Mupirocin-Resistant Staphylococcus aureus in Iran: A Biofilm Production and Genetic Characteristics

The spread of mupirocin-resistant Staphylococcus aureus strains in hospitals and communities is a universal challenge. Limited data is available on the genetic features of high-level mupirocin resistant- (HLMUPR-) S. aureus isolates in Tehran. In the present research, we investigated 48 high-level mupirocin resistance S. aureus by antimicrobial activity, virulence analysis, biofilm formation, multilocus sequence typing (MLST), and staphylocoagulase (SC) typing. All the HLMUPR strains were positive for mupA gene. The frequency of multidrug resistance was 97.9%. Twenty-one (43.8%) were toxinogenic with 14 producing pvl (29.2%), 5 tst (10.4%), and two eta (4.2%). Among the HLMUPR isolates, biofilm production was detected in 45 (89.6%) isolates with complete dominance clfB, clfA genes, and a noticeably high frequency fnbA (95.8%), followed by fnbB (93.8%), eno and icaD (each 83.3%), sdrC (81.3%), ebps (79.2%), icaA (75%), sdrD (66.7%), fib (60.4%), sdrE (50%), cna (41.7%), and bap (4.2%). Coagulase typing distinguished isolates into four genotypic patterns including III (50%), II (27.1%), and type IVa (22.9%). A total of three clonal complexes (CCs) and 4 sequence types (STs) including CC/ST22 as the most prevalent (52.1%), CC8/ST239 (20.8%), CC/ST8 (16.7%), and CC/ST5 (10.4%) were identified in current work. According to our analysis, nonbiofilm producer isolates belonged to CC8/ST239 (6.3%) and CC/ST8 (4.2%). Fusidic acid-resistant isolates belonged to CC/ST45 ( n = 3 ) and CC8/ST239 ( n = 1 ). Observations highlighted the circulation of the CC/ST22 HLMUPR S. aureus strains with strong biofilm-production ability in our hospitals, indicating the possibility of transmission of this type between community and hospital.

The antimicrobial activity of zinc against group B Streptococcus is strain-dependent across diverse sequence types, capsular serotypes, and invasive versus colonizing isolates

Background Streptococcus agalactiae or Group B Streptococcus (GBS) is an encapsulated gram-positive bacterial pathobiont that commonly colonizes the lower gastrointestinal tract and reproductive tract of human hosts. This bacterium can infect the gravid reproductive tract and cause invasive infections of pregnant patients and neonates. Upon colonizing the reproductive tract, the bacterial cell is presented with numerous nutritional challenges imposed by the host. One strategy employed by the host innate immune system is intoxication of bacterial invaders with certain transition metals such as zinc. Methodology Previous work has demonstrated that GBS must employ elegant strategies to circumnavigate zinc stress in order to survive in the vertebrate host. We assessed 30 strains of GBS from diverse isolation sources, capsular serotypes, and sequence types for susceptibility or resistance to zinc intoxication. Results Invasive strains, such as those isolated from early onset disease manifestations of GBS infection were significantly less susceptible to zinc toxicity than colonizing strains isolated from rectovaginal swabs of pregnant patients. Additionally, capsular type III (cpsIII) strains and the ST-17 and ST-19 strains exhibited the greatest resilience to zinc stress, whereas ST-1 and ST-12 strains as well as those possessing capsular type Ib (cpsIb) were more sensitive to zinc intoxication. Thus, this study demonstrates that the transition metal zinc possesses antimicrobial properties against a wide range of GBS strains, with isolation source, capsular serotype, and sequence type contributing to susceptibility or resistance to zinc stress.

