Dissemination of fusidic acid resistance among Staphylococcus aureus clinical isolates

Phenotypic and genotypic characterization of Staphylococcus aureus strains isolated from otitis externa: Emergence of CC30-spa t019-SCCmec IV carrying PVL as major genotype

The increasing emergence of Staphylococcus aureus as the primary causative agent of otitis externa has been noted; however, detailed information regarding the molecular characteristics of these strains in Iran remains scarce. The current study aims to investigate both genotypic and phenotypic attributes of S. aureus strains implicated in ear infections. In the present work, we analyzed 60 S. aureus strains isolated from cases of otitis externa over a period of 45 months. The resistance patterns were determined using disk diffusion and microbroth dilution methods. All S. aureus isolates were confirmed by the nucA polymerase chain reaction assay, and their biofilm production was assessed by a microtiter plate assay. Molecular characterization of the isolates was performed using the staphylococcal cassette chromosome mec, multilocus sequence typing, and staphylococcus protein A typing methods. Overall, the results indicated that 44 out of 60 S. aureus isolates (73.3 %) were methicillin-resistant Staphylococcus aureus. Resistance to mupirocin and vancomycin was observed in 13.3 % and 1.7 % of the tested isolates, respectively. Furthermore, out of the 60 S. aureus isolates, 56 strains (93.4 %) were classified as positive biofilm strains at different levels. Twelve distinct clonal lineages were identified. The vast majority of S. aureus isolates belonged to CC30/ST30-MRSA IV/t019 (41.7 %). Among the 31 strong biofilm producers, the majority (64.5 %) belonged to CC30/ST30-MRSA IV/t019 clone. Biofilm negative isolates belonged to CC22/ST22 (2 isolates), CC8/ST585 (one isolate), and CC8/ST8 (one isolate). Our result revealed that about three-quarters of PVL-positive strains belonged to CC30/ST30. Our data confirmed the presence of MSSA strains among CC30/ST30 and CC22/ST22 isolates. The mupirocin resistant isolates (n = 8) belonged to CC8/ST585-MRSA III/t713 (37.5 %), CC8/ST239-MRSA III/t030 (25 %), CC8/ST8-MRSA IV/t008 (12.5 %), CC8/ST239-MRSA III/t037 (12.5 %), and CC22/ST22-MRSA IV/t790 (12.5 %) lineages. The VRSA strain belonged to the CC8/ST8-MRSA IV/t008 lineage, carrying the vanA determinant. iMLSB phenotypes (n = 14) were distributed across different lineages, including CC30/ST30-MRSA IV/t019 (21.5 %), CC30/ST30-MSSA/t021 (21.5 %), CC22/ST22-MSSA/t005 (14.3 %), CC8/ST239-MRSA III/t030 (14.3 %), CC22/ST22-MSSA/t1869 (7.1 %), CC22/ST22-MRSA IV/t790 (7.1 %), CC8/ST239-MRSA III/t037 (7.1 %), and CC1/ST772-MRSA IV/t10795 (7.1 %). These findings highlight significant genotypic diversity and high biofilm formation among our isolates. The frequent occurrence of the CC/ST30 clone in S. aureus strains isolated from otitis externa reflects the emergence of these lineages as a predominant clone in Iran, posing a significant public health concern.

Genomic Analysis of the Unusual Staphylococcus aureus ST630 Isolates Harboring WTA Glycosyltransferase Genes tarM and tagN

Staphylococcus aureus (S. aureus) can cause a broad spectrum of diseases ranging from skin infections to life-threatening diseases in both community and hospital settings. The surface-exposed wall teichoic acid (WTA) has a strong impact on host interaction, pathogenicity, horizontal gene transfer, and biofilm formation in S. aureus. The unusual S. aureus ST630 strains containing both ribitol-phosphate (RboP) WTA glycosyltransferase gene tarM and glycerol-phosphate (GroP) WTA glycosyltransferase gene tagN have been found recently. Native PAGE analysis showed that the WTA of tagN, tarM-encoding ST630 strains migrated slower than that of non-tagN-encoding ST630 strains, indicating the differences in WTA structure. Some mobile genetic elements (MGEs) such as the unique GroP-WTA biosynthetic gene cluster (SaGroWI), SCCmec element, and prophages that probably originated from the CoNS were identified in tagN, tarM-encoding ST630 strains. The SaGroWI element was first defined in S. aureus ST395 strain, which was refractory to exchange MGEs with typical RboP-WTA expressing S. aureus but could undergo horizontal gene transfer events with other species and genera via the specific bacteriophage Φ187. Overall, our data indicated that this rare ST630 was prone to acquire DNA from CoNS and might serve as a novel hub for the exchange of MGEs between CoNS and S. aureus. IMPORTANCE The structure of wall-anchored glycopolymers wall teichoic acid (WTA) produced by most Gram-positive bacteria is highly variable. While most dominant Staphylococcus aureus lineages produce poly-ribitol-phosphate (RboP) WTA, the tagN, tarM-encoding ST630 lineage probably has a poly-glycerol-phosphate (GroP) WTA backbone like coagulase-negative staphylococci (CoNS). There is growing evidence that staphylococcal horizontal gene transfer depends largely on transducing helper phages via WTA as the receptor. The structural difference of WTA greatly affects the transfer of mobile genetic elements among various bacteria. With the growing advances in sequencing and analysis technologies, genetic analysis has revolutionized research activities in the field of the important pathogen S. aureus. Here, we analyzed the molecular characteristics of ST630 and found an evolutionary link between ST630 and CoNS. Elucidating the genetic information of ST630 lineage will contribute to understanding the emergence and diversification of new pathogenic strains in S. aureus.

