Inflammatory vs septic arthritis case

[jamiehalap]

Hi all,

 

Had a case tonight that my attending and I both felt a bit wishy washy on and wanted some (kind) opinions on. 45 yo male from the carribean presenting for R knee pain and swelling for 2 days. Also reports warmth to knee as well as chills/feeling feverish. No hx of IVDA. No trauma to the knee. No prior knee surgery. Xray showed large knee effusion and also some osteophyte formation. We were initially thinking along the lines of inflammatory secondary to possible OA. The effusion was actually more suprapatellar. Joint fluid I aspirated was yellowish/blood tinged but still somewhat clear. I would not describe it as purulent. Joint fluid analysis showed yellow/cloudy fluid with a cell count of 41,000 however PMNs of 91%. No organisms seen but abundant PMNs. No crystals. We decided to go ahead with basic labs and crp/esr as well. Wbc 9.3, crp of 124. Sed rate was pending at the end of my shift. Based on the elevated crp and large percentage of PMNs plus a monoarticular joint swelling and decreased ROM we decided to admit for IV abx for probable septic arthritis. It was really not a slam dunk either way and as a newbie PA I would love to hear from you guys.

 

 

Thanks

 

Sent from my SM-G950U using Tapatalk

 

 

[SedRate]

I agree that this one is tricky. The 30-50,000 cell count range is a gray area for a native joint, so I rely on the clinical picture just as much as the lab work. 

Are you in the ED? Did you consult ortho? Did the patient do any abnormal activity or overuse lately? Recent joint injection or aspiration? Pain out of proportion, e.g., ranges approximately 10 degrees with excruciating pain? Other comorbidities besides OA, e.g., diabetes, HIV? I agree with admit for close observation, but from an ortho perspective, I personally would've held off on antibiotics for now since he's non-septic and afebrile. At this point, antibiotics can muddy the waters by suppressing his infection and ultimately his symptoms which are very important to monitor.  

If possible, keep us abreast on the patient's course. I'm interested to find out his outcome. 

[LT_Oneal_PAC]

It’s actually wrong to think <50k WBC non infectious. Anything over 25k increases likelihood ratio 2.9. Anything over 75% PMN suggests infectious. Did you do a gram stain? No great sensitivity but awesome specificity. Further, what’s the risk of delaying antibiotics while awaiting culture? I would say a lot more than giving an inflammatory arthritis abx and stopping once cultures return negative. 

[SedRate]

And that's the beauty of the art of medicine. It's not just some algorithm that we follow. We try to treat the patient and not the labs because as you know, labs can fail us.

The issue is possible negative culture septic arthritis. There's a certain portion that will never come back positive even if antibiotics were held until after aspiration, and that's where clinical picture and clinician suspicion come in. However, the treatment for native joint septic arthritis isn't a single aspiration plus antibiotics; it's typically antibiotics plus serial aspirations or washout. So aspirating once, starting antibiotics, and then waiting until the final culture comes back 4 days later (and possibly negative the whole 4 days) isn't necessarily the best choice either. 

If the patient is otherwise fine and not immunocompromised, admit and follow the clinical picture closely. If patient is the same or worsens, reevaluate. Unfortunately, antibiotics have their own consequences too. 

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3385899/#!po=12.0370

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1754487/

[LT_Oneal_PAC]

I hope you didn’t take it personally. Medicine is an art and many reasonable approaches, and I believe in antibiotic stewardship to a probably a more radical extent than most. I do feel that you are saying I’m taking an algorithmic approach, which I take issue with and something I’ve never been accused of. Personally, in this situation, I think that withholding abx in a evaluation that suggests more likely infectious than not (patient reports fever and warmth if you want to just look at the patient, and significant elevated synovial WBC almost entirely PMN from a more objective stand point) warrants antibiotics before there is joint destruction or, less likely, sepsis. This is an ED perspective, not an ortho perspective. Ortho isn’t worried because when they become septic they just admit to medicine

[SedRate]

I didn't take it personally, but I appreciate you clarifying. Likewise, I wasn't accusing you of practicing algorithmic medicine, at least that wasn't my intention. I was just trying to bring to light that there's more to the equation, at least from an ortho perspective. Starting antibiotics isn't the wrong thing to do. And I'm in agreement with you that this guy's likely infected based on cell count and PMNs alone. However, I do want just a little more evidence if at all possible to absolutely make sure before violating the joint with surgery. With that said, I also don't want to wait until cultures come back because they may never turn positive but symptoms may worsen which is just what I need to decide if my surgeon should cut or not. 