First National Genomic Epidemiological Study of Neisseria gonorrhoeae Strains Spreading Across Sweden in 2016

The increasing transmission and antimicrobial resistance (AMR) in Neisseria gonorrhoeae is a global health concern with worrying trends of decreasing susceptibility to also the last-line extended-spectrum cephalosporin (ESC) ceftriaxone. A dramatic increase of reported gonorrhea cases has been observed in Sweden from 2016 and onward. The aim of the present study was to comprehensively investigate the genomic epidemiology of all cultured N. gonorrhoeae isolates in Sweden during 2016, in conjunction with phenotypic AMR and clinical and epidemiological data of patients. In total, 1279 isolates were examined. Etest and whole-genome sequencing (WGS) were performed, and epidemiological data obtained from the Public Health Agency of Sweden. Overall, 51.1%, 1.7%, and 1.3% resistance to ciprofloxacin, cefixime, and azithromycin, respectively, was found. No isolates were resistant to ceftriaxone, however, 9.3% of isolates showed a decreased susceptibility to ceftriaxone and 10.5% to cefixime. In total, 44 penA alleles were found of which six were mosaic (n = 92). Using the typing schemes of MLST, NG-MAST, and NG-STAR; 133, 422, and 280 sequence types, respectively, and 93 NG-STAR clonal complexes were found. The phylogenomic analysis revealed two main lineages (A and B) with lineage A divided into two main sublineages (A1 and A2). Resistance and decreased susceptibility to ESCs and azithromycin and associated AMR determinants, such as mosaic penA and mosaic mtrD, were predominantly found in sublineage A2. Resistance to cefixime and azithromycin was more prevalent among heterosexuals and MSM, respectively, and both were predominantly spread through domestic transmission. Continuous surveillance of the spread and evolution of N. gonorrhoeae, including phenotypic AMR testing and WGS, is essential for enhanced knowledge regarding the dynamic evolution of N. gonorrhoeae and gonorrhea epidemiology.

EnteroBase: Hierarchical clustering of 100,000s of bacterial genomes into species/sub-species and populations

The definition of bacterial species is traditionally a taxonomic issue while defining bacterial populations is done with population genetics. These assignments are species specific, and depend on the practitioner. Legacy multilocus sequence typing is commonly used to identify sequence types (STs) and clusters (ST Complexes). However, these approaches are not adequate for the millions of genomic sequences from bacterial pathogens that have been generated since 2012. EnteroBase (http://enterobase.warwick.ac.uk) automatically clusters core genome MLST alleles into hierarchical clusters (HierCC) after assembling annotated draft genomes from short read sequences. HierCC clusters span core sequence diversity from the species level down to individual transmission chains. Here we evaluate the ability of HierCC to correctly assign 100,000s of genomes to the species/subspecies and population levels for Salmonella, Clostridoides, Yersinia, Vibrio and Streptococcus. HierCC assignments were more consistent with maximum-likelihood super-trees of core SNPs or presence/absence of accessory genes than classical taxonomic assignments or 95% ANI. However, neither HierCC nor ANI were uniformly consistent with classical taxonomy of Streptococcus. HierCC was also consistent with legacy eBGs/ST Complexes in Salmonella or Escherichia and revealed differences in vertical inheritance of O serogroups. Thus, EnteroBase HierCC supports the automated identification of and assignment to species/subspecies and populations for multiple genera.

Phenotypic and Molecular Characteristics of the MDR Efflux Pump Gene-Carrying Stenotrophomonas maltophilia Strains Isolated in Warsaw, Poland

An increase of nosocomial infections caused by Stenotrophomonas maltophilia strains has recently been observed all over the world. The isolation of these bacteria from the blood is of particular concern. In this study we performed the phenotypic and genotypic characterization of 94 S. maltophilia isolates, including isolates from patients hospitalized in a tertiary Warsaw hospital (n = 79) and from outpatients (n = 15). All isolates were found to be susceptible to trimethoprim-sulfamethoxazole and minocycline, while 44/94 isolates demonstrated a reduction in susceptibility to levofloxacin. A large genetic variation was observed among the isolates tested by pulsed-field gel electrophoresis. A clonal relationship with 100% similarity was observed between isolates within two sub-pulsotypes: the first included nine bloodstream isolates and the second involved six. Multilocus sequence typing showed two new sequence types (ST498 and ST499) deposited in public databases for molecular typing. Moreover, the presence of genes encoding ten different efflux pumps from the resistance-nodulation-division family and the ATP-binding cassette family was shown in the majority of the 94 isolates. The obtained knowledge about the prevalence of efflux pump genes in clinical S. maltophilia strains makes it possible to predict the scale of the risk of resistance emergence in strains as a result of gene overexpression.

