Utility of terminal hemadsorption for detection of hemadsorbing respiratory viruses from conventional shell vial cultures for laboratories using R-Mix cultures.

BACKGROUND: Many laboratories using R-Mix cell lines inoculate other shell vial cultures to improve the recovery of viruses, and in particular, perform terminal hemadsorption (THad) following 10-14 days of incubation to improve detection of respiratory viruses. We explored the cost-effectiveness and added benefits of THad on conventional shell vial cultures from respiratory samples for laboratories using R-Mix cell lines. OBJECTIVES: To determine if eliminating the practice of THad from conventional shell vial culture when R-Mix cultures are negative, would result in a significant reduction in the number of hemadsorbing respiratory viruses detected. STUDY DESIGN: THad results were retrospectively reviewed for 41,129 respiratory shell vial cultures that were set up concurrently with R-Mix cultures. RESULTS: Greater than 95% of hemadsorbing respiratory viruses were recovered by R-Mix standard protocol within 24h of inoculation, and only 5% were detected by THad at 10-14 days. CONCLUSION: The practice of hemadsorption at days 10-14 for conventional shell vial cultures from respiratory specimens should be discontinued for laboratories using R-Mix due to its low yield, questionable clinical impact of delayed results and additional costs.

Comparison of multiple shell vial cell lines for isolation of enteroviruses: a national perspective.

BACKGROUND: Isolation of enterovirus in cell culture is still utilized by clinical laboratories, for vaccine research, and for identifying serotypes for disease surveillance. Use of a combination of cell lines is recommended yet this practice has not been rigorously examined for shell vials. OBJECTIVES: To evaluate the growth predilection of enterovirus serotypes for certain shell vial cell lines in clinical samples received at a national reference laboratory. STUDY DESIGN: We retrospectively reviewed results of samples submitted for viral culture over a 3-year period. PMK, BGM, RD, A549, and MRC-5 cell lines grown in shell vials were inoculated and serotyped. RESULTS: Of 55,816 cultures, 1047 (1.9%) yielded enterovirus representing 18 serotypes. Echovirus 7, echovirus 9, and echovirus 30 were the most common serotypes recovered in 2002, 2003, and 2004, respectively. PMK and MRC-5 recovered the majority of enterovirus isolates; the addition of BGM and RD cells increased our recovery rate by 13%. For 52.6% of enteroviral isolates, cytopathic effect was found in only a single cell line. PMK and BGM cells were effective in isolating coxsackieviruses, and RD and MRC-5 were useful particularly in isolating echoviruses. CONCLUSIONS: A combination of shell vial cell lines is still recommended for recovery of enteroviruses.

Evaluation of three Copan viral transport systems for the recovery of cultivatable, clinical virus isolates.

Three Copan viral transport media (VTM) were compared to the BBL Viral Culturette and Micro Test M4 systems for their ability to maintain the viability of clinical strains of enterovirus, herpes simplex virus, adenovirus and parainfluenza virus. VTM were inoculated, incubated up to 72 h at both 4 degrees C and 22 degrees C, and processed for cell culture. The concentration of infectious virus in VTM was determined by standard endpoint dilution assay. All VTM maintained viable enterovirus and adenovirus for 72 h but adenovirus from M4 and Copan CVM media were detected in cell culture at least one day sooner than from other media. Only M4 and Copan CVM media supported the recognition of low-titer herpes simplex virus in cell culture within 24 h. Parainfluenza virus was consistently detected in culture within six days when maintained in M4 and two of the Copan VTM media. Overall, the Copan CVM compared favorably to the M4 in maintaining concentrations of viable virus that could be recovered and identified rapidly in routine cell culture.

Limited applicability of direct fluorescent-antibody testing for Bordetella sp. and Legionella sp. specimens for the clinical microbiology laboratory.

The rapid diagnosis of infections with Bordetella and Legionella species is important for patient management. With observed increases in direct fluorescent-antibody (DFA) testing volumes, we retrospectively compared the performance characteristics of DFA testing to those of culture and PCR. For Bordetella sp., samples were classified as positive by DFA testing (184 [3%] of 6,195 samples) and culture (150 [2%] of 6,251 samples) significantly less often than by PCR (2,557 [10%] of 26,929 samples). Of 360 samples tested by both DFA and PCR methods, 81 (16 by DFA testing and 79 by PCR) were determined to be positive for Bordetella, with a sensitivity and specificity of DFA testing of 18% and 99%, respectively. Of 1,426 samples tested by both DFA and culture methods, 48 (44 by DFA testing and 15 by culture) were determined to be positive for Bordetella, with a sensitivity and specificity of DFA testing of 73% and 98%, respectively. For Legionella sp., samples were identified as positive by DFA testing (31 [0.25%] of 12,597 samples) and culture (85 [0.6%] of 13,572 samples) significantly less often than by PCR (27 [4%] of 716 samples). Of 62 samples tested by both DFA and PCR methods, none were positive for Legionella sp. by DFA testing and 3 were positive by PCR. Of 3,923 samples tested by both DFA and culture methods, 22 (3 by DFA testing and 21 by culture) were positive for Legionella sp., with a sensitivity and specificity of DFA testing of 9.5% and 100%. Overall, DFA testing for Bordetella sp. and Legionella sp. is an insensitive method, and despite its continued popularity, clinical microbiology laboratories should not offer it when more sensitive tests like PCR are available.