High-level Gentamicin Resistance Research Articles

Emergence of High-Level Gentamicin Resistance in Streptococcus agalactiae Hypervirulent Serotype IV ST1010 (CC452) Strains by Acquisition of a Novel Integrative and Conjugative Element

Emergence of High-Level Gentamicin Resistance in Streptococcus agalactiae Hypervirulent Serotype IV ST1010 (CC452) Strains by Acquisition of a Novel Integrative and Conjugative Element

Presence of genes encoding aminoglycoside-modifying enzyme (AME) and virulence factors in high-level aminoglycoside-resistant (HLAR) Enterococcus strains isolated from retail chicken meat in Turkey

In this study, the presence of aminoglycoside-modifying enzyme (AME) and virulence factor genes were investigated in previously isolated 32 high-level aminoglycoside-resistant (HLAR) Enterococcus strains isolated from retail chicken meat in Turkey. At least one AME-encoding gene was detected in HLAR enterococci by polymerase chain reaction (PCR). The ant(6ʹ)-Ia was identified as the most prevalent (87.5%, 28/32) AME gene. The aph(3ʹ)-IIIa (78.13%, 25/32), ant(4ʹ)-Ia (68.75%, 22/32), aph(2ʹʹ)-Ib (62.5%, 20/32), aac(6ʹ)-Ie-aph(2ʹʹ)-Ia (21.88%, 7/32) and aph(2ʹʹ)-Ic (9.38%, 3/32) are the other detected AME-encoding genes in strains. The aph(2ʹʹ)-Id was found in none of the HLAR strains. The aph(2ʹʹ)-Ib and ant(6ʹ)-Ia were identified as the most frequently AME-encoding genes in high-level gentamicin-resistant (HLGR) and high-level streptomycin-resistant (HLSR) strains, respectively. Among the 32 HLAR strains, only E. faecalis MSE61.1 and E. avium MSE63.1 were found capable of hydrolyzing gelatine. All HLAR strains showed α-hemolytic activity except E. durans MG13.4 and E. casseliflavus MGM111.1, which were exhibited β- and γ-hemolytic activity, respectively. It was determined that all HLAR strains, except E. durans MGE13.1 and MGE63.1, contain at least one virulence factor gene. The efaAfm (87.5%, 28/32), acm (65.63%, 21/32) and gelE (37.5%, 12/32) were found to be the most prevalent virulence factor genes. HLAR enterococci strains that have the virulence factor genes may pose a risk to consumer health.

Evaluation of antibiotic susceptibility in enterococci isolated from blood culture samples

Aims: Increased vancomycin resistance in enterococci is an important cause of life-threatening bloodstream infections in hospitalized patients. The aim of this study is to determine the antibiotic susceptibility rates of Enterococcus strains isolated from blood cultures in hospitalized patients in Antalya Training and Research Hospital. 
 Methods: The antibiotic resistance rates of Enterococcus strains isolated from blood cultures of patients hospitalized in the service and intensive care units (ICU) between 1 January 2018 and 30 December 2022 were examined retrospectively. Blood samples were studied with the BacT/ALERT 3D culture system (Biomerieux, France). Bacterial identification was performed using conventional methods, Matrix Assisted Laser Desorption-Ionization Time-of-Flight Mass Spectrometer (MALDI-TOF MS) and VITEK 2 (Biomerieux, France) systems. Antimicrobial susceptibility tests were performed with VITEK 2 (Biomerieux, France) systems. Ampicillin, vancomycin, teicoplanin, high-level gentamicin resistance (HLGR) and linezolid susceptibility of isolated strains were evaluated according to the European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. Vancomycin minimal inhibitory concentration (MIC) values of vancomycin resistant strains were studied by microdilution gradient strip test (Bioanalyse).
 Results: A total of 623 strains of enterococci were isolated from blood culture samples. Of the enterococci, 305 (48.9%) were identified as Enterococcus faecalis, 281 (45.6%) Enterococcus faecium, 12 (1.9%) Enterococcus avium, 11 (1.8%) Enterococcus gallinarum, 7 (1.2%) Enterococcus casseliflavus, 2 (0.4%) Enterococcus durans and 1 Enterococcus hirae (0.2%). Ampicillin and HLGR resistance rates of isolated E. faecalis strains were 11 (3.6%) and 72 (23.6%), respectively, and all strains were found to be susceptible to vancomycin, teicoplanin and linezolid. The ampicillin, vancomycin, teicoplanin and HLGR resistance rates of E. faecium strains were determined as 229 (81.5%), 36 (12.8%), 30 (10.7%) and 142 (50.5%), respectively, and all strains were found to be susceptible to linezolid. 
 Conclusion: In infections caused by enterococci, identification and determination of antibiotic susceptibility rates according to culture antibiogram results would be the right approach. Knowing the current susceptibility rates of enterococci isolated from blood culture samples in our hospital will contribute for clinicians' planning of empirical treatment.

