Monday, September 30, 2013

Table of Common Opportunistic Infections

Please move your cursor around so you can see this whole table.

Pathogen
Cause
Who gets?
Signs & Symptoms
Diagnosis
Treatment
1st choice
Length of tx
Prevention
Pneumocystis jirovecii pneumonia (PCP)
Fungus and protozoa
CD4 < 200
  • Gradual onset symptoms
  • Fever
  • SOB
  • Dry cough
  • Decreased SAO2 esp with exercise
  • CXR-ground glass infiltrates
  • ABGs
  • Increased LDH
  • immunofluorescent monoclonal antibody test (DFA) to detect Pneumocystis carinii in induced sputum. 
  • TMP/SMX (Bactrim) HD  2 DS tabs tid--First choice.
  • Intravenous Pentamidine--first choice after Bactrim in patients with severe PCP. 
  • Clindamycin + Primaquine
  • Trimethoprim + Dapsone
  • Atovaquone (Mepron)--mild or moderate PCP.
  • Steroids with low PaO2
  • 21 days
  • Bactrim DS 1 a day
  • Dapsone 100 mg a day
  • Mepron 1500mg a day
  • monthly aerosolized pentamidine 
  • may stop prophylaxis after CD4>200 for 3 mo
Coccidio-
mycosis
Fungus
  • CD4 < 250
  • Black men
  • Filipino men
  • pregnant women
  • Pneumonia--Fever and/or
  • cough and/or
  • SOB
  • Brain--headache and/or
  • stiff neck
  • Liver--N/V and/or,
  • jaundice
  • Also, skin sores
  • lymphadenopathy
  • Blood test
  • Complement fixation
  • Blood or tissue cultures
  • CSF fluid
  • Fluconazole
  • Itraconazole
  • Amphotericin B (severe)
  • Posaconazole
  • Voriconazole
  • at least 12 mo and CD4 > 250 for 6 mo
none
cryptosporidium

  • Cryptosporidium a protozoan parasite.   
  • c. hominis
  • c. parvum
  • c. meleagridis 
  • eating or drinking water contaminated with cryptosporidium oocysts. 
  • CD4 <100
  • sudden or slow onset diarrhea 
  • stools watery & frequent but not bloody.
  • Nausea, vomiting, fever, and lower abdominal cramping may also be present.
  • cryptosporidium can infect biliary tract, pancreatic ducts, or the lungs causing major infections in these organs.  
  • stool sample or biopsy of the small intestine  
  • special stain that causes the oocyst to look red.  
  • Other methods include: immunofluorescence (better), enzyme linked immunosorbent assays (ELISAs), and polymerase chain reaction (newest method).  In those with severe diarrhea, one stool sample is usually enough to make a diagnosis but in those with milder diarrhea, several stool samples may be needed.
  • Getting the CD4 count to above 100 will usually resolve cryptosporidium diarrhea.
  •   Replacement of the fluids lost with diarrhea is of utmost importance.  
  • Oral and perhaps even intravenous fluids will be necessary.  
  • The drug nitazoxanide may be given for at least 2 weeks.  
  • In addition, anti-diarrhea drugs like loperamide, diphenoxylate with atropine, and  tincture of opium may be tried. 
  • total parenteral nutrition (TPN) may be needed to give vital nourishment until the person recovers some of their eating and drinking abilities. 
  • Nitazoxanide of limited benefit unless CD4 goes up.
  • Wash hands
  • avoid people and animals with diarrhea
  • avoid: petting zoos, cattle, calves, sheep, lambs, other farm animals
  • wash fruits and veggies 
  • avoid raw fruits/veg unless you have washed them yourself
  • drink bottled water or boil water if water source questionable
Bacterial Pneumonia
  • streptococcus pneumoniae 
  • Haemophilus influenzae
  • pseudomonas aeruginosa
  • staphylococcus aureus 
  • legionella (rare)
  • mycoplasma (rare)
  • chlamydia (rare)
Any CD4
  • Fast onset
  • Fever
  • Chills
  • dry or wet cough
  • chest pain with deep breath

