Oral rifampin for eradication of Staphylococcus aureus carriage from healthy and sick populations: a systematic review of the evidence from comparative trials

Rifampicin treatment of canine multidrug-resistant meticillin-resistant staphylococcal pyoderma: A retrospective study of 51 cases

BACKGROUND

Rifampicin (RFP) is a potential treatment for canine multidrug-resistant (MDR) meticillin-resistant staphylococci (MRS), yet the use of lower doses based on recent MIC data has not been evaluated in vivo.

HYPOTHESIS/OBJECTIVES

To provide information on the efficacy and safety of low-dose range RFP (≤6 mg/kg/day) for the treatment of canine MDR MRS pyoderma.

ANIMALS

Fifty-one client-owned dogs.

MATERIALS AND METHODS

Retrospective review of dogs medical records. Dogs were from 11 US dermatology referral practices and had oral RFP at ≤6 mg/kg/day. Data evaluated included response to treatment, adverse events, and serum changes in alanine aminotransferase (ALT) and alkaline phosphatase (ALP).

RESULTS

Complete resolution of pyoderma occurred in 39 of 51 dogs (76.5%). Topical antimicrobials were used concurrently in most cases (47 of 51; 92.2%). ALP elevation >1.5-fold of baseline or the high end of the reference range occurred in nine of 37 (24.3%) dogs, while ALT elevation above baseline and the high end of the reference range occurred in two of 36 (5.6%). Only six of 51 (11.8%) had clinical adverse events during treatment; five of six (83.3%) were mild reactions consisting of lethargy and gastrointestinal signs, while one dog had a possible cutaneous adverse drug reaction. Of those that experienced clinical adverse events, four of six (66.7%) did not have concurrent increased liver enzyme activity, while two of six (33.3%) had elevations in ALP alone.

CONCLUSIONS AND CLINICAL RELEVANCE

Low-dose RFP (≤6 mg/kg/day) appears to be a relatively safe and effective single-agent systemic antibiotic in combination with topical antimicrobials for canine MDR MRS pyoderma.

Molecular Characterization of Rifampicin-Resistant Staphylococcus aureus Isolates from Retail Foods in China

This study investigated the molecular characteristics of rifampin-resistant (RIF-R) Staphylococcus aureus isolates recovered from 4300 retail food samples covering most provincial capitals in China, from 2011 to 2016. Of the 1463 S. aureus enrolled, 149 isolates (142 MSSA and 7 MRSA) were identified as rifampicin-resistant, including 20 high-level (MICs ≥ 8 μg/mL) and 129 low-level (MICs between 2 and 4 μg/mL) rifampicin-resistant strains. Most of the RIF-R S. aureus isolates were resistant to more than three antibiotics. The mutations in the rifampicin resistance-determining region of the rpoB gene were studied in all RIF-R strains. All of the strains presented the mutational change 481 His/Asn and five isolates presented an additional mutation, including 477 Asp/Tyr, 527 Ile/Met, and 466 Leu/Ser, respectively. Thirteen STs and twenty-one spa types were represented, in which five MRSA showed non-type SCCmec and the remaining MRSA belonged to SCCmec type IV-where, ST1-t127 was the predominant type from all of the isolates, while ST398-t034 was the predominant type for the MRSA isolates. In this study, we found that the food-related RIF-R S. aureus may have a unique genetic background selection. However, the scenario regarding the presence of RIF-R S. aureus, especially MRSA, in retail food in China is not favorable and warrants public attention.

Meticillin-resistant Staphylococcus aureus transmission among healthcare workers, patients and the environment in a large acute hospital under non-outbreak conditions investigated using whole-genome sequencing

BACKGROUND

The role of meticillin-resistant Staphylococcus aureus (MRSA) colonization of healthcare workers (HCWs), patients and the hospital environment in MRSA transmission in non-outbreak settings is poorly understood.

AIMS

To investigate transmission events (TEs) involving HCWs, patients and the environment under non-outbreak conditions in a hospital with a history of endemic MRSA using whole-genome sequencing (WGS).

METHODS

HCW (N = 326) and patient (N = 388) volunteers on nine wards were tested for nasal and oral MRSA colonization over two years. Near-patient environment (N = 1164), high-frequency touch sites (N = 810) and air (N = 445) samples were screened for MRSA. Representative MRSA and clinical isolates were analysed by WGS and core-genome multi-locus sequence typing (cgMLST). Closely related isolates (≤24 allelic differences) were segregated into related isolated groups (RIGs).

FINDINGS

In total, 155 MRSA were recovered: clinical isolates (N = 41), HCWs (N = 22), patients (N = 37), environmental isolates (N = 55). Nine clonal complexes (CCs) were identified among 110/155 MRSA sequenced with 77/110 assigned to CC22. Seventy-nine MRSA segregated into 17 RIGs. Numerous potential TEs were associated with CC22-MRSA (RIGs 1-15), CC45-MRSA (RIG-16) and CC8-MRSA (RIG-17). RIG-1, (the largest RIG) contained 24 ST22-MRSA-IVh from six HCWs, six patients, four clinical and eight environmental samples recovered over 17 months involving 7/9 wards. TEs involving HCW-to-patient, HCW-to-HCW, patient-to-patient and environmental contamination by HCW/patient isolates were evident. HCW, patient, clinical and environmental isolates were identified in four, nine, seven and 13 RIGs, respectively, with 12/13 of these containing isolates closely related to HCW and/or patient isolates.

CONCLUSIONS

WGS detected numerous potential hospital MRSA TEs involving HCWs, patients and the environment under non-outbreak conditions.

Genomic and in vitro pharmacodynamic analysis of rifampicin resistance in multidrug-resistant canine Staphylococcus pseudintermedius isolates

BACKGROUND

Antimicrobial resistance is a growing concern in canine Staphylococcus pseudintermedius dermatitis. Treatment with rifampicin (RFP) is considered only in meticillin-resistant and multidrug-resistant S. pseudintermedius (MDR-MRSP).

HYPOTHESIS/OBJECTIVES

To determine an optimal RFP dosing for MDR-MRSP treatment without induction of RFP resistance and identify causal mutations for antimicrobial resistance.

METHODS AND MATERIALS

Time-kill assays were performed in a control isolate and three MDR-MRSP isolates at six clinically relevant concentrations [32 to 1,024 × MIC (the minimum inhibitory concentration)]. Whole-genome resequencing and bioinformatic analysis were performed in the resistant strains developed in this assay.

