Clindamycin Resistance Research Articles

Revealing inducible clindamycin resistance in methicillin-resistant S aureus : A vital diagnostic imperative for effective treatment.

The World Health Organization added methicillin-resistant S aureus (MRSA) to the list of "priority pathogens," given its capacity to cause life-threatening infections. Clindamycin is a preferred treatment for non-complicated S aureus-induced skin and soft tissue infections. Its good tissue penetration and oral absorption make it suitable for outpatient therapy. However, the emergence of inducible and constitutive (MLS B ) resistance led to clinical challenges, primarily due to the potential oversight of inducible resistance in routine antimicrobial sensitivity testing. This cross-sectional study was conducted at a tertiary care hospital during 2020-2022. A total of 158 MRSA isolates from various clinical specimens were analyzed. The Kirby-Bauer disk diffusion method using cefoxitin disk and D-test were used to identify MRSA and detect inducible clindamycin resistance (ICR), respectively. Among the 158 MRSA isolates, 34.17% showed constitutive clindamycin resistance (MLS B c), while 22.15% displayed ICR (MLS B i). In addition, 10.13% of isolates demonstrated the MS phenotype, clindamycin, and erythromycin susceptibility, with 53 (33.54%) isolates susceptible to both antibiotics. The relative risk of clindamycin treatment failure was 7.66 times higher if the D-test was not used. To prevent clindamycin treatment failures, the D-test must be implemented to detect ICR in MRSA isolate. Neglecting simple and cost-effective tests may lead to inaccurate susceptibility reporting, jeopardizing treatment success.

Regulation of erm(T) MLSB phenotype expression in the emergent emm92 type group A Streptococcus

In the last decade, invasive group A Streptococcus (iGAS) infections have doubled in the US, with equivalent increases in MLSB (macrolide, lincosamide, and streptogramin B)-resistance. The emm92-type isolates carrying the erm(T) gene have been associated with an alarming emergence of iGAS infections in people who inject drugs or experience homelessness. Our goal was to elucidate the mechanisms behind inducible (iMLSB) and constitutive (cMLSB) resistance in emm92 isolates. Sequence analysis identified polymorphisms in the erm(T) regulatory region associated with cMLSB resistance. RT-qPCR and RNAseq revealed increased erm(T) mRNA levels in iMLSB isolates in response to erythromycin exposure, while cMLSB isolates exhibited high erm(T) expression independent from antibiotic exposure. Transcription results were coupled with shifting levels of ribosomal methylation. A homology model of the ErmT enzyme identified structural elements and residues conserved in methyltransferases. Delayed growth of iMLSB isolates cultured with erythromycin and increased clindamycin resistance in cMLSB isolates were observed.

Changes in the epidemiology of neonatal bacteremia during the COVID-19 pandemic in Wuhan, China.

To investigate the incidence, pathogen distribution, and antibiotic susceptibility of early- and late-onset neonatal bacteremia, and to analyze pathogen trends before and during the COVID-19 pandemic. Between January 2016 to December 2022, we collected 879 blood and cerebrospinal fluid specimens from newborns with bacteremia. Bacterial identification used biochemical methods and MALDI-TOF, and antibiotic susceptibility was tested with the VITEK 2 system. Incidence per 1,000 admissions was calculated with Wilson's 95% confidence intervals, and categorical variables were compared using χ²-test or Fisher's exact test. Early-onset bacteremia incidence was 2.6 per 1,000 admissions, and late-onset bacteremia was 26.3, with a significant decline from 70.7 to 10.5 per 1,000 admissions over the study period. Late-onset bacteremia was more common before COVID-19, while early-onset bacteremia increased during the pandemic. The top five pathogens were CoNS(39.9%), E. faecalis(17.7%), E. faecium(13.7%), E. coli(8.4%), and GBS(5.8%). During the COVID-19 pandemic, the incidence of CoNS and S. aureus infections significantly decreased. Throughout the entire study period, CoNS and S. aureus showed high resistance to penicillin G and erythromycin but were sensitive to vancomycin and linezolid. E. faecalis and E. faecium were susceptible to vancomycin, linezolid, and teicoplanin but resistant to erythromycin, tetracycline, and rifampin. MRCoNS and MRSA were detected in 72.7% and 31.0% of isolates, respectively. Resistance rates of E. faecium and E. faecalis to ampicillin decreased significantly, clindamycin resistance in GBS decreased during the pandemic. This study highlights notable shifts in neonatal bacteraemia patterns during the COVID-19 Pandemic that were likely influenced by increased infection control and disruptions in maternal care, leading to changes in pathogen distribution and antimicrobial resistance.