The change of antibiotic resistance rates over the years in Enterococcus spp. isolated from clinical specimens

Aims: The aim of this study was to retrospectively evaluate the change in antibiotic resistance rates of Enterococcus species isolated from various clinical samples of outpatients and inpatients in our hospital over the years.
 Methods: Between January 2018 and December 2021, various clinical samples sent to Tekirdağ Namık Kemal University Hospital Microbiology Laboratory from outpatients, inpatients and intensive care patients were retrospectively examined. The samples were inoculated on 5% sheep blood agar, chocolate agar and EMB agar media according to their types and incubated at 37°C. The blood cultures were performed by BACTEC 1280 System (Becton Dickinson, MA, USA). Bacterial identification and antimicrobial sensitivity tests were made using conventional methods and automated systems.
 Results: A total of 417 Enterococcus strains were isolated in our laboratory at four years and included in the study. Of the 417 isolates, 204 (48.9%) were isolated from male patients and 213 (51.1%) from female patients. The mean age of the patients was 57.79±22.9 years (0-96 years). It was determined that 36.9% of the isolates belonged to outpatients, 33.4% to inpatients and 29.7% to intensive care unit patients. Of the 122 enterococci isolates identified as species, 49.2% were typed as Enterococcus faecalis (E. faecalis) and 40.2% as Enterococcus faecium (E. faecium). Of the 417 isolates, 60.4% were isolated from urine samples, 24.2% from blood samples, and 8.9% from wound samples. Considering the total antibiotic resistance rates; ampicillin was 34.9%, ciprofloxacin was 46.4%, vancomycin was 8.4%, tigecline was 3.2%, high-level gentamicin was 49.0%. Linezolid and nitrofurantoin resistance were not detected. Ampicillin and vancomycin resistance rates were determined to have a statistically significant increase within four years. Ampicillin, ciprofloxacin, vancomycin and high-level gentamicin resistance rates were found to be significantly higher in isolates obtained from inpatients and intensive care patients compared to enterococcal isolates obtained from outpatients.
 Conclusion: In our study, it was determined that antibiotic resistance in enterococcal isolates, which are the causative agents of infection in our hospital, increased over the years. In this way, determining the change in antibiotic resistance rates is beneficial in determining appropriate antibiotic use policies. It is thought that conducting surveillance studies on antibiotic resistance periodically and taking new measures according to changing antibiotic resistance rates will be beneficial in terms of treatment.

Antibiotic resistance and virulence potentials of E. faecalis and E. faecium in hospital wastewater: a case study in Ardabil, Iran.

Hospital wastewater can contaminate the environment with antibiotic-resistant and virulent bacteria. We analyzed wastewater samples from four hospitals in Ardabil province, Iran for Enterococcus faecium and Enterococcus faecalis using culture and molecular methods. We also performed antimicrobial susceptibility testing and polymerase chain reaction testing for resistance and virulence genes. Out of 141 enterococci isolates, 68.8% were E. faecium and 23.4% were E. faecalis. Ciprofloxacin and rifampicin showed the highest level of resistance against E. faecalis and E. faecium isolates at 65%. High-level gentamicin resistance (HLGR), high-level streptomycin resistance (HLSR), ampicillin, and vancomycin resistance were observed in 25, 5, 10, and 5.15% of E. faecium, and 15, 6, 15, and 3.03% of E. faecalis isolates, respectively. The ant(6')-Ia and ant(3')-Ia genes that were responsible for streptomycin resistance were observed in HLSR isolates and aph(3')-IIIa and aac(6') Ie-aph(2″)-Ia genes accounting for gentamicin resistance were detected in HLGR isolates. vanA was the predominant gene detected in vancomycin-resistant isolates. The majority of isolates were positive for gelE, asa1, esp, cylA, and hyl virulence genes. We found that drug-resistant and virulent E. faecalis and E. faecium isolates were prevalent in hospital wastewater. Proper treatment strategies are required to prevent their dissemination into the environment.