  • CXR (infiltrate)
  • SAO2
  • ABGs 
  • Increased WBC


IV ceftriaxone + 
azithromycin or
clarithromycin or
erythromycin
  • ampicillin/sulbactam
  • aztreonam
  • ceftazidime
  • cefepime
  • cefotaxime
  • ciprofloxacin
  • clindamycin
  • doxycycline
  • imipenem
  • levofloxacin
  • linezolid
  • meropenem
  • moxifloxacin
  • piperacillin/tazobactam 
  • vancomycin
  • 10 to 14 days
  • Pneumovax
  • annual flu shot
  • Bactrim helps
  • Azithromycin helps
  • DC smoking
Cytomegalovirus (CMV)
type of herpes virus--can attack eyes, brain, intestines
CD4 <50
  • No symptoms
  • Vision: Floating black spots,
distorted shapes,
sparks,
light flashes,
loss of periph vision
  • headaches
  • sores in mouth
  • dysphagia
  • abd/rectal pain
  • bloody diarrhea
  • weight loss
  • fever
  • CMV pp 65 ag blood test
  • Must have eye exam for definitive dx in eyes
  • tissue biopsy of lungs, esophagus, intestines, brain
  • MRI
  • LP

Valganciclovir or
  • Ganciclovir  (IV)
  • Foscarnet (IV)
  • Cidofovir (IV)
  • Drug implants-eye--severe dz
  • 3 weeks of twice daily (900 mg bid) Valganciclovir then 900 mg daily
  • May stop when CD4  > 100-150 at least 6 mo. 
  • Must monitor  for anemia (H&H), neutropenia (ANC), renal (BUN/Cr) while taking.
None
Esophageal candidiasis
fungus--a form of yeast, called candida albicans*, glabrata, tropicalis, parapsilosis, krusei, and lusitaniae
*most common
  • Thrush more common in patient with higher CD4 count--200 to 500.
  • as the CD4 lowers to < 100, patients will get candidal esophagitis. 
  • burning pain extending down center of chest over breastbone. 
  • thick whitish plaques extending into throat
  • may be difficult to eat or drink. 
  • no fever.  
  • acidic drinks/foods may make pain worse.  
  • Thrush may have no symptoms at all
  • white cottage cheese-like patches that stick to the roof of the mouth, the tongue, and the mucous linings between the teeth and the cheeks.
  • easily scrape off with tongue blade and leave red base
  • endoscopy
 fluconazole
     itraconazole 

Failure?--May have “resistant” infection. 
 Other options:
  • Voriconazole
  • Capsofungin
  • Amphotericin B
  • Anidulafungin
  • Micafungin
  • Posaconazole
  • 14-21 days
  • Treatment for oral thrush can be for 7 to 10 days. 
Usually, no
Histoplasmosis
fungus, histoplasma capsulatum, lives in soil.  The dirt becomes contaminated by bird and bat droppings.  The person inhales the dust from soil
  • OH and MS River valleys
  • Central US
  • Mid- Atlantic states
  • south-central US, from Alabama to SW Texas
  • Canadian Provinces of Quebec, Ontario 
  • Mexico
  • Central and S. America
  • Africa
  • East Asia
  • Australia
  • Construction  workers
  • farm workers
  • common--fever, weight loss, fatigue, cough, and shortness of breath
  • Signs of serious infection involving body organs other than the lungs are: 1) sores on the skin or inside the mouth; 2) swollen glands; 3) nausea, diarrhea, abdominal pain; 4) problems with brain function--memory or learning problems; problems with speech, movement, or walking;  5) the liver or spleen may be enlarged.
  • histoplasma antigen in urine   blood, fluids from lungs, 
CSF fluid
  • Cultures of the blood, bone marrow, or above mentioned fluids
  • tissue (biopsy) from lymph nodes, liver, skin sores, lungs, or bone marrow   
  • mild or moderate histoplasmosis--itraconazole, PO tid for 3 days then decreased to twice a day for 3 months. 
  • severe disease involving more than one body area, amphotericin B IV for several days, then PO itraconazole for the remainder of the 3 mo.  
  • fluconazole PO QD
  • Brain--amphotericin B QD for 3 mo.
  • Itraconazole and fluconazole are not to be used in the first 3 mo of pregnancy
3 months then lower dose medicine for life
None
Mycobacterium avium complex (MAC)    

  • bacteria mycobacteria avium or mycobacteria intracellulare
  • inhaled or eaten
  • bacteria in the water and soil
  • shower heads!  
CD4 < 50
The symptoms are  similar to that of TB and include fever, night sweats, and weight loss.  Diarrhea and abdominal pain are also common.  

