Lab Matters Summer 2018 | Page 67

APHL 2018 Annual Meeting Poster Abstracts

among all three beaches . Bacterial load of 0.5 % at Bradford , 0.8 % at McKinley and 0.04 % at South shore beach was observed . However , top five abundant microbial strains ( Hot Spots ) were found in South shore beach , followed by McKinley and Bradford beach . Heatmaps were generated for bacteria , fungi and protist using relative abundance of organisms . Principal Component Analysis based on covariance between bacterial community among each pair of samples demonstrated close clustering between Bradford and McKinley samples indicating greater microbiome similarly between these two areas whereas South Shore samples were clustered away from those . Community resistome profiles demonstrate presence of genes associated with Aminoglycoside resistance in all samples , indicating possible environmental reservoir of Aminoglycoside resistance developed by Gram-negative bacteria .

Conclusion : Metagenomic sequencing approach to explore microbial communities offered critical inside , both on ecological and public health perspectives and underscore the crucial need for more frequent microbiome analysis of waters people encounter on the shoreline .

Presenter : Sanjib Bhattacharyya , PhD , City of Milwaukee Health Department Laboratory , Milwaukee , WI , Phone : 414.286.5702 , Email : sbhatt @ milwaukee . gov

Evaluation of Five Test Methods for Syphilis Screening , Serodiagnosis and Titer Determination in Contra Costa County

L . Sanders , M . Rickard , K . Riddle , C . L . Truong and M . Hung-Fan , Contra Costa Public Health Laboratory , Martinez , CA

Syphilis infection rates are rising in California , especially in high risk populations . Management of patient outcome and infection control requires prompt and accurate identification of early and active syphilis infections . Traditionally , laboratories screen for antibodies common to infection , but not specific to Treponema pallidum ; reactive specimens are tested for T . pallidum-specific antibodies . Seeking increased automation and specificity , new technologies make a case for algorithm reversal : screen for treponemal antibodies and confirm with non-treponemal antibodies . We evaluated traditional and reverse testing algorithms that incorporate the Bio-Rad Laboratories BioPlex 2200 Syphilis Total and Rapid Plasma Reagin ( RPR ) assay , which detects treponemal and nontreponemal antibodies . In our current traditional algorithm , we screen with RPR ; reactive specimens reflex to quantitative Venereal Disease Research Laboratory test ( VDRL ) and Treponema Pallidum Particle Agglutination assay ( TPPA ). We evaluated 359 samples by manual RPR ( Arlington Scientific , Inc .) and BioPlex 2200 Syphilis Total & RPR . Samples reactive by manual RPR reflexed to VDRL ( Becton Dickinson ) and TPPA ( FujirebioSERODIA ). We initially tested 203 samples with each treponemal and non-treponemal assay ( excludingVDRL ). We tested 156 samples with each non-treponemal test ( excluding VDRL ) and the BioPlex SyphilisTotal ; but not TPPA . For the 65 samples reactive with manual RPR , BioPlex RPR , or both , we determined titers with non-treponemal assays ( VDRL , manual RPR and BioPlex RPR ). BioPlex RPR data have positive and negative agreement of 92 % and 95 %, respectively , with our manual RPR data . BioPlex Syphilis Total data have positive and negative agreement of 99 % and 100 %, respectively , with our manual TPPA data . Compared to our current algorithm , the algorithm that screens with the BioPlex RPR has a sensitivity of 92 % and specificity of

95 %. Alternatively , the reverse algorithm screening with the BioPlex Syphilis Total had a sensitivity of 80 % and specificity of 88 %. In the latter approach , specimens reactive by BioPlex Syphilis Total reflexed to RPR and we resolved discrepant results by manual TPPA . Our study demonstrates a need for population-based validation prior to implementing a new infectious disease methodology . In general , selecting a robust testing algorithm that contains a high-sensitivity screening method and a high-specificity confirmatory method will ensure that as many instances of low-level antibodies or antigen are detected , but only those who are truly infected with the disease are treated .

Presenter : Kelly Riddle , Contra Costa Public Health Laboratory , Martinez , CA , Phone : 925.370.5775 , Email : kelly . riddle @ hsd . cccounty . us

Pseudomonas aeruginosa Alters Staphylococcus aureus Sensitivity to Antibiotics

G . Orazi , K . Ruoff and G . O ’ Toole , Geisel School of Medicine , Dartmouth College , Hanover , New Hampshire

Cystic fibrosis ( CF ) patients have impaired mucociliary clearance and thick mucus , which promote respiratory infections . Pseudomonas aeruginosa and Staphylococcus aureus are two of the most prevalent respiratory pathogens in CF infections . Both organisms are associated with poor lung function and patient outcomes . In addition , P . aeruginosa and S . aureus form biofilms in the airway , which cause chronic infections that are recalcitrant to antibiotic treatment . In this study , we found that P . aeruginosa broadly alters the antibiotic sensitivity profile of S . aureus biofilms . P . aeruginosa supernatant can lead to increased tolerance of S . aureus biofilms to certain classes of antibiotics and conversely , can cause increased sensitivity of S . aureus biofilms to other compounds . We observed that P . aeruginosa supernatant significantly increased the antibiotic tolerance of S . aureus biofilms to protein synthesis inhibitors and cell wall-active antibiotics , including vancomycin . The small molecule 2-heptyl-4-hydroxyquinoline N-oxide ( HQNO ) and the siderophores pyoverdine and pyocheline contribute to the ability of P . aeruginosa to protect S . aureus from vancomycin . Additionally , we found that P . aeruginosa supernatant increased the sensitivity of S . aureus biofilms to 60 antibiotics , including chloroxylenol . Treatment of S . aureus with chloroxylenol alone did not decrease biofilm cell viability ; however , the combination of chloroxylenol and P . aeruginosa supernatant significantly reduced S . aureus biofilm viability compared to exposure to chloroxylenol alone . We observed that exogenous HQNO can sensitize S . aureus biofilms to chloroxylenol in a dose-dependent manner . In this study , we have shown that polymicrobial interactions can have dramatic and unexpected impacts on antibiotic sensitivity .

Presenter : Giulia Orazi , Dartmouth College , Geisel School of Medicine , Hanover , New Hampshire , Email : giulia . orazi . gr @ dartmouth . edu

A Multiplexed Chemiluminescent Screening Assay for Determination of IgG Antibodies to Measles , Mumps , Rubella and Varicella Zoster virus ( VZV )

C . Randall , C . Budd , R . Wolfert , J . Harley , E . Harley and R . Budd , Dynex Technologies , Inc ., Chantilly , VA

Infectious Disease