Pharmacokinetics of Cefazolin and Vancomycin in Infants Undergoing Open-Heart Surgery With Cardiopulmonary Bypass.

BACKGROUND: Gram-positive bacteria account for nearly three-quarters of all surgical site infections. Antibiotic prophylaxis against these bacteria with cephalosporins or, in select circumstances, with vancomycin is considered standard of care for prevention of surgical site infections. There is little evidence to describe the optimal dosing regimen for surgical site infection prophylaxis in infants undergoing cardiac surgery, and a great deal of institutional variability exists in dosing prophylactic antibiotics. We designed this study to describe an optimal dose regimen for cephalosporin and vancomycin based on pharmacokinetic evidence for infant open-heart surgery on cardiopulmonary bypass. METHODS: Two separate cohorts of infants undergoing cardiac surgery with cardiopulmonary bypass were evaluated. Plasma concentrations of vancomycin (cohort 1, N = 10) and cefazolin (cohort 2, N = 10) were measured, and mixed-effects pharmacokinetic models were constructed for each drug. Simulations of various dosing regimens were performed to describe an appropriate dosing regimen necessary to maintain antibiotic concentrations above the susceptibility cutoff for staphylococci. RESULTS: Both cefazolin and vancomycin plasma concentration versus time profiles were characterized by a 2-compartment model. Subject weight was a significant covariate for V1 for vancomycin. Subject age was a significant covariate for V1 for cefazolin. Cardiopulmonary bypass did not influence concentration versus time profiles. Simulations demonstrated that a 1-hour vancomycin infusion (15 mg·kg), repeated every 12 hours and a 10-minute infusion of cefazolin (30 mg·kg), repeated every 4 hours maintained plasma concentrations above 4 µg·mL and 16 µg·mL, for vancomycin and cefazolin, respectively. Both concentrations are above the minimum inhibitory concentration 90 for most susceptible staphylococci. CONCLUSIONS: Prophylactic treatment of vancomycin 15 mg·kg infused >1 hour with 12-hour redosing and cefazolin 30 mg·kg infused >10 minutes with 4-hour redosing will maintain serum levels of each antibiotic above the susceptibility cut-offs for susceptible staphylococci in infants undergoing cardiac surgery. Cefazolin levels may be adequate for some, but not all, Gram-negative bacteria. The effect of cardiopulmonary bypass on pharmacokinetics is negligible.

Valganciclovir for symptomatic congenital cytomegalovirus disease.

BACKGROUND: The treatment of symptomatic congenital cytomegalovirus (CMV) disease with intravenous ganciclovir for 6 weeks has been shown to improve audiologic outcomes at 6 months, but the benefits wane over time. METHODS: We conducted a randomized, placebo-controlled trial of valganciclovir therapy in neonates with symptomatic congenital CMV disease, comparing 6 months of therapy with 6 weeks of therapy. The primary end point was the change in hearing in the better ear ("best-ear" hearing) from baseline to 6 months. Secondary end points included the change in hearing from baseline to follow-up at 12 and 24 months and neurodevelopmental outcomes, with each end point adjusted for central nervous system involvement at baseline. RESULTS: A total of 96 neonates underwent randomization, of whom 86 had follow-up data at 6 months that could be evaluated. Best-ear hearing at 6 months was similar in the 6-month group and the 6-week group (2 and 3 participants, respectively, had improvement; 36 and 37 had no change; and 5 and 3 had worsening; P=0.41). Total-ear hearing (hearing in one or both ears that could be evaluated) was more likely to be improved or to remain normal at 12 months in the 6-month group than in the 6-week group (73% vs. 57%, P=0.01). The benefit in total-ear hearing was maintained at 24 months (77% vs. 64%, P=0.04). At 24 months, the 6-month group, as compared with the 6-week group, had better neurodevelopmental scores on the Bayley Scales of Infant and Toddler Development, third edition, on the language-composite component (P=0.004) and on the receptive-communication scale (P=0.003). Grade 3 or 4 neutropenia occurred in 19% of the participants during the first 6 weeks. During the next 4.5 months of the study, grade 3 or 4 neutropenia occurred in 21% of the participants in the 6-month group and in 27% of those in the 6-week group (P=0.64). CONCLUSIONS: Treating symptomatic congenital CMV disease with valganciclovir for 6 months, as compared with 6 weeks, did not improve hearing in the short term but appeared to improve hearing and developmental outcomes modestly in the longer term. (Funded by the National Institute of Allergy and Infectious Diseases; ClinicalTrials.gov number, NCT00466817.).

