Early Response Assessment to Guide Management of Methicillin-Resistant Staphylococcus aureus Bloodstream Infections With Vancomycin Therapy

Background

A subset of vancomycin-treated patients with methicillin-resistant Staphylococcus aureus (MRSA) bloodstream infection (BSI) developed persistent positive blood cultures. Treatment eventually failed.

Methods

A retrospective study was conducted to determine whether early response on day 3 after initiation of vancomycin therapy for MRSA BSI was associated with reduced rates of persistent bacteremia, end-of-treatment failure, and infection-related mortality. Patients’ medical charts were reviewed. Susceptibility testing and molecular characterization of bacterial isolates were performed.

Results

In this elderly cohort (n = 111; median age 70 years, interquartile range: 57–80 years), early response was observed in 62% of patients and was significantly (P < 0.0001) associated with lower rates of end-of-treatment failure (19% vs 57%) and infection-related death (1% vs 29%), but not with persistent bacteremia (17% vs 29%, P = 0.23). Nearly half (46%; 46 of 100 patients) remained on vancomycin therapy for the entire treatment course; those who continued despite lack of early response had a trend toward a higher risk of death than those who were switched to alternative therapy (38% vs 10%, P = NS). Most (68%) isolates had vancomycin MIC of >1 µg/mL, whereas 10% showed heterogeneous glycopeptide-intermediate Staph aureus (hGISA) phenotype. Nearly half (47%) were typed with staphylococcal cassette chromosome mec IV or V. In a multivariate logistic regression model, lack of response at day 3 was the strongest predictor for end-of-treatment failure, after adjustment for confounders such as age, Acute Physiology And Chronic Health Evaluation II score, intensive care unit admission, vancomycin MIC >1 µg/mL, unbound trough concentration <4 to 5× MIC, and continued vancomycin therapy without change.

Conclusions

Early response assessment after initiation of vancomycin therapy appeared to be useful for considering further diagnostic workup or a switch to alternative therapy to affect a positive outcome in patients with MRSA BSI.     

2018-2020年皮肤科住院患者金黄色葡萄球菌感染状况及MRSA与MSSA耐药性分析

目的:研究我院住院患者中皮肤软组织感染者(SSTIs)金黄色葡萄球(SA)感染情况及MR-SA与MSSA耐药特点.方法:选取我院2018年1月1日至2020年12月31日入院时存在SSTIs且进行细菌培养及药敏试验的患者,分析SA及MRSA检出率、病种分布,以及MRSA与MSSA耐药性的差异.结果:共分析1455例患者...     

Extraintestinal Clostridium difficile Infections: A Single-Center Experience

ObjectivesTo evaluate the clinical burden of extraintestinal Clostridium difficile infection (CDI) seen at a single institution and to characterize the management and outcomes of these rare infections.Patients and MethodsA retrospective medical record review was conducted to identify patients with isolation of C difficile from extraintestinal sites from January 1, 2004, through December 31, 2013. Medical records were reviewed and data, including demographic characteristics, microbiology, clinical associations, management, and infection outcomes, were abstracted.ResultsOverall, 40 patients with extraintestinal CDI were identified: 25 had abdominopelvic infections, 11 had bloodstream infections, 3 had wound infections, and 1 had pulmonary infection. C difficile was isolated with other organisms in 63% of cases. A total of 85% of infections were nosocomial. Factors associated with extraintestinal CDI included surgical manipulation of the gastrointestinal tract (88%), recent antibiotic exposure (88%), malignant tumors (50%), and proton pump inhibitor use (50%). Diarrhea was present in 18 patients (45%), 12 of whom had C difficile polymerase chain reaction (PCR)–positive stool samples. All isolates tested were susceptible to metronidazole and piperacillin-tazobactam. Management included both antimicrobial therapy and guided drainage or surgical intervention in all but one patient. The infection-associated mortality rate was 25%, with death a median of 16 days (range, 1-61 days) after isolation of C difficile.ConclusionExtraintestinal CDI is uncommon and often occurs in patients with surgical manipulation of the gastrointestinal tract and well-recognized risk factors for intestinal CDI. Management of extraintestinal CDI includes both antimicrobial and surgical therapies. Extraintestinal CDI is characterized by poor outcome with high mortality.     