The Prevalence and Determinants of Fusidic Acid Resistance Among Methicillin-Resistant Staphylococcus aureus Clinical Isolates in China

The significant increase in resistance of methicillin-resistant Staphylococcus aureus (MRSA) to fusidic acid (FA) is a worrying public concern. However, the data on the prevalence of FA-resistant MRSA isolates in China is still limited. This study aims to investigate the prevalence of FA resistance and resistance determinants among MRSA isolates from six tertiary hospitals in different regions of China between 2016 and 2020. The antimicrobial susceptibility of MRSA isolates was performed by disk diffusion test and broth microdilution method. Whole-genome sequencing was conducted to evaluate the determinants of FA resistance and molecular characterization of FA-resistant MRSA isolates. In this study, a total of 74 (74/457, 16.2%) isolates were identified to be FA-resistant among 457 non-duplicate MRSA isolates. The prevalence of 74 FA-resistant isolates was as follows: Hubei (28/70, 40%), Shanghai (18/84, 21.4%), Jiangxi (7/58, 12.1%), Inner Mongolia Autonomous Region (6/38, 15.8%), Guangdong (12/112, 10.7%), and Sichuan (3/95, 3.2%). The mutations in fusA were present in 79.7% (59/74) of FA-resistant MRSA isolates, with 54 (54/74, 73%) having L461K mutation and conferring high-level resistance [Minimum Inhibitory Concentration (MIC)>128 μg/ml]. Acquired gene, fusB, with low-level resistance (MIC <16 μg/ml) was found in 20.3% (15/74) FA-resistant MRSA isolates. ST5-MRSA-II-t2460 was the most prevalence clone with high-level resistance, accounting for 51.4% (38/74), which was distributed in Hubei (24/28, 85.7%), Inner Mongolia Autonomous Region (4/6, 66.7%), Shanghai (7/18, 38.9%), and Guangdong (3/12, 25%). ST630-t4549 MRSA isolates with low-level resistance were the most common in Jiangxi (3/7, 42.9%) and Sichuan (2/3, 66.7%). In brief, the prevalence of FA resistance among MRSA isolates in China was relatively high with geographic differences. High-level FA resistance was associated mostly with fusA mutations, especially the L461K mutation, whereas fusB usually conferred the low-level resistance to FA. The spread of ST5-MRSA-II-t2460 clone with high-level resistance to FA contributed greatly to the increase of FA-resistant MRSA isolates in most regions, especially in Hubei.

Methicillin-resistant Staphylococcus aureus of the clonal lineage ST5-SCCmecII-t2460 was associated with high mortality in a Wuhan hospital

