Daily Blood Cultures Research Articles

Predictors of acquiring a nosocomial bloodstream infection on extracorporeal membrane oxygenation

Purpose: The aim of this study was to identify independent predictors of acquiring a nosocomial bloodstream infection (BSI) during extracorporeal membrane oxygenation (ECMO). Methods: This retrospective cohort consisted of 202 neonates treated with ECMO from 1989 to 1998 at the author' institution. Data collected included patient demographics, primary and secondary diagnoses, white blood cell counts, antibiotic usage, presence of central lines, operative procedures, and outcome. Surveillance blood cultures were drawn daily from the circuit using sterile technique to identify acquired pathogens. Statistical analyses included logistic regression, Cox proportional regression analysis, and discriminate analysis. Results: There were 1,245 blood cultures drawn on 202 patients (6.2 cultures per patient), and a nosocomial BSI was identified in 7 patients (3.4%) during this 10-year span. These were infections that were neither present nor incubating on admission. Pre-ECMO diagnoses of patients who had a nosocomial BSI while on bypass included group B beta-hemolytic streptococcal sepsis (n = 2), herpes simplex viral sepsis (n = 1), congenital diaphragmatic hernia (n = 2), persistent pulmonary hypertension (n = 1), and congenital heart disease (n = 1). The median time on ECMO before obtaining a positive culture was 390 hours. The infectious agents responsible for these BSIs included Staphylococcus epidermidis (n = 5), Staphylococcus aureus (n = 1), and Escherichia coli (n = 1). The major factor associated with acquiring a nosocomial BSI on ECMO was the duration of bypass (391 v 141 hours, P =.002). Additionally, patients in the BSI group were more likely to have had an arterial catheter in place (16 v 7 days, P =.009) and to have received more screening blood cultures (16 v 6 cultures, P < 001). White blood cell counts, absolute neutrophil counts, and immature/total (I/T) ratios were not useful in predicting a nosocomial BSI. Of the 31 patients who required ECMO for more than 10 days, 7 (23%) had a positive blood culture, and 5 of these 7 infants (71%) died (P =.03). Conclusions: The only predictor of acquiring a nosocomial BSI on ECMO was the duration of support for greater than 10 days. Because classical predictors of infection are unreliable while the patient is on ECMO, the authors suggest that obtaining daily surveillance blood cultures beginning on the tenth day should be performed with prolonged ECMO courses. The authors confirmed previous reports of the association between a prolonged ECMO course and a high mortality rate. However, the authors speculate that, in actuality, the primary diagnosis leads to the prolonged course of support and is the major factor in the infant' demise. J Pediatr Surg 36:487-492. Copyright © 2001 by W.B. Saunders Company.

Monoclonal anti-LPS inner core antibodies protect against experimental hematogenous Haemophilus influenzae type b meningitis

This study tested the protective activity of antibodies to the LPS core of Haemophilus influenzae (Borrelli et al., Infect. Immun. 1995;63: 3683–92) in a hematogenous meningitis model. Meningitis was established by intraperitoneal inoculation of infant rats with H. influenzae type b (Hib). The severity of infection was determined by daily assessment of mortality, symptoms of disease and weight changes. Mortality occurred rapidly after infection with 105cfu/rat and most animals died within 24 h. At a lower infection dose (104cfu/rat) the rats survived, but developed symptoms of disease such as tremor, hypothermia, lethargy and anorexia within 12–72 h post challenge. Surviving animals showed decreased weight gain. Bacteremia was detected by daily blood-cultures in 10/10 rats and cleared 6 days after inoculation. The monoclonal anti-LPS antibody MAHI 3 was used in passive protection studies. MAHI 3 increased the survival in the high inoculum group (105cfu/rat) from 10–17% in control animals to 60–90%. At the lower inoculum concentration (104cfu/rat) MAHI 3 treatment reduced the symptoms and blood counts. Intraperitoneal injection of MAHI 3 was more effective than intranasal injection as shown by the effect on bacteremia. We conclude that anti-LPS antibodies can protect against mortality caused by hematogenous Hib infections in infant rats.

