Turkey with all the trimmings, but hopefully not Salmonella…

…or Campylobacter. These are the two main types of food-poisoning caused by your Christmas (or Boxing Day) turkey.

The Food Standards Agency has produced some helpful advice to make sure that your seasonal celebrations aren’t spoiled by some unwelcome guests at Christmas

• If you buy a frozen turkey make sure it’s completely thawed before you cook it by checking there are no ice crystals in the cavity. Also, use a fork to test the thickest parts of the meat. A larger turkey can take up to two days to defrost entirely.
• Don’t wash your turkey before cooking. Washing is more likely to splash food bugs on to worktops, dishes and other foods. Proper cooking will kill bugs.
• Plan your cooking time properly. Follow the cooking times and other instructions on the label or, as a general guide, for a turkey weighing less than 4.5kg, allow 45 minutes per kg plus 20 minutes; for one weighing between 4.5kg and 6.5kg, allow 40 minutes per kg plus 20 minutes; and for those over 6.5kg, 35 minutes per kg plus 20 minutes. All turkeys should be cooked at 180ºC, 350ºF, Gas Mark 4 (after the oven has preheated).
• Check the turkey is cooked properly by cutting into the thickest part of the meat. None of the meat should still be pink and any juices that run out should be clear. Finally, the meat should be steaming hot all the way through.

This is the last post until January, so merry Christmas to all Microbioloblog’s readers and all good wishes for 2011.

I guess that’s why they call it the ‘flu (with apologies to Elton John)

Swine ‘flu is making a bit of a comeback at the moment and we have had two patients admitted to the hospital recently with this infection. But where does the name “influenza” come from?

It’s derived from the Italian word for “influence”. This is because mediaeval physicians believed that this was a disease which was caused by inauspicious astrological circumstances: influenza della stella “under the influence of the stars”. Later medics ditched the theory that diseases were linked to astrology and began to have more sensible ideas, for example, that cold weather was associated with the disease: influenza del freddo.

 

An astrological chart - not the best way of predicting a flu epidemic (Credit commons.wikimedia.org)

Influenza has also had several other names including the grippe. This is not to be confused with The Devil’s Grippe which sounds like a very nasty disease indeed. This is an infection caused by Coxsackie B virus. Patients with this illness – also known as Bornholm Disease – can have very severe pain in the rib cage, which can be so bad that they are unable to take deep breaths. Although this is alarming for the patient, the good news is that they will make a complete recovery.



I’d love a glass of wine, but “no thanks” because….

…I’m taking antibiotics.

This was the response I got when I offered to buy a colleague a drink at a Christmas outing recently.

Many people think that if you are taking any antibiotic you should avoid your favourite tipple.

Nice...but not with metronidazole (Credit commons.wikimedia.org)

 

In fact, this advice really only applies to the antibiotic, metronidazole. This is used to treat a number different of infections including dental infections in patients who are allergic to penicillin. If you knock back some alcohol while taking metronidazole you may experience palpitations;  facial flushing; (which may lead your drinking companions to think you’ve gone a bit too far); nausea and vomiting (ditto) or a splitting headache (which may lead you to think that you’ve gone too far).

Sniffing out the problem

An elderly patient was admitted to our hospital recently. She had diarrhoea and had become quite dehydrated. The diarrhoea had started after she had been given two courses of antibiotics for a “chesty cough” by her GP. When I arrived on the ward to see the patient, the nurses had already made the diagnosis – Clostridium difficile infection.

This is an infection which is fairly common and elderly patients are most at risk. Antibiotics wipe out the “good” bacteria which normally live in the large bowel, but don’t kill off Clostridium difficile. The bacterium can then grow in the bowel and produce toxins which damage the lining of the intestine. It is this damage which results in the diarrhoea. The infection is easily treated with antibiotics (such as metronidazole) which kill the Clostridium difficile. If treatment is not started promptly the damage to the bowel can become more severe and this can lead to nasty inflammation of the bowel known as colitis. In the most extreme cases, bowel perforation can occur.

