 13, 6.1 (3.5–10.3) 5, 2.4 (0.9–5.6) 2, 0.9 (0.0-3.6) 1, 0.5 (< 0.0-2.9) 1, 0.5 (< 0.0-2.9) … Single and multiple sexually transmitted infections prevalence among AGYW of Eastern Cape Province, South Africa Table 3 Patterns of sexually transmitted infections according to bacterial vaginosis status among AGYW of Eastern Cape Province, South Africa STI Negative 1 STI 2 STIs 3–4 STIs n % n % PR (95% CI) p -value n % PR (95% CI) p -value n % PR (95% CI) p -value BV-positive, N  = 94 13 13.8 33 35.1 ref 34 36.2 ref 19 20.2 ref BV-intermediate, N  = 26 7 26.9 9 34.6 0.99 (0.52–1.69) > 0.999 9 34.6 0.96 (0.51–1.63) 0.884 1 3.8 0.19 (0.03–0.99) 0.048 BV-negative, N  = 92 16 17.4 44 47.8 1.36 (0.97–1.94) 0.101 28 30.4 0.84 (0.56–1.26) 0.407 4 4.3 0.22 (0.08–0.57) 0.001 BV-negative with sign. Lactobacillus spp. N  = 65 11 16.9 37 56.9 1.62 (1.15–2.30) 0.009 18 27.7 0.77 (0.47–1.21) 0.263 1 1.5 0.08 (0.01–0.42) 0.001 Detected STIs include HPV, C. trachomatis , N. gonorrhoeae , T. vaginalis , M. genitalium and HSV1/2 Patterns of sexually transmitted infections according to bacterial vaginosis status among AGYW of Eastern Cape Province, South Africa Detected STIs include HPV, C. trachomatis , N. gonorrhoeae , T. vaginalis , M. genitalium and HSV1/2 Among the Eastern Cape province AGYW, 44.3% (94/212) were BV-positive, 12.3% (26/212) were BV-intermediate, and 43.4% (92/212) were BV-negative. Among the BV-negative group, 70.7% (65/92) had a significant amount of Lactobacillus species ( L. crispatus , L. gasseri or L. jensenii ), while 29.3% (27/95) had low levels of Lactobacillus species. Table  3 presents the patterns of STIs according to bacterial vaginosis status among AGYW. BV-negative AGYW with a significant amount of Lactobacillus species were more likely to have one (1) STI than the BV-positive women (PR: 1.62, 95% CI: 1.15–2.30, p  = 0.009). BV-negative AGYW had a significantly lower prevalence of having 3–4 STIs than BV-positive AGYW (PR: 0.22, 95% CI: 0.08–0.57, p  = 0.001); in addition, the prevalence of having 3–4 STIs was further decreased when the analysis focused on BV-negative AGYW with a significant amount of Lactobacillus species (PR: 0.08, 95% CI: 0.01–0.42, p  = 0.001, Table  3 ). It was interesting to note that among BV-negative individuals, having a significant amount of Lactobacillus species was associated with a reduced prevalence of having 3–4 STIs than having low levels of Lactobacillus species (PR: 0.14, 95% CI: 0.02–0.93, p  = 0.04). Lactobacillus species prevalence was significantly higher among the BV-negative women than the BV-positive women (79.3%, 73/92; 6.4%, 6/94; p  < 0.001, respectively). It is important to note that the BV-positive women with Lactobacillus species were found to have low levels of Lactobacillus species (quantitative thresholds range of between 1.79 and 3.34). Compared to BV-negative women, the BV-positive women had significantly higher prevalence of bacterial vaginosis–associated bacteria-2 (7.6%, 7/92; 75.5%, 71/94; p  < 0.001, respectively); Atopobium vaginae (0.0%, 0/92; 89.4%, 84/94; p  < 0.001, respectively); Megasphaera Type 1 (5.5%, 5/92; 68.1%, 64/94, p  < 0.001, respectively), Mobiluncus spp. (29.3%, 27/92; 84.0%, 79/94; p  < 0.001, respectively) and Gardnerella vaginalis (81.5%, 75/92; 97.9%, 92/94; p  < 0.001, respectively). It is interesting to note that the prevalence of Gardnerella vaginalis was significantly higher