RESULTS

The genomic analysis identified nine antimicrobial resistance genes (ARGs) in MDR-MRSP isolates, which are responsible for resistance to seven classes of antibiotics. RFP activity against all four isolates was consistent with a time-dependent and bacteriostatic response. RFP resistance was observed in six of the 28 time-kill assays, including concentrations 64 × MIC in MDR-MRSP1 isolates at 24 h, 32 × MIC in MDR-MRSP2 at 48 h, 32 × MIC in MDR-MRSP3 at 48 h and 256 × MIC in MDR-MRSP3 at 24 h. Genome-wide mutation analyses in these RFP-resistant strains discovered the causal mutations in the coding region of the rpoB gene.

CONCLUSIONS AND CLINICAL RELEVANCE

A study has shown that 6 mg/kg per os results in plasma concentrations of 600-1,000 × MIC of S. pseudintermedius. Based on our data, this dose should achieve the minimum MIC (×512) to prevent RFP resistance development; therefore, we recommend a minimum daily dose of 6 mg/kg for MDR-MRSP pyoderma treatment when limited antibiotic options are available.

Tedizolid-Rifampicin Combination Prevents Rifampicin-Resistance on in vitro Model of Staphylococcus aureus Mature Biofilm

Staphylococcus aureus infections associated with implanted medical devices are difficult to treat and require long-lasting antibiotic therapies, especially when device removal is not possible or easy such as in the case of joint prostheses. Biofilm formation is a major cause of treatment failure and infection recurrence. This study aimed to test, for the first time, the in vitro combination of tedizolid plus rifampicin on methicillin-sensitive (MSSA ATCC 6538) and methicillin-resistant (MRSA ATCC 43300) S. aureus mature biofilm. Here, we demonstrated that the combination of tedizolid with rifampicin significantly disaggregated pre-formed biofilm of both strains, reduced their metabolic activity and exerted bactericidal activity at clinically meaningful concentrations. Notably, tedizolid was able to completely prevent the emergence of resistance to rifampicin. Moreover these effects were similar to those obtained with daptomycin plus rifampicin, a well-known and widely used combination. Preliminary results on some MRSA clinical isolates confirmed the efficacy of this combination in reducing biofilm biomass and preventing rifampicin resistance onset. Further in vivo studies are needed to confirm the validity of this promising therapeutic option that can be useful against biofilm-associated S. aureus infections.

Silver nanoparticles present high intracellular and extracellular killing against Staphylococcus aureus

OBJECTIVES

Bone and joint infections caused by Staphylococcus aureus are becoming increasingly difficult to treat due to rising antibiotic resistance, resilient biofilms and intracellular survival of S. aureus. It has been challenging to identify and develop antimicrobial agents that can be used to kill extracellular and intracellular bacteria while having limited toxicity towards host cells. In addressing this challenge, this study investigates the antimicrobial efficacy and toxicity of silver nanoparticles (AgNPs).

METHODS

Intracellular bacteria were generated using a co-culture model of human osteoblast cells and S. aureus. Extracellular and intracellular S. aureus were treated with AgNPs, antibiotics and their combinations, and numbers of colonies were quantified. Toxicity of AgNPs against human osteoblast cells was determined by quantifying the number of viable cells after treatment.

RESULTS

AgNPs demonstrated excellent antimicrobial activity against extracellular S. aureus with a 100% killing efficacy at concentrations as low as 56 μM, along with a high intracellular killing efficacy of 76% at 371 μM. AgNPs were non-toxic or slightly toxic towards human osteoblasts at the concentrations studied (up to 927 μM). Moreover, smaller-sized (40 nm) AgNPs were more efficacious in killing bacteria compared with their larger-sized (100 nm) counterparts and synergistic antimicrobial effects against extracellular bacteria were observed when AgNPs were combined with gentamicin.

CONCLUSIONS

AgNPs and their combination with antibiotics have demonstrated high extracellular and intracellular bacterial killing and presented unique aspects for potential clinical applications, especially for chronic and recurrent infections where intracellular bacteria may be the cause.

Evaluation of current dosing guidance for oral rifampicin treatment in adult patients with osteoarticular infections

For management of osteoarticular infections, rifampicin appears to be the key antibiotic. We aimed to evaluate the actual rifampicin dosing regimens using a population pharmacokinetic model of rifampicin in patients with osteoarticular infections. A Monte Carlo simulation study was performed to simulate steady-state plasma concentrations for 1000 randomly sampled subjects using a total daily dose between 600 and 1200 mg (600 and 900 mg once daily, 450 and 600 mg twice daily, or 300 mg 3 times daily). When rifampicin was administered with fusidic acid, the pharmacokinetic/pharmacodynamic (PK/PD) target (area under the curve/minimum inhibitory concentration ≥952) was achieved with all tested dosing regimen, except 600 mg once daily for Staphylococcus epidermidis infections. Without coadministration of fusidic acid, none of tested dosing regimens achieved this PK/PD target. Most recommended drug-dosing regimens allow attaining the fixed area under the curve/minimum inhibitory concentration target for Staphylococcus aureus and coagulase-negative staphylococcal osteoarticular infections. In future studies, PK/PD target for osteoarticular infections in human should also be confirmed.

Nitroxide Functionalized Antibiotics Are Promising Eradication Agents against Staphylococcus aureus Biofilms

Treatment of biofilm-related Staphylococcus aureus infections represents an important medical challenge worldwide, as biofilms, even those involving drug-susceptible S. aureus strains, are highly refractory to conventional antibiotic therapy. Nitroxides were recently shown to induce the dispersal of Gram-negative biofilms in vitro, but their action against Gram-positive bacterial biofilms remains unknown. Here, we demonstrate that the biofilm dispersal activity of nitroxides extends to S. aureus, a clinically important Gram-positive pathogen. Coadministration of the nitroxide CTEMPO (4-carboxy-2,2,6,6-tetramethylpiperidin-1-yloxyl) with ciprofloxacin significantly improved the biofilm eradication activity of the antibiotic against S. aureus Moreover, covalently linking the nitroxide to the antibiotic moiety further reduced the ciprofloxacin minimal biofilm eradication concentration. Microscopy analysis revealed that fluorescent nitroxide-antibiotic hybrids could penetrate S. aureus biofilms and enter cells localized at the surface and base of the biofilm structure. No toxicity to human cells was observed for the nitroxide CTEMPO or the nitroxide-antibiotic hybrids. Taken together, our results show that nitroxides can mediate the dispersal of Gram-positive biofilms and that dual-acting biofilm eradication antibiotics may provide broad-spectrum therapies for the treatment of biofilm-related infections.