Diarrhoea in an elderly patient being treated with antibiotics could be caused by Clostridium difficile. Courtesy Public Health Image Library

So, why were the nurses so confident about their diagnosis? The smell of the patient’s motions! Several studies have shown that nurses are quite accurate in diagnosing Clostridium difficile by using their noses. Scientists are now working on technology which will detect certain substances in the odour given off by diarrhoeal stools with much greater accuracy.

Were the nurses correct this time? Yes, they were! The stool specimen we received in the lab tested positive for Clostridium difficile. The patient was started on metronidazole and is now recovering well.

When is a penicillin allergic patient not penicillin allergic? (part 2)

(Click here for part 1)

I was called recently about a young patient who had been admitted to the hospital with a chest infection. The patient had been treated with an antibiotic called amoxicillin (a type of penicillin). After a few days of treatment the patient, didn’t seem to be improving and had also developed a rash. The doctor on the ward suspected that this was a penicillin allergy and asked me for an alternative. This was a reasonable explanation for this rash, but there was also another explanation. Might it be the infection and not the antibiotic?  A chest infection in a young patient with a rash, especially occurring during winter time, could be caused by a bacterium called Mycoplasma pneumoniae.

 

This could also explain why the patient was not getting better with amoxicillin treatment as Mycoplasma isn’t affected by penicillins, like amoxicillin. (This is because penicillins attack bacteria by preventing them from making new cell wall. Mycoplasma, is a very unusual bacterium – it doesn’t have a cell wall and so it isn’t affected by penicillins).

A blood test confirmed our suspicion – the patient did have a Mycoplasma infection. We changed the amoxicillin for another antibiotic (clarithromycin) and the patient is now on the mend.

Diagnosing pneumonia by examining urine…

I was asked today about a patient who had been admitted to our hospital with a nasty bout of pneumonia. Cultures of the patient’s sputum hadn’t grown anything significant and the other lab test which is often done in cases of pneumonia – blood culture – was also negative. (Blood cultures are taken in pneumonia because, in a significant number of cases, bugs can get from the infected lungs into the blood. Bugs can also reach the lungs through the blood stream, but this is much less common). The negative cultures probably reflect the fact that the patient had received antibiotics from his family doctor before admission to hospital. These may have inhibited the growth of bacteria when the specimens were incubated in the lab. So what else could be done to help make a diagnosis? The junior doctor on the ward was surprised when I asked for a urine specimen from the patient. So, how can a urine specimen be used diagnose pneumonia?

 

Pneumococcus growing in the lab - the usual way of diagnosing pneumonia caused by this bacterium (Courtesy Public Health Image Library)

Well, we don’t culture the urine: we look for fragments of the bacteria causing the pneumonia which have been excreted by the kidneys into the urine. These fragments, or antigens, can be detected in the lab using technology which is similar to that used in home pregnancy testing kits. The test can detect antigens from pneumococcus (which is the commonest cause of pneumonia contracted outside hospital) and also Legionella pneumophila, which causes Legionnaires’ Disease. Using this test we were able to confirm a diagnosis of pneumococcal pneumonia which allowed us to “fine tune” the patient’s antibiotic therapy and hopefully speed his recovery.

Bugs delivered to your doorstep

Our daughter invited a friend for a sleepover this weekend. At the breakfast table on Sunday, her friend was surprised to see milk for the breakfast cereal appear from the refrigerator in a glass bottle. Many people buy their milk from the supermarket which is sold in plastic bottles, but we still have ours delivered by the local milkman and it comes in glass bottles. One thing I always do as I bring in the milk from the doorstep is to check to metal foil bottle tops. If there is a hole in the top, then I pour the milk away.