High-level in vitro resistance to gentamicin acquired in a stepwise manner in Neisseria gonorrhoeae.

Gentamicin is used in several alternative treatments for gonorrhoea. Verified clinical Neisseria gonorrhoeae isolates with gentamicin resistance are mainly lacking and understanding the mechanisms for gonococcal gentamicin resistance is imperative. We selected gentamicin resistance in gonococci in vitro, identified the novel gentamicin-resistance mutations, and examined the biofitness of a high-level gentamicin-resistant mutant. Low- and high-level gentamicin resistance was selected in WHO X (gentamicin MIC = 4 mg/L) on gentamicin-gradient agar plates. Selected mutants were whole-genome sequenced. Potential gentamicin-resistance fusA mutations were transformed into WT strains to verify their impact on gentamicin MICs. The biofitness of high-level gentamicin-resistant mutants was examined using a competitive assay in a hollow-fibre infection model. WHO X mutants with gentamicin MICs of up to 128 mg/L were selected. Primarily selected fusA mutations were further investigated, and fusAR635L and fusAM520I + R635L were particularly interesting. Different mutations in fusA and ubiM were found in low-level gentamicin-resistant mutants, while fusAM520I was associated with high-level gentamicin resistance. Protein structure predictions showed that fusAM520I is located in domain IV of the elongation factor-G (EF-G). The high-level gentamicin-resistant WHO X mutant was outcompeted by the gentamicin-susceptible WHO X parental strain, suggesting lower biofitness. We describe the first high-level gentamicin-resistant gonococcal isolate (MIC = 128 mg/L), which was selected in vitro through experimental evolution. The most substantial increases of the gentamicin MICs were caused by mutations in fusA (G1560A and G1904T encoding EF-G M520I and R635L, respectively) and ubiM (D186N). The high-level gentamicin-resistant N. gonorrhoeae mutant showed impaired biofitness.

Prevalence and antimicrobial susceptibility of high-level gentamicin resistant enterococci isolated from urine at a hospital in Pune, India

Introduction: Enterococci are one of the common organisms isolated from hospitalized patients with urinary tract infections. Guidelines recommend testing enterococcifor susceptibility to high-level gentamicin (HLG) and streptomycin. The present study was planned to determine the susceptibility of uropathogenic enterococci to high-level gentamicin in a tertiary care hospital. Materials and Methods: Prospective observational research was carried out at a tertiary care hospital for two years on all isolated enterococci from urine specimens. Identification and antibiotic susceptibility were performed as per standard methods. All the isolated enterococci were tested for high level gentamicin ((120µg) resistance and susceptibility to other recommended antimicrobial agents by standard methods. Results: A total of 320 uropathogenic enterococci were isolated and tested for antibiotic susceptibility. The majority of enterococci were isolated from elderly (34.06%) and admitted patients (69.06%). A total of 68.4% isolated enterococci were HLG resistant. HLG resistant enterococci were highly resistant to erythromycin (96.3%), ciprofloxacin (96.8%) and nalidixic acid (97.7%). Enterococci sensitive to HLG were significantly (p <0.05) less resistant to the other antimicrobial agents except nalidixic acid. Only 20.5% isolated Enterococci were resistant to vancomycin. All isolated enterococci were susceptible to linezolid. Conclusion: The study demonstrated high prevalence of HLG resistant enterococci causing UTI in our hospital setting. Compared to HLG sensitive enterococci, HLG resistant enterococci were more resistant to other antimicrobial agents tested. The findings highlight the need for mandatory testing of enterococci for HLG resistance to determine effective antimicrobials for treatment. IMC J Med Sci. 2023; 17(2):008. DOI: https://doi.org/10.55010/imcjms.17.018 *Correspondence: Dr. Sahjid Mukhida, Department of Microbiology, Dr. D. Y. Patil Medical College, Hospital and Research Centre, Dr. D. Y. Patil Vidyapeeth, Pimpri, Pune, Maharashtra, India. E-mail: drssmukhida@rediffmail.com

Prevalence of Genes Encoding Resistance to Aminoglycosides and Virulence Factors Among Intestinal Vancomycin-Resistant Enterococci

