ABSTRACT Objective: The objective of this investigation was to determine the usefulness of blood cultures in evaluating patients with chorioamnionitis who were treated in accordance with a specific antibiotic protocol. Methods: We reviewed the records of 539 patients with chorioamnionitis who delivered at our facility over a 3 year period (July 1, 1989-June 30, 199

Gregory J Locksmith

Patrick Duff

CiteSeerX

Infectious Diseases in Obstetrics and Gynecology 2:11 I-II4 (1994)
(C) 1994 Wiley-Liss, Inc.
Assessment of the Value of Routine Blood Cultures in
the Evaluation and Treatment of Patients With
Chorioamnionitis
Gregory J. Locksmith and Patrick Duff
Division of Maternal-Fetal Medicine, Department of Obstetrics and Gynecology, University of Florida,
Gainesville, FL
ABSTRACT
Objective: The objective of this investigation was to determine the usefulness of blood cultures in
evaluating patients with chorioamnionitis who were treated in accordance with a specific antibiotic
protocol.
Methods: We reviewed the records of 539 patients with chorioamnionitis who delivered at our
facility over a 3 year period (July 1, 1989-June 30, 1992). Patients had one set of aerobic and
anaerobic blood cultures at the time of their initial assessment. They were treated initially with
ampicillin or vancomycin plus gentamicin. Those who required cesarean delivery also received
clindamycin postoperatively. Patients who had a poor initial response to therapy were treated
empirically with selected antibiotics targeted against likely resistant organisms until the results of
bacteriologic cultures were available. Bacteremic patients had repeat blood cultures while on ther-
apy. We analyzed the medical records to determine the frequency with which blood culture results
led to meaningful changes in patient management. We also compared the duration of febrile morbid-
ity in bacteremic vs. nonbacteremic patients.
Results: Thirty-nine of 538 patients (7.2%, 95% confidence interval [CI] 5.2-9.2%) had positive
blood cultures. In only one patient did the result of the blood culture definitively alter therapy. This
patient had a fever ofunknown origin, and the finding of a positive blood culture ultimately led to the
diagnosis of chorioamnionitis. The mean duration of febrile morbidity was not significantly different
in bacteremic vs. nonbacteremic patients (2.03 vs. 1.74 days). None of the repeat blood cultures was
positive. The cost of blood cultures in the study population was $72,759.00.
Conclusions: The routine use ofblood cultures in the assessment ofpatients with chorioamnionitis
rarely provides information that justifies a change in clinical management when patients are treated
in accordance with the specific antibiotic protocol outlined in this investigation.
(C) 1994 WileyoLiss, Inc.
KEY WORDS
Bacteremia, intva-amniotic infection, cost effectiveness, outcome analysis, intrapartum infection
horioamnionitis is a common and serious com-
plication of labor and delivery, occurring in
5-10% of patients. 1,2 Complications associated with
chorioamnionitis include increased likelihood of ce-
sarean delivery, neonatal sepsis and pneumonia,
and persistent postpartum infection. 3-6
Maternal bacteremia occurs in 5-10% of pa-
tients with chorioamnionitis. Blood cultures are fre-
quently recommended to guide antibiotic therapy.
On initial consideration, maternal bacteremia would
seem to indicate a more severe infection, requiring
longer administration of antibiotics and perhaps
repeat blood cultures later in the course of the ill-
ness to ensure that serious sequelae of bacteremia do
Address correspondence/reprint requests to Dr. Patrick Duff, Department of Obstetrics and Gynecology, University of
Florida College of Medicine, P.O. Box 100294, Gainesville, FL 32610-0294.
Received May 10, 994
Clinical Study Accepted August I, 1994
BLOOD CULTURES IN CHORIOAMNIONITIS
not ensue. 7-11 However, the clinical utility of rou-
tine blood cultures in this clinical setting has never
been assessed systematically.
Our objective in this study was to determine the
usefulness of blood cultures in evaluating patients
with chorioamnionitis who were treated in accor-
dance with a well-defined antibiotic protocol. Spe-
cifically, we sought to determine how frequently
blood culture results led to meaningful changes in
patient management.
MATERIALS AND METHODS
Using a computerized database, we identified the
medical records of all patients with chorioamnioni-
tis delivered at Shands Hospital-University ofFlor-
ida from July 1, 1989, to June 30, 1992. During
this period, 538 patients had a confirmed clinical