The anti-MRSA compound 3-O-alpha-L-(2″,3″-di-p-coumaroyl)rhamnoside (KCR) inhibits protein synthesis in Staphylococcus aureus

Methicillin-resistant S aureus (MRSA) contributes to patient mortality and extended hospital stays. 3-O-alpha-L-(2″,3″-di-p-coumaroyl)rhamnoside (KCR) is a natural product antibiotic that is effective against MRSA but has no known mechanism of action (MOA). We used proteomics to identify the MOA for KCR. Methicillin sensitive S aureus and a mixture of four KCR stereoisomers were tested. A time-kill assay was used to choose a 4 h treatment using KCR at 5× its MIC for proteomic analysis. S aureus was treated in triplicate with KCR, oxacillin or vehicle and quantitative proteomic analysis was carried out using isobaric tags and mass spectrometry. 1190 proteins were identified and 552 were affected by KCR (q < 0.01). Ontology analysis identified 6 distinct translation-related categories that were affected by KCR (PIANO, 10% false-discovery rate) including structural constituent of ribosome, translation, rRNA binding, tRNA binding, tRNA processing and aminoacyl-tRNA ligase activity. Median fold changes (KCR vs Control) for small and large ribosomal components were 1.46 and 1.43 respectively. KCR inhibited the production of luciferase protein in an in vitro assay (IC50 39.6 μg/ml). Upregulation of translation-related proteins in response to KCR indicates that KCR acts to disrupt S aureus protein synthesis. This was confirmed with an in vitro transcription/translation assay. SIGNIFICANCE: Methicillin-resistant S aureus (MRSA) contributes to patient mortality and extended hospital stays. 3-O-alpha-L-(2″,3″-di-p-coumaroyl)rhamnoside (KCR) is a natural product antibiotic that is effective against MRSA but has no known mechanism of action (MOA). Using proteomic analysis we determined that KCR acts by inhibiting protein synthesis. KCR is an exciting novel antibiotic and this work represents an important step in its development towards clinical use.

Characterization of rifampin-resistant Staphylococcus aureus nasal carriage in patients receiving rifampin-containing regimens for tuberculosis

Objectives

This study investigated molecular characteristics of rifampin (RIF)-resistant (RIF-R) Staphylococcus aureus isolates recovered from patients receiving RIF-containing regimens for tuberculosis (TB).

Patients and methods

Patients with TB who received RIF-containing regimens from November 2009 to May 2011 at a medical center were enrolled. Nasal swabs for S. aureus culture were obtained at the time of enrollment, and then every two months until two months after RIF treatment had been completed. Genetic relatedness of the isolates was determined using pulsed-field gel electrophoresis, multilocus sequence typing, and gene typing of spa and SCCmec. The presence of RIF resistance-associated mutations in rpoB, and fusidic acid resistance genes fusB and fusC in the S. aureus isolates were analyzed.

Results

Among the 200 patients enrolled in this study, 152 completed follow-ups during treatment, and 114 completed two months of follow-up after discontinuing use of RIF. At enrollment, ten patients (5%) had nasal colonization with S. aureus, namely eight with methicillin-susceptible S. aureus (MSSA), and two with methicillin-resistant S. aureus (MRSA, ST59-SCCmecIV-RIF-susceptible). All these patients were decolonized after RIF usage. Two patients with MSSA colonization at enrollment showed recolonization with genetically unrelated MSSA strains two months after completion of RIF treatment. There were five ST45-SCCmecV_T-RIF-R strains from two patients isolated during RIF exposure. Sequencing of rpoB in the RIF-R S. aureus isolates revealed different mutation sites between the MSSA and MRSA isolates.

Conclusion

RIF-R S. aureus strains are more likely to result in persistent nasal carriage in TB patients receiving RIF treatment. Monitoring of emergence and possible dissemination of the MRSA ST45 strains among TB patients treated with RIF in Taiwan is warranted.

Identification of the Metabolites of a Novel Anti-MRSA Compound, Kaempferol-3-O-Alpha-L-(2″,3″-di-p-coumaroyl)rhamnoside (KCR), Extracted from American Sycamore

Fractionation of an extract from American sycamore leaves produced the small molecule, kaempferol-3- O-alpha-L-(2″,3″-di- p-coumaroyl)rhamnoside (KCR), which exists in four stereoisomeric forms ( EE, EZ, ZE, and ZZ) at the olefin in the p-coumaroyl; all four isomers exhibit potent anti-MRSA activity in vitro. As part of the preclinical development of KCR, we set out to investigate the metabolites of KCR in mouse plasma as a prelude of ADME studies and therapeutic assessment. When KCR was added to mouse plasma at 37 °C, two new HPLC peaks appeared with increasing intensity as the incubation time increased; their retention times were shorter than that of KCR indicating that KCR was metabolized to produce two compounds that were more polar. HPLC results indicated that the two metabolites mainly came from the ZE and EE isomers and that the ZZ isomer was the most stable. Based on their respective HPLC retention times and UV spectra, these two metabolites were tentatively identified as p-coumaric acid and afzelin; both of which are more polar than KCR. The molecular weights of both metabolites were then confirmed by a Waters Acquity UPLC system with a QDa mass detector. UPLC chromatograms and molecular ions of metabolites 1 and 2 match well with those of reference materials, p-coumaric acid and afzelin, thus confirming the identities of the two major metabolites of KCR. In summary, KCR was metabolized in mouse plasma and two major metabolites ( p-coumaric acid and afzelin) were identified; the metabolites were mainly converted from the ZE and EE isomers.

Impact of Systemic Antibiotics on Staphylococcus aureus Colonization and Recurrent Skin Infection

Background

Staphylococcus aureus colonization poses risk for subsequent skin and soft tissue infection (SSTI). We hypothesized that including systemic antibiotics in the management of S. aureus SSTI, in conjunction with incision and drainage, would reduce S. aureus colonization and incidence of recurrent infection.

Methods

We prospectively evaluated 383 children with S. aureus SSTI requiring incision and drainage and S. aureus colonization in the anterior nares, axillae, or inguinal folds at baseline screening. Systemic antibiotic prescribing at the point of care was recorded. Repeat colonization sampling was performed within 3 months (median, 38 days; interquartile range, 22-50 days) in 357 participants. Incidence of recurrent infection was ascertained for up to 1 year.

Results

Participants prescribed guideline-recommended empiric antibiotics for purulent SSTI were less likely to remain colonized at follow-up sampling (adjusted hazard ratio [aHR], 0.49; 95% confidence interval [CI], .30-.79) and less likely to have recurrent SSTI (aHR, 0.57; 95% CI, .34-.94) than those not receiving guideline-recommended empiric antibiotics for their SSTI. Additionally, participants remaining colonized at repeat sampling were more likely to report a recurrent infection over 12 months (aHR, 2.37; 95% CI, 1.69-3.31). Clindamycin was more effective than trimethoprim-sulfamethoxazole (TMP-SMX) in eradicating S. aureus colonization (44% vs 57% remained colonized, P = .03) and preventing recurrent SSTI (31% vs 47% experienced recurrence, P = .008).