Methicillin-resistant Staphylococcus aureus (MRSA) is an important human pathogen that can cause serious infectious diseases. An emerging MRSA strain, ST5-SCCmecII spa-type-t2460 (SMRSA), has spread rapidly since its recent emergence in China, but little information is available about this lineage. In this study, 91 MRSA isolates were collected from patients treated in the Zhongnan Hospital, Wuhan University, from 2018 to 2019, and investigated for their molecular characteristics, antibiotic resistance profiles, and clinical characteristics. The predominant lineage, SMRSA, accounted for 37.4% (34/91) of the isolates, followed by ST239-SCCmecIII-t030 (19.8%, 18/91) and ST59-SCCmecIV-t437 (8.8%, 8/91). In contrast to the latter two non-SMRSA (nSMRSA) lineages, which are among the main MRSA found in Chinese settings, SMRSA exhibited small colony variant (SCV) phenotype and had extremely high resistance rates to erythromycin (100.0%), clindamycin (100.0%), levofloxacin (100.0%), tetracycline (97.1%), moxifloxacin (97.1%), and ciprofloxacin (100%), but was more susceptible to rifampicin (resistance rate 3%). The levels of white blood cells (WBC) and procalcitonin (PCT) and the 30-day mortality in patients infected with SMRSA were (12.54 ± 6.61) × 10⁹/L, 0.66 ng/mL, and 52.9%, respectively, which were much higher than those in patients infected with nSMRSA. In addition, patients infected with SMRSA were more frequently admitted to the intensive care unit (ICU) and submitted to invasive procedures than those infected with nSMRSA. In conclusion, SMRSA showed SCV phenotype and exhibited multiple antibiotic-resistance profiles. In this study, SMRSA was associated with serious infections and poor prognosis. Compared with ST239, ST59, or other nSMRSA strains, patients infected with SMRSA strains have higher 30-day mortality, increased levels of inflammatory biomarkers, and more frequent ICU hospitalization and invasive procedures.

The global prevalence of fusidic acid resistance in clinical isolates of Staphylococcus aureus: a systematic review and meta-analysis

BACKGROUND AND AIM

Staphylococcus aureus (S. aureus) is one of the most common pathogens causing nosocomial and community-acquired infections with high morbidity and mortality rates. Fusidic acid has been increasingly used for the treatment of infections due to methicillin-susceptible S. aureus (MSSA) and methicillin-resistant S. aureus (MRSA). The present study aimed to determine the precise prevalence of fusidic acid resistant MRSA (FRMRSA), fusidic acid resistant MSSA (FRMSSA), and total fusidic acid resistant S. aureus (FRSA) on a global scale.

METHODS

Several international databases including Medline, Embase, and the Web of Sciences were searched (2000-2020) to discern studies addressing the prevalence of FRSA, FRMRSA, and FRMSSA. STATA (version14) software was used to interpret the data.

RESULTS

Of the 1446 records identified from the databases, 215 studies fulfilled the eligibility criteria for the detection of FRSA (208 studies), FRMRSA (143 studies), and FRMSSA (71 studies). The analyses manifested that the global prevalence of FRSA, FRMRSA, and FRMSSA was 0.5%, 2.6% and 6.7%, respectively.

CONCLUSION

This meta-analysis describes an increasing incidence of FRSA, FRMSSA, and FRMRSA. These results indicate the need for prudent prescription of fusidic acid to stop or diminish the incidence of fusidic acid resistance as well as the development of strategies for monitoring the efficacy of fusidic acid use.

Fusidic Acid Resistance Determinants in Methicillin-Resistant Staphylococcus aureus Isolated in Kuwait Hospitals

OBJECTIVE

The aim of this study was to investigate the genetic determinants of fusidic acid (FA) resistance in MRSA isolated from patients in Kuwait hospitals.

METHODS

The minimum inhibitory concentration (MIC) of FA was tested with E-test strips. Genetic determinants of FA were determined by PCR and DNA microarray. Staphylococcal protein A gene (spa) typing and DNA microarray analysis were used to study their genetic backgrounds.

RESULTS

The FA MIC ranged from 2 mg/L to >256 mg/L. Of the 97 isolates, 79 (81.4%) harbored fusC, 14 isolates harbored fusA mutations (fusA), and 4 isolates harbored fusB. Isolates with fusA mutations expressed high FA MIC (MIC >256 mg/L), whereas those with fusC and fusB expressed low FA MIC (MIC 2-16 mg/L). The isolates belonged to 23 spa types and 12 clonal complexes (CCs). The major spa types were t688 (n = 25), t311 (n = 14), t860 (n = 8), and t127 (n = 6) which constituted 54.6% of the isolates. The 12 CCs were CC1, CC5, CC8, CC15, CC22, CC80, CC88, and CC97 with CC5 (45.6%) and CC97 (13.2%) as the dominant CCs.

CONCLUSIONS

The MRSA isolates belonged to diverse genetic backgrounds with the majority carrying the fusC resistance determinants. The high prevalence of FA resistance belonging to diverse genetic backgrounds warrants a review of FA usage in the country to preserve its therapeutic benefits.

Outbreak of community-acquired Staphylococcus aureus skin infections in an Australian professional football team

OBJECTIVES

Skin and soft tissue infections commonly affect athletes and can lead to cluster outbreaks if not managed appropriately. We report the findings of an investigation into an outbreak of community-acquired Staphylococcus aureus infection in an Australian professional football team.