Fatal West Nile Virus Encephalitis in a Heart Transplant Recipient.

The diagnosis of encephalitis is particularly challenging in immunocompromised patients. We report here a case of fatal West Nile virus encephalitis confounded by the presence of budding yeast in the cerebrospinal fluid (CSF) from a patient who had undergone heart transplantation for dilated cardiomyopathy 11 months prior to presentation of neurologic symptoms.

Evaluation of febrile, nonneutropenic pediatric oncology patients with central venous catheters who are not given empiric antibiotics.

OBJECTIVE: To evaluate the practice of empiric antibiotics for febrile, nonneutropenic pediatric oncology patients with a central venous catheter (CVC) in place. STUDY DESIGN: Episodes of fever without neutropenia (absolute neutrophil count [ANC] ≥500 cells/mm(3)) were reviewed retrospectively in pediatric oncology patients with a CVC undergoing chemotherapy. Characteristics and symptoms were compared between patients with bacteremia and patients without bacteremia. RESULTS: A total of 392 episodes of nonneutropenic fever in 138 subjects (52 females; 38%) were reviewed. In this cohort, the median age at an episode was 7 years, and the majority of patients had a diagnosis of acute leukemia (54%). Median ANC was 3100 cells/mm(3) (IQR, 1570-5980 cells/mm(3)). Median temperature was 38.7°C (IQR, 38.3-39.2°C). Twenty-four infectious episodes (6%) occurred in 18 subjects, and 5 CVCs required removal; all patients requiring removal admitted and received antibiotics owing to chills. There were no significant difference in age, sex, or ANC between patients with bacteremia and those without bacteremia; however, mean temperature was higher in the patients with bacteremia (39.4°C vs 38.7°C; P = .003). No deaths due to sepsis occurred, and no CVCs were removed because antibiotics were not administered empirically. CONCLUSION: Our practice of observing pediatric oncology patients undergoing chemotherapy with CVCs who are not neutropenic does not appear to lead to increased serious adverse outcomes and avoids antibiotic exposure for >90% of patients without a bacterial infection.

Staphylococcal infections in children, California, USA, 1985-2009.

We conducted a retrospective, observational, population-based study to investigate the effect of staphylococcal infections on the hospitalization of children in California during 1985-2009. Hospitalized children with staphylococcal infections were identified through the California Office of Statewide Health Planning and Development discharge database. Infections were categorized as community onset, community onset health care-associated, or hospital onset. Infection incidence was calculated relative to all children and to those hospitalized in acute-care facilities. A total of 140,265 records were analyzed. Overall incidence increased from 49/100,000 population in 1985 to a peak of 83/100,000 in 2006 and dropped to 73/100,000 in 2009. Staphylococcal infections were associated with longer hospital stays and higher risk for death relative to all-cause hospitalizations of children. The number of methicillin-resistant Staphylococcus aureus infections increased, and the number of methicillin-susceptible S. aureus infections remained unchanged. Children <3 years of age, Blacks, and those without private insurance were at higher risk for hospitalization.

Nontuberculous mycobacteria infections in immunocompromised patients: single institution experience.

Disseminated infection due to nontuberculous Mycobacterium (NTM) species is rare in pediatrics. Here we report 6 infections affecting 5 patients at a single institution in an immunocompromised population of pediatric oncology and stem cell transplant recipients. The patients presented within a 1-year period with catheter-associated bacteremia. New pulmonary nodules were noted in 4 of the 5 patients. All of the infections were due to rapidly growing NTM. Patients were successfully treated with removal of the infected catheter and combination antibiotic therapy. There are currently no consensus guidelines for treatment of NTM infections in this population, and a therapeutic approach is presented here.

Liposomal amphotericin B associated with severe hyperphosphatemia.

We report 4 patients who developed hyperphosphatemia while receiving liposomal amphotericin B to treat an invasive fungal infection. Resolution of the hyperphosphatemia occurred after transition to amphotericin B lipid complex. This phenomenon may occur more commonly in patients with mild to moderate renal insufficiency.

Mycobacterium bovis disease in a pediatric renal transplant patient.

