N-chlorotaurine, a potent weapon against multiresistant bacteria.

AIMS: N-chlorotaurine (NCT) is a body-own mild oxidizing antiseptic that can be applied topically as a well-tolerated anti-infective at many body sites. The objective of this study was to demonstrate its activity against representative nosocomial multidrug-resistant bacteria. METHODS AND RESULTS: The bactericidal activity of NCT was tested in quantitative killing assays against a panel of multiresistant Gram-positive and Gram-negative clinical isolates. N-chlorotaurine (1%, 55 mmol l-1 ) reduced the number of CFU of strains of methicillin-resistant Staphylococcus aureus, linezolid-resistant Staphylococcus epidermidis, vancomycin-resistant, and linezolid- and vancomycin-resistant Enterococcus faecium, 3MRGN and 4MRGN Escherichia coli, Pseudomonas aeruginosa, Acinetobacter baumannii and Klebsiella pneumoniae by at least 2 log10 steps after 15 min and completely or nearly to the detection limit after 30 min at pH 7·1 and 37°C. CONCLUSION: The activity of NCT against these clinical isolates is similar to that against non-resistant ATCC strains and therefore not influenced by antibiotic resistance. This can be explained by the oxidizing and chlorinating mechanism of action of NCT, which leads to an attack of multiple targets in the microorganisms. SIGNIFICANCE AND IMPACT OF THE STUDY: The bactericidal spectrum of NCT is not restricted by resistance against antibiotics. Therefore, it can be used against resistant strains, too.

The correct blood volume for paediatric blood cultures: a conundrum?

BACKGROUND: Bloodstream infections (BSIs) are a major cause of morbidity and mortality in paediatric patients. For fast and accurate diagnosis, blood culture (BC) is the reference standard. However, the procedure for blood sampling in paediatric patients, particularly the optimal blood volume, is the subject of controversy stemming from a lack of knowledge of the bacterial load and because of several obstacles such as low intravascular volume and the risk of causing anaemia. AIMS: The aim of this narrative review is to summarize current knowledge on blood sampling in paediatric patients for BC purposes, in particular blood volume and number and type of BC bottles needed for reasonable future guidelines/recommendations. SOURCES: A comprehensive literature search of PubMed, including all publications in English, was performed in June 2019 using the search terms 'blood culture', 'blood volume', 'bloodstream infection', 'diagnostic', 'paediatric' and/or 'sepsis'. CONTENT: The amount of inoculated blood determines the sensitivity, specificity and time to positivity of a BC, and low-level bacteraemia (≤10 cfu/mL) in paediatric patients is presumed to be more common than reported. Current approaches for 'adequate' blood volume for paediatric BC are mainly weight- or age-dependent. Of these recommendations, the scheme devised by Gaur and colleagues seems most appropriate and calls for a sample of 1-1.5 mL for children weighing <11 kg and 7.5 mL for a patient weight of 11-17 kg to be drawn into one BC bottle. Inclusion of a more detailed grading in the weight range 4-14 kg, as published by Gonsalves and colleagues, might be useful. IMPLICATIONS: This review could be important for future guidelines on paediatric BC collection and thus could contribute to improving patient management and lowering the economic and global health burden associated with BSI. Furthermore, upcoming molecular-based approaches with low sample volumes might be an interesting alternative.

High-quality endoscope reprocessing decreases endoscope contamination.

OBJECTIVES: Several outbreaks of severe infections due to contamination of gastrointestinal (GI) endoscopes, mainly duodenoscopes, have been described. The rate of microbial endoscope contamination varies dramatically in literature. The aim of this multicentre prospective study was to evaluate the hygiene quality of endoscopes and automated endoscope reprocessors (AERs) in Tyrol/Austria. METHODS: In 2015 and 2016, a total of 463 GI endoscopes and 105 AERs from 29 endoscopy centres were analysed by a routine (R) and a combined routine and advanced (CRA) sampling procedure and investigated for microbial contamination by culture-based and molecular-based analyses. RESULTS: The contamination rate of GI endoscopes was 1.3%-4.6% according to the national guideline, suggesting that 1.3-4.6 patients out of 100 could have had contacts with hygiene-relevant microorganisms through an endoscopic intervention. Comparison of R and CRA sampling showed 1.8% of R versus 4.6% of CRA failing the acceptance criteria in phase I and 1.3% of R versus 3.0% of CRA samples failing in phase II. The most commonly identified indicator organism was Pseudomonas spp., mainly Pseudomonas oleovorans. None of the tested viruses were detected in 40 samples. While AERs in phase I failed (n = 9, 17.6%) mainly due to technical faults, phase II revealed lapses (n = 6, 11.5%) only on account of microbial contamination of the last rinsing water, mainly with Pseudomonas spp. CONCLUSIONS: In the present study the contamination rate of endoscopes was low compared with results from other European countries, possibly due to the high quality of endoscope reprocessing, drying and storage.

How to: identify non-tuberculous Mycobacterium species using MALDI-TOF mass spectrometry.

