- Volume 66, Issue 7, 2017
Volume 66, Issue 7, 2017
- Microbial Epidemiology
-
-
-
Candidaemia in a tertiary care academic hospital in Italy. The impact of C. parapsilosis complex on the species distribution and antifungal susceptibility
More LessPurpose. To analyse the species distribution and the susceptibility profiles to the major antifungal agents of Candida isolated from bloodstream infections (BSIs) in both intensive care units (ICUs) and non-ICU wards in a tertiary care hospital in Italy from 2010 until 2015.
Methodology. Episodes of Candida BSI were recorded in a retrospective observational cohort study. Yeasts were isolated from both blood and intravascuIar devices (IVDs) and their susceptibility to antifungal drugs was tested using the microdilution method.
Results. 514 Candida BSIs were evidenced and 19 % of these episodes were associated with the presence of an IVD. The trend of the general incidence increased significantly throughout the study period, ranging from 1.42 to 3.63 (mean 2.52) episodes/1000 admissions. The incidence of Candida BSIs and IVD-associated candidaemia was significantly higher in ICUs relative to the other wards. The most frequently isolated species were C. albicans and C. parapsilosis complex, with the latter presenting a significant increased trend of isolation. C. parapsilosis complex was most frequently involved in IVD-related candidaemia, coinfections and late recurrent infections. Furthermore, the MIC50s of C. parapsilosis complex were significantly enhanced for echinocandins compared to the MIC50s for the same drugs and the other yeasts, while the MIC50s of C. albicans for amphotericin B showed a significant increase during the study period, ranging from 0.1 to 0.5 µg ml−1.
Conclusions. A progressively enhanced incidence of Candida BSIs, a relatively high impact of C. parapsilosis complex and changes in the susceptibility profiles of the isolated yeasts were evidenced during the observation period.
-
-
-
-
Molecular epidemiology of beta-lactamase producing nosocomial Gram-negative pathogens from North and South Indian hospitals
More LessPurpose. Resistant Gram-negative bacterial (GNB) infections, apart from tremendously escalating the cost of treatment, are a cause for substantial morbidity and mortality among hospitalized patients. Such bacteria are rapidly acquiring resistance to many antimicrobial agents, especially the beta-lactams which are the most frequently prescribed antimicrobials in hospital and community patient care settings, and now also to colistin; a last-line drug to treat infections with such bacteria. The greatest threat to antimicrobial treatment is the production of metallo beta-lactamases, and plasmid-mediated serine carbapenemases.
Methodology. We conducted a two-year study to observe the pattern of beta-lactamase enzyme production (extended spectrum beta-lactamases (ESBLs), AmpC and carbapenemases) among the nosocomial GNB isolated from intensive care units (ICUs) of North and South Indian hospitals. A total of 761 non-duplicate GNB were included in the study from North (554; 73 %) and South India (207; 27 %). All strains were subjected to Clinical and Laboratory Standards Institute (CLSI) recommended screening tests for detection of beta-lactamase production, followed by polymerase chain reaction (PCR)-based detection of clinically important beta-lactamase genes mediating resistant phenotypes among these isolates.
Results. Out of the 761 GNB, Acinetobacter spp., Klebsiella spp., Pseudomonas spp., Enterobacter spp. and others were 27, 23 , 21 , 17 , 5 and 7 % respectively. A high prevalence of ESBL was found across all genera in these strains. The carbapenem resistance was higher in North than in South Indian GNB. The level of AmpC production was comparatively lower in both North and South Indian strains.
Conclusion. Beta-lactamases showed tremendous variation in geographic distribution. Thus, their detection and characterization is important from a clinical-epidemiological, laboratory and infection control point of view. Knowledge of this epidemiology can predict the empiric antimicrobial treatment.
-
-
-
A high prevalence of beak and feather disease virus in non-psittacine Australian birds
Purpose. Beak and feather disease virus (BFDV) is a circovirus and the cause of psittacine beak and feather disease (PBFD). This disease is characterized by feather and beak deformities and is a recognized threat to endangered Psittaciformes (parrots and cockatoos). The role that non-psittacine birds may play as reservoirs of infection is unclear. This study aimed to begin addressing this gap in our knowledge of PBFD.