We describe a pediatric renal transplant patient with Mycobacterium bovis disease who was successfully treated using an antituberculosis regimen that included rifampin. We discuss the history of M. bovis and the diagnosis and management of M. bovis infection in renal transplant patients.

Bone and joint infections in children.

Bone and joint infections are a significant cause of morbidity in infants and young children. Although many principles regarding pathogenesis, diagnosis, and treatment of infection have remained constant over the years, other aspects of this important pediatric diagnosis are continuing to evolve. This article reviews current information regarding pathogenesis, epidemiology, and microbiology of pediatric bone and joint infections and the clinical presentation, diagnosis, and treatment of these infections.

Comparison of conventional viral cultures with direct fluorescent antibody stains for diagnosis of community-acquired respiratory virus infections in hospitalized children.

OBJECTIVE: Because of the widespread availability of rapid viral antigen testing, many institutions never adopted a routine practice of ordering viral cultures to detect community-acquired respiratory viruses (CRVs). The ease of performing complete viral studies in our on site laboratory allowed us to assess the clinical implications of the absence of conventional culture results in previously healthy hospitalized children with CRV infections. METHODS: From June 1997 through May 2000, the results of direct immunofluorescence assay (DFA) of 1069 nasopharyngeal swab (NP) specimens were compared with simultaneously inoculated conventional tube cell cultures for detection of CRVs. In addition the medical records of 140 previously healthy infants and children hospitalized for management of lower respiratory tract infections caused by culture-proved CRVs were reviewed. RESULTS: Viruses were isolated or detected by DFA or viral culture or both in 468 (30%) of the 1557 NP samples evaluated. The most common CRV isolated was respiratory syncytial virus (49%), followed by parainfluenza viruses (15%), influenza A viruses (14%), rhinoviruses (8%), adenoviruses (4%), enteroviruses (4%) and influenza B viruses (1%). Of the 1069 NP specimens for which both viral culture and rapid antigen testing were performed, 190 specimens were DFA-positive and culture-positive, 7 specimens were DFA-positive and culture-negative, 35 specimens were DFA-negative and culture-positive and 837 specimens were DFA-negative and culture-negative. The overall sensitivity, specificity, positive predictive value and negative predictive value of DFA were 84, 99, 96 and 96%, respectively. Of the 140 hospitalized patients with culture-proved viral cultures (89 respiratory syncytial virus, 22 influenza A, 20 parainfluenza virus and 9 adenovirus), the mean duration of hospital stay was 3.6 days, and the mean time for viral cultures to become positive was 7.7 days (P < 0.001, signed rank test). One hundred twenty (86%) viral cultures did not become positive until after the patient had been discharged from the hospital. In no case was the clinical decision regarding the patient's treatment or discharge from the hospital based on the results of viral culture. CONCLUSIONS: We conclude that positive viral cultures have no impact on clinical decision making and management of healthy children during hospitalization for illness attributable to community-acquired respiratory viruses.

Evaluation of serial urine viral cultures for the diagnosis of cytomegalovirus infection in neonates and infants.

Cytomegalovirus (CMV) is the most common cause of congenital infection worldwide. Urine viral culture is the standard for CMV diagnosis in neonates and infants. The objectives of this study were to compare the performance of serial paired rapid shell vial cultures (SVC) and routine viral cultures (RVC), and to determine the optimal number of cultures needed to detect positive cases. From 2001 to 2011, all paired CMV SVC and RVC performed on neonates and infants less than 100 days of age were recorded. Testing episodes were defined as sets of cultures performed within 7 days of one another. A total of 1264 neonates and infants underwent 1478 testing episodes; 68 (5.4%) had at least one episode with a positive CMV culture. In episodes where CMV was detected before day 21 of life, the first specimen was positive in 100% (16/16) of cases. When testing occurred after 21 days of life, the first specimen was positive in 82.7% (43/52) of cases, requiring three cultures to reach 100% detection. The SVC was more prone to assay failure than RVC. Overall, when RVC was compared to SVC, there was 86.0% positive agreement and 99.9% negative agreement. In conclusion, three serial urine samples are necessary for detection of CMV in specimens collected between day of life 22 and 99, while one sample may be sufficient on or before day of life 21. Though SVC was more sensitive than RVC, the risk of SVC failure supports the use of multimodality testing to optimize detection.

Pediatric and neonatal Staphylococcus aureus bacteremia: epidemiology, risk factors, and outcome.