among BV-positive women than BV-negative with significant amount of Lactobacillus species (97.9%, 92/95; 78.5%, 51/65; p  < 0.001), in contrast this was not observed among BV-negative women with low amount of Lactobacillus species (97.9%, 92/94; 88.9%, 24/27; p  = 0.073). Bacteroides fragilis prevalence was not statistically different between the BV-negative and BV-positive women (9.8%, 9/92; 6.4%, 6/94, p  = 0.431 respectively, Fig.  2 ). Fig. 2 Prevalence of Lactobacillus and bacterial vaginosis-associated species among the AGYW of Eastern Cape Province, South Africa Prevalence of Lactobacillus and bacterial vaginosis-associated species among the AGYW of Eastern Cape Province, South Africa To investigate the factors associated with bacterial vaginosis and its impact on STIs, the analysis focused on BV-negative with a significant amount of Lactobacillus species and BV-positive AGYW. Other groups were dropped to avoid possible noise in BV-intermediate and BV-negative with limited Lactobacillus species. Table  4 presents the characteristics of participants who were BV-positive or BV-normal with significant Lactobacillus species. BV-negative AGYW with a significant amount of Lactobacillus species were younger than the BV-positive AGYW, had lower lifetime sexual partners, smoking, and used condoms during their last sexual intercourse. When compared with BV-negatives with significant amount of Lactobacillus species, bacterial vaginosis positive women were more likely to be positive for C. trachomatis (PR: 1.8, 95% CI: 1.0-3.2, p  = 0.028); T. vaginalis (PR: 8.3, 95% C: 1.1–62.3, p  = 0.011) and vaginal discharge or itching (PR: 2.4, 95% CI: 1.2–4.8, p  = 0.013). They were also at increased prevalence of being positive with M. genitalium (PR: 2.4, 95% CI: 0.5–11.3, p  = 0.241), however, it was not statistically significance (Table  5 ). Smoking (PR: 1.6, 95% CI: 1.1–2.4, p  = 0.008), having two (2) lifetime partners (PR: 1.9, 95% CI: 1.2–3.1, p  = 0.006), having three (3) lifetime partners (PR: 2.6, 95% CI: 1.3–5.2, p  = 0.007) and having new past three-month sexually partners (PR: 1.8, 1.2–2.7, p  = 0.005) were the associated factors of bacterial vaginosis positivity (Table  6 ). Table 4 Characteristics of participants who were BV-positive or BV-normal with significant Lactobacillus species Characteristics Total BV-positive BV-normal with sign. Lactobacillus species p -value n n (%) n (%) Age , years  15–16 15 11 73.3 4 26.7 0.002  17–19 102 50 49.0 52 51.0  20–24 42 33 78.6 9 21.4 HIV status; n (%)  Positive 6 6 (100.0) 0 (0.0) 0.085**  Negative 102 63 (61.8) 39 (38.2) Ever smoked; n (%)  Yes 30 12 (40.0) 18 (60.0) 0.023  No 129 82 (63.6) 47 (36.4) Tried to drink alcohol  Yes 129 79 (61.2) 50 (38.8) 0.259  No 30 15 (50.0) 15 (50.0) Sexual debut age , years  ≤ 15 years old 57 36 (63.2) 21 (36.8) 0.481  16 years old 57 30 (52.6) 27 (47.4)  ≥ 17 years old 44 27 (61.4) 17 (38.6) Lifetime sexual partners  1 person 41 16 (39.0) 25 (61.0) 0.006  2 people 51 35 (68.6) 16 (31.4)  3 people 30 23 (76.7) 7 (23.3)  ≥ 4 people 29 17 (58.6) 12 (41.4) Past 3-month sexual partners  0 24 9 (37.5) 15 (62.5) 0.045  1 person 108 70 (64.8) 38 (35.2)  2–4 people 19 12 (63.2) 7 (36.8) Drunk during last intercourse  No 6 3 (50.0) 3 (50.0) 0.682**  Yes 145 88 (61.0) 57 (39.3) Condom used during last intercourse  Yes 59 28 (47.5) 31 (52.5) 0.010  No 92 63 (68.5) 29 (31.5) Contraceptive used  None 40 