Conclusions

Systemic antibiotics, as part of acute SSTI management, impact S. aureus colonization, contributing to a decreased incidence of recurrent SSTI. The mechanism by which clindamycin differentially affects colonization and recurrent SSTI compared to TMP-SMX warrants further study.

Epidemiology and clinical relevance of Staphylococcus aureus intestinal carriage: a systematic review and meta-analysis

INTRODUCTION

Recent data highlight the importance of screening more than one site for improving the detection of S. aureus colonization. Intestinal carriage is frequently under-investigated and its clinical impact ought to be defined a better way. Areas covered: This review and meta-analysis provide an updated overview of prevalence, characteristics and clinical significance of S. aureus intestinal carriage in different populations, both for methicillin-susceptible and -resistant S. aureus strains. Expert commentary: Intestinal S. aureus carriage is documented with higher prevalence in children and in patients with S. aureus skin and soft tissue infections. This site of colonization was shown to be associated with a high risk of dissemination in the environment and with S. aureus infection. Intestinal carriage is frequently retrieved in nasal carriers, reflecting probably an association with a high bacterial load. Exclusive intestinal carriage present in one third of intestinal carriers can be associated with infection. Comparative genotyping analysis of different strains from nasal and extra-nasal sites of carriage, including the intestinal ones, in the same individuals, would allow a better comprehension of the pathophysiology of S. aureus endogenous infection. It could also permit to improve the prevention of these infections by decolonization of sites implicated in infection genesis.

Rifampicin treatment of canine pyoderma due to multidrug-resistant meticillin-resistant staphylococci: a retrospective study of 32 cases

BACKGROUND

Rifampicin has received increased interest in veterinary dermatology because of its activity against multidrug-resistant meticillin-resistant staphylococci (MRS). There is limited knowledge about the efficacy and safety of rifampicin in dogs.

HYPOTHESIS/OBJECTIVE

To provide information on response to treatment and adverse effects in dogs treated with rifampicin for multidrug-resistant MRS pyoderma.

ANIMALS

Thirty two dogs treated with rifampicin for rifampicin-susceptible multidrug-resistant MRS pyoderma.

METHODS

Retrospective review of medical records, including alanine aminotransferase (ALT) and alkaline phosphatase (ALP) serum activity levels and total bilirubin concentrations, obtained before and throughout the treatment, was performed.

RESULTS

Oral rifampicin as sole systemic antimicrobial therapy (median dose 5 mg/kg twice daily) was effective in 71.88% of cases. Topical antimicrobials were used in most cases. Median duration of rifampicin treatment was five weeks for superficial pyoderma and four weeks for deep pyoderma. Gastrointestinal signs were reported in 15% of treated dogs. Statistically significant increases of ALT (P = 0.045) and ALP (P = 0.0002) values after 3-4 weeks of treatment was observed. The median increase was equal to 0.3 and ×1.5 the upper limit of the reference ranges for ALT and ALP, respectively.

CONCLUSIONS/CLINICAL IMPORTANCE

Oral rifampicin combined with topical antimicrobials can be considered an effective therapeutic option for canine superficial and deep pyoderma caused by rifampicin-susceptible multidrug-resistant MRS. Liver enzyme induction might be the most important cause of ALT and ALP increase associated with rifampicin therapy in dogs.

Prevention of Recurrent Staphylococcal Skin Infections

Staphylococcus aureus infections pose a significant health burden. The emergence of community-associated methicillin-resistant S aureus has resulted in an epidemic of skin and soft tissue infections (SSTI), and many patients experience recurrent SSTI. As S aureus colonization is associated with subsequent infection, decolonization is recommended for patients with recurrent SSTI or in settings of ongoing transmission. S aureus infections often cluster within households, and asymptomatic carriers serve as reservoirs for transmission; therefore, a household approach to decolonization is more effective than measures performed by individuals alone. Novel strategies for the prevention of recurrent SSTI are needed.

Investigation on rifampicin administration from the standpoint of pharmacokinetics/pharmacodynamics in a neutropenic murine thigh infection model

BACKGROUND

The purpose of this study was to examine the pharmacokinetics/pharmacodynamics of rifampicin against methicillin-susceptible Staphylococcus aureus (MSSA), methicillin-resistant S. aureus (MRSA), and vancomycin-intermediate S. aureus (VISA) in a neutropenic murine thigh infection model.

METHODS

Three S. aureus isolates (MSSA [ATCC 25923], MRSA and VISA [Mu50]) with rifampicin MIC 0.06 to >256 μg/mL were tested. The efficacy was calculated as the change in bacterial density. A maximum effect model was used to determine the PK/PD index that best described the dose-response data.

RESULTS

The area under the curve (AUC)/MIC and maximum concentration of drug in serum (Cmax/MIC) were the best correlated with in vivo efficacy (AUC/MIC, R(2) = 0.96; Cmax/MIC, R(2) = 0.97) for S. aureus ATCC 25923 strain, and the dose fractionation-response study did not show significantly different antimicrobial activity (p = 0.10). The AUC/MIC values associated with stasis and 1-log kill for the S. aureus ATCC 25923 strain were 386 and 952, respectively. On the other hand, no antimicrobial efficacy was observed against two strains (MRSA and VISA) with MIC of 128 μg/mL or more.

CONCLUSION

Rifampicin demonstrated concentration-dependent killing. The AUC/MIC was a predictive PK/PD index.

Surgical debridement with retention of spinal instrumentation and long-term antimicrobial therapy for multidrug-resistant surgical site infections after spinal surgery: a case series

PURPOSE

Post-operative surgical site infection (SSI) is one of the most significant complications after instrumented spinal surgery. However, implant retention feasibility for early-onset multidrug-resistant SSI is still controversial. We aimed to verify our therapeutic strategy, surgical debridement with implant retention and long-term antimicrobial therapy for post-operative early-onset multidrug-resistant SSI.

METHODS

We retrospectively analyzed the clinical course of 11 cases [eight men and three women, with a mean age of 70.4 (54-82) years] with early-onset multidrug-resistant SSI out of 409 consecutive cases of spinal instrumentation surgery performed between 2007 and 2013 at our institution.