  • culture from blood, sputum, stool, cells from the lungs, bone, or lymph nodes  
  • culture results take 10-21 days
  • high alkaline phosphatase level 
  • anemia.  
Clarithromycin* + Ethambutol and maybe Rifabutin* or
azithromycin + ethambutol
Resistant MAC:
moxifloxacin
levofloxacin
ciprofloxacin
amikacin
streptomycin

Tx may be stopped after 12 months if the CD4 count rises above 100 and remains there for at least 6 months. Once person has had MAC,  must restart treatment if CD4 again goes below 100.
  • Yes--azithromycin 1200 mg PO once a week 
  • or Clarithromycin 
  • or rifabutin
  • or azithromycin and rifabutin  
  • These drugs to prevent MAC, in someone who has never had MAC, may be stopped when the CD4 goes over 100 for more than 3 months, and should be restarted if the CD4 count decreases below 100. 

Progressive multifocal leucoencepalo-pathy (PML)
JC virus destroys oligodentrocytes in the brain
CD4 < 100
  • Symptoms come on slowly--weeks or months
  • Weakness on one side of the body
  • Visual field problem:  When one is looking straight ahead, there is a “piece” of their vision missing.
  • Cognitive problem:  remembering, thinking, knowing, reasoning, judgment, awareness.  
  • difficulty walking 
  • language problems.  
  • one out of five will have a seizure.  
  • CT or MRI (better choice) of the brain.  
  • many fluffy ‘hypodense” (less bright than normal) abnormal tissue areas will be present in the white matter
  • no edema
  • LP will be done to rule out other dz.
  • CSF tested for JC virus 
  • a JC virus viral load can be done to determine just how much virus is present in the brain.   
  • brain bx
  • fatal without ARV
  • HIV medicines
NA
None
Toxoplasmosis
  • Protozoan--toxoplasma gondii
  • eating undercooked meat 
  • accidentally eating “oocysts” from cat feces or in water and soil.  
  • inhale the oocyst into lungs, where it will cause infection there.  
CD4 < 50
  • Brain infection but may also affect lungs or eyes
  • Headache most common symptom
  • nervous system problems, depending on where the infection located in brain.  
  • Fever
  • confusion
  • memory problems 
  • muscle movement problems
  • weakness
  • tremors
  • and even seizures may be present.
  • Severe cases may lead to a coma.
  • symptoms plus
  • toxoplasmosis gondii immunoglobulin (IgG) antibodies  (positive toxo IgG Ab) plus
  • CT or
  • MRI of the brain showing one or several spots in the brain tissue--spots usually have white looking “rings” and swelling around them.  
  • brain bx
  • LP

  • Pyrimethamine + Sulfadiazine + Leucovorin*
or
 Pyrimethamine + Clindamycin + Leucovorin*
or 
Trimethoprim/Sulfamethoxazole (TMP/SMX or Bactrim)
or 
Atovaquone (Mepron) + Pyrimethamine + Leucovorin*
or
Atovaquone (Mepron) + Sulfadiazine
or
Clarithromycin or Azithromycin + Pyrimethamine + Leucovorin*
  • *Leucovorin is folic acid and needed to prevent blood problems that can be caused by the drug pyrimethamine. 
  • Steroids if there is lots of swelling in the brain.
  • Seizure medicines if had a seizure-- Levetiracetam (Keppra) 

  • 6 weeks then all doses of medicines are usually decreased and these smaller doses of toxoplasmosis medicines are continued until the spots on the brain have cleared up, the person no longer has toxoplasmosis symptoms, and the CD4 count has remained above 200 for more than 6 month
  • Yes--Bactrim DS one a day
  • If allergic and Toxo ab is +, take dapsone one a day + pyrimethamine with leucovorin once a week.
  • prophylaxis until CD4 count > 200 for at least 3 months. 
  • Atovaquone (Mepron) can be used to prevent both PCP and toxo.
  • Avoid eating meat that is undercooked
  • avoid cat litterbox
  • wash hands
  • wash fruits & veg











