EMERGING TRENDS IN INFECTIOUS DISEASE
( continued from page 9 ) in the table from the estimable antimicrobial stewardship sage Dr .
Brad Spellberg , shorter is better . 3 The diagnoses for which shorter is better include everything from community acquired pneumonia to osteomyelitis to febrile neutropenia , chronic osteomyelitis , gram negative bacteremia , latent TB , UTI and more . Using a shorter course of therapy decreases the length of stay and the chance of side effects and mitigates the development of antibiotic resistance .
Trend 3 : That positive test may not require treatment : not all bugs need drugs . 4 , 5
In the first century AD , Celsus identified four cardinal signs of inflammation : calor ( heat ), dolor ( pain ), rubor ( redness ) and tumor ( swelling ). For the next 2,000 years , those four signs formed the basis of diagnosing infection . Since the advent of Polymerase chain reaction ( PCR ) testing in the 1980s , however , clinical microbiology labs have increasingly relied on nucleic acid amplification tests ( NAT ) to diagnose infection . NAT are approved both for detection of a single microorganism , such as a Hepatitis C viral load in the blood , or as “ syndromic panel ” which tests for multiple microorganisms in a single specimen . Perhaps the most well-known syndromic panel is a respiratory pathogen panel which detects up to 20 bacteria and viruses commonly implicated in upper and lower respiratory infection . Other examples include cerebrospinal fluid ( CSF ), gastrointestinal ( GI ) and panels designed for bacteremic patients .
The benefits of these often rapid tests are manifold . For instance , within minutes of detecting gram positive cocci in a patient ’ s blood ,
10 LOUISVILLE MEDICINE a NAT can distinguish between a probable contaminant and clinically insignificant coagulase negative staphylococci versus a virulent MRSA or MSSA . On the other hand , these tests target genetic material and cannot distinguish a dead or nonviable organism from those living and viable . This is much the same way that the investigator cannot tell , based on DNA analysis alone , if the blood left at a crime scene is from someone living or deceased .
The inability to distinguish between active infection and inactive organism has led to considerable difficulty in interpreting COVID-19 testing , for instance . To press the case , consider the example of a C . difficile PCR . In an adult patient recently treated with clindamycin presenting with copious watery diarrhea , a positive C . diff test represents true infection . In a one-year-old , a positive C . diff test is much less clear and is likely colonization . So when considering a positive test , especially from a “ non-sterile ” site such as the GI tract , bladder or oropharynx , we would be wise to look also for calor , dolor , rubor and tumor . In short , to borrow from another medical aphorism made famous on radiology reports across the world : “ Clinical correlation recommended .”
Trend 4 : You can probably treat that infection with oral antibiotics
Once a dogma that patients with bone and joint infections and bacteremia required IV antibiotics , recent literature has challenged the inferiority of oral antibiotics . The Oral versus Intravenous Antibiotics for Bone and Joint Infection trial published in 2019