Clindamycin Resistance Research Articles

Molecular Characteristics of Staphylococcus aureus Strains to Carry Panton-Valentine Leukocidin Genes Isolated from Hospitalized Patients in Tehran, Iran

Background: Staphylococcus aureus with concurrent resistance to antibacterial agents is emerging globally. This emergence might be due to the production of different virulence determinants, notably Panton-Valentine leukocidin (PVL). Objectives: This study aimed to investigate the genetic characteristics of PVL-positive S. aureus strains isolates from clinical samples. Methods: An epidemiological study was conducted on 65 S. aureus isolates carrying pvl genes. An antibiogram test by the disk diffusion and broth microdilution methods was conducted to assess antimicrobial resistance profiles. Results: All detected methicillin-resistant S. aureus (MRSA) isolates were confirmed by mecA polymerase chain reaction (PCR) assays. The PVL-positive isolates were characterized using multiplex PCR assay to detect staphylococcal cassette chromosome mec (SCCmec) and agr types. The PVL frequency was 19.5% and 17.6% in MRSA and methicillin-susceptible S. aureus (MSSA), respectively. Among the PVL-positive isolates, 66.2% and 33.8% were MRSA and MSSA, respectively. Multidrug resistance amounted to 84.6% of the isolates (MRSA: 61.5%, MSSA: 23.1%). Staphylococcal cassette chromosome mec III was dominated (55.8%; 24/43). The most commonly identified agr was type III (53.8%; 35/65). Resistance to vancomycin amounted to 12.3% of the isolates, and all belonged to agr type III and SCCmec type III. The frequency of inducible and constitutive clindamycin resistance among PVL-positive MRSA strains (12.3% and 26.1%) was higher than PVL-positive MSSA strains (7.7% and 15.4%). Most constitutive and inducible clindamycin resistance isolates belonged to agr type III (26.2% and 18.5%) and SCCmec type III (each 27.9%). In the present study, 32.3% of the isolates were confirmed as mupirocin resistant, and all were MRSA, 9 (42.9%) and 12 (57.1%) isolates of which exhibited high-level mupirocin resistant (HLMUPR) and low-level mupirocin resistant phenotypes. All HLMUPR MRSA isolates belonged to SCCmec III and recovered from wound samples. Conclusions: The emergence of vancomycin-resistant S. aureus strains among PVL-positive S. aureus strains in Iran is a serious alarm and seems to be becoming the greatest concern in the treatment of staphylococcal infections in the healthcare setting. The present study reinforces plausible direct transfers between community and nosocomial PVL-positive S. aureus types.

Superbugs and Bacterial Epidemiology from Wound Infection at Health Institutions in Northeast Ethiopia.

Wound infection plays an important role in the development of chronicity by delaying wound healing, prolonging hospital stay, increasing treatment cost and is responsible for significant morbidity. The aim of this study was to investigate the bacterial epidemiology, multi-drug resistance, and associated risk factors for wound infection at health institutions in Northeast Ethiopia. A facility-based cross-sectional study was conducted from February to April 2021. Demographic, clinical, and risk factor variables were collected using a structured questionnaire. Swabs/pus from wound were collected using sterile applicator swab. Specimens were inoculated on culture media and bacterial isolates were identified using microbiological techniques. Antimicrobial susceptibility test was performed using Kirby-Bauer disc diffusion method. Statistical analysis was done using SPSS software. A total of 229 participants were included in this study. A total of 170 bacterial isolates (74.2%) were isolated. The predominant isolates were S. aureus 80 (47.05%), followed by P. aeruginosa 29 (17.05%), E. coli 22 (12.94%), and Klebsiella spp. 16 (9.41%). Tetracycline (71.7%), clindamycin (15.2%), erythromycin (30.4%), penicillin (80.4%), and co-trimoxazole (80.4%) resistance rates were observed among Gram positive bacterial isolates. The overall prevalence of multi-drug resistance was 71%. Hence, improving the laboratory setup for culture and drug susceptibility testing is recommended for effective treatment of wound infection and to improve infection prevention and control practices in healthcare settings.

Microbiology and Antibiotic Resistance Profiles of Orbital Subperiosteal Abscesses: A Comparison of Pediatric, Adolescent, and Adult Populations.