Is prediffusion test an alternative to improve accuracy in screening hVISA strains and to detect susceptibility to glycopeptides/lipopeptides?

The characterization of heteroresistant vancomycin-intermediate Staphylococcus aureus strains (hVISA) is even more challenging, as no routine standardized laboratory methods are available. A total of 124 S. aureus isolates recovered from inpatients attended in hospitals of Santa Catarina State, Southern Brazil, were evaluated. The MIC of vancomycin, teicoplanin, and daptomycin was determined by Etest and prediffusion tests using NeoSensitabs® tablets. All isolates were susceptible to vancomycin (MICs: 0.5–3 μg/mL) by Etest. However, according to prediffusion test, 17 isolates presented reduced susceptibility to vancomycin, and of these, 12 were confirmed as hVISA using populational analysis. Considering daptomycin, prediffusion results were in agreement with susceptibility data (MICs), as all isolates were susceptible. Considering that characterizing hVISA is challenging and that MIC determination is not adequate to characterize this phenotype, prediffusion test was a viable alternative to screening hVISA and reduced susceptibility to vancomycin. It was simple and low cost, with accuracy comparable to other well-established methods.     

丹参生品及不同炮制品的体外抗菌活性研究

目的研究丹参不同炮制品(清炒、炒炭、米炒、酒炙和醋制丹参)的体外抗菌活性。方法采用纸片扩散法研究丹参不同炮制品对金黄色葡萄球菌(SA)、耐甲氧西林的金黄色葡萄球菌(MRSA)和β-内酰胺酶阳性金黄色葡萄球菌(ESBLs)的抑制活性。结果丹参生品及不同炮制品对SA和MRSA的抑制作用略强于ESBLs,对SA的抗菌效果最强;其中炒丹参的甲醇总提取物质量浓度在50 mg/mL对SA、MRSA、ESBLs的抑菌圈直径最大且相同;对相应样品的MIC值进行比较,显示各样品体外抗菌活性大小依次为:丹参生品及炮制品的甲醇提取物>石油醚和乙酸乙酯提取物>正丁醇提取物。结论本实验证明炒丹参和酒丹参的抗菌活性明显增强,而丹参炭的抗菌活性明显减弱,但仍具有一定的抗菌活性。     

Coincidental outbreak of methicillin-resistant Staphylococcus aureus in a hematopoietic stem cell transplantation unit

BACKGROUND: Methicillin-resistant Staphylococcus aureus (MRSA) is one of the most common nosocomial pathogens among hospital-acquired infections, and immunocompromised patients are highly susceptive to infection. The molecular typing of isolated strains is a common method for tracing an outbreak of MRSA, but experience with this approach is still limited in the hematopoietic stem cell transplantation (HSCT) ward. METHODS: We experienced 6 cases of MRSA infection/colonization in our 26-bed HSCT ward during a 4-week period. This unusual outbreak strongly suggested that the same MRSA strain was involved despite strict isolation and aseptic patient care. Clarification of the transmission pattern was critical, and we applied pulsed-field gel electrophoresis (PFGE) and amplified fragment length polymorphism (AFLP) assays for evaluation. RESULTS AND CONCLUSION: In four of the six cases, the pattern of bands examined by PFGE and AFLP analyses supported the idea that direct person-to-person transmission was very unlikely and the outbreak was coincidental. This experience highlights the clinical value of molecular typing methods for the clinical epidemiological assessment of MRSA outbreak.     

Evolution, antimicrobial susceptibility and assignment to international clones of methicillin-resistant Staphylococcus aureus isolated over a 9-year period in two Spanish hospitals

Antimicrobial resistance profiles, restriction fragment length polymorphism of the coagulase gene and repetitive element sequence-based PCR were used to classify 210 methicillin-resistant Staphylococcus aureus isolates recovered between 1997 and 2005 in two hospitals in Vigo, north-west Spain. Representative isolates belonging to the epidemic clones were analysed by spa typing and multilocus sequence typing, and the staphylococcal chromosomal cassette (SCC)mec type was determined for all isolates. The New York/Japan clone (t002-ST5-II) was detected in Spain for the first time. However, the New York/Japan and the Brazilian (t037-ST239-IIIA) clones were replaced by EMRSA-16 (t018-ST36-II), which at present is the predominant clone.