diagnosis of chorioamnionitis and had at least one
set of aerobic and anaerobic blood cultures at the
time of their initial assessment. The clinical diag-
nosis of chorioamnionitis was based on a maternal
fever of at least 37.8C, maternal and fetal tachy-
cardia, and uterine tenderness in the absence of any
other localizing sign of infection.
Once the diagnosis was established, the patients
were treated initially with IV ampicillin (2 g q 6h)
and gentamicin (1.5 mg/kg q 8 h). Those with a
history of penicillin allergy received gentamicin
(1.5 mg/kg q 8 h) and clindamycin (900 mg q 8
h). In patients receiving ampicillin plus gentami-
cin who had a cesarean delivery, clindamycin (900
mg q 8 h) was added to the antibiotic regimen
immediately postoperatively. 5 Patients undergoing
cesarean delivery who became febrile just prior to
surgery were treated with clindamycin plus gen-
tamicin immediately after the infant’s umbilical
cord was clamped.
If a patient receiving ampicillin plus gentamicin
failed to defervesce within 48 h, clindamycin was
empirically added to the antibiotic regimen to en-
hance coverage of anaerobic organisms. If a patient
receiving clindamycin plus gentamicin failed to de-
fervesce within 48 h, ampicillin or vancomycin was
administered to provide coverage of enterococci.
Antibiotic therapy was continued until the patient
had been afebrile for at least 24 h. Patients with
bacteremia had repeat blood cultures at the time the
initial cultures were reported as positive and were
LOCKSMITH AND DUFF
then arbitrarily continued on parenteral antibiotics
until the second set of cultures was negative at 48 h
of incubation. This practice was based upon our
concern with the theoretical possibility of serious
sequelae such as breakthrough bacteremia, septic
shock, and abscess formation in patients who had
positive blood cultures. 7’8’
We analyzed the medical records to determine
the prevalence and microbiology of bacteremia and
the clinical outcome of bacteremic patients. Specif-
ically, #e examined alterations in the selection of
individual antibiotics, results of repeat blood cul-
tures after apparent clinical cure, and causes for
failure of antibiotic therapy. We also compared the
duration of febrile morbidity in bacteremic vs. non-
bacteremic patients. The nonbacteremic patients
were selected from the study population using com-
puter-generated random numbers.
We analyzed our data with the unpaired, two-
tailed t-test. P < 0.05 was considered statistically
significant.
RESULTS
Of the 538 patients studied, 39 (7.2%, 95% confi-
dence interval [CI] 5.2-9.2%) had positive blood
cultures at the time of diagnosis. In 13 additional
cass (2.4%, 95% CI 1.2-3.6%), coagulase-nega-
tive staphylococci or diphtheroid organisms were
cultured from the blood and were considered to be
skin contaminants. The most common pathogenic
organisms were group B streptococci (15), Escher-
ichia coli (9), anaerobic organisms (5), group A
streptococci (4), and group D streptococci (3).
Of the 39 bacteremic patients, 7 had a change in
their antibiotic coverage. In 4 cases, the change in
therapy was based on a lack of clinical response to
the initial therapy. Two of these patients had been
diagnosed with chorioamnionitis just prior to un-
dergoing cesarean delivery and were treated with
clindamycin plus gentamicin after clamping of the
infant’s umbilical cord. Ampicillin was empirically
added to the antibiotic regimen 24-36 h later be-
cause of persistent high fever. One patient subse-
quently had a blood culture positive for entero-
cocci, but the other patient’s blood culture grew
group B streptococci which was sensitive to clin-
damycin. Another patient was placed on ampicillin
plus gentamicin during labor and delivered vagi-
112 INFECTIOUS DISEASES IN OBSTETRICS AND GYNECOLOGY
BLOOD CULTURES IN CHORIOAMNIONITIS LOCKSMITH AND DUFF
nally. She continued to have a high fever 24 h
postpartum so clindamycin was empirically added
to the antibiotic regimen. Her blood culture was
subsequently positive for Peptostreptococcus species.
The final patient was discharged home afebrile af-
ter receiving ampicillin plus gentamicin for 24 h
postpartum. She was readmitted 24 h after dis-
charge with recurrent fever and empirically treated
with ampicillin plus clindamycin plus gentamicin.
Her aerobic blood culture was positive for gram-
negative rods, but exact identification of the organ-
ism was not possible. She subsequently defervesced
after 4 days of treatment.
In 3 cases, the change in therapy was based on
blood culture results. In one ofthese patients, ampi-
cillin was added to a clindamycin plus gentamicin