BACKGROUND: The implementation of MALDI-TOF MS for microorganism identification has changed the routine of the microbiology laboratories as we knew it. Most microorganisms can now be reliably identified within minutes using this inexpensive, user-friendly methodology. However, its application in the identification of mycobacteria isolates has been hampered by the structure of their cell wall. Improvements in the sample processing method and in the available database have proved key factors for the rapid and reliable identification of non-tuberculous mycobacteria isolates using MALDI-TOF MS. AIMS: The main objective is to provide information about the proceedings for the identification of non-tuberculous isolates using MALDI-TOF MS and to review different sample processing methods, available databases, and the interpretation of the results. SOURCES: Results from relevant studies on the use of the available MALDI-TOF MS instruments, the implementation of innovative sample processing methods, or the implementation of improved databases are discussed. CONTENT: Insight about the methodology required for reliable identification of non-tuberculous mycobacteria and its implementation in the microbiology laboratory routine is provided. IMPLICATIONS: Microbiology laboratories where MALDI-TOF MS is available can benefit from its capacity to identify most clinically interesting non-tuberculous mycobacteria in a rapid, reliable, and inexpensive manner.

Cross-sectional point prevalence survey to study the environmental contamination of nosocomial pathogens in intensive care units under real-life conditions.

BACKGROUND: In intensive care units (ICUs), inanimate surfaces and equipment may be contaminated by nosocomial pathogens, including multi-drug-resistant micro-organisms. AIMS: To assess the degree of environmental contamination close to and distant from patients, and contamination of healthcare workers' (HCWs) hands with nosocomial pathogens under real-life conditions and to investigate potential transmission events. METHODS: Over the course of three weeks, agar contact samples were taken close to and distant from patient areas and from HCWs' hands in eight ICUs of a tertiary care hospital in Innsbruck, Austria. Each ICU was visited once without announcement. Species identification and antimicrobial susceptibility testing were performed according to standard methods, and corresponding strains from patient, environment and hand samples were genotyped using pulsed-field gel electrophoresis. FINDINGS: Among 523 samples, HCWs' hands were most frequently contaminated with potentially pathogenic bacteria (15.2%), followed by areas close to patients (10.9%) and areas distant from patients (9.1%). Gram-positive bacteria were identified most often (67.8%), with Enterococcus spp. being the most prevalent species (70% vancomycin sensitive and 30% vancomycin resistant) followed by Staphylococcus aureus, of which 64% were classified as meticillin-resistant Staphylococcus aureus. Molecular typing documented identical strains among patient, environment and hand isolates. CONCLUSION: This study found widespread contamination of the ICU environment with clinically relevant pathogens, including multi-drug-resistant micro-organisms, despite cleaning and disinfection. The bioburden might not be restricted to areas close to patients. The role of extended environmental disinfection of areas distant from patients in order to improve infection prevention needs further discussion.

Mammary candidiasis: molecular-based detection of Candida species in human milk samples.

In this prospective and monocentric study, we investigated the performance of a commercialized real-time polymerase chain reaction (RT-PCR) test system for the specific detection of DNA from Candida albicans, C. dubliniensis, C. glabrata, C. krusei, C. lusitaniae, C. parapsilosis, and C. tropicalis in human milk samples of patients suspicious of mammary candidiasis. For this purpose, 43 breast-feeding women with characteristic symptoms of mammary candidiasis and 40 asymptomatic controls were enrolled. By culture, Candida spp. were detected in 8.8 % (4/46) and 9.3 % (4/43) of patient and control samples, respectively. Candida albicans (2/46), C. parapsilosis (1/46), and C. guilliermondii (1/46) were present in patient samples, and C. lusitaniae (3/43) and C. guilliermondii (1/43) were present in the controls. After RT-PCR was applied, Candida spp. were found to be present in 67.4 % (31/46) and 79.1 % (34/43) of patient and control samples investigated, respectively. PCR detection of C. albicans and C. parapsilosis revealed only a low sensitivity and specificity of 67.4 % and 41.9 %, respectively. Our data do not support the use of Candida RT-PCR for sensitive and specific diagnosis of mammary candidiasis.

Comparison of the BD MAX® Enteric Bacterial Panel assay with conventional diagnostic procedures in diarrheal stool samples.

Although infectious diarrhea is one of the most predominant diseases around the world, the identification of the causative microorganism is still challenging. The aim of this study was the evaluation of the BD MAX® Enteric Bacterial Panel assay in comparison to conventional diagnostic procedures concerning the detection of the enteric pathogens Salmonella spp., Campylobacter spp., Shigella spp., and Shiga toxin-producing Escherichia coli. For this purpose, 971 prospectively collected stool samples were evaluated. Utilization of the BD MAX Enteric Bacterial Panel elevated the overall detection rate from 5.26 % to 8.06 %. The positive percent agreement of the BD MAX Enteric Bacterial Panel assay and stool culture or enzyme immunoassay was 0.97 for Campylobacter spp., 0.75 for Salmonella spp., 1.00 for Shigella spp., and 0.88 for Shiga toxins. Furthermore, a negative percent agreement of 0.98 for Campylobacter spp., 0.99 for Salmonella spp., 0.99 for Shigella spp., and 0.99 for Shiga toxins has been demonstrated. This study highlighted the superior detection rate of molecular assays compared to conventional diagnostic procedures.