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Deficiencies of the enzymes in lysosomes result in the accumulation of undegraded materials and subsequently cellular dysfunction. Early identification of deficiencies can lead to better clinical outcomes before irreversible organ and tissue damages occur. In this chapter, lysosomal enzymes are extracted from dried blood spots and incubated with the commercialized and multiplexed enzyme cocktail containing corresponding substrates and internal standards. After incubation, the enzymatic reactions are quenched, and the mixtures of the reaction products are prepared using liquid/liquid extractions. Multiple enzymes are quantified simultaneously using selected ion monitoring on liquid chromatography-mass spectrometry (LC-MS/MS) system.

Objective To evaluate the initial cutoff values, rates of screen positives, and genotypes for the large-scale newborn screening program for multiple mucopolysaccharidoses (MPS) in Taiwan. Study design More than 100 000 dried blood spots were collected consecutively as part of the national Taiwan newborn screening programs. Enzyme activities were measured by tandem mass spectrometry from dried blood spot punches. Genotypes were obtained when a second newborn screening specimen again had a decreased enzyme activity. Additional clinical evaluation was then initiated based on enzyme activity and/or genotype. Results Molecular genetic analysis for cases with low enzyme activity revealed 5 newborns with pathogenic alpha-L-iduronidase mutations, 3 newborns with pathogenic iduronate-2-sulfatase mutations, and 1 newborn was a carrier of an arylsulfatase B mutation. Several variants of unknown pathogenic significance were also identified, most likely causing pseudodeficiency. Conclusions The highly robust tandem mass spectrometry-based enzyme assays for MPS-I, MPS-II, and MPS-VI allow for high-throughput newborn screening for these lysosomal storage disorders. Optimized cutoff values combined with second tier testing could largely eliminate false-positive results. Accordingly, newborn screening for these lysosomal storage disorders is possible.

Background: Mucopolysaccharidosis II (MPS II) is an X-linked disorder resulting from a deficiency in lysosomal enzyme iduronate-2-sulfatase (IDS), which causes the accumulation of glycosaminoglycans (GAGs) in the lysosomes of many tissues and organs, leading to progressive cellular dysfunction. An MPS II newborn screening program has been available in Taiwan since 2015. The aim of the current study was to collect and analyze the long-term follow-up data of the screen-positive subjects in this program. Methods: From August 2015 to April 2022, 548,624 newborns were screened for MPS II by dried blood spots using tandem mass spectrometry, of which 202 suspected infants were referred to our hospital for confirmation. The diagnosis of MPS II was confirmed by IDS enzyme activity assay in leukocytes, quantitative determination of urinary GAGs by mass spectrometry, and identification of the IDS gene variant. Results: Among the 202 referred infants, 10 (5%) with seven IDS gene variants were diagnosed with confirmed MPS II (Group 1), 151 (75%) with nine IDS gene variants were classified as having suspected MPS II or pseudodeficiency (Group 2), and 41 (20%) with five IDS gene variants were classified as not having MPS II (Group 3). Long-term follow-up every 6 months was arranged for the infants in Group 1 and Group 2. Intravenous enzyme replacement therapy (ERT) was started in four patients at 1, 0.5, 0.4, and 0.5 years of age, respectively. Three patients also received hematopoietic stem cell transplantation (HSCT) at 1.5, 0.9, and 0.6 years of age, respectively. After ERT and/or HSCT, IDS enzyme activity and the quantity of urinary GAGs significantly improved in all of these patients compared with the baseline data. Conclusions: Because of the progressive nature of MPS II, early diagnosis via a newborn screening program and timely initiation of ERT and/or HSCT before the occurrence of irreversible organ damage may lead to better clinical outcomes. The findings of the current study could serve as baseline data for the analysis of the long-term effects of ERT and HSCT in these patients.

