Steady-state cord and amniotic fluid ceftizoxime levels continuously surpass maternal levels

Antibiotic therapy for preterm premature rupture of the membranes

Amniotic fluid studies and placental histopathological evaluation have confirmed the association between intrauterine infection and preterm premature rupture of the membranes (pPROM). This association is increasingly strong with pPROM at early gestational ages. The organisms associated with pPROM include a broad spectrum of aerobic and anaerobic gram-positive and gram-negative bacteria. In many cases, the patient presenting with pPROM will have overt intrauterine infection necessitating delivery. For those amenable to expectant management, the clinical course is usually of brief latency between membrane rupture and delivery. A number of well-designed prospective clinical trials have evaluated the utility of antibiotic treatment during the expectant management of pPROM. Taken together, these studies suggest broad spectrum antibiotic treatment of this population to enhance pregnancy prolongation, and to reduce maternal and neonatal infectious morbidity. There are some data suggesting the potential for a reduction in neonatal gestational age-dependent morbidity. We recommend aggressive adjunctive antibiotic treatment to prolong pregnancy and reduce morbidity in patients with pPROM, at gestations remote from term, when a significant improvement in neonatal outcome can anticipated with expectant management.

Antimicrobial therapy in expectant management of preterm premature rupture of the membranes

We review the impact of antimicrobial treatment on maternal and fetal outcome during expectant management of preterm premature rupture of the membranes. Relevant studies were retrieved from Medline (1966 to August, 1994) with the search term fetal-membrane-premature-rupture and antibiotics or antimicrobial, Excerpta Medica (1972 to August, 1994) with the search term premature fetus, membrane rupture, and antibiotic or antimicrobial therapy, and the Cochrane database of systemic reviews with the criterion antibiotics and prelabour rupture of membranes. We also obtained unpublished data from a randomised clinical trial of ceftizoxime versus placebo. The selected studies were randomised controlled trials of systemic antimicrobial therapy for prolongation of gestation in non-labouring women after preterm premature rupture of the membranes. Data extraction was done by a single reviewer. Studies were evaluated for post-randomisation exclusion and other confounding variables that might introduce analytical bias. Analysis was done with SAS statistical software by a blinded investigator. Antimicrobial therapy after preterm premature rupture of the membranes is associated with a reduced number of women delivering within 1 week (62 vs 76%; OR 0.51, 95% CI 0.41-0.68), and reduced diagnosis of maternal morbidity including chorioamnionitis (12 vs 23%; 0.45, 0.33-0.60) and postpartum infection (8 vs 12%; 0.63, 0.41-0.97). Fetal morbidity, including confirmed sepsis (5 vs 9%; 0.57, 0.36-0.88), pneumonia (1 vs 3%; 0.32, 0.11-0.96), and intraventricular haemorrhage (9 vs 14%; 0.65, 0.45-0.92) were less often diagnosed after antimicrobial therapy. Separate analysis of the six placebo-controlled trials revealed similar or improved odds of pregnancy prolongation, chorioamnionitis, neonatal sepsis, postpartum infection, positive infant blood cultures, and pneumonia. Antimicrobial therapy, when used in the expectant management of preterm premature rupture of the membranes is associated with prolongation of pregnancy and a reduction in the diagnosis of maternal and infant morbidity. Further study should be directed towards determination of optimal antimicrobial therapy, increasing pregnancy prolongation, and enhancement of corticosteroid therapy for induction of pulmonary maturity after preterm premature rupture of the membranes.

A randomized, prospective study of adjunctive ceftizoxime in preterm labor

OBJECTIVE

Our purpose was to determine the effect of ceftizoxime in the prolongation of pregnancies receiving tocolysis for preterm labor.

STUDY DESIGN

A prospective, randomized, double-blinded, placebo-controlled trial was conducted in patients with preterm labor between 24 and 35 weeks' gestation. A total of 545 patients with intact membranes and without chorioamnionitis who were receiving magnesium sulfate were screened. Exclusions were for advanced cervical dilatation, penicillin allergy, current antibiotic therapy, and failure to give informed consent. Of these, 117 consecutive, eligible, consenting patients were randomized to receive either 2 gm of ceftizoxime or a placebo every 8 hours. The primary end point was prolongation of gestation. Statistical comparisons were performed by use of unpaired two-tailed t tests and chi 2 analysis.

RESULTS

Of the 58 ceftizoxime and 59 placebo patients, there was no difference in the interval to delivery (34.5 +/- 21.1 days vs 34.6 +/- 24.5 days, p = 0.99) and no difference in the rate of delivery before 37 weeks' gestation (60% in the ceftizoxime group vs 58% in the placebo group, p = 0.91). Subanalyses of 61 subjects who received nine or more doses and who were group B streptococci negative, 69 patients at < or = 32 weeks on presentation, and 22 sets of twins all showed no differences in delivery interval or rate of delivery at < 37 weeks. The sample size of this study was sufficient to detect a 9-day difference in prolongation of pregnancy (alpha = 0.05, beta = 0.2).

