Complexity of patients with or without infectious disease consultation in tertiary-care hospitals in Germany.

PURPOSE: Patients seen by infectious disease (ID) specialists are more complex compared to patients treated by other subspecialities according to Tonelli et al. (2018). However, larger studies on the complexity of patients related to the involvement of ID consultation services are missing. METHODS: Data of patients being treated in 2015 and 2019 in four different German university hospitals was retrospectively collected. Data were collected from the hospitals' software system and included whether the patients received an ID consultation as well as patient clinical complexity level (PCCL), case mix index (CMI) and length of stay (LOS) as a measurement for the patients' complexity. Furthermore, a comparison of patients with distinct infectious diseases treated with or without an ID consultation was initiated. RESULTS: In total, 215.915 patients were included in the study, 3% (n = 6311) of those were seen by an ID consultant. Patients receiving ID consultations had a significantly (p < 0.05) higher PCCL (median 4 vs. 0), CMI (median 3,8 vs. 1,1) and deviation of the expected mean LOS (median 7 days vs. 0 days) than patients in the control group. No differences among hospitals or between years were observed. Comparing patients with distinct infectious diseases treated with or without an ID consultation, the differences were confirmed throughout the groups. CONCLUSION: Patients receiving ID consultations are highly complex, frequently need further treatment after discharge and have a high economic impact. Thus, ID specialists should be clinically trained in a broad spectrum of diseases and treating these complex patients should be sufficiently remunerated.

Vertebral osteomyelitis in patients with Staphylococcus aureus bloodstream infection: Evaluation of risk factors for treatment failure.

OBJECTIVES: Staphylococcus aureus is the most common cause of pyogenic vertebral osteomyelitis (VO). Studies indicate that S. aureus VO results in poor outcome. We aimed to investigate risk factors for treatment failure in patients with Staphylococcus aureus bloodstream infection (SAB) and VO. METHODS: We conducted a post hoc-analysis of data from a German bi-center prospective SAB cohort (2006-2014). Patients were followed-up for one year. Primary outcome was treatment failure defined as relapse and/or death within one year. RESULTS: A total of 1069 patients with SAB were analyzed, with 92 VO patients. In addition to antibiotic treatment, surgery was performed in 60/92 patients. Treatment failed in 44/92 patients (death, n = 42; relapse, n = 2). Multivariable analysis revealed higher age (HR 1.04 [per year], 95%CI 1.01-1.07), Charlson comorbidity index (HR 1.20, 95%CI 1.06-1.36), presence of neurologic deficits (HR 2.53, 95%CI 1.15-5.53) and local abscess formation (HR 3.35, 95%CI 1.39-8.04) as independent risk factors for treatment failure. In contrast, surgery seemed to be associated with a favourable outcome (HR 0.45 (95%CI 0.20-0.997)). CONCLUSION: SAB patients with VO exhibit a high treatment failure rate. Red flags are older age, comorbidities, neurologic deficits and local abscess formation. Whether these patients benefit from intensified treatment (e.g. radical surgery, prolongation of antibiotics) should be investigated further.

Burden of bacterial bloodstream infection-a brief update on epidemiology and significance of multidrug-resistant pathogens.

BACKGROUND: Bloodstream infections comprise a wide variety of pathogens and clinical syndromes with considerable overlap with similar syndromes of non-bacteraemic infections and diverse risk factors, therapeutic implications and outcomes. Yet, this heterogeneous 'entity' has the advantage to be pathogen-defined compared with the broad and even more heterogeneous entity 'sepsis', and so has become helpful for clinicians and epidemiologists for research and surveillance purposes. The increasing availability of population-based and large multicentre well-defined cohort studies should allow us to assess with much confidence and in detail its burden, the significance of antimicrobial resistance, and areas of uncertainty regarding further epidemiological evolution and optimized treatment regimens. AIM: To review key aspects of bloodstream infection epidemiology and burden, and summarize recent news and questions concerning critical developments. SOURCES: Peer-reviewed articles based on the search terms 'bloodstream infection' and 'bacteremia' combined with the terms 'epidemiology' and 'burden'. The emphasis was on new information from studies in adult patients and on the added burden due to pathogen resistance to first- and second-line antimicrobial agents. CONTENT: Topics covered include recent developments in the epidemiology of bloodstream infection due to key pathogens and published information about the relevance of resistance for patient outcomes. IMPLICATIONS: Despite the availability of population-based studies and an increasing number of large well-defined multicentre cohort studies, more surveillance and systematic data on bloodstream infection epidemiology at regional level and in resource-limited settings may be needed to better design new methods for prevention and define the need for and further develop optimized therapeutic strategies.