27 (67.5) 13 (32.5) 0.016**  Birth control pills 13 12 (92.3) 1 (7.7)  Condom 48 23 (47.9) 25 (52.1)  3-month injectable (Depo-Provera) 25 11 (44.0) 14 (56.0)  2-month injectable (Nur-Isterate) 20 14 (70.0) 6 (30.0)  Unknown injectable 2 2 (100.0) 0 (0.0)  None-penetrative sex 1 1 (100.0) 0 (0.0)  Condom and Nuristerate 2 1 (50.0) 1 (50.0) Ever pregnant  Yes 32 19 (59.4) 13 (40.6) 0.974  No 127 75 (59.1) 52 (40.9) Sign.: Significant Characteristics of participants who were BV-positive or BV-normal with significant Lactobacillus species Sign.: Significant Table 5 The impact of bacterial vaginosis on sexually transmitted infections and outcomes among the AGYW of Eastern Cape Province, South Africa Characteristics Total BV-positive BV-normal with significant Lactobacillus spp. PR (95% CI) p -value N % n % Bacterial Vaginosis 159 94 (59.1) 65 (40.9) Any HPV  Positive 129 78 (60.5) 51 (39.5) 1.1 (0.9–1.2) 0.474 #  Negative 30 16 (53.3) 14 (46.7) HR-HPV  Yes 96 62 (64.6) 34 (35.4) 1.3 (1.0–1.7) 0.084 #  No 63 32 (50.8) 31 (49.2) LR-HPV  Yes 70 39 (55.7) 31 (44.3) 0.9 (0.6–1.2) 0.439 #  No 89 55 (61.8) 34 (38.2) C. trachomatis  Positive 47 34 (72.3) 13 (27.7) 1.8 (1.0–3.2) 0.028 #  Negative 112 60 (53.6) 52 (46.4) N. gonorrhoeae  Positive 23 17 (73.9) 6 (26.1) 1.3 (1.0–1.7) 0.119  Negative 136 77 (56.6) 59 (43.4) T. vaginalis  Positive 13 12 (92.3) 1 (7.7) 8.3 (1.1–62.3) 0.011 #  Negative 146 82 (56.2) 64 (43.8) M. genitalium  Positive 9 7 (77.8) 2 (22.2) 2.4 (0.5–11.3) 0.241 #  Negative 150 87 (58.0) 63 (42.0) HSV1/2  Positive 9 6 (66.8) 3 (33.3) 0.7 (0.2–2.8) 0.635 #  Negative 150 88 58.7) 62 (41.3) HIV status  Positive 6 6 (100.0) 0 (0.0) - 0.058 #  Negative 102 63 (61.8) 39 (38.2) Experienced vaginal discharge or itching  No 57 26 (45.6) 31 (54.4) 1 ref  0–7 days 31 24 (77.4) 7 (22.6) 2.4 (1.2–4.8) 0.013*  7–30 days 13 7 (53.8) 6 (46.2) 1.2 (0.6–2.2) 0.612*  1–6 months 23 15 (65.2) 8 (34.8) 1.6 (0.9–2.9) 0.150*  ≥ 6 months 35 22 (62.9) 13 (37.1) 1.5 (0.9–2.4) 0.129* Ever had genital ulcers , blisters or warts  No 123 70 (56.9) 53 (43.1) 1 ref  0–7 days 17 11 (64.7) 6 (35.3) 1.2 (0.6–2.4) 0.562*  7–30 days 7 6 (85.7) 1 (14.3) 3.0 (0.5–18.7) 0.236*  1–6 months 2 2 (100.0) 0 (0.0) 0.9 (0.4–1.8) 0.686*  ≥ 6 months 8 4 (50.0) 4 (50.0) 0.9 (0.4–1.8) 0.686* *Computed using binomial logistics regression; # Computed using Chi-squared statistics, $ Any STI include HIV, HPV, C. trachomatis , N. gonorrhoeae , T. vaginalis , M. genitalium or HSV1/2 The impact of bacterial vaginosis on sexually transmitted infections and outcomes among the AGYW of Eastern Cape Province, South Africa *Computed using binomial logistics regression; # Computed using Chi-squared statistics, $ Any STI include HIV, HPV, C. trachomatis , N. gonorrhoeae , T. vaginalis , M. genitalium or HSV1/2 Table 6 Demographic and sexual behaviour factors associated with bacterial vaginosis positivity among the AGYW of Eastern Cape Province, South Africa  n/N PR 95% CI p -value Age Categories; years 15–16 11/15 1 ref ref 17–19 50/102 0.5 (0.2–1.2) 0.140 20–25 33/42 1.2 (0.4–3.4) 0.674 Ever smoked Yes 12/30 1 ref ref No 82/129 1.6 (1.1–2.4) 0.008 Tried to drink alcohol No 15/30 1 ref ref Yes 79/129 1.3 (0.8–2.0) 0.233 Sexual debut age; years ≤ 15 years old 36/57 1 ref ref 16 years old 30/57 0.8 (0.5–1.2) 0.259 ≥ 17 years old 27/44 1.0 (0.6–1.6) 0.853 Lifetime sexual partners 1 person 16/41 1 ref ref 2 people 35/51 1.9 (1.2–3.1) 