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Lit Review April #2

April 14, 2018

Disclaimer: this compilation of synopses have been collected from multiple sources, including Mark Crislip's Puscast, Journal Watch Infectious Diseases, Medscape Infectious Diseases, CDC MMWR, AMA Morning Rounds, ProMED Mail, Journal of Clinical Microbiology, Antimicrobial Agents and Chemotherapy, Clinical Infectious Diseases, and more. I chose these articles based on their relevance to clinical microbiology and would be of interest to my fellows, and some other pieces that I found amusing to read. All credit goes to these original contributors. I'm just a messenger :).

 

Leading Photo by Jakub Kapusnak

Virus in Semen and the Risk of Sexual Transmission

http://www.nejm.org/doi/10.1056/NEJMe1803212

  • We usually just think about sexually transmitted viruses, but non-ST could also be found commonly

  • Zika virus (ZIKV), Ebola virus (EBOV): found in semen from symptomatically infected patients and disease survivors

  • Most reports use molecular detection and not looking at infectivity

  • This study: only 4% of ZIKV RNA–positive semen was infectious

    • Infectivity only in samples obtained within 30 days after onset

    • These samples had viral load of more than 10^7 RNA copies/mL

    • This short period may allow for sexual transmission

  • EBOV: no clear data to confirm sexual transmission, although RNA could be present in semen after 1 year

  • Maybe should be diagnosed using viral culture, but tons of work

  • Guidelines for sexual practices in patients exist, but may need to be updated when new data come out

From Journal Watch: 2018 U.S. Adult Immunization Schedule

  • What’s new?

    • Recombinant VZV vaccine (RZV) is now preferred is most cases

      • Immunocompetent people > 50 should get RZV regardless of previous history of VZV infection

      • People who already received live-attenuated should also get RZV, but should be at least 2 months apart

      • Recommended in most underlying conditions EXCEPT severely IC or pregnant because there is no data

    • Due to mumps outbreak: people who received ≤2 MMR shots should get an extra shot of mumps-containing vaccine

    • Tables below from the CDC

 

 

 

 

Multicenter, randomized controlled, observer‐blinded study of a nitric oxide generating treatment in foot ulcers of patients with diabetes – ProNOx1 study

https://onlinelibrary.wiley.com/doi/abs/10.1111/wrr.12630

  • These wounds are not easy to treat, generally dressing is very important (more important than antimicrobial therapy) but not a lot of data

    • NO: helps maintaining microvascular supply, induce immune system and has a broad spectrum antimicrobial property 

    • Absence of NO in diabetes associated with poor ulcer healing

  • New study showing safety and efficacy of EDX110, a nitric oxide generating medical device

    • Provides moist wound environment

    • Absorbs exudate and triggers autolytic debridement

    • Generate NO in situ when two layers make contact

    • Has been tested per FDA to claim antimicrobial property

      • S. aureus, S. epidermidis, B. subtilis, K. pneumoniae, P. aeruginosa, E. coli

      • C. albicans, Geotrichum candidum

    • Shown to prevent biofilms formation

 

 

 

  • Looked at > 130 patients

  • At 12 wk, 88.6% area reduction compared to 46.9% for SOC

Four-gene Pan-African Blood Signature Predicts Progression to Tuberculosis

https://www.atsjournals.org/doi/abs/10.1164/rccm.201711-2340OC

  • People have been trying to use RNA profiling of blood cells as biomarkers for progression of TB infection

  • This group previously identified expression of 16 genes that could predict progression in  M.tb-infected HIV-negative South African and Gambian adolescents and household contacts

    • These genes identified from small dataset, and may not be application to pan-African population

  • Looked at 4,466 HIV-negative healthy HHC of 1,098 index TB cases between 2006 and 2010

  • Used RNA sequencing, PCR, and Pair Ratio algorithm in a training/test set approach

  • Identified 4-transcript signature panel with differential expression in progressors vs matched controls

    • Predicted TB progression up to 2 years before clinical symptoms

    • Upregulated: GAS6, SEPT4

    • Downregulated: CD1C, BLK

    • Converted to PCR detection and pared down to only SEPT4 and BLK and still performed well in pan-African datasets

Uropathogens and Pyuria in Children With Neurogenic Bladders

 

http://pediatrics.aappublications.org/content/early/2018/04/06/peds.2017-3006

  • Some kids with neurogenic bladder need intermittent cath, and often have pyuria

    • What bugs are associated with presence or absence of pyuria

  • Study looked at > 2400 cultures and associated UA results in patient 18 yo and younger