Background: Vancomycin-resistant enterococci (VRE) are recognized as nosocomial pathogens with increased importance in recent years. These bacteria are frequently isolated from patients admitted to intensive care units (ICUs). Enterococcal pathogenicity is enhanced by different antibiotic resistance and virulence determinants. Objectives: The present study aimed to assess the prevalence of genes encoding resistance to antibiotics and virulence factors in intestinal VRE isolates from ICU patients. Methods: In this study, 23 VREs were investigated. Minimum inhibitory concentrations (MICs) to nine antimicrobial agents were examined using E-test. Genes encoding vancomycin resistance (vanABCDMN), aminoglycoside-modifying enzymes (aac(6')-Ie-aph(2")-Ia, aph(2")-Ib, aph(2")-Ic, aph(2")-Id, aph(3')-IIIa, ant(3')-Ia, ant(4')-Ia, ant(6')-Ia), together with genes for various virulence factor (ace/acm, asa1, cylA, efaA, esp, gelE and hyl), were detected using multiplex PCR. Results: The species distribution of the tested VRE was as follows: Nine Enterococcus casseliflavus, seven E. gallinarum, and seven E. faecium. The vanA gene was found in all E. faecium, in six of which the classical VanA phenotype was observed. The vancomycin (vanC) phenotype was associated with the presence of vanC1 gene in E. gallinarum and the vanC2 gene in E. casseliflavus isolates. The aac(6')-Ie-aph(2")-Ia gene was encoding high-level gentamicin resistance (HLGR) in the studied VRE. All E. faecium were positive for acm and esp, while acm in combination with esp or hyl was detected in 2 vanC enterococci. Conclusions: According to the findings, there was a correlation between the phenotype and the genotype of glycopeptide resistance in the tested VRE. HLGR was more prevalent in E. faecium because of the presence of aac(6')-Ie-aph(2")-Ia. The higher prevalence of virulence determinants was confirmed in vanA isolates compared to the studied vanC-carrying enterococci.

Species prevalence, antimicrobial susceptibility and detection of virulence factors of enterococci isolated from tertiary care hospital

Introduction: Emergence of multidrug resistant nosocomial enterococcus strains emphasizes the need for further investigating enterococci. Objectives: To characterize enterococci from various clinical specimens, to determine the antimicrobial susceptibility pattern and to explore the association between virulence factors and antimicrobial resistance. Material and Methods: Two hundred and eighty three clinical isolates of enterococcus were speciated and subjected to antimicrobial susceptibility testing using Kirby Bauer disc diffusion method. They were screened for vancomycin resistance by vancomycin screening agar method as recommended by Clinical Laboratory Standards Institute 2014, and confirmed by determination of minimum inhibitory concentration using agar dilution and E test. Genotypic confirmation was done by polymerase chain reaction. Virulence factors (haemolysin, gelatinase and biofilm production) were detected phenotypically. Results: Of the 283 enterococci isolated, 12 species were identified; predominant species was Enterococcus faecalis (82.33%). High level gentamicin resistance (HLGR) and vancomycin resistance were observed among 55.57% and 6.01% of Enterococcus isolates respectively. All vancomycin resistant enterococci (VRE) were Enterococcus faecalis and had vanA phenotype and genotype. Sensitivity to linezolid was 100 per cent among enterococci. Hemolysin, gelatinase and biofilm production were seen in 15.90%, 12.36% and 13.43% of enterococcal isolates respectively.

Species prevalence, antimicrobial susceptibility of enterococci isolated from various clinical samples in tertiary care hospital

Introduction: Emergence of multidrug resistant nosocomial enterococcus strains emphasizes the need for further investigating enterococci. Objectives: To characterize enterococci from various clinical specimens, to determine the antimicrobial susceptibility pattern and to explore the association between virulence factors and antimicrobial resistance. Material and Methods: Two hundred and eighty three clinical isolates of enterococcus were speciated and subjected to antimicrobial susceptibility testing using Kirby Bauer disc diffusion method. They were screened for vancomycin resistance by vancomycin screening agar method as recommended by Clinical Laboratory Standards Institute 2020, and confirmed by determination of minimum inhibitory concentration using agar dilution and E test. Genotypic confirmation was done by polymerase chain reaction. Results: Of the 283 enterococci isolated, 12 species were identified; predominant species was Enterococcus faecalis (82.33%). High level gentamicin resistance (HLGR) and vancomycin resistance were observed among 55.57% and 6.01% of Enterococcus isolates respectively. All vancomycin resistant enterococci (VRE) were Enterococcus faecalis and had vanA phenotype and genotype. Sensitivity to linezolid was 100 per cent among enterococci. Conclusion: Our study reveals the occurrence of sizable number of HLGR isolates and emergence of VRE.

Pediatric Enterococcal Bacteremia: A 12-Year Retrospective Study in a French Pediatric Center.

