Kelly J. Henrickson

Viral upper respiratory tract infection and otitis media complication in young children.

Abstract Background. The common cold or upper respiratory infection (URI) is highly prevalent among young children and often results in otitis media (OM). The incidence and characteristics of OM complicating URI due to specific viruses have not been well studied. Methods. We performed a prospective, longitudinal cohort study of 294 healthy children (age range, 6 months to 3 years). Each child was observed for 1 year to assess the occurrence of URI, acute OM (AOM), and OM with effusion (OME) complicating URI due to specific viruses. Results. We documented 1295 URI episodes (5.06 episodes per child-year) and 440 AOM episodes (1.72 episodes per child-year). Virus studies were performed for 864 URI episodes; 63% were virus positive. Rhinovirus and adenovirus were most frequently detected during URI. The overall incidence of OM that complicated URI was 61%, including a 37% incidence of AOM and a 24% incidence of OME. Young age was the most important predictor of AOM that complicated URI. AOM occurred in approximately one-half of children with URI due to adenovirus, respiratory syncytial virus, or coronavirus and in approximately one-third of those with URI due to influenza virus, parainfluenza virus, enterovirus, or rhinovirus. Conclusions. More than 60% of episodes of symptomatic URI among young children were complicated by AOM and/or OME. Young age and specific virus types were predictors of URI complicated by AOM. For young children, the strategy to prevent OM should involve prevention of viral URI. The strategy may be more effective if the priority is given to development of means to prevent URI associated with adenovirus and respiratory syncytial virus.

Prevention of Central Venous Catheter–Related Infections and Thrombotic Events in Immunocompromised Children by the Use of Vancomycin/Ciprofloxacin/Heparin Flush Solution: A Randomized, Multicenter, Double-Blind Trial

PURPOSE To determine whether an antibiotic flush solution containing vancomycin, heparin, and ciprofloxacin (VHC) can prevent the majority of line infections. PATIENTS AND METHODS A prospective double-blind study was performed comparing VHC to vancomycin and heparin (VH) to heparin alone in 126 pediatric oncology patients. RESULTS The 153 assessable lines resulted in 36,944 line days studied. There were 58 blood stream infections (43 gram-positive, 14 gram-negative, and one fungal). Forty were defined as line infections (31 heparin, three VH, six VHC). The time to develop a line infection was significantly increased using either antibiotic flush (VH, P =.011; VHC, P =.036). The rate of total line infections (VH, P =.004; VHC, P =.005), gram-positive line infections (VH, P =. 028; VHC, P =.022), and gram-negative line infections (VH, P =.006; VHC, P =.003) was significantly reduced by either VH or VHC. Sixty-two (41%) of the lines developed 119 occlusion episodes (heparin, 3.99 per 1,000 line days; VHC, 1.75 per 1,000 line days; P =.0005). Neither antibiotic could be detected after flushing, and no adverse events were detected, including increased incidence of vancomycin-resistant Enterococcus colonization or disease. CONCLUSION The use of either VH or VHC flush solution significantly decreased the complications associated with the use of tunneled central venous lines in immunocompromised children and would save significant health care resources.

National disease burden of respiratory viruses detected in children by polymerase chain reaction

Background. The epidemiology of community-acquired respiratory viruses at the Children’s Hospital of Wisconsin between 1996 and 1998 was examined with molecular [multiplex (M) PCR] and standard virologic methods. Methods and results. A total of 3325 patients with lower respiratory infection (LRI) [bronchiolitis (42%), pneumonia (38%) and croup (12%)] were identified. It is estimated that 545 000 LRI hospitalizations occur each year in the United States in children younger than 18 years old (viral, 428 000; pneumonia, 221 000; bronchiolitis, 222 000; croup, 65 000), including a continued increase in bronchiolitis hospitalizations (47.8/1000; <1 year). The most common viruses detected each year in hospitalized children included respiratory syncytial virus (A and B; 117 000), parainfluenza virus (PIV-1 and -2, 48 000; PIV-3, 18 000) and influenza (A and B, 39 000). With multiplex reverse transcription polymerase chain reaction (MPCR), different patient populations demonstrated different LRI epidemiology in relation to specific syndromes and viral causes. At least 21% of LRI hospitalizations were in children with significant medical problems. PIVs were detected much more frequently in immunocompromised children than in previously healthy children (33% vs. 16%). Similarly 15% of respiratory syncytial virus was detected between May and October, mostly in immunocompromised children. Influenza caused 19% of bronchiolitis in previously healthy children, and no virus could be reliably predicted based on clinical presentation, including wheezing. Of children hospitalized for LRI, 40% tested positive for the seven most common respiratory viruses by MPCR. Conclusions. Work is under way to expand the number of viruses detected by MPCR and to determine whether newly discovered viruses, such as human metapneumovirus, contribute to the burden of pediatric LRI hospitalizations.

