Sometimes you come across a patient who represents the perfect storm of allergies, resistance and contra-indications to antimicrobials that really make you scratch your head to come up with a way of treating them. I’m not complaining! These are the kind of clinical conundrums that stretch the brain cells and make Microbiologists earn their money
One of the most common bacterial infections we see in the hospital setting is cellulitis; an infection of the skin and subcutaneous tissues. Most of these are caused by Gram-positive bacteria such as Staphylococcus aureus and the Beta-haemolytic streptococci. First line antibiotic treatment is usually Flucloxacillin, or Teicoplanin or Vancomycin (if the patient is allergic to beta-lactams such as Flucloxacillin). I have recently got to thinking about new antibiotics that might be useful in the treatment of cellulitis and in particular a new cephalosporin called Ceftaroline, which is supposedly active against all S. aureus including MRSA and the Beta-haemolytic streptococci.
So what have I found out about Ceftaroline? How does it work? Why is it active against MRSA? Read on to discover the answers to these questions and many more about this new antibiotic…
Antibiotic resistance is a major threat to public health. This isn’t just my opinion but also that of Dame Sally Davies, the Chief Medical Officer for England, as well as the World Health Organisation and other numerous national and international groups. It is not only the treatment of infections that will become impossible but perhaps an even greater threat is that surgery will no longer be possible without an unacceptable risk that the patient will die from a postoperative infection; who would want a surgeon to operate on their bowel without the availability of antibiotics to stop bowel bacteria causing peritonitis afterwards?
Sometimes you come across an idea so brilliant and yet so simple that you think to yourself “I wish I’d thought of that!” Well that’s what happened to me at the Federation of Infection Societies annual conference at the beginning of December.
I guess I should start by saying I have no affiliation to, or sponsorship from, any company, pharmaceutical or otherwise. I can therefore say I am totally objective, but I was impressed!
So what was it I was so impressed by? Well, it’s a beta-lactamase… What, a beta-lactamase!?! But they’re bad, they breakdown antibiotics and stop them working, how can they be a good thing? Well, before we consider the beta-lactamase let’s think about why antibiotics can be bad for you.
On the ward round a patient reported to the doctor that she had developed diarrhoea on the antibiotics that had been given for her community acquired pneumonia (CAP). She had already had 5 days of antibiotics and other than the diarrhoea was feeling much better. The doctor noted the patient was afebrile and looked at the blood tests which showed the white blood cell count and C-reactive protein had reduced considerably. Knowing that the hospital antibiotic guidelines said the treatment for CAP was seven days the doctor decided to call the Microbiologist for advice.
The Microbiologist went through the story and the said “okay, you can stop the antibiotics”.
“But the guidelines say we should give seven days”, replied the doctor.
“Yes, but the patient is better” replied the Microbiologist.
“So why do the guidelines say seven days then” persisted the doctor.
Good point thought the Microbiologist…
So why do we have defined durations for courses of antibiotics? Why do these appear to be carved in stone so that no doctor or patient dares to deviate from the principal of “you must finish the course of antibiotics”? Surely the correct length of course is whatever makes the patient feel better?
You are busy reading the culture plates in the laboratory when you come across a sample from the Genitourinary Medicine (GUM) clinic growing a Neisseria gonorrhoeae reported as resistant to Ceftriaxone, Azithromycin, Doxycycline, Cefixime and Ciprofloxacin. What would you do? Would you authorise this as normal or would you do anything else? Hopefully this type of resistance pattern would ring alarm bells and prompt further work, but why?
The rising incidence of STIs
In 2015 there were about 435,000 Sexually Transmitted Infections (STIs) diagnosed in the UK. The majority of these were chlamydia at about 200,000. Worryingly the number of cases of gonorrhoea were over 41,200 (an increase of 53% since 2012) and syphilis 5,300 (76% increase since 2012). A lot of the increase is in men who have sex with men (MSM); 80% of gonorrhoea and 90% of syphilis has been in MSMs.
“Doctor, Doctor, I don’t feel well I think I have a virus”. “Don’t be silly you’re a bacterium, you can’t have a virus?”
My last blog was about the impending doom of the post-antibiotic era and one of the points raised by readers was “what about phages”? Well it’s such a good question that this is going to be the topic of this week’s blog!
Bacteriophages, or “phages” as they are commonly known, are viruses that infect bacterial cells. They attach to the outside of bacterial cells and inject genes into the bacterium which causes lysis and destroys the infecting bacteria. To me they look a bit like the lunar module that NASA launched into space back in the 1960s.
Perhaps one of the most important and worrying studies into antibiotic resistance has just been published in The Lancet. It heralds the end of the antibiotic era…yes yes there has been talk of it for a while but it is NOW HERE...I see you think I’m being melodramatic so read on…
Imagine the scenario of a thirty year old lady with pyelonephritis. Over the past few days she has had worsening loin pain and is now septic with a high fever and rigors. On admission she is fluid resuscitated, started on IV Piptazobactam and given a stat dose of IV Gentamicin as per the hospital empirical antibiotic guidelines. Despite this she remains septic so she is changed to IV Meropenem. The next day the Microbiologists start to get anxious; her blood cultures grow a Meropenem resistant Escherichia coli. The Microbiologist recommends changing the patient to the last line of antibiotics: IV Colistin PLUS IV Amikacin. Despite all of the doctors best efforts this young lady, who has never been in hospital before, dies the following day from uncontrolled sepsis. Later the E. coli from her blood cultures is shown to be resistant to every antibiotic tested! There was simply no effective antibiotic treatment available. Does this sound like an unlikely doomsday scenario? Maybe we need to think again?
On the 18th August amidst great excitement Microbiologists across the land awaited the publication of the new National Institute for Health and Care Excellence (NICE) guideline “Antimicrobial Stewardship: systems and processes for effective antimicrobial medicine use”. So do we finally have the road map to stave off the post antibiotic era? Hmm...I didn’t exactly warm to the document.
Infections due to Pseudomonas aeruginosa, a Gram-negative
aerobic bacterium, can be very difficult to treat because they are often resistant to a number of antibiotics (see earlier blog). Let me illustrate with a recent patient of mine...