Enterococcal bloodstream infections (EBSIs) are rare infections in children associated with 5%-10% of mortality in previous studies. The recent evolution of antimicrobial resistance and therapies require updated data. We conducted an observational retrospective study between January 2008 and December 2019 describing the characteristics of children with EBSI in a French pediatric hospital. All positive Enterococcus spp. blood cultures associated with sepsis symptoms were analyzed. We also compared characteristics of healthcare-associated infections (HAIs) and community-acquired infections (CAIs) and described antimicrobial resistance evolution during this period. In total 74 EBSI were included. Enterococcus faecalis was the most common pathogen (n = 60/74, 81%) followed by Enterococcus faecium (n = 18, 24%), including 4 enterococcal coinfections. EBSIs were mainly associated with central-line associated infection (38%), surgical site infection (14%) or urinary tract infection (11%). An underlying disease was present in 95.9%. However, 4 patients died in the month following the EBSI resulting in a 5.4%, 30-day mortality. All were HAI. HAI (84% of EBSI) was associated with longer bacteremia [31% persistent bacteremia (more than 3 days) versus 0% for CAI; P = 0.029] and more antimicrobial resistance. Amoxicillin resistance is increasing since 2013 in E. faecium (63% in 2013-2019), although high-level gentamicin resistance is stable (19%). Only 1 EBSI due to vancomycin-resistant Enterococcus was described in our cohort, who died. EBSIs are rare infections in children mostly described in children with underlying disease. Healthcare-associated bacteremia is associated with higher rates of resistance and poorer prognosis, requiring the involvement of pediatric infectious disease specialists to improve management.

Prevalence and antimicrobial susceptibility of Enterococcus spp. from urine of dogs and cats in northwestern Croatia

This study investigated the prevalence and antimicrobial susceptibility of enterococci isolated from dogs and cats with urinary tract infections in northwestern Croatia. During this study, the laboratory received 787 urine samples, 651 from dogs and 136 from cats. A total of 260 urine samples (211 from dogs and 49 from cats) were bacteriologically positive. Of these, 29 isolates belonged to Enterococcus spp.; 22 from dogs and seven from cats. Enterococci isolates were identified by PCR method, 12 of which were Enterococcus faecium and 17 were Enterococcus faecalis species. In dogs, 16 E. faecalis and six E. faecium strains were identified, whereas in cats, six E. faecium and only one E. faecalis strain were identified. Antimicrobial susceptibility was determined by the Kirby-Bauer disk diffusion method for nine antimicrobials: penicillin, ampicillin, vancomycin, nitrofurantoin, rifampicin, tetracycline, chloramphenicol, enrofloxacin, ciprofloxacin. The isolates were tested for high-level resistance to streptomycin and gentamicin. The highest resistance of Enterococcus spp. was observed to rifampicin (86%) and enrofloxacin (83%), followed by tetracycline and ciprofloxacin (69%). Resistance to vancomycin was 28%, and the lowest resistance was to chloramphenicol (17%). Multidrug resistance was found in 76% of enterococci isolates. High-level streptomycin resistance was detected in 17% and high-level gentamicin resistance in 10% of the isolated enterococci. When comparing species susceptibility, E. faecium isolates were significantly more resistant to penicillin, ampicillin, nitrofurantoin, and ciprofloxacin (p < 0.05). Eleven E. faecium isolates (92%) and 12 E. faecalis isolates (76%) were multidrug resistant.

Genomic Traits Associated with Virulence and Antimicrobial Resistance of Invasive Group B Streptococcus Isolates with Reduced Penicillin Susceptibility from Elderly Adults.