The fusidic acid (FUS) resistance determinants fusB, fusC, fusD and fusF in coagulase-negative staphylococci (CoNS) clinical isolates were examined. Among 208 FUS-resistant isolates, the fusB gene was the most common resistance determinant in each species, except in Staphylococcus hominis subsp. hominis or in species carrying intrinsic fusD or fusF. In S. hominis subsp. hominis, the fusC gene was the major determinant responsible for FUS resistance. To understand the genetic context of fusC in S. hominis subsp. hominis, 31 fusC-positive S. hominis subsp. hominis isolates were examined. Among these isolates, 14 carried SCCfusC, 3 carried an SCC476-like element and 7 carried a new SCC structure (SCC3390). As shown by pulsed-field gel electrophoresis (PFGE) and multilocus sequence typing (MLST) analyses, the S. hominis subsp. hominis clinical isolates showed limited clonality. Taken together, SCCfusC has been found in S. hominis subsp. hominis, Staphylococcus epidermidis, Staphylococcus haemolyticus, Staphylococcus capitis subsp. ureolyticus and Staphylococcus aureus, suggesting its wide distribution and spread among different species of staphylococci.

Mucopolysaccharidoses (MPSs) are a group of lysosomal storage diseases (LSDs) caused by an inherited gene defect. MPS patients can remain undetected unless the initial signs or symptoms have been identified. Newborn screening (NBS) programs for MPSs have been implemented in Taiwan since 2015, and more than 48.5% of confirmed cases of MPS have since been referred from these NBS programs. The purpose of this study was to report the current status of NBS for MPSs in Taiwan and update the gold standard criteria required to make a confirmative diagnosis of MPS, which requires the presence of the following three laboratory findings: (1) elevation of individual urinary glycosaminoglycan (GAG)-derived disaccharides detected by MS/MS-based assay, (2) deficient activity of a particular leukocyte enzyme by fluorometric assay, and (3) verification of heterogeneous or homogeneous variants by Sanger sequencing or next generation sequencing. Up to 30 April 2021, 599,962 newborn babies have been screened through the NBS programs for MPS type I, II, VI, and IVA, and a total of 255 infants have been referred to MacKay Memorial Hospital for a confirmatory diagnosis. Of these infants, four cases were confirmed to have MPS I, nine cases MPS II, and three cases MPS IVA, with prevalence rates of 0.67, 2.92, and 4.13 per 100,000 live births, respectively. Intensive long-term regular physical and laboratory examinations for asymptomatic infants with confirmed MPS or with highly suspected MPS can enhance the ability to administer ERT in a timely fashion.

Objectives Small colony variants (SCVs) of Staphylococcus aureus are associated with persistent and drug-resistant infections. We demonstrated for the first time the emergence of SCVs in a patient with vancomycin-intermediate S. aureus (VISA) infection during long-term treatment with daptomycin. Methods A 73-year-old man with septic arthritis was infected with VISA. The patient was treated with daptomycin; however, the patient remained infected with VISA, with continuous isolation of VISA from his blood during long-term treatment. Five VISA isolates were characterized by: PFGE; genotyping including staphylococcal cassette chromosome mec (SCCmec), spa and MLST; antimicrobial susceptibility testing; and scanning and transmission electron microscopy. WGS and fatty acid analysis were also performed. Results The five VISA isolates were from a single clone of ST239/spa3(t037) and, of these, the first three were SCCmecIII positive and daptomycin susceptible, whereas the last two were SCCmecIII negative and daptomycin resistant and exhibited the characteristics of SCVs. The first and last isolates showed 13 remarkable genetic differences in SCCmec and the mprF, cls2, clpX and fabF genes. Of these, mutation of fabF (encoding the fatty acid synthase) seemed to be partially responsible for the slow growth and ultrastructural features, including an abnormal intercellular substance, and for the daptomycin resistance of SCVs. Conclusions For the first time, we identified SCVs of VISA in a patient with septic arthritis during long-term treatment with daptomycin. Daptomycin-resistant SCVs of VISA were evolved in a stepwise manner and the mutation of fabF is likely responsible for the physical and ultrastructural characteristics and daptomycin resistance.

A high prevalence of fusC (16/46, 59%) was found in fusidic acid-resistant methicillin-resistant Staphylococcus aureus isolates collected from 2008 to 2010. Nucleotide sequencing of fusC and flanking regions revealed a novel staphylococcal cassette chromosome (SCC) structure, SCC fusC , which was integrated into rlmH and located upstream from SCC mec . The SCC fusC element contained speG , which may contribute to the polyamine resistance.

