Efflux Pump, the Masked Side of ß-Lactam Resistance in Klebsiella pneumoniae Clinical Isolates

International audienceBACKGROUND: Beta-lactamase production and porin decrease are the well-recognized mechanisms of acquired beta-lactam resistance in Klebsiella pneumoniae isolates. However, such mechanisms proved to be absent in K. pneumoniae isolates that are non susceptible to cefoxitin (FOX) and susceptible to amoxicillin+clavulanic acid in our hospital. Assessing the role of efflux pumps in this beta-lactam phenotype was the aim of this study. METHODOLOGY/FINDINGS: MICs of 9 beta-lactams, including cloxacillin (CLX), and other antibiotic families were tested alone and with an efflux pump inhibitor (EPI), then with both CLX (subinhibitory concentrations) and EPI against 11 unique bacteremia K. pneumoniae isolates displaying the unusual phenotype, and 2 ATCC strains. CLX and EPI-dose dependent effects were studied on 4 representatives strains. CLX MICs significantly decreased when tested with EPI. A similar phenomenon was observed with piperacillin+tazobactam whereas MICs of the other beta-lactams significantly decreased only in the presence of both EPI and CLX. Thus, FOX MICs decreased 128 fold in the K. pneumoniae isolates but also 16 fold in ATCC strain. Restoration of FOX activity was CLX dose-dependent suggesting a competitive relationship between CLX and the other beta-lactams with regard to their efflux. For chloramphenicol, erythromycin and nalidixic acid whose resistance was also due to efflux, adding CLX to EPI did not increase their activity suggesting differences between the efflux process of these molecules and that of beta-lactams. CONCLUSION: This is the first study demonstrating that efflux mechanism plays a key role in the beta-lactam susceptibility of clinical isolates of K. pneumoniae. Such data clearly evidence that the involvement of efflux pumps in beta-lactam resistance is specially underestimated in clinical isolates

Molecular characterization of MRSA collected during national surveillance between 2008 and 2019 in the Netherlands

Background.Although the Netherlands is a country with a low endemic level, methicillin-resistant Staphylococcus aureus (MRSA) poses a significant health care problem. Therefore, high coverage national MRSA surveillance has been in place since 1989. To monitor possible changes in the type-distribution and emergence of resistance and virulence, MRSA isolates are molecularly characterized.Methods.All 43,321 isolates from 36,520 persons, collected 2008-2019, were typed by multiple-locus variable number tandem repeats analysis (MLVA) with simultaneous PCR detection of the mecA, mecC and lukF-PV genes, indicative for PVL. Next-generation sequencing data of 4991 isolates from 4798 persons were used for whole genome multi-locus sequence typing (wgMLST) and identification of resistance and virulence genes.Results.We show temporal change in the molecular characteristics of the MRSA population with the proportion of PVL-positive isolates increasing from 15% in 2008-2010 to 25% in 2017-2019. In livestock-associated MRSA obtained from humans, PVL-positivity increases to 6% in 2017-2019 with isolates predominantly from regions with few pig farms. wgMLST reveals the presence of 35 genogroups with distinct resistance, virulence gene profiles and specimen origin. Typing shows prolonged persistent MRSA carriage with a mean carriage period of 407 days. There is a clear spatial and a weak temporal relationship between isolates that clustered in wgMLST, indicative for regional spread of MRSA strains.Conclusions.Using molecular characterization, this exceptionally large study shows genomic changes in the MRSA population at the national level. It reveals waxing and waning of types and genogroups and an increasing proportion of PVL-positive MRSA.A group of bacteria that cause difficult-to-treat infections in humans is methicillin-resistant Staphylococcus aureus (MRSA). The aim of this study was to monitor changes in the spread of MRSA, their disease causing potential and resistance to antibiotics used to treat MRSA infections. MRSA from patients and their contacts in the Netherlands were collected over a period of 12 years and characterized. This revealed new types of MRSA emerged and others disappeared. An increasing number of MRSA produces a protein called PVL toxin, enabling MRSA to cause more severe infections. Also, some people appear to carry MRSA without any disease for more than a year. These findings suggest an increasing disease potential of MRSA and possible unnoticed sources of infection. Consequently, it is important to maintain monitoring of these infections to minimize MRSA spread.Schouls et al. characterize 43,321 methicillin-resistant Staphylococcus aureus (MRSA) isolates obtained between 2008 and 2019 in the Netherlands. Genomic changes occur in the MRSA population, with increases in the proportion of PVL-positive MRSA.Molecular basis of bacterial pathogenesis, virulence factors and antibiotic resistanc

Triathlon in Alphen a/d Rijn August 1991. Study on health effects and water quality

