Staphylococcus aureus in patients with Buruli ulcer and burns in Ghana

Huidwonden zijn bijzonder vatbaar voor secundaire bacteriële infecties. Dit is met name een probleem in zorginstellingen met beperkte financiële middelen en een ontoereikende infectiepreventie. Het onderhavige promotieonderzoek had tot doel om de implicaties van bacteriële wondkolonisatie in een dergelijke setting te onderzoeken. Hiertoe werd specifiek de kolonisatie van zogenaamde Buruli ulcers (zweren) en brandwonden door de bacterie Staphylococcus aureus in Ghanese zorginstellingen bestudeerd. Buruli ulcer is een ernstige ziekte van huid en onderhuids weefsel die tot de Verwaarloosde Tropenziekten wordt gerekend en die wordt veroorzaakt door Mycobacterium ulcerans, een bacterie die verwant is aan de veroorzakers van tuberculose en lepra. Brandwonden behoren tot de ernstigste vormen van huidletsel en ~90% of van alle brandwonden komt voor in lagelonenlanden zoals Ghana. Buruli ulcers en brandwonden kunnen gekoloniseerd worden door vele soorten micro-organismen, waaronder de S. aureus bacterie die wondgenezing kan belemmeren. Met geavanceerde technieken, met name de sequentieanalyse van complete bacteriële genomen, werd de aanwezigheid en diversiteit van S. aureus in Buruli ulcers en brandwonden geanalyseerd. Hiermee kon ook de overdracht van S. aureus tussen patiënten en ziekenhuispersoneel aangetoond worden. De vergelijking van genoomsequenties leidde zelfs tot het opsporen van onopgemerkte uitbraken van uiterst antibioticum-resistente S. aureus varianten, waaronder de beruchte MRSA-bacterie. Daarnaast werden de genoomsequenties gebruikt om een inschatting te maken van de aanvalskracht van de verzamelde S. aureus stammen. De resultaten tonen de noodzaak van adequate wondzorg, ziekenhuishygiëne en infectiepreventie aan. Juist in lagelonenlanden, zoals Ghana, is dit van eminent belang om ernstige infecties door antibioticum-resistente bacteriën te voorkomen

Methicillin Resistant Staphylococcus aureus Transmission in a Ghanaian Burn Unit:The Importance of Active Surveillance in Resource-Limited Settings

Objectives:Staphylococcus aureus infections in burn patients can lead to serious complications and death. The frequency of S. aureus infection is high in low- and middle-income countries presumably due to limited resources, misuse of antibiotics and poor infection control. The objective of the present study was to apply population genomics to precisely define, for the first time, the transmission of antibiotic resistant S. aureus in a resource-limited setting in sub-Saharan Africa.Methods:Staphylococcus aureus surveillance was performed amongst burn patients and healthcare workers during a 7-months survey within the burn unit of the Korle Bu Teaching Hospital in Ghana.Results: Sixty-six S. aureus isolates (59 colonizing and 7 clinical) were obtained from 31 patients and 10 healthcare workers. Twenty-one of these isolates were ST250-IV methicillin-resistant S. aureus (MRSA). Notably, 25 (81%) of the 31 patients carried or were infected with S. aureus within 24 h of admission. Genome comparisons revealed six distinct S. aureus clones circulating in the burn unit, and demonstrated multiple transmission events between patients and healthcare workers. Further, the collected S. aureus isolates exhibited a wide range of genotypic resistances to antibiotics, including trimethoprim (21%), aminoglycosides (33%), oxacillin (33%), chloramphenicol (50%), tetracycline (59%) and fluoroquinolones (100%).Conclusion: Population genomics uncovered multiple transmission events of S. aureus, especially MRSA, within the investigated burn unit. Our findings highlight lapses in infection control and prevention, and underscore the great importance of active surveillance to protect burn victims against multi-drug resistant pathogens in resource-limited settings

Virulence potential of Staphylococcus aureus isolates from Buruli ulcer patients

Buruli ulcer (BU) is a necrotizing infection of the skin and subcutaneous tissue caused by Mycobacterium ulcerans. BU wounds may also be colonized with other microorganisms including Staphylococcus aureus. This study aimed to characterize the virulence factors of S. aureus isolated from BU patients. Previously sequenced genomes of 21 S. aureus isolates from BU patients were screened for the presence of virulence genes. The results show that all S. aureus isolates harbored on their core genomes genes for known virulence factors like alpha-hemolysin, and the a and beta-phenol soluble modulins. Besides the core genome virulence genes, mobile genetic elements (MGEs), i.e. prophages, genomic islands, pathogenicity islands and a Staphylococcal cassette chromosome (ECG) were found to carry different combinations of virulence factors, among them genes that are known to encode factors that promote immune evasion, superantigens and Panton-Valentine Leucocidin. The present observations imply That the S. aureus isolates from BU patients harbor a diverse repertoire of virulence genes that may enhance bacterial survival and persistence in the wound environment and potentially contribute to delayed wound healing

