Implanted Port Catheter System Infection Caused by Methicillin-resistant Staphylococcus pseudintermedius ST71-SCCmec type III

Staphylococcus pseudintermedius is commonly associated with skin and soft tissue infections in dogs. However, infections caused by S. pseudintermedius are only rarely reported in humans, and this pathogen is frequently misidentified as S. aureus. We herein report a case of an implanted port catheter system infection caused by methicillin-resistant S. pseudintermedius (MRSP) in a patient with hepatocellular carcinoma. The patient was also a dog owner. S. pseudintermedius was first identified using the Vitek2 system (BioMérieux). Whole-genome sequencing revealed that this MRSP was a sequence type 71-carrying staphylococcal cassette chromosome mec type III (ST71-SCCmec III) isolate.

Staphylococcus ursi sp. nov., a new member of the 'Staphylococcus intermedius group' isolated from healthy black bears

Six Staphylococcus strains were isolated from healthy black bears (Ursus americanus) in the Great Smoky Mountains National Park, Tennessee, USA. Phylogenetic analysis based on complete genome, 16S rRNA, dnaJ, hsp60, rpoB and sodA genes, and MALDI-TOF-MS main spectral profiles revealed that the strains belonged to one species and showed the closest relatedness to members of the 'Staphylococcus intermedius group' (SIG), which include Staphylococcus intermedius, Staphylococcus pseudintermedius, Staphylococcus delphini and Staphyloccoccus cornubiensis. The strains were positive in SIG-specific and negative in individual species-specific PCR assays for the nuc gene. The strains can be differentiated from the other SIG species by the absence of sucrose fermentation, from S. intermedius DSM 20373^T, S. pseudintermedius CCUG 49543^T and S. cornubiensis DSM 105366^T by the absence of methyl β-d-glucopyranoside fermentation and from S. delphini DSM 20771^T by fermentation of trehalose. DNA relatedness of the type strain MI 10-1553^T with the type strains of S. delphini, S. pseudintermedius, S. intermedius and S. cornubiensis was ≤48.2 % by digital DNA-DNA hybridization and ≤92.3 % by average nucleotide identity calculations. Iso-_C15:0, anteiso-C_15 : 0 and anteiso-C_17 : 0 were the most common fatty acids. Polar lipids consisted of phosphadidylglycerols, phospholipids, glycolipid, diphosphatidylglycerol and aminophospholipid. Cell-wall peptidoglycan was of type A3α l-Lys-Gly₃ (Ser; similar to A11.2 and A11.3). The respiratory quinone belonged to menaquinone 7 (MK-7). The G+C content of MI 10-1553^T was 39.3 mol%. The isolated strains represent a novel species of the genus Staphylococcus, for which we propose the name Staphylococcus ursi sp. nov. The type strain is MI 10-1553^T (=ATCC TSD-55^T=CCOS 1900^T).

Performance of Five Commercial Identification Platforms for Identification of Staphylococcus delphini

The Staphylococcus intermedius group (SIG) is a collection of coagulase-positive staphylococci consisting of four distinct species, namely, Staphylococcus cornubiensis, Staphylococcus delphini, Staphylococcus intermedius, and Staphylococcus pseudintermedius SIG members are animal pathogens and rare causes of human infection. Accurate identification of S. pseudintermedius has important implications for interpretation of antimicrobial susceptibility testing data and may be important for other members of the group. Therefore, we sought to evaluate the performance of five commercially available identification platforms with 21 S. delphini isolates obtained from a variety of animal and geographic sources. Here, we show that automated biochemical platforms were unable to identify S. delphini to the species level, a function of its omission from their databases, but could identify isolates to the SIG level with various degrees of success. However, all automated systems misidentified at least one isolate as Staphylococcus aureus One matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) system was able to identify S. delphini to the species level, suggesting that MALDI-TOF MS is the best option for distinguishing members of the SIG. With the exception of S. pseudintermedius, it is unclear if other SIG members should be routinely identified to the species level; however, as our understanding of their role in animal and human diseases increases, it may be necessary and important to do so.

