Gordon G. Stout

Effect of rapid viral diagnosis on the management of children hospitalized with lower respiratory tract infection.

BACKGROUND Although rapid viral tests are commonly used in children with lower respiratory tract infection, their effect on patient management has not been studied. OBJECTIVES To examine how physicians utilize an enzyme immunoassay for respiratory syncytial virus (RSV EIA) and a centrifugation-enhanced cellular immunofluorescence assay for multiple viral pathogens [viral respiratory panel (VRP)] in children hospitalized with respiratory illness; to determine the effect of testing on length of stay, antibiotic use and costs; and to determine physician attitudes toward RSV testing. DESIGN AND SETTING Prospective study and survey at a large childrens hospital. PATIENTS Previously healthy children < 24 months of age consecutively admitted between January 1 and February 11, 1995, with symptoms of lower respiratory tract infection. RESULTS Of 200 patients 160 were tested by RSV EIA; 92 were positive and 68 were negative. Tested children were younger, more tachypneic and more likely to require oxygen than those not tested. Overall the length of stay was similar in RSV-positive and -negative patients. Although equal proportions of each group were given antibiotic therapy, RSV-positive children received antibiotic therapy for fewer days than RSV-negative children (median 2 vs. 3 days; P = 0.0387). However, a crude cost analysis did not support a strategy of testing all bronchiolitis patients for RSV. Sixty-five of the 68 RSV-negative children were tested for RSV and other pathogens by VRP. In 55 cases the results were not available until after patient discharge and could not have influenced their management. One hundred three physicians caring for children in the study were surveyed. Of 75 respondents almost all thought that RSV EIA results influenced their management of patients and were important to parents. CONCLUSIONS Most children hospitalized with symptoms of lower respiratory tract infection were tested for viral pathogens. The VRP provided little clinically useful information. In contrast RSV EIA results may have been used by clinicians to make antibiotic decisions. Physicians felt that rapid testing for RSV was important.

Susceptibilities of Haemophilus influenzae, Streptococcus pneumoniae, including serotype 19A, and Moraxella catarrhalis paediatric isolates from 2005 to 2007 to commonly used antibiotics

OBJECTIVES The aim of this study was to evaluate susceptibility to common paediatric antibiotics for Streptococcus pneumoniae, non-typeable Haemophilus influenzae and Moraxella catarrhalis isolated from 2005 through 2007. METHODS Microdilution MIC assays were performed using CLSI-approved methods. S. pneumoniae 19A strains were identified by quellung reaction. RESULTS Among 143 non-typeable H. influenzae, 42% produced beta-lactamase. By 2007 breakpoints (PK/PD:CLSI), percentage susceptibility for non-typeable H. influenzae was: ceftriaxone = cefixime = high-dose amoxicillin/clavulanate (all 100%:100%) > standard-dose amoxicillin/clavulanate (91.6%:100%) > cefuroxime axetil (88.1%:99.3%) > cefdinir (83.9%:100%) > trimethoprim/sulfamethoxazole (73.4%:73.4%) >high-dose amoxicillin (58%:58%) > standard-dose amoxicillin (55.2%:58%) > cefprozil (28.7%:83.2%) > cefaclor (3.5%:83.2%) > azithromycin (0%:87.4%). Of 208 S. pneumoniae (42 serotype 19A), 86 were penicillin-susceptible, 60 were penicillin-intermediate and 62 were penicillin-resistant by 2007 CLSI breakpoints. Percentage susceptibility for all S. pneumoniae/19A by PD breakpoints was: ceftriaxone (95.2%/86.1%) > high-dose amoxicillin (89.4%/58.3%) > clindamycin (85%/58.3%) > standard-dose amoxicillin (73.5%/33.3%) > cefuroxime axetil (69.2%/36.1%), cefprozil (67.3%/33.3%) > cefdinir (59.1%/33.3%) > cefixime (57.7%/33.3%) > azithromycin (56.7%/33.3%) > trimethoprim/sulfamethoxazole (50.5%/25%) > penicillin (41.3%/19.4%) > cefaclor (28.8%/8.3%). Percentage M. catarrhalis (n = 62) susceptibility by PK/PD breakpoints was: high-dose amoxicillin/clavulanate = cefixime (100%) > azithromycin (98.4%) > ceftriaxone (96.8%) > standard-dose amoxicillin/clavulanate (88.7%) > cefdinir (80.6%) > cefprozil = cefuroxime axetil (37.1%) > high-dose amoxicillin (11.2%) > cefaclor (6.5%) > standard-dose amoxicillin (4.8%). CONCLUSIONS Despite high rates of beta-lactamase production among non-typeable H. influenzae and M. catarrhalis, multiple oral treatment options exist for non-typeable H. influenzae and M. catarrhalis. Multidrug-resistant serotype 19A S. pneumoniae ( approximately 20%) limits treatment options for ambulatory S. pneumoniae respiratory disease.