CONCLUSIONS

Ceftizoxime had no effect on interval to delivery or duration of pregnancy in women treated for preterm labor.

Differential protein binding of ceftizoxime in cord versus maternal serum

Ceftizoxime concentrations are higher in cord blood and amniotic fluid than in maternal blood. More avid binding to fetal serum proteins is a suggested mechanism. We measured ceftizoxime protein binding in fetal and maternal blood and documented significantly less protein binding to fetal proteins (21.9% vs 57.8%).

Transplacental transfer of cefuroxime in uncomplicated pregnancies and those complicated by hydrops or changes in amniotic fluid volume

The transplacental transfer of cefuroxime was determined at antenatal fetal blood sampling in a cross sectional study of 78 patients between 15-35 weeks' gestation, 8-138 minutes after a maternal intravenous dose of 750 mg. Mean serum cefuroxime concentration, measured by high performance liquid chromatography, was 7.4 (95% confidence interval (CI) 6.8 to 8.1) mg/l in control fetuses; concentrations in hydropic fetuses were similar (6.2 mg/l, CI 4.7 to 7.7) but in fetuses with oligohydramnios they were significantly lower, (4.9 mg/l, CI 3.6 to 6.2). Antibiotic concentration did not correlate with gestational age and remained unchanged by transfusion of packed red cells. We conclude that (i) fetal serum concentrations of cefuroxime obtained after a maternal dose of 750 mg are only adequate for prophylaxis against organisms with a minimum inhibitory concentration of < 4 mg/l and (ii) transplacental passage of cefuroxime is significantly reduced in the presence of oligohydramnios.

Transfer of Timentin (ticarcillin and clavulanic acid) across the in vitro perfused human placenta: comparison with other agents

OBJECTIVES

In vitro perfusion of human placentas was used to quantify the net placental transfer of ticarcillin and clavulanic acid.

STUDY DESIGN

Placentas were obtained from uncomplicated pregnancies at term. The maternal and fetal circulations were reestablished at flow rates of 17.5 ml/min and 5 ml/min, respectively. Open circulations were used to evaluate steady-state pharmacodynamics and transplacental gradient formation. Drug levels were measured by high-pressure liquid chromatography.

RESULTS

The clearance index of ticarcillin was 0.037 +/- 0.004. The fetal/maternal ratio was 0.91. Therapeutic concentrations of clavulanate (2 to 6 micrograms/ml) in the maternal media resulted in undetectable transfer to the fetal compartment. By using higher levels of clavulanate, a clearance index of 0.061 +/- 0.001 (mean +/- SEM) and 1:1 fetal/maternal gradient was obtained.

CONCLUSIONS

These data correspond to relatively low transfer of ticarcillin with a cord/maternal ratio of < 1. Clavulanate transfer is slightly greater. Agents with similar activity and superior transfer would optimize intrauterine treatment.

Serum and blister fluid pharmacokinetics and bactericidal activities of ampicillin-sulbactam, cefotetan, cefoxitin, ceftizoxime, and ticarcillin-clavulanate

Ampicillin-sulbactam, ticarcillin-clavulanate, cefoxitin, cefotetan, and ceftizoxime are promoted for the treatment of mixed aerobic-anaerobic bacterial infections. Their activities have been compared in vitro but not in vivo. In order to assess the in vivo activities of these agents in serum and interstitial fluid, we administered single, intravenous doses of these antimicrobial agents to healthy subjects. Concentrations of the antimicrobial agents in serum and suction-induced blister fluid and bactericidal activity were measured by high-pressure liquid chromatography and the standard methodology of the National Committee for Clinical Laboratory Standards, respectively. The organisms used for bactericidal activity tests were one isolate each of Staphylococcus aureus, Klebsiella pneumoniae, and Bacteroides fragilis. Pharmacokinetic parameters in serum and blister fluid were similar to those derived in other investigations. Of note were the high and prolonged concentrations of ticarcillin and cefotetan in blister fluid, despite high-level serum protein binding. The bactericidal activities in serum and blister fluid reflected the relative in vitro activities and kinetic dispositions of the various antimicrobial agents except for the bactericidal activity of cefotetan, which was substantially lower in blister fluid than serum, despite a blister fluid:serum area under the concentration-time curve ratio of 1.5. Similarly, the activity of ticarcillin-clavulanate in blister fluid was also substantially less than would have been predicted by the blister fluid:serum ratio of the area under the concentration-time curve of 1.1, possibly because of the low concentrations of clavulanate in blister fluid. The rankings of the in vivo bactericidal activities of the five drugs were as follows: for S. aureus, ampicillin-sulbactam > ticarcillin-clavulanate > ceftizoxime > cefoxitin > cefotetan; for K. pneumoniae, ceftizoxime > cefotetan > ampicillin-sulbactam = ticarcillin-clavulanate > cefoxitin; and for B.fragilis, ticarcillin-clavulanate > cefotetan > ceftizoxime > ampicillin-sulbactam = cefoxitin.