Reduced rates of antimicrobial resistance in Staphylococcus intermedius group and Escherichia coli isolated from diseased companion animals in an animal hospital after restriction of antimicrobial use

The 2016 National Action Plan aims for reduction in antimicrobial resistance (AMR) to tetracyclines, third-generation cephalosporins, and fluoroquinolones in Escherichia coli isolates from livestock: to lower the tetracycline resistance of E. coli to 33% or less; to maintain the third-generation cephalosporin resistance of E. coli at the same level as in the other G7 countries as of 2020; and to maintain the fluoroquinolone resistance of E. coli at the same level as in the other G7 countries as of 2020. A relatively unexplored facet of reducing AMR is the impact of minimizing transmission of AMR strains by companion animals. In this study we compared AMR rates in Staphylococcus intermedius group (SIG) and E. coli isolated from diseased companion animals in an animal hospital before and after restriction of antimicrobial use. Our study spanned a 4.5-year period from 2014 to June 2018 during which antimicrobial use was restricted in 2016. During this period, abundance of methicillin-resistant SIG isolates from the hospital dropped from 41.5% to 9.3%, and that of extended-spectrum β-lactamase (ESBL)-producing E. coli isolates dropped from 29.5% to 9.5%. Tests for antimicrobial susceptibility revealed significantly reduced rates of AMR to enrofloxacin and levofloxacin in SIG isolates, and to cefazolin in E. coli isolates after antimicrobial use was restricted. Our observations suggest that restriction of antimicrobial use, especially that of third-generation cephalosporins and fluoroquinolones, is an effective method for reducing AMR rates. These findings will be relevant in guiding antimicrobial restriction approaches in other animal hospitals and clinics.

[The modern characteristics of species identification of coagulase-positive bacteria of Staphylococcus genus.]

The development of molecular techniques of research in the end of XX century permitted to broaden nomenclature of species forming genus Staphylococcus that nowadays numbers 51 species and 27 sub-species. The pathogenic species of genus have a capacity to coagulate blood plasma of mammals forming group of coagulase-positive staphylococci including 7 species: S. aureus, S. delphini, S. intermedius, S. pseudintermedius, S. lutrae, S. schleiferi ssp. сoagulans, S hyicus. In clinical practice, S.aureus is considered as the most virulent among staphylococci. The cumulated data testifies increasing etiologic significance of other representatives of group of coagulase-positive staphylococci in human and animal infection pathology. The keen attention is needed to be paid to Staphylococcus intermedius of group (SIG), uniting three close kindred species: S. pseudintermedius, S. intermedius, S. delphini. Among them the most broadly prevailed are methicillin-resistant clones of S. pseudintermedius, capable to bring on in patient various pyoinflammatory diseases. The laboratory methods based on phenotype tests, provide no opportunity to differentiate coagulase-positive staphylococci because of significant similarity of phenotype characteristics in certain representatives of this group. Te comparative analysis was implemented concerning efficiency of various methods of species identification of coagulase-positive staphylococci: biochemical, molecular genetic (multi-primer polymerase chain reaction for identifying differences in gene structure of thermonuclease, analysis of polymorphism of lengths of restricting fragments of catalase gene and their sequencing), matrix-activated laser desorptional/ionizing time-of-flight mass-spectrometry (MALDI-ToF MS) with various modes of probe preparation. The analysis was applied to 117 isolates of representatives of SIG, separated from ill and healthy individuals of small domestic animals, clinical isolates form patients of hospitals. The multi-primer polymerase chain reaction permitted to identify 97% of isolates, analysis of polymorphism of lengths of restricting fragments of catalase gene - 100% of isolates that confirms efficiency of molecular genetic methods of analysis. The MALDI-ToF MS requires replenishment data base of mass-spectrometer and application of the mode of preliminary protein extraction of samples fo increasing efficiency of species identification of coagulase-positive staphylococci.

First reported human isolation of Staphylococcus delphini

The Staphylococcus intermedius group is a collection of coagulase-positive staphylococci composed of 5 members, including Staphylococcus pseudintermedius, a zoonotic pathogen often associated with exposure to dogs, and Staphylococcus delphini, which has not previously been recovered from humans. Here, we describe the first human case of S. delphini infection.