OBJECTIVE: To evaluate the impact of methicillin-resistant Staphylococcus aureus on the prevalence of S. aureus bloodstream infection among children. METHODS: Retrospective analysis of demographic data, risk factors for infection, and clinical outcomes for children (age, less than 18 years) with S. aureus bacteremia hospitalized at a children's hospital during 2001-2006. RESULTS: We identified 164 episodes of S. aureus bacteremia among 151 children. The prevalence of bacteremia due to methicillin-susceptible S. aureus during 2001-2003 was approximately the same as that during 2004-2006 (29 and 30 cases, respectively, per 10,000 hospitalized children [hereafter, "per 10,000 hospitalizations"]), but the prevalence of bacteremia due to methicillin-resistant S. aureus increased from 4 to 11 cases, respectively, per 10,000 hospitalizations (P=.015). A total of 48% of infections involved children who had S. aureus-positive blood cultures less than 3 days after hospital admission. Seventy-four percent of these children had a preexisting comorbidity. When the prevalence of S. aureus bacteremia was stratified by race, sex, or age, neonates hospitalized at birth and Hispanic children had significantly reduced risks of infection. Children younger than 1 year of age (excluding neonates hospitalized at birth) had an increased prevalence of hospital-onset S. aureus bacteremia. There was a disproportionate increase in the risk of S. aureus bacteremia for each additional week of hospitalization among children with hospital-onset S. aureus bacteremia. Children with methicillin-resistant S. aureus bacteremia had a longer hospital stay, were transferred to another facility at a greater rate than they were discharged home, and had a greater mortality rate, compared with children with methicillin-susceptible S. aureus bacteremia. CONCLUSION: This study documents the prevalence of S. aureus bacteremia among children with a high risk for acquiring this infection, and it describes populations of children who are at higher risk for bacteremia due to either methicillin-susceptible or methicillin-resistant S. aureus. Methods to improve prevention of S. aureus bacteremia are needed for children with healthcare-associated risk factors for S. aureus bacteremia.

Severe cryptosporidiosis in a seven-year-old renal transplant recipient: case report and review of the literature.

Cryptosporidium is an intracellular protozoa that can cause gastroenteritis in humans. In immunocompromised hosts, infection can be severe, leading to life-threatening persistent diarrhea. There is limited experience in treating this infection in solid organ transplants. Although newer drugs active against Cryptosporidium exist, they are only licensed in the USA for treatment of immunocompetent hosts. Here we describe a seven-year-old renal transplant recipient with severe cryptosporidiosis. He had a protracted course of diarrhea of up to 2 L/day. He was successfully managed with combination antimicrobial therapy including nitazoxanide, paromomycin, and azithromycin. In conjunction with this regimen, he had a reduction in immunosuppression and complete bowel rest. His stool pattern normalized in four weeks and he has had no recurrence after six months of follow up.

Impaired accumulation and function of memory CD4 T cells in human IL-12 receptor beta 1 deficiency.

Defects in IL-12 production or IL-12 responsiveness result in a vulnerability to infection with non-viral intracellular organisms, but the immunological mechanisms responsible for this susceptibility remain poorly understood. We present an immunological analysis of a patient with disseminated Salmonella enteritidis and a homozygous splice acceptor mutation in the IL-12Rbeta1-chain gene. This mutation resulted in the absence of IL-12Rbeta1 protein on PBMC and an inability of T cells to specifically bind IL-12 or produce IFN-gamma in response to either IL-12 or IL-23. The accumulation of memory (CD45R0(high)) CD4 T cells that were CCR7(high) (putative central memory cells) was normal or increased for age. Central memory CD4 T cells of the patient and age-matched controls were similar in having a low to undetectable capacity to produce IFN-gamma after polyclonal stimulation. In contrast, the patient had a substantial decrease in the number of CCR7(neg/dull) CD45R0(high) memory CD4 T cells (putative effector memory cells), and these differed from control cells in having a minimal ability to produce IFN-gamma after polyclonal stimulation. Importantly, tetanus toxoid-specific IFN-gamma production by PBMC from the patient was also significantly reduced compared with that in age-matched controls, indicating that signaling via the IL-12Rbeta1-chain is generally necessary for the in vivo accumulation of human memory CD4 T cells with Th1 function. These results are also consistent with a model in which the IL-12Rbeta1 subunit is necessary for the conversion of central memory CD4 T cells into effector memory cells.