Baylor

Neonatal septicemia is a low-incidence, high-risk disease with reported rates of 1-5 cases of sepsis for every 1000 livebirths. Many evaluations for infection are performed to detect a single case of serious infection. Since it is difficult to prospectively identify infants with infection, evaluations are performed when maternal risk factors are present (e.g. chorioamnionitis) or the infant manifests symptoms whereupon antibiotics are begun. Antibiotics are administered until the cultures are reported as negative. Length of antibiotic therapy has been traditionally recommended for 72 hours since this is the length of time reported to insure that all cultures will remain negative.Newer culture media and automated, computer-assisted blood culture systems have reduced the length of time required to determine positivity and therefore assure negativity. We have recently reported the use of one such blood culture system (ESP Blood Culture System, Trek Diagnostic Systems, Inc, Westlake, OH) in a large group of newborn infants (Pediatrics 2000;105:523-527). This system allowed for the reduction of antibiotic administration to between 24-36 hours in a population of newborns with suspected infection. This has had significant impact in these patients' management with both a reduction in antibiotic usage and a reduction in the length of hospitalization. The reduction in antibiotic usage also influences antibiotic pressure in our neonatal nurseries and potentially reduces the selection of multiple-drug resistant microorganisms. Before a general recommendation regarding length of treatment in newborn infants can be made, similar data should be obtained utilizing the more commonly used automated, computer-assisted blood culture systems (Bactec, BacTAlert). The ESP system measures the pressure in the head-space of each blood culture bottle to detect positivity. The change in pressure reflects the production or utilization of gas by the microorganisms. The Bactec system detects microorganisms by using ruthenium pentahydrate oxygen sensor embedded in silicon at the bottom of the blood culture vial. This material (ruthenium pentahydrate) flouresces following oxygen reduction induced by metabolizing microorganisms in the culture media. Data on this Bactec system has been collected (H-9837) and it is awaiting analysis. A third commonly used system is the BacTAlert blood culture system which also uses a colorimetric change in a special disk in the blood culture bottle which occurs with the production of carbon dioxide by microbes collected in the blood culture bottle. The BacTAlert system has recently replaced the ESP blood culture system at Ben Taub although it has been the customary system used at the Lyndon B. Johnson Nurseries since 1999 for blood culture processing.

(1) Evaluate the rapidity with which the BacTAlert Blood Culture System and BacTAlert culture media can detect microorganisms in positive blood cultures in a population of newborn infants from data collected beginning in 2000 at Lyndon B. Johnson Hospital and beginning in September 2003 at Ben Taub General Hospital. (2) Evaluate whether positive blood cultures obtained after antibiotic treatment has been initiated will grow just as rapidly using the BacTAlert System as those obtained prior to initiating antimicrobial therapy. (3) Complete data collection of the ESP blood culture system data at Ben Taub Nursery Service from May 2003 through September of 2003. (4) Compare the results using the BacTAert system with those obtained by the ESP system and the Bactec system (H9837).

Specimen/laboratory experiment

There are no risks or discomforts associated with this study except for the possible risk of loss of confidentiality. All steps required to maintain confidentiality of the patients would be maintained and identifiers will not be utilized in any papers generated by this data.

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