Antimicrobial resistance in Staphylococcus aureus and Enterococci spp. isolates from bloodstream infections in Australian children, 2013 - 2021.

Rising proportions of antimicrobial resistance (AMR) have been observed in both Staphylococcus aureus and Enterococcus spp. isolates. The Australian Group on Antimicrobial Resistance (AGAR) surveillance program captures clinical and microbiological data of isolates detected in blood cultures across Australia. EUCAST 2022 was used for MIC interpretation and the AMR package in R for data analysis. There were 2,091 BSIs with S. aureus and 534 enterococcal BSI episodes over the nine years. Three-quarters of S. aureus BSI episodes were community-onset (78.3%) whilst more than half of enterococcal BSIs were hospital-onset (56.9%). The median age for S. aureus BSIs was 6 years, whilst >50% enterococcal BSIs were in children <12 months old.Fifteen percent of S. aureus isolates were methicillin-resistant (MRSA). Overall, 85.3% of S. aureus were resistant to penicillin, 12.5% resistant to erythromycin, 10.3% to clindamycin, and 4.7% to ciprofloxacin. Resistance to penicillin decreased over time whilst clindamycin resistance increased.Resistance in Enterococcus spp. was almost entirely observed in E. faecium; only one E. faecalis isolate was ampicillin resistant, and no E. faecalis isolates were vancomycin or teicoplanin resistant. Seventy-three percent of E. faecium were resistant to ampicillin, 25.5% to vancomycin (VREfm) and 8.8% to teicoplanin. Significant shifts in the epidemiology and resistance profiles of S. aureus and Enterococcus spp. BSIs in Australian children were observed, making clear the importance of age-stratified reporting in antimicrobial resistance data.

Prevalence and factors associated with human colonisation and vancomycin minimum inhibitory concentration of &lt;em&gt;Staphylococcus aureus&lt;/em&gt; in Colombo, Sri Lanka

Introduction: Staphylococcus aureus is known to cause a wide variety of diseases of varying severity in humans. The objectives of this study were to determine the prevalence of S. aureus and methicillin resistant S. aureus (MRSA) colonisation, assess factors associated with MRSA colonisation, identify antibiotic susceptibility patterns of MRSA isolates, determine distribution of vancomycin minimum inhibitory concentrations (MIC) of S. aureus and factors associated with high vancomycin MIC values (≥2 µg/ml). Methods: A descriptive cross sectional study was conducted among 341 participants aged 18 to 84 years selected randomly from the Colombo district from 11th December 2018 to 10th April 2019. Samples were collected from the nose, axilla, groin of participants and identification and sensitivity testing of S. aureus were performed based on standard operation procedures given in the Laboratory manual in microbiology published by the Sri Lanka College of Microbiologists (2011). Results: Prevalence of S. aureus and MRSA colonisation in the sample population was 34.6% and 13.78% respectively. All MRSA isolates were susceptible to linezolid. MRSA susceptibility to gentamicin (86%), co-trimoxazole (88 %), and chloramphenicol (80%) was high. Erythromycin had the lowest susceptibility (20%). Inducible clindamycin resistance was demonstrated in 31% of isolates. Meat consumption and consumption of antibiotics within the previous six months showed a significant association with MRSA colonisation. Vancomycin MIC of S. aureus ranged from ≤ 0.5 to 2 µg/ml. Conclusion: As prevalence of MRSA colonisation is 13.78%, more attention should be paid when managing patients with suspected S. aureus infections presenting from the community. Further research on associated factors and environmental triggers are warranted with a larger sample size and different study design to formulate national regulations and guidelines.