The Incidence of Percutaneous Central Venous Catheter (PCVC) Thrombosis in High Risk Neonates, and the Relationship of Thrombosis to the Occurrence and Persistence of Bacteremia 1420

Percutaneously inserted central venous catheters (PCVCs) are commonly used in high risk neonates, but may be complicated by the formation of thrombi in the central veins or right atrium, and/or the occurrence of foreign-body induced bacterial blood stream infection. The purpose of this study is to determine the incidence of PCVC-related, central vein and/or right atrial thrombosis in neonates. In addition, the study will assess the relationship of thrombus formation to the subsequent development of bacterial blood stream infection, and determine if the presence of a thrombus is associated with failure of antibiotic treatment to eradicate bacteremia. To date, 47 neonates(mean birth weight 1139.4 grams, mean gestational age 28.1 weeks) have been enrolled in the study. In all subjects, immediately post insertion, a blood culture was drawn from the PCVC. Within 72 hours of insertion, a baseline 2-D echocardiogram with color flow Doppler study was performed. Thereafter, while the catheter was in place, blood cultures were drawn and a follow-up 2-D echocardiogram/color flow Doppler study was done once weekly. If a positive blood culture was detected, two additional, quantitative blood cultures (one from the PCVC; one from a peripheral vein) were obtained prior to initiating antibiotic therapy, and a 2-D echocardiogram/color flow Doppler study was performed within 24 hours. Following initiation of antibiotic therapy, a single, daily blood culture was obtained from the PCVC or peripheral vein depending on access, until three consecutive, daily blood cultures showed no bacterial growth. The median duration of PCVC lines was 37 days. Four neonates(0.09%) had positive blood cultures, at a mean of 25.3 days post-insertion. Neonates had a median of 5 blood cultures performed. Only 1 neonate (0.02%) had evidence of thrombus formation on echocardiogram at 10 days post-insertion. Neonates are continuing to be enrolled in this study. Based on this preliminary data, it appears that, despite the fact that in our unit PCVC lines are not changed, PCVC-related bacteremia and thrombosis are rare complications.

Effects of granulocyte colony-stimulating factor in severe pancreatitis

The effect of granulocyte colony-stimulating factor (G-CSF) on the rate of secondary infections in acute pancreatitis was evaluated in a canine model. Infectious complications are the major determinant of morbidity and mortality in severe pancreatitis. Bacterial translocation has been shown to be a cause of these secondary infections. The relative immunosuppression found with pancreatitis may promote translocation and the spread of bacteria to the pancreas. Thirty-four mongrel dogs were studied. Pancreatitis was induced in 18 dogs; 9 were treated with 100 micrograms G-CSF/day and 9 were given only saline solution. Laparotomy alone was done in 16 dogs of which one half were given 100 micrograms G-CSF/day and one half were given saline solution. Daily blood counts and cultures were obtained. All dogs were killed on day 7, and the mesenteric lymph nodes, pancreas, liver, spleen, and peritoneal fluid were cultured and studied histologically. G-CSF caused a significant and sustained increase in mature granulocytes in dogs given pancreatitis. No difference was found in the rate of translocation to mesenteric lymph nodes in dogs given G-CSF (n = 4) versus dogs given saline solution (n = 6). However, a significant decrease occurred in the spread of bacteria to distant sites in dogs given G-CSF (1 versus 15, p < 0.05). Although G-CSF does not decrease the rate of translocation, it does decrease the rate of distant infection in severe acute pancreatitis.

