Community-Acquired MRSA among HIV-Infected Patients Rapidly Rising

16 August 2006 (Reuters Health)—The rates of community-acquired methicillin-resistant Staphylococcus aureus (CAMRSA) infection are rapidly increasing among HIV-infected patients. They have an 18-fold higher risk compared with the general population.

The findings come from a study that included all cases of CA-MRSA seen between 1993 and 2005 at a large HIV clinic in California. Patients with positiveMRSA cultures who had not been hospitalized during the previous year were considered to have CA-MRSA.

Of 425 HIV patients, CA-MRSA was confirmed in 25 (5.9%), lead investigator Dr. Nancy F. Crum-Cianfione of Triservice AIDS Clinical Consortium, San Diego, told participants at the XVI International AIDS Conference. All of the cases occurred after 2002, and between 2003 and 2005, the incidence increased by 17-fold. Fifty-six percent of the CA-MRSA patients were on HAART.

By 2005, the annual incidence was 40 cases per 1000 person-years, compared with 2.28 per 1000 person-years among HIV-negative individuals. This amounted to an 18-fold increased risk among HIV-infected patients.

Soft-tissue infections developed in all of the patients, and 68% had positive nares cultures. In addition, 16% required hospitalization, but none “developed bacteremia or died,” Dr. Crum-Cianfione said.

Multivariate analysis showed that CAMRSA risk factors included the recent use of β-lactam antibiotics (P =.04) and a history of syphilis (P =.02), indicating high-risk sexual activity, Dr. Crum-Cianfione said. Other CA-MRSA predictors were “low current CD4⁺ cell counts and a high maximum log HIV viral load.”

She also pointed out that the majority of patients were in the military, so her group could not consider the effect of sexual preference or practices, or the role of drug use, because of military policies.

Dr. Crum-Cianfione noted that “the most common presentation is abscess of the scrotum or buttock, followed by lower extremity, trunk and upper extremity. Patients typically present with an abscess or carbuncle followed by cellulitis and finally folliculitis.”

Editor's comment. A high rate of MRSA infection in this group seems clear. However, labeling these as CA-MRSA infections on the basis of the information provided may be questionable. These may be health care-related cases of hospital MRSA. These individuals probably had extensive clinic contact. Knowing the antimicrobial susceptibilities and Panton- Valentine toxin production of the strains would be helpful in judging whether these cases are truly caused by CA-MRSA.

Imported Melioidosis Reported in Florida

17 August 2006 (Reuters Health)—Two cases of melioidosis, an infection by Burkholderia pseudomallei, were reported to the Florida Department of Health in 2005. Both patients had recently arrived from Honduras, where the disease is endemic. One case resulted in paraplegia, and the other in death.

In the CDC's Morbidity and Mortality Report for 18 August, Dr. Aaron Kite-Powell, from the Broward County Health Department in Florida, and his co-authors note that B. pseudomallei infection usually manifests as pneumonia, but can also cause septicemia and abscesses. Relapses are common, and the infection can be reactivated years later.

B. pseudomallei, endemic in Southeast Asia, northern Australia, and tropical areas, is classified by the CDC as a category B agent. Risk factors for symptomatic disease include type 2 diabetes, thalassemia, renal or liver disease, and chronic alcoholism.

The first Florida case, a 48-year-old man with a history of diabetes and Guillain- Barre syndrome, presented with back pain, fever, and bilateral lower extremity weakness and numbness. He had recently returned from a trip to Honduras.

He began empiric antibiotic therapy. B. pseudomallei was not identified until the fifth day of his hospitalization, after which he was discharged with a prescription of levofloxacin.

Eleven days later, he returned with severe back and pleuritic chest pain, acute leg paralysis, and sensation loss. MRI revealed an epidural abscess along thoracic vertebrae T6-T10 that led to surgery for spinal decompression. He was discharged to inpatient rehabilitation. None of the antibiotics he received were recommended by CDC guidelines.

An 80-year-old woman from Honduras was the second case. She was hospitalized with pneumonia and fever, headache, weakness, and muscle pain. The next day she had an MI with respiratory complications and died the following day. B. pseudomallei was identified 4 days after her admission.

