Category: Infectious Disease

It’s Not An Abscess (Yes It Is)

These studies pretty much all end up saying the same thing – academic faculty can’t agree on the presence or absence of differentiating characteristics between abscess and cellulitis.  This particular study is in a pediatric population, and, there’s a lot of kappa and absolute agreement to comb through in their tables, but, basically, about 20% of the time two attendings substantially disagreed.  The authors then follow this up by observing that an I&D was performed 75% time, and purulent material was found 92% of the time.

The best conclusion from this might be – if there’s some ambiguity, put a scalpel in it.  I’d say this is reasonable – because we’ve seen a hundred times the child who bounces into the ED on day 3 of cephalexin for cellulitis because what he really had was a MRSA abscess to begin with.

Or, if you have an ultrasound with a high-frequency probe, you might be able to differentiate homogenous hyperemia from fluid collection.

“Interexaminer Agreement in Physical Examination for Children With Suspected Soft Tissue Abscesses”
www.ncbi.nlm.nih.gov/pubmed/21629150

The Diagnose-a-Tron of the Future: FDG-PET

Imagine, if necessary, a case you see every hour in the ED – a child with a fever.  Wave a magic wand in triage, find the source of the fever, and let the doctor pick up the decision-making process advance from there.

This scenario is, of course, totally farfetched – after all, you still need a certain number of HPI and ROS elements before you wave the magic wand to bill at a higher level of service.

But, the principle – this is a fascinating article regarding the workup of “fever of unknown origin” in adults.  These 81 patients had fevers for 3 weeks without a satisfactory explanation, and their cases were retrospectively reviewed following referral to FDG-PET scans.  Essentially, any time this FDG-PET scan localized to an area of high uptake, it provided significant helpful localizing information regarding the underlying disease process.  Examples of diagnoses it identified were infectious endocarditis, tuberculosis, pyogenic spondylitis, graft infections, Takayasu arteritis, and a host of other fascinatingly difficult diseases to identify.

The main diagnostic drawback is that it is mostly only structurally/anatomically specific, not necessarily disease specific, so there is a lot to do in terms of clinical correlation with imaging findings.  And then there is the small issue where it’s a nuclear medicine study requiring 5 hours of fasting and an injection of the FDG tracer 1 hour before the study is performed.  But, someday a decade out, the next generations of these devices might be more clinician-friendly….

“FDG-PET for the diagnosis of fever of unknown origin: a Japanese multi-center study.”
www.ncbi.nlm.nih.gov/pubmed/21344168

Babesiosis – Scourge of the Lower Hudson Valley

Fascinatingly, babesiosis has suddenly become endemic to New York.  From 6 cases per year between 2001-08, it’s now up to 100+ cases per year in the region.  Still nothing compared to the 4600 cases of Lyme disease, but nearly rivaling the 213 cases of ehrlichiosis.

Hospitalized patients had fever and hemolytic anemia, and were treated with azithromycin and atovaquone.  5.6% case-fatality rate, although, the parasitemia in these cases was exacerbated by underlying medical conditions.  Won’t see this down here in Texas, but the public health surveillance responsibility of Emergency Medicine is always important to remember.

“Babesiosis in Lower Hudson Valley, New York, USA.”
www.cdc.gov/eid/content/17/5/pdfs/10-1334.pdf

Algorithmic Approach To Detect Sepsis Fails

I was asked to blog about this little article – since it lies at the intersection of Emergency Medicine and informatics.

So, that feeling you get when you look at a patient who is obviously ill?  Computers don’t have that yet.  These folks tried to encapsulate that feeling of “sick” vs. “not sick” into the criteria for severe sepsis, which includes SIRS and hypotension.  The hope was that an algorithmic approach that automatically recognized the vital sign and physiologic criteria for SIRS would trigger reminders to clinicians that would spark them to initiate certain quality care processes sooner.
Out of 33,460 patients processed by the system, 398 triggered the system.  Less than half (46%) of those were true positives.  To follow that up, they tried to evaluate their system for sensitivity and specificity by pulling 1 week’s worth of data (1,386 patients) for closer review – and they found the system generated 6 false positives, 7 true positives, and 4 false negatives.  And those numbers speak for themselves.
Looking back at their four quality measures, they all showed a trend towards improvement – unfortunately three of their four quality measures don’t even have a theoretical connection to improved outcomes.  Chest x-ray, blood cultures, and measuring a serum lactate are all clinically relevant in certain situations, but they are all diagnostic and management decisions independent of “quality”.  Antibiotic administration, however, is part of EGDT for sepsis (for what it’s worth), and that trended towards improvement (OR 2.8, CI 0.9 to 8.6).  
But the final killer?  “In approximately half of patients electronically detected, patients had been detected by caregivers earlier”.  So, clinicians were receiving automated pages suggesting they might consider an infectious cause to hypotension, probably while already placing central lines for septic shock.
Great concept – but automated systems just don’t yet have robust, rapid, high-quality inputs like those a clinician gets just by walking in the room.  But, EM physicians in busy departments overlook things – and a well-designed system might in the future help catch some of those misses.
“Prospective Trial of Real-Time Electronic Surveillance to Expedite Early Care of Severe Sepsis.”

