Lab Matters Fall 2024 | Page 56

APHL 2024 POSTER ABSTRACTS

of alternate specimen types to collect when screening for CP-CRA . However , this study suggests that to obtain the most accurate colonization result for CP-CRA , optimally , both rectal and axilla / groin swabs should be collected and tested .

Presenter : Sydney Tracey , sydney . tracey . contractor @ state . mn . us

Correlation Study of Candida albicans Quantification by Automated Cell Counter , qPCR and ddPCR Technologies

M . Veling 1 , P . Xie 2 , L . Chan 2 , M . Pierce 2 , B . Lin 2 , Y . Tong 2 , Revvity Health Sciences 1 , Revvity 2

Candida albians ( C . albicans ), the most common cause of candidiasis , is a top-ranked pathogen in the WHO critical priority group in 2022 . Such fungal infection is invasive and can lead to severe health threats if not properly treated . To facilitate the development of treatment methods , it is crucial to acquire reference material with reliable quantification information for analytical studies . Common quantification methods for C . albicans include counting by cell numbers , optical density , colony forming unit ( CFU ), or by genome material through various methods . As these methods measure different perspectives of the reference material , it is important to understand and select a fit-for-purpose quantification method to address specific biological questions . For example , CFU is unable to measure dead or dying cells that may still retain genomic material necessary for PCR-based analytical studies . In contrast , quantification by genome material requires effective lysis and sample recovery to achieve accurate results when whole intact organism is used . But many yeast organisms , such as C . albicans , are known difficult to be fully lysed in part of their thick cell wall / biofilm structures . Thus , it is hard to compare with counting methods that are based on cell / colony numbers . Here , we proposed a stock concentration correlation study using three different stateof-the-art technologies — fluorescent-based cell counting , real-time quantitative PCR ( qPCR ) and droplet digital PCR ( ddPCR )— to bridge the quantification gap between cell-based and nucleic acid-based methods on tough yeast organism like C . albicans . In this study , we demonstrated that the Cellometer ® X2 system provides reliable quantification of total / live / dead cell count within a few minutes . We also developed an in house short C . albicans lysis procedure that can be used for direct qPCR and ddPCR quantification without the need for sample purification and recovery . As a result , the quantification correlation of C . albicans fresh culture is within threefold differences between the automated Cellometer ® X2 system , qPCR and ddPCR . These data suggest that the Cellometer ® X2 system can be used as a routine , rapid and reliable method for fungi quantification and the newly developed short lysis procedure can be adapted to direct C . albicans qPCR or ddPCR detection without a sample extraction process .

For research use only . Not for use in diagnostic procedures . Presenter : Peishan Xie , Peishan . Xie @ revvity . com

Detection of blaOXA-235 in the AR Lab Network Central Region

R . Bourne , J . Dale , A . Gross , P . Snippes Vagnone , Minnesota Department of Health Public Health Laboratory

Monitoring the spread of antimicrobial resistance ( AR ) through surveillance has been at the forefront of public health efforts .

Surveillance coupled with infection prevention and control initiatives help slow the spread of bacteria harboring AR genes , thereby contributing to the preservation of antimicrobial effectiveness . One of the most concerning causes of AR threats are carbapenemases , enzymes that hydrolyze carbapenems , a class of last resort antimicrobials for multidrug-resistant bacterial infections . The Minnesota Department of Health Public Health Laboratory ( MDH- PHL ) performs real time PCR ( RT-PCR ) testing for carbapenemase genes in carbapenem-resistant Gram-negative organisms . As part of outbreak investigations , whole genome sequencing ( WGS ) is performed on a subset of carbapenemase-producing organisms . During routine WGS analysis of carbapenem-resistant Acinetobacter baumannii ( CRAB ) isolates from Minnesota collected in 2017 , a single isolate was found to harbor a blaOXA-235 gene variant ( blaOXA-237 ). A retrospective assessment of WGS data performed on 236 CRAB isolates collected from 2017-2023 did not identify any additional isolates containing the blaOXA-235 genes besides the initial blaOXA-235 harboring isolate discovered in 2017 . While blaOXA-235 is an emerging carbapenemase gene in the US , MDH had not initiated proactive surveillance for the gene . MDH-PHL currently tests CRAB isolates for genes in the blaOXA gene family , including blaOXA-23 , blaOXA-24 and blaOXA-58 . The discovery of blaOXA-235 underscored the necessity for expanded this testing . Since WGS is not performed on all CRAB isolates , we sought to develop a more efficient and cost-effective method for detecting blaOXA-235 . A RT-PCR assay was developed to specifically detect blaOXA-235 and was used to test CRAB isolates that had not been sequenced and were collected between January and October 2023 at MDH-PHL , the AR Lab Network Central Region Laboratory . A total of 213 isolates were submitted from 7 of 9 states in the AR Lab Network Central Region : MO ( 123 ), OK ( 43 ), IA ( 18 ), AR ( 17 ), MN ( 10 ), ND ( 1 ) and NE ( 1 ). The data revealed that 3 / 213 ( 1.4 %) CRAB isolates harbored the blaOXA-235 gene as determined by RT-PCR . Interesting-ly , all three blaOXA-235 CRAB isolates discovered by the RT-PCR assay and the one isolate dis-covered by WGS originated in Minnesota , each from different healthcare facilities , prompting an ongoing epidemiological investigation . This study highlights the effectiveness of a RT-PCR assay for surveillance of blaOXA-235 in CRAB isolates . In addition , the approach of using RT-PCR prior to WGS is quicker and more cost effective . These results demonstrated the presence of blaOXA-235 in Minnesota and that continued surveillance efforts and testing in the AR Lab Network Central Region are imperative to understand the potential prevalence of this AR gene .

Presenter : Rand Bourne , rbourne @ nevada . unr . edu

Eleven-year review of infant Clostridium botulinum Mouse Bioassay toxin testing at Pennsylvania Department of Health Bureau of Laboratories

L . Dettinger , P . Patel , K . Silas , K . Premkumar , Y . Bandi , D . Xia , Pennsylvania Department of Health Bureau of Laboratories

In the United States ( data from 2014-2019 ), an average of 158 infant cases are reported each year . Infant botulism is a serious paralytic illness caused by a neurotoxin produced by the bacterium Clostridium botulinum . It prevents the release of the neurotransmitter acetylcholine from axon endings at the neuromuscular junction , thus causing flaccid paralysis . This causes a medical emergency and drives the need for the rapid