Lyme disease study finds frequent misdiagnosis, unnecessary antibiotics

Data from a single-center study indicate widespread misdiagnosis of Lyme disease and unnecessary antibiotic treatment, particularly among those with unexplained symptoms lasting longer than 3 months, a team of US researchers reported today in Open Forum Infectious Diseases.

In the retrospective study, researchers reviewed data on patients referred to an outpatient infectious disease clinic of the Johns Hopkins University School of Medicine for Lyme disease consultation from 2000 through 2013 and analyzed diagnoses and treatments. They then compared clinical characteristics of those with Lyme disease and those who were misdiagnosed to evaluate variables that could be useful for predicting when Lyme disease would not account for consultation complaints.

Of the 1,261 patients included in the study, 911 (72.2%) did not have Lyme disease, 184 (14.6%) had active/recent Lyme disease, 150 had (11.9%) had remote Lyme disease, and 16 (1.3%) had possible Lyme disease. Multivariable analysis showed that patients without Lyme disease were more likely to be female (odds ratio [OR], 1.56; 95% confidence interval [CI], 1.08 to 2.25), have symptoms for more than 3 months (OR, 8.78; 95% CI, 5.87 to 13.1), have higher symptom counts (OR per additional symptom, 1.08; 95% CI, 1.02 to 1.13), have more Lyme-related laboratory testing (OR per additional laboratory test, 1.17; 95% CI, 1.03 to 1.32), and to have been diagnosed with what were regarded as co-infections (OR, 3.13; 95% CI, 1.14 to 8.57).

Of the 911 patients without Lyme disease, 764 (83.9%) received antimicrobials to treat Lyme disease or their co-infections. In addition, 53.4% of patients received antibiotics for longer durations than recommended regardless of their diagnosis. The percentage of patients established to have Lyme disease was lower than in earlier studies of referred populations.

The authors of the study say the findings suggest that Lyme disease appears to be an attractive diagnosis for otherwise unexplained, longstanding problems that are referred to by some as "chronic Lyme disease," a term that does not have consensus medical definition.

"This thirteen-year study suggests that patients and clinicians may be influenced by alternative, non-evidence-based medical practices, or could be confused by non-validated laboratory test results or interpretations," they write.

Jul 5 Open Forum Infect Dis abstract

Study: Gut persistence could aid spread of pandemic urinary E coli clones

A study yesterday in Clinical Infectious Diseases indicates that two pandemic, uropathogenic Escherichia coli strains have the ability to persist in the gut and cause bacteriuria in healthy women.

In an analysis of 1,031 fecal samples from women with no documented urinary tract infection (UTI), researchers from the University of Washington School of Medicine found that 88.8% (916 samples) contained E coli and 8.8% (91 samples) yielded fluoroquinolone-resistant E coli isolates. Among these isolates, 14 distinct clonal types were identified, with E coli ST131-H30R and ST1193—the two most dominant multidrug-resistant E coli clonal types found in patients with suspected UTIs—being the most prevalent. Follow-up urine samples in 74 of the women showed that ST131 H30R and ST1193 were isolated nearly twice as frequently as fluoroquinolone susceptible E coli and other clonal types of fluoroquinolone-resistant E coli.

Out of 67 women who provided both a urine sample and a second fecal sample, there was a strong association between bacteriuria and fecal persistence (OR, 8.3; 95% CI, 1.5 to 22.2, P = .011).

The researchers say the superior gut persistence of the pandemic clones, and their superior capability to invade the urinary tract, could contribute to their remarkable global spread and their dominance among fluoroquinolone-resistant E coli of UTI origin.

Jul 4 Clin Infect Dis abstract