Medical FAQ's Version 2.00
September 1997
Craig Ellis
(Copyright.(c) Craig Ellis 1997)
Part 2 .
The next two sections contain a significant amount of technical
information. It is intended as a very brief overview and introduction
of the subject area. I accept no responsibility for the accuracy or
otherwise of this material. The following are more specific
references for these topics :
Antibiotics
* Antibiotic Guide 1996. S. Lang. ADIS Press. 1995. ( Local NZ
book, most university hospitals produce similar)
* Handbook of Antibiotics, R.Reese. Little Brown and Co. 1993
Microbiology
* Microbiology : An introduction. G. Tortora. Benjamin&Cummings
1997 ISBN 0805385355
* Medical Microbiology and Immunology. Levinson. Lange 1996.
ISBN 0838562256
* Clinical microbiology made rediculously simple. Mark Gladwin.
Medmaster 1997. *** Excellent. My choice.***
Laboratory Medicine
No ideal book in this section, but these are a couple of
suggestions.
* Clinical Laboratory Medicine. K.McClatchey. Williams & Wilkins
1994. ISBN 0683052553
* Medical Laboratory Haematology. 2nd Ed. Butterworth.
7.0 . Medications
7.1 Storage and Rotation of Medications
Medications can be one of the more expensive items in your
storage inventory and there can be a reluctance to rotate them due to
this cost issue and also due to difficulties in obtaining new stock.
Unfortunately, drugs do have limited shelf life. It is a
requirement for medications sold in the US (and most other first world
countries) to display an expiration date. It is my experience that
these are usually very easy to follow, without the confusing codes
sometimes found on food products, e.g. -- Exp. 12/00=December 2000.
I cannot endorse using medications which have expired. But
having said that it is my understanding that the majority of
medications are safe for at least 12 months following their expiration
date. A colleague recently did some aid work in the Solomon islands
and a local pharmaceutical warehouse gave him a number of expired
drugs. They stated that the drugs were safe to use for at least
another 18 months. As with food the main problem with expired
medicines is not that they become dangerous, but that they lose
potency over time, and the manufacturer will no longer guarantee the
dose/response effects of the drug. The important exception to this
rule is the tetracycline group of antibiotics, which can become toxic
with time, there may be others that I am unaware of but it is very
difficult to obtain this information. Let the buyer beware, the expiry
dates ARE there for a reason.
In addition, I recommend that if you are acquiring medications on
a doctor's prescription that when you have the prescription filled you
explain the medications are for storage (you don't need to say exactly
what for), and request recently manufactured stock with distant
expiration dates.
The ideal storage conditions for most medications is in a cool,
dark, dry environment. These conditions will optimise the shelf life
of the drugs. A small number of drugs require refrigeration to avoid
loss of potency. These include insulin, ergometrine, oxytocin and
some muscle relaxants. Others such as Diazepam rapidly lose potency
if exposed to the light.
7.2 Antibiotics
7.2.1 Antibiotic Recommendations. In some cases access to
antibiotics may be very limited. The following is my preferred list
of antibiotics. If your limited in what you can get, I suggest you
purchase and expand in this order. All are good broad spectrum
antibiotics and have different strengths and weakness. I suggest you
purchase an antibiotic guide, most medical book shops have small
pocket guides for junior doctors detailing which drug to use for which
bug and outlining sensitivities.
1st A Broad spectrum Penicillin (e.g.-- Amoxycillin
+Clavulanic Acid)
2nd A Quinolone (e.g.-- Ciprofloxacin)
3rd A Cephalosporin (e.g.-- Cefaclor)
***** If allergic to Penicillin, I would advise A Quinolone as a
first choice with some Metronidazole as a anerobe back-up. Alternative
would be Erythromycin.
7.2.2 Antibiotic Summary
The Bugs:
-----------------
A basic understanding of how bugs (read bacteria) cause infections is
required to appropriately use antibiotics. I will not discuss viral
or other infective agents here. This is not the forum for a proper
discussion, so consider this a brief introduction. There are HUNDREDS
of bacteria, I will only discuss common disease causing ones in man.