Prevention of bacteremia attributed to luminal colonization of tunneled central venous catheters with vancomycin-susceptible organisms.

Forty-five children with oncologic or hematologic disorders requiring tunneled central venous catheters (TCVC) for the administration of immunosuppressive therapy were randomized to receive either 10 U/mL heparin (H) (24 patients) or a solution of 10 U/mL H and 25 micrograms/mL vancomycin (H-V) (21 patients) for all catheter flushes. Episodes of fever or suspected sepsis were evaluated to determine whether the addition of vancomycin to the flush solution would alter the incidence of symptomatic bacteremia attributed to luminal colonization of TCVC with vancomycin-susceptible bacteria. Patients were enrolled for 247 +/- 150 days, accounting for a total of 11,095 days of catheter use. Bacteremia attributed to luminal colonization with vancomycin-susceptible organisms occurred in five patients (six infections) receiving H alone compared with zero patients receiving H-V (P = .035). The time to the first episode of bacteremia with vancomycin-susceptible organisms, analyzed by Kaplan-Meier survival curves, was significantly longer in patients receiving H-V (P = .04). There were no differences in the incidence of other infections including bacteremia attributed to luminal colonization with vancomycin-resistant organisms, other bacteremias (including those arising from the catheter exit site), exit-site cellulitis, or fungal infections. No organisms resistant to vancomycin were identified. Vancomycin could not be detected in the peripheral blood of patients receiving vancomycin in the flush solution. No vancomycin-related toxicities were noted. We conclude that the use of an H-V flush solution in immunocompromised patients with TCVC can decrease the frequency of bacteremia attributed to luminal colonization with vancomycin-susceptible bacteria.

Evaluation of the Hexaplex Assay for Detection of Respiratory Viruses in Children

ABSTRACT The Hexaplex assay (Prodesse, Inc., Milwaukee, Wis.) is a multiplex reverse transcriptase (RT)-PCR assay for the detection of parainfluenza virus types 1, 2, and 3, respiratory syncytial virus (RSV) types A and B, and influenza virus types A and B. We evaluated the Hexaplex assay in comparison with conventional viral cell cultures and rapid enzyme immunoassays (EIAs) for RSV (Directigen; Becton Dickinson Inc., Cockeysville, Md.) and influenza A virus (Abbott Test Pack; Abbott Laboratories, Abbott Park, Ill.) for the detection of respiratory viruses from pediatric respiratory specimens obtained from children seen at Childrens Hospital of Wisconsin from December 1997 through May 1998. A total of 363 respiratory specimens were evaluated. The tissue culture prevalence of parainfluenza virus during this period of time was low (1.1%). The sensitivity, specificity, and positive and negative predictive value of Hexaplex compared to tissue culture for the detection of parainfluenza virus were 100, 95.8, 19.0, and 100%, respectively. Only one specimen was determined to contain influenza B virus by Hexaplex; it was tissue culture negative. A specimen was considered to contain RSV or influenza A virus when it was either culture positive or culture negative but Hexaplex and EIA positive. Prior to the analysis of discrepant results, the sensitivity, specificity, and positive and negative predictive value for the detection of RSV were 91.2, 100, 100, and 98.0%, respectively, for tissue culture; 84.5, 100, 100, and 96.6% for EIA; and 98.5, 91.5, 72.8, and 99.6% for Hexaplex, respectively. The sensitivity, specificity, and positive and negative predictive value for the detection of influenza A virus prior to the analysis of discrepant results were 100, 100, 100, and 100%, respectively, for culture, 78.0, 100, 100, and 89.4% for EIA, respectively, and 95.1, 94.1, 67.2, and 99.3% for Hexaplex, respectively. Culture- and/or EIA-negative, Hexaplex-positive specimens were analyzed by a second RT-PCR assay which used primers specific for a different genomic region than that used in the Hexaplex assay. After analysis of these discrepant results, the sensitivity, specificity, and positive and negative predictive value for the detection of RSV were 74.3, 100, 100, and 93.5%, respectively, for tissue culture; 70.3, 100, 100, and 92.5% for EIA; and 98.6, 97.4, 91.2, and 99.6% for Hexaplex. The sensitivity, specificity, and positive and negative predictive value for the detection of influenza A virus were 83.3, 100, 100, and 97.4%, respectively, for tissue culture; 69.4, 100, 100, and 83.3% for EIA; and 95.8, 98.7, 92.0, and 99.3% for Hexaplex. Hexaplex is a rapid, sensitive, and specific method for the detection of the seven most common respiratory viruses in children.

