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Graph with time on the X axis and Plasma Concentration of Drug on the Y axis. IV route increases plasma concentration very quickly and then tapes off. Intramuscular rout and oral route increase concentrations more slowly with the intramuscular route being a bit faster than oral but also dropping off more quickly.
On this graph, t 0 represents the time at which a drug dose is administered. The curves illustrate how plasma concentration of the drug changes over specific intervals of time (t 1 through t 4 ). As the graph shows, when a drug is administered intravenously, the concentration peaks very quickly and then gradually decreases. When drugs are administered orally or intramuscularly, it takes longer for the concentration to reach its peak.
  • List five factors to consider when determining the dosage of a drug.
  • Name some typical side effects associated with drugs and identify some factors that might contribute to these side effects.

Drug interactions

For the optimum treatment of some infections, two antibacterial drugs may be administered together to provide a synergistic interaction that is better than the efficacy of either drug alone. A classic example of synergistic combinations is trimethoprim and sulfamethoxazole ( Bactrim ). Individually, these two drugs provide only bacteriostatic inhibition of bacterial growth, but combined, the drugs are bactericidal .

Whereas synergistic drug interactions provide a benefit to the patient, antagonistic interactions produce harmful effects. Antagonism can occur between two antimicrobials or between antimicrobials and nonantimicrobials being used to treat other conditions. The effects vary depending on the drugs involved, but antagonistic interactions may cause loss of drug activity, decreased therapeutic levels due to increased metabolism and elimination, or increased potential for toxicity due to decreased metabolism and elimination. As an example, some antibacterials are absorbed most effectively from the acidic environment of the stomach. If a patient takes antacids, however, this increases the pH of the stomach and negatively impacts the absorption of these antimicrobials, decreasing their effectiveness in treating an infection. Studies have also shown an association between use of some antimicrobials and failure of oral contraceptives. B.D. Dickinson et al. “Drug Interactions between Oral Contraceptives and Antibiotics.” Obstetrics&Gynecology 98, no. 5 (2001):853–860.

  • Explain the difference between synergistic and antagonistic drug interactions.

Resistance police

In the United States and many other countries, most antimicrobial drugs are self-administered by patients at home. Unfortunately, many patients stop taking antimicrobials once their symptoms dissipate and they feel better. If a 10-day course of treatment is prescribed, many patients only take the drug for 5 or 6 days, unaware of the negative consequences of not completing the full course of treatment. A shorter course of treatment not only fails to kill the target organisms to expected levels, it also selects for drug-resistant variants within the target population and within the patient’s microbiota.

Patients’ nonadherence especially amplifies drug resistance when the recommended course of treatment is long. Treatment for tuberculosis (TB) is a case in point, with the recommended treatment lasting from 6 months to a year. The CDC estimates that about one-third of the world’s population is infected with TB, most living in underdeveloped or underserved regions where antimicrobial drugs are available over the counter. In such countries, there may be even lower rates of adherence than in developed areas. Nonadherence leads to antibiotic resistance and more difficulty in controlling pathogens. As a direct result, the emergence of multidrug-resistant and extensively drug-resistant strains of TB is becoming a huge problem.

Overprescription of antimicrobials also contributes to antibiotic resistance. Patients often demand antibiotics for diseases that do not require them, like viral colds and ear infections. Pharmaceutical companies aggressively market drugs to physicians and clinics, making it easy for them to give free samples to patients, and some pharmacies even offer certain antibiotics free to low-income patients with a prescription.

In recent years, various initiatives have aimed to educate parents and clinicians about the judicious use of antibiotics. However, a recent study showed that, between 2000 and 2013, the parental expectation for antimicrobial prescriptions for children actually increased ( [link] ).

One possible solution is a regimen called directly observed therapy (DOT) , which involves the supervised administration of medications to patients. Patients are either required to visit a health-care facility to receive their medications, or health-care providers must administer medication in patients’ homes or another designated location. DOT has been implemented in many cases for the treatment of TB and has been shown to be effective; indeed, DOT is an integral part of WHO’s global strategy for eradicating TB. Centers for Disease Control and Prevention. “Tuberculosis (TB).” http://www.cdc.gov/tb/education/ssmodules/module9/ss9reading2.htm. Accessed June 2, 2016. , World Health Organization. “Tuberculosis (TB): The Five Elements of DOTS.” http://www.who.int/tb/dots/whatisdots/en/. Accessed June 2, 2016. But is this a practical strategy for all antibiotics? Would patients taking penicillin, for example, be more or less likely to adhere to the full course of treatment if they had to travel to a health-care facility for each dose? And who would pay for the increased cost associated with DOT? When it comes to overprescription, should someone be policing physicians or drug companies to enforce best practices? What group should assume this responsibility, and what penalties would be effective in discouraging overprescription?