Tuesday, October 2, 2012

HIV treatment failure and starting HIV medicines for the second (third, fourth, etc.) time


If you are starting HIV medicines for the second (third, fourth, etc.) time, you are called treatment experienced.  This is different from starting HIV medicines for the first time.  Some people have “failed” their first HIV medicine regimen and have to start again.  Some people never failed their HIV medicine and can just pick up where they left off.  How can you figure out which category you belong in?  Do you have treatment failure?

What is HIV treatment failure?
     If you read my earlier sections, I told you to think of being married to your medicines--faithful, trusting, and ever so careful.  Choosing a second regimen (or spouse) reminds me of getting remarried after divorce--things are a bit different the second time around.  Hopefully, you have learned the reasons your first marriage (drug regimen) failed and will not make similar mistakes.  The worst thing you can do is not figure out why the marriage (drug regimen) failed because you will be doomed to learn the same painful mistakes again.  
     HIV treatment failure is having to choose one or more different HIV drugs because the HIV drugs you are now taking, have stopped taking, or have taken in the past no longer work.  This is not a good situation to be in.  As of the day I am writing this, there are only 23 HIV drugs available--if you have to scratch one or more drugs off the list because they will never work on your particular virus, it’s not a good thing.  
If you have taken HIV drugs in the past, you are considered “treatment experienced.”  The person who has never taken HIV medicine is called “treatment naive.”
HIV treatment failure is not the same thing as having an allergic reaction, a “toxic” reaction, or bad side effects with a particular HIV medicine. Treatment failure means you have resistance to the medicine and the medicine will never work for you again.  
If you recall from my earlier chapters, resistance develops when HIV is not exposed to high enough doses of medication to keep it from making new virus particles.  Resistance causes treatment failure.  How do you know you have treatment failure”?Your HIV viral load, which may have been “undetectable,” is now inching upward.  Here is an example of treatment failure:
Example #1: Treatment failure

Jim has been taking the three-drugs in one pill, Atripla, for 2 years now.  When he started the medicine, his CD4 was 200 and his HIV viral load was 200,000.  One year after starting medicines, his CD4 was 450 and his viral load was undetectable (less than 48).  The past year, Jim has been taking more out-of-town trips with his job, and frequently runs out of his medicine while he is on the road.  He knows he has been getting careless with getting his refills, but he plans to get back on track.  Today, Jim is in the clinic and his HIV specialist tells him his CD4 is 454 but his HIV viral load is 750. His specialist recommends Jim get a resistance test--an HIV genotype--to see if Jim has treatment failure.  Jim’s resistance test shows that he has a mutation to two of the three drugs that are inside the Atripla pill.  His HIV specialist says that Jim must stop Atripla and start taking a different HIV drug regimen.  

This is an example of treatment failure--Jim’s drugs must be changed and the two drugs that Jim has resistance to will not be active against Jim’s HIV virus, now, or in the future.  Jim is considered “treatment experienced” and has “treatment failure.”


Example #2: Not treatment failure

Marco has been on taking the three-drugs-in one, Atripla, for 9 months.  When he started taking the pill, his CD4 count was 100 and his HIV viral load was more than 1 million.  During today’s visit with his HIV specialist, Marco learns that his CD4 count is 452 and his viral load is undetectable.  Marco tells his HIV specialist that lately, he has been having severe bad dreams--the dreams are so real that he awakens screaming in terror.  He and his partner are getting very little sleep at night.  He thinks the HIV medicine is causing these bad dreams and knows that this is one of the side effects of efavirenz (Atripla contains the medicine efavirenz).  Marco wants the HIV specialist to change his HIV medicine.  
Marco does not have treatment failure--his virus is undetectable so there is no need to get an HIV genotype test to check for resistance.  If Marco ever decided to take Atripla in the future, he could.

