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Int J Med Microbiol [journal]
- Relevance of Campylobacter to public health-The need for a One Health approach. [JOURNAL ARTICLE]
- Int J Med Microbiol 2014 Aug 30.
Campylobacter species belong to the most important foodborne bacteria which cause gastroenteritis in humans in both developed and developing countries. With increasing reporting rates, the public awareness towards Campylobacter infections is growing continuously. This strengthens the necessity to establish intervention measures for prevention and control of thermophilic Campylobacter spp. along the food chain, as in particular poultry and poultry meat represent a major source of human infections. An interdisciplinary One Health approach and a combined effort of all stakeholders are necessary to ultimately reduce the burden of campylobacteriosis cases in humans. Numerous studies point out, however, that at present a complete elimination of Campylobacter in the food chain is not feasible. The present aim should therefore be to establish control measures and intervention strategies to minimize the occurrence of Campylobacter spp. in livestock (e.g. poultry flocks) and to reduce the quantitative Campylobacter burden in animals and foods. To this end, a combination of intervention methods at different stages of the food chain appears most promising. That has to be accompanied by targeted consumer advice and education campaigns to raise the awareness towards Campylobacter infections.
- "One Health" - Linking human, animal and environmental health. [EDITORIAL]
- Int J Med Microbiol 2014 Aug 30.
- Arcobacter butzleri induces a pro-inflammatory response in THP-1 derived macrophages and has limited ability for intracellular survival. [JOURNAL ARTICLE]
- Int J Med Microbiol 2014 Sep 6.
Recent case reports have identified Arcobacter (A.) butzleri to be another emerging pathogen of the family Campylobacteraceae causing foodborne diseases. However, little is known about its interaction with the human immune system. As macrophages act as first defense against bacterial infections, we studied for the first time the impact of A. butzleri on human macrophages using THP-1 derived macrophages as an in vitro infection model. Our investigations considered the inflammatory response, intracellular survival and activation of caspases as potential virulence mechanisms employed by A. butzleri. Induction of IL-1α, IL-1β, IL-6, IL-8, IL-12β and TNFα demonstrated a pro-inflammatory response of infected macrophages towards A. butzleri. gentamycin protection assays revealed the ability of A. butzleri strains to survive and resist the hostile environment of phagocytic immune cells for up to 22h. Moreover, initial activation of intitiator- (CASP8) as well as effector caspases (CASP3/7) was observed without the onset of DNA damage, suggesting a potential counter regulation. Intriguingly, we recognized distinct strain specific differences in invasion and survival capabilities. This suggests the existence of isolate dependent phenotype variations and different virulence potentials as known for other intestinal pathogens such as Salmonella enterica ssp.
- Evaluation of molecular methods to discriminate the closely related species Vibrio fluvialis and Vibrio furnissii. [JOURNAL ARTICLE]
- Int J Med Microbiol 2014 Sep 9.
Vibrio furnissii and Vibrio fluvialis are two closely related species which are regarded as emerging human pathogens. Human infections have been mainly associated with consumption of seafood or drinking of contaminated water. V. furnissii strains can be distinguished from V. fluvialis by their ability to produce gas from fermentation of carbohydrates. In this study, we compare two phenotypic (biochemical testing and matrix-assisted laser desorption/ionisation time of flight mass spectrometry, MALDI-TOF MS) and three genotypic techniques (rpoB sequencing, conventional PCR and real-time PCR) for determination of the two species. The methods were evaluated on a collection of 42 V. furnissii and 32 V. fluvialis strains, which were isolated from marine environments and from animals intended for food production. Four of the applied methods allowed the unambiguous discrimination of the two species, while the biochemical testing was the least reliable technique, due to a high variation in the phenotype of gas production from carbohydrates. In view of the One Health concept reliable diagnostic techniques are a prerequisite for preventive public health measurements, as pathogens isolated from animals can cross species borders and methods for detection of sources, reservoirs and ways of transmission of pathogenic bacteria are indispensable for the prevention of infectious diseases in humans and animals.
- Pseudomonas quinolone signalling system: A component of quorum sensing cascade is a crucial player in the acute urinary tract infection caused by Pseudomonas aeruginosa. [JOURNAL ARTICLE]
- Int J Med Microbiol 2014 Sep 1.
