Ella M. Swierkosz

Impetigo contagiosa. III: Comparative efficacy of oral erythromycin and topical mupirocin

Abstract: Ninety‐seven patients with impetigo were prospectlvely enrolled in a study to determine the comparative efficacy of systemic and topical antibiotic therapy. After obtaining a bacterial culture from a representative losion, the children were randomized to receive seven days of either oral erythromycin or topical mupirocin administered three times daiiy. Staphylococcus aureus aione was Isoiated from 51% and in association with group A β‐hemoiytic streptococci (GABS) from 29%; GABS aione was isoiated from 4% of patients. Of 48 children who received erythromycln, 43 (90%) were citnicaily improved or cured, and 11 of 17 were bacteriologicaliy cured. Of 49 children who received mupirocin, 47 (96%) were clinicaily improved or cured, and 10 of 14 were bacterioiogicaiiy cured. At three week foliow‐up, clinical cure rates and number of secondary househoid cases of impetigo were equivaient In both treatment groups. Mupirocin appears to be a weil‐toierated, aibeit expensive, aiternative to erythromycin for the treatment of impetigo.

Multicenter Study of Clinical Performance of the 3M Rapid Detection RSV Test

ABSTRACT This multicenter study evaluated the clinical performance of the 3M Rapid Detection RSV test (3MRSV) compared to a composite reference standard of R-Mix culture and direct specimen immunofluorescence for detection of respiratory syncytial virus (RSV). The performance of the BinaxNOW RSV test was also evaluated using this reference standard. In a secondary analysis, discordant results were arbitrated using the Gen-Probe/Prodesse ProFlu+ reverse transcription-PCR (RT-PCR) assay. Subjects were stratified into three groups as follows: group 1 (G1), all ages; G2, subjects <22 years old (FDA-cleared ages for 3MRSV testing); and G3, subjects <5 years old (FDA-cleared ages for BinaxNOW RSV testing). A total of 1,306 specimens (G1, n = 1,306; G2, n = 1,140; G3, n = 953) from subjects of all ages presenting with respiratory symptoms met study criteria for analysis. Sensitivities, specificities, positive predictive values, and negative predictive values of 3MRSV for G1 were 86.5%, 95.8%, 91.4%, and 93.2%, respectively, and those for G2 were 87.3%, 95.6%, 92.4%, and 92.5%, respectively. For those samples analyzed by both 3MRSV and BinaxNOW, the 3MRSV was more sensitive (G1, 86.3%; G2, 87.2%; and G3, 89.9%) than was BinaxNOW (G1, 70.84%; G2, 72.0%; and G3, 72.4%) (P < 0.05). Specificities for RSV detection from nasopharyngeal (NP) aspirates and NP swabs for all groups were comparable for 3MRSV and BinaxNOW, but 3MRSV was less specific than BinaxNOW when nasal washes/aspirates were tested (P < 0.05). The 3MRSV assay performed well for the detection of RSV, and the overall assay performance was superior to that of BinaxNOW. The 3MRSV reader eliminated user misinterpretation and provided test result and quality control documentation.

Strategy for efficient detection of respiratory viruses in pediatric clinical specimens

Direct immunofluorescence (IF) with a polyclonal respiratory syncytial virus (RSV)-specific antibody preparation was used for antigen detection during the 1982-1983 RSV season (155 specimens) and gave an overall sensitivity of 94% with 87% specificity compared with viral culture. Indirect IF was used in the 1983-1984 season (265 specimens) and exhibited sensitivity of 96% with specificity of 79%. During these two seasons, 42 of 224 (18.8%) specimens that were IF-negative for RSV grew viruses other than RSV. In the winter of 1984-1985, we screened 297 specimens for RSV by IF and 80 (27%) were positive. Forty-four (20%) of the IF-negative specimens were culture-positive for RSV(2) or other viruses(44). We conclude that, in the interest of cost reduction and expeditious detection of respiratory viruses, once a properly equipped laboratory has become thoroughly familiar with IF techniques, pediatric respiratory specimens can be screened for RSV by IF and only the IF-negative specimens need be inoculated into cell cultures for isolation of virus during the winter respiratory season.