ABSTRACTThis study aimed to investigate genomic traits underlying the antimicrobial resistance and virulence of multidrug-resistant (MDR) group B streptococci with reduced penicillin susceptibility (PRGBS) recovered from elderly patients with bloodstream infections, which remain poorly characterized. The pangenome was found to be open, with the predicted pan- and core genome sizes being 3,531 and 1,694 genes, respectively. Accessory and unique genes were enriched for the Clusters of Orthologous Groups (COG) categories L, Replication, recombination, and repair, and K, Transcription. All MDR PRGBS isolates retained a core virulence gene repertoire (bibA, fbsA/-B/-C, cspA, cfb, hylB, scpB, lmb, and the cyl operon), supporting an invasive ability similar to that of the other invasive GBS, penicillin-susceptible GBS (PSGBS), and noninvasive PRGBS isolates. The putative sequence type 1 (ST1)-specific AlpST-1 virulence gene was also retained among the serotype Ia/ST1 PRGBS isolates. In addition to tet(M) and erm(B), mef(A)-msr(D) elements or the high-level gentamicin resistance gene aac(6′)-aph(2″), which are both rare in PSGBS, were detected among those MDR PRGBS isolates. In the core single-nucleotide polymorphism (SNP) phylogenetic tree, all invasive ST1 PRGBS isolates with serotypes Ia and III were placed together in a clade with a recombination rate of 3.97, which was 36 times higher than the value found for a clade formed by serotype V/ST1 PSGBS isolates derived mostly from human blood. ST1 has been the predominant sequence type among the PRGBS isolates in Japan, and serotypes Ia and III have been very rare among the ST1 PSGBS isolates. Thus, these lineages that mostly consisted of serotypes Ia/ST1 and III/ST1 PRGBS could possibly emerge through recombination within the ST1 populations.IMPORTANCE Streptococcus agalactiae, or group B Streptococcus (GBS), is recognized as the leading cause of neonatal invasive infections. However, an increasing incidence of invasive GBS infections among nonpregnant adults, particularly the elderly and those with underlying diseases, has been observed. There is a trend toward the increasing occurrence of penicillin nonsusceptibility among GBS clinical isolates, from 4.8% in 2008 to 5.8% in 2020 in Japan. Also, in the United States, the frequency of adult invasive GBS isolates suggestive of β-lactam nonsusceptibility increased from 0.7% in 2015 to 1.0% in 2016. In adults, mortality has been significantly higher among patients with bacteremia than among those without bacteremia. Our study revealed that invasive GBS with reduced penicillin susceptibility (PRGBS) isolates harbor major virulence and resistance genes known among GBS, highlighting the need for large population-based genomic surveillance studies to better understand the clinical relevance of invasive PRGBS isolates.

Prevalence of High Level Gentamicin Resistance among the Clinical Isolates of Enterococci Species

Enterococci infections, have drawn attention of clinicians due to rapid increase in high level aminoglycoside resistance (HLAR). This resistance predicts failure of β-lactam antibiotic and aminoglycoside combination, which is the current treatment of choice for serious enterococci infections. This led us to investigate about the prevalence of HLAR enterococci in our hospital setting in Shimoga, Karnataka. All the clinical samples received at Microbiology laboratory, McGan hospital, Shivamogga between June 2016 and December 2016 was considered for the study. Enterococci were identified and further speciated by following conventional method. Antibiotic susceptibility pattern of all the isolates was determined according to CLSI guidelines. High level gentamicin resistance was detected by disc diffusion method using 120µg gentamicin disc. A total of 64 Enterococci species were isolated from the clinical specimens. On speciation, Enterococcus faecalis (E. faecalis) accounted for 72% (46) of the total isolates, 24%(16) of the isolates were Enterococcus faecium (E. faecium)and 4% (2) isolates were Enterococcus durans (E. durans). High level gentamicin resistance was noted in 42% (27) among the total isolates. E. faecium was found to be more resistant compared to E. faecalis. E. durans was a sensitive strain. Our study reconfirms the high prevalence of HLAR in the clinical setting. The study stresses on the need for regular screening of HLAR in all Enterococci infections and revise the battery of drugs for its treatment according to the report.

Laboratory breakpoints for assessing high level gentamicin resistance in Streptococcus agalactiae: it is the time for a consensus

Group B streptococcus (GBS, Streptococcus agalactiae) is the most frequent cause of meningitis and a notable cause of sepsis in the first 3 months of life [1]. In adults, GBS is an occasional pathogen, mostly associated with genitourinary infection, but it can also cause invasive infections in those with certain predisposing conditions, particularly advanced age, diabetes, cancer, HIV, and liver disease [2].

Molecular Characterization of High-Level Aminoglycoside Resistance among Enterococcus Species.