The purpose of this study was to compare the microbiology and antibiotic resistance profiles of orbital subperiosteal abscesses (SPA) among 3 age cohorts. A retrospective study was conducted at a tertiary care center through a medical record search to identify patients with orbital cellulitis and SPA on imaging from January 1, 2000 to September 10, 2022. Patients were categorized into pediatric (<9 years old), adolescent (9-18 years old), and adult (>18 years old) cohorts. Primary outcomes included culture and antibiotic susceptibility results. Secondary outcomes included antibiotic therapy and surgical intervention. Of the 153 SPA patients included, 62 (40.5%) were in the pediatric cohort (4 months-8 years, mean 5.0 ± 2.7), 51 (33.3%) were adolescent (9-18 years, 12.7 ± 2.8), and 40 (26.1%) were adult (19-95, 51.8 ± 19.3). Viridians group Streptococci were the most frequent organisms isolated across groups. The anaerobic infection rate was higher in the adult compared to the pediatric group (23.0% vs, 4.0%, p = 0.017), while that of the adolescent did not differ significantly from either. Pediatric patients carried a lower rate of clindamycin resistance than adolescent and adult cohorts, who shared similar rates (0 vs. 27.0% and 28.0%, respectively; p = 0.016). There were progressive increases in duration of intravenous antibiotic therapy ( p < 0.195) and rate of surgical intervention ( p < 0.001) going from younger to older cohorts. Organisms isolated from orbital SPA from the past 2 decades demonstrate a predominance of Streptococcal species. Older age may be associated with anaerobic infection, clindamycin resistance, and more aggressive management. Adolescent infections are more similar to adult rather than pediatric counterparts but may require less aggressive management than the former.

Understanding antimicrobial susceptibility profile of Finegoldia magna: an insight to an untrodden path

BackgroundFinegoldia magna (formerly known as Peptococcus magnus or Peptostreptococcus magnus) belonging to phylum Firmicutes, class Clostridia and genus Finegoldia, is the only species known to cause infections in human beings. Amongst Gram positive anaerobic cocci, F. magna is known to be the most virulent with a high pathogenic potential. Significant upsurge in antimicrobial resistance among anaerobes has been documented by various studies. F. magna is known to be susceptible to most of the anti-anaerobic antimicrobials, however, multidrug resistant strains are being reported in literature. The present study was undertaken to highlight the role of F. magna in clinical infections and to analyze their antimicrobial susceptibility patterns.MethodsThe present study was conducted in a tertiary care teaching hospital in Southern India. 42 clinical isolates of F. magna recovered from diverse clinical infections between January 2011 to December 2015 were studied. These isolates were subjected to antimicrobial susceptibility testing against metronidazole, clindamycin, cefoxitin, penicillin, chloramphenicol and linezolid.ResultsAmong the 42 isolates studied, majority of them were revived from diabetic foot infections (31%) followed by necrotizing fasciitis (19%) and deep-seated abscesses (19%). All the F. magna isolates showed good in-vitro activity against metronidazole, cefoxitin, linezolid and chloramphenicol. Clindamycin and penicillin resistance were observed against 9.5% and 2.4% of the isolates respectively. However, β-lactamase activity was not detected.ConclusionThe antimicrobial resistance among anaerobes varies from pathogen to pathogen and region to region. Hence, a deep understanding of resistance pattern is necessary for better management of clinical infections.

Genomic characterization of emerging invasive Streptococcus agalactiae serotype VIII in Alberta, Canada

Invasive Group B Streptococcus (GBS) can infect pregnant women, neonates, and older adults. Invasive GBS serotype VIII is infrequent in Alberta; however, cases have increased in recent years. Here, genomic analysis was used to characterize fourteen adult invasive serotype VIII isolates from 2009 to 2021. Trends in descriptive clinical data and antimicrobial susceptibility results were evaluated for invasive serotype VIII isolates from Alberta. Isolate genomes were sequenced and subjected to molecular sequence typing, virulence and antimicrobial resistance gene identification, phylogenetic analysis, and pangenome determination. Multilocus sequencing typing identified eight ST42 (Clonal Complex; CC19), four ST1 (CC1), and two ST2 (CC1) profiles. Isolates were susceptible to penicillin, erythromycin, chloramphenicol, and clindamycin, apart from one isolate that displayed erythromycin and inducible clindamycin resistance. All isolates carried genes for peptide antibiotic resistance, three isolates for tetracycline resistance, and one for macrolide, lincosamide, and streptogramin resistance. All genomes carried targets currently being considered for protein-based vaccines (e.g., pili and/or Alpha family proteins). Overall, invasive GBS serotype VIII is emerging in Alberta, primarily due to ST42. Characterization and continued surveillance of serotype VIII will be important for outbreak prevention, informing vaccine development, and contributing to our understanding of the global epidemiology of this rare serotype.

