Lit Review April #2
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
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
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
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
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
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
Point-Counterpoint: Meningitis/Encephalitis Syndromic Testing in the Clinical Laboratory
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
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
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.