Multi-drug resistant Shigella

Public health authorities in the UK have issued a warning about a highly drug-resistant strain of a serious bacterial gut infection that can be contracted through sex.

Between March and November last year, 17 cases of Shigella dysentery with resistance to several first-line antibiotics were detected. It seems that most people affected are gay men.

Standard treatment with first line antibiotics such as azithromycin and ceftriaxone may not be effective, though other oral antibiotics will still work.

Shigella is transmitted by contact with very small amounts of human faeces (shit) and can be passed on during sex. Rimming, fingering, fisting, anal sex, handling sex toys after use in the anus, and occasionally oral sex can all carry a risk. The bacteria may pass from fingers to the mouth.

Using condoms for anal sex and latex gloves for fisting, as well as washing hands frequently, can help prevent transmission of Shigella.

Symptoms typically occur within three days of exposure and include:

• Frequent diarrhoea lasting more than 48 hours
• Stomach cramps
• Fever
• Vomiting
• General weakness and tiredness.

Shigella can be especially serious in HIV-positive individuals who have a low CD4 count.

If you have these symptoms, go to see your GP or a sexual health clinic, mentioning Shigella.

For more information, read NAM's factsheet 'Shigella'.

Weight gain after starting HIV treatment

Putting on a little weight after starting HIV treatment is quite common and is associated with a general improvement in health.

But some doctors are concerned that some people beginning HIV treatment from the integrase inhibitor class are putting on more weight than this. What’s more, the issue seems to particularly affect women and black people – groups which are frequently under-represented in the clinical trials which test the safety and effectiveness of new medications.

For the moment, the data on this issue is incomplete. A group of British doctors have called for more research into the issue.

Integrase inhibitors are a relatively new class of anti-HIV medications and are often recommended for first-line HIV treatment. Four integrase inhibitors are available: dolutegravir (Tivicay, also in Triumeq and Juluca), elvitegravir (in Stribild or Odefsey), bictegravir (in Biktarvy) and raltegravir (Isentress).

Several randomised controlled trials comparing an integrase inhibitor to a boosted protease inhibitor have shown greater weight gain in people receiving an integrase inhibitor. Studies have typically reported average gains of between 1kg and 4kg over one to two years of follow-up.

There have also been a few observational studies (which provide less reliable evidence than randomised controlled trials) showing greater weight gain in people starting or switching to integrase inhibitor treatment, especially in women.

Over the next year, a few more randomised controlled trials will report their results. These are comparing treatment that includes dolutegravir with treatment that includes efavirenz (a non-nucleoside reverse transcriptase inhibitor). Importantly, they are all being conducted in African countries, so will give us more clarity on this issue in relation to black people and women.

For more information, read 'Maintaining a healthy weight' in NAM's booklet 'Nutrition'.

Does HIV treatment always work?

Estimates of how often people on HIV treatment do not have an undetectable viral load are important to gauge the potency of HIV treatment. They can also answer the question of how often people with HIV remain undetectable and are therefore unable to transmit HIV during sex

A new analysis has calculated this for a single-drug regimen – efavirenz, tenofovir and emtricitabine. This was the most frequently used combination for people starting treatment in high-income countries between about 2006 and 2014. Since 2007 it has been available as a combined pill called Atripla. This combination remains very widely used in lower-income countries.

However, efavirenz-based regimens are no longer the preferred first-line regimens in European countries, so this study is a historical look back. Efavirenz is no longer in favour because newer drugs have fewer side-effects and fewer problems with drug resistance. Newer HIV treatment regimens probably have lower failure rates.

The researchers analysed data on almost 20,000 people in 12 European countries who started HIV treatment with efavirenz, tenofovir and emtricitabine between 2006 and 2014. They found that 6.3% of people experienced virological failure (a viral load above 200 copies/ml) in the first year on treatment, but that the rate declined to 3.5% in the second year and was down to about 1.7% by the seventh year.

The annual rates of switching to a different drug combination, with or without virological failure, were 13.6% in the first year and 8.5% in the second year, declining to about 5.5% per year by year seven. These rates are low considering the side-effects of both efavirenz and tenofovir.

People who had a high viral load before starting treatment (above 100,000 copies/ml) were more likely to have a viral rebound than people starting treatment with a lower viral load. Heterosexual women, heterosexual men and male injecting drug users were more likely to have problems with treatment than gay and bisexual men.

For more information, read NAM's factsheets 'Efavirenz' and 'Atripla'.

Efavirenz in pregnancy

Several years ago, there was concern about whether the anti-HIV drug efavirenz (also included in the Atripla combination pill) was safe to use during pregnancy. There had been a small number of case reports of neural tube defects in infants exposed to efavirenz at the time of conception or early in pregnancy.

With time and more data, these concerns have proven to be misplaced. A new analysis of almost 25,000 pregnancies shows that the rate of birth defects in babies born to mothers taking efavirenz was no higher – and may even have been lower – than in babies whose mothers were taking other antiretrovirals.

For more information, read NAM's factsheets 'Efavirenz' and 'Having a baby'.