This report describes an epidemiological study on health effects of participation in a triathlon and their relation to water quality. illness was reported more frequently by participants than by controls. Gastro-instestinal symptoms and head-aches were predominant ; respiratory, skin and mucosal symptoms were also reported. The risk of acquiring highly credible gastro-enteritis was significantly higher for participants (28/439) than for controls (1/217) ; odds ratio 14,7. Prolonged exposure to water of the Zegerplas tended to result in a higher risk of acquiring gastro-enteritis. These findings, together with the absence of an effect of other possible sources, led to the conclusion that the water of the Zegerplas was the most likely source of infection. Electron microscopic examination of faeces showed the presence of viruses in 6/12 participants. Because of the low number of samples and the absence of control samples, no definitive conclusions can be drawn, but viral aetiology of the gastro-intestinal symptoms is likely. Microbiological investigation showed that the faecal pollution of the Zegerplas at the time of the triathlon was considerable (thermotolerant coliforms 750/100mL ; faecal streptococci 20/100mL (geometric mean counts)) ; the source of pollution was the effluent discharge of the waste water treatment plant.GHIGGD Rijnstree

Prevention of Congenital Syphilis ; economic evaluation of data supplied by the regional Public Health laboratoria

Doel: Vaststellen van de programmakosten, monetaire baten en gewonnen levensjaren, verbonden aan het screeningsprogramma van zwangeren op syfilis, gebruik makend van gegevens over serologische testresultaten in de Streeklaboratoria. Data & Methode: We gebruiken twee typen gegevens: (i) Aantallen en resultaten van serologische testen op syfilis (TPHA, VDRL, RPR, FTA) bij zwangeren in de 2e helft van 1991 en in 1992 in de Nederlandse Streeklaboratoria ; (ii) Relevante informatie over de kosten van testen, gezondheidszorg en onderwijs en de levensverwachting. Het economische evaluatie-model dat wij hanteren is een uitgebreide versie van het Noorse epidemiologische model dat specifiek is ontwikkeld voor syfilis tijdens de zwangerschap en preventie van congenitale syfilis. Het evaluatie-model koppelt het epidemiologische model met economische informatie. Naast de directe kosten van het screeningsprogramma zoals testen, behandeling en na-controle worden in het model monetaire baten bepaald van voorkomen gezondheidszorg voor geinfecteerde en te vroeg geboren kinderen en van voorkomen zorg en speciaal onderwijs voor lichamelijk en geestelijk gehandicapten. Tot slot worden in het model de door het screeningsprogramma gewonnen levensjaren berekend wegens het voorkomen van perinatale sterfte en verkorte levensverwachting van gehandicapten (berekening van gewonnen levensjaren op basis van resterende levensverwachting). De gegevensverzameling is bruikbaar voor de analyse van de effectiviteit van het screeningsprogramma en continuering ervan is daarom van belang. (ii) Op basis van de hier gebruikte gegevens en het Noorse epidemiologische model is de screening ter preventie van congenitale syfilis een kosten-effectief programma en is het aan te bevelen de screening voort te zetten. (iii) Voor een definitieve berekening van de kosten en baten van het screeningsprogramma is het nodig het gebruikte evaluatie-model verder te ontwikkelen en te valideren.The objective of this investigation was assessment of the program costs, monetary benefits and life years gained, connected to the screeningsprogram for syphilis during pregnancy, using laboratory data on serological test results. Two types of data were used: (i) Numbers and results of serological syphilis tests (TPHA, VDRL, RPR, FTA) for pregnant women in the second half of 1991 and in 1992, supplied by the regional Public Health laboratoria ; (ii) Relevant information on the costs of tests, health care utilisation and education and the life expectancy. The applied economic evaluation-model is an extension of the Norwegian epidemiological model that has specifically been developed for syphilis during pregancy and prevention of congenital syphilis. The evaluation-model links the epidemiological model with economic information. Next to the direct costs of the screeningsprogram such as testing, treatment and follow-up the model assesses the monetary benefits of preventing health care for infected and prematurely born children and of preventing care and special education of mentally retarded and physically disabled persons. Further, the model incorporates the years of life gained by the screeningsprogram due to preventing perinatal mortality and shortened life expectancy of handicaped persons (life years gained are calculated using the remaining life expectancy at time of death). The data-gathering is useful for analysing the effectivity of the screeningsprogram, analogous data-gathering in the future is therefore important. (ii) On the basis of our data and the Norwegian epidemiological model, the screening for preventing congenital syphilis is estimated to be a cost-effective program and should therefore be continued. (iii) For a final calculation of the cost-effectiveness of the screeningsprogram it is necessary to further develop the evaluation-model and to validate it.HI

Prevention of congenital syphilis ; a study into the question whether national screening has to be continued or not

This study summarizes clinical, laboratory and epidemiological aspects of syphilis and congenital syphilis. An outline is given of an economic evaluation of the programme for the prevention of congenital syphilis. figures available in the Netherlands were used in a previousluy published model for analysis of costs and benefits of the screening for syphilis in pregnancy. Although the costs of testing the individual women are low, the costs of a life-year gained were considerable for the studied year 1988 (48.800 Dutch guilders, about 24.000 U.S. dollars). The incidence of syphilis in pregnancy has not dropped to such a level that the Netherlands could do without any programme for the control of syphilis in pregnancy. Therefore abandoning the current programme in the Netherlands should not be considered in the near future.GH