DESIGN

Retrospective cross-sectional study.

METHODS

Nose, axilla, groin and throat swab were collected from 47 participants. MRSA and MSSA isolates underwent antibiotic susceptibility testing, binary typing and whole genome sequencing. Infection control practitioners (ICPs) investigated the training grounds for risk factors in the transmission of S. aureus.

RESULTS

Almost half of the participants (n=23, 48.9%) were found to be colonised with MSSA. An outbreak cluster of MRSA ST5 closely related to the fusidic acid-resistant New Zealand NZAK3 clone was identified in a group of four players. MSSA ST15 and MSSA ST291 strains were found to have colonised and spread between two and five players, respectively. All participants were advised to undergo decolonisation treatment consisting of 4% chlorhexidine body wash and mupirocin nasal ointment for ten days. The ICP team identified several unhygienic practices within the club's shared facilities that may have played a role in the transmission of S. aureus.

CONCLUSIONS

We report for the first time a community-associated S. aureus outbreak involving the highly successful fusidic acid-resistant MRSA ST5 clone in a professional football club associated with inadequate hygiene procedures. Management and prevention of S. aureus relies heavily on hygiene education and adherence to personal and environmental hygiene practices and policies.

Genetic analysis of methicillin‐susceptible Staphylococcus aureus clinical isolates: High prevalence of multidrug‐resistant ST239 with strong biofilm‐production ability

Background

The distributions of methicillin‐susceptible Staphylococcus aureus (MSSA) are divers geographically with different genetic backgrounds. Data related to molecular characteristics of MSSA compare to methicillin‐resistant Staphylococcus aureus (MRSA) is sparse.

Methods

In this cross‐sectional study, antimicrobial susceptibility testing, virulence genes analysis, biofilm formation, accessory gene regulator (agr) typing, and multilocus sequence typing (MLST) characterized on 75 MSSA isolates.

Results

Multidrug‐resistance MSSA was found to be 84%. Forty‐eight (64%) isolates were toxinogenic with 34 and 14 isolates carrying pvl and tst representing 45.3% and 18.7%. The most common SE genes were sed (20%), sec (16%), and sea (16%). Fifty‐five (73.3%) isolates were confirmed as biofilm producer with a markedly high prevalence of fnbA (93.3%), fnbB (86.7%), icaA (65.3%), icaD (53.3%), can (24%), ebp (10.7%), and bap (1.3%). A total of 3 agr types (I, 73.3%; III, 16%; II, 10.7%) and 4 clonal complexes (CCs) and sequence types (STs), namely CC8/ST293 (45.3%), CC/ST22 (28%), CC/ST30 (16%), and CC/ST5 (10.7%) were detected in this study. All the high and low‐level mupirocin resistance strains belonged to ST239 and ST22 strains, respectively. All the fusidic acid‐resistant isolates carried fusC and belonged to ST30.

Conclusions

These findings indicated that ST239 with strong biofilm production ability is the most common type in MSSA strains isolated from patients. It seems that the antimicrobial resistance profiles, toxin, and biofilm formation were closely associated with specific STs. Further studies are required to identify and control of these clonal lineages in our area.

A Novel Promazine Derivative Shows High in vitro and in vivo Antimicrobial Activity Against Staphylococcus aureus

The emergence of multidrug-resistant bacteria constitutes a significant public health issue worldwide. Consequently, there is an urgent clinical need for novel treatment solutions. It has been shown in vitro that phenothiazines can act as adjuvants to antibiotics whereby the minimum inhibitory concentration (MIC) of the antibiotic is decreased. However, phenothiazines do not perform well in vivo, most likely because they can permeate the blood-brain (BBB) barrier and cause severe side-effects to the central nervous system. Therefore, the aim of this study was to synthesize a promazine derivate that would not cross the BBB but retain its properties as antimicrobial helper compound. Surprisingly, in vitro studies showed that the novel compound, JBC 1847 exhibited highly increased antimicrobial activity against eight Gram-positive pathogens (MIC, 0.5-2 mg/L), whereas a disc diffusion assay indicated that the properties as an adjuvant were lost. JBC 1847 showed significant (P < 0.0001) activity against a Staphylococcus aureus strain compared with the vehicle, in an in vivo wound infection model. However, both in vitro and in silico analyses showed that JBC 1847 possesses strong affinity for human plasma proteins and an Ames test showed that generally, it is a non-mutagenic compound. Finally, in silico predictions suggested that the compound was not prone to pass the BBB and had a suitable permeability to the skin. In conclusion, JBC 1847 is therefore suggested to hold potential as a novel topical agent for the clinical treatment of S. aureus skin and soft tissue infections, but pharmacokinetics and pharmacodynamics need to be further investigated.

