Selective Conditions for a Multidrug Resistance Plasmid Depend on the Sociality of Antibiotic Resistance
Antimicrobial Agents and Chemotherapy April 2016 V.60 N.4 P.2524-2527
Michael J. Bottery, A. Jamie Wood, and Michael A. Brockhurst
aDepartment of Biology, University of York, York, United Kingdom
bDepartment of Mathematics, University of York, York, United Kingdom
Multidrug resistance (MDR) plasmids frequently carry antibiotic resistance genes conferring qualitatively different mechanisms of resistance.
We show here that the antibiotic concentrations selecting for the RK2 plasmid in Escherichia coli depend upon the sociality of the drug resistance: the selection for selfish drug resistance (efflux pump) occurred at very low drug concentrations, just 1.3% of the MIC of the plasmid-free antibiotic-sensitive strain, whereas selection for cooperative drug resistance (modifying enzyme) occurred at drug concentrations exceeding the MIC of the plasmid-free strain.
Rapid Emergence and Evolution of Staphylococcus aureus Clones Harboring fusC-Containing Staphylococcal Cassette Chromosome Elements
Antimicrobial Agents and Chemotherapy April 2016 V.60 N.4 P.2359-2365
Sarah L. Baines, Benjamin P. Howden, Helen Heffernan, Timothy P. Stinear, Glen P. Carter, Torsten Seemann, Jason C. Kwong, Stephen R. Ritchie, and Deborah A. Williamson
aDoherty Applied Microbial Genomics, Department of Microbiology & Immunology, The University of Melbourne at The Doherty Institute for Infection and Immunity, Melbourne, Australia
bMicrobiological Diagnostic Unit Public Health Laboratory, Department of Microbiology & Immunology, The University of Melbourne at The Doherty Institute for Infection and Immunity, Melbourne, Australia
cInfectious Diseases Department, Austin Health, Melbourne, Australia
dInstitute of Environmental Science and Research, Wellington, New Zealand
eVictorian Life Sciences Computation Initiative, The University of Melbourne, Melbourne, Australia
fSchool of Medical Sciences, University of Auckland, Auckland, New Zealand
The prevalence of fusidic acid (FA) resistance among Staphylococcus aureus strains in New Zealand (NZ) is among the highest reported globally, with a recent study describing a resistance rate of approximately 28%.
Three FA-resistant S. aureus clones (ST5 MRSA, ST1 MSSA, and ST1 MRSA) have emerged over the past decade and now predominate in NZ, and in all three clones FA resistance is mediated by the fusC gene. In particular, ST5 MRSA has rapidly become the dominant MRSA clone in NZ, although the origin of FA-resistant ST5 MRSA has not been explored, and the genetic context of fusC in FA-resistant NZ isolates is unknown.
To better understand the rapid emergence of FA-resistant S. aureus, we used population-based comparative genomics to characterize a collection of FA-resistant and FA-susceptible isolates from NZ. FA-resistant NZ ST5 MRSA displayed minimal genetic diversity and represented a phylogenetically distinct clade within a global population model of clonal complex 5 (CC5) S. aureus.
In all lineages, fusC was invariably located within staphylococcal cassette chromosome (SCC) elements, suggesting that SCC-mediated horizontal transfer is the primary mechanism of fusC dissemination.
The genotypic association of fusC with mecA has important implications for the emergence of MRSA clones in populations with high usage of fusidic acid. In addition, we found that fusC was colocated with a recently described virulence factor (tirS) in dominant NZ S. aureus clones, suggesting a fitness advantage.
This study points to the likely molecular mechanisms responsible for the successful emergence and spread of FA-resistant S. aureus.
Mediterr J Hematol Infect Dis. 2012;4(1):e2012070. doi: 10.4084/MJHID.2012.070. Epub 2012 Nov 5.
1Divisione di Ematologia, Niguarda Ca’ Granda Hospital, Piazza Ospedale Maggiore 3 – 20162 Milano, Italy. Tel: 39-02-64442668.
Infectious complications have been known to be a major cause of morbidity and mortality in Chronic Lymphocytic Leukemia (CLL) patients who are prone to infections because of both the humoral immunodepression inherent to the hematologic disease and to the immunosuppression related to the therapy.
The majority of infections in CLL patients treated with alkilating agents is of bacterial origin. The immunodeficiency and natural infectious history of alkylator-resistant, corticosteroid-treated patients appears to have changed with the administration of purine analogs, which has been complicated by very severe and unusual infections and also more viral infections due to sustained reduction of CD4-positive T lymphocytes.
The subsequent introduction of monoclonal antibodies in therapies, in particular alemtuzumab, further increased the immunodepression, increasing also infections which appeared more often in patients with recurrent neutropenia due to chemotherapy cycles.
Epidemiological data regarding fungal infections in lymphoproliferative disorders are scarce.
