I understand the patient was an 89 year old lady who presented with fever, incontinence and pain on passing urine; she was also confused and had signs of sepsis with tachycardia and hypotension. She was diagnosed with a UTI and E. coil was grown from a urine sample. She was started on IV Co-amoxiclav. Her ongoing incontinence lead to the skin of her perineum and sacrum starting to become inflamed and she was in danger of falling and hurting herself due to the frequent need to get out of bed to use the toilet. The junior doctor started IV antibiotics and in order to protect her skin and provide short-term support for her incontinence inserted a urinary catheter. The junior doctor was then told off for 1) giving her IV antibiotics instead of orals and 2) inserting a catheter in a patient with urosepsis.
Is there any difference between PO and IV Co-amoxiclav?
There is no difference between PO and IV Co-amoxiclav in terms of their mechanism of action, mechanisms of resistance or spectrum of activity. The real difference between them is in how much active antibiotic the patient receives.
The normal adult oral doses of Co-amoxiclav are either:
- PO 375mg TDS (equivalent to 250mg active Amoxicillin with 125mg of the Beta-lactamase inhibitor Clavulanic Acid) OR
- PO 625mg TDS (equivalent to 500mg Amoxicillin plus 125mg Clavulanic Acid)
- The oral bioavailability of Amoxicillin is about 60%
Using the information above the actual daily total of antibiotic the patient receives from a specific dosing regimen is:
- PO 375mg Co-amoxiclav TDS = 450mg Amoxicillin
- PO 625mg Co-amoxiclav TDS = 900mg Amoxicillin
- IV 1.2g Co-amoxiclav TDS = 3g Amoxicillin
IV Co-amoxiclav gives a higher total daily dose of antibiotic to the patient, resulting in higher serum and tissue antibiotic levels, making it more likely that the antibiotic concentration will be sufficient to kill the bacterium causing the patients infection. For the patient in the scenario above, IV is the correct method of administration: she is septic and therefore you want the antibiotics to get in as quickly as possible and to be at sufficient levels to kill any bacteria present.
IV antibiotics are not always the correct choice. Once a patient is improving then it is good practice to convert their IV to oral antibiotics so that their IV cannula can be removed. This reduces the risk of infections associated with the IV cannula such as cellulitis, thrombophlebitis and bacteraemia. Switching to oral also facilitates the discharge of patients from hospital.
Is there any benefit to using seven days compared to three days of antibiotics to treat a UTI?
The three day course of antibiotics for a UTI should only be used to treat uncomplicated UTIs. An uncomplicated UTI is an infection of a structurally and functionally normal urinary tract in a woman who is not pregnant. All other UTIs (including our septic lady) should be considered to be complicated and these require seven days of antibiotics.
Pyelonephritis is infection of the renal parenchyma and is a more severe infection than a simple UTI. Pyelonephritis should be treated for seven days, or fourteen days if the patient is pregnant.
Is it wrong to catheterise a patient with urosepsis?
It is not wrong to catheterise a patient with urosepsis if there is a good reason for the catheter and the patient is on adequate antibiotic treatment at the time of catheterisation.
Good reasons for catheterising a patient with urosepsis include:
- Accurate monitoring of urine output in critically ill patients
- Relief of acute urinary retention
- Control of a chronic neuropathic bladder or bladder outflow obstruction
- Management of incontinence where repeated wetting has resulted in severe skin breakdown and where other methods to control incontinence have failed
In these circumstances the patient is likely to come to more harm as a result of not being catheterised than they would from the catheterisation itself. Like everything we do in medicine it is a balance of risk to patient safety.
If a patient with urosepsis is going to be catheterised then it is important to make sure they have adequate protection against making their UTI worse. The act of catheterising a patient can push bacteria higher up the urinary tract causing either pyelonephritis or sepsis.