regimen when the blood culture was found to have
gram-positive cocci in pairs and chains. The organ-
ism was eventually identified as group B strepto-
cocci which was sensitive to the original antibiotic,
clindamycin. Therefore, in retrospect, the addition
of ampicillin was unnecessary. Another patient was
initially placed on ampicillin and gentamicin, and
Klebsiella pneumoniae was cultured from the blood.
The organism was sensitive to both ampicillin and
gentamicin, but the coverage was changed to ceftri-
axone because the patient developed a coexistent
pneumonia and an internal-medicine consultant rec-
ommended this change. Thus, in this instance, the
blood culture result was not the decisive factor in
altering antibiotic therapy. One patient presented
to labor and delivery at 39 weeks with intact mem-
branes, fever, and leukocytosis. The source of her
infection was initially unknown, so cultures were
taken from her blood, urine, and amniotic fluid.
Although all cultures were subsequently positive,
the blood culture was the first specimen to grow
group B streptococci, and the diagnosis of chorio-
amnionitis was based on this result. The patient was
then treated with antibiotics, and her delivery was
expedited. Among the bacteremic patients, 28 had
repeat blood cultures at the time the initial cultures
were reported as positive. All repeat blood cultures
were negative. In no instance, then, did the repeat
cultures alter therapy.
The mean duration of fever in the bacteremic
patients was 2.03 days, and the median was day.
For the nonbacteremic patients, the mean and me-
dian durations of febrile illness were 1.74 days and
day, respectively. These observed differences
were not statistically significant. The inpatient cost
for a set of aerobic and anaerobic blood cultures at
our center is $118.50. Thus, the total cost of blood
cultures in our study population was $72,759.00.
DISCUSSION
The rationale for routinely obtaining blood cultures
in patients with chorioamnionitis is to guide the
selection of antibiotics and to identify more seri-
ously ill patients who may require longer ther-
apy. 7-11 Because of the polymicrobial nature of
chorioamnionitis, many different pathogens may
be isolated from bacteremic patients. 12 In our study,
we recovered 12 different organisms in 39 positive
blood cultures.
At our center, patients with chorioamnionitis are
typically placed on of 3 antibiotic regimens: ampi-
cillin plus gentamicin, clindamycin plus gentami-
cin, or ampicillin plus clindamycin plus gentami-
cin. Any of these combinations should adequately
treat infection caused by group A or B streptococci,
anaerobic streptococci, E. coli, and most strains of
staphylococci. A possible cause for concern is the
patient with an enterococcal bacteremia being
treated with gentamicin and clindamycin or the
patieht with an anaerobic gram-negative bacillus in
the blood who is receiving ampicillin and gentami-
cin. Gram-negative aerobic bacilli that are resistant
to aminoglycosides are unlikely to be encountered
except in immunocompromised patients.
In only one case did the initial blood culture
results definitively change therapy, and this in-
stance was a patient with a fever of undetermined
origin. The blood culture result was instrumental
in establishing the diagnosis of chorioamnionitis
in that case. There were 3 instances in which pa-
tients with enterococcal or anaerobic bacteremia
were inadequately treated with the initial antibiotic
therapy. In each of these cases, a lack of clinical
response to therapy was noted before the blood
culture results became available, and the antibiotic
coverage was appropriately broadened. The 2
isolates of Staphylococcus aureus were sensitive to
both gentamicin and clindamycin; in each case, the
patients defervesced within 2 days of starting ther-
apy.
None of the repeat blood cultures was positive.
INFECTIOUS DISEASES IN OBSTETRICS AND GYNECOLOGY
BLOOD CULTURES IN CHORIOAMNIONITIS LOCKSMITH AND DUFF
Thus, in view of the comparable duration of febrile
morbidity in bacteremic vs. nonbacteremic patients,
the extended duration of antibiotic therapy in the
former may not have been necessary. MacMillan
and Grimes 13 have similarly demonstrated the lim-
ited usefulness of blood and urine cultures in treat-
ing pregnant patients with pyelonephritis.
Therefore, based on our findings, we conclude
that the routine use of blood cultures does not im-
prove diagnostic certainty in evaluating patients
with chorioamnionitis who are treated in accor-
dance with the antibiotic protocol used in this in-
vestigation. We acknowledge that none of the