Italian SEIFEM group in a retrospective multicentre study regarding CLL patients reported an incidence of mycoses 0.5%; however, chronic lymphoproliferative disorders emerged as second haematological underlying disease after acute leukemia in a French study on aspergillosis; in particular CLL with aspergillosis accounted for a third of these chronic lymphoproliferative diseases presenting mould infection.
J Travel Med. 2014 May-Jun;21(3):207-13.
doi: 10.1111/jtm.12115. Epub 2014 Mar 14.
1Environmental and Occupational Health Sciences, School of Public Health; Department of Anesthesiology, School of Medicine, Louisiana State University Health Sciences Center (LSUHSC), New Orleans, LA, USA.
Bacterial skin and soft tissue infections (SSTIs) in travelers often follow insect bites and can present a broad spectrum of clinical manifestations ranging from impetigo to necrotizing cellulitis. Significant SSTIs can also follow marine injuries and exposures in travelers, and the etiologies are often marine bacteria.
To meet the objectives of describing the pathogen-specific presenting clinical manifestations, diagnostic and treatment strategies, and outcomes of superficial and deep invasive infections in travelers caused by commonly encountered and newly emerging marine bacterial pathogens, Internet search engines were queried with the key words as MESH terms.
Travel medicine practitioners should maintain a high index of suspicion regarding potentially catastrophic, invasive bacterial infections, especially Aeromonas hydrophila, Vibrio vulnificus, Chromobacterium violaceum, and Shewanella infections, following marine injuries and exposures.
Travelers with well-known risk factors for the increasing severity of marine infections, including those with open wounds, suppressed immune systems, liver disease, alcoholism, hemochromatosis, hematological disease, diabetes, chronic renal disease, acquired immunodeficiency syndrome, and cancer, should be cautioned about the risks of marine infections through exposures to marine animals, seawater, the preparation of live or freshly killed seafood, and the accidental ingestion of seawater or consumption of raw or undercooked seafood, especially shellfish. With the exception of minor marine wounds demonstrating localized cellulitis or spreading erysipeloid-type reactions, most other marine infections and all Gram-negative and mycobacterial marine infections will require therapy with antibiotic combinations.
Aeromonas hydrophila ecthyma gangrenosum without bacteraemia in a diabetic man: the first case report in Italy.
Infez Med. 2009 Sep;17(3):184-7.
Avolio M1, La Spisa C, Moscariello F, De Rosa R, Camporese A.
1Microbiologia e Virologia, Dipartimento di Medicina di Laboratorio, Azienda Ospedaliera S. Maria degli Angeli, Pordenone, Italy.
Ecthyma gangrenosum is a well recognized cutaneous manifestation of severe, invasive infection by Pseudomonas aeruginosa usually in immunocompromised and critically ill patients. This type of infection is usually fatal. Aeromonas infection is infrequently reported as the cause of ecthyma gangrenosum. Here we show the first case described in Italy of Aeromonas hydrophila ecthyma gangrenosum in the lower extremities in an immunocompetent diabetic without bacteraemia. A 63-year-old obese diabetic male was admitted with an ulcer on his left leg, oedema, pain and fever. Throughout his hospitalization blood cultures remained sterile, but a culture of A. hydrophila was isolated following punctures from typical leg pseudomonal-ecthyma gangrenosum lesions developed after admission. The patient, questioned again, stated that a few days before he had worked in a well near his house without taking precautions. We conclude that early diagnosis and suitable antibiotic therapy are important for the management of ecthyma gangrenosum. The typical presentation of soft tissue infection of A. hydrophila should mimic a Gram-positive infection, which may result in a delay in administration of appropriate antibiotics. Moreover, A. hydrophila should be considered a possible agent for non-pseudomonal ecthyma gangrenosum in a diabetic man with negative blood cultures, in presence of anamnestical risk factors
JOURNAL OF CLINICAL MICROBIOLOGY Feb. 2001, p. 740–742
GRACIELA DAVEL,1 * PATRICIA FEATHERSTON,2 ANIBAL FERNA´NDEZ,2 RUBEN ABRANTES,1 CRISTINA CANTEROS,1 LAURA RODERO,1 CARLOS SZTERN,3 AND DIEGO PERROTTA1
Departamento Micologıa, INEI, ANLIS Dr. Carlos G. Malbran, Buenos Aires,1 and Hospital San Juan de Dios2 and Fundacion Jose Marıa Mainetti, Centro Oncologico,3 La Plata, Argentina
We report the first case of maxillary sinusitis caused by Actinomucor elegans in an 11-year-old patient. Histopathological and mycological examinations of surgical maxillary sinuses samples showed coenocytic hyphae characteristic of mucoraceous fungi. The fungi recovered had stolons and rhizoids, nonapophyseal and globose sporangia, and whorled branched sporangiophores and was identified as A. elegans. After surgical cleaning and chemotherapy with amphotericin B administered intravenously and by irrigation, the patient became asymptomatic and the mycological study results were negative.