Take the Malaria Drugs when in LOS

[tomc12]

curiousguy,

Vibramycin is completely absorbed by the gut; thus diarrhea is quite infrequent with its use. C. difficile colitis is most often associated with the use of ampicillin/penicillin, cephalosporins, and clindamycin. I would be interested to know your source for saying that antibiotics increase the infection rate of Entameba or Giardia.

[Guest]

Thanks Tomc12 and JacKHAck, you have taken away some of my worries. Remember, I am not a medically trained person, I only like to read about infectious diseases.

Tomc12, it seems you know a lot more about these things than I do, so I guess you are right: I made this conclusion (about antibiotics and parasitic infections) by myself after I got amebiasis and giardiasis when taking antibiotics and having read texts like the following in different kind of medical books:

quote:

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"The resident gut flora protect against colonization of the bowel by pathogenic organisms. Susceptibility to gastrointestinal infection is increased when the normal flora is disturbed, for instance by the administration of antibiotics." (Source: Oxford Textbook of Medicine, 2nd edition, page 5.3)

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quote:

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"Invading organisms must overcome colonization resistance if they are to invade the bowel mucosa. The protective effect can be reduced by antibiotic modification of normal flora, predisposing a patient to infection by pathogens to which he or she may be exposed. Thus, salmonella infection in exposed people is more likely if they are pretreated with streptomycin or tetracycline." (Source: Infectious Diseases, by Bannister, Begg & Gillespie, 1996, page 151)

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quote:

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"When the normal flora is nearly wiped out with antibiotics, both exogenous and endogenous microorganisms are given the chance to cause disease. For example, the infecting dose of a Salmonella strain decreases almost a million-fold after mice are given streptomycin. Patients treated with certain antibiotics that are particularly effective in the gut may suffer from diarrhea, due to overgrowth of yeasts or staphylococci." (Source: Mechanisms of Microbial Disease, 2nd Edition, by Schaechter, Medoff & Eisenstein, page 23)

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I guess it all depends strongly on which type of antibiotic and which type of microorganism is involved: the chance of infection by C. difficile and Salmonella is greatly increased by using some kinds of antibiotics, but probably not so much by doxycycline, although doxycycline is a tetracycline... (see second quote). On the other hand, some kinds of antibiotics, including tetracyclines, are generally effective in reducing the chance and/or severity of infection caused by especially E-coli, V. cholerae and Shigella, which explains the CDC-information of JackHAck.

Still, I am not sure about the relationship between (certain) antibiotics and amebiasis/giardiasis: Tomc12 could be rightful when he doubts if there is any relationship, for I've looked extensively for any specific information on this but couldn't find anything. All I could find was that people with some kind of immune deficiency were more vulnerable to amebiasis. Yet, it sounds very logical to me that it was no coincidence that I caught amebiasis and giardiasis when I took amoxycillin: the amoxycillin wiped out my gut flora, so the amoeba and giardia could easily colonize my gut, as this would have probably not happened when I was not on antibiotics and therefore had my gut already/still colonized by my own, good bacteria...

I hope Tomc12 and others are willing to response to this matter again.

Also, Tomc12, what would you advize me to do when I am using doxycycline as anti-malarial prophylaxis for several weeks in mefloquine-resistant malaria endemic area and I develop persistent diarrhea? Continue the use of doxycycline and start taking a second type of antibiotic and/or metronidazole?

[tomc12]

curiousguy,

Normal bowel flora provides some protection against pathogenic bacteria, but it is hardly foolproof as attested by the numerous cases of traveller's diarrhea. Much of the protective effect is passive-filling the niche with nonpathogenic bacteria leaves little room for the pathogenic bacteria to multiply and cause problems. Take an antibiotic which kills off too many of the nonpathogens allows an increase in the pathogens.

Entameba and Giardia infections depend on ingestion of the parasite and not, as far as I know, a reduction in the population of nonpathogens.

Doxycycline is in the tetracycline family, but has different characteristics. Unlike tetracycline, it can be taken with food and is completely absorbed by the gut-tetracycline is absorbed and then excreted back into the bowel in high concentrations through the bile. That's why diarrhea is rare with doxycycline and not so rare with tetracycline.