The exact definition of treatment failure is this: HIV viral load (on HIV medicines) more than 400 at 24 weeks; or an HIV viral load (on HIV medicines) more than 50 at 48 weeks, or repeated detectable HIV in the blood after one had previously achieved “undetectable.” (See the previous chapter on HIV viral load tests.)  Treatment failure may also include: 
  1. Having undetectable HIV virus but the CD4 count remains quite low
  2. Getting a new “opportunistic infection” (not an IRIS infection--see chapter on IRIS) 
  3. Having a flare-up of an old opportunistic infection after you have been on HIV medicine at least 3 months.  
Who is more likely to get treatment failure? 
Those people with HIV who are more likely to get treatment failure are these:
  1. Starting HIV medicines before 1996 or 1997, when there were not many HIV medicines and they were given one at a time.
  2. Higher HIV viral load before the first HIV medicines were given.
  3. Lower CD4 count before the first HIV medicines were started.  Your CD4 nadir is the lowest CD4 count you have ever had; this is an important number and should always be considered when making any treatment decisions.
  4. Those who have been diagnosed with AIDS.
  5. Those who are depressed.
  6. Those who are using street drugs (cocaine, methamphetamine, heroin, someone else’s prescription pain killers, etc).
  7. Those who are drinking more than 1-2 alcoholic drinks in one 4-6 hour time block on a regular basis--even once a week or once a month is a problem.  
  8. A genotype in the past showing resistance.
  9. Prior HIV treatment failure raises your risk of getting treatment failure again.
  10. Not taking HIV medicines on a daily basis and at around the same time every day; this also includes taking the medicine incorrectly--for example, some medicine must be taken with food.
  11. Missing clinic appointments.
  12. Experiencing drug side effects or a “toxic” reaction to an HIV medicine.
  13. The HIV medicines you are taking, or have taken in the past, were not prescribed to get the maximum benefit for you.  Those with HIV who are not seeing an HIV or infectious disease specialist and are getting their HIV medicine from a family or internal medicine provider may not have received appropriate HIV medicines.
  14. Those who are taking “difficult” HIV medicine regimens; this includes large numbers of pills, taking medicines more than once a day, or any other factors that cause one to miss or stop taking their medicines.
  15. Taking medicines, either prescribed or over-the-counter, which interfere with your HIV medicines (see chapter on drug interactions).  
  16. Individual factors that are unique to one person--how the person absorbs and processes their HIV medicines.
You can see that there are many reasons and risks for treatment failure and every one of these reasons should be considered.  Do any of these reasons apply to you?  What role, if any, did you play in your past treatment failure? 
It is important not to blame outside factors for your past problems with taking your HIV medicine.  This includes factors like pharmacy, paperwork, insurance, family members, job, transportation, etc.  I’m not saying that these factors are not important; however, if you do not look within yourself for the reason you had problems getting or taking your medicine, your next HIV medicine regimen will work as well as the first regimen and you will get treatment failure again.  This is something you must try to avoid at all costs.
How do I know if I have treatment failure?
After a person has achieved undetectable HIV levels, it is not unusual for them to have an occasional “bump” in their viral load--anywhere from 50 to 1000.  The person may have been ill, had an infection, a recent vaccination, all things which may cause a temporary rise in the HIV viral load. The lab may have made an error or used a different test.  If the person has been quite careful not to miss any doses of HIV medicines, one can ignore this blip.  If, on the other hand, the person has been careless with their medicines, this blip can serve as a wake-up call to get back on track.  Another warning sign to pay attention to is how often these blips occur--once a year is okay--more than that, one must be careful that they are not getting careless with taking their medicine. 
If the person having these blips is not missing doses of medicine, then they should look at the time they are taking their medicine.  Are they taking the medicine at the same time every day--within one to two hours of the time they took it the day before?  I see this quite commonly in my HIV clinic; many times the patient rushes to get to their morning clinic appointment and didn’t take their “breakfast” time HIV medicines.  When I ask them when they will get home, the person tells me that he gets to the clinic by taking several buses so he won’t be home until 2 o’clock in the afternoon.  That means that his medicines will be 6 hours late that day; in other words, the blood levels of the medicine are quite low from 8 a.m. until the person takes the medicine at 2 p.m.  
