Gender affects prognosis of methicillin-resistant Staphylococcus aureus bacteremia differently depending on the severity of underlying disease

Epidemiological profile and antimicrobial resistance trends of Staphylococcus aureus in Chinese pediatric intensive care units from 2016 to 2022: a multi-center retrospective study

OBJECTIVE

This study aimed to analyze the profiles and evolution of Staphylococcus aureus in the pediatric intensive care units (PICUs) of 17 hospitals in China from 2016 to 2022.

METHODS

Susceptibility testing was performed to bacterial strains with a uniform monitoring protocol, which was provided by the US Clinical and Laboratory Standards Institute (CLSI) and used by the China Antimicrobial Surveillance Network (CHINET). The results were interpreted in accordance with the performance standards for antimicrobial susceptibility testing issued by the US Clinical and Laboratory Standards Institute.

RESULTS

Twenty-six thousand six hundred thirteen bacterial strains were isolated from 17 PICUs in China from 2016 to 2022, 3,147 of which were Staphylococcus aureus, ranking second among etiological agents of infections from PICUs. In 2022, Staphylococcus aureus had the highest detection rate, being 36.19%. And in 2021, MRSA had the highest detection rate, being 10.35% in Staphylococcus aureus. There were statistically significant differences in the annual detection rate of gram-positive bacteria, Staphylococcus aureus and MRSA between the years from 2016 to 2022 (P < 0.05). More males were found with Staphylococcus aureus or methicillin-resistant Staphylococcus aureus, but there were no statistical differences in gender distribution between any two years (P < 0.05). The top 3 highest detection rate of Staphylococcus aureus in age groups were infants (1244, 39.7%), toddlers (741, 23.7%), and children at school age and older (731, 23.4%). For MRSA, The top 3 in age groups were infants (91, 38.9%), children at school age and older (87, 29.1%), and toddlers (48, 20.5%). The detection rate of Staphylococcus aureus was statistically different in the distribution of age stratification (P < 0.05). There was no statistically significant difference in these two aspects of MRSA (P > 0.05). The top 3 highest detection rate of Staphylococcus aureus in infected sites were the lower respiratory tract (2,552, 81.7%), bloodstream (217, 6.5%), and skin wounds (110, 3.9%). For MRSA, The top 3 in infected sites were the lower respiratory tract (156, 77.9%), skin wounds (47, 8.8%), and bloodstream (15, 6.6%). The detection rate of Staphylococcus aureus and MRSA was statistically different in the distribution of infected sites (P < 0.05). All the strains of Staphylococcus aureus were sensitive to tigecycline, nitrofurantoin, vancomycin, and linezolid. The resistant rate of Staphylococcus aureus, to penicillin G was as high as 87.5% at least, to erythromycin was as high as 51.8% at least, to benzocillin was as high as 38.0% at least, to cefoxitin was as high as 35.5% at least, and to clindamycin was as high as 32.7% at least. All the strains of MRSA were sensitive to vancomycin, linezolid, quinupristin/dalfopristin, and tigecycline. Of these 234 strains of MRSA, 179 (76.5%) were resistant to erythromycin, 116 (49.6%) to clindamycin, 39 (16.7%) to tetracycline, 29 (12.4%) to levofloxacin, 27 (11.5%) to ciprofloxacin, 27 (11.5%) to moxifloxacin, 14 (6.0%) to TMP-SMX, eight (3.4%) to rifampicin, and six (2.6%) to gentamicin.

CONCLUSIONS

Staphylococcus aureus is the most common gram-positive bacterium in PICUs. Infants are most likely to be infected by Staphylococcus aureus and methicillin-resistant Staphylococcus aureus. And the lower respiratory tract is the most common infected site of Staphylococcus aureus. Staphylococcus aureus has a high resistant rates to commonly used antimicriobials in pediatrics, but no strains resistant to vancomycin and/or linezolid were found. When considering Staphylococcus aureus infection clinically, it is necessary to select antimicrobials reasonably based on the patient's age, infected site and local epidemiological characteristics.

Female Sex and Mortality in Patients with Staphylococcus aureus Bacteremia: A Systematic Review and Meta-analysis

Importance

Staphylococcus aureus is the leading cause of death due to bacterial bloodstream infection. Female sex has been identified as a risk factor for mortality in S aureus bacteremia (SAB) in some studies, but not in others.

Objective

To determine whether female sex is associated with increased mortality risk in SAB.