Epidemiological Aspects and Antibiotics Susceptibility Patterns of Streptococcus pyogenes Isolated from Subjects with Tonsillitis, Sudan

Background: Globally, Streptococcus pharyngitis is a major public health challenge. The current study investigates the prevalence of Streptococcal pyogenes among children under 17 years old in ENT Kosti Teaching Hospital and examines the susceptibility of isolated S. pyogenes strains to commonly used antibiotics.Methods: A total of 384 throat swabs were obtained from children under the age of 17 who attended the Kosti Teaching Hospital between 2019 and 2021. Streptococcus pyogenes was isolated by conventional microbiology procedures. Each S. pyogenes strain was subjected to antibiotic susceptibility testing according to the CLSI guidelines.Results: Most participants of this study were females 219 (57%) and aged between 5 and 10 years 259 (67.4%). Out of the 384 participants, 134 (34.9%) and 255 (66.4%) suffered from lymphadenopathy and tonsil hyperplasia, respectively. Interestingly, lymphadenopathy and tonsil hyperplasia were more (P 0.05) in the 5–10 age group than those aged 11–16 years. Moreover, 41.4% of the participants were infected by a GAS sore throat. GAS sore throat is significantly associated with lymphadenopathy (AOR: 2.375, 95% CI: 1.479–3.815, P 0.000) and tonsil hyperplasia (AOR: 3.374, 95% CI: 1.939–5.874, P 0.000). Notably, males (AOR: 0.853, 95% CI: 0.549–1.325, P 0.479) and individuals aged 5–10 years (AOR: 0.867, 95% CI: 0.464–1.618, P 0.654) were less likely to have a GAS sore throat. In our study, all isolated strains were sensitive to penicillin. Clindamycin, azithromycin, and erythromycin resistance were observed in 7 (4.4%), 44 (27.7%), and 47 (29.6%) isolates, respectively.Conclusion: The study displayed the current situation of GAS sore throat in the White Nile state. Penicillin was found to be the effective drug to cure S. tonsillitis but a high rate of resistance to macrolides was noticed which is an alarming sign.

PHENOTYPIC DETECTION OF INDUCIBLE CLINDAMYCIN RESISTANCE IN STAPHYLOCOCCUS SPECIES ISOLATED FROM CLINICAL SAMPLES IN A TERTIARY CARE HOSPITAL

Introduction: Clindamycin is an effective drug used as an alternative to Vancomycin to treat skin and soft tissue infections caused by Staphylococcus spp. Reporting Staphylococcus as susceptible to Clindamycin without checking for inducible Clindamycin resistance may lead to therapeutic failure. Aim: To detect inducible Clindamycin resistance (MLSBi) among clinical isolates of Staphylococci by using a simple double-disc diffusion test (D-test). Methods: It was a prospective study conducted for 6 months from June 2022 to November 2022. All the Staphylococcal isolates from various samples were taken . Inducible clindamycin resistance (MLSBi) was detected by Erythromycin and Clindamycin disc approximation test (D-test) following CLSI guidelines. Results: A total of 216 Staphylococcus species were isolated from different samples. Out of the total samples Staphylococcus aureus were 42% and Coagulase negative Staphylococcus (CoNS) were 58%. Sensitivity to vancomycin, linezolid and teicoplanin were 100%. Methicillin resistance is seen in 21% of Staphylococcus aureus and 23% of CoNS. The different susceptibility patterns to clindamycin in both Staphylococcus aureus and CoNS were noted. Constitutive (MLSBc) phenotype was most prevalent (48%) followed by MS phenotype (43%) and inducible (MLSBi) phenotype (9%) among Erythromycin resistant Staphylococcus isolates. Sensitive phenotype (S) is detected in 27%. MLSBi was more frequent in Methicillin Resistant Staphylococcus aureus (MRSA) (28%) and MRCoNS (10%) than in MSSA (4%) and MSCoNS (2%). Conclusion: D-test should be included as a mandatory method in routine disc diffusion antimicrobial testing to detect inducible Clindamycin resistance in Staphylococci for the optimum treatment of patients.

Prevalence and molecular characterization of methicillin resistant Staphylococcus aureus (MRSA) and vancomycin resistant Staphylococcus aureus (VRSA) in a tertiary care hospital

Resistance shown by Staphylococcus aureus to methicillin; mediated by mecA, and vancomycin; mediated by vanA, has led to difficulty in treatment of related infections. Despite reports showing methicillin resistant S. aureus (MRSA) and vancomycin resistant S. aureus (VRSA) in Nepal, and need for their regular surveillance, no study has been conducted on it in our hospital. So, this study is aimed to determine prevalence of MRSA, VRSA and their molecular characterization along with antibiogram. A descriptive cross-sectional study was conducted from August to December, 2022 in Clinical Microbiology Laboratory of NMCTH among S. aureus (n=160) isolated from various clinical specimens after receiving ethical approval from NMC-IRC. AST was done by modified Kirby-Bauer’s disc diffusion method. MRSA and VRSA were detected by cefoxitin disc method and agar dilution method respectively. Inducible clindamycin resistance was detected by D-test. Resistant genes (mecA, PVL, and vanA) were detected using conventional PCR. Prevalence of MRSA was found to be 31.2% (50/160) but none of the isolates were resistant to vancomycin. Total 7 (46.6%) mecA and 7 (46.6%) PVL genes were detected among 15 selected MRSA isolates but vanA was not found. All the MRSA isolates were susceptibile to co-trimoxazole, tigecycline, chloramphenicol, vancomycin, teicoplanin and linezolid. The resistance rate against ciprofloxacin, ofloxacin, and clindamycin was 52.0%, 44.0%, and 68.0% (20.0% iMLSB, 28.0% cMLSB and 16.0% MS-phenotypes) respectively. Prompt implementation of hospital antibiotic policy and AMR Act by government along with regular surveillance of MRSA and VRSA seems essential to contain MRSA infections. Co-trimoxazole could be treatment option against MRSA in our setting, keeping vancomycin in reserve. However, large scale studies are required to establish this conclusion.