Effects of sonication and centrifugation of clinical specimens on the recovery of herpes simplex virus

We have analyzed frozen and fresh specimens for herpes simplex virus (HSV) to determine the effect of sonication and centrifugation on virus recovery. After sonication, titers of 24/27 specimens increased from 1.3-30.8-fold with a mean increase of 6.8-fold. One hundred seventy-four fresh specimens were inoculated before and after sonication into CV-1 tube cultures. There was not a statistically significant difference in time to positivity between the sonicated and unsonicated portions. Thus, although sonication of specimens can sharply increase the viral titer of positive specimens, sonication of fresh specimens does not significantly enhance the isolation of HSV. To determine the effect of centrifugation of clinical specimens on recovery of HSV, thirty-one culture positive frozen specimens were centrifuged, and the supernatants and resuspended sonicated pellets were titered. Twenty-five specimens had sufficient recoverable virus to titer; in 21/25 (87.5%) specimens the titers were reduced in the supernatants after centrifugation (mean reduction 38%; range of 4-92%). Two of 31 (7%) supernatants were negative in culture while the sonicated pellets were positive. Thus, centrifugation of specimens prior to cell inoculation may compromise recovery of HSV.

Serologic confirmation and typing of clinical herpes simplex virus isolates: comparison of two different monoclonal antibody immunofluorescence kits

Abstract Two direct innunofluorescence assays using murine monoclonal antibody reagents (Microtrak ™ , Syva Co.; Pathfinder ™ , Kallestad Laboratories, Inc.), were evaluated for culture confirmation and typing of clinical herpes simplex virus (HSV) isolates. Of 101 HSV isolates initially tested with both sets of reagents, 82 of 101 isolates were confirmed and typed as HSV-I and 19 were typed as HSV-II with the Microtrak ™ reagents. The Pathfinder ™ reagents confirmed and typed 70 of 101 HSV isolates as HSV-I and the same 19 as HSV-II. Twelve isolates could not be confirmed or typed with the Pathfinder ™ reagents. Restriction endonuclease analysis showed these 12 HSV isolates to be HSV-I. Subsequently, a new HSV-I monoclonal antibody was added to the original HSV-I Pathfinder ™ reagent for re-evaluation. The 12 discrepant isolates and 118 new HSV isolates were tested both with the original Microtrak ™ reagents and with the original HSV-II and the new HSV-I Pathfinder ™ reagents. One hundred isolates were confirmed and typed as HSV-I and 30 as HSV-II by both sets of reagents. These evaluations emphasize the continual need for quality control within the clinical laboratory to insure that commercially available reagents indeed perform as expected.

Multicenter Evaluation of the ePlex® Respiratory Pathogen Panel for the Detection of Viral and Bacterial Respiratory Tract Pathogens in Nasopharyngeal Swabs

ABSTRACT The performance of the new ePlex Respiratory Pathogen (RP) panel (GenMark Diagnostics) for the simultaneous detection of 19 viruses (influenza A virus; influenza A H1 virus; influenza A 2009 H1 virus; influenza A H3 virus; influenza B virus; adenovirus; coronaviruses [HKU1, OC43, NL63, and 229E]; human rhinovirus/enterovirus; human metapneumovirus; parainfluenza viruses 1, 2, 3, and 4; and respiratory syncytial virus [RSV] [RSV subtype A and RSV subtype B]) and 2 bacteria (Mycoplasma pneumoniae and Chlamydia pneumoniae) was evaluated. Prospectively and retrospectively collected nasopharyngeal swab (NPS) specimens (n = 2,908) were evaluated by using the ePlex RP panel, with the bioMérieux/BioFire FilmArray Respiratory Panel (BioFire RP) as the comparator method. Discordance analysis was performed by using target-specific PCRs and bidirectional sequencing. The reproducibility of the assay was evaluated by using reproducibility panels comprised of 6 pathogens. The overall agreement between the ePlex RP and BioFire RP results was >95% for all targets. Positive percent agreement with the BioFire RP result for viruses ranged from 85.1% (95% confidence interval [CI], 80.2% to 88.9%) to 95.1% (95% CI, 89.0% to 97.9%), while negative percent agreement values ranged from 99.5% (95% CI, 99.1% to 99.7%) to 99.8% (95% CI, 99.5% to 99.9%). Additional testing of discordant targets (12%; 349/2,908) confirmed the results of ePlex RP for 38% (131/349) of samples tested. Reproducibility was 100% for all targets tested, with the exception of adenovirus, for which reproducibilities were 91.6% at low virus concentrations and 100% at moderate virus concentrations. The ePlex RP panel offers a new, rapid, and sensitive “sample-to-answer” multiplex panel for the detection of the most common viral and bacterial respiratory pathogens.