Persistent Bacteremia Due to Coagulase-Negative Staphylococci in Low Birth Weight Neonates

During a 6-month period in 1987, 13 low birth weight neonates without indwelling central intravascular catheters had persistent (positive blood cultures for greater than or equal to 6 days) coagulase-negative staphylococcal bacteremia despite adequate antibiotic therapy. Daily blood cultures remained persistently positive for a mean of 13 days (range 6 to 25 days). This group of infants was compared with other low birth weight infants with similar birth weights and nonpersistent coagulase-negative staphylococcal bacteremia, defined as two or more positive blood cultures accompanied by supporting clinical manifestations of sepsis. During this period, coagulase-negative staphylococcal represented 29% of all bacteremias, and 33% of coagulase-negative staphylococcal bacteremias were persistent. Other than soft tissue abscesses, none of the infants with persistent coagulase-negative staphylococcal bacteremia had a defined focus of infection. Abdominal distention (P = .001) and thrombocytopenia (P less than .03) occurred significantly more frequently in the patients with persistent coagulase-negative staphylococcal bacteremia than in those with nonpersistent bacteremia. Of the 13 patients with persistent coagulase-negative staphylococcal bacteremia, 2 received methicillin and 11 received vancomycin. No antibiotic tolerance to either antibiotic could be demonstrated. Serum concentrations of vancomycin far exceeded the minimum bactericidal concentration in all cases in which vancomycin was prescribed. No in vitro differences could be demonstrated between persistent and nonpersistent coagulase-negative staphylococcal strains for slime production, biotype, proteins from modified whole cell lysates developed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and opsonophagocytosis by adult neutrophils in the presence of pooled human sera. Additionally, plasmid profile analysis and phage typing revealed no common strain causing the persistent bacteremia.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of intrauterine challenge with [formula omitted][formula omitted] serovar [formula omitted] on fertility in cattle

The purpose of this study was to determine the effects of Leptospira interrogans serovar hardio on fertility in cattle. Twenty seronegative mature dairy cows were assigned to two groups. Group I (challenged cows) was bred by a seronegative bull followed by intrauterine infusion (within 30 minutes) of Leptospira interrogans serovar hardjo . Group II was bred by the same bull followed by intrauterine infusion of 5 ml of sterile culture medium. Blood samples were collected at two-day intervals to monitor serum antibody titers. Daily blood cultures for 10 days and weekly urine cultures for five weeks were performed to monitor the animals for leptospiremia and leptospiuria. Cows were slaughtered 35 days post-breeding, and their reproductive tracts were examined. All animals remained clinically normal following intrauterine challenge. There was no difference in pregnancy rates (Group I, 7 10 ; Group II, 6 10 ). All embryos, reproductive tracts, and kidneys appeared normal. A microscopic agglutination test (MA) showed that 4 of 10 challenged cows developed serum antibody titers between 8 and 20 days after challenge. However, on the basis of the hamster passive protection test, all challenged cows had serum antibodies present. All blood and urine cultures were negative through the experimental period, as were the final kidney and uterine cultures. In a second experiment, six seronegative cows were infused with killed microorganisms immediately after insemination. Results of a microscopic agglutination test and a hamster passive protection test indicated that these cows did not develop humoral antibodies against serovar hardjo . These results indicated that intrauterine inoculation of Leptospira interrogans serovar hardjo (hamster-adapted strain) following breeding did not affect pregnancy rates despite an intrauterine challenge which caused the development of humoral antibodies.

Role of serial microbiologic surveillance and clinical evaluation in the management of cancer patients with fever and granulocytopenia

Blood and surveillance body cultures are frequently used to monitor potential infectious complications in febrile cancer patients. However, such cultures are costly and their value unclear when patients are already being treated with antibiotics. We prospectively studied all patients who became febrile (oral temperature > 38 °C three times over a 24-hour period or > 38.5 °C once) and granulocytopenic (less than 500 polymorphonuclear leukocytes per mm 3) during a four-year period, and evaluated the value of clinical assessment and microbiologic surveillance in patient management. Two hundred and seventy-one patients who experienced 652 episodes were entered into study. All patients had routine examination, chest radiograph, and surveillance cultures of nose, throat, urine, stool and at least two preantibtotic blood cultures. According to their initial evaluation, patients were classified as having an infectious etiology for their fever or as having unexplained fever, and were treated accordingly with specific or empiric antibiotic therapy. Patients remained on study until their polymorphonuclear leukocytes were greater than 500 per mm 3, during which time they had weekly surveillance cultures and daily blood cultures when febrile. Although 62 percent of the patients who became septic were colonized with the infecting organism(s), these cultures were not helpful in initial diagnosis or antibiotic management. Similarly, routine surveillance cultures were not useful in guiding or altering subsequent therapy in patients already receiving antibiotics. Although initially negative, blood cultures became positive in 11 patients who had received antibiotics for a median of 12 days (range three to 37 days). As a result of these blood cultures obtained at follow-up, modification of the antimicrobial regimen was made in seven patients, and six patients survived the episode. The mortality rate for patients in whom positive blood cultures developed while receiving antibiotics was 54 percent compared with a 15 percent mortality rate for patients prior to starting antibiotics (p = 0.01). Although routine body surveillance cultures are costly, insensitive, and unlikely to influence antimicrobial management, serial blood cultures, even in patients receiving antibiotic therapy, can specifically influence therapy and outcome, and may be justifiable for patients receiving maximum supportive care.