Methodology. Liver samples were collected from birds presented to the Australian Wildlife Health Centre at Zoos Victoria’s Healesville Sanctuary for veterinary care between December 2014 and December 2015, and tested for BFDV DNA using polymerase chain reaction coupled with sequencing and phylogenetic analyses.
Results/Key findings. Overall BFDV was detected in 38.1 % of 210 birds. BFDV was detected at high prevalence (56.2 %) in psittacine birds, in the majority of cases without any observed clinical signs of PBFD. We also found that BFDV was more common in non-psittacine species than previously recognized, with BFDV detected at 20.0 % prevalence in the non-psittacine birds tested, including species with no clear ecological association with psittacines, and without showing any detectable clinical signs of BFDV infection.
Conclusion. Further research to determine the infectivity and transmissibility of BFDV in non-psittacine species is indicated. Until such work is undertaken the findings from this study suggest that every bird should be considered a potential carrier of BFDV, regardless of species and clinical presentation. Veterinary clinics and wildlife rehabilitation facilities caring for birds that are susceptible to PBFD should reconsider biosecurity protocols aimed at controlling BFDV.
-
-
-
Evolutionary changes in the capsid P2 region of Australian strains of the norovirus GII.Pe_GII.4
More LessPurpose. The protruding (P) 2 region of the norovirus capsid is thought to include hypervariable sites involved in receptor binding. This study examines the changes that occurred in the P2 region of GII.Pe_GII.4 norovirus in the course of its evolution from a precursor phase (2008–2009), to an intermediate phase (2010) and finally to an epidemic phase (2012–2015).
Methodology. Twenty-two P2 region amino acid (aa) sequences (166 aa long) from all phases of the evolution of the virus were compared and the changes analysed.
Results/key findings. Twenty sites in the P2 region underwent aa change and of these, 10 corresponded to previously proposed hypervariable sites and 10 to novel hypervariable sites. It was notable that aa changes at two sites, X and Y, only emerged as the epidemic phase progressed. 3D computer modelling of the P2 region indicated that neither X nor Y were in the uppermost ‘crown’, but further down in the ‘neck’ portion. The location of X and Y and the nature of aa change at Y suggest these sites were important in enhancing the structural integrity of the capsid, which in turn may have facilitated the longer term viability of the virus.
Conclusion. The current study helps establish the validity of previously proposed hypervariable sites in the P2 region as well as indicating new ones. It also provides quantitative and qualitative data on how these sites changed over the evolutionary history of a particular norovirus strain.
-
-
-
Minimum inhibitory concentration distributions for first- and second-line antimicrobials against Mycobacterium tuberculosis
More LessWe report the range of minimum inhibitory concentrations for six antimicrobial drugs in 228 clinical Mycobacterium tuberculosis (MTB) isolates from three distinct groups of patients (unselected patients, patients at high risk of drug-resistant TB and HIV-positive patients) in Lima, Peru. These data highlight the challenges of and discriminatory characteristics required for MTB drug susceptibility testing.
-
- One Health
-
-
-
Characterization of high level ampicillin- and aminoglycoside-resistant enterococci isolated from non-hospital sources
Purpose. High level ampicillin- and aminoglycoside-resistant enterococci are being increasingly reported from non-hospital sources. This study was carried out to characterize these strains from non-hospital sources in Nigeria.
Methodology. A collection of Enterococcus faecium isolated from vegetables, soil, farm animals and manure and observed to be resistant to ampicillin (n=63) and gentamicin (n=37) discs, were screened for resistance to high levels of ampicillin and aminoglycoside using E-test strips. Putative high level ampicillin- and aminoglycoside-resistant strains were screened for pbp5 and aminoglycoside modifying enzyme genes, respectively, by PCR. The C-terminal region of the amplified pbp5 gene was also sequenced.