If diarrhea develops from an antibiotic, consideration should be given to stopping the antibiotic. If it is a mild case and treatment will be finished in a few days, then you can finish the course. However, if you were taking doxcycline for malaria protection and developed diarrhea, you must stop it because you have to take the doxycycline for another four weeks after you leave the malaria region. In a situation of mefloquine resistance, mefloquine can be given with a 3 day course of artesunate or artemether to overcome the resistance. Another option would be to switch to Malarone.

[Guest]

Thanks a lot, Tomc12, you must be a professor of infectious diseases!

Can you explain to me what you said about the mefloquine and the course of artesunate?

I suppose you were talking about mefloquine/artesunate as a propylaxis. I have never heard that a three-day course of artesunate overcomes the resistance to mefloquine. It sounds like an interesting alternative to doxycycline or Malarone as malaria prophylaxis (Malarone is a last resort for me: expensive!). I guess WHO doesn't recommend it, because of the fact artesunate hasn't yet been approved by the FDA? I have only read about the Thai government recommendation of mefloquine/artesunate-combination as an emergency treatment on the WHO-website.

[tomc12]

curiousguy,

Artesunate can be used for prophylaxis at a dose of 200-300 mg every 5 days and combined with mefloquine for treatment of mefloquine resistance malaria. It can also be combined with pyrimethamine-sulfadoxine. Artemether can be used for treatment but it is much more expensive.

[Guest]

Let me try to recapitulate some of the discussed issues to see if I have understood it well.

One possible drug regime as malaria prophylaxis could be:

- One pill of 100mg doxycycline each day while in mefloquine-resistant area (and continuing two to four weeks afterwards). When diarrhea develops it's best to stop the use of doxycycline and jump unto a regime of 200-300mg artesunate once in each five days. If needed I should treat the diarrhea with an appropiate drug in the meantime.

- If nevertheless symptoms of malaria occur, one possible emergency treatment could be 4 pills of 250mg mefloquine together with artesunate. Then another 2 pills of 250mg mefloquine 6-8 hours later. Then on day 2 and on day 3 another dose of artesunate.

Is this correct? and if so: what doses of artesunate should I take when combined with mefloquine as an emergency treatment?

[Guest]

quote:

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Originally posted by curiousguy:

.......One possible drug regime as malaria prophylaxis could be:

- One pill of 100mg doxycycline each day while in mefloquine-resistant area (and continuing two to four weeks afterwards). When diarrhea develops it's best to stop the use of doxycycline........

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Doxycyline as prescribed by my doctor was to start taking 100mg/day a couple of days before entering risk area and contine for 5 week after leaving risk area.

My further thoughts, considering that Doxycycine is also prescribed for Travellers diarrhea (uhhh, I hate that word, if you have a sudden pain and your running down the lane, diarrhea, diarrhea {it's an old sond}). If diarrhea does develope it's unlikely the Doxycycline so continue with the present course of antibiotics and take some imodium to bung you up till the shits pass.

[tomc12]

For malaria treatment, my understanding is the artesunate dose is 4 mg/kg/day for three days with a single dose of mefloquine 15-25 mg/kg on day three.

One person suggested staying on the Vibramycin and taking Imodium. I wouldn't advise that because of the risk of developing pseudomembranous colitis.

[Guest]

So for malaria treatment I should take the mefloquine only on the third day? Then I guess you have to put a lot of trust on the artesunate, because as you know Plasmodium Falciparum can kill within one day. Do you think artesunate is superior to the western anti-malaria drugs?

I am not keen on Imodium as well, for it only reduces the symptoms and doesn't cure anything. I would use Imodium, for example, when I suffer from diarrhea and I would have to travel on the bus for many hours.

Wouldn't it be wise to take metronidazole when persistent diarrhea develops, and stop the use of doxycycline only if the metronidazole doesn't work? For metronidazole kills some common causes of (tropical) diarrhea (BTW, from previous posts I concluded that the chance of developing pseudomembranous colitis from doxycycline is very small).

[tomc12]

curiousguy,

Artemisinin derivative drugs are rapidly effective and well tolerated, but resistance can develop unless they are taken with one of the slower-acting antimalarials.

For the noninflammatory diarrheas, Imodium works well and makes life a lot more pleasant.

The problem with diarrhea in someone on doxycycline is whether it is related to the antibiotic. If it is, you ask for trouble by taking metronidazole and continuing the doxycycline because you will have to take them for weeks for malaria prophylaxis. If diarrhea develops on this combination, neither drug will be effective. Pseudomembranous colitis may be more likely to develop in this situation and if it does, you have to use vancomycin which is quite expensive.