RESULTS

The median duration of follow-up was 868 (178-1,922) days. All SSIs were controlled, without recurrence during follow-up. The microbial pathogens were methicillin-resistant Staphylococcus aureus (seven cases), multidrug-resistant Corynebacterium (two cases), methicillin-resistant Staphylococcus epidermidis (one case), and methicillin-resistant coagulase-negative Staphylococcus aureus (one case). The mean duration from SSI diagnosis to surgery was 2.9 (1-6) days. Ten patients underwent surgical debridement with implant retention. No patients required multiple operations. All patients were given antimicrobial treatments. Mean duration of intravenous antimicrobials (vancomycin, vancomycin+ piperacillin/tazobactam, or gentamicin) was 66.5 (12-352) days and 336 (89-1,673) days for oral antimicrobials (rifampicin + sulfamethoxazole/trimethoprim, sulfamethoxazole/trimethoprim, or minomycin). The mean duration of clinical signs and symptom recovery was 31.0 (7-73) days, and the mean time for normalization of C-reactive protein was 54.5 (7-105) days.

CONCLUSIONS

Early-onset multidrug-resistant SSI was successfully treated by surgical debridement with implant retention and long-term antimicrobial therapy.

HPLC Plasma Assay of a Novel Anti-MRSA Compound, Kaempferol-3-O-Alpha-L-(2″,3″-di-p-coumaroyl)rhamnoside, from Sycamore Leaves

Methicillin-resistant Staphylococcus aureus (MRSA) is a serious pathogen that is resistant to current antibiotic therapy. Thus, there is an urgent need for novel antimicrobial agents that can effectively combat these new strains of drug-resistant “superbugs”. Recently, fractionation of an extract from Platanus occidentalis (American sycamore) leaves produced an active kaempferol molecule, 3- O-alpha-L-(2″,3″-di- p-coumaroyl)rhamnoside (KCR), in four isomeric forms; all four isomers exhibit potent anti-MRSA activity. In order to further the preclinical development of KCR as a new antibiotic class, we developed and validated a simple analytical method for assaying KCR plasma concentration. Because KCR will be developed as a new drug, although comprising four stereoisomers, the analytical method was devised to assay the total amount of all four isomers. In the present work, both a plasma processing procedure and an HPLC method have been developed and validated. Mouse plasma containing KCR was first treated with ethanol and then centrifuged. The supernatant was dried, suspended in ethanol, centrifuged, and the supernatant was injected into an HPLC system comprising a Waters C18, a mobile phase composing methanol, acetonitrile, and trifluoroacetic acid and monitored at 313 nm. The method was validated by parameters including a good linear correlation, a limit of quantification of 0.27 μg/mL, and high accuracy. In summary, this method allows a rapid analysis of KCR in the plasma samples for pharmacokinetics studies.

Topical Therapy for Methicillin-Resistant Staphylococcus aureus Colonization Impact on Infection Risk

Objective.

We evaluated the usefulness of topical decolonization therapy for reducing the risk of methicillin-resistant Staphylococcus aureus (MRSA) infection among MRSA-colonized inpatients.

Design.

Retrospective cohort study.

Setting and Intervention.

Three hospitals with universal surveillance for MRSA; at their physician's discretion, colonized patients could be treated with a 5-day course of nasal mupirocin calcium 2%, twice daily, plus Chlorhexidine gluconate 4% every second day.

Patients and Methods.

MRSA carriers were later retested for colonization (407 subjects; study 1) or followed up for development of MRSA infection (933 subjects; study 2). Multivariable methods were used to determine the impact of decolonization therapy on the risks of sustained colonization (in study 1) and MRSA infection (in study 2).

Results.

Independent risk factors for sustained colonization included residence in a long-term care facility (odds ratio [OR], 1.8 [95% confidence interval {CI}, 1.1–3.2]) and a pressure ulcer (OR, 2.3 195% CI, 1.2–4.4]). Mupirocin at any dose decreased this risk, particularly during the 30-60-day period after therapy; mupirocin resistance increased this risk (OR, 4.1 [95% CI, 1.6–10.7]). Over a median follow-up duration of 269 days, 69 (7.4%) of 933 patients developed infection. Independent risk factors for infection were length of stay (hazard ratio [HR], 1.2 per 5 additional days [95% CI, 1.0–1.4]), chronic lung disease (HR, 1.7 [95% CI, 1.0–2.8]), and receipt of non-MRSA-active systemic antimicrobial agents (HR, 1.8 [95% CI, 1.1–3.1]). Receipt of mupirocin did not affect the risk of infection, although there was a trend toward delayed infection among patients receiving mupirocin (median time to infection, 50 vs 15.5 days; P = .06).

Conclusions.

Mupirocin-based decolonization therapy temporarily reduced the risk of continued colonization but did not decrease the risk of subsequent infection.

Canine superficial bacterial folliculitis: current understanding of its etiology, diagnosis and treatment

Superficial bacterial folliculitis (SBF) is more common in the dog than other mammalian species. Until recently, a successful outcome in cases of canine SBF was possible by administering a potentiated amoxicillin, a first generation cephalosporin or a potentiated sulfonamide. Unfortunately, this predictable susceptibility has changed, because methicillin resistant Staphylococcus pseudintermedius (MRSP) and Staphylococcus aureus (MRSA) are becoming more prevalent in canine SBF cases. The increasing frequency of multidrug resistance complicates the selection of antimicrobial therapy. Antimicrobial agents that were once rarely used in cases of canine SBF, such as amikacin, rifampicin and chloramphenicol, are becoming the drugs of choice, based on bacterial culture and susceptibility testing. Furthermore, changes in antimicrobial susceptibility have helped to re-emphasize the importance of a multimodal approach to treatment of the disease, including topical therapy. Due to the increasing frequency of identification of highly resistant Staphylococcus spp., topical antimicrobial therapy, including the use of diluted sodium hypochlorite (bleach), is becoming necessary to successfully treat some cases of canine SBF. Other important antiseptics that can be used include chlorhexidine, benzoyl peroxide, ethyl lactate, triclosan and boric acid/acetic acid. This review discusses the diagnostic and therapeutic management of canine SBF, with a special emphasis on treating methicillin resistant staphylococcal infections.

Report of a transient increase in tunneled catheter infections following dialysis facility transfer to a prefabricated structure

PURPOSE

Despite the efforts to promote the native artero-venous fistula as dialysis access, the use of tunneled central venous catheters (tCVC) is increasing. Main complications remain infections of the access, and the environment plays an important role in determining them; however, no studies are available that report dialysis provided in prefabricated temporary buildings. The aim of our study was to assess the incidence of tCVC infections in a container building.

METHODS

Since May 2009 our Dialysis Center has been located in a container building. The occurrence of local and systemic infections of tCVC when dialysis was provided in the container was compared with the previous two years, when dialysis was provided at the "Home" center. Each year was also divided into semesters to maintain the temporary relationship between the new location and the infections.