A vancomycin-heparin lock solution for prevention of nosocomial bloodstream infection in critically ill neonates with peripherally inserted central venous catheters: a prospective, randomized trial.

Objective.Critically ill neonates are at high risk for vascular catheter–related bloodstream infection (CRBSI), most often caused by coagulase-negative staphylococci. Most CRBSIs with long-term devices derive from intraluminal contaminants. The objective of this study was to ascertain the safety and the efficacy of a vancomycin-heparin lock solution for prevention of CRBSI. Methods.A prospective, randomized double-blind trial was conducted during 2000–2001 at a community hospital level III NICU. Very low birth weight and other critically ill neonates with a newly placed peripherally inserted central venous catheter were randomized to have the catheter locked 2 or 3 times daily for 20 or 60 minutes with heparinized normal saline (n = 43) or heparinized saline that contained vancomycin 25 μg/mL (n = 42). The origin of each nosocomial bloodstream infection (BSI) was studied by culturing skin, catheter hubs, and implanted catheter segments and blood cultures, demonstrating concordance by restriction-fragment DNA subtyping. Surveillance axillary and rectal cultures were performed to detect colonization by vancomycin-resistant organisms. The main outcome measures were (1) CRBSIs and (2) colonization or infection by vancomycin-resistant Gram-positive bacteria. Results.Two (5%) of 42 infants in the vancomycin-lock group developed a CRBSI as compared with 13 (30%) of 43 in the control group (2.3 vs 17.8 per 1000 catheter days; relative risk: 0.13; 95% confidence interval: 0.01–0.57). No vancomycin-resistant enterococci or staphylococci were recovered from any cultures. Vancomycin could not be detected in the blood of infants who did not receive systemic vancomycin therapy. Twenty-six neonates (8 vancomycin-lock group, 18 control group) had at the end of a catheter-lock period asymptomatic hypoglycemia that resolved promptly when glucose-containing intravenous fluids were restarted. Conclusions.Prophylactic use of a vancomycin-heparin lock solution markedly reduced the incidence of CRBSI in high-risk neonates with long-term central catheters and did not promote vancomycin resistance but was associated with asymptomatic hypoglycemia. The use of an anti-infective lock solution for prevention of CRBSI with long-term intravascular devices has achieved proof of principle and warrants selective application in clinical practice.

Advances in the laboratory diagnosis of viral respiratory disease.

Background In recent years significant advances in the laboratory diagnostics available to detect respiratory viral infections have been achieved. Methods This article presents the types of diagnostic methods currently available to the practitioner, as well as those on the horizon. The article covers tissue culture, serology and direct examination as well as some rapid diagnostic techniques and molecular assays, previewing developing new technology. Conclusions Laboratory diagnosis will likely be clinically useful in some but not all cases of viral infection. As new diagnostic methods become widely available, it is increasingly important to develop guidelines for laboratory testing when viral illness is suspected.

Detection of 11 Common Viral and Bacterial Pathogens Causing Community-Acquired Pneumonia or Sepsis in Asymptomatic Patients by Using a Multiplex Reverse Transcription-PCR Assay with Manual (Enzyme Hybridization) or Automated (Electronic Microarray) Detection