Adjunctive linezolid versus clindamycin for toxin inhibition in β-lactam-treated patients with invasive group A streptococcal infections in 195 US hospitals from 2016 to 2021: a retrospective cohort study with target trial emulation

Adjunctive clindamycin use is associated with survival in invasive group A streptococcus (GAS) infections but increasing clindamycin resistance in GAS has called into question its durability for this indication. Linezolid also inhibits GAS toxin and virulence factor production, but clinical efficacy data remain sparse. We retrospectively emulated a target multicentre, non-blinded, non-inferiority trial to assess the efficacy of adjunctive linezolid compared with clindamycin in adult inpatients with invasive GAS infection treated with a β-lactam using the PINC AI database between 2016 and 2021. Patients were eligible if they had a monomicrobial GAS culture and received adjunctive therapy within 3 days of culture either concurrently or after β-lactam initiation and completed at least 3 days of β-lactam therapy. The primary outcome was adjusted risk ratio (aRR) of in-hospital mortality assessed by overlap-weighting using propensity scores. Secondary outcomes were length of stay among survivors and Clostridium difficile infection. Of 1095 β-lactam-treated patients with GAS, 829 (76%) received clindamycin and 266 (24%) received linezolid. In the overlap weighted cohort, the receipt of linezolid was not associated with a statistically significant different aRR of in-hospital mortality compared with clindamycin (linezolid: 9·8% [26/266] vs clindamycin: 7·0% [58/829]; aRR: 0·92 [95% CI 0·42 to 1·43]; p=0·76). The risk difference was -0·005 (95% CI -0·05 to 0·04; p=0·81) and fell within the non-inferiority margin of 0·05. The primary analysis results were consistent across important subgroups and sensitivity analyses. Among survivors, median length of stay (adjusted ratio 0·96 [95% CI 0·16 to 0·08]; p=0·47) and C difficile infection risk (aRR 1·76 [95% CI 0·37 to 1·75]; p=0·29) were not statistically significantly different between the two groups. In this emulated trial of adult patients with invasive GAS infections treated with β-lactam, linezolid appeared non-inferior to clindamycin suggesting linezolid as an alternative for adjunctive antitoxin therapy. The Intramural Research Program of the US National Institutes of Health Clinical Center and the National Institute of Allergy and Infectious Disease.

Unveiling the genetic landscape of Streptococcus agalactiae bacteremia: emergence of hypervirulent CC1 strains and new CC283 strains in Tehran, Iran

BackgroundThe emergence of Streptococcus agalactiae infections in patients with bacteremia is increasing. It is crucial to investigate the epidemiology, molecular characteristics, biofilm status, and virulence analysis of Streptococcus agalactiae in these patients.MethodsIn this cross-sectional study, 61 S. agalactiae isolated from blood infection were subjected to characterization through antimicrobial susceptibility tests, biofilm formation, multilocus sequence typing (MLST), and PCR analysis for detecting resistance (tet and erm family) and virulence genes (alp2/3, alp4, bca, bac, eps, rib, lmb, cylE, and pilus island genes).ResultsOverall, 32.7% of the isolates demonstrated an inducible clindamycin resistance phenotype. The results showed that 49.2, 24.6, and 8.2% of confirmed Streptococcus agalactiae strains were classified as strong, intermediate, and weak biofilm-forming strains, respectively. tet(M) (57.1%) was recovered most, followed by tet(M) + tet(L) (14.3%), tet(S) + tet(K) (10.7%), tet(M) + tet(K) (8.9%), tet(M) + tet(K) + tet(O) (5.4%), and tet(S) + tet(L) + tet(O) (3.6%). Three virulence gene profiles of cylE, lmb, bca, rib (24.6%; 15/61), cylE, lmb, rib, alp3 (19.7%; 12/61), and cylE, lmb, bac, rib (16.4%; 10/61) were detected in approximately two-thirds of the isolates. MLST revealed that the 61 isolates belonged to six clonal complexes, including CC1 (49.2%), followed by CC12 (18%), CC19 (13.1%), CC22 (9.8%), CC17 (6.6%), and CC283 (3.3%), and 11 different sequence types (STs), including ST1 (24.6%), ST7 (14.8%), ST918 (13.1%), ST2118 (9.8%), ST19 (9.8%), ST48 (6.6%), ST1372 (4.9%), ST22 (4.9%), ST40 (4.9%), ST734 (3.3%), and ST283 (3.3%). Remarkably, all CC1 and CC12 isolates, three-fourths of CC19, and half of CC22 were confirmed as biofilm producers. Conversely, CC17 and CC28 isolates were found to be nonproducers. The occurrence of strong biofilm formation was limited to specific CCs, namely CC1 (34.4%), CC12 (8.2%), CC19 (3.3%), and CC22 (3.3%).ConclusionThe high prevalence of CC1 and CC12 clones among S. agalactiae strains reflects the emergence of these lineages as successful clones in Iran, which is a serious concern and poses a potential threat to patients.

