Emergence of novel methicillin resistant Staphylococcus aureus strains in a tertiary care facility in Tiyadh, Saudi Arabia

Purpose: There is a need for continuous surveillance of methicillin-resistant Staphylococcus aureus (MRSA) to identify emergence of new strains. We hypothesize that MRSA strains are evolving with ongoing acquisition of SCCmec elements. This study was carried out to evaluate the evolution of MRSA at a tertiary care facility in Saudi Arabia. Methods: MRSA isolates associated with invasive clinical infection, which were identified in 2017 at the microbiology laboratory, King Khalid University Hospital (KKUH) in Riyadh, Saudi Arabia, were studied. The molecular characterization of isolates was carried out using StaphyType DNA microarray (Alere Technologies GmbH/Abbott, Jena, Germany). Results: The 125 MRSA isolates studied belonged to 18 clonal complexes (CC) which were distributed into 32 strain assignments. The predominant CC were CC5 (n=30), CC6 (n=17), CC80 (n=13), CC22 (n=12), CC361 (n=12). The findings demonstrated the first identification of CC152, CC361 and CC1153 MRSA as well as ST5-MRSA-[I+fus], “Geraldine Clone”, CC6-MRSA-IV (PVL+) and CC88-MRSA-V (PVL+), WA MRSA-117 in Saudi Arabia. Four novel variants were identified: CC5-MRSA-[VI+fus+tirS], CC22-MRSA-[V/VT+fus](PVL+), CC152-MRSA-[V+fus](PVL+) and CC361-MRSA-[VT+fus]. Fifty-four isolates (n/N=54/125; 43.2%) including the novel strains carried the Q6GD50 SCCfusC gene while the Panton-Valentine leukocidin genes were present in 30.4% (n/N=38/125). Conclusion: The findings demonstrate an expanding MRSA repertoire in our setting including emergence of previously unreported clonal complexes and novel strains. The high carriage of fusC gene suggests a role for fusidic acid misuse in driving the evolution of the MRSA genome and underscores the need for increased monitoring of antibiotic use.Purpose: There is a need for continuous surveillance of methicillin-resistant Staphylococcus aureus (MRSA) to identify emergence of new strains. We hypothesize that MRSA strains are evolving with ongoing acquisition of SCCmec elements. This study was carried out to evaluate the evolution of MRSA at a tertiary care facility in Saudi Arabia. Methods: MRSA isolates associated with invasive clinical infection, which were identified in 2017 at the microbiology laboratory, King Khalid University Hospital (KKUH) in Riyadh, Saudi Arabia, were studied. The molecular characterization of isolates was carried out using StaphyType DNA microarray (Alere Technologies GmbH/Abbott, Jena, Germany). Results: The 125 MRSA isolates studied belonged to 18 clonal complexes (CC) which were distributed into 32 strain assignments. The predominant CC were CC5 (n=30), CC6 (n=17), CC80 (n=13), CC22 (n=12), CC361 (n=12). The findings demonstrated the first identification of CC152, CC361 and CC1153 MRSA as well as ST5-MRSA-[I+fus], “Geraldine Clone”, CC6-MRSA-IV (PVL+) and CC88-MRSA-V (PVL+), WA MRSA-117 in Saudi Arabia. Four novel variants were identified: CC5-MRSA-[VI+fus+tirS], CC22-MRSA-[V/VT+fus](PVL+), CC152-MRSA-[V+fus](PVL+) and CC361-MRSA-[VT+fus]. Fifty-four isolates (n/N=54/125; 43.2%) including the novel strains carried the Q6GD50 SCCfusC gene while the Panton-Valentine leukocidin genes were present in 30.4% (n/N=38/125). Conclusion: The findings demonstrate an expanding MRSA repertoire in our setting including emergence of previously unreported clonal complexes and novel strains. The high carriage of fusC gene suggests a role for fusidic acid misuse in driving the evolution of the MRSA genome and underscores the need for increased monitoring of antibiotic use

Molecular investigations on a chimeric strain of Staphylococcus aureus sequence type 80