Three graphs showing changes in perception from 2000 to 2013. If my doctor does not prescribe an antibiotic when I think one is needed, I will take my child to another doctor. Medicaid insured insured (2000, 10%) and (2013, 25%); commercially insured (2000, 8%) and (2013, 10%). If I expect an antibiotic, I am less satisfied if I don’t receive it: Medicaid insured (2000, 10%) and (2013, 24%); commercially insured (2000, 14%) and (2013, 15%). If would rather give my child an antibiotic that may not be needed than wait to see if she gets better without it.. Medicaid insured (2000, 9%) and (2013, 19%). Commercially insured (2000, 8%) and (2013, 6%)
This graph indicates trends in parental expectations related to prescription of antibiotics based on a recent study. Vaz, L.E., et al. “Prevalence of Parental Misconceptions About Antibiotic Use.” Pediatrics 136 no.2 (August 2015). DOI: 10.1542/peds.2015-0883. Among parents of Medicaid-insured children, there was a clear upward trend in parental expectations for prescription antibiotics. Expectations were relatively stable (and lesser) among parents whose children were commercially insured, suggesting that these parents were somewhat better informed than those with Medicaid-insured children.

Key concepts and summary

  • Antimicrobial drugs can be bacteriostatic or bactericidal , and these characteristics are important considerations when selecting the most appropriate drug.
  • The use of narrow-spectrum antimicrobial drugs is preferred in many cases to avoid superinfection and the development of antimicrobial resistance.
  • Broad-spectrum antimicrobial use is warranted for serious systemic infections when there is no time to determine the causative agent, when narrow-spectrum antimicrobials fail, or for the treatment or prevention of infections with multiple types of microbes.
  • The dosage and route of administration are important considerations when selecting an antimicrobial to treat and infection. Other considerations include the patient’s age, mass, ability to take oral medications, liver and kidney function, and possible interactions with other drugs the patient may be taking.

Fill in the blank

The bacterium known for causing pseudomembranous colitis, a potentially deadly superinfection, is ________.

Clostridium difficile

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True/false

Narrow-spectrum antimicrobials are commonly used for prophylaxis following surgery.

False

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Short answer

When prescribing antibiotics, what aspects of the patient’s health history should the clinician ask about and why?

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When is using a broad-spectrum antimicrobial drug warranted?