Follow-up showed that 9 laboratory workers had been exposed to B. pseudomallei under conditions considered to be high risk, including handling the isolate outside of a biosafety cabinet and sniffing an open culture plate. Diagnostic serology showed that none were positive for presence of the bacteria, and none reported symptoms.

An editorial accompanying the report advises physicians to notify the laboratory when specimens are obtained from patients with symptoms, risk factors or history suggestive of melioidosis.

Treatment recommendations include initial therapy for at least 14 days with IV ceftazidime, meropenem or imipenem, and optionally, with oral trimethoprimsulfamethoxazole. Eradication treatment should follow for at least 3 months with oral trimethoprim-sulfamethoxazole and optional doxycycline.

Source: MMWR CDC Surveill Summ 2006; 55:873–6.

“Elite” HIV Patients Mystify Doctors

17 August 2006 (Reuters [Maggie Fox])— As many as 1 in 300 HIV patients never get sick and never suffer damage to their immune systems and AIDS, experts said.

Most have gone unnoticed by the top researchers, because they are well, do not need treatment and do not want attention, said Dr. BruceWalker of Harvard Medical School.

But Walker and colleagues want to study these so-called “elite” patients in the hope that their cases can help in the search for a vaccine or treatments.

So far Walker and colleagues have not been able to find out why certain people can live for 15 years and longer with the virus and never get ill.

Some even appear to have weak immune responses, he noted. “Is it just that these people got infected with a wimpy virus? The answer to that is no,” Walker said.

“Some of the people know who infected them,” he added, and in those cases, the person who infected the “elite” patients always went on to become ill.

A few years into the AIDS epidemic, researchers identified people who were called “long-term non-progressors.”These were patients infected with HIV who did not become ill.

Many have become ill as the years have gone by, and required treatment.

Walker said a few of the long-termnonprogressors were now classified as “elite” patients. But the difference is that the “elite” status is clearly defined by how much virus they have circulating in their blood.

Walker has tracked down 200 elite patients and has now joined up with other prominent AIDS researchers to find at least 1000 “elites” in North America and as many as possible globally.

His team wants to take blood and DNA samples to see what might be different about them. Confidentiality is promised.

IgA Antibodies Neutralize HIV in the Genital Tract

18 August 2006 (Reuters Health [Deborah Mitchell])—High levels of HIV-neutralizing IgA antibodies in the genital tract confer protection from HIV infection, despite frequent exposure to the virus through sexual intercourse.

Researchers have identified a group of female Kenyan sex workers who have remained HIV-negative, despite continuous exposure to the virus through unprotected sex. Neutralizing IgA in the genital tract and blood of these highly exposed, persistently seronegative women has been described by researchers, but no well-controlled studies have been done to confirm a protective role of IgA.

To be included in the study, these persistently negative women had to have repeated sexual exposure to HIV, no evidence of HIV DNA and the absence of neutralizing IgG antibodies.

Dr. Taha Hirbod of the Karolinska Institute in Stockholm and members of the Kibera HIV Study Group in Kenya conducted a nested case-control study that included former participants in a large, randomized trial, between 1998 and 2002, in which the women received monthly treatment with azithromycin as a prophylactic for sexually transmitted diseases and HIV infection. Cervicovaginal secretions were collected and stored at study enrollment.

When the azithromycin trial was finished, Dr. Hirbod's group enrolled 24 women who had become HIV infected and 89 uninfected controls who were matched to the seroconverters by time of study enrollment and sexual risk taking. Although the HIV-infected women were similar to the controls in most respects, such as history of sexually transmitted diseases and age, the seroconverters were more likely to have HIV-2 and also had higher alcohol intakes.

Cervicovaginal secretions were obtained again and IgA was separated out and tested for its ability to neutralize antibodies to clade A, the most common type in Kenya, and to clade C, the most common type in sub-Saharan Africa. The immune assays were conducted off-site using a predefined protocol and the investigators were blinded to the subjects' clinical outcomes.

The controls who remained seronegative throughout the study period had significantly more neutralizing IgA antibodies against clade A with a P value of .03. There was also a protective trend of neutralizing IgA antibodies against clade C (P =.1).