0.006 3 people 23/30 2.6 (1.3–5.2) 0.007 ≥ 4 people 17/29 1.5 (0.9–2.4) 0.127 Past 3-month sexual partners 0 9/24 1 ref ref 1 person 70/108 1.8 (1.2–2.7) 0.005 2–4 people 12/19 1.7 (0.9–3.3) 0.119 Drunk during last intercourse No 88/145 1 ref ref Yes 3/6 1.3 (0.6–2.9) 0.568 Condom used during last sexual intercourse Yes 28/59 1 ref ref No 63/92 1.3 (0.6–2.9) 0.568 Contraceptive used None 27/40 1 ref ref Birth control pills 12/13 4.2 (0.6–29.3) 0.144 Condom 23/48 0.6 (0.4–1.1) 0.077 3-month injectable (Depo-Provera) 11/25 0.6 (0.3–1.0) 0.059 2-month injectable (Nur-Isterate) 14/20 1.1 (0.5–2.4) 0.845 Unknown injectable 2/2 1 - - None-penetrative sex 1/1 1 - - Condom and Nuristerate 1/2 Ever pregnant Yes 19/32 1 ref ref No 75/127 1.0 (0.6–1.6) 0.974 Demographic and sexual behaviour factors associated with bacterial vaginosis positivity among the AGYW of Eastern Cape Province, South Africa

The parent study was approved by the Human Research Ethics Committee at the University of Cape Town, South Africa (HREC: 369/2015) and the Eastern Cape Provincial Health Research Committee (EC_2016RP29_562). Written informed consent to participate in the parent study was provided by the age ≥ 18 years participants and the participants’ legal guardians for participants who were less than 18 years old. A written informed assent was also obtained from all study participants who were less than 18 years. The Walter Sisulu University Human Research Ethics Committee (protocol number: 044/2020) approved the sub-study investigating BV and other STIs. This was a retrospective cross-sectional study among adolescent girls and young women (15–23 years) attending high schools who had participated in a parent study known as the HPV Education Intervention Study that was conducted between April and May 2019 [ 19 ]. The parent study aimed at educating the high school attendees on HPV and associated diseases and further investigate HPV and its association. All the recruited adolescent girls and young women were sexually experienced, not menstruating and not pregnant at enrolment. They were recruited from two high schools in Chris Hani District Municipality, Eastern Cape Province of South Africa. Study participants’ recruitment, specimen and data collection were described elsewhere [ 19 , 20 ]. Participants with valid HPV, Chlamydia trachomatis , Neisseria gonorrhoea , Trichomonas vaginalis , Mycoplasma genitalium , herpes simplex virus 1/2 (HSV1/2) and bacterial vaginosis data were recruited. The linked sexual behaviour, smoking habits, alcohol use, contraceptive use and HIV status were also collected. Detailed specimen collection and processing were previously reported by Mbulawa et al., [ 19 ]. Briefly, vaginal specimens were collected using Evalyn ® Brush (Rovers ® Medical Devices B.V., Oss, Netherlands) as per the manufacturer’s provided instruction leaflets. The nucleic acid from each self-collected vaginal specimen was extracted using an automated procedure of MagNA Pure Compact (Roche Molecular Systems, Inc., Branchburg, NJ, USA) and MagNA Pure Compact Nucleic Acid Isolation Kit (Roche Molecular Systems, Inc., Branchburg, NJ, USA), according to the manufacturer’s instructions. HPV in extracted nucleic acid was detected using the Roche Linear Array HPV Genotyping Test (Roche Molecular Systems, Inc., Branchburg, NJ, USA) that detects 37 different HPV genotypes (HPV-6, -11, -16, -18, -26, -31, -33, -35, -39, -40, -42, -45, -51, -52, -53, -54, -55, -56, -58, -59, -61, -62, -64, -66, -67, -68, -69, -70, -71, -72, -73, -81, -82, -83, -84, -89, and IS39) and β-globin gene to monitor sample adequacy, extraction, amplification and hybridization. Chlamydia trachomatis , Neisseria gonorrhoeae , Trichomonas vaginalis and Mycoplasma genitalium were detected using the Allplex™ STI Essential Assay (Seegene Inc., Seoul, Korea). HSV1/2 were detected using the Allplex™ Genital Ulcer Assay (Seegene Inc., Seoul, Korea). To determine bacterial vaginosis status, the Allplex™ Bacterial Vaginosis plus Assay (Seegene Inc., Seoul, Korea) was used. As determined by Nugent scoring (the common BV diagnostic method), the overall BV prevalence was previously reported to be lower than that by Seegene Allplex™ (46.5% compared to 62.0%). The Seegene Allplex™ BV assay and Nugent score pair agreement-index was 79.8% (95% CI, 73.9%−84.7%) and Cohen’s kappa statistic of 0.60 (95% CI 0.55 − 0.68) [ 21 ]. Allplex™ Bacterial Vaginosis plus Assay is a real-time PCR assay that simultaneously amplifies and detects target nucleic acids of Megasphaera Type 1, Lactobacillus species ( L. crispatus , L. gasseri , L. jensenii are detected as a group), Bacteroides fragilis , Gardnerella vaginalis , Bacterial vaginosis–associated bacteria 2, Atopobium vaginae , Mobiluncus species. ( Mobiluncus mulieris , Mobiluncus curtisii ). This assay also automatically interprets bacterial vaginosis as normal with significant number of Lactobacilli spp., normal with less levels of Lactobacilli spp., intermediate, and positive using quantitative analysis with respective Ct values. The BV-normal with appreciable numbers of Lactobacillus spp. quantitative thresholds (log) for Lactobacillus spp. were all between 3.74 and 7.14, while the BV-normal lacking appreciable numbers of Lactobacillus spp. quantitative thresholds (log) for Lactobacillus spp. were between 0.78 and 3.37, as auto detected by the Allplex™ Bacterial Vaginosis Assay. The Allplex™ Assays were all run on a CFX96™ Real-time PCR Detection System (Bio-Rad)—CFX Manager™ Software-IVD v1.6 and CFX96™ Dx System (Bio-Rad)—CFX Manager™ Dx Software v3.1. Seegene Viewer Software (Seegene Inc., Seoul, Korea) was used to interpret data according to the manufacturer’s instructions. The sexual behaviour, age, smoking habits, alcohol use, contraceptive use, bacterial vaginosis status, STIs data for the participants meeting the recruitment criteria were extracted from the main study master database. A database for the current study was created and stored in Microsoft Excel. GraphPad Prism version 8 was used for analysis. For descriptive statistics percentages, median and interquartile range (IQR) were used. Association between prevalence and related categorical variables such as age, grade, number of sexual partners, etc., were analysed using the chi square or Fisher’s exact test depending on the value of expected frequencies. Bivariable relative measures of associations were computed using Chi-squared statistics or binomial logistic regression analyses. Since this was a cross-sectional study and the risk ratio is mathematically similar to the prevalence ratio, the prevalence ratio (PR) is used for reporting the bivariable relative measures of association [ 22 , 23 ]. The results were considered statistically significant if p -value is ≤ 0.05 at the confidence interval (CI) of 95%.