Molecular Characterization of Staphylococcus aureus Isolates Transmitted between Patients with Buruli Ulcer

BACKGROUND:Buruli ulcer (BU) is a skin infection caused by Mycobacterium ulcerans. The wounds of most BU patients are colonized with different microorganisms, including Staphylococcus aureus. METHODOLOGY:This study investigated possible patient-to-patient transmission events of S. aureus during wound care in a health care center. S. aureus isolates from different BU patients with overlapping visits to the clinic were whole-genome sequenced and analyzed by a gene-by-gene approach using SeqSphere(+) software. In addition, sequence data were screened for the presence of genes that conferred antibiotic resistance. PRINCIPAL FINDINGS:SeqSphere(+) analysis of whole-genome sequence data confirmed transmission of methicillin resistant S. aureus (MRSA) and methicillin susceptible S. aureus among patients that took place during wound care. Interestingly, our sequence data show that the investigated MRSA isolates carry a novel allele of the fexB gene conferring chloramphenicol resistance, which had thus far not been observed in S. aureus

<i>spa</i>-types of 91 <i>S. aureus</i> isolates from the anterior nares and wounds of 19 BU patients.

<p><i>spa</i>-types of 91 <i>S. aureus</i> isolates from the anterior nares and wounds of 19 BU patients.</p

Genetic Diversity of <i>Staphylococcus aureus</i> in Buruli Ulcer

<div><p>Background</p><p>Buruli ulcer (BU) is a necrotizing skin disease caused by Mycobacterium ulcerans. Previous studies have shown that wounds of BU patients are colonized with M. ulcerans and several other microorganisms, including <i>Staphylococcus aureus</i>, which may interfere with wound healing. The present study was therefore aimed at investigating the diversity and topography of <i>S. aureus</i> colonizing BU patients during treatment.</p><p>Methodology</p><p>We investigated the presence, diversity, and spatio-temporal distribution of <i>S. aureus</i> in 30 confirmed BU patients from Ghana during treatment. <i>S. aureus</i> was isolated from nose and wound swabs, and by replica plating of wound dressings collected bi-weekly from patients. <i>S. aureus</i> isolates were characterized by multiple-locus variable number tandem repeat fingerprinting (MLVF) and spa-typing, and antibiotic susceptibility was tested.</p><p>Principal Findings</p><p>Nineteen (63%) of the 30 BU patients tested positive for <i>S. aureus</i> at least once during the sampling period, yielding 407 <i>S. aureus</i> isolates. Detailed analysis of 91 isolates grouped these isolates into 13 MLVF clusters and 13 spa-types. Five (26%) <i>S. aureus</i>-positive BU patients carried the same <i>S. aureus</i> genotype in their anterior nares and wounds. <i>S. aureus</i> isolates from the wounds of seven (37%) patients were distributed over two different MLVF clusters. Wounds of three (16%) patients were colonized with isolates belonging to two different genotypes at the same time, and five (26%) patients were colonized with different <i>S. aureus</i> types over time. Five (17%) of the 30 included BU patients tested positive for methicillin-resistant <i>S. aureus</i> (MRSA).</p><p>Conclusion/Significance</p><p>The present study showed that the wounds of many BU patients were contaminated with <i>S. aureus</i>, and that many BU patients from the different communities carried the same <i>S. aureus</i> genotype during treatment. This calls for improved wound care and hygiene.</p></div

<i>S. aureus</i> wound topography in BU patients.

<p>Used dressings from wounds of BU patients were replica-plated onto CLED agar plates, and <i>S. aureus</i> colonies thus obtained were typed by MLVF. <i>S. aureus</i> colonies belonging to different MLVF clusters are shown in different colors: cluster A, red circles; cluster D, blue circles; cluster F, yellow circles; cluster H, green circle and cluster L, purple circles. (A) Replica plate of a wound dressing collected from patient 7 at time point t8 with <i>S. aureus</i> colonies belonging to clusters A and D, (B) Replica plate of a wound dressing collected from patient 7 at time t5 with <i>S. aureus</i> colonies belonging to clusters F and H. (C) Replica plate of a wound dressing collected from patient 22 at time t6 with <i>S. aureus</i> colonies belonging to clusters A and L.</p