- If the patient is already on antibiotics known to be active against the bacterium causing their UTI then continue to give these and proceed with the catheterisation
- If the patient is not yet on antibiotics OR the antibiotic choice is empirical then wait for laboratory analysis of a urine sample, THEN give the patient a stat dose of IV antibiotics before the catheterisation. My preference is for 160mg of IV Gentamicin 15-30 minutes before catheterising the patient
- In the community setting, if a non-septic patient with a UTI requires catheterising then I would normally recommend PO Ciprofloxacin 500mg 1-2 hours before catheterisation. Make sure the patient hasn’t had a recent UTI due to a bacterium resistant to your choice of antibiotic; the current UTI is likely to be resistant to that antibiotic and unlikely to work. If this is the case choose a different antibiotic, one which the bacterium is sensitive to
Giving antibiotics before catheterising a patient with a UTI won’t prevent all of them becoming septic but it will protect the vast majority.
Are C-reactive protein (CRP) and white blood cell counts (WBC) useful for monitoring in infection?
Microbiologists often ask about patients CRP and WBC when they are called for advice, but there is a feeling amongst some healthcare staff that they are of little value in predicting infection. Microbiologists like to use them, they maybe old hat but used correctly they work!
CRP in infection
CRP is a protein made in the liver which rises in acute inflammation, especially in the presence of an acute bacterial or fungal infection. The normal value is <10mg/L (although lots of biochemistry laboratories have slightly different normal values they are all <10mg/L or thereabouts). From a Microbiology perspective a CRP >200mg/L is definitely raised and indicates a likely infection although it is important to take the individual patient into consideration. There are many situations that can cause a raised CRP, especially soft tissue damage such as surgery and trauma and this should be taken in to account before saying the patient definitely has an infection. CRP often lags behind the physiological or clinical picture by about 24-48 hours and so rather than relying on a single value it is often more useful to have two or more values. In this case a rising CRP is more significant than a single value; in the context of a post-operative patient a rising CRP 3 days after the operation should start to ring alarm bells and suggest that the patient may be developing an infection.
There are two scenarios where a “normal” or low CRP can be misleading:
- Over-whelming infection – some infections are so aggressive that the CRP does not have time to rise e.g. meningococcal sepsis, necrotising fasciitis
- Liver failure – if a patients liver is not working properly then they won’t be able to make CRP (remember it is made in the liver), have a look at the patients albumin and clotting, if these are deranged then the synthetic liver function may be poor and a CRP of 50-100 may be more significant than first thought
WBC in infection
In infection the WBC can go up or down; both are markers of infection and form part of the surviving sepsis guidelines for diagnosing sepsis. The normal range of total WBC is 4-11 x 109/L. If you are expecting a patent to have an infection and the WBC is within the normal range have a quick look at the differential white cell count to make sure all of the cells expected are there. The differential WBC is a list of the types of cells making up the total WBC. The most significant number of cells are the neutrophils and lymphocytes. If either of these cell types are very low (neutropaenia or lymphopaenia) then the total WBC can appear normal even though the other cell type is raised and is “filling the gap” e.g. the total WBC may be 5 x 109/L with a neutrophil count of 0.4 x 109/L and a lymphocyte count of 4.3 x109/L (with other cells making up the rest of the WBC) – the total WBC is normal BUT the patient is neutropaenic so this is entirely consistent with infection.
In my opinion CRP and WBC are both useful markers of infection and the response of infection to treatment HOWEVER they must be looked at carefully and in combination as well as being taken in to the context of the individual patient. One off values of either result without considering what they mean for the patient will lead to mistakes and in that situation are not useful, however used correctly they definitely are a valuable tool in the management of infections.
Some “old fashioned” methods of monitoring are still useful; make sure you know how to use them.
Should the junior doctor have been told off?
In my opinion based on the information I was given the decision to use IV antibiotics in a patient with urosepsis and to then catheterise that patient for incontinence and reduced mobility reasons was correct. The junior doctor could then use the CRP and WBC to monitor whether the patient is improving and when they are, they could be converted to oral antibiotics and the catheter removed.
Do you have any questions that you would like to see answered in a blog? Let me know, but remember I won’t disclose names, give specific clinical advice just discuss the principals of microbiology and the management of infections.