Why? Well, because the hole was probably made by a bird pecking through the foil to enjoy some early morning refreshment. If the bird was a magpie or a jackdaw it may have had a bacterium called Campylobacter jejuni on its beak and as it pecks through the foil, the milk in the bottle can become contaminated with this bug – which is the commonest cause of bacterial food poisoning in the UK. If you can’t bear the thought of tipping the milk down the drain and use it, then you may be setting yourself up for a nasty stomach upset.

How does the Campylobacter get onto the birds’ beaks? It has to do with their (not very pleasant) feeding habits which see them foraging in all kinds of unsavoury places where this bacterium is found – including sewage plants. Yeuch.

He might spoil your breakfast (Credit Michael Nash)

So enjoy your “pinta” delivered by your local milkman or milklady and produced on your local dairy farm, but be careful with bottles with pecked tops!

 

Foot and Mouth Disease and Hand Foot & Mouth Disease – what’s the difference?

Quite a big one! Foot and Mouth Disease is a viral infection which affects animals such as cows, sheep. Large outbreaks of infection can occur – there was a really big one in the UK in 2001.

Hand foot and mouth disease is an infection which is only seen in humans. Infection is commonest in toddlers and young children and outbreaks can occur in nurseries and primary schools. One of the signs of the disease is the appearance of small blisters – vesicles – on the hands, feet (usually the soles and palms) and around and inside the mouth. Fortunately, this is a mild infection which soon clears up.

Coxsackie virus – the cause of hand, foot and mouth disease

(It’s called Coxsackie after a town in New York State)

(Credit: Public Health Image Library)

Today I took a call from a GP about a pregnant woman who’d had contact with a girl with hand, foot and mouth disease. The patient was concerned about the possible effects on the baby if she were to catch the disease from the girl.

I’m often asked about cases like this and was happy to reassure the doctor and her patient that there were would be no risk to the baby even if Mum were to come down with the disease. I think I get called in situations like this because there is confusion between hand, foot and mouth and another infection which is associated with a rash – slapped cheek syndrome – as this can, under certain circumstances, have implications for the pregnancy.

I’ve heard of smallpox…but what about bigpox?

Smallpox is a deadly viral infection which once killed millions of people every year. Thankfully this killer disease was finally eradicated by 1979 – a tribute to the success of vaccination. But the name smallpox suggests that there might be a disease called bigpox…and if there is a bigpox, what kind of a disease is it?

Well, there is a “bigpox” or “great pox”, it’s just that these days it’s called syphilis. Back in the 1500′s the doctors of the time recognised that the rash of the early stages of syphilis looked similar to that of smallpox, although the two diseases went on to have quite different outcomes.

Girolamo Fracastoro – the man who brought you syphilis

(Credit: National Gallery, UK)

OK, it’s no longer called the “great pox”, so why is it called syphilis? The name is taken from a poem by an Italian doctor (and poet), Girolamo Fracastoro (1478-1553). Syphilis was the name of the shepherd in the poem. As punishment for bad behaviour he was cursed with the really nasty disease, which was named after him, by one of the gods.

Can bacteria swim?

Yes they can. Many bacteria produce long whip-like structures called flagella. They use these to move through liquid environments. A patient was recently admitted to our hospital with a nasty urine infection. By looking at the culture plates I could tell it was caused by the bacterium, Proteus. This bug has flagella which allow it to “swim” across the culture plate and instead of the round colonies which many bacteria produce, Proteus has very flat ones which spread across the Petri dish. (I might also have got a clue that the infection was caused by Proteus by smelling the patient’s urine sample. Yeuch! Proteus produces an enzyme which converts a chemical found in urine – urea – into ammonia.  So a strong smell of ammonia can be an indication of Proteus infection).

Proteus swimming (“swarming”) across an agar plate

(credit: ASM MicrobeLibrary)

However when it comes to swimming Proteus is left way behind by a bacterium called Bdellovibrio. This bug swims so fast that it can cover 100 cell lengths every second – that’s the equivalent of a human travelling at about 400 miles per hour…