Genome analysis of Klebsiella oxytoca complex for antimicrobial resistance and virulence genes

Klebsiella oxytoca complex comprises nine closely-related species causing human infections. We curated genomes labeled Klebsiella (n=14,256) in GenBank and identified 588 belonging to the complex, which were examined for precise species, sequence types, K- and O-antigen types, virulence and antimicrobial resistance genes. The complex and Klebsiella pneumoniae share many K- and O-antigen types. Of the complex, K. oxytoca and Klebsiella michiganensis appear to carry more virulence genes and be more commonly associated with human infections.

Characterization of virulent Escherichia coli strains isolated from patients with urological infection

Objective. Urinary tract infections (UTIs) caused by uropathogenic Escherichia coli (UPEC) affect 150 million people annually.Purpose: Characteristics of non-hospital strains of UPEC isolated from patients with UTI in Yaroslavl in 2016– 2017.Materials and methods. Susceptibility of UPEC strains (n = 20) to antibacterials was measured by the serial dilution method; the antibiotic resistance and virulence genes, phylogroups, O-serogroups and sequence types were identified by PCR and whole genome sequencing. The virulence of the strains was studied using the model of Galleria mellonella larvae.Results. UPEC strains were classified as resistant (n = 11) and multi-drug resistant (n = 9) pathogens. Betalactamase genes blaTEM (n = 10), blaCTX-M (n = 6), class 1 integrons (n = 8), and gene cassettes dfrA17-aadA5 (n = 2), dfrA1 (n = 1) and aacA4-cmlA1 (n = 1) were identified. UPEC-virulence genetic determinants coding adhesins fimH, papG, sfaS, focG, afa/draBC, csgA, siderophores iroN, fyuA, iutA, counteracting factors of host immunity ompT, traT, toxins hlyA, cnf1, usp, capsule transporter kpsMTII, colicin cvaC, and pathogenicity islands I536, II536, III536, IV536, IIJ96 и IICFT073 were detected. Highly virulent and slightly virulent for G. mellonella larvae UPEC strains were obtained with LD50 104–105 and 106–107 CFU, respectively. The phylogroups A, B1, B2, E and F, serogroups О2, О4, О6, O9, O11, О15, О18, О25, О75 and O89, known sequence types ST14, ST58, ST69, ST73, ST93, ST127, ST131, ST-141, ST165, ST297, ST457, ST537, ST744, ST1434 and novel ST9239 and ST10102 were revealed.Conclusions. The identified genetic diversity of non-hospital UPEC strains is consistent with the observed global trend in the spread of human pathogens, which are characterized with both high virulence and multiple drug resistance. This makes possible to assess prospectively the current epidemiological situation, give a forecast for its development in the future, as well as determine the optimal therapeutic options.

Phenotypic profile of priority multiresistant Аcinetobacter baumannii sequence types (ST 1167, ST 944, ST 208)

Introduction. About 1,000,000 cases of infections caused by Acinetobacter spp. per year are registered globally, making up 1.8% of all the cases of hospital-acquired infections. In compliance with long-term studies carried out in in this country and abroad, Acinetobacter baumannii is a clinically important representative of the Acinetobacter genus. Intraspecific typing of microorganisms is an integral part of a clinical microbiologist's contribution to scoring the outbreaks of purulent-septic infections within the sphere of HAI surveillance. Most of the practicing microbiological laboratories cannot use genotypic typing methods because of their high costs.Objective. Developing a test panel for intraspecific identification of A. baumannii sequence types (ST 1167, ST 944, ST 208) based on their phenotypic properties.Materials and methods. Intraspecific membership of 74 A. baumannii strains obtained from four multipurpose health settings of a large industrial centre was studied using a genetic method (multilocus sequence typing) and a suite of phenotypic methods (biochemical tests, biofilmogenous capacity, growth inhibition zones to antibacterial drugs, sensitivity to aniline dyes, disinfectants and Acinetobacter bacteriophage) was studied.Results. Phenotypic features of three predominant A. baumannii sequence types (ST 1167, 944, 208) were determined.Discussion. An efficacious economy set of differentiating tests allowing identification of intraspecific features of A. baumannii multiresistant strains was сreated.Conclusion. The test panel will enable the laboratories that cannot use sequencing methods to conduct intraspecific differentiation of common A. baumannii sequence types as part of microbiological monitoring.