Antibiotic susceptibility of orofacial infections in Bratislava: a 10-year retrospective study

ObjectivesAim of this study was to analyse causal microbiological agents and their bacterial resistance in orofacial infections requiring hospital admission.Materials and methodsPresented is a 10-year retrospective study of patients hospitalised at a single department in 2014–2023. 744 patients were involved. In the statistical analysis, following data was evaluated: causal microbes and their resistance to Penicillin, Amoxicillin-Clavulanate, Clindamycin and Metronidazole.ResultsMost frequent aetiology was odontogenic with causal tooth in socket (n = 468; 62,9%), followed by odontogenic – post extraction (n = 152; 20.4%), jaw fracture (n = 41; 5.5%), sialadenitis n = 31 (4.2%), osteonecrosis n = 22 (3.0%), oncological diagnosis in head and neck (n = 17; 2.3%), unknown (n = 10; 1.3%) and multiple factors (n = 3; 0.4%). 408 patients (54.8%) underwent extraoral abscess revision, 336 patients (45.2%) patients were treated locally without extraoral revision. In odontogenic group with tooth still present, superior CRP (m = 145.8 mg/l; SD = 117.7) and leukocyte values (m = 13.6*109l; SD = 6.6) were observed in comparison to other groups. There were 698 cultivated bacteria in 362 patients. Most frequent bacteria were Streptococci (n = 162; 23.2%), Prevotella (n = 83; 11.2%) and Parvimonas (n = 65; 9.3%). Clindamycin resistance was highest (n = 180 resistant bacteria; 25.8%), followed by Metronidazole (n = 178; 25.5%), Penicillin (n = 107; 15.3%) and Amoxicillin-Clavulanate (n = 34; 4.9%).ConclusionsOrofacial infections in head and neck region are mostly of odontogenic origin with causal tooth still in socket. Causal bacteria show a high antibiotic resistance rate, especially to Clindamycin and Metronidazole.Clinical RelevanceAcquired data will be used to determine guidelines for empirical antibiotic prescription in cases of orofacial infections.

Group B Streptococcus Infections in Non-Pregnant Adults, Italy, 2015-2019.

Group B Streptococcus (GBS, Streptococcus agalactiae) is a pathogen of increasing importance in adults. Severe and invasive cases in non-pregnant adults were collected during the period 2015-2019 by voluntary-based surveillance. In total, 108 GBS strains were phenotypically and genotypically characterized for the serotype, antimicrobial resistance, pili, surface protein genes, and the hyper-virulent adhesin hvgA. Patients were divided into two age groups: adults (18-64 years; n = 32) and older adults (≥65 years; n = 72). The average age was 70.8 years, with a male/female ratio of 1.7. Most isolates were recovered from cases of bacteremia (blood, n = 93), and a higher frequency of invasive GBS infections (iGBS) was found among older adults (66.7%). Serotype III was the most frequent (n = 41, 38%), followed by type Ia and type V (n = 20 each, 18.5%). Serotypes Ia, Ib, II, III, IV, and V accounted for all but one isolates (99.1%). The iGBS isolates were universally susceptible to penicillin, while the prevalence of resistance to clindamycin, erythromycin, tetracycline, and high-level gentamicin resistance was 26.8%, 24.1%, 85.2%, and 5.5%, respectively, with the predominance of the erm(B) gene for macrolide resistance and the tet(M) gene for tetracycline resistance. The associations between the serotypes/antimicrobial resistance/virulence traits underlined the increasing importance of serotype III and its contribution to antimicrobial resistance as well as the steady increase over time of serotype IV. This nationwide study confirmed the need for monitoring the GBS epidemiology in non-pregnant adults through continuous surveillance of GBS infections.