Pediatric Sexual History Should Not Be Neglected

I am torn regarding whether 82% represents appropriate performance on history taking in pediatric adolescent (ages 14 – 19) lower abdominal pain/dysuria/vaginal complaint, or whether that remaining 18% represents potentially uncaptured pathology.  Considering that 76% of patients asked regarding sexual history reported sexual activity, and 83% of their subgroup completing anonymous questionnaires reported sexual activity, I think >90% enquiry regarding sexual activity would be a better target.

So, we’re doing a pretty good job – but it could be better.

“Sexual history documentation in adolescent emergency department patients.”
http://www.ncbi.nlm.nih.gov/pubmed/21646260

Move Over MRSA – It’s VISA and VRSA Time

Is it too late to buy stock in the company that makes linezolid?

This group up in Detroit reviewed 320 patients with MRSA bacteremia and found that 52.5% experienced Vancomycin failure.  Their conclusion states several significant OR for failure, but review of the between-group differences doesn’t show a lot of significant differences.  Nursing homes, for example, were the only p < 0.05, and predicted vancomycin success with a p of 0.02.

What is more important than their clinical predictors, however, is their review of the bactericidal activity of vancomycin – and that higher MICs and higher troughs are needed to effectively treat patients.  I’ve seen our pharmacists recognize this at my hospital as well – the 1g IV Vancomycin standard initial load is transitioning to a weight-based dose.

But, more importantly, what we’re probably really observing is the initial stages of the end of vancomycin’s utility for MRSA.  And, I hate to see what happens when TMP/SMX stops working, too….

http://www.ncbi.nlm.nih.gov/pubmed/21460309

Fluid Boluses Increase Mortality In Children

…or, at least, that’s the gist of the New England Journal Article making rounds in the news.

And, while a close reading of the article doesn’t offer great support for harm, it certainly supports saying that albumin, saline, or nothing were equivalent.

The absolute difference in survival was 3% – and, looking at the demographic breakdown, there were 2-3% differences or trends in favor of the control group regarding dehydration, acidemia, base-deficit, and bacteremia.  Enough that it lets me cling in denial to standard practice and teaching here in the U.S., in addition to whatever you want to say about external validity of a study in resource-poor settings in Africa.

It is an odd and unexpected finding, so say the least.  The authors attribute at least part of the unusual discovery to the high percentage of malaria cases they treated, and that fluid resuscitation in malaria is controversial – but regardless, this is going to be a frequently discussed study on the Pediatric Critical Care side of things for some time.  I also expect follow-up confirmatory studies to be a tough sell to U.S. IRBs.

http://www.nejm.org/doi/full/10.1056/NEJMoa1101549

Pediatric Septic Shock Protocol

Another sort of goal-directed sepsis study, this time in Pediatrics at Primary Children’s.  They implemented a protocolized triage system in their ED designed explicitly identify more cases of sepsis – which led to increased percentages getting early fluid resuscitation, early lactate level measurements, and more frequently antibiotics in the first three hours.

But the net effect of all these interventions…the only detectable difference in their 345 patient cohort was improved length-of-stay for survivors, from IQR 103-328 hours pre-intervention to IQR 86-214 post-intervention.  Total hospital costs were not significantly different.  No change in mortality – which was already low at 7%.
So, yet again – adherence to “quality measures” has debatable clinical significance.

Procalcitonin Misleads Antibiotic Therapy In Sepsis

An important negative study of an inflammatory biomarker that’s been getting a fair amount of push.

It is absolutely true that procalcitonin levels may be elevated in an inflammatory states such as sepsis.  This group tried to make a clinically relevant protocol for procalcitonin trends by saying, if the procalcitonin level is not decreasing with current therapy, then antibiotic coverage should be expanded and aggressive testing should be undertaken to evaluate for missed source control.

Unfortunately, in the treatment arm where procalcitonin was used in clinical decision making, there was extensively greater broad-spectrum and multiple-antibiotic utilization without any demonstrated mortality benefit.  In addition, LOS and ventilator-depended days were longer in the procalcitonin arm.

There were very minor differences between the two groups, probably favoring the control, but not nearly enough to suggest that procalcitonin has any value in assessing failure of current therapy.

http://www.ncbi.nlm.nih.gov/pubmed/21572328

Early Antibiotics Show No Benefit in Sepsis

Interesting analysis of the EMSHOCKNET cohort, looking to see if there was any association between time to antibiotic administration and survival benefit in septic shock.

And, no.  Earlier antibiotic administration, as measured by arrival time in the the ED, showed no significant impact.

They do another secondary analysis where they try to say, well, if the patient received antibiotics before they met criteria for septic shock – then they had a 2.59 (1.17 – 5.74) OR for survival.  I’m not sure how to interpret this finding – perhaps because they looked at 10 different cut-off points for antibiotic administration, they found one that favored antibiotics by chance.

Or, perhaps antibiotics really aren’t the lynchpin in treating sepsis – if you can give antibiotics ahead of SIRS, perhaps you have a milder case – but once you have end-organ dysfunction, the interventions that target improving the physiologic changes of sepsis are more important.

http://www.ncbi.nlm.nih.gov/pubmed/21572327