Data Sources

MEDLINE, Embase, and Web of Science were searched from inception to April 26, 2023.

Study Selection

Included studies met the following criteria: (1) randomized or observational studies evaluating adults with SAB, (2) included 200 or more patients, (3) reported mortality at or before 90 days following SAB, and (4) reported mortality stratified by sex. Studies on specific subpopulations (eg, dialysis, intensive care units, cancer patients) and studies that included patients with bacteremia by various microorganisms that did not report SAB-specific data were excluded.

Data Extraction and Synthesis

Data extraction and quality assessment were performed by 1 reviewer and verified by a second reviewer. Risk of bias and quality were assessed with the Newcastle-Ottawa Quality Assessment Scale. Mortality data were combined as odds ratios (ORs).

Main Outcome and Measures

Mortality at or before 90-day following SAB, stratified by sex.

Results

From 5339 studies retrieved, 89 were included (132 582 patients; 50 258 female [37.9%], 82 324 male [62.1%]). Unadjusted mortality data were available from 81 studies (109 828 patients) and showed increased mortality in female patients compared with male patients (pooled OR, 1.12; 95% CI, 1.06-1.18). Adjusted mortality data accounting for additional patient characteristics and treatment variables were available from 32 studies (95 469 patients) and revealed a similarly increased mortality risk in female relative to male patients (pooled adjusted OR, 1.18; 95% CI, 1.11-1.27). No evidence of publication bias was encountered.

Conclusions and Relevance

In this systematic review and meta-analysis, female patients with SAB had higher mortality risk than males in both unadjusted and adjusted analyses. Further research is needed to study the potential underlying mechanisms.

The association of female sex with management and mortality in patients with Staphylococcus aureus bacteraemia

OBJECTIVES

The association of biological female sex with outcome in patients with Staphylococcus aureus bacteraemia remains unresolved. The aim of this study was to determine the independent association of female sex with management and mortality in patients with S. aureus bacteraemia.

METHODS

This is a post hoc analysis of prospectively collected data from the S. aureus Bacteraemia Group Prospective Cohort Study. Adult patients with monomicrobial S. aureus bacteraemia at Duke University Medical Center were enrolled from 1994 to 2020. Univariable and multivariable Cox regression analyses were performed to assess differences in management and mortality between females and males.

RESULTS

Among 3384 patients with S. aureus bacteraemia, 1431 (42%) were women. Women were, as compared with men, more often Black (581/1431 [41%] vs. 620/1953 [32%], p < 0.001), haemodialysis dependent (309/1424 [22%] vs. 334/1940 [17%], p 0.001) and more likely to be infected with methicillin-resistant S. aureus (MRSA) (697/1410 [49%] MRSA in women vs. 840/1925 [44%] MRSA in men, p 0.001). Women received shorter durations of antimicrobial treatment (median 24 [interquartile range 14-42] vs. 28 [interquartile range 14-45] days, p 0.005), and were less likely to undergo transesophageal echocardiography as compared with men (495/1430 [35%] vs. 802/1952 [41%], p < 0.001). Despite these differences, female sex was not associated with 90-day mortality in either univariable (388/1431 [27%] in women vs. 491/1953 [25%] in men, p 0.204) or multivariable analysis (adjusted hazard ratio for women 0.98 [95% CI, 0.85-1.13]).

DISCUSSION

Despite significant differences in patient characteristics, disease characteristics, and management, women and men with S. aureus bacteraemia have a similar mortality risk.

What Is the Optimal Follow-up Length for Mortality in Staphylococcus aureus Bacteremia? Observations From a Systematic Review of Attributable Mortality

Background

Deaths following Staphylococcus aureus bacteremia (SAB) may be related or unrelated to the infection. In SAB therapeutics research, the length of follow-up should be optimized to capture most attributable deaths and minimize nonattributable deaths. We performed a secondary analysis of a systematic review to describe attributable mortality in SAB over time.

Methods

We systematically searched Medline, Embase, and Cochrane Database of Systematic Reviews from 1 January 1991 to 7 May 2021 for human observational studies of SAB. To be included in this secondary analysis, the study must have reported attributable mortality. Two reviewers extracted study data and assessed risk of bias independently. Pooling of study estimates was not performed due to heterogeneity in the definition of attributable deaths.