Antibodies to the Major Linear Neutralizing Domains of Cytomegalovirus Glycoprotein B Among Natural Seropositives and CMV Subunit Vaccine Recipients

The gB protein (gpUL55) of human cytomegalovirus (CMV) contains C-terminal (AD-1) and N-terminal (AD-2) linear immunodominant neutralizing domains. To measure antibodies to these epitopes, a modified protein (delta-gB) lacking heavily glycosylated intervening regions, the transmembrane domain, and the cytoplasmic domain, was expressed in recombinant baculovirus-infected cells. Eighty-six percent of 600 naturally CMV-seropositive individuals and 93% of 121 gB vaccine recipients had antibodies to delta-gB as detected by enzyme-linked immunosorbent assay (ELISA). The antibody level in vaccinees (median optical density [OD] = 1.73) exceeded that in natural seropositives (median OD = 0.94; p < .0001). Eleven percent of 95 natural seropositives and 7% of 120 gB vaccinees lacked A-gB antibodies but had neutralizing activity. Among subjects with delta-gB antibody, there were weak correlations between antibody level and neutralizing titer. These data suggest that antibodies to linear neutralizing gB domains are highly prevalent in naturally-infected individuals and regularly develop in gB vaccinees. However, for some individuals, discontinuous and/or linear epitopes not represented on delta-gB may be more important in the generation of neutralizing responses.

Nasopharyngeal colonization with heptavalent pneumococcal conjugate vaccine serotypes of Streptococcus pneumoniae with prolonged vaccine dosing intervals.

Introduction: Universal infant heptavalent pneumococcal conjugate vaccine (PCV-7) immunization, dosed near to the originally recommended schedule of a 3-dose series in the first 6 months of life, then a booster between 12 and 15 months, should reduce nasopharyngeal (NP) carriage of Streptococcus pneumoniae (Spn) PCV-7 types. The reduced availability of PCV-7 altered immunization schedules, particularly for third and fourth PCV-7 doses. We evaluated NP colonization in relation to originally recommended intervals and numbers of PCV-7 doses. Methods: Spn from NP cultures of a cohort of 106 normal children, obtained during 20 months of PCV-7 shortage, were identified and serotyped by standard methods. Results: Spn was detected in 153 of 418 cultures (37%). Age, >1 sibling, day-care attendance and prolonged PCV-7 dosing intervals were univariate risks for NP detection of PCV-7 types. PCV-7 strains comprised 7 of 15 (47%) of Spn before the first dose, 28 of 36 (78%) and 27 of 41 (66%), respectively, after the first and second dose and then 16 of 36 (44%) and 11 of 25 (44%) after the third and fourth doses. The risk of NP colonization with PCV-7 types was higher with intervals of >3 months between second and third doses and intervals of >8 months between the third and fourth doses. Multivariate analysis showed prolonged interval after the second and third PCV-7 doses and day-care attendance as risk factors for NP detection of PCV-7 strains. Conclusion: Although PCV-7 serotypes were detected less after third and fourth PCV-7 doses, longer dosing intervals, particularly in day-care attendees, were associated with higher risk of PCV-7 detection in the NP.

PROCESSING OF HUMAN CYTOMEGALOVIRUS GLYCOPROTEIN B IN RECOMBINANT ADENOVIRUS-INFECTED CELLS

Intracellular processing of human cytomegalovirus (HCMV) glycoprotein B (gB; gpUL55) expressed by a recombinant adenovirus (Ad-gB) was studied in human A549 cells as processing events could affect immunogenicity when such viruses are used as live-recombinant vaccines. Cleavage of [35S]methionine-labelled gp13O into gp93 and gp55 reached a maximum after a 3 h chase. Cleavage was completely inhibited by brefeldin A, suggesting that processing normally occurs as a late Golgi or post-Golgi event. Uncleaved gp 130 remained completely sensitive to endo-beta-N-acetylglucosaminidase H (Endo-H) in untreated cells following long chase periods, indicating high-mannose oligosaccharides at all of the 18 N-linked glycosylation sites (Asn-X-Ser/Thr) and retention in the endoplasmic reticulum. Endo-H analysis of gp55 from swainsonine-treated and untreated cells was consistent with glycosylation at all three potential sites, with two oligosaccharides remaining sensitive to Endo-H and one being processed to Endo-H resistance. The heavily glycosylated N-terminal gp93 subunit was not detected by [35S]methionine-labelling but was easily detected along with gp55 after labelling with [3H]mannose. No cleavage of gp 130 was observed in analogous pulse-chase radiolabelling of Ad-gB-infected human fibroblasts, even though these cells are permissive for HCMV replication and can process the native gB molecule. Processing of gB in recombinant adenovirus-infected A549 cells was generally similar to that previously reported for native gB in HCMV-infected fibroblasts.

Rapid detection of influenza-B virus in respiratory secretions by immunofluorescence during an epidemic

A commercially available indirect immunofluorescent assay for detection of respiratory viruses in nasal secretions was compared with cell culture during an influenza-B epidemic. This assay had poor sensitivity in the detection of influenza-B virus when used directly patients specimens.

Effect of Intranasal Mupirocin Prophylaxis on Methicillin-Resistant Staphylococcus aureus Transmission and Invasive Staphylococcal Infections in a Neonatal Intensive Care Unit

The use of monthly intranasal mupirocin was associated with a significant reduction in the rate of methicillin-resistant Staphylococcus aureus transmission and Staphylococcus aureus invasive infection in a large neonatal intensive care unit. Resistance to mupirocin emerged over time, but it was rare and was not associated with adverse clinical outcomes.Infect Control Hosp Epidemiol 2018;39:741-745.