Increased frequency of clindamycin-resistant Cutibacterium acnes strains isolated from Japanese patients with acne vulgaris caused by the prevalence of exogenous resistance genes.

Cutibacterium acnes, a resident bacterium of the skin, is a target for antimicrobial treatment of acne vulgaris, because it exacerbates inflammation. Recently, antimicrobial-resistant C. acnes strains have been isolated worldwide, and their prevalence has led to failure of antimicrobial treatment. This study aimed to analyze the antimicrobial resistance of C. acnes strains isolated from Japanese patients with acne vulgaris who visited the hospital and dermatological clinics between 2019 and 2020. Resistance rates to roxithromycin and clindamycin increased during 2019 to 2020 compared with those during 2013 to 2018. Additionally, the proportion of doxycycline-resistant and low-susceptibility strains (minimum inhibitory concentration [MIC] ≥8μg/mL) increased. No difference in clindamycin resistance rates between patients with and without a history of antimicrobial use was observed during 2019 to 2020, which were significantly higher for patients with a history than for patients without a history during 2016 to 2018. The proportion of high-level clindamycin-resistant strains (MIC ≥256 μg/mL) gradually increased; particularly, the resistance rate was 2.5 times higher in 2020 than that in 2013. The proportion of strains showing high-level clindamycin resistance that also have the exogenous resistance genes erm(X) or erm(50), which confer high resistance, showed a strong positive correlation (r=0.82). Strains with the multidrug resistance plasmid pTZC1 encoding erm(50) and tet(W) genes were frequent in clinic patients. Notably, most strains with erm(X) or erm(50) were classified as single-locus sequence types A and F (traditional types IA1 and IA2). Our data show that the prevalence of antimicrobial-resistant C. acnes is increasing in patients with acne vulgaris attributable to acquisition of exogenous genes in specific strains. To control the increasing prevalence of antimicrobial-resistant strains, it is important to select the appropriate antimicrobials while taking into consideration the latest information on resistant strains.

Inhibition of Erythromycin and Erythromycin-Induced Resistance among Staphylococcus aureus Clinical Isolates.

The increasing incidence of erythromycin and erythromycin-induced resistance to clindamycin among Staphylococcus aureus (S. aureus) is a serious problem. Patients infected with inducible resistance phenotypes may fail to respond to clindamycin. This study aimed to identify the prevalence of erythromycin and erythromycin-induced resistance and assess for potential inhibitors. A total of 99 isolates were purified from various clinical sources. Phenotypic detection of macrolide-lincosamide-streptogramin B (MLSB)-resistance phenotypes was performed by D-test. MLSB-resistance genes were identified using PCR. Different compounds were tested for their effects on erythromycin and inducible clindamycin resistance by broth microdilution and checkerboard microdilution methods. The obtained data were evaluated using docking analysis. Ninety-one isolates were S. aureus. The prevalence of constitutive MLSB, inducible MLSB, and macrolide-streptogramin (MS) phenotypes was 39.6%, 14.3%, and 2.2%, respectively. Genes including ermC, ermA, ermB, msrA, msrB, lnuA, and mphC were found in 82.6%, 5.8%, 7.7%, 3.8%, 3.8%, 13.5%, and 3.8% of isolates, respectively. Erythromycin resistance was significantly reduced by doxorubicin, neomycin, and omeprazole. Quinine, ketoprofen, and fosfomycin combated and reversed erythromycin/clindamycin-induced resistance. This study highlighted the significance of managing antibiotic resistance and overcoming clindamycin treatment failure. Doxorubicin, neomycin, omeprazole, quinine, ketoprofen, and fosfomycin could be potential inhibitors of erythromycin and inducible clindamycin resistance.