Evaluating Inducible Clindamycin Resistance in Staphylococcus aureus: The Crucial Role of the Gold Standard 'D' Zone Test in the Automated Era

Evaluating Inducible Clindamycin Resistance in Staphylococcus aureus: The Crucial Role of the Gold Standard 'D' Zone Test in the Automated Era

Accurate prediction of antimicrobial resistance and genetic marker of Staphylococcus aureus clinical isolates using MALDI-TOF MS and machine learning – across DRIAMS and Taiwan database

BackgroundThe use of matrix-assisted laser desorption/ionisation-time-of-flight mass spectra (MALDI-TOF MS) with machine learning (ML) has been explored for predicting antimicrobial resistance. This study evaluates the effectiveness of MALDI-TOF MS paired with various ML classifiers and establishes optimal models for predicting antimicrobial resistance and the presence of mecA gene among Staphylococcus aureus. Materials and MethodsAntimicrobial resistance against tier 1 antibiotics and MALDI-TOF MS of S. aureus were analysed using data from the Database of Resistance against Antimicrobials with MALDI-TOF Mass Spectrometry (DRIAMS) and one medical centre (CS database). Five ML classifiers were used to analyse performance metrics. The Shapley value quantified the predictive contribution of individual features. ResultsThe LightGBM demonstrated superior performance in predicting antimicrobial resistance for most tier 1 antibiotics among oxacillin-resistant S. aureus (ORSA) compared with all S. aureus and oxacillin-susceptible S. aureus (OSSA) in both databases. In DRIAMS, Multilayer Perceptron (MLP) was associated with excellent predictive performance, expressed as accuracy/AUROC/AUPR, for clindamycin (0.74/0.81/0.90), tetracycline (0.86/0.87/0.94), and trimethoprim-sulfamethoxazole (0.95/0.72/0.97). In the CS database, Ada and Light Gradient Boosting Machine (LightGBM) showed excellent performance for erythromycin (0.97/0.92/0.86) and tetracycline (0.68/0.79/0.86). Mass-to-charge ratio (m/z) features of 2411–2414 and 2429–2432 correlated with clindamycin resistance, whereas 5033–5036 was linked to erythromycin resistance in DRIAMS. In the CS database, overlapping features of 2423–2426, 4496–4499, and 3764–3767 simultaneously predicted the presence of mecA and oxacillin resistance. ConclusionThe predictive performance of antimicrobial resistance against S. aureus using MALDI-TOF MS depends on database characteristics and the ML algorithm selected. Specific and overlapping mass spectra features are excellent predictive markers for mecA and specific antimicrobial resistance.

Nasopharyngeal carriage, antimicrobial susceptibility patterns, and associated factors of Gram-positive bacteria among children attending the outpatient department at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia.