ABSTRACT Community-acquired pneumonia (CAP) and sepsis are important causes of morbidity and mortality. We describe the development of two molecular assays for the detection of 11 common viral and bacterial agents of CAP and sepsis: influenza virus A, influenza virus B, respiratory syncytial virus A (RSV A), RSV B, Mycoplasma pneumoniae, Chlamydophila pneumoniae, Legionella pneumophila, Legionella micdadei, Bordetella pertussis, Staphylococcus aureus, and Streptococcus pneumoniae. Further, we report the prevalence of carriage of these pathogens in respiratory, skin, and serum specimens from 243 asymptomatic children and adults. The detection of pathogens was done using both a manual enzyme hybridization assay and an automated electronic microarray following reverse transcription and PCR amplification. The analytical sensitivities ranged between 0.01 and 100 50% tissue culture infective doses, cells, or CFU per ml for both detection methods. Analytical specificity testing demonstrated no significant cross-reactivity among 19 other common respiratory organisms. One hundred spiked “surrogate” clinical specimens were all correctly identified with 100% specificity (95% confidence interval, 100%). Overall, 28 (21.7%) of 129 nasopharyngeal specimens, 11 of 100 skin specimens, and 2 of 100 serum specimens from asymptomatic subjects tested positive for one or more pathogens, with S. pneumoniae and S. aureus giving 89% of the positive results. Our data suggest that asymptomatic carriage makes the use of molecular assays problematic for the detection of S. pneumoniae or S. aureus in upper respiratory tract secretions; however, the specimens tested showed virtually no carriage of the other nine viral and bacterial pathogens, and the detection of these pathogens should not be a significant diagnostic problem. In addition, slightly less sensitive molecular assays may have better correlation with clinical disease in the case of CAP.

Diagnostic assays for respiratory syncytial virus disease.

Respiratory syncytial virus (RSV) infection in the United States and worldwide is a major cause of morbidity and mortality and of outpatient visits, hospitalizations, and increased healthcare costs. Effective diagnosis of viral respiratory infections, as well as recognition and understanding of the benefits and limitations of diagnostic laboratory testing, is essential. Serology is not useful for diagnosing acute respiratory illness. Antigen-based assays are widely available, easy to use, provide rapid results, and are inexpensive; however, they are less sensitive than cell culture utilizing good specimen collection and processing techniques. Cell culture, which was previously considered the gold standard for identification of respiratory viruses, in many settings is being replaced by nucleic acid amplification assays that have even greater sensitivity and provide more rapid results. Although available chiefly at large hospitals and reference laboratories, molecular assays may fulfill the need for more sensitive and rapid diagnosis of illnesses caused by respiratory viruses. The seasonality of RSV as measured by nucleic acid amplification-based assays appears to be broader with better identification of patient populations that harbor RSV between yearly epidemic peaks compared with the seasonality of RSV as measured by the older techniques. As these new diagnostic methodologies emerge, guidelines will be needed to direct their appropriate use in the diagnostic laboratory.

The Pneumoplex Assays, a Multiplex PCR-Enzyme Hybridization Assay That Allows Simultaneous Detection of Five Organisms, Mycoplasma pneumoniae, Chlamydia (Chlamydophila) pneumoniae, Legionella pneumophila, Legionella micdadei, and Bordetella pertussis, and Its Real-Time Counterpart

ABSTRACT Respiratory disease caused by atypical bacteria remains an important cause of morbidity and mortality for adults and children, despite the widespread use of effective antimicrobials agents. Culture remains the “gold standard” for the detection of these agents. However, culture is labor-intensive, takes several days to weeks for growth, and can be very insensitive for the detection of some of these organisms. Newer singleplex PCR diagnostic tests are sensitive and specific, but multiple assays would be needed to detect all of the common pathogens. Therefore, we developed the Pneumoplex assays, a multiplex PCR-enzyme hybridization assay (the standard assay) and a multiplex real-time assay to detect the most common atypical pathogens in a single test. Primer and probe sequences were designed from conserved regions of specific genes for each of these organisms. The limits of detection were as follows: for Bordetella pertussis, 2 CFU/ml; for Legionella pneumophila (serotypes 1 to 15) and Legionella micdadei, 9 and 80 CFU/ml, respectively; for Mycoplasma pneumoniae, 5 CFU/ml; and for Chlamydia (Chlamydophila) pneumoniae, 0.01 50% tissue culture infective doses. Recombinant DNA controls for each of these organisms were constructed, and the number of copies for each DNA control was calculated. The Pneumoplex could detect each DNA control down to 10 copies/ml. The analytical specificity demonstrated no cross-reactivity between 23 common respiratory pathogens. One hundred twenty-five clinical bronchoalveolar lavage fluid samples tested by the standard assay demonstrated that the Pneumoplex yielded a sensitivity and a specificity of 100 and 98.5%, respectively. This test has the potential to assist clinicians in establishing a specific etiologic diagnosis before initiating therapy, to decrease hospital costs, and to prevent inappropriate antimicrobial therapy.