Results. Five (5/63) and thirty-five (35/37) of the ampicillin- and aminoglycoside-resistant strains were identified as high level ampicillin- and aminoglycoside-resistant E. faecium strains, respectively, based on the MIC results. The amplified pbp5 gene from the high level ampicillin-resistant isolates displayed 96–99 % nucleotide sequence similarity with the reference strains and three novel insertions (500Glu→Leu, 502Asp→Arg and 614Ile→Phe) in the amino acid sequence. Aminoglycoside modifying enzyme genes aac(6′)-Ie-aph(2″) (100 %), aph(2′)- Ic (88.8 %), aph(3′)- IIIa (90 %) and ant(4′)-Ia (40 %) were detected among the high level aminoglycoside-resistant isolates.
Conclusion. This is the first report on the characterization of high level ampicillin- and aminoglycoside-resistant Enterococcus faecium among animals and vegetables in Nigeria. The results show that non-hospital sources can constitute a reservoir for potential dissemination of these strains and genes to humans via the food chain or by direct contact.
-
-
- Pathogenicity and Virulence/Host Response
-
-
-
Mycobacterium tuberculosis hypoxic response protein 1 (Hrp1) augments the pro-inflammatory response and enhances the survival of Mycobacterium smegmatis in murine macrophages
Purpose. The DosR/DosS two-component regulatory system of Mycobacterium tuberculosis regulates the expression of numerous genes under stress conditions and is important for the long-term survival of M. tuberculosis in the host. The rv2626c gene of M. tuberculosis is one of the most strongly induced transcripts of the dormancy regulon. This study focused on the immunological effects and possible function of Rv2626c in maintaining mycobacterial survival under various stress conditions.
Methodology. We heterologously expressed the Rv2626c protein in Mycobacterium smegmatis by constructing a recombinant strain Ms_rv2626c. The viability of Ms_rv2626c was evaluated both in vivo and ex vivo. Different stress conditions, including acidified sodium nitrite, malachite green, low pH, SDS and lysozyme, were used to evaluate the effect of Rv2626c on bacterial resistance. An in vitro assay using a macrophage infection model was utilized to investigate the potential effect of Rv2626c to alter the immune response of host cell and its associated pathways. The effect of Rv2626c on cell necrosis was also explored.
Results. The expression of Rv2626c-enhanced M. smegmatis survival under hypoxia and nitric oxide stress in vitro, and this enhancement was maintained within macrophages and in mouse tissues. In addition, macrophages infected with M. smegmatis expressing Rv2626c showed significantly higher interleukin-1β (IL-1β), IL-6, tumour necrosis factor-α (TNF-α) and inducible nitric oxide synthase (iNOS) expression, as well as a higher level of cell necrosis, compared with the control.
Conclusion. M. tuberculosis protein Rv2626c plays a significant role in stimulating macrophages to provoke a pro-inflammatory response and in mycobacterial survival during infection.
-
-
-
-
Quantitative and structural analyses of the in vitro and ex vivo biofilm-forming ability of dermatophytes
Raimunda Sâmia Nogueira Brilhante, Edmilson Emanuel Monteiro Correia, Glaucia Morgana de Melo Guedes, Vandbergue Santos Pereira, Jonathas Sales de Oliveira, Silviane Praciano Bandeira, Lucas Pereira de Alencar, Ana Raquel Colares de Andrade, Débora de Souza Collares Maia Castelo-Branco, Rossana de Aguiar Cordeiro, Adriana de Queiroz Pinheiro, Lúcio Jackson Queiroz Chaves, Waldemiro de Aquino Pereira Neto, José Júlio Costa Sidrim and Marcos Fábio Gadelha RochaPurpose. The aim of this study was to evaluate the in vitro and ex vivo biofilm-forming ability of dermatophytes on a nail fragment.
Methodology. Initially, four isolates of Trichophyton rubrum, six of Trichophyton tonsurans, three of Trichophyton mentagrophytes, ten of Microsporum canis and three of Microsporum gypseum were tested for production biomass by crystal violet assay. Then, one strain per species presenting the best biofilm production was chosen for further studies by optical microscopy (Congo red staining), confocal laser scanning (LIVE/DEAD staining) and scanning electron (secondary electron) microscopy.