Occurrence of Sporadic Bacillemia in Experimental Tuberculosis in Dogs

Wilson in summarizing the work on bacillemia in human tuberculosis up to 1933, concludes that bacillemia, detectable by present methods, is, except as a transitory phenomenon, rarely present until the disease has assumed an acute phase. Because of this discrepancy between the reported rare occurrence of bacillemia and the common demonstration of hematogenous tuberculous lesions at necropsy, it seems important to determine the frequency and significance of bacillemia as a transitory phenomenon in tuberculosis. Corper, using dogs as experimental animals, reports that large doses of tubercle bacilli given intravenously produced a rapidly fatal bacillemia without the formation of tubercles. Smaller doses of tubercle bacilli produced no bacillemia and no tuberculous lesions. A search of the literature reveals no report of daily blood-cultures over a period of several months, which would seem to be the most adequate means of determining the frequency of transitory or sporadic bacillemia. In our experiment, dogs were used because of the relative ease of obtaining an adequate quantity of blood daily for culture, and because the relative resistance of the dog to tuberculosis is more closely parallel to that of the human, than is the low resistance of the rabbit and guinea pig. Experimental tuberculosis was produced in dogs by the intravenous injection of large doses of a virulent human type of tubercle bacilli (H37) in a suspension of Kaolan, mineral oil, and normal saline. This method was found to produce embolic tubercles limited largely to the lungs and tending to heal or to progress slowly. Tuberculous abscesses were produced by injection of a similar suspension of tubercle bacilli into the chest wall of dogs. These lesions tended to break down and discharge for a time and then heal.

Studies of Experimental Arthritis. III. Behavior of Skin Tests.

The purpose of this study was to observe the behavior of skin tests under the conditions of experimental arthritis. One of the questions which a clinical study of chronic rheumatism presents is whether a joint once infected can in itself be a focus from which further exacerbations of the disease may arise. Accordingly, in arranging the experimental conditions under which the subject of bacterial allergy was to be studied, arthritis was produced not only by inoculating animals intravenously but also by inoculating small amounts of bacteria into the joints. The organism used was a laboratory strain of hemolytic streptococcus, preserved by freezing and desiccating the culture. Skin tests were made on the backs of the rabbits, after the hair had been clipped and removed with sodium sulfide. This depilatation was carried out 2 to 3 days before the skin tests were made. The toxic filtrate used was prepared by seeding a 24-hour broth culture of the organisms into about 100 cc. of Harley's toxin media. This was incubated for 5 days, centrifugalized and filtered through a Berkefeld candle. Normal rabbits were found to give no skin reaction following the intradermal injection of 1/10 cc. of these filtrates. Animals so tested were used in these experiments. In the series reported 24 animals were used, the same number being inoculated intravenously as by the intra-articular route. After intravenous injection, rabbits usually develop a positive blood culture. Daily blood cultures then show one of two things. The animal tends to recover and the daily blood culture shows fewer and fewer organisms, or the animal grows rapidly worse with more and more organisms per cc. of blood and soon dies. The rabbits surviving may or may not develop metastatic joint infections.