We analyzed the staphylococcal cassette chromosome mec (SCC mec ) types of 143 fusidic acid- and methicillin-resistant Staphylococcus epidermidis isolates. The most frequent SCC mec type was SCC mec III/SCC Hg (53%), followed by SCC mec IV (29%). Clonal spreading of SCC mec III/SCC Hg strains contributed to the increased prevalence of SCC mec III. A novel non- mec SCC structure, SCC 7684 , adjacent to SCC mec III, which carries a new ccrC allotype ( ccrC3 allele 1) and contains heavy metal resistance genes, was identified in 14 isolates.

Bor-Shiunn Lee,1 Chien-Chen Lee,2 Yi-Ping Wang,2 Hsiao-Jan Chen,3 Chern-Hsiung Lai,4 Wan-Ling Hsieh,1 Yi-Wen Chen2 1Graduate Institute of Oral Biology, 2Graduate Institute of Clinical Dentistry, School of Dentistry, National Taiwan University and National Taiwan University Hospital, 3Department of Clinical Laboratory Sciences and Medical Biotechnology, College of Medicine, National Taiwan University, Taipei, 4College of Life Science, Kaohsiung Medical University, Kaohsiung, Taiwan Abstract: Chronic periodontitis is characterized by inflammation of periodontal tissues, leading to bone resorption and tooth loss. The goal of treatment is to regenerate periodontal tissues including bone and cementum lost as a consequence of disease. The local delivery of tetracycline was proven to be effective in controlling localized periodontal infection without apparent side effects. Previous studies suggested that lovastatin has a significant role in new bone formation; however, the local delivery of lovastatin might enhance its therapeutic effects. A number of local delivery devices have been developed recently, including poly(D,L-lactide-co-glycolide acid) (PLGA) nanoparticles. The aim of this study was to develop a local delivery device, PLGA-lovastatin-chitosan-tetracycline nanoparticles, which allows the sequential release of tetracycline and lovastatin to effectively control local infection and promote bone regeneration in periodontitis. The size and microstructure of nanoparticles were examined by transmission electron microscopy, Nanoparticle Size Analyzer, and Fourier transform infrared spectroscopy. The release of tetracycline and lovastatin was quantified using a UV-Vis spectrophotometer. Furthermore, the cytotoxic effect and alkaline phosphatase activity of the nanoparticles in osteoblast cell cultures as well as antibacterial activity against periodontal pathogens were investigated. Finally, the bone regeneration potential of PLGA nanoparticles in three-walled defects in beagle dogs was investigated. The results indicated that PLGA-lovastatin-chitosan-tetracycline nanoparticles showed good biocompatibility, antibacterial activity, and increased alkaline phosphatase activity. The volumetric analysis from micro-CT revealed significantly increased new bone formation in defects filled with nanoparticles in dogs. This novel local delivery device might be useful as an adjunctive treatment in periodontal regenerative therapy. Keywords: lovastatin, tetracycline, chitosan, poly(d,l-lactide-co-glycolide acid), periodontal regeneration

Gemella morbillorum, a low G+C content Gram-positive bacterium, is considered to be a commensal organism in humans but occasionally causes endocarditis or other diseases. We determined the sequences of groESL, dnaK and their flanking regions in G. morbillorum. Sequence analysis revealed the presence of putative CtsR binding sites in both groE and dnaK operons, but the lack of CIRCE in groE and the presence of CIRCE in dnaK. This finding suggests in addition to the known regulatory systems for the class I heat shock protein genes, there may be another model in G. morbillorum. Furthermore, an unusual organization of the groE operon as groES-groEL-trxA was found. Genome sequence on GenBank database and southern blot indicate that there is only one copy of trxA in G. morbillorum. Sequencing of the groE locus from other Gemella species and clinical isolates revealed the same genetic structure, suggesting the conservation of the structure in Gemella species. Northern hybridization revealed that there were two transcripts, a large transcript, groES-groEL-trxA and a small transcript, trxA, in groE operon. Treatment of heat or diamide increased the transcription level of groES-groEL-trxA, whereas these two stresses did not affect the small trxA transcript. Thus, this study reveals that the trxA is co-transcribed with the groE operon, and most possibly under the control of the CtsR.