Results. Biomass quantification by crystal violet assay, optical microscope images of Congo red staining, confocal microscope and scanning electron microscope images revealed that all species studied are able to form biofilms both in vitro and ex vivo, with variable density and architecture. M. gypseum, T. rubrum and T. tonsurans produced robust biofilms, with abundant matrix and biomass, while M. canis produced the weakest biofilms compared to other species.
Conclusion. This study sheds light on biofilms of different dermatophyte species, which will contribute to a better understanding of the pathophysiology of dermatophytosis. Further studies of this type are necessary to investigate the processes involved in the formation and composition of dermatophyte biofilms.
-
-
-
Hyperinvasiveness and increased intercellular spread of Listeria monocytogenes sequence type 1 are independent of listeriolysin S, internalin F and internalin J1
More LessPurpose. Listeria monocytogenes is a genetically heterogeneous species, which is divided into evolutionary lineages and clonal complexes (CCs). Not all L. monocytogenes isolates are equally likely to cause disease, with CC1, and in particular sequence type (ST) 1, being the most prevalent complex in human and ruminant infections and more specifically in neurolisteriosis. While the major factors that determine neurotropism are unknown, the L. monocytogenes CC1 strains harbour listeriolysin S (lls) and particular alleles of internalin (inl) F and inlJ, which are not present in CCs commonly isolated from food and the environment. The aim of this study was to analyse the role of these factors in cellular infection.
Methodology. A ST1 field strain (JF5203) from CC1 isolated from a bovine rhombencephalitis case was used to create deletion mutants. These were tested alongside the parental strain and EGD-e (CC9), in different culture models representing L. monocytogenes targets (neurons, microglia, placenta, intestine and macrophages). The phenotype was assessed by quantification of c.f.u. from cell lysates and immunofluorescence analysis.
Results. Compared to EGD-e, the ST1 strain JF5203 was hyperinvasive and exhibited increased intercellular spread. However, deletion of llsB, inlF or inlJ1, had no significant effect on infection or growth in the culture models tested.
Conclusion. Our results underline the importance of using relevant clinical strains when investigating L. monocytogenes virulence. We show that despite the association with CC1, llsB, inlF and inlJ1 are not involved in the hyperinvasiveness and efficient intercellular spread of ST1 in various cell types.
-
- Prevention and Therapy
-
-
-
Comparative analysis of the genomes of clinical isolates of Mycobacterium avium subsp. hominissuis regarding virulence-related genes
More LessPurpose. Mycobacterium avium subsp. hominissuis is a member of the M. avium complex, a heterogeneous group of bacteria that cause lung infection in immunocompetent patients or disseminated infection in patients with immunosuppression. The bacteria belonging to this complex have variable virulence, depending on the strain considered, and therefore a representative of the most common clinical phenotype was analysed.
Methodology. The genomic sequences of four M. avium subsp. hominissuis isolates obtained from clinical specimens were completed. Mav101, Mav100 and MavA5 were isolated from the blood of patients with AIDS. MavA5 was disseminated from the lung, while Mav3388 was isolated from the lungs of a patient with chronic lung disease. The sequences were annotated using the published Mav104 genome as a blueprint. Functional and virulence analyses of the sequences were carried out. Mice studies comparing the virulence of the strains were performed.
Results. Findings showed that while Mav101 was very similar to Mav104, there were numerous differences between Mav104 and the remaining strains at nucleotide and predicted protein levels. The presence of genes associated with biofilm formation and several known virulence-related genes were sometimes differentially present among the isolates, suggesting overlapping functions by different genetic determinants.
Conclusions. The sequences provided important information about M. avium heterogenicity and evolution as a pathogen. The limitation is the lack of understanding on possible overlapping functions of genes/proteins.
-
-
-
-
Chemical composition and cytotoxicity of extracts of marjoram and rosemary and their activity against Sporothrix brasiliensis
Purpose. Motivated by increasing reports of antifungal resistance in human and animal sporotrichosis, this study evaluated the chemical composition, cytotoxicity and anti-Sporothrix brasiliensis activity of extracts of marjoram (Origanum majorana) and rosemary (Rosmarinus officinalis).