Molecular Characteristics, Antimicrobial Resistance and Virulence Gene Profiles of Staphylococcus aureus Isolates from Wuhan, Central China

PURPOSE

This study aimed to investigate the molecular characteristics, antimicrobial resistance and virulence genes profiles of S. aureus isolates from Wuhan, central China.

MATERIALS AND METHODS

A total of 302 non-duplicate S. aureus isolates were collected successively during January-December 2018 and subjected to multi-locus sequence typing (MLST), staphylococcal protein A (spa) typing and Panton-Valentine leucocidin (PVL) and staphylococcal enterotoxin A, B, C, D, E, G, H and I (sea, seb, sec, sed, see, seg, seh and sei) detection. All methicillin-resistant S. aureus (MRSA) isolates were additionally subjected to staphylococcal chromosomal cassette mec(SCCmec) typing.

RESULTS

Of the 302 S. aureus isolates, 131 were categorised as MRSA, yielding a rate 1.4 times the average rate in China during 2018 (43.4% vs 30.9%). Thirty-one sequence types (STs) and 82 spa types were identified. The most prevalent clones were ST5-t2460 (10.9%), ST239-t030 (9.3%), ST188-t189 (7.9%) and ST59-t437 (6.3%). Notably, the continued prevalence of ST239-t030 in Wuhan differs from other areas in China. SCCmec types and subtypes I, II, III, IVa and V were present in 0.8%, 36.6%, 26.0%, 20.6% and 8.4% of MRSA isolates. A comprehensive analysis identified ST5-t2460-SCCmec II (25.2%,), ST239-t030-SCCmec III (19.8%) and ST59-t437-SCCmec IVa (7.6%) as the major clones among MRSA isolates. The genes pvl, sea, seb, sec, sed, see, seg, seh and sei were detected at respective frequencies of 11.9%, 42.1%, 49.7%, 45.0%, 20.9%, 33.8%, 60.5%, 25.8% and 66.9%.

CONCLUSION

ST239-t030 remains one of the most prevalent clones in S. aureus isolates from Wuhan, leading us to conclude that S. aureus isolates from Wuhan possess unique molecular characteristics. The S. aureus isolates also exhibit unique antimicrobial resistance profiles and harbour relatively high numbers of enterotoxin virulence genes, compared with other reports from China.

Prevalence and molecular characterization of methicillin-resistant Staphylococcus aureus with mupirocin, fusidic acid and/or retapamulin resistance

Background

The data on the prevalence of resistance to mupirocin (MUP), fusidic acid (FA) and retapamulin (RET) in methicillin-resistant Staphylococcus aureus (MRSA) from China are still limited. This study aimed to examine these three antibiotics resistance in 1206 MRSA clinical isolates from Eastern China. Phenotypic MUP, FA and RET resistance was determined by minimum inhibitory concentrations (MICs), and genotypic by PCR and DNA sequencing of the mupA/B, fusB-D, cfr, vgaA/Av/A_LC/B/C/E, lsaA-C/E and salA and mutations in ileS, fusA/E, rplC, and 23S RNA V domain. The genetic characteristics of resistance isolates were conducted by pulsed field gel electrophoresis (PFGE) and multilocus sequence typing (MLST).

Results

Overall MRSA MUP, FA and RET resistance was low (5.1, 1.0 and 0.3%, respectively). MupA was the mechanism of high-level MUP resistance. All low-level MUP resistance isolates possessed an equivocal mutation N213D in IleS; of these, 2 reported an additional V588F mutation with an impact on the Rossman fold. FusA mutations, such as L461K, H457Q, H457Y and V90I were the primary FA mechanisms among high-level resistance isolates, most of which also contained fusC; however, all low-level resistance strains carried fusB. Except lsaE gene detected in one isolate, no other resistance mechanisms tested were found among RET-resistant isolates. Additionally, sixteen PFGE types (A-P) were observed, among which type B was the most common (49/76, 64.5%), followed by types E and G (4/76, 5.3% each) and types C and M (3/76, 3.9% each). All resistant strains were divided into 15 ST types by MLST. ST764 (24/76, 31.6%), ST630 (11/76, 14.5%), ST239 (9/76, 11.8%) and ST5 (7/76, 9.2%) were the major types. PFGE type B isolates with the aforementioned STs were mainly found in mupirocin resistant isolates.