Phenotypic and Genotypic Characterization of Macrolide-Lincosamide-Streptogramin Resistance in Staphylococcus aureus Isolates from Bovine and Human

Abstract In this study, penicillin, oxacillin, and macrolide-lincosamide-streptogramin (MLS) resistance in S. aureus strains that were isolated from bovine mastitis cases, and human patients were investigated. Inducible clindamycin resistance (iML) was not found in 30 bovine isolates, while it was detected in 3 (10%) of 30 human isolates. MIC90 values of penicillin, oxacillin and macrolide-lincosamides (ML) were 2, 0.19, &gt;256 µg/ml in bovine isolates and were 3, 3 and 0.19-1.5 µg/ml in human isolates, respectively. Streptogramin resistance was not found in both bovine and human isolates. Although the mecA gene was detected in all of the oxacillin resistant isolates, blaZ gene could not be detected in penicillin resistant isolates. The erm(B) gene was detected in 5 (38.6%) of 13 ML-resistant bovine isolates, and the mph(C) gene was detected in 2 (66.66%) of 3 human isolates. As a result, resistance to penicillin and oxacillin was found to be higher in human S. aureus isolates, while ML resistance was found to be higher in bovine isolates in this investigation. It was concluded that the presence of genes in extra-chromosomal elements associated to penicillin and macrolide resistance should be investigated. The data obtained from this study will contribute to the studies on antimicrobial susceptibility in the field of human and veterinary medicine.

Occurrence of Staphylococcus spp. in the wastewaters from Iran: Diversity, antimicrobial resistance, and virulence potential

Abstract The prevalence, antibiotic resistance, and virulence characteristics of Staphylococci from hospitals, livestock, municipals, and poultry wastewaters were investigated in Ardabil, Iran. From 155 staphylococcal isolates, 44.5% were coagulase-positive Staphylococcus (CoPS) and 55.5% were coagulase-negative Staphylococcus (CoNS) spp. Both CoPS and CoNS species were mainly found in hospital and poultry wastewater samples. The most prominent CoPS and CoNS species were Staphylococcus aureus at 80% and Staphylococcus xylosus at 37%. Methicillin resistance was found in 2% of S. aureus isolates. Overall, 49.2% of CoPS and 47.6% of CoNS isolates exhibited multidrug resistance phenotypes. CoPS isolates were the most resistant to penicillin (89%) and erythromycin (62%) and CoNS isolates exhibited the highest resistance to erythromycin (55%) and tetracycline (49%). Inducible clindamycin resistance was detected in 11% of S. aureus isolates. The ermC and aac genes were detected as the most common macrolide–lincosamide–streptogramin B and aminoglycoside-resistance encoding genes in 82.5 and 22.5% of S. aureus isolates, respectively. Most of the S. aureus isolates were positive for multiple virulence factors. The methicillin-resistant S. aureus isolates belonged to SCCmec type V. A new spa type t19215 was also identified. The occurrence of multidrug-resistant S. aureus with diverse genetic resistance and virulence background in wastewater is of great health concern.

Staphylococcus aureus in Horses in Nigeria: Occurrence, Antimicrobial, Methicillin and Heavy Metal Resistance and Virulence Potentials

Staphylococcus aureus was isolated from a total of 360 nasal and groin skin swabs from 180 systematic randomly-selected horses slaughtered for meat at Obollo-Afor, Enugu State, Southeast Nigeria and antimicrobial, methicillin and heavy metal resistance profile and virulence potentials of the isolates established. Baird-Parker agar with egg yolk tellurite was used for S. aureus isolation. S. aureus isolates were confirmed biochemically and serologically using a specific S. aureus Staphytect Plus™ latex agglutination test kit. The antimicrobial resistance profile, methicillin, vancomycin and inducible clindamycin resistance, and β-lactamase production of the isolates were determined with disc diffusion. Tolerance to Copper, Cadmium, Lead and Zinc was assessed using the agar dilution method and virulence potentials were determined using phenotypic methods. Forty-three (23.9%) of the 180 horses harbored S. aureus. Some 71 S. aureus were recovered from the 360 samples. Two (2.8%) of the 71 S. aureus were methicillin-resistant S. aureus (MRSA) and 69 (97.2%) were methicillin-susceptible. MRSA was recovered from 2 (1.1%) of the 180 horses. Some 9.4% of the isolates were multiple drug-resistant (MDR). The mean multiple antibiotic resistance indices (MARI) for the isolates was 0.24. Heavy metal resistance rate of the isolates ranged between 35.4-70.4%. The isolates, including the MRSA strains, displayed virulence potentials as clumping factor and catalase, gelatinase, caseinase, heamolysin, and biofilm was at the rate of 100%, 53.5%, 43.7%, 18.3% and 23.9%, respectively. This study showed that a considerable percentage of horses slaughtered in Obollo-Afor Southeastern Nigeria are potential reservoirs of virulent multiple drug- and heavy metal-resistant S. aureus, including MRSA, that could spread to humans and the environment.