Methodology. Ten (INF10) and 60 min (INF60) infusions, a decoction and a hydroalcoholic extract (HAE, 70 %) were prepared from both plants (10 % w/v). The extract composition was analysed by liquid chromatography/mass spectrometry and the cytotoxicity was evaluated using a colorimetric assay in canine and feline kidney cells. Using a broth microdilution assay (CLSI M38-A2) adapted to the extracts, 30 Sporothrix brasiliensis isolates from dogs, cats and humans, and one Sporothrix schenckii were tested.
Results/Key findings. The predominant phenolic compounds found in all extracts were 4-hydroxybenzoic acid, caffeic acid and chlorogenic acid. Luteolin was also one of the predominant compounds, but only in the HAE of marjoram. Extracts of marjoram maintained cell viability in concentrations up to 2.5 mg ml−1 for the feline cell line and up to 10 mg ml−1 for the canine cell line, whereas in rosemary, the cell viability for both kidney lines was maintained with concentrations up to 5 mg ml−1. The activity of rosemary extracts was low or absent. Among the marjoram extracts, HAE was highlighted and had fungistatic activity against Sporothrix brasiliensis (MIC5040 mg ml−1), including in all itraconazole-resistant isolates. S. schenckii sensu stricto was sensitive to marjoram extracts (MIC/MFC ≤5 mg ml−1), with the exception of INF10.
Conclusion. These findings support the potential usefulness of the HAE of marjoram in the treatment of sporotrichosis.
-
Volumes and issues
-
Volume 73 (2024)
-
Volume 72 (2023 - 2024)
-
Volume 71 (2022)
-
Volume 70 (2021)
-
Volume 69 (2020)
-
Volume 68 (2019)
-
Volume 67 (2018)
-
Volume 66 (2017)
-
Volume 65 (2016)
-
Volume 64 (2015)
-
Volume 63 (2014)
-
Volume 62 (2013)
-
Volume 61 (2012)
-
Volume 60 (2011)
-
Volume 59 (2010)
-
Volume 58 (2009)
-
Volume 57 (2008)
-
Volume 56 (2007)
-
Volume 55 (2006)
-
Volume 54 (2005)
-
Volume 53 (2004)
-
Volume 52 (2003)
-
Volume 51 (2002)
-
Volume 50 (2001)
-
Volume 49 (2000)
-
Volume 48 (1999)
-
Volume 47 (1998)
-
Volume 46 (1997)
-
Volume 45 (1996)
-
Volume 44 (1996)
-
Volume 43 (1995)
-
Volume 42 (1995)
-
Volume 41 (1994)
-
Volume 40 (1994)
-
Volume 39 (1993)
-
Volume 38 (1993)
-
Volume 37 (1992)
-
Volume 36 (1992)
-
Volume 35 (1991)
-
Volume 34 (1991)
-
Volume 33 (1990)
-
Volume 32 (1990)
-
Volume 31 (1990)
-
Volume 30 (1989)
-
Volume 29 (1989)
-
Volume 28 (1989)
-
Volume 27 (1988)
-
Volume 26 (1988)
-
Volume 25 (1988)
-
Volume 24 (1987)
-
Volume 23 (1987)
-
Volume 22 (1986)
-
Volume 21 (1986)
-
Volume 20 (1985)
-
Volume 19 (1985)
-
Volume 18 (1984)
-
Volume 17 (1984)
-
Volume 16 (1983)
-
Volume 15 (1982)
-
Volume 14 (1981)
-
Volume 13 (1980)
-
Volume 12 (1979)
-
Volume 11 (1978)
-
Volume 10 (1977)
-
Volume 9 (1976)
-
Volume 8 (1975)
-
Volume 7 (1974)
-
Volume 6 (1973)
-
Volume 5 (1972)
-
Volume 4 (1971)
-
Volume 3 (1970)
-
Volume 2 (1969)
-
Volume 1 (1968)