bacteremic patients in our study were immuno-
suppressed and none had underlying cardiac disease
predisposing them to endocarditis. Blood cultures
certainly are indicated in patients with heart disease
who are at risk for endocarditis, in IV-drug abus-
ers, in patients who have prosthetic heart valves or
grafts, and in patients who are immunocompro-
raised or who have an uncertain diagnosis. Addi-
tionally, blood cultures may be useful in evaluating
patients who have a poor response to the initial
antibiotic therapy or who may be at risk for having
a highly resistant microorganism because of pro-
longed hospitalization or antibiotic therapy. How-
ever, one of these conditions is likely to be present
in no more than 10% of patients. By using blood
cultures more selectively in evaluating women with
chorioamnionitis, obstetricians can simplify plans
of management and lower treatment costs without
compromising patient care.
REFERENCES
1. Newton ER, Prihoda TJ, Gibbs RS: Logistic regression
analysis of risk factors for intra-amniotic infection. Ob-
stet Gynecol 73:571-575, 1989.
2. Soper DE, Mayhall CG, Dalton HP: Risk factors for
intraamniotic infection: A prospective epidemiologic
study. Am J Obstet Gynecol 161:562-568, 1989.
3. Sperling RS, Ramamurthy RS, Gibbs RS: A comparison of
intrapartum versus immediate postpartum treatment of in-
tra-amniotic infection. Obstet Gyneco170:861-865, 1987.
4. Sperling RS, Newton E, Gibbs RS: Intra-amniotic infec-
tion in low-birthweight infants. J Infect Dis 157:113-
117, 1988.
5. Gibbs RS, Duff P: Progress in pathogenesis and manage-
ment of clinical intraamniotic infection. Am J Obstet
Gynecol 164:1317-1326, 1991.
6. Duff P: Pathophysiology and management of postcesar-
ean endomyometritis. Obstet Gyneco167:269-276, 1986.
7. Duff P, Gibbs RS: Maternal sepsis. In Berkowitz RL
(ed): Critical Care of the Obstetric Patient. New York:
Churchill Livingstone, pp 189-217, 1983.
8. DiZerega GS, Yonekura ML, Keegan K, Roy S, Naka-
mura R, Ledger W: Bacteremia in post-cesarean section
endomyometritis: Differential response to therapy. Ob-
stet Gynecol 55:587-590, 1980.
9. Blanco JD, Gibbs RS, Castaneda YS: Bacteremia in obstet-
rics: Clinical course. Obstet Gynecol 58:621-625, 1981.
10. Ledger WJ, Norman M, Gee C, Lewis W: Bacteremia
on an obstetric-gynecologic service. Am J Obstet Gynecol
121:205-212, 1975.
11. Kreger BE, Craven DE, Carling PC, McCabe WR: Gram-
negative bacteremia. Am J Med 68:332-343, 1980.
12. Monif GRG, Baer I-I: Polymicrobial bacteremia in ob-
stetric patients. Obstet Gynecol 48:167-169, 1976.
13. MacMillan MC, Grimes DA: The limited usefulness of
urine and blood cultures in treating pyelonephritis in
pregnancy. Obstet Gynecol 78:745-748, 1991.
114 INFECTIOUS DISEASES IN OBSTETRICS AND GYNECOLOGY
Submit your manuscripts at
http://www.hindawi.com
Stem Cells
International
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
MEDIATORS
INFLAMMATION
of
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Behavioural 
Neurology
Endocrinology
International Journal of
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Disease Markers
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
BioMed 
Research International
Oncology
Journal of
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Oxidative Medicine and 
Cellular Longevity
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
PPAR Research
The Scientific 
World Journal
Hindawi Publishing Corporation 
http://www.hindawi.com Volume 2014
Immunology Research
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Journal of
Obesity
Journal of
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
 Computational and  
Mathematical Methods 
in Medicine
Ophthalmology
Journal of
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Diabetes Research
Journal of
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Research and Treatment
AIDS
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Gastroenterology 
Research and Practice
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Parkinson’s 
Disease
Evidence-Based 
Complementary and 
Alternative Medicine
Volume 2014
Hindawi Publishing Corporation
http://www.hindawi.com


Assessment of the Value of Routine Blood Cultures in the Evaluation and Treatment of Patients With Chorioamnionitis

http://citeseerx.ist.psu.edu/viewdoc/download;jsessionid=6D1D4A67F2304C9762743DA556C7B359?doi=10.1.1.1042.2910&rep=rep1&type=pdf

Assessment of the Value of Routine Blood Cultures in the Evaluation and Treatment of Patients With Chorioamnionitis

Abstract

Similar works

Full text

Available Versions

CiteSeerX