Antibiotic resistance genes and molecular typing of Streptococcus agalactiae isolated from pregnant women

BackgroundThe antibiotic resistance of genital tract colonizing Streptococcus agalactiae in pregnant women is increasing. We aimed to determine the antibiotic resistance genes of different clonal types of this bacterium in pregnant women.MethodsFour hundred twenty non-repeated vaginal and rectal specimens were collected from pregnant women and were transferred to the laboratory using Todd Hewitt Broth. The samples were cultured on a selective medium, and the grown bacteria were identified by standard microbiological and biochemical tests. Antimicrobial resistance pattern and inducible clindamycin resistance of the isolates were determined using the disk agar diffusion method. The genomic DNAs of S. agalactiae strains were extracted using an extraction kit, and the antibiotic resistance genes and RAPD types were detected using the PCR method.ResultsThe average age of the participants was 30.74 ± 5.25 years. There was a significant relationship between the weeks of pregnancy and the number of positive bacterial cultures (P-value < 0.05). Moreover, 31 pregnant women had a history of abortion, and 18 had a history of membrane rupture. Among 420 specimens, 106 S. agalactiae isolates were detected. The highest antibiotic resistance rate was found against tetracycline (94.33%), and all isolates were susceptible to linezolid. Moreover, 15, 15, 42, and 7 isolates showed an iMLSB, M-, cMLSB, and L-phenotype. The ermB was the most prevalent resistance gene in the present study, while 38 (35.84%), 8 (7.54%), 79 (74.52%), 37 (34.9%), and 20 (18.86%) isolates were contained the ermTR, mefA/E, tetM, tetO, and aphA3 gene, respectively.ConclusionsThe high-level antibiotic resistance and prevalence of resistance genes may be due to the arbitrarily use, livestock industry consumption, and the preventive use of antibiotics in pregnant women. Thus, the need to re-considering this problem seems to be necessary.

National Surveillance of Tetracycline, Erythromycin, and Clindamycin Resistance in Invasive Streptococcus pyogenes: A Retrospective Study of the Situation in Spain, 2007-2020.

This work reports on antimicrobial resistance data for invasive Streptococcus pyogenes in Spain, collected by the 'Surveillance Program for Invasive Group A Streptococcus', in 2007-2020. emm typing was determined by sequencing. Susceptibility to penicillin, tetracycline, erythromycin, and clindamycin was determined via the E-test. tetM, tetO, msrD, mefA, ermB, ermTR, and ermT were sought by PCR. Macrolide-resistant phenotypes (M, cMLSB, and iMLSB) were detected using the erythromycin-clindamycin double-disk test. Resistant clones were identified via their emm type, multilocus sequence type (ST), resistance genotype, and macrolide resistance phenotype. Penicillin susceptibility was universal. Tetracycline resistance was recorded for 237/1983 isolates (12.0%) (152 carried only tetM, 48 carried only tetO, and 33 carried both). Erythromycin resistance was detected in 172/1983 isolates (8.7%); ermB was present in 83, mefA in 58, msrD in 51, ermTR in 46, and ermT in 36. Clindamycin resistance (methylase-mediated) was present in 78/1983 isolates (3.9%). Eight main resistant clones were identified: two that were tetracycline-resistant only (emm22/ST46/tetM and emm77/ST63/tetO), three that were erythromycin-resistant only (emm4/ST39/mefA-msrD/M, emm12/ST36/mefA-msrD/M, and emm28/ST52/ermB/cMLSB), and three that were tetracycline-erythromycin co-resistant (emm11/ST403/tetM-ermB/cMLSB, emm77/ST63/tetO-ermTR/iMLSB, and emm77/ST63/tetM-tetO-ermTR/iMLSB). Tetracycline, erythromycin, and clindamycin resistance rates declined between 2007 and 2020. Temporal variations in the proportion of resistant clones determined the change in resistance rates.

Prevalence, antimicrobial susceptibility, and antibiotic resistance gene transfer of Bacillus strains isolated from pasteurized milk.

Pasteurization is carried out in dairy industries to kill harmful bacteria present in raw milk. However, endospore-forming bacteria, such as Bacillus, cannot be completely eliminated by pasteurization. In this study, a total of 114 Bacillus strains were isolated from 133 pasteurized milk samples. Antibiotic susceptibility tests showed that the percentage of Bacillus with intrinsic resistance to ampicillin and penicillin were 80 and 86%, respectively. Meanwhile, some Bacillus isolates had acquired resistance, including trimethoprim-sulfamethoxazole resistance (10 isolates), clindamycin resistance (8 isolates), erythromycin resistance (2 isolates), and tetracycline resistance (1 isolate). To further locate these acquired resistance genes, the plasmids were investigated in these 16 Bacillus strains. The plasmid profile indicated that Bacillus cereus BA008, BA117, and BA119 harbored plasmids, respectively. Subsequently, the Illumina Novaseq PE150 was applied for the genomic and plasmid DNA sequencing. Notably, the gene tetL encoding tetracycline efflux protein was found to be located on plasmid pBC46-TL of B. cereus BA117. In vitro conjugative transfer indicated that pBC46-TL can be transferred into Bacillus invictae BA142, Bacillus safensis BA143, and Bacillus licheniformis BA130. The frequencies were of 1.5 × 10-7 to 1.7 × 10-5 transconjugants per donor cells. Therefore, Bacillus strains with acquired antibiotic resistance may represent a potential risk for the spread of antibiotic resistance between Bacillus and other clinical pathogens via horizontal gene transfer.