To understand the high prevalence of fusB genes in fusidic acid-resistant Staphylococcus epidermidis , analysis of resistance elements in 34 isolates was performed. First, sequence analysis of the aj1 -LP- fusB region indicated that at least three types were present. Type I contained full-length aj1 , type II contained a partial aj1 truncated from nucleotide position 93 to 421, and type III contained a more truncated aj1 that retained only the last 37 bp. Isolates with type I or type II aj1 displayed slightly higher levels of resistance to fusidic acid (MICs, 8 to 32 μg/ml) than did those with type III aj1 (MICs, 4 to 16 μg/ml). Subsequent sequencing of the flanking regions of fusB from four selected isolates carrying different types of aj1 -LP- fusB regions revealed that the fusB genes were all located on phage-related resistance islands (RIs), referred to as SeRI fusB -2793 , SeRI fusB -704 , SeRI fusB -5907 , and SeRI fusB -7778 , respectively. Among them, three islands (SeRI fusB -2793 , SeRI fusB -704 , and SeRI fusB -5907 ) were located downstream of groEL (corresponding to the 44-min position based on Staphylococcus aureus whole genomic sequences), and one (SeRI fusB -7778 ) was located downstream of rpsR (corresponding to the 8-min position). All of the RIs were inserted into integrase-recognized att sites. Among 34 isolates, the insertion sites of fusB RIs were mostly (28/34, 82%) located downstream of groEL and two were located downstream of rpsR , but four remained unidentified. The pulsotype distribution indicated that fusB -containing S. epidermidis isolates were heterogeneous. In conclusion, the fusB resistance determinant in S. epidermidis was highly associated with phage-related RIs. This is the first report of fusB RI in S. epidermidis .

We determined the groESL sequences of three species of nutritionally variant streptococci ( Abiotrophia defectiva , Granulicatella adiacens , and Granulicatella elegans ) and three Gemella species ( Gemella morbillorum , Gemella haemolysans , and Gemella sanguinis ). The nucleotide sequence similarities between the groES and groEL genes of the above genera were 41.7 to 85.9% and 63.7 to 84.3%, respectively. The intraspecies similarities of groESL sequences for the isolates of Abiotrophia and Granulicatella species were 94.4 to 97.8% for groES and 94.0 to 98.2% for groEL . For Ge. morbillorum and Ge. sanguinis , all strains showed the same groESL spacer length (8 bp), and sequence identities within species were >97.8% for groES and >96.1% for groEL . However, higher intraspecies heterogeneity was observed in Ge. haemolysans . Phylogenetic analysis of groEL sequences separated the 6 isolates of Ge. haemolysans into two subgroups. Among these isolates, three isolates with the same groESL spacer region length (45 bp) clustered together but were distant from the ATCC reference strain (with a spacer length of 8 bp). The remaining three isolates, with a spacer length of 50 or 8 bp, clustered together. Although 16S rRNA gene sequence analysis did not provide enough discrimination for the 6 Ge. haemolysans isolates, rpoB gene sequence analysis supported the subgrouping. Based on the obtained groESL sequences, we developed a multiplex PCR that enables simple, rapid, and accurate identification of Abiotrophia , Granulicatella , and Gemella at the genus level. This assay would be helpful for identifying these fastidious and slow-growing organisms in clinical laboratories.