Essentials in the management of S. aureus bloodstream infection.

AIMS: Staphylococcus aureus bloodstream infection is one of the most common serious bacterial infections worldwide. It represents a heterogenous clinical entity with a high risk of metastatic complications and a high in-hospital mortality ranging between 20 and 30%. The outcome can be improved by optimised diagnostic and therapeutic management. Thus, our minireview should provide important and often missed pieces of information in the management of S. aureus bloodstream infection. METHODS: We describe the essentials in the management of S. aureus bloodstream infection. RESULTS: Five essentials were identified: 1) S. aureus bacteremia should always be considered clinically significant. 2) Length of bacteremia and fever is relevant for diagnostic workup, duration of therapy and prognosis. 3) Prompt identification and eradication of portal of entry and infective/metastatic foci are essential. 4) Infective endocarditis should be excluded. 5) Intravenous treatment for at least two weeks up to 4-6 weeks with antistaphylococcal penicillins for MSSA and vancomycin or daptomycin for MRSA bloodstream infection is indicated. CONCLUSION: Further efforts should be undertaken to increase the adherence to the essentials in the management of S. aureus bloodstream infection.

Treatment with proton pump inhibitors is associated with increased mortality in patients with pyogenic liver abscess.

BACKGROUND: Proton pump inhibitors (PPI) are often used in patients with gastro-esophageal reflux and peptic ulcer disease. A higher risk for infectious diseases and for pyogenic liver abscess has been reported in patients with prolonged PPI intake. Although many patients have ongoing PPI treatment after diagnosis of liver abscess, there are no data available that focus on the prognostic impact of PPI treatment in these patients. AIM: To analyse the effect of PPI treatment on mortality in patients with pyogenic liver abscesses. METHODS: Between January 2005 and March 2017, one hundred and eighty-one patients with pyogenic liver abscess were retrospectively included in this analysis. Medical records including PPI treatment, microbiological and imaging data were reviewed. The primary endpoint was index mortality and predictive factors were analysed using uni- and multivariate logistic regression models. RESULTS: One hundred patients with pyogenic liver abscess (55.2%) were treated with PPI compared to 81 patients (44.8%) without PPI treatment. In both patient cohorts, enterococcus spp. and streptococcus of the anginous group were the most common pathogens identified. Patients with PPI treatment had significantly higher index mortality compared to patients without PPI treatment (30.0% vs 11.1%, P = 0.003). After adjusting for comorbidities PPI remained an independent predictive factor with an OR of 2.56 (1.01-6.46, P = 0.036). CONCLUSIONS: PPI treatment is associated with higher index mortality in patients with pyogenic liver abscess. Therefore, critical evaluation of the indication for PPI treatment is particularly important in patients at high risk for pyogenic liver abscess.

Combination antimicrobial therapy in patients with Staphylococcus aureus bacteraemia-a post hoc analysis in 964 prospectively evaluated patients.

OBJECTIVES: The evidence for using combination antimicrobial therapy (CoRx) in Staphylococcus aureus bacteraemia (SAB) is limited. We aimed to investigate whether CoRx is associated with higher survival or lower SAB-related late complications. METHODS: We performed a post hoc analysis of a prospective SAB cohort study. CoRx was defined as a cell wall-active antistaphylococcal agent plus either rifampicin, a fluoroquinolone, fosfomycin or an aminoglycoside. To adjust for survivor bias multivariable Cox models that included CoRx as a time-dependent covariable were calculated. RESULTS: Of 964 evaluable patients, 512 (53%) received CoRx, most of them (301/512, 59%) rifampicin-containing CoRx. All-cause mortality after 30 and 90 days was similar for the two groups, although the patients in the CoRx group had more often endocarditis, deep-seated or disseminated infections and severe sepsis/septic shock. For the entire cohort, only age, comorbidity and severe sepsis/septic shock were associated with a higher mortality and infectious disease consultation, but not CoRx with a lower mortality. However, in the subgroup of patients with implanted foreign bodies or devices CoRx was independently associated with a lower mortality at 30 days (hazard ratio 0.6, 95% confidence interval 0.3-1.1) and at 90 days (hazard ratio 0.6, 95% confidence interval 0.4-0.9). SAB-related late complications in this subgroup occurred in 15 (10.6%) of 142 patients in the monotherapy group vs. nine (4.5%) of 202 patients in the CoRx group (p 0.03). CONCLUSIONS: In a setting of optimized management of adult patients with SAB secured by infectious disease consultations, this observational study could not prove CoRx to be independently associated with improved survival or reduced late complications in the entire cohort. However, administration of CoRx may be associated with lower mortality and fewer SAB-related late complications in the subgroup of patients with implanted foreign bodies or devices. Prospective randomized trials should be performed to prove this benefit.