Extensive outbreak of colistin resistant, carbapenemase (blaOXA-48, blaNDM) producing Klebsiella pneumoniae in a large tertiary care hospital, India

Background Extensive drug resistance in Klebsiella pneumoniae (K. pneumoniae) causing major outbreaks in large hospitals is an emerging challenge. We describe a near fatal outbreak of colistin resistant, carbapenem resistant K. pneumoniae (CRKp) producing metallo beta-lactamases (blaNDM) and blaOXA-48 in the neonatal intensive care unit (NICU) at the background of a larger outbreak involving multiple parts of the hospital and the challenges in its containment. Methods Following identification of an outbreak due to colistin resistant CRKp between April to June 2017 in the NICU, a thorough surveillance of similar cases and the hospital environment was performed to trace the source. All the isolated K. pneumoniae were tested for susceptibility to standard antibiotics by disc diffusion and microbroth dilution methods. Molecular detection of extended spectrum beta lactamases (ESBLs) and carbapenemases (classes A, B, D) genes was done. Enterobacterial repetitive intergenic consensus (ERIC) PCR and multi-locus sequence typing (MLST) was done to determine the genetic relatedness of the isolates. Characteristics of different sequence types were statistically compared (Student’s t-test). Results A total of 45 K. pneumoniae isolates were studied from NICU (14 cases of neonatal sepsis), ICU (18 cases), other wards (7 cases) along with 6 isolates from hospital environment and human colonizers. The primary case was identified in the ICU. All the K. pneumoniae from NICU and 94.4% from the ICU were colistin resistant CRKp. Majority (59.37% and 56.25%) harbored blaSHV/blaCTXM and blaOXA-48 genes, respectively. Two distinct sequence types ST5235 and ST5313 were noted with colistin resistance, distribution within the NICU and mortality as significant attributes of ST5235 (p < 0.05). The outbreak was contained with strengthening of the infection control practices and unintended short duration closure of the hospital. Conclusion Large hospital outbreaks with considerable mortality can be caused by non-dominant clones of colistin resistant CRKp harboring blaOXA-48 and blaNDM carbapenemases in endemic regions. The exact global impact of these sequence types should be further studied to prevent future fatal outbreaks.

Antibiotic Resistance and Molecular Biological Characteristics of Non-13-Valent-Pneumococcal Conjugate Vaccine Serogroup 15 Streptococcus pneumoniae Isolated From Children in China

Background: The isolation rate of serogroup 15 Streptococcus pneumoniae has been increasing since developing countries began administering the 13-valent pneumococcal conjugate vaccine.Methods: We detected the antibiotic resistance and molecular characteristics of 126 serogroup 15 S. pneumoniae strains isolated from children in China. Serotypes were determined via the Quellung reaction. Antibiotic resistance was tested using the E-test or disc diffusion method. Sequence types were assigned via multilocus sequence typing. Data were analyzed using WHONET 5.6 software.Results: The frequencies of S. pneumoniae serotypes 15A, 15B, 15C, and 15F were 29.37, 40.48, 28.57, and 1.59%, respectively. Continuous-monitoring data from Beijing showed that the annual isolation rates of serogroup 15 S. pneumoniae were 7.64, 7.17, 2.58, 4.35, 3.85, 7.41, and 10.53%, respectively, from 2013 to 2019. All 126 serogroup 15 strains were susceptible to vancomycin and ceftriaxone. The non-susceptibility rate to penicillin was 78.57%. All strains were resistant to erythromycin with high minimum inhibitory concentrations (MICs). The multidrug resistance rate was 78.57%. The most common clonal complexes were CC3397, CC6011, CC10088, CC9785, and ST8589.Conclusion: Serogroup 15 S. pneumoniae is common among children in China, and these strains should be continuously monitored.