Methamphetamine use increases risk of acquiring HIV, STDs and MRSA

Methamphetamine use is 10% to 20% higher among MSM than in the general population, and 20% to 25% use the drug at least weekly.

Issue: April 2006

ATLANTA – Methamphetamine use may be a contributing factor to the acquisition of sexually transmitted diseases (STDs), HIV and methicillin-resistant Staphylococcus aureus (MRSA) skin and soft tissue infections, according to presentations made here at the 2006 International Conference on Emerging Infectious Diseases.

“We need to work better at integrating STD and HIV prevention into methamphetamine treatment,” said Grant Colfax, MD, co-director of the HIV epidemiology biostatistics and interventions section of the AIDS office at the San Francisco Department of Public Health.

“There is a strong association between sexuality and sexual risk taking among users,” said T. Stephen Jones, MD, of Public Health Consulting in Northampton, Mass.

Methamphetamine leads to serious health problems among men who have sex with men (MSM) and who use methamphetamine products, which include methamphetamines, amphetamines and Ecstasy. “The public health concerns are STDs,” Jones said.

It is also a problem among heterosexuals living in rural areas. “The public health concerns are often the social consequences of addiction, broken families, people who are in deep trouble and also infectious diseases,” Jones said.

When first ingested, methamphetamine causes the user to experience a rush of dopamine, which is associated with high energy levels and increased libido. However, over time, dopamine levels actually decrease permanently. “Long-term methamphetamine users have long-term effects of depression and cognitive impairment,” said Colfax, who is also assistant professor of medicine at the University of California, San Francisco. This leads to the addiction cycle, in which more methamphetamine is needed to recreate that first high.

Adam L. Cohen

There are 35 million users of methamphetamine worldwide, and in the United States, 5% of the total population have tried methamphetamine. “We estimated over one-half million weekly users alone,” Colfax said. “There are more meth users than crack cocaine users now.”

“One thing that is critically important in the relationship between meth and HIV is that methamphetamine use by MSM is much higher than in the general population,” Colfax said. In general, methamphetamine use is 10% to 20% higher among this group than in the general population, and 20% to 25% use the drug at least weekly, he explained.

More sex partners

“Methamphetamine use has been associated with increased number of sex partners, increasing risk of having unprotected sex, increasing risk of having sexually transmitted infections and increasing risk of HIV infection,” he said. Mitchell and Wong found that MSM who recorded “methamphetamine use had twice as many partners in the prior four weeks, were 1.7 times more likely to have gonorrhea, were almost twice as likely to have Chlamydia and were five times more likely to have syphilis,” Colfax said.

In a study of 260,000 people, mostly heterosexuals, researchers found that people who used methamphetamine in the prior 12 months were 20% more likely to have an STD. “This reinforces what we’ve been seeing around MSM for a long time,” he said.

Another study found that HIV seroconversion rates were higher among 4,000 urban MSM using methamphetamine. Researchers followed patients for about 3¼ years. About 15% of the men reported methamphetamine use at baseline, which was a predictor of HIV seroconversion, even after controlling for risky behaviors and coinfections.

“Having unprotected receptive anal (URA) sex with an HIV partner increased a person’s odds by 2.4. We also found that having URA with a partner of unknown status was an odds ratio of 2.8. Gonorrhea, 2.5. Methamphetamine doubled a person’s risk of HIV infection, even after controlling for these well-known behavior factors and other disease cofactors in increasing a person’s risk for HIV attribution,” Colfax said.

Colfax said he does not know why it is an independent risk factor, but suggested that users have more traumatic sex. “We know that people engage in sex marathons. There might be unmeasured condom breakage, misreporting of what actually went on because people don’t remember. It might have to do with partner selection. Perhaps, methamphetamine users come into contact with other users who have higher viral loads because they are not on medication or because they are not taking their medication. Perhaps, it is a network issue, where methamphetamine users are more likely to come into contact with positive partners and not realize it,” Colfax said.

“There are also some interesting questions of whether there can be direct biological effects that increase a person’s risk of HIV infection. There is possible immunosuppression, or possibly changes to blood flow to the mucosa as a result of methamphetamine,” he said, which might independently increase one’s risk of infection.

Skin infections

Methamphetamine users, regardless of gender, have severe skin problems, he said. Their skin ages prematurely, and there are many staphylococcal infections, which may be due to the itching and scratching that result from addiction; many of these infections are MRSA.

“In San Francisco, when we see a meth user with any skin infection, we don’t even bother to use any conventional antibiotics anymore. We assume it is MRSA and treat it,” he said.

“A number of socioeconomic and behavioral risk factors associated with meth use may predispose individuals to MRSA skin infections, such as unclean drug injections, hypersexual behavior and skin picking,” said Adam L. Cohen, MD. Methamphetamine users frequently pick and scratch their skin because their skin “crawls” – that feeling of bugs running over the skin, he explained.

Cohen, an epidemiologic intelligence service officer at the CDC, reported results from a study conducted by the Georgia Public Health Department and the CDC. The researchers performed a prospective, case-control study at three emergency departments and three urgent care facilities in rural Georgia from September to October 2005. They examined 143 patients who were older than 12 and who presented in one of the emergency facilities with a skin and soft tissue infection, and compared them with 284 controls who did not have a skin and soft tissue infection, but another comparable illness.

They took cultures and tested for MRSA.

“Of the 119 case patients included in the investigation, 81, or 68%, had an MRSA infection; 20, or 17%, had methicillin-susceptible S. aureus; and 18, or 15%, had a bacteria other than staph, such as streptococcus,” Cohen said. “In our population, having a skin infection in the past three months was the most significant risk factor for a current MRSA skin infection.”

Ten percent of case patients with MRSA, 9.8% with any skin infection and 1.8% of the controls reported that they used methamphetamine, according to Cohen.

Currently using antibiotics, living in the same household with someone with a skin infection, picking at their skin, living in a crowded household and recently having sex with someone with a skin infection were other activities that were significantly associated with MRSA skin infections, Cohen said. Most of the users inhaled or snorted the drug; only one injected it, he said.

“MRSA caused over two-thirds of all skin infections in the rural Georgia community we studied, which is among the highest recorded rates of MRSA skin infections nationwide. In this rural community, we found many previously known risk factors for MRSA skin infections, such as a recent skin infection, current use of antibiotics and household contacts with someone with a skin infection. In addition, we found a novel association between MRSA skin infection and methamphetamine use in a rural population. Meth use was five times more likely with MRSA skin infections than in patients without skin infections,” he said.

“We concluded that MRSA skin infections among meth users may be contributing to the high rates of MRSA in the rural southeast,” Cohen said. “In contrast to skin infections in most illegal drug users, MRSA skin infections in meth users are not commonly due to unclean drug injections,” he added.

Getting patients into treatment would reduce risky behaviors and, therefore, infection rates among this population. – by Marie Rosenthal

For more information:

Cohen AL, Shuler C, McAllister S, et al. Is crystal meth associated with methicillin-resistant Staphylococcus aureus skin infections? Abstract 378.

Colfax G. Crystal meth and the epidemic of HIV/STD among MSM in the United States. Panel session 10.

Jones TS. Methamphetamine use and infectious diseases. Panel session 10.

All presented at: 2006 International Conference on Emerging Infectious Diseases; March 19-22, 2206; Atlanta.

Lee NE, Taylor MM, Bancroft E, et al. Risk factors for community-associated methicillin-resistant Staphylococcus aureus skin infections among HIV-positive men who have sex with men. Clin Infect Dis. 2005;40:1529-1534.