Bacterial vaginosis (BV) is a common dysbiosis of vaginal microorganisms characterized by the decrease of Lactobacilli species and an increase of facultative anaerobic bacteria [ 1 , 2 ]. In a normal vagina flora, around 95.0% of bacteria are Lactobacillus species, and the role of these bacteria is to maintain normal vaginal pH (pH < 4.5), producing antimicrobial compounds (hydrogen peroxide) and modulate immune response against infectious pathogens [ 3 – 5 ]. Among these Lactobacillus species, the Lactobacillus crispatus is reported to be the most optimal. However, they are not dominant in the cervicovaginal microbiota of African women [ 1 , 2 , 6 ]. Bacterial vaginosis is highly prevalent among sub-Saharan African women; it was estimated that 42.1% of women are affected [ 7 ]. Approximately 47.0% of South African adolescent girls and young women (AGYW) were reported to have BV [ 8 ]. In BV-positive women, there is a decrease in Lactobacilli spp. and an increase in anaerobic bacteria, including Prevotella spp., Mycoplasma hominis , Gardnerella vaginalis , Atopobium vaginae , Mobiluncus spp., Bacterial vaginosis associated bacteria and Ureaplasma urealytocus [ 4 ]. Bacterial vaginosis can lead to obstetric and gynaecologic complications which include spontaneous abortion, preterm labour and delivery, subclinical pelvic inflammatory disease, post-caesarean delivery wound infections, premature rupture of membrane, postpartum endometriosis, and postsurgical infections [ 9 , 10 ]. It also increases the risk of infertility and sexually transmitted infections (STIs), including chlamydia, gonorrhoea, human papillomavirus (HPV) and human immunodeficiency virus (HIV) [ 1 , 11 ]. The BV-associated STIs cause minor to major complications like reproductive health problems and cancer development [ 9 , 10 , 12 ]. It is unfortunate that despite these, there has been limited progress in finding an effective cure for BV [ 6 ]. The most dominant risk factors associated with BV include cigarette smoking, douching, multiple sexual partners, use of sex toys, use of intrauterine device contraception, use of antibiotics, drug abuse, STIs, hygiene practice and partner characteristics [ 4 , 13 , 14 ]. AGYW are a key population affected by STIs, it is therefore important to investigate BV prevalence, impact on STI prevalence and its associated factors. STIs contracted during the adolescent years, pose the risk of affecting the sexual and the reproductive health of women sometime later in life [ 15 ]. In 2020, AGYW represented 10.0% of the sub-Saharan African population but accounted for 25.0% of HIV infections [ 16 , 17 ]. Bacterial vaginosis is prevalent in populations that are at high risk of HIV infection, including South Africa [ 18 ]. Bacterial vaginosis is associated with the acquisition of most STIs, including HIV, as well as persistence of STIs. Understanding factors driving BV could contribute to its prevention and ultimately to the decrease of STI acquisition. However, there is no available literature on BV and its association with STIs among AGYW of South Africa’s Eastern Cape province. Therefore, this study aimed to investigate the BV prevalence, its effect on human papillomavirus (HPV), Chlamydia trachomatis , Neisseria gonorrhoea , Trachomonas vaginalis , Mycoplasma genitalium and herpes simplex virus 1/2 (HSV1/2) prevalence and associated factors among AGYW of Eastern Cape province, South Africa.

To the best of our knowledge, this is the first study to concurrently report on the prevalence of six different STIs and bacterial vaginosis among AGYW in the Eastern Cape Province of South Africa. The burden of bacterial vaginosis among South African Eastern Cape Province AGYW was similar to that reported among sub-Saharan African women (42.1%) [ 7 ] and South African AGYW (42–47.0%) [ 8 , 24 , 25 ]. In addition, it was slightly lower than the recent BV report (58.2%) among South African women with vaginal discharge syndrome and/or genital ulcer syndrome. Even though the majority of the current study population was not presenting with symptoms related to the above-mentioned syndromes. The high burden of STIs (HPV, C. trachomatis , N. gonorrhoeae , T. vaginalis , M. genitalium or HSV1/2) and its coinfection among Eastern Cape Province AGYW observed in this study is similar to that previously reported among the Western Cape and Gauteng provinces of South Africa, even though in the Eastern Cape AGYW, the STI prevalence was slightly elevated by between one and ten percentage [ 26 ]. The Western Cape and Gauteng Province AGYW were confirmed HIV-negative, while among those tested in the Eastern Cape study, 4.8% were HIV-positive. In addition, in the current study population, 31.1% had unknown HIV status. The high rate of BV, STIs and their coinfection in non HIV positive populations is of great concern and puts this group at an increased risk of other STIs, including lifelong STIs like HIV infection [ 27 , 28 ]. In addition, being previously or currently infected with an STI has been reported to increase the chances of future STI incidences [ 29 ]. Asymptomatic STIs also increase the risk of other STI