A PVL-positive, methicillin-susceptible Staphylococcus aureus was cultured from pus from cervical lymphadenitis of a patient of East-African origin. Microarray hybridisation assigned the isolate to clonal complex (CC) 80 but revealed unusual features, including the presence of the ORF-CM14 enterotoxin homologue and of an ACME-III element as well as the absence of etD and edinB. The isolate was subjected to both, Illumina and Nanopore sequencing allowing characterisation of deviating regions within the strain´s genome. Atypical features of this strain were attributable to the presence of two genomic regions that originated from other S. aureus lineages and that comprised, respectively, 3% and 1.4% of the genome. One deviating region extended from walJ to sirB. It comprised ORF-CM14 and the ACME-III element. A homologous but larger fragment was also found in an atypical S. aureus CC1/ST567 strain whose lineage might have served as donor of this genomic region. This region itself is a chimera comprising fragments from CC1 as well as fragments of unknown origin. The other deviating region comprised the region from htsB to ecfA2, i.e., another 3% of the genome. It was very similar to CC1 sequences. Either this suggests an incorporation of CC1 DNA into the study strain, or alternatively a recombination event affecting “canonical” CC80. Thus, the study strain bears witness of several recombination events affecting supposedly core genomic genes. Although the exact mechanism is not yet clear, such chimerism seems to be an additional pathway in the evolution of S. aureus. This could facilitate also a transmission of virulence and resistance factors and therefore offer an additional evolutionary advantage

Rapid Identification of Carbapenemase Genes in Gram-Negative Bacteria with an Oligonucleotide Microarray-Based Assay

<div><p>Rapid molecular identification of carbapenemase genes in Gram-negative bacteria is crucial for infection control and prevention, surveillance and for epidemiological purposes. Furthermore, it may have a significant impact upon determining the appropriate initial treatment and greatly benefit for critically ill patients. A novel oligonucleotide microarray-based assay was developed to simultaneously detect genes encoding clinically important carbapenemases as well as selected extended (ESBL) and narrow spectrum (NSBL) beta-lactamases directly from clonal culture material within few hours. Additionally, a panel of species specific markers was included to identify <i>Escherichia coli</i>, <i>Pseudomonas aeruginosa</i>, <i>Citrobacter freundii/braakii</i>, <i>Klebsiella pneumoniae</i> and <i>Acinetobacter baumannii</i>. The assay was tested using a panel of 117 isolates collected from urinary, blood and stool samples. For these isolates, phenotypic identifications and susceptibility tests were available. An independent detection of carbapenemase, ESBL and NSBL genes was carried out by various external reference laboratories using PCR methods. In direct comparison, the microarray correctly identified 98.2% of the covered carbapenemase genes. This included <i>bla</i>VIM (13 out of 13), <i>bla</i>GIM (2/2), <i>bla</i>KPC (27/27), <i>bla</i>NDM (5/5), <i>bla</i>IMP-2/4/7/8/13/14/15/16/31 (10/10), <i>bla</i>OXA-23 (12/13), <i>bla</i>OXA-40-group (7/7), <i>bla</i>OXA-48-group (32/33), <i>bla</i>OXA-51 (1/1) and <i>bla</i>OXA-58 (1/1). Furthermore, the test correctly identified additional beta-lactamases [<i>bla</i>OXA-1 (16/16), <i>bla</i>OXA-2 (4/4), <i>bla</i>OXA-9 (33/33), OXA-10 (3/3), <i>bla</i>OXA-51 (25/25), <i>bla</i>OXA-58 (2/2), CTX-M1/M15 (17/17) and <i>bla</i>VIM (1/1)]. In direct comparison to phenotypical identification obtained by VITEK or MALDI-TOF systems, 114 of 117 (97.4%) isolates, including <i>Acinetobacter baumannii</i> (28/28), <i>Enterobacter spec</i>. (5/5), <i>Escherichia coli</i> (4/4), <i>Klebsiella pneumoniae</i> (62/63), <i>Klebsiella oxytoca</i> (0/2), <i>Pseudomonas aeruginosa</i> (12/12), <i>Citrobacter freundii</i> (1/1) and <i>Citrobacter braakii</i> (2/2), were correctly identified by a panel of species specific probes. This assay might be easily extended, adapted and transferred to point of care platforms enabling fast surveillance, rapid detection and appropriate early treatment of infections caused by multiresistant Gram-negative bacteria.</p></div

Species genotyping results of the <b>M</b>icroarray-based assay in comparison to the <b>R</b>eference method (phenotypic results were obtained from University Medical Center of Dresden, University Medical Center of Jena, German Collection of Microorganisms and Cell Cultures, Institut Pasteur and Friedrich-Loeffler-Institute).

<p>Species genotyping results of the <b><u>M</u></b>icroarray-based assay in comparison to the <b><u>R</u></b>eference method (phenotypic results were obtained from University Medical Center of Dresden, University Medical Center of Jena, German Collection of Microorganisms and Cell Cultures, Institut Pasteur and Friedrich-Loeffler-Institute).</p

Additional lactamases detected by the microarray in comparison to conducted control PCRs.