Gram-positive bacteria residing in the nasopharynx can lead to severe illnesses in children, such as otitis media, pneumonia, and meningitis. Despite the potential threat, there is a lack of comprehensive data regarding the carriage rates of these bacteria among children in outpatient departments in the study area. This study aimed to assess the nasopharyngeal carriage, antimicrobial resistance patterns, and associated factors of Gram-positive bacteria among children attending the outpatient department at the University of Gondar Comprehensive Specialized Hospital, Northwest Ethiopia. A hospital-based cross-sectional study was conducted from May 1, 2023, to August 30, 2023. A total of 424 nasopharyngeal swab samples were collected using sterile nasopharyngeal swabs, inoculated on Blood Agar and Mannitol Salt Agar plates, and identified through colony morphology, Gram stain, and biochemical tests. Antimicrobial susceptibility of the identified bacterial isolates was determined employing both the Kirby-Bauer and modified Kirby-Bauer methods. D-tests were conducted using clindamycin and erythromycin discs to detect inducible clindamycin resistance, while cefoxitin disc tests were utilized to ascertain methicillin resistance. Data entry was executed using Epi-Data version 4.6, and subsequent analysis was performed utilizing SPSS version 25. Bivariable and multivariable logistic regression analyses were employed to identify associated factors. An adjusted odds ratio at a 95% confidence interval with a P-value of < 0.05 was considered statistically significant. The overall nasopharyngeal carriage rate of Gram-positive bacteria was 296/424 (69.8%, 95% CI: 65.3-74.0). Staphylococcus aureus was the most prevalent 122/424 (28.8%), followed by Streptococcus pneumoniae 92/424 (21.7%). Methicillin resistance was observed in 19/122 (15.6%) of S. aureus and 3/60 (5%) of coagulase-negative staphylococcus (CoNS) species. Inducible clindamycin resistance was 10/122 (8.2%) in S. aureus and 4/53 (7.5%) in coagulase-negative staphylococcus species. Multidrug resistance was found in 146/296 (49.3%, 95% CI: 43.6-55.0) of the isolates. Associated factors with a bacterial carriage were large family size (AOR = 3.061, 95% CI: 1.595-5.874, P = 0.001), having siblings under five years old (AOR = 1.991, 95% CI: 1.196-3.313, P = 0.008), indoor cooking (AOR = 2.195, 95% CI: 1.275-3.778, P = 0.005), an illiterate mother (AOR = 3.639, 95% CI: 1.691-7.829, P = 0.001), and hospital visits (AOR = 2.690, 95% CI: 1.405-5.151, P = 0.003). The study found a high nasopharyngeal carriage of Gram-positive bacteria in outpatient children, including notable levels of methicillin-resistant S. aureus and multi-drug-resistant isolates. Clindamycin, rifampin, and erythromycin were the most effective antimicrobials for the tested isolates. Factors contributing to bacterial carriage include visits to healthcare facilities, larger family sizes, having younger siblings, maternal illiteracy, and indoor cooking. This emphasizes the need for methicillin-resistant S. aureus surveillance in pediatric outpatient settings and community health education, especially for children's guardians. Additionally, improving household ventilation by separating kitchens from sleeping areas and regular screening of younger siblings in healthcare environments were recommended to reduce bacterial transmission within family members. The study also called for studies with advanced procedures like minimum inhibitory concentration testing and molecular characterization to better comprehend the resistance patterns and genes in circulating bacteria.

Microbiology and Epidemiology of Orbital Cellulitis in Pediatric and Young Adult Patients.

Using data from the large and geographically diverse Military Health System (MHS) beneficiary population, we aimed to characterize and update the epidemiology and microbiology of pediatric orbital cellulitis given previous data are limited to small, single-center studies. Following institutional review board approval, we performed a retrospective analysis using the Military Health System admissions, microbiology, and pharmacy data between June 2009 and September 2019. Patients less than 22 years of age with radiological confirmation of orbital cellulitis were included. Demographic data, presence of sinusitis, advanced imaging reports, blood and wound culture results with antibiotic susceptibilities, and antibiotic prescriptions were collected. Descriptive statistics were used to summarize demographic characteristics. Imaging findings were grouped by Chandler's stage (CS), an imaging-based measure of the progressive severity of orbital involvement. A Cochran-Armitage trend test was used to evaluate the relationship between CS and likelihood of positive confirmatory culture. There was a male predominance (66.9%) and 55.5% of subjects had comorbid sinusitis. Of the 130 subjects included, 33.8% had one or more positive cultures, 30.8% had a positive wound culture, and 4.6% had a positive blood culture. The most identified organism was coagulase-negative staphylococci (23.3%), followed by Staphylococcus aureus (18.9%), Streptococcus intermedius (17.8%), and strict anaerobes as a group (13.3%). Gram-negative organisms were rare. Twenty-five percent of S. aureus were methicillin-resistant. Clindamycin resistance was identified in 9% of all S. aureus, 50% of coagulase-negative staphylococci, and 25% of S. intermedius. Clindamycin plus ceftriaxone was the most prescribed empiric antibiotic regimen (36.2%). Likelihood of a positive culture significantly increased with advancing CS. Orbital cellulitis occurs most frequently in males with sinusitis. Likelihood of positive wound culture is increased with a more advanced CS. Staphylococcus and Streptococcus spp. and anaerobes are the most identified pathogens in orbital cellulitis, while gram-negative organisms are rare. Empiric antibiotic selection should include an anti-methicillin-resistant S. aureus agent combined with a broad-spectrum beta-lactam and anaerobic coverage.