α-Defensins partially protect human neutrophils against Panton-Valentine leukocidin produced by Staphylococcus aureus.

UNLABELLED: α-Defensins produced by neutrophils are important effector molecules of the innate immune system. In addition to their microbicidal effects, α-defensins have the ability to neutralize bacterial toxins. Panton-Valentine leukocidin (PVL) is the hallmark of community-acquired methicillin-resistant Staphylococcus aureus. Staphylococcus aureus that produce PVL are responsible for severe diseases, including necrotizing pneumonia. Polymorphonuclear neutrophils (PMNs) are the target cells of PVL action. The goal of this study was to elucidate the effect of a group of α-defensins known as the human neutrophil peptides (HNPs) on the interactions between LukS-PV and LukF-PV, which compose PVL, and human PMNs. We observed that HNPs bound to both subunits of PVL and significantly decreased PVL pore formation in PMNs, with a maximum inhibition of 27%. When various HNP molecules were tested individually under the same conditions, we observed that HNP3, but not HNP1 or 2, decreased pore formation. Similarly, HNP3 significantly decreased PVL-induced PMN lysis, with a maximum inhibition of 31%. Interestingly, HNPs did not affect LukS-PV LukF-PV oligomerization, LukS-PV LukF-PV binding to PMNs or calcium influx induced by PVL in PMNs. Our results suggest that HNP3 partially protects neutrophils against PVL by interfering with the conformational changes of PVL required to form a functional pore. SIGNIFICANCE AND IMPACT OF THE STUDY: Panton-Valentine leukocidin (PVL) is a pore-forming toxin produced by Staphylococcus aureus, responsible for neutrophil damage and key player of severe staphylococcal diseases. Antimicrobial peptides produced by neutrophils (HNP1-3) neutralize several other bacterial cytotoxins. We examined the impact of human neutrophil peptides (HNPs) on PVL cytotoxicity against human neutrophils and we found that HNPs bind to both LukS and LukF components of PVL, thereby inhibiting pore formation and neutrophil lysis. Our results suggest that HNP3 may impair PVL conformational changes required to form a functional pore and provide insight into the pathogenesis of PVL-related staphylococcal infection, with potential impact on the disease outcome.

Expression of the sweat-derived innate defence antimicrobial peptide dermcidin is not impaired in Staphylococcus aureus colonization or recurrent skin infections.

Antimicrobial peptides are an integral part of innate immunity, and contribute to the protection of human skin from Staphylococcus aureus colonization and infection. We sought to investigate whether the expression of the eccrine sweat-derived staphylocidal antimicrobial peptide dermcidin might influence S. aureus colonization or recurrent skin and soft-tissue infections (SSTIs). Eccrine sweat was collected from 18 patients with recurrent S. aureus SSTIs, 28 patients who were intermittent or permanent S. aureus carriers, and 32 noncarriers. Expression and proteolytic degradation of dermcidin was investigated using ELISA and surface-enhanced laser desorption ionization time-of-flight mass spectrometry (SELDI-TOF-MS). We found no significant differences in the overall amount or the proteolytic degradation pattern of dermcidin-derived peptides between healthy noncarriers, intermittent and permanent carriers, and patients with recurrent S. aureus SSTIs. S. aureus colonization or recurrent SSTIs do not seem to be associated with diminished dermcidin expression in eccrine sweat.

Delay in the administration of appropriate antimicrobial therapy in Staphylococcus aureus bloodstream infection: a prospective multicenter hospital-based cohort study.