<p>Additional lactamases detected by the microarray in comparison to conducted control PCRs.</p

Target overview of the microarray-based carbapenemases assay.

<p>Target overview of the microarray-based carbapenemases assay.</p

Carbapenemases genotyping results of the <b>M</b>icroarray-based assay in comparison to the genotyping results of carbapenemases genes obtained from different reference laboratories that used standard PCR as <b>R</b>eference method.

<p>Carbapenemases genotyping results of the <b><u>M</u></b>icroarray-based assay in comparison to the genotyping results of carbapenemases genes obtained from different reference laboratories that used standard PCR as <b><u>R</u></b>eference method.</p

Linear multiplex DNA amplification, labeling and hybridization with the ArrayStrips.

<p>(<b>a</b>) Linear Multiplex Amplification starting from clonal RNA-free genomic DNA. Extracted DNA is internally labeled with biotin (Label [L]) and amplified in a linear multiplex PCR reaction; (<b>b</b>) Hybridization: the internally biotin labeled, single-stranded DNA product hybridizes specifically under stringent conditions to the corresponding probes. The resulting duplex is detected using a horse-radish peroxidase (Enzyme [E]) – streptavidin conjugate, which causes the dye to precipitate ([S]). (<b>c</b>) Detection: the ArrayMate Reader (or ArrayTube Reader ATR 03) enables the visualization and subsequently automated analysis of the array image. The presence of a dark precipitated spot indicates successful hybridization; (<b>d</b>) Analysis: the assay specific software analysis script coming with the ArrayMate Reader (or ArrayTube Reader ATR 03), measures the signal intensity of each probe and determines which genes/alleles are present in the sample by means of an assay specific algorithm. (<b>e</b>) Genotype analysis: a software plugin coming with the ArrayMate Reader (or ArrayTube Reader ATR 03) analyzed the raw data automatically, finally a report is provided on the detected carbapenemases genes.</p

Characterisation of a novel composite SCCmec-SCCfus element in an emerging Staphylococcus aureus strain from the Arabian Gulf region

Fusidic acid is a steroid antibiotic known since the 1960s. It is frequently used in topical preparations, i.e., ointments, for the treatment of skin and soft tissue infections caused by Staphylococcus aureus. There is an increasing number of methicillin-resistant S. aureus (MRSA) strains that harbour plasmid-borne fusB/far1 or fusC that is localised on SCC elements. In this study we examined a series of related CC30-MRSA isolates from the Arabian Gulf countries that presented with SCCmec elements and fusC, including a variant that—to the best of our knowledge—has not yet formally been described. It consisted of a class B mec complex and ccrA/B-4 genes. The fusidic acid resistance gene fusC was present, but contrary to the previously sequenced element of HDE288, it was not accompanied by tirS. This element was identified in CC30 MRSA from Kuwait, Saudi Arabia and the United Arab Emirates that usually also harbour the Panton-Valentin leukocidin (PVL) genes. It was also identified in CC8 and ST834 isolates. In addition, further CC30 MRSA strains with other SCCmec VI elements harbouring fusC were found to circulate in the Arabian Gulf region. It can be assumed that MRSA strains with SCCmec elements that include fusC have a selective advantage in both hospital and community settings warranting a review of the use of topical antibiotics and indicating the necessity of reducing over-the-counter sale of antibiotics, including fusidic acid, without prescription.Fusidic acid is a steroid antibiotic known since the 1960s. It is frequently used in topical preparations, i.e., ointments, for the treatment of skin and soft tissue infections caused by Staphylococcus aureus. There is an increasing number of methicillin-resistant S. aureus (MRSA) strains that harbour plasmid-borne fusB/far1 or fusC that is localised on SCC elements. In this study we examined a series of related CC30-MRSA isolates from the Arabian Gulf countries that presented with SCCmec elements and fusC, including a variant that—to the best of our knowledge—has not yet formally been described. It consisted of a class B mec complex and ccrA/B-4 genes. The fusidic acid resistance gene fusC was present, but contrary to the previously sequenced element of HDE288, it was not accompanied by tirS. This element was identified in CC30 MRSA from Kuwait, Saudi Arabia and the United Arab Emirates that usually also harbour the Panton-Valentin leukocidin (PVL) genes. It was also identified in CC8 and ST834 isolates. In addition, further CC30 MRSA strains with other SCCmec VI elements harbouring fusC were found to circulate in the Arabian Gulf region. It can be assumed that MRSA strains with SCCmec elements that include fusC have a selective advantage in both hospital and community settings warranting a review of the use of topical antibiotics and indicating the necessity of reducing over-the-counter sale of antibiotics, including fusidic acid, without prescription