The OP asked for opinions, and me being a consultant, I gave mine from the consultant perspective who will treat the septic joint just as you did from the primary treating ER PA perspective who'd be calling me to consult. Or at least I hope ortho was called for a possible surgical emergency like septic arthritis. The OP also did not specify their field, and to be honest, I initially thought they admitted from an ortho clinic. Ha

[kargiver]

Caribbean patient plus swollen knee is infectious until proven otherwise.  Besides the usual culprits that cause this that are infectious (was this person from the Caribbean or did they visit?), there are lots of bad bugs that circulate there that we don't see in the states, and the spat of hurricanes last year also drudged up other microbes that are usually kept at isolated levels.  You have elevated PMNs, no crystals, a WBC greater than 25K (that's my magical cutoff if one exists) and the potential loss of limb isn't worth the risk of assumption of inflammatory etiology without at least an ortho consult.

Curious - sexual history? Cultural hx?  Native or visitor?  Prior infections?  All play a role here...

G

 

[Arthropathy]

I don't see how you can't treat this as a septic joint until proven otherwise. Admit for IV antibiotics for 24 hours and reevaluate. If not  improved then either drain it again or wash it out. 

It's definitely a grey zone though. Treat as aggressive as you want with close close monitoring and I think deserves a short trigger pull.

 

[ventana]

risk......

untreated infection - huge risk to patient

over treated reactive arthritis - risk to your behind from ID who yells at you.....(but sounds like the guys is getting sick so you would likely be able to throw it back at the ID doc in the YOU saw him and THEY did not....)

 

 

I know which one I would choose...

[Walkoffshot]

Curious.. was a gram stain performed? (I assume it was). That can dramatically change how you treat with abx and can somewhat help clear the mud. Hopefully C&S was done as well... final result would be in by now. Any updates? 

I wouldn't say the cell count itself is impressive for infection but those PMN's are freakin high. At 91% PMN's you have to assume infectious. Maybe contamination... but the patient presents infected. I get fluid reads as "cloudy" that aren't infectious. Could be cloudy because of debris, inflammatory conditions (outside of infection) etc. That said, you would think if this guys knee has been infected there would be frank purulence which is obvious. 

edit: read again, looks like you mentioned no organisms seen.. assuming thats from the gram stain.  

[SedRate]

15 hours ago, ventana said:

risk......

untreated infection - huge risk to patient

over treated reactive arthritis - risk to your behind from ID who yells at you.....(but sounds like the guys is getting sick so you would likely be able to throw it back at the ID doc in the YOU saw him and THEY did not....)

 

 

I know which one I would choose...

Untreated? Aspiration is diagnostic and therapeutic. At least temporarily. Now if the OP didn't aspirate or start antibiotics, then yes, untreated.

Everyone is fixated on starting antibiotics. Yes, that is a second part to treating a septic arthritis. However, to TREAT septic arthritis, you must also perform serial aspirations or debridement. One aspiration plus antibiotics will temporize but won't likely completely treat. Aspirating, starting antibiotics and then waiting 4 days for cultures to come back (which may NEVER come back positive, BTW) also won't treat and will allow time for joint destruction and possibly sepsis. I hope ortho was called for a possible surgical emergency prior to ID or hospitalist. I didn't see this mentioned...

Obviously this is an internet case that only the OP examined. None of us set our eyes in this patient. I'd also be interested to know more info, particularly what the RBCs were, especially given blood-tinged aspirate, since WBC can spill into the joint via hemearthrosis and create an artificially elevated WBC. There's a calculation you can use for the corrected WBC. Also, any documented fever in addition to feverish? 

Anyways, just thoughts from a busy ortho trauma PA whose job includes deciding what to do with the infections, osteomyelitis, and pseudoinfections that others admit or punt

Keep these cases coming. I enjoy the discussion and literature searches.