Background Enterococci are nosocomial pathogen. They can develop high-level resistance to aminoglycoside by producing aminoglycoside modifying enzymes (AMEs). In enterococci, high level resistance to aminoglycosides is mediated by acquisition of plasmid mediated genes encoding for aminoglycoside modifying enzymes (AMEs). High level gentamicin resistance (MIC ≥ 500μg /mL) is predominantly mediated by aac(6′)-Ie-aph(2″)-Ia, encoding the bifunctional aminoglycoside modifying enzyme AAC(6′)-APH(2″). This enzyme eliminates the synergistic activity of gentamicin when combined with a cell wall active agent. Other AME genes such as aph(2″)-Ib, aph(2″)-Ic, aph(2″)-Id and ant(4′)-1a have also been detected in enterococci. Objective This study was carried out to determine the diverse prevalence of AME and their pattern of occurrence in the clinical isolates of Enterococci . Materials and Methods A total number of 150 clinical isolates were included in this study. Susceptibility to various antibiotics was determined by disc diffusion. Minimum Inhibitory Concentration (MIC) was ascertained by agar dilution method. Polymerase chain reaction was done to screen the following AMEs (aac(6′)-Ie-aph(2″)-Ia; aph(2″)-Ib; aph(2″)-Ic; aph(2″)-Id and aph(3′)- IIIa genes) . Results 51.3% of the study isolates exhibited high level gentamicin resistance. Polymerase chain reaction revealed that aph(3′)-111a is the most prevalent AME, followed by aac(6′)-1e-aph(2″)-1a . The combination of both the genes were detected in 44.1% of the study isolates. The rest of the AMEs and their combinations were not encountered in this study. 8.6% of the study isolates did not harbour any AME genes screened for, but was phenotypically resistant to gentamicin. In contrast 31.3% anchored the AME genes but phenotypically appeared susceptible to gentamicin. Conclusion This study indicates the high- level aminoglycoside resistance disseminated among Enterococci in our geographical region. It also emphasizes the detection of AMEs by PCR is mandatory because strains that appear susceptible by disc diffusion and/or MIC method may harbour one or more AMEs genes leading to therapeutic failure.

High-level gentamicin resistance mediated by Aac(6')-Ie-aph(2")-Ia gene in Enterococcus species isolated from clinical samples in Northern India.

CONTEXT:Enterococci are known to cause life-threatening infections which are difficult to treat as the organism harbors innate resistance to many antibiotics and can amass resistance toward many others through plasmid-mediated genetic exchange.AIMS:The study evaluates the drug susceptibility profile of various Enterococcus species isolated from various patient specimens submitted for bacteriological analysis and check the incidence of aac(6′) Ie-aph(2”) Ia gene.SETTING AND DESIGN:This in vitro cross-sectional study was executed at bacteriology laboratory of a 470 bedded hospital in New Delhi.MATERIALS AND METHODS:Drug susceptibility testing was carried out on enterococcal isolates. High-level gentamicin-resistant (HLGR) isolates detected by micro broth dilution assay were then subjected to molecular detection of aac(6′) Ie-aph(2”) Ia gene.STATISTICAL ANALYSIS USED:The level of significance was established by Chi-square test.RESULTS:Among the 182 enterococcal stains detected, 76.9% were Enterococcus faecalis and 20.3% were Enterococcus faecium. 12.08% strains were vancomycin resistant. 39% expressed resistance toward high-level gentamicin (HLG) and this finding was significantly higher in E. faecium than E. faecalis. HLGR strains expressed a higher degree of resistance to other drugs in contrast to non-HLGR isolates. In 67 out of 71 HLGR isolates the bifunctional gene was detected.CONCLUSION:Considerable presence of HLG and vancomycin resistance in the clinical isolates is alarming and should be taken seriously. The study shows high dissemination of aac(6′)-Ie-aph(2”)-Ia gene among Enterococci isolated from the region.

High-Level Resistance to Aminoglycosides Among Multidrug Resistant Non-faecalis and Non-faecium Enterococci.

Enterococci are considered as important causative pathogens of a variety of community and hospital-acquired infections. Due to the development of multidrug resistant (MDR) enterococci and the emergence of strains possessing high-level resistance to antimicrobial agents, treatment of their infections has been more complicated. In addition to more prevalent species of the Enterococcus genus, non-faecalis/non-faecium species are also responsible for severe healthcare-associated infections. Therefore, this study was designed to investigate high-level gentamicin resistance among the clinical isolates of non-faecalis and non-faecium enterococci in Shiraz, in the southwest of Iran. A total of 28 non-faecalis/non-faecium spp. were isolated from various infections. They were identified by the conventional methods. Antimicrobial resistance patterns, multidrug resistance, and high-level gentamicin resistance were determined, according to CLSI guidelines and related definitions. Detection of aminoglycoside resistance genes was also performed using standard procedures. All of the isolates were MDR (100%), and 75% of them were high-level gentamicin resistant (HLGR) (MIC ≥ 500 μg/mL). The distributions of aac(6')-Ie-aph(2'')-Ia and aph(3')-IIIa resistance genes were 82.1% and 75%, respectively. The aph(2")-Ib, aph(2")-Ic, aph(2")-Id, and ant(4')-Ia genes were not found in any isolate. Although vancomycin resistance was observed in 19 (67.8%) isolates, all of the isolates were susceptible to linezolid and fosfomycin. Our data indicate a high rate of MDR non-faecalis/non-faecium isolates. Furthermore, high-level gentamicin resistance was notable and all of the HLGR isolates harbored at least one of aac(6')-Ie-aph(2'')-Ia or aph(3')-IIIa resistance gene.