The medicine should be taken at around the same time every day.  If not, the virus is exposed for several hours to low levels of medicine, which will eventually cause the virus to mutate (change) and eventually be able to multiply even when exposed to high levels of the same medicine.  See the previous chapter on resistance.  
If the person is taking the medicine on time, every day without missing doses, is the person taking any other medicines that interfere with their HIV medicines?  An example of this is atazanavir (Reyataz) and heartburn medicine--heartburn medicine lowers atazanavir levels.  See the chapter on common drug interactions for more information. You can also ask your pharmacist, your HIV specialist, your nurse or read about the medicine yourself--either online, or in drug handbooks.
If the person has been taking their medicine quite carefully and not missing their doses, a blip may be ignored.  If, on the other hand, the person says they have been missing quite a few doses of their medicine, and their HIV viral load is more than 750 to 1000, another HIV viral load should be measured.  If the viral load remains above 750 to 1000, an HIV genotype test may be done to check for resistance “mutations.”  
Restarting HIV medicines
An HIV genotype should be done if your HIV specialist thinks you are failing your HIV medicines.  You should have an HIV viral load of at least 750 to run a genotype test; less than this and the test may not be able to be run.  The best time to get the HIV genotype is while you are taking the medicine.  If you have been off your HIV medicine for more than a month, the genotype may not be able to detect virus resistance.
Adding one new drug to the “old” HIV medicines
In some cases, if your HIV virus is more than 50 but less than 1000 and your HIV genotype is not showing resistance, your HIV specialist will add one more drug to your 3-drug HIV regimen.  In other words, your HIV drug regimen is made stronger. Restarting the “old” HIV medicines
The best thing to do if you have been off HIV medicines for more than one month and your HIV specialist is not sure you have resistance is to restart the last HIV medicines you were taking.  This is provided that you are able to restart the same medicine and do not have a reason why this would not be a good idea.  For instance, if your last medicine regimen included zidovudine (AZT), and you now have anemia (a low red blood cell count), your HIV specialist may want you to avoid zidovudine.  
After restarting your last HIV medicines, wait patiently.  If, after several months, you achieve “undetectable” HIV, you can be assured that you do not have treatment failure and you can either stay on these medicines or you can ask your HIV specialist to change to a new HIV medicine regimen--perhaps one that is once a day, or less pills, or doesn’t cause as many side effects, etc. 
If you have treatment failure, your HIV specialist will need to choose new HIV medicines.  The HIV specialist will need to know the results of all your old genotype tests, if possible.  If you have had genotype tests in the past but do not know the results, and are unable to get the results, your specialist may have to make an educated guess about what type of resistance mutations you have.  For example, if you once took the drug efavirenz (Sustiva), and stopped taking the drug for whatever reason, there is a good likelihood that you have a resistance mutation to efavirenz and you will not be able to take this drug again.  The efavirenz mutation is the K103N and it is famous for causing treatment failure in those who are the least bit careless about taking their HIV medicine on a strict daily basis.  
Along with resistance, your HIV specialist should consider your past HIV medicines.  Always keep a record of what HIV drugs you have taken in the past as these medicines are important to know when choosing your next regimen. 
You should know about something called “archived” resistance mutations.  Archived means “filed away” or hidden.  Your new genotype may show no resistance but you do have resistance--it is just hidden.  These mutations will usually show up only when your virus is exposed to the same drug.
Let me give you an example of someone who has archived mutations.  From 2004 to 2007, Shirley took the HIV drugs zidovudine (Retrovir, AZT), lamivudine (Epivir, 3TC) and nelfinavir (Viracept).  Before starting the medicine, Shirley had an AIDS diagnosis with a CD4 of 58, an HIV viral load of 600,000 and she felt bad.  She had thrush (white patches in her mouth) and had lost 30 lbs.  She took the 3 drugs correctly the first several months, then on and off for 3 years.  Her CD4 went up into the 300s, and her HIV viral load went to undetectable after 3 months time.  Shirley regained some of her lost weight and no longer felt sick.  Shirley became careless about taking her medicine and frequently skipped her evening medicines and ran out of medicine for 1 or morej days every month.  