Parts of this chapter have been reproduced from Daniels et al.1 This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: https://creativecommons.org/licenses/by/4.0/. The text below includes minor additions and formatting changes to the original text.
This chapter reports the effects of rapid intrapartum GBS testing in reducing maternal and neonatal antibiotic usage primarily, and on other neonatal and process outcomes, compared with usual care, in which IAP is directed based on maternal risk factors alone.
Intrapartum antibiotics prophylaxis to prevent early-onset group B Streptococcus infection
There were no differences in the proportion of women who were administered IAP for GBS prophylaxis (RR 1.16, 95% CI 0.83 to 1.64). Overall, 41% (297/716) of women in the rapid test group were given IAP for GBS prophylaxis, compared with 36% (328/906) of women in the usual-care group. The estimates are provided in Table 12 after adjusting for cluster size, unit birth rate and IAP rates.
| IAP for GBS | Rapid test, n (%) | Usual care, n (%) | RDa (95% CI); p-value | RRb (95% CI); p-value |
|---|---|---|---|---|
| Yes | 297 (41) | 328 (36) | 0.05 (–0.07 to 0.18); 0.37 | 1.16 (0.83 to 1.64); 0.35 |
| No | 419 (59) | 578 (64) | ||
| Total | 716 | 906 | ||
| Missing | 6 | 0 |
A post hoc sensitivity analysis that adjusted for maternal risk factors did not show a difference between the two strategies (RR 0.96, 95% CI 0.80 to 1.16).
Maternal antibiotic administration for any indication
There were no differences between women in the rapid test units (n = 484, 67%) and women in the usual-care units (n = 602, 66%) in terms of receiving antibiotics for any indication, indications other than caesarean delivery and postpartum antibiotics to prevent or treat infection (Table 13).
| Intrapartum maternal antibiotic | Rapid test, n (%) | Usual care, n (%) | RDa (95% CI); p-value | RRb (95% CI); p-value |
|---|---|---|---|---|
| Intrapartum maternal antibiotic use for any indication | ||||
| Yes | 484 (67) | 602 (66) | –0.007 (–0.14 to 0.12); 0.91 | 0.99 (0.81 to 1.21); 0.92 |
| No | 234 (33) | 304 (34) | ||
| Total | 718 | 906 | ||
| Missing | 4 | 0 | ||
| Intrapartum maternal antibiotic use for any indication other than a caesarean | ||||
| Yes | 454 (63) | 559 (62) | 0.007 (–0.11 to 0.13); 0.90 | 1.01 (0.83 to 1.23); 0.89 |
| No | 263 (37) | 347 (38) | ||
| Total | 717 | 906 | ||
| Missing | 5 | 0 | ||
| Postpartum maternal antibiotic use for any indication | ||||
| Yes | 146 (20) | 203 (22) | –0.02 (–0.12 to 0.08); 0.71 | 0.92 (0.60 to 1.44); 0.71 |
| No | 567 (80) | 702 (78) | ||
| Total | 713 | 905 | ||
| Missing | 9 | 1 | ||
There was a significant increase in the proportion of women who received sufficient antibiotic exposure (i.e. IAP exposure > 4 hours before birth) in the rapid test group compared with those in the usual-care group (RD 0.16, 95% CI 0.06 to 0.27). There were no differences in the rates of women with IAP exposure > 2 hours between the two strategies (Table 14).
| IAP exposure | Rapid test, n (%) | Usual care, n (%) | RDa (95% CI); p-value | RRb (95% CI); p-value |
|---|---|---|---|---|
| > 2 hours before birth | ||||
| Yes | 376 (79) | 380 (72) | 0.11 (–0.24 to 0.45); 0.16 | 1.10 (0.98 to 1.24); 0.09c |
| No | 100 (21) | 149 (28) | ||
| Total | 476 | 529 | ||
| > 4 hours before birth | ||||
| Yes | 322 (68) | 288 (54) | 0.16 (0.06 to 0.27); 0.005 | 1.32 (1.12 to 1.55); 0.004 |
| No | 154 (32) | 241 (46) | ||
| Total | 476 | 529 | ||
| Missing exposure duration data | 8 | 73 | ||
| Did not receive IAP | 234 | 304 | ||
Neonatal antibiotics exposure
The rates of neonatal exposure to antibiotics were lowered by 29% (RR 0.71, 95% CI 0.54 to 0.95) in the rapid test group compared with the usual-care group (Table 15). This included all babies who started antibiotics within the first 7 days of life, regardless of maternal antibiotic exposure or indication for neonatal antibiotic prescription. The number of babies for whom suspected early-onset sepsis was the indication for antibiotics was lower in the rapid test units (25%) than in the usual-care units (39%) (RR 0.63, 95% CI 0.43 to 0.92; p = 0.02).
| Neonatal antibiotic use for prophylaxis or treatment | Rapid test, n (%) | Usual care, n (%) | RDa (95% CI); p-value | RRb (95% CI); p-value |
|---|---|---|---|---|
| Yes | 244 (33) | 412 (44) | –0.13 (–0.23 to –0.02); 0.02 | 0.71 (0.54 to 0.95); 0.02c |
| No | 493 (67) | 534 (56) | ||
| Missing information | 11 | 1 | ||
| Stillbirths | 1 | 4 | ||
| Total | 749 | 951 |
The predominant reason stated for administration of neonatal antibiotics was suspected early-onset infection, which was the stated reason in one-third of all babies (Table 16).