RESULTS

tCVCs represented approximately 13% of all vascular accesses. In the first six months in the temporary building, 50% of patients presented infections, compared to 13% to 20% during the other periods (P=0.02). In the first six months in the container the incidence of infections was 1.44 per 1000 catheters-days, higher than in any other semester (P=0.02). More infections requiring systemic antibacterial agents occurred over this period.

CONCLUSIONS

Our study demonstrates that, when a dialysis center is moved to a prefabricated temporary building, the likelihood of tCVC infections increases within the initial months and returns back to the previous levels after a period of adaptation.

Descolonização de portadores de Staphylococcus aureus: indicações, vantagens e limitações

O objetivo deste artigo foi estabelecer as principais indicações, vantagens e limitações da descolonização de pacientes portadores de Staphylococcus aureus. Procedeu-se a uma revisão integrativa da literatura, com busca de artigos nas bases de dados LILACS, MEDLINE, Science Direct, SCOPUS e Isi Web of Knowledge, e em publicações a partir de 1999. As principais indicações encontradas foram direcionadas aos pacientes considerados de alto risco (admitidos em UTI, submetidos à cirurgia, com longa permanência, etc.). As vantagens fundamentaram-se na erradicação do microrganismo, redução da taxas de infecção e na disseminação destes. As controvérsias se deram pela possibilidade do aumento da resistência bacteriana e pela falta de evidências científicas sobre a eficácia da eliminação do microrganismo colonizante e da redução da taxa de infecção. Observou-se que a descolonização não deve ser indicada como rotina, mas, sim, deve ser recomendada apenas para pacientes de risco e durante surtos.

Antimicrobial options in the treatment of adult staphylococcal bone and joint infections in an era of drug shortages

Staphylococcus aureus is the most pathogenic bacterium and the most common cause of osteomyelitis, affecting 50% to 70% of cases. Many antistaphylococcal agents with varying activity against methicillin-susceptible S aureus and methicillin-resistant S aureus are available in the US market. This article reviews the most common antistaphylococcal agents used in the treatment of bone and joint infections in adult patients and focuses on the antimicrobial agent's mechanism of action, US Food and Drug Administration-approved indications, place in therapy, monitoring parameters, and common side effects.

Selection of antibiotics for meticillin-resistant Staphylococcus pseudintermedius: time to revisit some old drugs?

The aim of this review is to consider systemic therapy options for meticillin-resistant Staphylococcus pseudintermedius (MRSP). Infections caused by MRSP in small animals--particularly dogs--have been frustrating veterinarians in recent years. After a susceptibility test is performed, veterinarians are left to select from drugs that have not been frequently encountered on a susceptibility report. Some of these are old drugs that have not been used regularly by veterinary dermatologists. As MRSP is, by definition, resistant to all β-lactam antibiotics, including cephalosporins, penicillins and amoxicillin-clavulanate combinations, the β-lactam drugs are not an option for systemic treatment. As most MRSPs are multidrug resistant, familiar drugs, such as trimethoprim-sulfonamides, fluoroquinolones, macrolides and lincosamides (clindamycin), are also not usually an option for treatment. Therefore, veterinarians are left with drugs such as rifampicin, chloramphenicol, tetracyclines, aminoglycosides and vancomycin to choose from on the basis of an in vitro susceptibility test. Some of these drugs were originally approved over 50 years ago and may not be familiar to some veterinarians. Each of these drugs possesses unique properties and has particular advantages and disadvantages. Veterinarians should be particularly aware of the adverse effects, limitations and precautions when using these drugs. New drugs also have been developed for meticillin-resistant Staphylococcus aureus in humans. These include linezolid, ceftaroline, daptomycin and tigecycline. Although these drugs are very infrequently--if ever--considered for veterinary use, the properties of these drugs should also be known to veterinary dermatologists.

Staphylococcal decolonisation: an effective strategy for prevention of infection?

Staphylococcus aureus decolonisation--treatment to eradicate staphylococcal carriage--is often considered as a measure to prevent S aureus infection. The most common approach to decolonisation has been intranasal application of mupirocin either alone or in combination with antiseptic soaps or systemic antimicrobial agents. Some data support the use of decolonisation in surgical patients colonised with S aureus, particularly in those undergoing cardiothoracic procedures. Although this intervention has been associated with low rates of postoperative S aureus infection, whether overall rates of infection are also decreased is unclear. Patients undergoing chronic haemodialysis or peritoneal dialysis might benefit from decolonisation, although repeated courses of treatment are needed, and the effects are modest. Eradication of meticillin-resistant S aureus (MRSA) carriage has generally been difficult, and the role of decolonisation as an MRSA infection control measure is uncertain. The efficacy of decolonisation of patients with community-associated MRSA has not been established, and the routine use of decolonisation of non-surgical patients is not supported by data.

Current use for old antibacterial agents: polymyxins, rifamycins, and aminoglycosides

This article reviews three classes of antibacterial agents that are uncommonly used in bacterial infections and therefore can be thought of as special-use agents. The polymyxins are reserved for gram-negative bacilli that are resistant to virtually all other classes of drugs. Rifampin is used therapeutically, occasionally as a companion drug in treatment of refractory gram-positive coccal infections, especially those involving foreign bodies. Rifaximin is a new rifamycin that is a strict enteric antibiotic approved for treatment of traveler's diarrhea and is showing promise as a possible agent for refractory Clostridium difficile infections. The aminoglycosides are used mainly as companion drugs for the treatment of resistant gram-negative bacillary infections and for gram-positive coccal endocarditis.

Review: Staphylococcus aureus and MRSA in cystic fibrosis

BACKGROUND

Staphylococcus aureus (S. aureus) is one of the earliest bacteria detected in infants and children with cystic fibrosis (CF). The rise of methicillin resistant S. aureus (MRSA) in the last 10 years has caused a lot of attention to this organism.

RESULTS

The aim of this review is to provide a general overview of methicillin sensitive S. aureus (MSSA) and MRSA, discuss special aspects of S. aureus in cystic fibrosis, and to review treatment concepts. Microbiology of the organism will be reviewed along with data regarding the epidemiology of both MSSA and MRSA. Antibiotic treatments both in regards to acute management and eradication of MSSA and MRSA will be reviewed. Prophylaxis of MSSA in CF remains controversial. Treatment with anti-staphylococcal agents reduces the infection rate with MSSA but may lead to a higher rate of infection with P. aeruginosa. In regards to MRSA, there is a paucity of clinical data regarding approaches to eradication.

CONCLUSIONS

To advance the care of CF patients, controlled clinical trials are urgently needed to find the optimal approach to treating CF patients who are infected with either MSSA or MRSA.

Prevalence of nasal Staphylococcus aureus carriage in the patients undergoing hemodialysis and evaluation of risk factors and laboratory parameters

BACKGROUND

In this study, we aimed to determine the nasal carriage rate of Staphylococcus aureus and risk factors in hemodialysis (HD) patients.