Nosocomial viral infections revisited

In 1980 and 1981, Valenti et al. (l-4) published a series of ground-breaking articles that addressed, for the first time in a comprehensive manner, the epidemiology and control of nosocomial viral infections. Since then, significant advances have been made in viral diagnosis, prophylaxis, and treatment of viral infections. Moreover, these guidelines were published before the recognition of human immunodeficiency virus (HIV) and hepatitis C virus (HCV) and before the implementation of “standard” precautions in the health care setting. The following, then, is an overview and an update on the detection and prevention of nosocomial viral infections. Nosocomial viral infections can be separated into different categories based on their mode of transmission. Bloodborne viruses, such as cytomegalovirus (CMV), hepatitis B virus (HBV), HCV, hepatitis D virus, HIV1 and -2, parvovirus, HTLV-I, and HTLV-II, are transmitted by transfusion and blood and blood products. In addition, undergoing dialysis or organ-transplantation and contact with certain body fluids have also been shown as routes of transmission for some of these viruses (5). Airborne transmission by smallparticle aerosol nuclei ( Gum in size) has been implicated for influenza, measles, and varicella-zoster (VZV) viruses. Large-droplet (>5pm) aerosol transmission occurs with adenovirus, influenza virus, mumps virus, parainfluenza virus, parvovirus B 19, rhinovirus, respiratory syncytial virus, and rubella virus. Enteric adenoviruses, enteroviruses, hepatitis A virus (HAV), rotavirus, and other gastroenteritis viruses are transmitted by the fecal-oral route or by contact with contaminated objects or surfaces in the patient’s environment. Herpes simplex virus (HSV) and VZV are spread by direct contact with patient lesions; CMV and HSV are spread by intimate contact with infectious secretions (2,6,7).

The Use of the Polymerase Chain Reaction in Influenza Virus Detection and Characterization

We have shown that the sequence of the hemagglutinin gene of influenza virus can be determined from virus recovered from nasopharyngeal swabs collected for diagnostic purposes by using the polymerase chain reaction (PCR) to amplify cDNA made by reverse transcriptase (Rajakumar et al. 1990). These studies suggest that PCR might be used in the routine diagnosis of influenza. Our experience indicates that the success of such a procedure would depend on (1) obtaining adequate cDNA synthesis from all virus strains encountered in clinical samples, (2) eliminating problems of DNA contamination, (3) ensuring production of amplified DNA from the appropriate influenza virus genes, and (4) developing appropriate methods to identify virus strains. The feasibility of such an approach to diagnosis is discussed with respect to sensitivity, reliabil ity, virus strain identification, speed, and cost.

VIRALLY INDUCED MEMBRANE PERMEABILITY CHANGES AS A POSSIBLE LINK BETWEEN INFLUENZA B AND REYE'S SYNDROME

The mechanism by which viral infection can lead to the multiple metabolic derangements characteristic of Reyes Syndrome is not understood. The possibility that influenza virus could induce changes in membrane permeability to nutrients ordinarily concentrated within the cell was examined. Madin Darbin canine kidney (MDCK) cells were infected by egg grown influenza B virus by two routes: at physiological conditions, pH 7.4, 37°C; and adsorption at 0°C followed by brief exposure to pH 5.0, 37°C. Control cells were mock-infected with allantoic fluid. Transport (uptake and release) of phosphate (Pi) 2-deoxyglucose (dGlc) and α-aminoisobutyric acid (AIB) were measured at various intervals 0 to 10 hours after infection. At physiological pH, Pi uptake by infected cells was inhibited (p< 0.01) at 0 to 2 hours as compared to controls. Uptake of AIB was also inhibited (p< 0.01) at 0 to 2 hours. The uptake of all nutrients was higher at 6 to 10 hours in infected cells as compared to controls (p< 0.01). When release of Pi and dGlc was measured, there was no difference between infected cells and controls at 0-10 hours. At low pH, fusion occurred in infected cells, but not in control cells. Fused infected cells demonstrated both significantly increased release and diminished uptake of nutrients compared to controls. Thus influenza B virus can induce changes in host cell membrane permeability that may have important implications for cell metabolism.