Shouldn't treat catheter colonizer

Every day we encounter cases of catheter-related bloodstream infection. With the increasing incidence of Diabetes leading to renal failure, more and more people are going for dialysis. More people in dialysis, more catheter was inserted for the purpose of that. 

Using venous catheter for dialysis came with a risk which is - infection. The catheter is one the favorite place for bacteria to hang out. Produce their biofilm and just stay there forever. You flush it, you wipe it with alcohol, whatever you do, it will not move away easily. 

Then came the decision of attacking them with antibiotics and this is where everything goes wrong. 

To diagnose catheter-related infection, the best method is to quantify the growth from the catheter. Catheter tip culture usually will tell us whether a patient has a catheter-related infection or not. It's difficult to do and labor intensive. Thus, a semiquantitative approach was developed. This method was much easier to do. Just culture the tip of the catheter and try to estimate the number of colonies. More than 15 colonies usually are considered as significant. And this semiquantitative approach must be paired with peripheral cultures. Positive peripheral cultures with positive cultures from the catheter tips usually indicate catheter-related bloodstream infection if both cultures grew the same bacteria. 

Still, this method has a flaw. What if a patient still needs the catheter, so that the tips cannot be taken for cultures. Alternative method was developed, by sending paired venous blood cultures, one from peripheral and one from the catheter lumen. This method, however, will only detect intraluminal bacteria. Logically, those bacteria which colonized the extraluminal area of the catheter won't be picked up. However, this method is easier and it can salvage the catheter. In theory, if a person has a catheter-related bloodstream infection, the number of bacteria from the catheter will be much higher in comparison with peripheral blood. 

To quantify the number of bacteria still possess a challenge in reality. Only a few laboratories are capable of doing that quantification. To make it easier, microbiologist will make an assumption. If the number of bacteria is higher, meaning that cultures will positive first in the Bactec systems when incubated at the same time. So, if blood cultures from the catheter were positive first before peripheral blood cultures, it can be presumed to be catheter-related bloodstream infection. 

This method is the most famous method in all microbiology lab. A lot of research was done and it showed comparable sensitivity and specificity to quantification method. 

Enough explaining on that. 

The issue now is whether we should treat patient with antibiotic if he/she only have growth from the catheter without growth from peripheral blood cultures. 


There are different school of thought on this. The most acceptable one is to look at the patient clinically. If he/she was in sepsis, the best thing to do is to treat as clinical sepsis and if no source of infection found other than the catheter, then the diagnosis of catheter-related bloodstream infection can be made. The catheter needs to be removed as a source control of infection. 

Another acceptable thing to do is, to not treat the patient first, just removed the catheter and change it with a new one (do not use a guidewire to change as some evidence says that it can introduce the infection into the bloodstream). If after removal patient improved, then it should be ok. If not, then treat as clinical sepsis, give antibiotic and try to find another source of infection. 

If the catheter is 'live-saving' as the said but more to 'deadly weapon' for me, what they can do is to try and change it with a new one ( can use guidewire if that is the only and the last place of insertion available), or treat with antibiotics to control patient sepsis. 

The unacceptable way to manage this is when the catheter was not removed, it was not changed, but antibiotics were given with a hope that somehow it will kill the bacteria that colonized the catheter. There is no hope in that. There is only one thing that will happen: 

That bacteria will develop resistance towards that antibiotics. A death sentence to patient

I saw this quite a lot nowadays. 

From susceptible enterococcus became VRE. 

From susceptible Staphylococcus became methicillin resistant. 

From susceptible Enterobacteriaceae became ESBL and CRE. 

All because of the false hope that the antibiotic can do something. It will not. Antibiotic cannot penetrate biofilm. 

I hope that everyone will understand this. As more and more people on dialysis today and in the future, we should be clear on this. I


*p/s: Antibiotic lock therapy will not work. Have you seen antibiotics lock therapy work? It will promote antibiotic-resistant more than giving antibiotic as the lock will be there for long term. Long term for that bacteria to study it and developed their resistant mechanism. Those little bugs are clever and their survival instinct is way higher than us human. 







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