Mike the Mad Biologist

There is a winner in the War on Drugs: methicillin-resistant Staphylococcus aureus, also known as MRSA. A recent article in the Journal of Clinical Microbiology reached the following conclusion:

Injecting drug users accounted for 49% of CA-MRSA infections but only 19% of the HA-MRSA infections (odds ratio, 4.2; 95% confidence interval, 2.4 to 7.4). Our study shows that a single clone of CA-MRSA accounts for the majority of infections. This strain originated in the community and is not related to MRSA strains from healthcare settings. Injecting drug users could be a major reservoir for CA-MRSA transmission.

There are two basic groups of MRSA: community-acquired MRSA (‘CA-MRSA’) where the infection occurs outside of the hospital, and hospital-acquired MRSA (‘HA-MRSA’) where the infection is happens inside the hospital (also known as nosocomial). CA-MRSA, while sensitive to more antibiotics than HA-MRSA, is a lot more dangerous: it appears to be a better colonizer, and it also produces Panton-Valentine leukocidin toxin (which is both ‘flesh eating’ and targets your white blood cells).

The distinction between HA-MRSA and CA-MRSA is also breaking down: in Massachusetts, many hospital-acquired staph infections are now genetically CA-MRSA. And this is also being seen in San Francisco (italics mine):

The PFGE results showed that 33% of HA-MRSA isolates were USA300. There are two likely reasons for this finding. First, the organism may actually have been nosocomially transmitted. That the strain is no longer limited in the community but has spread into the hospital indicates the severity of CAMRSA infection. This hypothesis is further supported by the finding that the USA300 isolates we found in the HA group exhibit an antimicrobial susceptibility pattern intermediate between those of CA USA300 and the HA non-USA300 types.

Which can lead to this problem:

This finding raises the concern that CA and HA strains may exchange genetic material, resulting in an organism uniquely adapted to produce aggressive SSTI-like CA-MRSA strains which carry the Panton-Valentine leucocidin gene as well as possessing resistance to multiple antimicrobial agents, like current HA strains. Such a development would further complicate efforts at limiting the impact of nosocomially associated S. aureus infections.

This article details is that injecting drug users are a major reservoir of CA-MRSA. In other words, heroin users essentially function as one of the major sources of CA-MRSA, particularly in poor communities.

This brings me to needle exchange, which is one more bit of science the Bush Administration and its Republican servants have lied about. Dirty needles are a major risk factor in the spread of MRSA; also, needle exchange programs are an opportunity to get drug users into medical treatment and/or better living conditions (i.e., not the street) which also lowers the risk of MRSA.

But needle exchange and other programs that help the living conditions of drug users are not popular with conservatives who believe in ‘will-based’ policies. Rather than doing the hard work of reducing a chronic problem, they pontificate about morality.

And meanwhile, the antibiotic resistance problem for all of us gets worse.

Comments

  1. #1 Joseph j7uy5
    July 11, 2006

    So long as you assume that only “those people” get MRSA, and that you don’t have to worry about getting it yourself, it might not seem like too much of a threat. Especially if you don’t believe in evolution.

  2. #2 Mike the Mad Biologist
    July 11, 2006

    Joseph,

    that’s whole foolishness in a nutshell. It’s also why we use the term reservoir. Maybe we need a sexier term like “MRSA-laden insurgents”…

  3. #3 Deacon Barry
    July 11, 2006

    Drug misuse is not a moral problem – it’s a health problem. How do you get this across to the moral majority? Here in Britain we have needle exchange programs, and methadone programs to wean people off heroin. Likewise with alcoholism, people can get Antabuse (Disulfiram).
    It should not matter how people got addicted, the point is to treat the addiction and reserve any moral judgements. You want to encourage people to seek treatment, not put them off by telling them they’re sinners.
    As to HA-MRSA, we nurses are doing our bit to fight it by good hand washing technique, and use of gloves. As a further measure, every bed in the ward, and every clinic room has an alcohol disinfectant hand scrub dispenser. Is it the same in America?

  4. #4 Heather
    July 15, 2006

    I think it’s important to draw attention to the fact that limits on government spending in terms of needle exchange programs and intervention programs for injection drug users may help, not hender, the MRSA epidemic that is occuring in our communities. That said, the answer is not simply needle exhange to stop the spread of MRSA among drug users. IV drug users also may share their drugs, drug making equipment, etc., and many are homeless as well so their living conditions and social networks might also lead to the spread of MRSA. Basically more money needs to be spent to learn why there is significantly more MRSA found in this at risk group.
    As to Deacon’s comment, at least in the hospital I work at in San Francisco there are alcohol disinfectant dispensers in every room and we are succeeding at cutting down on transmission of HA-MRSA strains.

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