Pseudomonas aeruginosa is an opportunistic pathogen which employs quorum sensing system to regulate several genes required for its survival and pathogenicity within the host. Besides acylhomoserine lactone (AHL) mediated las and rhl systems, this organism possesses Pseudomonas quinolone signalling (PQS) system based on alkyl quinolone signal molecules. The quinolone system represents another layer of sophistication in the complex quorum sensing cascade. Therefore, in the present study, we evaluated the contribution of the PQS system in the establishment of acute urinary tract infection (UTI) in the mouse model. For this, wild-type parent strain of P. aeruginosa MPAO1 and its isogenic single transposon mutant strains pqsH and pqsA were employed to induce UTI in mice. PQS molecules in the tissue homogenates of mice were detected by high performance thin layer chromatography (HP-TLC) method. Virulence of strains was assessed in terms of bacteriological count, histopathological lesions in the renal and bladder tissue and generation of pathological index markers like reactive nitrogen intermediates and malondialdehyde. HP-TLC analysis showed presence of PQS molecules in the renal and bladder tissue of mice infected with MPAO1 while no PQS was detected in case of pqsH and pqsA mutant strains. Results indicated that MPAO1 possessing fully functional PQS biosynthetic genes was highly virulent and caused acute pyelonephritis with severe inflammation and tissue destruction. On the contrary, significant reduction in the log count, mild tissue damage and declined levels of pathological markers were observed in mice infected with mutant strains as compared to MPAO1. Further among mutants, all these parameters were maximally impaired in the pqsA mutant in which synthesis of alkyl quinolones was completely abolished due to the transposon mutation in respective gene. Virulence of the pqsH mutant strain was lesser than that of the MPAO1 but higher than pqsA mutant. In addition, the levels of locally generated pro- and anti-inflammatory cytokines were also found to be low in the renal homogenates of mice infected with the mutant strains. Further, supplementation of strains with PQS resulted in significant enhancement in the virulence as indicated by increased bacterial load, severe histopathological damage and enhanced levels of pro-inflammatory cytokines. These findings provide a new insight into the relevant importance of the Pseudomonas quinolone signalling system in the acute UTI caused by P. aeruginosa. This system can be a potential target for futuristic anti-infective approach against this organism.
- New patterns of methicillin-resistant Staphylococcus aureus (MRSA) clones, community-associated MRSA genotypes behave like healthcare-associated MRSA genotypes within hospitals, Argentina. [JOURNAL ARTICLE]
- Int J Med Microbiol 2014 Aug 12.
Methicillin-resistant Staphylococcus aureus (MRSA) burden is increasing worldwide in hospitals [healthcare-associated (HA)-MRSA] and in communities [community-associated (CA)-MRSA]. However, the impact of CA-MRSA within hospitals remains limited, particularly in Latin America. A countrywide representative survey of S. aureus infections was performed in Argentina by analyzing 591 clinical isolates from 66 hospitals in a prospective cross-sectional, multicenter study (Nov-2009). This work involved healthcare-onset infections-(HAHO, >48 hospitalization hours) and community-onset (CO) infections [including both, infections (HACO) in patients with healthcare-associated risk-factors (HRFs) and infections (CACO) in those without HRFs]. MRSA strains were genetically typed as CA-MRSA and HA-MRSA genotypes (CA-MRSAG and HA-MRSAG) by SCCmec- and spa-typing, PFGE, MLST and virulence genes profile by PCR. Considering all isolates, 63% were from CO-infections and 55% were MRSA [39% CA-MRSAG and 16% HA-MRSAG]. A significantly higher MRSA proportion among CO- than HAHO-S. aureus infections was detected (58% vs 49%); mainly in children (62% vs 43%). The CA-MRSAG/HA-MRSAG have accounted for 16%/33% of HAHO-, 39%/13% of HACO- and 60.5%/0% of CACO-infections. Regarding the epidemiological associations identified in multivariate models for patients with healthcare-onset CA-MRSAG infections, CA-MRSAG behave like HA-MRSAG within hospitals but children were the highest risk group for healthcare-onset CA-MRSAG infections. Most CA-MRSAG belonged to two major clones: PFGE-type N-ST30-SCCmecIVc-t019-PVL(+) and PFGE-type I-ST5-IV-SCCmecIVa-t311-PVL(+) (45% each). The ST5-IV-PVL(+)/ST30-IV-PVL(+) clones have caused 31%/33% of all infections, 20%/4% of HAHO-, 43%/23% of HACO- and 35%/60% of CACO- infections, with significant differences by age groups (children/adults) and geographical regions. Importantly, an isolate belonging to USA300-0114-(ST8-SCCmecIVa-spat008-PVL(+)-ACME(+)) was detected for the first time in Argentina. Most of HA-MRSAG (66%) were related to the Cordobes/Chilean clone-(PFGE-type A-ST5-SCCmecI-t149) causing 18% of all infections (47% of HAHO- and 13% of HACO-infections). Results strongly suggest that the CA-MRSA clone ST5-IV-PVL(+) has begun to spread within hospitals, replacing the traditional Cordobes/Chilean-HA-MRSA clone ST5-I-PVL(-), mainly in children. Importantly, a growing MRSA reservoir in the community was associated with spreading of two CA-MRSA clones: ST5-IV-PVL(+), mainly in children with HRFs, and ST30-IV-PVL(+) in adults without HRFs. This is the first nationwide study in Argentina providing information about the molecular and clinical epidemiology of CA-MRSA, particularly within hospitals, which is essential for designing effective control measures in this country and worldwide.
- Animals are key to human toxoplasmosis. [JOURNAL ARTICLE]
- Int J Med Microbiol 2014 Sep 10.