Background and Objectives Multidrug-resistant (MDR) Pseudomonas aeruginosa infection is becoming a critical problem worldwide. Currently, only limited therapeutic options are available for the treatment of infections caused by MDR P. aeruginosa, therefore, the development of new alternative treatments is needed. Toluidine blue O (TBO) is an effective antibacterial photosensitizing agent against various bacteria. However, reports on antibacterial photosensitization of MDR bacteria are limited. This study aims to determine the in vitro photobactericidal activity of TBO against MDR P. aeruginosa. Study Design/Materials and Methods The efficacy of antibacterial photodynamic inactivation, DNA fragmentation and protein carbonylation of three MDR P. aeruginosa strains and one susceptible strain was compared using TBO as the photosensitizer followed by red light irradiation (630 nm, 90 J/cm2) from a light-emitting diode light source. Subsequently, the efficacy of TBO photodynamic inactivation (TBO-PDI) on 60 MDR strains, including 11 with the efflux pump phenotype and 49 with no pump activity, was tested using the minimum lethal drug concentration (MLC) assay. Results TBO-PDI caused similar bactericidal effect (6–7 logs of killing effect), DNA fragmentation and protein carbonylation in three MDR and one susceptible P. aeruginosa strains. Although the TBO accumulation assay indicated that TBO is a substrate for the efflux pump, TBO-PDI produce similar photobactericidal activity against 60 MDR P. aeruginosa strains, either with or without efflux-pump phenotype, and 19 susceptible strains. Conclusion MDR did not affect the susceptibility of P. aeruginosa strains to TBO-PDI. The efflux pump played an insignificant role in TBO-PDI of MDR P. aeruginosa. Lasers Surg. Med. 41:391–397, 2009. © 2009 Wiley-Liss, Inc.

The sequence diversity of groESL genes among Streptococcus bovis group isolates was analysed, including five reference strains and 36 clinical isolates. Phylogenetic analysis of the groES and groEL sequences showed that the isolates that belonged to the same species or subspecies usually clustered together. The intergenic spacer region between groES and groEL was variable in size (67–342 bp) and sequence and appeared to be a unique marker for species or subspecies determination. Sequence similarities of the groESL genes among species and subspecies ranged from 84.2 to 99.0 % in groES, and from 88.0 to 99.0 % in groEL. Based on the sequences determined, a Streptococcus bovis group-specific PCR assay was developed, which may provide an alternative means of distinguishing the bovis group from other viridans streptococci. Restriction digestion of the amplicon with AclI further differentiated the species and subspecies.

We investigated the sequence and the genetic context of the erm (T) gene in six inducible erythromycin-resistant Streptococcus gallolyticus subsp. pasteurianus (formerly S. bovis biotype II.2) isolates. In all isolates, the erm (T) genes were flanked by two IS 1216V -like elements with the same polarity and were found to be inserted in the chromosome.

Nucleotide sequencing of the fusB -flanking regions in two fusidic acid-resistant Staphylococcus epidermidis isolates with the type IV aj1 -leader peptide (LP)- fusB structure (lacking aj1 ) revealed that their fusB gene was located on novel phage-related islands inserted downstream of smpB and are here referred to as SeRI fusB -3692 and SePI fusB -857 . The novel SePI fusB -857 structure was followed by SeCI 857 , forming a composite pathogenicity island which contained a putative virulence gene, vapE . The linkage of fusB and vapE may contribute to bacterial adaption.

Objectives To determine MICs of fusidic acid for and identify genetic determinants of resistance in Staphylococcus cohnii isolates. Methods Susceptibility to fusidic acid was determined by the standard agar dilution method in 24 S. cohnii subsp. urealyticus clinical isolates, 7 S. cohnii subsp. cohnii clinical isolates and 2 reference strains. Sequencing of a novel resistance determinant, fusF, and its flanking regions was performed by long and accurate PCR and inverse PCR. To evaluate the function of fusF, the MIC of fusidic acid was determined for recombinant Staphylococcus aureus carrying a plasmid expressing fusF. Results A total of 25 S. cohnii subsp. urealyticus (24 clinical isolates and 1 reference strain) and 2 S. cohnii subsp. cohnii displayed low-level resistance to fusidic acid (MICs 2-16 mg/L). Sequencing of a 4259 bp fragment from S. cohnii subsp. urealyticus ATCC 49330 revealed a novel resistance gene, designated fusF, which displayed 70.5% nucleotide and 67.3% amino acid identity to fusD. Expression of fusF in S. aureus confers resistance to fusidic acid. Conclusions A novel FusB-family gene, fusF, was identified as a major resistance determinant in S. cohnii clinical isolates resistant to fusidic acid.