Eventually, Shirley decided she was sick of taking HIV medicines and stopped them altogether in 2007.  At the time she stopped the drugs, Shirley’s CD4 was 301 and her HIV viral load was 2500.  Now, in 2010, Shirley comes back to the HIV clinic and wants to restart her HIV medicines.  Her CD4 is 205, her HIV viral load is 101,000, and she has started to lose weight again.  Her HIV specialist runs a genotype test to see if she has any resistance mutations and the test shows no resistance.  The HIV specialist is worried about hidden (archived) mutations but decides to restart Shirley’s old HIV regimen.  Shirley restarts zidovudine, lamivudine, and nelfinavir and she is seen in the office 2 months later.  Her HIV viral load has gone down only slightly, to 78,000, certainly not what her HIV specialist had hoped for.  Shirley gets another test for HIV resistance, and the test shows that she has resistance mutations to two of her 3 HIV drugs. Shirley had archived, or hidden mutations, which did not show until the virus was exposed to the old HIV medicines.  
This is one benefit of restarting your old HIV medicines--”teasing out” archived or hidden mutations.  It’s good to know upfront exactly what type of mutations you have, if any. 
Choosing new HIV medicines
The goal of the new HIV medicine regimen is the same as the goal of the first HIV regimen: to suppress the HIV viral load to undetectable (less than 50) and to keep it undetectable over the long run.   The new medicines are chosen from the US Department of Health and Human Services (DHHS) and the International AIDS Society (IAS) adult treatment guidelines just like the first medicines were, keeping in mind that the drugs you have resistance to must be avoided.  For example, if you have the mutation K65R, you will not be able to use the drug tenofovir (Viread).  
An HIV viral load is checked around 2 to 4 weeks after starting new HIV medicines.  If your viral load is moving toward undetectable, great.  If not, you are either not taking your medicines every day, are taking them incorrectly, or a mistake was made in choosing your medicines.  You may have HIV resistance mutations that were not picked up on your HIV genotype test.  Resistance mutations show up when the virus is “under pressure” from the HIV medicines.  If the virus is not “under pressure” because you are off medicines, the resistance mutations will not show until you take HIV medicines again.  
The best “new” HIV regimen will include 3 “active” drugs.  By active, I mean that each drug is fully effective in maximally suppressing your virus.  Let me explain.  Sometimes, your HIV specialist will recommend you remain on an HIV drug, even though you have resistance to the drug.  There is some benefit to doing this; however, the drug is not considered to be “active.”  The drug is not fighting the virus but is helping in other ways.   
For example, many people have the M184V mutation which is associated with lamivudine (Epivir, 3TC) and emtricitabine (Emtriva, FTC) resistance.  Their HIV specialist nearly always recommends that they continue this drug because it still has a benefit, but it is not considered an “active drug.”  
My CD4 count and HIV viral load are good.  Can’t I just stay off medicine for now?
What about those who have taken HIV medicine in the past and want to stay off HIV medicines--perhaps because they have a good CD4 count and a low HIV viral load?  The results of much recent research shows that HIV treatment, once started, should be continued forever.  Even with a high CD4 count and a low HIV viral load, HIV causes damage and inflammation to the body’s organs and keeping the virus suppressed is of great benefit.  
My HIV genotype shows no resistance, but my provider says I am failing my HIV medicines.  What does that mean?
Usually, an HIV genotype that is done when a person is on a failing regimen will pick up HIV resistance mutations.  If the resistance test shows no mutations, most HIV specialists think it’s just a matter of the person is not taking their HIV medicines.  For example, a person has an HIV viral load higher than 100,000 and the resistance test shows no mutations.  Ninety-nine times out of 100, the person is not telling the truth about taking their medicine.  
Why would a person be dishonest about taking their medicines? Usually, the dishonesty is for a reason--sometimes the person fears upsetting or disappointing their HIV specialist.  I once had a patient swear up and down to me that he was taking his medicine, even though his HIV viral load was in the 600,000 range and his genotype showed no resistance.  Thirty minutes later, he told the nurse he was taking his medicine only once a week.  When the nurse asked him why he had not told his HIV provider, he said, “I didn’t want any drama.”  I laughed when the nurse told me about this, but then I thought about it.  I do give out “drama” when patients tell me they aren’t taking their medicine and perhaps I was getting dishonest answers because of this drama.  Perhaps I need to go easy on the drama.