METHODS

One hundred eighty-four HD patients were evaluated. A second sample was taken from the subjects, the wipe samples of whom were isolated as S. aureus. And subjects whose second samples' results were the same were deemed as S. aureus carriers.

RESULTS

Fifty-two (28.3%) patients were identified as S. aureus carriers. In the control group, S. aureus carriage has been found out as 14.9% in 116 healthy subjects. The isolation rate of S. aureus has been found statistically significantly high in the age group of 41-61 years. But, methicillin-resistant S. aureus (MRSA) isolation ratio has been statistically high in the group over the age of 61 years. Sepsis history and gastrointestinal system disease development is closely related to bacterial isolation. MRSA isolation ratios have been found high in chronic lung disease patients, diabetic patients, patients with infection history, and patients with impaired general state of health. The carriage ratios have been found higher in the patients who are settled in urban areas, are subjected to dialysis for more than 10 years, and are hospitalized in the past year. However, the difference between the other groups is not statistically significant.

CONCLUSIONS

S. aureus carriage must be screened on regular intervals in HD patients. Nasal S. aureus carriage follow-up and treatment is a process that will protect patients from more severe clinical pictures.

Effectiveness of a protocol for the prevention of hemodialysis venous catheter-related infections

PURPOSE

Infections are a major complication of the use of hemodialysis central venous catheters. In our study we evaluated the efficacy of the hemodialysis central venous catheter protocol management adopted in our center, through a retrospective analysis of all hemodialysis central venous catheters inserted over a period of 6 years.

METHODS

Seventy-three tunneled central venous catheters and 75 temporary central venous catheters were inserted in our center from 2003 to 2008 in 148 patients.

RESULTS

During the follow-up we observed 30 infective events (16 assessed as bacteremias, 14 subcutaneous tunnel or exit site infections) with a rate of 0.65/1,000 days of central venous catheter implantation.

CONCLUSIONS

Our experience confirms, in a 72-month follow-up, the importance of careful central venous catheter management as a crucial feature in reducing the incidence of infective events in patients with central venous catheters in dialytic treatment.

Novel classes of antibiotics or more of the same?

The world is running out of antibiotics. Between 1940 and 1962, more than 20 new classes of antibiotics were marketed. Since then, only two new classes have reached the market. Analogue development kept pace with the emergence of resistant bacteria until 10-20 years ago. Now, not enough analogues are reaching the market to stem the tide of antibiotic resistance, particularly among gram-negative bacteria. This review examines the existing systemic antibiotic pipeline in the public domain, and reveals that 27 compounds are in clinical development, of which two are new classes, both of which are in Phase I clinical trials. In view of the high attrition rate of drugs in early clinical development, particularly new classes and the current regulatory hurdles, it does not seem likely that new classes will be marketed soon. This paper suggests that, if the world is to return to a situation in which there are enough antibiotics to cope with the inevitable ongoing emergence of bacterial resistance, we need to recreate the prolific antibiotic discovery period between 1940 and 1962, which produced 20 classes that served the world well for 60 years. If another 20 classes and their analogues, particularly targeting gram-negatives could be produced soon, they might last us for the next 60 years. How can this be achieved? Only a huge effort by governments in the form of finance, legislation and providing industry with real incentives will reverse this. Industry needs to re-enter the market on a much larger scale, and academia should rebuild its antibiotic discovery infrastructure to support this effort. The alternative is Medicine without effective antibiotics.

Molecular basis of rifampicin resistance in methicillin-resistant Staphylococcus pseudintermedius isolates from dogs

BACKGROUND

Methicillin-resistant Staphylococcus pseudintermedius (MRSP) often display resistance to almost all classes of antimicrobial agents used in veterinary medicine. In the present study, we investigated the emergence of rifampicin resistance in MRSP, the persistence of these isolates and identified the corresponding mutations in the rpoB gene.

METHODS

In addition to two rifampicin-resistant MRSP isolates from a multicentre study, consecutive MRSP isolates collected prior to and after rifampicin therapy from nine dogs at five Dutch veterinary hospitals were included in this study. The isolates were tested for resistance to rifampicin and other antimicrobial agents. The rifampicin resistance-determining region (RRDR) within the rpoB gene of the rifampicin-resistant and -susceptible isolates was amplified by PCR and sequenced. PFGE served to determine the genetic relationships of the MRSP isolates.

RESULTS

Two MRSP isolates of the multicentre study showed mutations at position 513 or 522 in the RRDR of the rpoB gene. In contrast to the rifampicin-susceptible isolates, all rifampicin-resistant MRSP isolates showed mutations at one or two of the amino acid positions 508, 509, 513, 516, 522, 526 and 531. In most strains, a single amino acid exchange was observed. PFGE analysis confirmed that the rifampicin-resistant MRSP isolates were indistinguishable from or closely related to the rifampicin-susceptible isolate obtained from the same dog prior to rifampicin application.

CONCLUSIONS

Therapy of MRSP infections with rifampicin results in the rapid emergence of rifampicin resistance and these isolates can persist for months. As a consequence, single therapy with rifampicin is not recommended.

Investigation of pulmonary infection pathogens in neurological intensive care unit

Purpose:

The purpose of this study is to investigate the distribution and antimicrobial susceptibility of pathogenic bacteria in inpatients with pulmonary infection in the neurological intensive care unit (NICU).

Methods:

A total of 947 sputum specimens of 428 inpatients from May 2007 to May 2008 in the NICU were enrolled in the study, and bacterial identification and antibiotic susceptibility tests were analyzed using a VITEK 2 system.

Results:

A total of 400 positive bacterial strains were separated from 947 sputum specimens, with Gram-negative bacteria accounting for 69.0% of the total strains collected. The most common strain of Gram-negative bacteria was Klebsiella pneumoniae (20.5%). Gram-positive bacteria accounted for 10.0% of the total strains, with the most common strain being Staphylococcus aureus (2.5%). Fungal species accounted for 21.0% of the total strains, and the most common strain collected was Candida albicans (12.25%). Imipenem was the most effective antibiotic against Gram-positive and Gram-negative bacteria. The drug resistance rate of Gram-positive bacteria to penicillin G was 100%, and the Gram-positive bacteria were 100% sensitive to teicoplanin, vancomycin, and linezolid.

Conclusions:

Gram-negative bacterial infections account for the majority of pulmonary infections in the NICU, with fungal infections being the second most common infection type observed. In addition, fungal infections seem to be related to mortality in the NICU.