Conclusions

MUP, FA and RET exhibited highly activity against the MRSA isolates. Acquired genes and chromosome-borne genes mutations were responsible for MUP and FA resistance; however, the mechanism for some RET-resistant isolates remains to be further elucidated. Also, the surveillance to MUP in MRSA should be strengthened to prevent elevated resistance due to the expansion of clones.

Prevalence, Genetic Diversity, and Temporary Shifts of Inducible Clindamycin Resistance Staphylococcus aureus Clones in Tehran, Iran: A Molecular-Epidemiological Analysis From 2013 to 2018

The prevalence of Staphylococcus aureus as an aggressive pathogen resistant to multiple antibiotics causing nosocomial and community-acquired infections is increasing with limited therapeutic options. Macrolide-lincosamide streptogramin B (MLSB) family of antibiotics represents an important alternative therapy for staphylococcal infections. This study was conducted over a period of five years from August 2013 to July 2018 to investigate the prevalence and molecular epidemiology in Iran of inducible resistance in S. aureus. In the current study, 126 inducible methicillin-resistant S. aureus (MRSA) (n = 106) and methicillin-sensitive S. aureus (MSSA) (n = 20) isolates were characterized by in vitro susceptibility analysis, resistance and virulence encoding gene distribution, phenotypic and genotypic analysis of biofilm formation, prophage typing, S. aureus protein A locus (spa) typing, staphylocoagulase (SC) typing, staphylococcal cassette chromosome mec (SCCmec) typing, and multilocus sequence typing. Of the 126 isolates, 76 (60.3%) were classified as hospital onset, and 50 (39.7%) were classified as community onset (CO). Biofilm formation was observed in 97 strains (77%). A total of 14 sequence types (STs), 26 spa types, 7 coagulase types, 9 prophage types, 3 agr types (no agr IV), and 9 clonal complexes (CCs) were identified in this study. The prevalence of the inducible MLSB (iMLSB) S. aureus increased from 7.5% (25/335) to 21.7% (38/175) during the study period. The iMLSB MRSA isolates were distributed in nine CCs, whereas the MSSA isolates were less diverse, which mainly belonged to CC22 (7.95%) and CC30 (7.95%). High-level mupirocin-resistant strains belonged to ST85-SCCmec IV/t008 (n = 4), ST5-SCCmec IV/t002 (n = 4), ST239-SCCmec III/t631 (n = 2), and ST8-SCCmec IV/t064 (n = 2) clones, whereas low-level mupirocin-resistant strains belonged to ST15-SCCmec IV/t084 (n = 5), ST239-SCCmec III/t860 (n = 3), and ST22-SCCmec IV/t790 (n = 3) clones. All the fusidic acid–resistant iMLSB isolates were MRSA and belonged to ST15-SCCmec IV/t084 (n = 2), ST239-SCCmec III/t030 (n = 2), ST1-SCCmec V/t6811 (n = 1), ST80-SCCmec IV/t044 (n = 1), and ST59-SCCmec IV/t437 (n = 1). The CC22 that was predominant in 2013–2014 (36% of the isolates) had almost disappeared in 2017–2018, being replaced by the CC8, which represented 39.5% of the 2017–2018 isolates. This is the first description of temporal shifts of iMLSB S. aureus isolates in Iran that identifies predominant clones and treatment options for iMLSB S. aureus–related infections.

Molecular Characterization, Drug Resistance and Virulence Analysis of Constitutive and Inducible Clindamycin Resistance Staphylococcus aureus Strains Recovered from Clinical Samples, Tehran - Iran

Background

Macrolide-lincosamide streptogramin B family is one of the important alternative antibiotics for treating staphylococcal infections. The aim of this study was to determine the characteristics and prevalence of antibiotic resistance genes in different coagulase types of clinical Staphylococcus aureus strains.

Methods

In the present study, 86 isolates with different phenotypes of MLS_B resistance were investigated. In vitro susceptibility was assessed by the disk diffusion and broth microdilution methods. PCR assays were used to detect resistance-related genes. Coagulase and SCCmec types were identified by multiplex PCR assay.

Results

The prevalences of constitutive MLS_B, inducible MLS_B, and MS phenotypes were found to be 23%, 14.2%, and 4.9%, respectively. The rates of resistance to mupirocin, fusidic acid, and tigecycline were found to be 9.3%, 4.6%, and 2.3%, respectively. The top three predominant resistance genes were mecA, tet(M), erm(C) representing 75.6, 50, and 40.7% of isolates. mupA (7%), fusB (3.5%), and fusC (1.2%) genes were also detected among tested isolates. Coagulase types were mainly type II (34.9%), followed by III (32.6%), V (20.9%), and I (11.6%).