Analysis of the phenotypic and genotypic antimicrobial resistance profiles of clinically significant enterococci isolated in the Provincial Specialist Hospital in Lublin, Poland

Abstract The increasing significance of enterococci as healthcare-associated pathogens can be linked to their limited susceptibility to antibiotics. In this study, phenotypic and genotypic resistance profiles of 35 [n=18 E. faecium (Efm); n=17 E. faecalis (Efs)] invasive isolates cultured from hospitalized patients were analysed. Phenotypic identification was verified by the multiplex PCR targeting the 16S rDNA and the ddl genes encoding for the Efs and Efm – specific ligases. Antimicrobial susceptibility was determined using the disc diffusion method and E-tests. The high-level streptomycin resistance (HLSR), high-level gentamicin resistance (HLGR) and glycopeptide resistance was verified by amplification of the ant(6)-Ia, aac(6’)-Ie-aph(2’’)-Ia, as well as vanA and vanB genes, respectively. More than 70% of all isolates were cultured from patients in the Intensive Care and Internal Medicine Units. Blood was the predominant (77%) site of isolation. All Efm isolates were resistant to ampicillin, imipenem, and norfloxacin; 17 isolates demonstrated high-level aminoglycoside resistance (HLAR), including 27.7% with HLSR, 38.8% with HLGR and 27.7% with both phenotypes. HLAR was also common in Efs (HLSR&gt;70%, HLGR&gt;50%), followed by norfloxacin (64.7%) and ampicillin (11.7%) resistance. The ant(6)-Ia and aac(6’)-Ie-aph(2’’)-Ia genes were detected in &gt;90% of the HLSR and HLGR isolates, respectively. Glycopeptide resistance was detected in 4 (22.2%) Efm isolates and mediated by the vanA gene. 19 (54.3%) isolates were multidrug resistant, including 17 (89.5%) Efm. All isolates were susceptible to linezolid. The study constitutes a contribution to the analysis of enterococcal antimicrobial resistance in Polish hospitals. The monitoring of enterococcal prevalence and antimicrobial resistance is crucial to control and prevent infections.

Antibiotic resistance of Enterococcus species: 3-year data

Aim: The aim of this study is to investigate the prevalence of Enterococcus species and to evaluate susceptibilities to antimicrobial agents in a state (secondary) hospital.&#x0D; Material and Methods: A total of 1676 enterococci strains (490 E.faecium, 1146 E.faecalis, 10 E.casseliflavus/E.gallinarum and 30 other Enterococcus species) isolated from cultures obtained from January 2017 to December 2019 in XXX Hospital were included. Blood cultures were incubated in automated device (Render Biotech Co.Ltd., PRC). Other cultures were incubated with conventional methods. Grown colonies were identified by PhoenixTM 100 automated system (Becton Dickinson, USA). Identifications that need confirmation or strains identified to genus level were further evaluated with conventional techniques. Antimicrobial susceptibility testing were performed by same system, Kirby-Bauer disc diffusion and gradient strip method according to EUCAST guidelines.&#x0D; Results: 43.1%, 27.1%, 14.7% and 15.1% of enterococci were isolated from urine, blood/sterile body fluids, wound/abscess and other samples. Majority of the strains were ciprofloxacin (72.0%) and levofloxacin (74.1%) resistant, and more than 40% showed ampicillin and high-level gentamicin resistance. Glycopeptide resistance was relatively high (5.4%), especially when considering E.faecium (12.1%). There was not any tigecycline and linezolid resistance. &#x0D; Conclusions: Antimicrobial resistance is a serious and growing public health problem affecting all countries, which is not just a topic of medicine, but multiple sectors such as commercial companies, food industry, veterinarians, etc. High percentages of resistance strongly indicate to get a local action, which should be followed by national and global one.