    • Enterococcus associated with absence of pyuria and neg leu esterase

    • P. mirabilis associated with presence of pyuria and pos esterase

    • P. aeruginosa associated with pos esterase only

  • Moral of the story: kids with neurogenic bladder will need a urine culture regardless of UA results

Clinical presentation of Cardiac implantable electronic devices (CIED) infection following initial implant versus reoperation for generator change or lead addition

 

http://openheart.bmj.com/content/5/1/e000681

  • These infection are disproportionately increasing

  • Infections can occur after initial implantation or after generator change

    • Previous studies showed that there was greater risk after generator change compared to initial implantation, possibly due to pocket colonization

    • Need a closer look at cases

  • Looked at >400 patients

    • Patients with post-initial implant infections, although less likely to get infected, presented earlier post-procedure compared to later operations

    • Post-initial infections associated with more S. aureus, and resulted in more severe infection with higher risk for new valvular regurgitation and metastatic infections

    • Post-generator change infections associated more with CoNS

Total Laboratory Automation in Clinical Microbiology: a Micro-Comic Strip

http://jcm.asm.org/content/56/4/e00176-18.full

 

 

Point-Counterpoint: Meningitis/Encephalitis Syndromic Testing in the Clinical Laboratory

 

http://jcm.asm.org/content/56/4/e00018-18.abstract

  • Some good evidence demonstrated false positive and false negatives

  • People argue for and against use of the panel, and if offered, should there be restrictions?

  • FOR: these tests could be a game changer

    • Failure to identify etiologic agents in lots of cases

    • Negate the initial requirement for a priori knowledge of potential agents

    • Could be helpful in viral infections, especially agents that are more esoteric (HHV-6, CMV, and HPeV)

    • When used in conjunction with clinical evaluation, allows for timely diagnosis (decrease TAT compared to sendouts) and proper management, especially in culture-negative cases

  • AGAINST: identification of true cause of ME is a rare occurrence

    • Generally, syndromic panel testing is good when used in right patients, but clinical presentations of ME vary greatly

    • Some evidence showed that PCR-positive but conventional-negative cases are more likely to be false positive

    • More sensitive doesn’t mean better test

    • Real world data are not quite as awesome as the primary clinical study

    • Is there a lot of utility in some viral targets?

      • Lots of healthy people have HHV-6 in their brains

      • Positive CMV: actual ME or latent infection in white cells?

    • Bacterial targets: would one not give antibiotics if negative PCR? Culture still needed.

The Slow March toward Rapid Phenotypic Antimicrobial Susceptibility Testing: Are We There Yet

 

http://jcm.asm.org/content/56/4/e01999-17.full

  • People have been trying to find ways to shorten TAT for phenotypic AST

    • Direct from positive blood culture

      • DD or use as inoculum for automated systems (Vitek 2)

    • Detection of resistance gene: lack the ability to fully capture full resistance profiles

  • Growth based AST has limitations

    • Conventional: limited by lag phase – organism has to be actively growing

    • Requires standardized inoculum, which is usually higher that in actual specimen

  • Nanoscale technology with microfluidics

    • Allows for replicates within single assay

    • Measures OD, fluorescence secondary to metabolic pathways

  • AXDX Pheno: FDA approved

    • FISH with microscopy-based, single-cell analysis to assess growth and susceptibility

    • ID in 1.5 hr, AST in about 7 hours

  • Sounds awesome, but would it be picked up?

    • Could make workflow more cumbersome

    • Studies suggested that treatment in septic patients are usually decided at time or draw or gram stain and faster results may have little impact

  • In which cases would this be definitely helpful?

    • De-escalation or escalation in the setting of endemic resistance

    • Use in conjunction with stewardship

  • Success depends on local prevalence of resistance and the manner in which the system is integrated into practice

Multistate Outbreak of E. coli O157:H7 Infections Linked to Chopped Romaine Lettuce

 

https://www.cdc.gov/ecoli/2018/o157h7-04-18/index.html

  • 35 people infected with outbreak strain of E. coli O157:H7 have been reported from 11 states

  • Not related to leafy green outbreak earlier this year

  • Most people reported eating chopped lettuce at a restaurant in March

    • All used bagged chopped lettuce

  • Chopped romaine lettuce from the Yuma, AZ

  • No grower, supplier, distributor source or brand has been identified

  • Recommendation: all store-bought chopped romaine lettuce including salads and salad mixes containing chopped romaine lettuce should be thrown away

     

     

     

     

     

     

     

     

     

  • That's all for now. Bug Hunters, may the odds be ever in your favor. 

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PEERA HEMARAJATA, M.D., PH.D., D(ABMM)

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