"GBS identified in clean-catch urine specimens during any trimester is considered a surrogate for heavy maternal colonization and also is associated with a higher risk for early-onset GBS disease"
from the Current CDC recommendations also-
"Although some women receive antibiotics to treat GBS bacteriuria during pregnancy, antibiotics do not eliminate GBS from the genitourinary and gastrointestinal tracts, and recolonization after a course of antibiotics is typical (71,131,132). Studies have found that some women with GBS bacteriuria during the first trimester might not have vaginal-rectal colonization detected at 35--37 weeks' gestation (130) or at the time of delivery (133). However, maternal GBS bacteriuria at any point during pregnancy is a recognized risk factor for early-onset GBS disease and therefore has been included as an indication for intrapartum antibiotic prophylaxis since 1996.
Subsequent observational studies have found the effectiveness to be 86%--89% among infants born to women who received intrapartum GBS prophylaxis
In reading over the higher dose 4.8m IM penicillin the studies were small but promising with no heavily colonized patients ... Highest levels of antibiotics if within 4 weeks of shot,
i know that the CDC guidelines was recognizing there is something up with other flora but nothing solidly proven other than greater incidence of resistant ecoli strains...
There are 2 very recently published studies that point to other flora taking the lead in infections.
J Perinatol. 2011 Apr 28.
Early-onset neonatal sepsis: rate and organism pattern between 2003 and 2008.
Sgro M, Shah PS, Campbell D, Tenuta A, Shivananda S, Lee SK.
Skipping intro and basic birth population numbers
"Result:A total of 405 infants had positive blood and/or cerebral spinal fluid cultures over the study period. The EONS rate was 6.8/1000 admissions (n=24969) in the earlier cohort compared with 6.2/1000 admissions (n=37484) in the later cohort (P=0.36). Rate of clinical chorioamnionitis was higher in the later cohort (38 vs 26%; P=0.02). For term infants, coagulase-negative Staphylococcus (CONS) (2.4/1000) followed by group B Streptococcus (GBS) (1.9/1000) were the most common organisms identified. For preterm infants, CONS (2.5/1000) followed by Escherichia coli (2.6/1000) were the most common organisms identified. There was a significant reduction in GBS EONS over time (P<0.01) and a trend toward an increase in other organisms.Conclusion:Although the rate of EONS among neonates admitted to NICUs has not changed, the pattern of infection has changed over the past 6 years. With the increased use of prophylactic antibiotics to mothers, careful surveillance of the changing trend of bacterial organisms among neonates is warranted.
.Journal of Perinatology advance online publication, 28 April 2011; doi:10.1038/jp.2011.40."
Pediatr Neonatol. 2011 Apr;52(2):78-84. Epub 2011 Mar 16.
The Changing Face of Early-onset Neonatal Sepsis After the Implementation of a Maternal Group B Streptococcus Screening and Intrapartum Prophylaxis Policy-A Study in One Medical Center.
Lin CY, Hsu CH, Huang FY, Chang JH, Hung HY, Kao HA, Peng CC, Jim WT, Chi H, Chiu NC, Chang TY, Chen CY, Chen CP.
Division of Neonatology, Department of Pediatrics, Mackay Memorial Hospital, Taipei, Taiwan.
"The GBS screening rate increased from 10.11% in 2004 to 65% in 2008 and the IAP rate increased from 40% in 2004 to 90% in 2008. The most common EOS pathogen in Period 1 was GBS (45.4%), which decreased to 20% in Period 2 (p=0.081; trend p=0.009). The percentage of EOS because of Escherichia coli in Period 1 was 40.9% but increased to 70% in Period 2 (p=0.059). E coli EOS increased in extremely low birth weight premature babies weighing 500-1000g from Period 1 to Period 2 (p=0.031). The incidence of ampicillin-resistant E coli EOS was relatively high, but no significant change (88.9% vs. 92.9%) after implementation of GBS screening and IAP was noted."