Toxoplasma gondii is an extremely sucessfull protozoal parasite which infects almost all mamalian species including humans. Approximately 30% of the human population worldwide is chronically infected with T. gondii. In general, human infection is asymptomatic but the parasite may induce severe disease in fetuses and immunocompromised patients. In addition, T. gondii may cause sight-threatening posterior uveitis in immunocompetent patients. Apart from few exceptions, humans acquire T. gondii from animals. Both, the oral uptake of T. gondii oocysts released by specific hosts, i.e. felidae, and of cysts persisting in muscle cells of animals result in human toxoplasmosis. In the present review, we discuss recent new data on the cell biology of T. gondii and parasite diversity in animals. In addition, we focus on the impact of these various parasite strains and their different virulence on the clinical outcome of human congenital toxoplasmosis and T. gondii uveitis.
- Production of biofilm by Candida and non-Candida spp. isolates causing fungemia: Comparison of biomass production and metabolic activity and development of cut-off points. [JOURNAL ARTICLE]
- Int J Med Microbiol 2014 Sep 1.
Biofilm production in Candida spp. can be studied by measuring the biomass produced after application of crystal violet stain or by measuring metabolic activity with XTT. Our study is the first in which crystal violet and XTT are compared to analyze the ability of clinically relevant Candida and non-Candida species to produce biofilm. We studied 577 isolates causing fungemia in 512 patients admitted from January 2007 to July 2013. Based on the biomass production measured by crystal violet and the metabolic activity measured by XTT, strains were divided into terciles to establish tentative cut-offs to classify isolates as being low, moderate, or high biofilm-forming and as having low, moderate, or high metabolic activity. Considerable variability in biofilm production and metabolic activity was found both between species and within species. C. tropicalis showed the highest biomass production, whereas C. glabrata showed the highest metabolic activity, and non-Candida species isolates showed the lowest metabolic activity (P<0.0023). The isolates were classified as low metabolic activity, moderate metabolic activity, and high metabolic activity according to their cut-offs by XTT (<0.097, 0.097-0.2, and >0.2) and as low biofilm-forming, moderate biofilm-forming, and high biofilm-forming according to their cut-offs by crystal violet (<0.44, 0.44-1.17, and >1.17). The overall categorical agreement between the procedures was 43.7%, which increased to >50% for C. albicans and C. parapsilosis. XTT and crystal violet are complementary procedures for the study of biofilm production.
- Influenza, a One Health paradigm-Novel therapeutic strategies to fight a zoonotic pathogen with pandemic potential. [JOURNAL ARTICLE]
- Int J Med Microbiol 2014 Aug 30.
Influenza virus is a paradigm for a pathogen that frequently crosses the species barrier from animals to humans, causing severe disease in the human population. This ranges from frequent epidemics to occasional pandemic outbreaks with millions of death. All previous pandemics in humans were caused by animal viruses or virus reassortants carrying animal virus genes, underlining that the fight against influenza requires a One Health approach integrating human and veterinary medicine. Furthermore, the fundamental question of what enables a flu pathogen to jump from animals to humans can only be tackled in a transdisciplinary approach between virologists, immunologists and cell biologists. To address this need the German FluResearchNet was established as a first nationwide influenza research network that virtually integrates all national expertise in the field of influenza to unravel viral and host determinants of pathogenicity and species transmission and to explore novel avenues of antiviral intervention. Here we focus on the various novel anti-flu approaches that were developed as part of the FluResearchNet activities.
- Capsular polysaccharide gene diversity of pneumococcal serotypes 6A, 6B, 6C, and 6D. [JOURNAL ARTICLE]
- Int J Med Microbiol 2014 Aug 17.
This study was performed to better understand the genetic diversity and evolutionary relatedness of pneumococcal serotypes 6A, 6B, 6C, and 6D. Multi-locus sequence typing (MLST) was performed for 160 serogroup 6 isolates from clinical specimens collected from children between 1991 and 2010. We identified 38 sequence types (STs) comprising five clonal complexes with 12 singletons. Although most STs were confined to a single serotype, some STs were shared by two serotypes, and one ST was shared by three serotypes. Many STs of serotype 6A showed genetic relatedness with those of serotype 6C or 6D in eBURST analysis. Five capsular polysaccharide (cps) genes - wchA, wciO, wciP, wzy, and wzx - were analysed in 74 isolates from our clinical samples and in 36 isolates from GenBank. There were several profiles and clades in each serotype on the analysis of the concatenated sequences of the five cps genes. Small genetic distances between serotypes 6A and 6B and between serotypes 6C and 6D were observed while serotype 6B with an indel sequence formed a distinct clade. When comparing the individual cps genes between the serotypes, there was also a high level of similarity in the wchA and wciO gene sequences between serotype 6C and serotype 6D. On the other hand, serotypes 6A and 6D had the most highly similar wzy and wzx gene sequences. The wzy sequences of serotype 6C were nearly identical (99.6%) to those of serotype 6A clade II strains. In conclusion, we revealed the diversity of the genetic background and cps sequences in each pneumococcal serotype of serogroup 6. Pneumococcal serotype diversity might be attributable to complex serial mutation and recombination events.