acquisition, and asymptomatic STIs are common [ 7 , 11 , 30 ]. In STI control, identifying those at risk is important; therefore, the high rate of asymptomatic STIs affects infection control [ 31 ]. As previously mentioned, STIs can lead to infertility, several pregnancy complications and cancer [ 11 , 32 ]. It is unfortunate to observe a high burden of STI coinfection among AGYW, as it tends to lead to more severe clinical manifestations, and the presence of BV further complicates the dynamics [ 13 , 33 , 34 ]. Lactobacillus species in vaginal microbiome have been reported to lower the prevalence of STIs [ 3 , 4 , 6 ], similarly in this study, BV-negative AGYW had a lower prevalence of having multiple STIs than BV-positive AGYW, and having a high amount of Lactobacillus species among BV-negatives further decreased this prevalence. It was also interesting to note the importance of vaginal L actobacillus species amount on multiple STIs infection as demonstrated by decreased prevalence of multiple STIs among the BV-negative with a high amount of Lactobacillus species than those with a low amount of Lactobacillus species. Unfortunately, the current study detected three different Lactobacillus species ( L. crispatus , L. gasseri or L. jensenii ) combined, it would enhance the findings if the Lactobacillus species were separated as it is known that they offer different protection levels, for example Lactobacillus crispatus is reported to be the most protective [ 6 ]. The prevalence of Gardnerella vaginalis was high in both BV-positive and BV-negative women. However, its prevalence was similar between BV-positive and BV-negative, with a low amount of Lactobacillus species. This observation further emphasizes the domination of Gardnerella vaginalis when the Lactobacillus species get depleted in the vaginal microbiome [ 35 ]. Increased number of lifetime and current sexual partners are known risk factors of bacterial vaginosis [ 24 ]. and this has been noted in this study. Age-disparate relationships are common in South Africa and contribute to the high burden of diseases in AGYW [ 36 , 37 ]. In addition, current or previous (up to seven days) vaginal discharge was associated with BV. A recent microbiological sentinel surveillance in South Africa reported that half of the women with vaginal discharge syndrome had bacterial vaginosis [ 38 ]. The use of molecular based methods strengthened the study as it increases the sensitivity. It is acknowledged that using an additional commonly used BV diagnostic criteria such as Nugent scoring could have benefited the study. The Allplex™ Bacterial Vaginosis plus Assay detect the L. crispatus , L. gasseri and L. jensenii as a group. This limited further analysis of checking which one of the Lactobacillus was associated with the observed protection. This is important as Lactobacillus crispatus is reported to be the most protective Lactobacilli , and has been reported to be less dominant in vaginal microbiota of African women [ 6 ], is therefore, recommended that future studies investigate the Lactobacilli not as a group. Pregnancy and menstruation sometimes have an impact on vaginal microbiome due to this the study participant recruitment criteria included sexually experienced AGYW who were not menstruating or pregnant, on the day of enrolment.In addition, data on the menstrual cycle phase were not collected. These could act as a limitation of the study and limit generalizability. The secondary data used were generated from self-collected specimens; therefore, the inconsistent sampling between participants is possible, as the specimen collection instructions indicated that AGYW must insert the brush into the vagina as far as possible after assuming a comfortable position, and the inter-individual differences in anatomical site sampled are possible. Considering the impact of douching on the vaginal microbiome [ 39 ], it is unfortunate that this aspect was not investigated in this current study. Some of the investigated aspects relied on self-reported responses, which could act as a limitation in this study. The study population does not represent the whole Eastern Cape Province population and therefore, cannot be generalised. Even so, the data from this study remains important for Eastern Cape province and South Africa; more specifically, this is the first report to concurrently report on bacterial vaginosis and six different STIs among AGYW.

The bacterial vaginosis increased the risk of STIs and coinfection among AGYW. The presence and high amount of Lactobacillus species were associated with decreased risk of STIs. These findings indicate the urgent need to improve or strengthen bacterial vaginosis and STI prevention, detection and management among AGYW. The AGYW are the key population affected by STIs, and the design and implementation of mutual STIs screening programmes and education that favours them could be beneficial in communities. Data generated from this study could be used in STI intervention programs and policy. To further understand the benefits of Lactobacillus species on STIs and BV, large sample sizes and longitudinal studies are recommended.