APHL 2020 POSTER ABSTRACTS
Infectious Disease applied to data . Here , we use our pipeline to look at emerging AMR patterns in Shigella cases in California . As certain resistance genes and plasmids become more common among Shigella , their impact on drug susceptibility must be systematically studied in order to inform public health recommendations on the treatment and prevention of Shigella infections . In this investigation , WGS analysis allows us to discover AMR genes and plasmids in our isolates . We then gain a phenotypic insight into how these features affect drug susceptibility through antimicrobial susceptibility testing ( AST ). Phylogenetic analysis allows us to compare emergent lineages of Shigella with archival isolates to gain a more detailed understanding of evolutionary AMR changes currently underway . Our automated pipeline eases the analysis and visualization of data from this multivariate population study .
Presenter : Lacy Walker , California Department of Public Health , Richmond , CA , laceym . walker1 @ gmail . com
Prevalence of Ciprofloxacin and Azithromycin Resistance in California Shigella species
S . Abromaitis , G . Inami , F . Reyes and Y . Zhao , California Department of Public Health , Richmond , CA
The Centers for Disease Control and Prevention ( CDC ) have declared antibiotic-resistant Shigella a serious threat , and it is estimated that 27,000 drug-resistant Shigella infections occur in the United States each year . According to 2016 CDC National Enteric Disease Surveillance data , most shigellosis cases in California are caused by Shigella sonnei ( 65 %) followed by Shigella flexneri ( 33 %). Infection with Shigella can cause diarrhea , fever and stomach cramps . Symptoms typically resolve within seven days ; however , in some cases treatment with antibiotics may be necessary to decrease illness severity and reduce bacterial shedding . Ciprofloxacin and azithromycin are the primary antibiotics used to treat shigellosis . The California Department of Public Health - Microbial Diseases Laboratory ( CDPH-MDL ) performed Sensititre microbroth dilution testing on 1,137 Shigella isolates received from November 2018 through July 2020 to detect resistance to ciprofloxacin and azithromycin . A total of 566 S . sonnei and 571 S . flexneri were examined . Resistance to ciprofloxacin was evaluated based on the Clinical and Laboratory Standards Institute ( CLSI ) M100 30th Edition ( 2020 ) breakpoint of ≥1 ug / mL . Ciprofloxacin resistance was detected in 65 ( 11 %) of the S . flexneri and 224 ( 40 %) of the S . sonnei tested . Azithromycin epidemiological cut off ( ECV ) values for S . flexneri and S . sonnei of ≥16 and ≥32 ug / mL respectively were used to determine non-wild-type strains based on guidelines from the CLSI M100 30th Edition ( 2020 ). Azithromycin non-wild-type was detected in 300 ( 53 %) of the S . flexneri and 209 ( 37 %) of S . sonnei tested . Dual resistance to azithromycin and ciprofloxacin was detected in 191 ( 17 %) of the Shigella isolates . Rates of resistance observed in California are higher than those reported in national surveillance and were found in isolates throughout the state .
In 2017 , the CDC reported an increase in Shigella isolates with decreased susceptibility to ciprofloxacin ( DSC ), defined as having a minimum inhibitory concentration ( MIC ) range of 0.12-1.0 ug / mL . DSC Shigella are of concern because even though they were not considered resistant by the 2017 CLSI guidance , they often encode a quinolone resistance gene . It has been suggested that treatment of DSC with ciprofloxacin could lead to further reduction in ciprofloxacin sensitivity and treatment failure . In this study , 102
( 18 %) S . flexneri and 203 ( 36 %) S . sonnei had MIC within the DSC range . The high proportion of both resistant and DSC isolates found by CDPH-MDL highlights the growing problem of drug-resistant Shigella .
Presenter : Stephanie Abromaitis , California Department of Public Health , Microbial Diseases Laboratory , Richmond , CA , stephanie . abromaitis @ cdph . ca . gov
Antimicrobial Susceptibility of Carbapenem-resistant Pseudomonas aeruginosa Isolates Tested at CDC , 2018 – 2019
A . Bhatnagar 1 , 2 , J . Huang 2 , D . Campbell 2 , N . Reese 2 , R . Balbuena 1 , 2 , S . Boyd 2 , J . Cochran 1 , 2 , C . Longo 1 , 2 , S . Swint 2 , K . F . Anderson 2 , D . Lonsway 2 , S . Vallabhaneni 2 , S . Malik 2 , J . Grass 2 , M . Walters 2 , J . Lutgring 2 , M . Karlsson 2 , A . Brown 2 ; 1 Centers for Disease Control and Prevention , Atlanta , GA , 2 Goldbelt C 6 LLC , Juneau , AK
Introduction : The emergence of carbapenem-resistant Pseudomonas aeruginosa ( CRPA ) is a major public health threat as treatment options are limited . Carbapenemase-producing CRPA is particularly concerning as resistance genes are sometimes carried on mobile genetic elements . We describe the antimicrobial susceptibility of CRPA isolates tested at the Centers for Disease Control and Prevention ( CDC ).
Methods : We analyzed suspect carbapenemase-producing CRPA submitted by the Antibiotic Resistance Laboratory Network ( AR Lab Network ) and a sample of CRPA from the Emerging Infections Program ( EIP )’ s laboratory- and population-based surveillance sent to CDC between 1 / 1 / 2018 and 10 / 31 / 2019 . Antimicrobial susceptibility testing was performed by reference broth microdilution against 15 drugs according to Clinical and Laboratory Standards Institute ( CLSI ) guidelines . Interpretive criteria were applied using CLSI ’ s M100 29th ed . We confirmed carbapenemase production in all isolates using the modified carbapenem inactivation method ( mCIM ). Real-time PCR was performed for up to four carbapenemase genes : blaKPC , blaNDM , blaIMP and blaVIM . Isolates were categorized as carbapenemase gene-positive ( CP-CRPA ), mCIM positive / PCR negative ( mCIM +/ PCR- ), mCIM indeterminate / PCR negative ( mCIM IND ), mCIM negative ( non-CP ). Multidrug-resistant ( MDR ) and extensively drug-resistant ( XDR ) were defined using standard definitions .
Results : Of 903 confirmed CRPA ( resistant to imipenem , meropenem or doripenem ), 575 ( 63.7 %) were non-CP , 223 ( 24.7 %) were CP-CRPA ( 76 blaVIM , 74 blaKPC , 34 blaIMP , 29 blaNDM , 10 with two carbapenemase genes ), 94 ( 10.4 %) were mCIM +/ PCR- , and 11 ( 1.2 %) were mCIM IND . EIP contributed 509 ( 88.5 %) of the non-CP , 5 ( 2.2 %) of the CP-CRPA , 7 ( 7.4 %) of the mCIM +/ PCR- , and 0 mCIM IND isolates . Among non-CP and CP-CRPA , 77 % and 99.6 % were MDR , respectively ; 47.7 % and 94.6 % were XDR , respectively . Susceptibility to ceftolozane-tazobactam was 90.1 % among non-CP CRPA but was not observed among CP-CRPA . The respective percent susceptible for non-CP versus CP-CRPA was 55.3 % and 1.8 % for ceftazidime , 51.7 % and 4.9 % for cefepime , and 85 % and 24.2 % for ceftazidime-avibactam .
Conclusion : Carbapenemase-producing P . aeruginosa tested at CDC displayed a high frequency of the XDR phenotype . In 2019 , CDC shared guidance to help public health laboratories identify CP-CRPA more efficiently by focusing mechanism testing on isolates that are nonsusceptible to ceftazidime or cefepime . This study ’ s findings further suggest that nonsusceptibility to ceftolozane-tazobactam