Conclusion

These findings indicated high resistance rate and low genetic variability with the prominence of coa type II, highlighting the particular importance of diagnosis of these strains to avoid treatment failure.

Coagulase-negative staphylococci carrying cfr and PVL genes, and MRSA/MSSA-CC398 in the swine farm environment

This work aimed at characterizing four Staphylococcus aureus and 68 coagulase-negative staphylococci (CoNS), recovered from the air and liquid manure tank of two swine farms with intensive- and semi-extensive-production types, for their antimicrobial resistance pheno-/genotypes and their virulence gene content. Molecular typing was performed by spa typing, MLST, agr typing, and SCCmec typing, where applicable. Conjugation experiments were performed to assess the transferability of the linezolid resistance gene cfr, and its genetic environment was determined by Whole-Genome-Sequencing. The four S. aureus (intensive-production farm, IP-farm) were typed as t011-agrI-CC398-ST398, were scn-negative and two of them were methicillin-resistant (MRSA) with the mecA gene (SCCmec-V). Multidrug resistance was seen in 87 % of the CoNS. Statistically significant differences among the antimicrobial resistance rates of CoNS from the two farms were observed for cefoxitin, aminoglycosides, tetracycline, ciprofloxacin and trimethoprim-sulfamethoxazole. Eight methicillin-resistant CoNS, which were recovered from the IP-farm, carried the mecA gene. One S. simulans isolate was PVL-positive and three S. cohnii eta-positive. One S. equorum and one S. arlettae showed linezolid resistance and carried the cfr gene (IP-farm), which was non-transferable by conjugation into S. aureus. The cfr genetic context in both isolates was identical, with the lsa(B) gene located upstream of cfr. The environment of swine farms might contribute to the dissemination of CoNS that show multidrug resistance and harbor important virulence factors.

Common Community-acquired Bacterial Skin and Soft-tissue Infections in Children: an Intersociety Consensus on Impetigo, Abscess, and Cellulitis Treatment

PURPOSE

The main objective of this article was to offer practical suggestions, given the existing evidence, for identifying and managing bacterial impetigo, abscess, and cellulitis in ambulatory and hospital settings.

METHODS

Five Italian pediatric societies appointed a core working group. In selected conditions, specially trained personnel evaluated quality assessment of treatment strategies according to the Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) methodology. Only randomized controlled trials (RCTs) and observational studies were included for quality assessment according to the GRADE methodology. MEDLINE, Ovid MEDLINE, EMBASE, and Cochrane Library databases were searched with a strategy combining MeSH and free text terms.

FINDINGS

The literature review included 364 articles focusing on impetigo, skin abscess, and cellulitis/orbital cellulitis. The articles included for quality assessment according to the GRADE methodology for impetigo comprised 5 RCTs and 1 observational study; for skin abscess, 10 RCTs and 3 observational studies were included; for cellulitis and erysipelas, 5 RCTs and 5 observational studies were included; and for orbital cellulitis, 8 observational studies were included. Recommendations were formulated according to 4 grades of strength for each specific topic (impetigo, skin abscesses, cellulitis, and orbital cellulitis). Where controversies arose and expert opinion was considered fundamental due to lack of evidence, agreement according to Delphi consensus recommendations was included.

IMPLICATIONS

Based on a literature review and on local epidemiology, this article offers practical suggestions for use in both ambulatory and hospital settings for managing the most common bacterial SSTIs.

Low prevalence of mupirocin resistance among Staphylococcus aureus clinical isolates from a Chinese tertiary hospital

Between September 2013 and March 2016, 26 (1.95 %) of 1333 Staphylococcus aureus clinical isolates from a Chinese hospital were found to be resistant to mupirocin, including 18 (1.35 %) with high-level mupirocin resistance and 8 (0.6 %) with low-level mupirocin resistance. Among the 18 isolates with high-level mupirocin resistance, 17 were associated with plasmid-mediated mupA. Meanwhile, the 8 isolates with low-level mupirocin resistance were shown to have a V588F mutation in ileS. A total of 14 sequence types (STs) and 18 spa types were identified. All four isolates with t062 belonged to ST965. Three ST5-MRSA-SCCmec II were linked to t311, which was not previously reported. Furthermore, ST764-MRSA-SCCmec II-t002, exclusively found in Japan before, was identified in this study. In conclusion, we observed relatively low prevalence of mupirocin resistance among S. aureus with considerable heterogeneity in East China. Newly emerging MRSA clones with high-level mupirocin resistance should be of concern.

