Duration of preoperative antibiotic treatment did not correlate with the odds of positive valve culture in patients with infective endocarditis treated with surgical valve replacement in a recent study.
To evaluate the relationship between preoperative antibiotics and valve cultures, researchers retrospectively investigated 352 infective endocarditis episodes among 344 patients in a tertiary referral hospital from 2005 to 2016. The primary end point was positive valve culture results. Results were published by the Journal of the American College of Cardiology on June 29.
The odds ratios for a positive valve culture varied by two-day intervals of preoperative antibiotic treatment, ranging from 0.64 (95% CI, 0.61 to 0.68) at day 7 to 0.74 (95% CI, 0.70 to 0.78) at day 13 and 0.98 (95% CI, 0.93 to 1.02) at day 21. A multivariable analysis adjusted for bacterial species, McCabe-Jackson classification, and valve type resulted in odds ratios for positive valve culture of 6.35 (95% CI, 1.94 to 20.78; P=0.002) and 3.93 (95% CI, 1.57 to 9.84; P=0.003) for Enterococcus and Staphylococcus species, respectively.
The study authors noted that after seven days of antibiotic treatment, the additional effect of preoperative antibiotic treatment on valve culture results per two-day interval was minor. Antibiotic treatment beyond 21 days had no influence on culture results. They wrote, “The results of this study indicate that—in particular in staphylococcal and enterococcal infective endocarditis—achieving NVC [negative valve culture] should not be the primary influence on the decision for timing of valve surgery.”
An editorial noted that there was not a direct linear correlation between preoperative antibiotic duration and culture positivity. For staphylococcal and enterococcal infective endocarditis, negative valve culture should not primarily influence the decision making on the timing of valve surgery, and there are diminishing returns to longer antibiotic use, according to the editorial. “If an urgent indication for early surgery is present, the multidisciplinary clinical decision-making team should err on the side of early surgery. To delay surgery to ‘get more antibiotics on board’ is likely not going to lead to any additional patient benefit,” it said.
Another recent study of infective endocarditis found that the risk of this complication of streptococcal bloodstream infections is species dependent. Danish researchers studied national registries to investigate the risk of infectious endocarditis according to streptococcal species. Results were published June 25 by Circulation.
Prevalence of infective endocarditis was 7.1% (95% CI, 6.5% to 7.8%) among 6,506 cases of streptococcal blood stream infections. The lowest infective endocarditis prevalence was found with Streptococcus pneumoniae (1.2%; 95% CI, 0.8% to 1.6%) and S. pyogenes (1.9%; 95% CI, 0.9% to 3.3%). An intermediary prevalence was found with S. anginosus (4.8%; 95% CI, 3.0% to 7.3%), S. salivarius (5.8%; 95% CI, 2.9% to 10.1%), and S. agalactiae (9.1%; 95% CI, 6.6% to 12.1%). The highest prevalence was found with S. mitis/oralis (19.4%; 95% CI, 15.6% to 23.5%), S. gallolyticus (formerly S. bovis) (30.2%; 95% CI, 24.3% to 36.7%), S. sanguinis (34.6%; 95% CI, 26.6% to 43.3%), S. gordonii (44.2%; 95% CI, 34.0% to 54.8%) and S. mutans (47.9%; 95% CI, 33.3% to 62.8%).
A multivariable analysis using S. pneumoniae as reference showed that all species except S. pyogenes were associated with significantly higher infective endocarditis risk, with the highest risk found with S. mutans (odds ratio [OR], 81.3; 95% CI, 37.6 to 176), S. gordonii (OR 80.8; 95% CI, 43.9 to 149), S. sanguinis (OR, 59.1; 95% CI, 32.6 to 107), S. mitis/oralis (OR, 31.6; 95% CI, 19.8 to 50.5), and S. gallolyticus (OR, 31.0; 95% CI, 18.8 to 51.1).
Based on these results, it is reasonable to perform transthoracic echocardiography and transesophageal echocardiography in all patients with a bloodstream infection and high risk of infective endocarditis, the authors said. “In patients with streptococcal [bloodstream infections] with moderate IE [infective endocarditis] risk the decision to perform echocardiography should be carefully evaluated based on clinical suspicion and additional risk factors for IE,” they wrote. “In streptococci with a low IE prevalence it seems adequate to anticipate the clinical course and only perform echocardiography up front in case of either high or persistent clinical suspicion.”