Four Classes of Bacteria
- Gram positive ( + ve )
- Gram negative ( - ve )
- Anaerobes
- Others
Gram positive bacteria stain blue and gram negative bacteria stain
pink, when subjected to a gram staining test. It is related to the
presence or absence of a coating in the cell wall of the bacteria.
Anaerobic bacteria are ones which require no oxygen to grow. Bacteria
are also described by their shape (cocci = round, bacilli = oval) and
how they are grouped together (chains, clusters, pairs)
Gram Positive Bacteria ( Gram +ve)
- Staphylococcus: Commonest pathogen iis S. aureus. Gram + cocci in
clumps. Causes boils, abscesses, impetigo, wound infections, bone
infections, pneumonia (uncommonly), food poisoning and septicaemia.
Generally very sensitive to Flucloxacillin as first choice and
Augmentin and the Cephalosporins. A strain which is resistant to the
above, known as MRSA and is currently treated with vancomycin.
- Streptococcus: Gram + cocci in pairss or chains. Most are not
pathogenic in man, except Strep pneumoniae and the Strep pyogenes.
Strep pneumoniae causes pneumonia, ear infections, sinusitis,
meningitis, septic arthritis, and bone infections. Strep pyogenes
causes sore throats, impetigo, scarlet fever, cellulitis, septicaemia
and necrotising fascitis. Very sensitive to penicillins,
cephalosporins, and the quinolones.
Gram Negative Bacteria ( Gram -ve )
- Neisseria meningitidis: Gram -ve coccci in pairs. Common cause of
bacterial meningitis, may also cause pneumonia and septicaemia. Can
be rapidly fatal. Sensitive to penicillins, cephalosporins,
quinolones, cotrimoxazole and tetracyclines.
- Neisseria gonorrhoeae: Gram -ve coccci in pairs. Causes gonorrhoea.
Sensitive to high dose amoxycillin (single dose), Augmentin and also
cephalosporins and quinolones.
- Moxella catarrhalis: Gram -ve cocci in pairs. Common cause of ear
and sinus infections, also chronic bronchitis exacerbations.
Sensitive to Augmentin, Cephalosporins, Quinolones and Cotrimoxazole
and tetracyclines.
- Haemophilus influenzea: Gram -ve coccco-bacilli. Can cause
meningitis (esp. in children under 5), epiglottitis, cellulitis and a
sub group cause chest infections. Sensitive as M.catarrhalis
- Escherichia coli: Gram -ve bacilli. Normally found in the bowel.
Causes Urinary infections, severe gastroenteritis, peritonitis (from
bowel injury), septicaemia. Drug of choice is a quinolone or
cephalosporin.
- Proteus sp.: Gram -ve bacilli. Livees in the bowel. Causes UTI's,
peritonitis (from bowel injuries), wound infections. Drug of choice
is the quinolones.
Anaerobes
- Bacteroides sp. gram negitive bacillii. Normal bowel flora.
Commonly causes infections following injury to the bowel or wound
contamination, causes abscess formation. Treated first choice with
metronidazole or second with chloramphenicol or Augmentin.
- Clostridium sp. Gram positive speciess.produce spores and toxins.
- C. perfringens/C.septicum - common cause of gangrene, treat
with penicillins or metronidazole
- C.tetani - tetanus ) damage is from toxins, not
- C. botulinum - botulism ) the bacteria themselves
- C. difficille - causes diarrhoea following antibiotics.
treat with metronidazole
Others:
- Chlamydia sp: Includes C.pneumonia, responsible for a type of
atypical pneumonia and C.trachomatis, responsible for the sexually
transmitted disease chlamydia. It is best treated with Tetracyclines
or as second choice a macrolide.
- Mycoplasma pneumoniae: A cause of attypical pneumonia. Treated best
with a Macrolide, with a second chioce of a tetracycline.
The Drugs:
-------------------
Penicillins - These act by preventing replicating bacteria from
producing a cell wall. A number of bacteria produce a enzyme which
inactivates the penicillins ( B-lactamase).
A number of varieties:
*Benzyl Penicillin: Injectable preparation. Antibiotic of choice
against severe Strep pneumoniae and Neisseria sp infections such as
chest infections, meningitis and cellulitis.
*Phenoxymethylpenicillin (Penicillin V): Oral preparation of above.
Usually used only for the treatment of sore throat.