Results

Twenty-four observational cohort studies were included. The median proportion of all-cause deaths that were attributable to SAB was 77% (interquartile range [IQR], 72%–89%) at 1 month and 62% (IQR, 58%–75%) at 3 months. At 1 year, this proportion was 57% in 1 study. In 2 studies that described the rate of increase in mortality over time, 2-week follow-up captured 68 of 79 (86%) and 48 of 57 (84%) attributable deaths that occurred by 3 months. By comparison, 1-month follow-up captured 54 of 57 (95%) and 56 of 60 (93%) attributable deaths that occurred by 3 months in 2 studies.

Conclusions

The proportion of deaths that are attributable to SAB decreases as follow-up lengthens. Follow-up duration between 1 and 3 months seems optimal if evaluating processes of care that impact SAB mortality.

Clinical Trials Registration

PROSPERO CRD42021253891.

Higher Risk for All-cause Mortality of Staphylococcus aureus Bacteremia in Patients with Non-Dialysis Dependent Chronic Kidney Disease

Background

Staphylococcus aureus bacteremia (SAB) is a common and serious infection with a high mortality. Patients with chronic kidney disease (CKD) are vulnerable to SAB, but there have been few studies performed on the clinical characteristics and outcomes of SAB in CKD patients stratified by dialysis. We aimed to estimate the all-cause mortality and identify its predictors in patients with CKD.

Materials and Methods

We conducted a retrospective study on the patients with SAB hospitalized in a tertiary care center in Korea between March 2014 and December 2018. Kaplan-Meier analysis was performed to compare all-cause mortality following SAB among patients with non-dialysis dependent CKD (ND-CKD), those receiving dialysis, and those without CKD (non-CKD). The predictors of mortality among CKD patients were analyzed by Cox proportional hazards regression.

Results

As a total, 278 SAB of 43 ND-CKD (31 males), 58 dialysis (39 males), and 177 non-CKD (112 males) patients were included. The 30-day mortality was 39.5% in ND-CKD, 27.6% in dialysis, and 7.9% in non-CKD patients. The hazard ratio of all-cause mortality following SAB in ND-CKD was 2.335 (95% confidence interval, 1.203 – 4.531; P = 0.003), compared to non-CKD patients. For methicillin-resistant S. aureus bacteremia (MRSAB), the hazard ratio of all-cause mortality in ND-CKD was 2.628 (95% CI, 1.074 – 6.435; P = 0.011), compared to dialysis patients. Appropriate antibiotics <48 h was independently related to improved survival following SAB among ND-CKD (adjusted HR, 0.304; 95% CI, 0,108 – 0.857; P = 0.024) and dialysis (adjusted HR, 0.323; 95% CI, 0,116 – 0.897; P = 0.030) patients.

Conclusion

ND-CKD patients demonstrated poor outcome following SAB and administration of appropriate antibiotics within 48 h could reduce the risk for mortality.

A Prospective Cohort Study of Durations of Staphylococcus aureus Bacteremia According to Different Phenotypes and a New Concept of Persistent Bacteremia

The purpose of this study was to describe and compare the duration of Staphylococcus aureus bacteremia (SAB) according to methicillin resistance and the primary foci of infection. We also aimed to newly define persistent SAB considering these results. Nonduplicated episodes of SAB in patients aged ≥15 years from 14 hospitals in the Republic of Korea were analyzed between January 2009 and February 2018. The duration of SAB was defined as the number of days from the time of administration of an antibiotic to which the isolate was susceptible after the onset of SAB to the last day of a positive blood culture for S. aureus SAB durations were described and compared based on methicillin resistance and the primary foci of infection. Cases in the top quartile for the duration of bacteremia in the respective clinical context were classified as newly defined persistent SAB, and its association with in-hospital mortality was evaluated. A total of 1,917 cases were analyzed. The duration of SAB was longer in patients with methicillin-resistant SAB (MRSAB; n = 995) than in patients with methicillin-susceptible SAB (MSSAB; n = 922) (median duration, 1 day [interquartile range, 1 to 3 days] for MSSAB and 1 day [interquartile range, 0 to 5 days] for MRSAB; P < 0.001). The duration of bacteremia was longer in patients with endocarditis and bone and joint, endovascular, and surgical site infections and was shorter in patients with skin and soft tissue infections. Newly defined persistent SAB was independently associated with in-hospital mortality (adjusted odds ratio, 1.97; 95% confidence interval, 1.54 to 2.53; P < 0.001). The durations of SAB were dependent on methicillin resistance and the primary foci of infection, and considering these contexts, persistent SAB was significantly associated with in-hospital mortality.