Statins May Help Guard Against S aureus Bacteremia

Megan Brooks

October 26, 2017

AALBORG, DENMARK — Treatment with a statin to help lower cholesterol levels may also help reduce the risk of community-acquired Staphylococcus aureus bacteremia (CA-SAB), a population-based case-control study suggests[1].

Overall, the study showed that current statin users had a 27% lower risk of CA-SAB compared with nonusers, with long-term statin use and higher doses associated with even greater protection.

Statins have been shown to have pleiotropic effects that may reduce the risk of S aureus bloodstream infections among users, lead investigator Dr Jesper Smit (Aalborg University Hospital, Denmark) told | Medscape Cardiology.

They have been reported to possess direct antimicrobial effects against S aureus and may also inhibit host-cell invasion by S aureus, the researchers note. Use of statins has also been observed to enhance the ability of phagocytes to kill S aureus.

"Our results indicate that statins may have a place in the prevention of S aureus bloodstream infection, which is a devastating disease," said Smit.

The study is published in the October 2017 issue of Mayo Clinic Proceedings.

Beyond Vasoprotection

Several prior studies have also suggested that statin therapy may protect against infection, the researchers note. In a large Danish study published in 2012[2], statin use was associated with a 20% reduced risk of pneumonia (aOR 0.80; 95% CI 0.77–0.83).

In a US cohort study including 6253 patients[3], statin use was associated with a 26% reduced risk of any postoperative infection (aOR 0.74; 95% CI 0.60–0.90).

There is also evidence that statins are associated with a decreased risk of sepsis, which is often caused by S aureus[4].

Using population-based medical registries, the study team identified 2638 patients with a first-ever CA-SAB, including 368 (14.0%) current statin users, and 26,379 matched population controls, with 321 (12.2%) current statin users. The median age of the study population was 69 years, and most were men (61.3%).

Compared with nonusers, current statin users had a markedly decreased risk of CA-SAB, with long-term use, defined as multiple prescriptions across more than 90 days, offering the greatest protection.

Adjusted Risk of CA-SAB With Statin Use

Statin use Adjusted odds ratio (95% CI)
Former use 1.12 (0.94–1.32)
Current use 0.73 (0.63–0.84)
New use 0.96 (0.60–1.51)
Long-term use 0.71 (0.62–0.82)

The risk of CA-SAB decreased with increasing intensity of statin use. Compared with nonusers, the adjusted odds ratio (aOR) was 0.84 (95% CI 0.68–1.04) for current users with daily dosages of <20 mg, 0.71 (95% CI 0.58–0.87) for daily doses of 20 to 39 mg, and 0.63 (95% CI 0.49–0.81) for daily doses of 40 mg or more.

The association between statin use and reduced risk of CA-SAB was consistent across strata of age, sex, comorbidity level, and statin types and was particularly prominent in patients with chronic kidney disease (aOR for current users 0.51; 95% CI 0.34–0.76) and those with diabetes (aOR 0.65; 95% CI 0.50–0.85).  

"Our findings certainly warrant confirmation in other settings and study designs. The biological mechanisms by which statin treatment may protect against S aureus bloodstream infection should be investigated further, and it would be interesting to explore the potential impact of statins on prognosis among patients with S aureus bloodstream infection," Smit told | Medscape Cardiology.

In an accompanying editorial[5], Drs Daniel C DeSimone and Christopher V DeSimone (Mayo Clinic, Rochester, MN) say this new study "raises the exciting possibility that the pleiotropic effects of statins may also harbor important antimicrobial effects that may exert a clinically relevant benefit by conferring resistance to CA-SAB." The dose effect seen in this study is an important finding, they say.

"This persuasive study should stimulate randomized, placebo-controlled trials examining this effect of statins. Such trials in the case of statins are appealing because these drugs are relatively low cost, can easily be matched against a placebo, and would allow for enrollment at the time of an already-necessary antibiotic prescription," the editorial writers conclude.

The study had no commercial funding. Smit has disclosed no relevant financial relationships. Disclosures for the coauthors are listed in the paper. The editorialist reports no relevant financial relationships.

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