Antibiotic Sensitivity of Group B Streptococcus from Pregnant Mothers and Its Association with Resistance Genes

Objective: This study assessed the antibiotic susceptibility and characterized antibiotic resistance genes of group B Streptococcus (GBS) isolates from selected tertiary care hospitals in Western Province, Sri Lanka. Methods: A descriptive cross-sectional study was carried out to determine antibiotic sensitivity of GBS among 175 pregnant women of >35 weeks of gestation attending antenatal clinics in four teaching hospitals. Low vaginal and rectal swabs were collected separately, and GBS was identified by standard microbiological methods. Antibiotic sensitivity and minimum inhibitory concentration (MIC) were performed according to Clinical and Laboratory Standards Institute (CLSI) guidelines. DNA was extracted from culture isolates, and antibiotic-resistant genes were identified by polymerase chain reaction using ermB, ermTR, mefA, and linB genes. Results: GBS colonization in the study sample was 25.7% (45/175) with detection rate of 22.9% (40/175) and 2.9% (5/175) in vaginal and rectal samples, respectively. All isolates were susceptible to penicillin with an MIC range of 0.03–0.12 μg/mL. Six isolates (13.3%) were intermediate, and 11 isolates (24.4%) were resistant to erythromycin. There were 5 intermediately resistant isolates (11.1%) and 10 resistant isolates (22.2%) for clindamycin. Of them, seven had inducible clindamycin resistance (iMLS_B). MIC range of erythromycin was 0.03–0.32 μg/mL and that of clindamycin was 0.06–0.32 μg/mL. ermB gene was detected in 7 (15.5%). ermTR gene was found in 16 (35.6%) and was significantly associated with iMLS_B phenotype (p = 0.005). mefA gene was detected in two (4.4%) isolates, while linB gene was not detected in tested isolates. Conclusion: All isolates were sensitive to penicillin, and the most prevalent resistance genotype was ermTR in the study population.

Prevalence, antibiotic and heavy metal resistance of Vibrio spp. isolated from the clam Meretrix meretrix at different ages in Geligang, Liaohe estuary in China

Vibrio as one of the main pathogens of shellfish diseases can cause serious human seafoodborne gastroenteritis and even death. In this study, we analyzed the bacterial communities from the clam, and compared the resistance phenotypes and genotypes of Vibrio spp. from Meretrix meretrix at different growth stages. High-throughput sequencing analysis revealed the predominance of Proteobacteria (50%) in the bacterial community and Vibrio was one of the dominant genera in the clam hepatopancreas in the summer. Vibrio abundance in Meretrix meretrix positively correlated with the water temperature (p&amp;lt;0.05). A total of 73 Vibrio isolates from Meretrix meretrix were classified into 19 species and the dominant strains included V. mediterranei (19%) and V. harveyi (11%), V. algolyticus (10%), and V. parahaemolyticus (8%). The species and abundance of Vibrio spp. were the highest in the 3-year-old of Meretrix meretrix compared with clams of other ages in the summer. Among the 73 isolates, 68 Vibrio strains were resistant to other 15 antibiotics except for sulfamethoxazole-trimethoprim with 57 resistant phenotypes. The most prevalent resistance was toward clindamycin (76%), followed by amikacin (63%), ampicillin (62%), rifampicin (62%), vancomycin (57%), and amoxicillin (50%). The ARI values of Vibrio spp. in different ages ranged from 0.13 to 0.18, and ARI values of 3-year-old (ARI=0.18) clams are higher than that of other ages clam. Approximately 72% of the resistant isolates showed multidrug-resistant phenotypes with maximum resistance to 15 antibiotics. Tolerance to heavy metals including Cd, Zn, and Cu was detected in the majority of antibiotic resistant isolates. In addition to the co-resistance to the same class of antibiotics, resistance to cephalosporin (CFP, CEP, CZ) were significantly correlated with penicillins (AMP, AMC) (p&amp;lt; 0.01), tetracycline (p &amp;lt; 0.001), sulfanilamide (SXT) (p&amp;lt; 0.01) and quinolone (CIP) (p&amp;lt; 0.01). The heavy metal resistance genes copB and nccA were significantly correlated with the clindamycin resistance phenotype (p&amp;lt;0.01). This study revealed that the habitat of Meretrix meretrix is in low exposure to antibiotics, and a link between heavy metal resistance genes and antibiotic resistance.