Distribution of the Most Prevalent Spa Types among Clinical Isolates of Methicillin-Resistant and -Susceptible Staphylococcus aureus around the World: A Review

Background:Staphylococcus aureus, a leading cause of community-acquired and nosocomial infections, remains a major health problem worldwide. Molecular typing methods, such as spa typing, are vital for the control and, when typing can be made more timely, prevention of S. aureus spread around healthcare settings. The current study aims to review the literature to report the most common clinical spa types around the world, which is important for epidemiological surveys and nosocomial infection control policies.

Methods: A search via PubMed, Google Scholar, Web of Science, Embase, the Cochrane library, and Scopus was conducted for original articles reporting the most prevalent spa types among S. aureus isolates. The search terms were “Staphylococcus aureus, spa typing.”

Results: The most prevalent spa types were t032, t008 and t002 in Europe; t037 and t002 in Asia; t008, t002, and t242 in America; t037, t084, and t064 in Africa; and t020 in Australia. In Europe, all the isolates related to spa type t032 were MRSA. In addition, spa type t037 in Africa and t037and t437 in Australia also consisted exclusively of MRSA isolates. Given the fact that more than 95% of the papers we studied originated in the past decade there was no option to study the dynamics of regional clone emergence.

Conclusion: This review documents the presence of the most prevalent spa types in countries, continents and worldwide and shows big local differences in clonal distribution.

Recommendations for approaches to meticillin-resistant staphylococcal infections of small animals: diagnosis, therapeutic considerations and preventative measures.: Clinical Consensus Guidelines of the World Association for Veterinary Dermatology

BACKGROUND

Multiple drug resistance (MDR) in staphylococci, including resistance to the semi-synthetic penicillinase-resistant penicillins such as meticillin, is a problem of global proportions that presents serious challenges to the successful treatment of staphylococcal infections of companion animals.

OBJECTIVES

The objective of this document is to provide harmonized recommendations for the diagnosis, prevention and treatment of meticillin-resistant staphylococcal infections in dogs and cats.

METHODS

The authors served as a Guideline Panel (GP) and reviewed the literature available prior to September 2016. The GP prepared a detailed literature review and made recommendations on selected topics. The World Association of Veterinary Dermatology (WAVD) provided guidance and oversight for this process. A draft of the document was presented at the 8th World Congress of Veterinary Dermatology (May 2016) and was then made available via the World Wide Web to the member organizations of the WAVD for a period of three months. Comments were solicited and posted to the GP electronically. Responses were incorporated by the GP into the final document.

CONCLUSIONS

Adherence to guidelines for the diagnosis, laboratory reporting, judicious therapy (including restriction of use policies for certain antimicrobial drugs), personal hygiene, and environmental cleaning and disinfection may help to mitigate the progressive development and dissemination of MDR staphylococci.

Dissemination of macrolides, fusidic acid and mupirocin resistance among Staphylococcus aureus clinical isolates

As an increasingly common cause of skin infections worldwide, the prevalence of antibiotic-resistant Staphylococcus aureus (S. aureus) across China has not been well documented. This literature aims to study the resistance profile to commonly used antibiotics, including macrolides, fusidic acid (FA) and mupirocin, and its relationship to the genetic typing in 34 S. aureus strains, including 6 methicillin-resistant S. aureus (MRSA), isolated from a Chinese hospital. The MIC results showed 27 (79.4%), 1 (2.9%) and 6 (17.6%) isolates were resistant to macrolides, FA and mupirocin, respectively. Among 27 macrolide-resistant S. aureus isolates, 5 (18.5%) were also resistant to mupirocin and 1 (3.7%) to FA. A total of 13 available resistant genes were analyzed in 28 antibiotic-resistant strains using polymerase chain reaction (PCR). The positive rates of macrolide-resistant ermA, ermB, ermC, erm33 and low level mupirocin-resistant ileS mutations were 11.1%, 25.9%, 51.9%, 7.4% and 100%, respectively. Other determinants for FA- and high level mupirocin-resistance were not found. The results of multilocus sequence typing (MLST) and pulsed field gel electrophoresis (PFGE) revealed 13 sequence types (STs) and 18 clusters in 23 resistant gene positive S. aureus isolates. Among these STs, ST5 was most prevalent, accounting for 18.2%. Notably, various clusters were found with similar resistance phenotype and genotype, exhibiting a weak genetic relatedness and high genetic heterogeneities. In conclusion, macrolides, especially erythromycin, are not appropriate to treat skin infections caused by S. aureus, and more effective measures are required to reduce the dissemination of macrolides, FA and mupirocin resistance of the pathogen.