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Questions & Answers

how can a doctor treat a person affected by endospore forming bacteria in his/her wound?
Mambo Reply
a 28 years old woman come to your clinic with complain of fever painful genital blisters which express clear fluid when ruptured burning sensation around the bristers what is the diagnosis?
Ramadhani Reply
genital herpes caused by a virus called herpe simplex virus
Doris
what is the reference between selective medium and differential medium?
Tony Reply
the micro flora of air is transient why
Princess
Hello.... Am new here
essien Reply
welcome essien
Muhammad
welcome essien
Beka
classification of gram positive
lissa Reply
classify gram positive
lissa
catalase test is done to differentiate between staph and strep. as staph is catalase positive while strep is catalase negative then staph is differentiate further on coagulase positive and coagulase negative. staph aureus is coagulase positive while staph epidermidis is coagulase negative.
Muhammad
gram positive staph is further differentiated on sensitivity test and manitol salt fermentation test while gram positive strep is differentiated on hemolysis pattern
Muhammad
more about gramm positive
lissa
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lissa
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Blessing
am back any gist
Blessing
taxonomy
Rahul
can i use the graph of bacterial growth for my master's thesis?
Christoph Reply
facultative anaerobic bavteria gives uniform turdibity in nutrient broth why?
Princess Reply
oils and waxes are not sterilized in autoclave
Princess
what is the function of paraffin
Muhammad
@ MAHI because they can grow all over the media from surface to the bottom as they can utilize oxygen or conduct fermentation in its absence.
Online
2.@MAHI Autoclave uses steam under pressure. The steam cannot penetrate through oil and wax. Thus, dry heat sterilization is preferred than autoclave .
Online
thnku
Nadiya
how nutirent agar can converted into blood agar
Princess
thank you
Princess
take a nutrient agar ........and add 5ml blood and put in it ...........!
Nadiya
nutrient agar +blood 5ml+ distilled water =blood agar .
Nadiya
mixed wellllll
Nadiya
hi
Rahul
why agar is not a neutrient source?
Shimul
because it's a general purpose agar only use for growing bacteria
Richa
way is antigen
opaleye
what is antigen
opaleye
antigen is a foreign body that cause activation of antibody?
ASNAKE
Antigen is a toxin or other foreign substance which induces an immune response in the body, especially the production of antibodies.
Shimul
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opaleye
what is pharmacology
Luyenu
a science that studies about the drug
ASNAKE
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Sayid
y
Abdul
Work hard
Anigor
y
Abdul
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Luyenu
What is the major different between gram positive and gram negative bacteria.
Asikur
bacteria kya hai
Mala
content of their cell wall
Doris
koi mujhse basic microbiology ki study k Lea book suggest kro .
Richa
Harley prescott
Vikas
what are the five predisposing factors of opportunistic infections
Asher Reply
1. long term exposure to diseases, that the body immunity weakens.
prosper
2. Nature Of some diseases to weaken body immunity such as, AIDS.
prosper
3. Use of immuno-suppresive drugs.
prosper
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prosper
Low immune is the major cause eg for kaposis sarcoma
Davismith
suitable conditions e.g temp,
Muhammad
what os gnormal flora
kifayat Reply
morphological and genetic classification of bacteria
Potter Reply
what is the morphogical
Bupe
h
Sudhir
morphologycal is defined as relating to the branch of biology that deals with the form of living organisms,and with relationship between their structures.
Nadiya
relating to the form or structure of things .
Nadiya
what is the meaning of lessions
oluwa
i am frim Afghanistan.
wahidullah Reply
iam from iraq
Haidar
and i'm from pakistan
Muhammad
Nice
Amina
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Muhammad
Hlo
Asiya
Hmm
Number
Almustafa Muhammad from Nigeria
Mujtafa
am ustaz Abdulsalam from Ghana
ustaz
am Bupe Chifita from Zambia
Bupe
what is microbiology
Bupe
is the study of invisible micro organism
Mujtafa
microbiology is the study of very too small organisms which we can't see with naked eyes ......in other words ....study of microorganism is called microbiology.
Nadiya
Hello! How Can Microorganisms Be Isolated From The Skin?.. 5 ways if possible. (briefly)
prosper
from skin swabbing is the prefer method worldwide
Muhammad
thanks Muhammad Nauman very much!
prosper
hi
Meek
hi Meek
prosper
are there any other ways pals?
prosper
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Meek
hello Meek Mild.
prosper
Any question or ideas, Meek?😊
prosper
and if a patient have any blister or abscess on the skin then first cut the blister or abscess. inside material is taking by syringe.
Muhammad
in case of fingernail or toenails simply cut a small piece of nail and culture on the appropriate media at a required temperature and time
Muhammad
Again, thanks Mr. Muhammad! I appreciate the help.
prosper
you welcom prosper 😊
Muhammad
what are the media use for skin swab?
Sieh-Mlanwin
blood and macckonkey mostly usededia for skin bacteria
Muhammad
used media*
Muhammad
@ SIEH mostly fungal infection occurs in skin so SDA ( Sabouraud Dextrose Agar) or MEA ( Malt extract agar) are common.
Online
thanks
Sieh-Mlanwin
Microbiologicam source of vitamins
Bachi Reply
what do you mean?
Md
that's example?
Md
hi everyone
Muhammad
such as. c/s media
Md
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Md
just tell me about that ?
Md
where are u from
Muhammad
history of Bactolagy?
Piyush Reply
ask me any question you want on microbiology
Norbuqaari Reply
what is scale up fermenter ? and whict bectetia is benifited in industrial microbilogy ?
Nadiya
can u explain to me wts the meaning of autoclave,and how it doing and ,wt r the equipment to need to do it?
chandi
stem heat under pressure
Nadiya
thnks
chandi
autoclave is a steam heat under pressure .it is use to sterilize the equipment, agar ,petridish broth liquid and many more things....to kill the microbes.......free from microbes
Nadiya
nadiya Scale up studies refers to the act of using results obtained from laboratory studies for designing a prototype and a pilot plant process. do you agree or
Norbuqaari
bectetia is benifited in industrial microbilogy is lactobacilli
Norbuqaari
and
Nadiya
chandi. strong heated container used for chemical reactions and other processes using high pressures and temperatures, e.g. steam sterilization.
Norbuqaari
another
Norbuqaari
who is father of microbiology?
Norbuqaari
anton van leoven hook
chandi
antonie van leeuwenhoek
chandi
thanks
Norbuqaari
what is microbial taxonomy
Ini
what is normal flora
kifayat
normal flora contains the microorganisms which lives on and in our body but can not cause diseases easily....e.g staph. aureus lives on our body they dont cause disease in normal conditions whenever our skin is injured by any cut or wound then they enter into the body and cause diseases
Muhammad
two types of normal flora .... one is the resident normal flora and the other is transient normal flora.....resident normal flora is reside on our body in every condition but transient normal flora changes with the conditions
Muhammad
what is the method used for anaerobic bacteria to grow in the lab other then the candle jar method?
Muhammad
Why those beans water smell
Asiya
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Sebewu
hahahaha
Kwame
Asiya Ibrahim please beans water how? please come clear!
Kwame
what is the purpose of gam staining
Norbuqaari Reply
the purpose of gram staining is to differentiate and classified bacteria and other microbes !
Nadiya
the purpose of gram staining is to differentiate between gram negative bacteria and gram positive bacteria
Leah
thanks Nadiya... Thank you Leah Kalasya..Safari njema!
prosper
remember me in yr prayers norbuqaari ! 🙂
Nadiya

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Source:  OpenStax, Microbiology. OpenStax CNX. Nov 01, 2016 Download for free at http://cnx.org/content/col12087/1.4
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