Background/objectives Community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) was recognized as a leading pathogen and has been shown to be genetically different from the health care-associated MRSA (HA-MRSA). Photodynamic therapy (PDT) is considered a potential alternative method for the treatment of resistant bacterial infections, but the effect of PDT on CA-MRSA is unknown. The purpose of this study was to compare the bactericidal effects of toluidine blue O (TBO) on CA-MRSA and HA-MRSA and investigate the photodynamic inactivation effects of TBO (TBO-PDI) against bacterial virulence factors. Materials and methods TBO-PDI effects were determined by measuring the survival fractions for four strains and bactericidal activities for 26 CA-MRSA isolates and 26 HA-MRSA isolates. The influences of TBO-PDI on DNA fragmentation and the activities of protease, lipase, staphylococcal α-hemolysin, and enterotoxin were studied. Results TBO-PDI has effective bactericidal activity against both CA- and HA-MRSA. However, the bactericidal activity of TBO-PDI was significantly higher against HA-MRSA than CA-MRSA isolates. In addition, TBO-PDI treatment using a sublethal TBO concentration led to reduced production of several virulence factors, including protease, lipase, staphylococcal α-hemolysin, and enterotoxin. Conclusion Although TBO-PDI is slightly less effective against CA-MRSA than HA-MRSA isolates, TBO-PDI could reduce the production of virulence factors at a sublethal TBO concentration, which would be beneficial for treating CA-MRSA infections.

Four Gram-staining-positive, catalase-negative, coccoid isolates, designated NTUH_1465T, NTUH_2196, NTUH_4957 and NTUH_5572T, were isolated from human specimens. The four isolates displayed more than 99.6 % 16S rRNA gene sequence similarity with Gemella haemolysans ATCC 10379T, and 96.7 to 98.6 % similarity with Gemella sanguinis ATCC 700632T, Gemella morbillorum ATCC 27824T or Gemella cuniculi CCUG 42726T. However, phylogenetic analysis of concatenated sequences of three housekeeping genes, groEL, rpoB and recA, suggested that the four isolates were distinct from G. haemolysans ATCC 10379T and other species. Isolates NTUH_2196, NTUH_4957 and NTUH_5572T clustered together and formed a stable monophyletic clade. DNA–DNA hybridization values among strains NTUH_1465T and NTUH_5572T and their phylogenetically related neighbours were all lower than 49 %. The four isolates could be distinguished from G. haemolysans and other species by phenotypic characteristics. Based on the phylogenetic and phenotypic results, two novel species Gemella parahaemolysans sp. nov. (type strain NTUH_1465T = BCRC 80365T = JCM 18067T) and Gemella taiwanensis sp. nov. (type strain NTUH_5572T = BCRC 80366T = JCM 18066T) are proposed.

A total of 274 Streptococcus dysgalactiae subsp. equisimilis isolates was analyzed by emm typing and by determining the organization of their mgrC loci. Three of the most frequent emm types were stG485.0 (45/274, 16.4%), stG6.1 (43/274, 15.7%), and stC839.0 (32/274, 11.7%), in decreasing order. The cpdB -positive mgrC locus appears to be predominant in some emm types.

A total of 71 fusidic acid-resistant Staphylococcus aureus (45 methicillin-resistant and 26 methicillin-susceptible) isolates were examined for the presence of resistance determinants. Among 45 fusidic acid-resistant methicillin-resistant S. aureus (MRSA), isolates, 38 (84%) had fusA mutations conferring high-level resistance to fusidic acid (the MIC was ≥128 μg/ml for 22/38), none had fusB , and 7 (16%) had fusC . For 26 fusidic acid-resistant methicillin-susceptible S. aureus (MSSA), only 3 possessed fusA mutations, but 15 (58%) had fusB and 8 (31%) had fusC . Low-level resistance to fusidic acid (MICs ≤ 32 μg/ml) was found in most fusB - or fusC -positive isolates. For 41 isolates (38 MRSA and 3 MSSA), with fusA mutations, a total of 21 amino acid substitutions in EF-G ( fusA gene) were detected, of which R76C, E444K, E444V, C473S, P478S, and M651I were identified for the first time. The nucleotide sequencing of fusB and flanking regions in an MSSA isolate revealed the structure of partial IS 257 - aj1 -LP- fusB - aj2 - aj3 -IS 257 -partial blaZ , which is identical to the corresponding region in pUB101, and the rest of fusB -carrying MSSA isolates also show similar structures. On the basis of spa and staphylococcal cassette chromosome mec element (SCC mec ) typing, two major genotypes, spa type t037-SCC mec type III (t037-III; 28/45; 62%) and t002-II (13/45; 29%), were predominant among 45 MRSA isolates. By pulsed-field gel electrophoresis analysis, 45 MRSA isolates were divided into 12 clusters, while 26 MSSA isolates were divided into 15 clusters. Taken together, the distribution of fusidic acid resistance determinants ( fusA mutations, fusB , and fusC ) was quite different between MRSA and MSSA groups.