Clinical practice guidelines by the infectious diseases society of america for the treatment of methicillin-resistant Staphylococcus aureus infections in adults and children

Evidence-based guidelines for the management of patients with methicillin-resistant Staphylococcus aureus (MRSA) infections were prepared by an Expert Panel of the Infectious Diseases Society of America (IDSA). The guidelines are intended for use by health care providers who care for adult and pediatric patients with MRSA infections. The guidelines discuss the management of a variety of clinical syndromes associated with MRSA disease, including skin and soft tissue infections (SSTI), bacteremia and endocarditis, pneumonia, bone and joint infections, and central nervous system (CNS) infections. Recommendations are provided regarding vancomycin dosing and monitoring, management of infections due to MRSA strains with reduced susceptibility to vancomycin, and vancomycin treatment failures.

Current use for old antibacterial agents: polymyxins, rifamycins, and aminoglycosides

This article reviews three classes of antibacterial agents that are uncommonly used in bacterial infections and therefore can be thought of as special-use agents. The polymyxins are reserved for gram-negative bacilli that are resistant to virtually all other classes of drugs. Rifampin is used therapeutically, occasionally as a companion drug in treatment of refractory gram-positive coccal infections, especially those involving foreign bodies. Rifaximin is a new rifamycin that is a strict enteric antibiotic approved for treatment of traveler's diarrhea and is showing promise as a possible agent for refractory Clostridium difficile infections. The aminoglycosides are used mainly as companion drugs for the treatment of resistant gram-negative bacillary infections and for gram-positive coccal endocarditis.

Update: Methicillin-resistant Staphylococcus aureus screening and decolonization in cardiac surgery

Methicillin-resistant Staphylococcus aureus (MRSA) has become a concerning multidrug-resistant organism, expanding further outside the hospital setting. Cardiothoracic surgery patients are at an increased risk for mediastinitis and other surgical site infections, which may be further complicated by MRSA. To reduce MRSA surgical site infections, multidisciplinary active surveillance should be implemented in at least high-risk patients, incorporating basic infection control practices, appropriate antibiotic prophylaxis, and decolonization. This article will review the various guidelines, addressing the role of MRSA active surveillance in cardiothoracic surgery, and provide guidance for cardiothoracic surgeons.

Trimethoprim-sulfamethoxazole for methicillin-resistant Staphylococcus aureus: a forgotten alternative?

Methicillin-resistant Staphylococcus aureus (MRSA) is a growing infectious concern, mainly in the context of its rapid adaptation to novel antibiotic options for its treatment and the growing morbidity, mortality, and healthcare costs associated with its emergence. the authors sought to investigate whether an older antibiotic, such as trimethoprim-sulfamethoxazole (SXT), may have a role in treating MRSA-related infections, according to the available literature on the subject. The authors reviewed literature data on: resistance of MRSA to SXT worldwide in recent years, efficacy of SXT for MRSA decolonization or prophylaxis from MRSA infections, and clinical therapeutic efficacy of SXT in treating mild or severe community-acquired or hospital-acquired MRSA infections. Resistance varies worldwide, in general being low in the industrialized world and higher in developing countries. SXT is one of the numerous understudied options for MRSA decolonization and is growingly recognized as potentially effective in preventing MRSA infections in certain settings. Limited data on its therapeutic efficacy are encouraging, at least for mild, community-acquired infections. SXT may represent a cost-effective alternative weapon against MRSA. Its utility against this increasingly threatening pathogen need clarification through further clinical trials.

The role of healthcare personnel in the maintenance and spread of methicillin-resistant Staphylococcus aureus

Healthcare workers may acquire methicillin-resistant Staphylococcus aureus (MRSA) from patients, both hospital and home environments, other healthcare workers, family and public acquaintances, and pets. There is a consensus of case reports and series which now strongly support the role for MRSA-carrying healthcare personnel to serve as a reservoir and as a vehicle of spread within healthcare settings. Carriage may occur at a number of body sites and for short, intermediate, and long terms. A number of approaches have been taken to interrupt the linkage of staff-patient spread, but most emphasis has been placed on handwashing and the treatment of staff MRSA carriers. The importance of healthcare workers in transmission has been viewed with varying degrees of interest, and several logistical problems have arisen when healthcare worker screening is brought to the forefront. There is now considerable support for the screening and treatment of healthcare workers, but it is suggested that the intensity of any such approach must consider available resources, the nature of the outbreak, and the strength of epidemiological associations. The task of assessing healthcare personnel carriage in any context should be shaped with due regard to national and international guidelines, should be honed and practiced according to local needs and experience, and must be patient-oriented.

Vascular access-related infections: definitions, incidence rates, and risk factors

Hemodialysis is associated with a high risk of morbidity and mortality, often caused by infections. Infections account for approximately 15% of all deaths in this patient population (the second leading cause after cardiovascular events) and for about one-fifth of admissions. Approximately one-fourth of infection-related admissions are caused by dialysis-associated peritonitis or vascular access infection that may lead to such significant complications as endocarditis or death. Published studies that assessed the determinants of hemodialysis-related vascular infections reported inconsistent findings. Variations in the definitions of infection among these studies despite the existence of standard guidelines proposed by at least 3 major work groups may explain, at least in part, these inconsistencies. A comprehensive in-depth review of those studies is needed to examine the inconsistencies in the published results. We first revised the existing vascular access-related infection definitions, then conducted a narrative review of the published literature that examined predictors of vascular access-related infections, highlighting the heterogeneity in methods and findings. Better understanding of the risk factors for vascular access-related infections may inform efficacious prevention strategies and lead to early detection of infections and improved patient care.

Intestinal carriage of Staphylococcus aureus: how does its frequency compare with that of nasal carriage and what is its clinical impact?

The bacterial species Staphylococcus aureus, including its methicillin-resistant variant (MRSA), finds its primary ecological niche in the human nose, but is also able to colonize the intestines and the perineal region. Intestinal carriage has not been widely investigated despite its potential clinical impact. This review summarizes literature on the topic and sketches the current state of affairs from a microbiological and infectious diseases' perspective. Major findings are that the average reported detection rate of intestinal carriage in healthy individuals and patients is 20% for S. aureus and 9% for MRSA, which is approximately half of that for nasal carriage. Nasal carriage seems to predispose to intestinal carriage, but sole intestinal carriage occurs relatively frequently and is observed in 1 out of 3 intestinal carriers, which provides a rationale to include intestinal screening for surveillance or in outbreak settings. Colonization of the intestinal tract with S. aureus at a young age occurs at a high frequency and may affect the host's immune system. The frequency of intestinal carriage is generally underestimated and may significantly contribute to bacterial dissemination and subsequent risk of infections. Whether intestinal rather than nasal S. aureus carriage is a primary predictor for infections is still ill-defined.