| Reason for i.v. antibiotic administration | Rapid test (N = 749), n (%) of all babiesa | Usual care (N = 951), n (%) of all babiesb | Overall (N = 1700), n (%) of all babies |
|---|---|---|---|
| Prophylaxis in newborn despite the mother receiving IAP at least 2 hours before birth | 61 (8) | 48 (5) | 109 (6) |
| Prophylaxis in newborn because the mother received IAP < 2 hours before birth | 21 (3) | 29 (3) | 50 (3) |
| Prophylaxis in newborn because the mother did not receive any IAP | 17 (2) | 15 (2) | 32 (2) |
| The baby had suspected early-onset neonatal sepsis | 187 (25) | 374 (39) | 561 (33) |
| Other reason | 43 (6)c | 75 (8)d | 118 (7) |
In most of the babies with suspected early-onset infection who were commenced on antibiotics, following further tests, such as microbiological culture of blood or cerebrospinal fluid, the decision was made not to administer the full course of antibiotics (Tables 17–19). There were 11 reports of GBS infection among 561 babies who received antibiotics, equivalent to a rate of 6.5 per 1000 live births. Of these 11 babies, all of their mothers (n = 11) had received IAP. Two babies died before discharge, both in the usual-care group, and one death was judged to be because of GBS (the other death was due to E. coli meningitis). Three of these 11 babies were in the rapid test group and the mothers of all three returned a positive rapid test result. All three of these babies returned an ear canal swab, but only one baby was positive for GBS. There were three perinatal deaths in the rapid test units and eight in the usual-care units, which included one and four stillbirths, respectively.
| Management route | Rapid test (N = 187), n (%) | Usual care (N = 374), n (%) | Overall (N = 561), n (%) |
|---|---|---|---|
| Infection subsequently ruled out, clinically well and antibiotic treatment discontinued | 138 (72) | 260 (73) | 398 (72) |
| Infection not microbiologically confirmed, but a full course of antibiotics given | 46 (24) | 80 (22) | 126 (23) |
| Infection caused by GBS | 3 (2) | 8 (2) | 11 (2) |
| Infection caused by another bacterium | 6 (3) | 10 (3) | 16 (3) |
| Risk factor | Rapid test group, n/N (%) | Usual-care group, n/N (%) | RDa (95% CI) | RRb (95% CI) | Interaction p-value |
|---|---|---|---|---|---|
| Maternal pyrexia (> 38 °C) in labour | |||||
| Yes | 24/65 (37) | 48/156 (31) | 0.02 (–0.16 to 0.20) | 1.09 (0.65 to 1.83) | 0.79 |
| No | 273/651 (42) | 280/750 (37) | 0.05 (–0.07 to 0.18) | 1.16 (0.82 to 1.64) | |
| Total | 716 | 906 | |||
| Previous baby with GBS disease | |||||
| Yes | 17/51 (34) | 23/53 (43) | –0.04 (–0.26 to 0.17) | 0.87 (0.48 to 1.59) | 0.26 |
| No | 280/665 (42) | 305/853 (36) | 0.06 (–0.07 to 0.19) | 1.19 (0.84 to 1.67) | |
| Total | 716 | 906 | |||
| GBS bacterium detected in current pregnancy | |||||
| Yes | 156/330 (47) | 130/331 (39) | 0.09 (–0.04 to 0.22) | 1.27 (0.89 to 1.81) | 0.18 |
| No | 141/386 (37) | 198/575 (34) | 0.03 (–0.10 to 0.15) | 1.06 (0.75 to 1.50) | |
| Total | 716 | 906 | |||
| Preterm labour | |||||
| Yes | 121/320 (38) | 152/432 (35) | 0.03 (–0.10 to 0.16) | 1.08 (0.76 to 1.55) | 0.33 |
| No | 176/396 (44) | 176/474 (37) | 0.08 (–0.05 to 0.21) | 1.23 (0.87 to 1.76) | |
| Total | 716 | 906 | |||
| IAP for GBS | Rapid test group, n (%) | Usual-care group, n (%) | RDa (95% CI) | RRb (95% CI) |
|---|---|---|---|---|
| Received | 294 (44) | 325 (42) | 0.02 (–0.13 to 0.17) | 1.07 (0.74 to 1.54) |
| Did not receive | 367 (56) | 442 (58) | ||
| Total | 661 | 767 | ||
| Missing data on IAP use | 4 | |||
| Missing data on reason for IAP | 2 |
Subgroup and sensitivity analyses
Performing subgroup analyses for each of the four risk factors indicated that there was no evidence of any interaction between the subgroup category and the comparison of the primary outcome, nor any significant difference between the strategy groups for any subgroup (see Table 17).
Serious adverse outcomes
There were no reports of maternal anaphylaxis because of antibiotic administration or any reports of inoculation injury.