Premature rupture of membranes and effects of prophylactic antibiotics

Cow's milk and the emergence of group B streptococcal disease in newborn babies

BACKGROUND

Group B streptococcus (GBS), the most significant cause of neonatal bacterial sepsis, is thought to have emerged in the 1960s. GBS also causes mastitis in cows, and there is indirect evidence that human GBS is derived from a bovine ancestor.

OBJECTIVE

A major change in the collection of milk from farms, using bulk tanks rather than churns, occurred in the 1960s. We sought to define the temporal relationship between this change in farming and the emergence of GBS neonatal disease.

METHODS

We searched PubMed for reports of GBS disease from 1930 until 1980 to more exactly determine the time of emergence of neonatal infection and supported this data with UK hospital admission statistics for GBS infections. We identified the dates of the change from churns to bulk tanks by searching the internet and books for information on the history of milk transportation, farming and milk collection in the UK.

RESULTS

There are no PubMed reports of neonatal GBS disease between 1930 and 1950, and reports from the UK only emerged in the mid-1960s, confirming the notion that GBS neonatal infection was a newly emergent disease in the 1960s. No national data on hospital admissions are available around this time, but the Oxford Record Linkage Study, with admission data available for Oxford from 1968, showed no cases of neonatal disease until 1974. Cow's milk collection in the UK switched to bulk tank between 1960 and 1979, and publications relating to GBS disease emerged soon after.

CONCLUSIONS

There is a temporal relationship between the emergence of neonatal GBS disease reports in the UK in the 1960s and a change in cow's milk collection. This finding may be a temporal coincidence or may add support to the notion that human GBS was historically derived from a bovine ancestor.

[Risk factors associated with nosocomial bacteremia in low birth weight neonates. Grady Memorial Hospital, Atlanta]

BACKGROUND

Nosocomial bloodstream infections occur frequently in Neonatal Intensive Care Units and are associated with recognized and unrecognized risk factors. Little has been published regarding risk factors for bloodstream infections in low birth weight neonates.

OBJECTIVE

To investigate risk factors for bloodstream infection in neonates < 1,500 g admitted at a Neonatal Intensive Care Unit.

METHODS

A prospective study was undertaken in low birth weight neonates (< 1,500g) during a 22 months period. Bivariant, and logistic regresion (stepwise procedure) analysis was used to determine the significance association of bloodstream infection and perinatal and nosocomial risk factors.

RESULTS

A total of 72 patiens with nosocomial bacteriemia and 147 non bacteriemic patients were studied. Independent risk factors associated with bloodstream infection were birth weight, persistence of umbilical catheter > 7 days and persistence of peripheral arterial catheter > 1 day.

CONCLUSIONS

The uses of umbilical catheter > 7 days, peripheral arterial catheter > 1 day and birth weight < 1,500 g were significant determinants of nosocomial bloodstream infection risk. Because of the importance of invasive procedures as a source of nosocomial bloodstream infections, the lines duration needs to be reviewed with the aim of reducing the incidence of blood stream infection.

Perinatal risk factors in neonatal infections

Perinatal risk factors were studied among 50 cases of neonatal septicemia and 200 matched normal neonates during one year period. The consanguinity among parents, birth order and sex of the baby did not increase the risk for developing septicemia. There was significant increase in the risk for septicemia when the duration of labour was more than 24 hours (P less than 0.01), time interval between rupture of membrane and delivery of baby was more than 12 hours (P less than 0.001), liquor was meconium stained or foul smelling (P less than 0.001) and delivery was operative (P less than 0.01). The neonatal factors identified with risk for septicemia were preterm delivery (P less than 0.01), low birth weight (P less than 0.01), birth asphyxia (P less than 0.001) assisted ventilation (P less than 0.001) and intravenous alimentation (P less than 0.02). Identification of high risk pregnancies and appropriate management can minimize many of the above risk factors which in turn will reduce the occurrence of neonatal sepsis.

Neonatal sepsis resulting from possible amniotic fluid infection: risk and detection

Antibiotics are frequently prescribed "prophylactically" when the neonate is considered to be at risk for infection. The risk factors of prolonged rupture of membranes (greater than 24 hours), maternal fever/infection, and/or unexplained preterm labor (suggesting possible anmiotic fluid infection) were investigated in 276 babies. Only two of 150 babies investigated for a single factor proved to have sepsis, while of the 126 babies who had multiple factors, 13 had sepsis. Several laboratory tests, used singly or in combination, were more helpful than clinical manifestations in predicting which babies were likely to be infected. Neonatal sepsis was present in 6 per cent of the total, in 10 per cent of neonates with clinical signs, in 21 per cent with an increased immature/total neutrophil ratio (I/T ratio greater than or equal to 0.2), and in 36 per cent of infants with a positive "sepsis screen." The incidence of "infection" (sepsis and "very probable" infection) was 12 per cent overall, but was 14 per cent with neonatal signs, 44 per cent with I/T ratio greater than or equal to 0.2, and 74 per cent in those with a positive sepsis screen. A leukocyte count less than 5,000/cu mm and/or an I/T ratio greater than or equal to 0.2 was 100 per cent sensitive for sepsis, but the sepsis screen was most "efficient" at detecting "infection." Starting antibiotics on the basis of risk factors alone does not seem appropriate. In situations where amniotic fluid infection is possible, evaluation with the leukocyte count and differential (with or without other tests) could decrease the indiscriminate use of antibiotics, particularly when a single risk factor is the reason for suspecting infection.

Umbilical artery catheterization in newborns. II. Infections in relation to catheterization

Infections, as a complication of umbilical artery catheterization, were studied in 65 sick newborn infants. Every second day during the catheterization period peripheral blood cultures as well as blood samples for white cell count and platelets were taken. Cultures were taken from the catheter tips and from the umbilicus at the time of withdrawal of the catheter. Local or systemic antibiotics were not used prophylactically, but on rather broad clinical indications. No case of septicemia was found, but 8 infants had positive blood cultures and 16 had positive catheter tip cultures. Positive catheter tip culture occurred more often in infants who were born before 32 weeks of gestational age. Neither the duration of the catheterization nor the treatment with antibiotics influenced significantly the frequency of positive cultures.

Significance of raised immunoglobulin M levels in cord blood of small-for-gestational-age infants

Cord IgM values were determined in small-for-gestational-age infants born at Hammersmith Hospital during a 5 1/2-year period. 121 (12.5%) infants had levels more than 0.2 g/l; in 92 these were between 0.21 and 0.3 g/l. In only 18 (14.8%) was a level of 0.4 g/l exceeded, and 5 proved cases of intrauterine infection--rubella (2), syphilis (2), and toxoplasmosis (1)--were in this group. The factor most often associated with cord IgM more than 0.4 g/l was prolonged rupture of the membranes. There was an increased incidence of blood group B among the mothers, probably reflecting the greater number of nonCaucasian women giving birth to small-for-gestational-age infants. Determination of cord IgM did not help significantly indiagnosis.