550. Analysis of Staphylococcus aureus resistance patterns and antibiotic prescribing practices in a single tertiary pediatric center in South Florida

Abstract Background Staphylococcus aureus antibiotic resistance in pediatric populations is a dynamic problem that affects the morbidity and mortality of all children. Local efforts to understand its patterns as well as the antibiotic prescribing trends, as well as their relationship, are cornerstone for the development of mitigation strategies. Methods We conducted a retrospective observational study of 11,964 clinical isolates at a tertiary pediatric care center in South Florida collected from 2008 to 2019 to determine the antibiotic susceptibility of Staphylococcus aureus, compare antibiotic resistance patterns between MRSA and MSSA isolates and evaluate antibiotic prescribing practices from 2013 to 2019. Results Methicillin resistance was present in 47.9% (±0.63) isolates with no significant temporal trend. Resistance to clindamycin was on average 24.8% (±1.08), to erythromycin 66.9% (±1.68), to levofloxacin 35.5% (±1.61) and to gentamicin 6.8% (±1.11). MRSA isolates had higher resistance rates to most antibiotics than MSSA (p&amp;lt; 0.05) except for clindamycin for which both had similar rates. Resistance to clindamycin and gentamicin increased significantly from 20% to 25% and from 5 to 15%, respectively, among MRSA and quinolone resistance rose among MSSA from 7% to 13%. Antibiotic prescription rate increased from 56 prescriptions per 1,000 patients to 136 prescriptions per 1,000 patients from 2013 to 2019. There was a positive correlation between erythromycin resistance rate among MRSA and macrolide prescription frequency (p&amp;lt; 0.05). Figure 1.Antibiotic resistance in S aureus isolates from pediatric patients between 2008 and 2019. The trends in erythromycin and gentamicin resistance were statistically significant (p&amp;lt;0.05); all other trends shown were not significant. Figure 2.Comparative annual resistance rate among MSSA and MRSA isolates from pediatric patients between 2008 and 2019 The trend in levofloxacin resistance among MSSA was statistically significant, as well as the trends in erythromycin, clindamycin, and gentamicin in MRSA; all other trends were not significant. Figure 3.Annual antibiotic prescription frequency as a percent of all antibiotics prescribed in outpatient facilities and emergency department at Nicklaus Children’s Hospital between 2013 and 2019Beta-Lactams are expressed as the summation of cephalosporins and penicillins. The frequency at which penicillins, cephalosporins and macrolides were prescribed changed significantly; all other frequencies did not change significantly. Conclusion Pediatric Staphylococcus aureus isolates showed high and stable rates of methicillin resistance during the study period. There is growing clindamycin and gentamicin resistance among MRSA isolates as well as increasing levofloxacin resistance in MSSA isolates. Antibiotic prescribing increased significantly in this population during the study period in South Florida. Disclosures All Authors: No reported disclosures.

Plasmid-Coded Linezolid Resistance in Methicillin-Resistant Staphylococcus aureus from Food and Livestock in Germany

Resistance of methicillin-resistant Staphylococcus aureus (MRSA) from food and livestock to last resort antibiotics such as linezolid is highly concerning, since treatment options for infections in humans might be diminished. Known mechanisms of linezolid resistance include point mutations in the 23S rRNA gene and in the ribosomal proteins L3, L4 and L22 as well as an acquisition of the cfr, optrA or poxtA gene. The objective of our study was to characterize antimicrobial resistance (AMR) determinants and phylogenetic relationships among linezolid-resistant (LR-) MRSA from food and livestock. In total, from more than 4000 incoming isolates in the years 2012 to 2021, only two strains from 2015 originating from pig samples exhibited linezolid resistance in the antimicrobial susceptibility testing with MICs of ≥8 mg/L. These LR-MRSA were characterized in detail by whole-genome sequencing and phylogenetic analyses using cgMLST. The LR-MRSA strains showed resistances to ten and eight different antibiotics, respectively. Both strains harbored plasmid-coded cfr genes mediating the linezolid resistance. The cfr genes showed identical sequences in both strains. In addition to the cfr gene, genes for phenicol and clindamycin resistance were detected on the respective plasmids, opening the possibility for a co-selection. The LR-MRSA differed distantly in the phylogenetic analyses and also to other MRSA from pig samples in the year 2015. In conclusion, the occurrence of LR-MRSA in food and livestock seems to be very rare in Germany. However, carriage of plasmids with linezolid resistance determinants could lead to further linezolid-resistant strains by horizontal gene transfer.