A total of 274 Streptococcus dysgalactiae subsp. equisimilis isolates was analyzed by emm typing and by determining the organization of their mgrC loci. Three of the most frequent emm types were stG485.0 (45/274, 16.4%), stG6.1 (43/274, 15.7%), and stC839.0 (32/274, 11.7%), in decreasing order. The cpdB-positive mgrC locus appears to be predominant in some emm types.

We analyzed the occurrence and mechanisms of fusidic acid resistance present in staphylococci isolated from 59 healthy volunteers. The fingers of the volunteers were screened for the presence of staphylococci, and the collected isolates were tested for resistance to fusidic acid. A total of 34 fusidic acid resistant staphylococcal strains (all were coagulase-negative) were isolated from 22 individuals (22/59, 37.3%). Examination of the resistance genes revealed that acquired fusB or fusC was present in Staphylococcus epidermidis, Staphylococcus capitis subsp. urealyticus, Staphylococcus hominis subsp. hominis, Staphylococcus warneri and Staphylococcus haemolyticus. Resistance islands (RIs) carrying fusB were found in S. epidermidis and S. capitis subsp. urealyticus, while staphylococcal chromosome cassette (SCC)-related structures harboring fusC were found in S. hominis subsp. hominis. Genotypic analysis of S. epidermidis and S. hominis subsp. hominis indicated that the fus elements were disseminated in diverse genetic strain backgrounds. The fusC elements in S. hominis subsp. hominis strains were highly homologous to SCCfusC in the epidemic sequence type (ST) 239/SCCmecIII methicillin-resistant S. aureus (MRSA) or the pseudo SCCmec in ST779 MRSA. The presence of acquired fusidic acid resistance genes and their genetic environment in commensal staphylococci suggested that the skin commensal staphylococci may act as reservoir for fusidic acid resistance genes.

Background Staphylococcus lugdunensis is a member of coagulase-negative staphylococci, which has the potential to cause serious infections, such as endocarditis, bone and joint infections, and septicemia. Differences in phenotypic/genotypic characterization may be linked to different diseases. Methods Genotypes of 11 S. lugdunensis isolates from bacteremia were determined by pulsed field gel electrophoresis and accessory gene regulator ( agr ) typing. The SCC mec elements in two oxacillin-resistant isolates were sequenced. Phenotypes were tested by antimicrobial susceptibility testing, biofilm formation assessments, and virulence factor analysis (hemolytic and protease activities). Results Among the 11 isolates, six pulsotypes were found, and seven isolates belonged to two major pulsotypes. Two agr types ( agr-1 sl or agr-2 sl ) were found. The 11 isolates were susceptible to most antimicrobial agents tested. The SCC mec elements in two oxacillin-resistant isolates belonged to the SCC mec type V, but with additional ccrAB2 genes. The agr-2 sl isolates ( n = 7) displayed higher hemolytic and protease activities than the agr-1 sl isolates. All isolates contained the icaA gene but with variable biofilm activities. The results suggest that protein might play an important part in S. lugdunensis biofilms, possibly through an ica -independent pathway. Of the 11 patients with S. lugdunensis bacteremia, one patient had a community-onset infection, and others had a hospital-acquired infection, which were mostly central venous catheter-related infections. Conclusion The 11 S. lugdunensis bacteremia isolates displayed various genotypes and phenotypes. Two oxacillin-resistant isolates contained SCC mec type V and carried additional ccrAB2 genes. Correlation of genotypes and phenotypes with infections needs further studies.