Epidemiology, Clinical Characteristics, and Antimicrobial Susceptibility Profiles of Human Clinical Isolates of Staphylococcus intermedius Group. J Clin Microbiol. 2018;56. [PMID: 29305548 DOI: 10.1128/jcm.01788-17]

The veterinary pathogens in the Staphylococcus intermedius group (SIG) are increasingly recognized as causes of human infection. Shared features between SIG and Staphylococcus aureus may result in the misidentification of SIG in human clinical cultures. This study examined the clinical and microbiological characteristics of isolates recovered at a tertiary-care academic medical center. From 2013 to 2015, 81 SIG isolates were recovered from 62 patients. Patients were commonly ≥50 years old, diabetic, and/or immunocompromised. Documentation of dog exposure in the electronic medical record was not common. Of the 81 SIG isolates, common sites of isolation included 37 (46%) isolates from wound cultures and 17 (21%) isolates from respiratory specimens. Although less common, 10 (12%) bloodstream infections were documented in 7 unique patients. The majority of SIG (65%) isolates were obtained from polymicrobial cultures. In comparison to S. aureus isolates from the same time period, significant differences were noted in proportion of SIG isolates that were susceptible to doxycycline (74% versus 97%, respectively; P < 0.001), trimethoprim-sulfamethoxazole (65% versus 97%, respectively; P < 0.001), and ciprofloxacin (78% versus 59%, respectively; P < 0.01). Methicillin resistance (MR) was detected in 12 (15%) of 81 SIG isolates. All MR isolates detected by an oxacillin disk diffusion test would have been misclassified as methicillin susceptible using a cefoxitin disk diffusion test. Thus, SIG is recovered from human clinical specimens, and distinction of SIG from S. aureus is critical for the accurate characterization of MR status in these isolates.

Evaluation of Pyrrolidonyl Arylamidase Activity in Staphylococcus delphini

Clinical reference textbooks lack data for pyrrolidonyl arylamidase (PYR) activity in Staphylococcus delphini This study evaluated PYR activities of 21 S. delphini strains by reference broth, rapid disc, and rapid slide methods. Species and subgroup identifications were confirmed by nucleic acid-based methods and included nine group A and 12 group B strains. Testing by rapid PYR methods with products from four manufacturers was performed at two testing locations, and, with the exception of one strain tested at one location using reagents from one manufacturer, each S. delphini strain tested positive for PYR activity. Therefore, PYR may be a useful single-test adjunct for distinguishing Staphylococcus aureus from S. delphini and other members of the Staphylococcus intermedius group.

An evaluation of matrix-assisted laser desorption ionization time-of-flight mass spectrometry for the identification of Staphylococcus pseudintermedius isolates from canine infections

It has been proposed, based on taxonomic and molecular studies, that all canine isolates belonging to Staphylococcus intermedius group (SIG) should be renamed Staphylococcus pseudintermedius. However, isolates of SIG and other coagulase-positive staphylococci share many phenotypic characteristics, which could lead to misidentification. The accuracy of matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) for identifying S. pseudintermedius isolates obtained from canine infections was evaluated, using a polymerase chain reaction (PCR)-based identification as the gold standard. In addition, MALDI-TOF MS was compared with conventional biochemical tests. A central problem was the incorrect identification of S. pseudintermedius isolates as S. intermedius by either MALDI-TOF MS or biochemical identification. From the 49 S. pseudintermedius isolates identified by the molecular method, only 21 could be assigned to this species by the biochemical approach and only 12 by MALDI-TOF MS. The 6 S. aureus isolates were correctly identified by all 3 techniques. However, using biochemical tests, 9 S. pseudintermedius were mistakenly classified as S. aureus, indicating a reduced specificity relative to the MALDI-TOF MS system. Analysis with the MALDI-TOF MS platform allowed rapid and accurate identification of the 49 isolates to the S. intermedius group but the approach was very limited in identifying S. pseudintermedius isolates, as only 12 of 49 isolates were correctly identified, a sensitivity of 0.24 (95% confidence interval: 0.13-0.39).