Research Article: Association of bacterial genotypes and epidemiological features with treatment failure in hemodialysis patients with methicillin-resistant Staphylococcus aureus bacteremia

Date Published: June 4, 2018

Publisher: Public Library of Science

Author(s): Shang-Yi Lin, Hung-Pin Tu, Tun-Chieh Chen, Mei-Chiou Shen, Yi-Wen Chiu, Yen-Hsu Chen, Po-Liang Lu, Chih-Jung Chen.

http://doi.org/10.1371/journal.pone.0198486

Abstract

Methicillin-resistant Staphylococcus aureus (MRSA) infections in the hemodialysis (HD) population are epidemiologically classified as healthcare-associated infections. The data about the clinical impact and bacterial characteristics of hospital-onset (HO)- and community-onset (CO)-MRSA in HD patients are scarce. The current study analyzed the difference in the clinical and molecular characteristics of HO-MRSA and CO-MRSA.

We performed a retrospective review and molecular analysis of clinical isolates from 106 HD patients with MRSA bacteremia from 2009 to 2014. CA genotypes were defined as isolates carrying the SCCmec type IV or V, and HA genotypes were defined as isolates harboring SCCmec type I, II, or III.

CO-MRSA infections occurred in 76 patients, and 30 patients had HO-MRSA infections. There was no significant difference in the treatment failure rates between patients with CO-MRSA infections and those with HO-MRSA infections. CA genotypes were associated with less treatment failure (odds ratio [OR]: 0.18; 95% confidence interval [95% CI], 0.07–0.49; p = 0.001). For isolates with a vancomycin minimum inhibitory concentration (MIC) < 1.5 mg/L, the multivariate analysis revealed that HA genotypes and cuffed tunneled catheter use were associated with treatment failure. For isolates with a vancomycin MIC ≥1.5 mg/L, the only risk factor for treatment failure was a higher Pitt score (OR: 1.76; 95% CI, 1.02–3.05; p = 0.043). CA genotypes, but not the epidemiological classification of CO-MRSA, impacted the clinical outcome of MRSA bacteremia in the HD population.

Partial Text

Although there has been a decreasing trend in the incidence of methicillin-resistant Staphylococcus aureus (MRSA) infections in the past decade [1], MRSA remains a major threat to patients all over the world. The hemodialysis (HD) population has a high risk for invasive MRSA infections that is more than 100-fold higher than the incidence rate of the general population (45.2/1000 vs. 0.2–0.4/1000) [2]. The incidence of invasive MRSA infections among dialysis patients decreased by 7.3% annually during 2005–2011 in the USA [3]. However, a rate of 19.9% for healthcare-associated invasive MRSA infections was identified among dialysis patients in the USA in 2014 [4]. MRSA infections in HD patients are associated with long hospitalizations, high costs and mortality [5]. Therefore, the impact of MRSA infections in the HD population remains significant.

In this study, we identified an increasing trend of CO-MRSA in the HD population with MRSA bacteremia in a Taiwanese medical center during 2009–2014. Increasingly, MRSA bacteremia cases in the HD population in Taiwan are due to CA-genotypes, indicating the successful spread of CA genotypes in the HD population. This finding that CA- and HA-MRSA strains infected HD patients in healthcare facilities is similar to the situation of the co-existence of CA and HA genotypes in hospital settings [1, 22, 23]. Our results revealed that the CA genotype is a better predictor of clinical outcome than the epidemiologic classification of CO- or HO-infections. This strain-specific virulence factor effect was an independent risk factor for treatment outcomes in a subgroup analysis for patients with a vancomycin MIC < 1.5 mg/L, but this effect was attenuated with a vancomycin MIC ≥1.5 mg/L.   Source: http://doi.org/10.1371/journal.pone.0198486

 

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