OBJECTIVES: Early broad-spectrum antimicrobial treatment reduces mortality in patients with septic shock. In a multicenter, prospective observational study, we explored whether delayed appropriate antimicrobial therapy (AAT) influences outcome in Staphylococcus aureus bloodstream infection (SAB). METHODS: Two hundred and fifty-six patients with SAB from ten German study centers were enrolled and followed for 3 months. Predisposing factors, clinical features, diagnostic procedures, antimicrobial therapy, and outcome were recorded. The appropriateness of antimicrobial therapy was judged by a trained physician based on in vitro activity, dosage, and duration of therapy. Therapy was considered to be delayed when more than 24 h elapsed between the first positive blood culture and the start of appropriate therapy. The association of delayed therapy with overall mortality and SAB-related events (i.e., attributable mortality or late SAB-related complications) was assessed by crosstabulation and propensity score-based logistic regression. RESULTS: One hundred and sixty-eight patients received AAT during their hospital stay, of whom 42 (25%) received delayed AAT. The overall mortality and the occurrence of severe sepsis or septic shock were lower in patients with delayed AAT, pointing towards confounding by indication. Adjusted 90-day mortality (adjusted odds ratio [OR] 0.91, 95% confidence interval [CI] [0.39-2.13], p 0.82) and SAB-related events (adjusted OR 1.46, 95% CI [0.47-4.51], p 0.52) also failed to show a significant impact of delayed AAT on outcome. CONCLUSION: In patients with SAB, early AAT may not improve survival. However, confounding by indication is a major challenge when analyzing and interpreting observational studies on the impact of delayed AAT.

Naturally processed dermcidin-derived peptides do not permeabilize bacterial membranes and kill microorganisms irrespective of their charge.

Dermcidin (DCD) is a recently described antimicrobial peptide, which is constitutively expressed in eccrine sweat glands and transported via sweat to the epidermal surface. By postsecretory proteolytic processing in sweat the dermcidin protein gives rise to several truncated DCD peptides which differ in length and net charge. In order to understand the mechanism of antimicrobial activity, we analyzed the spectrum of activity of several naturally processed dermcidin-derived peptides, the secondary structure in different solvents, and the ability of these peptides to interact with or permeabilize the bacterial membrane. Interestingly, although all naturally processed DCD peptides can adopt an alpha-helical conformation in solvents, they have a diverse and partially overlapping spectrum of activity against gram-positive and gram-negative bacteria. This indicates that the net charge and the secondary structure of the peptides are not important for the toxic activity. Furthermore, using carboxyfluorescein-loaded liposomes, membrane permeability studies and electron microscopy we investigated whether DCD peptides are able to permeabilize bacterial membranes. The data convincingly show that irrespective of charge the different DCD peptides are not able to permeabilize bacterial membranes. However, bacterial mutants lacking specific cell envelope modifications exhibited different susceptibilities to killing by DCD peptides than wild-type bacterial strains. Finally, immunoelectron microscopy studies indicated that DCD peptides are able to bind to the bacterial surface; however, signs of membrane perturbation were not observed. These studies indicate that DCD peptides do not exert their activity by permeabilizing bacterial membranes.

Dermcidin is constitutively produced by eccrine sweat glands and is not induced in epidermal cells under inflammatory skin conditions.

BACKGROUND: Antimicrobial peptides (AMPs) are important effector molecules of innate immunity, protecting epithelial surfaces of multicellular organisms. In human skin two classes of AMPs-the beta-defensins and the cathelicidins-are produced by keratinocytes primarily under inflammatory conditions. In contrast, dermcidin (DCD), a recently discovered AMP with broad-spectrum activity, is expressed in eccrine sweat glands and transported via sweat to the epidermal surface. OBJECTIVES: To investigate whether DCD expression is induced under inflammatory conditions in epidermal keratinocytes. METHODS: Lesional skin of the inflammatory skin diseases atopic dermatitis, psoriasis and lichen planus was analysed by immunohistochemistry using a polyclonal anti-DCD antiserum. We also examined whether DCD RNA expression is induced in cultured human keratinocytes, fibroblasts, melanocytes and melanoma cells. RESULTS: Whereas DCD was constitutively expressed in eccrine sweat glands of all skin biopsies, we found that, independent of the type of the inflammatory skin lesion, DCD protein expression was not induced in human epidermal keratinocytes. In contrast, beta-defensin 2 was expressed in epidermal keratinocytes of inflammatory human skin, but not in keratinocytes of healthy human skin. Upon stimulation of the cultured cells with 12-O-tetradecanoyl-phorbol-13-acetate, tumour necrosis factor-alpha, lipopolysaccharide or H2O2, DCD mRNA expression was not detected in primary keratinocytes, fibroblasts and melanocytes, but was detected in MeWo and SKMEL28 melanoma cells. CONCLUSIONS: These results indicate that, unlike human cathelicidins and beta-defensins which are inducible peptides that primarily function in response to injury and inflammation, DCD is exclusively part of the constitutive innate defence of human skin. By modulating surface colonization, DCD may help to prevent local and systemic invasion of pathogens.