Tracking trends in the Top End: clindamycin and erythromycin resistance in Group A Streptococcus in the Northern Territory, 2012-2023.

This retrospective study reviewed the macrolide resistance rates of Group A Streptococcus (GAS) isolates in the Northern Territory from 2012 to 2023. Clindamycin and erythromycin resistance rates peaked in 2021, at 6.0% and 12.2% respectively, and then returned to near baseline at 1-2% in 2023. Increased resistance rates were identified in the Top End of Australia from mid-2020, followed 15 months later by high rates in central Australia in 2022. Factors associated with resistant isolates were living in a rural region and of age 18 years and older. Possible explanations include a transient clonal introduction of a resistant GAS strain to the Northern Territory from 2020 to 2022. Ongoing surveillance is required to monitor regional trends and identify temporal variations in resistant isolates.

Prevalence and genetic characteristics ofStaphylococcus aureus isolates from cellphones of medical students from Iran.

Although mobile phones as a rapid communication vehicle can lead to improved quality of healthcare, they can also facilitate the transmission of pathogens to patients. This current research focuses on genetic diversity, and genes involved in resistance and biofilm production of Staphylococcus aureus isolates from mobile phones of medical students. Antibiotic resistance profiling and polymerase chain reaction (PCR) amplification of antibiotic resistance and biofilm-related genes were investigated and statistically analyzed. Staphylococcal cassette chromosome mec (SCCmec) types were analyzed by multiplex PCR, and S. aureus protein A gene typing (spa typing) was done using PCR and sequencing. Sixty-four S. aureus isolates (16.8%) were obtained from 380 medical students' mobile phones who were working in hospitals. The findings showed that 71.9% of the isolates were MRSA and 78.1% were classified as MDR. All isolates exhibited sensitivity to vancomycin and linezolid. Overall, 7.8% of the isolates displayed an inducible clindamycin resistance phenotype, while 26.7% showed resistance to mupirocin. The results indicated that 68.8% of the isolates were biofilm producers, with 7 isolates (15.9%) classified as strong producers, 22 isolates (50%) as moderate producers, and 15 isolates (34.1%) as weak producers. The most prevalent type was CC8-MRSA III/t030 (18.7%), followed by CC8-MRSA III/t037 (12.5%), CC/ST22-MSSA/t790 (10.9%), CC1-MRSA IV-t114 (9.4%), CC1-MRSA IV-t127 (7.8%), CC8-MRSA V/t064 (7.8%), CC/ST15-MSSA-t360 (7.8%), CC30-MSSA/t021(6.3%), MRSA V-t355 (6.3%), CC8-MRSA III/t421 (4.7%), CC1-MRSA V-t267 (4.7%), and CC/ST15-MSSA-t084 (3.1%). The genetic diversity and prevalent multidrug resistance indicate that the resistance situation of S. aureus recovered from mobile phones in Tehran is severe, posing a potential threat to patients, the community, and healthcare settings.

Characteristics, Treatment, and Outcomes of Invasive Group A Streptococcal Infections

Background: Group A Streptococcus (GAS; Streptococcus pyogenes) is an important human pathogen that can cause life-threatening invasive disease, ranging from skin/soft tissue infections to infective endocarditis. In the fall of 2022, the Center for Disease Control &amp; Prevention (CDC) issued an alert due to a global increase in invasive GAS infections, particularly among children and adults with co-morbidities. An increase in invasive disease was observed at our five-hospital healthcare system in Southeast Michigan. The objective of this study was to describe characteristics of patients with invasive GAS and characterize treatment and outcomes of disease. Methods: This was a retrospective cross-sectional study of patients from June 2013 to August 2023 with positive blood cultures for GAS. Patients were identified using a data query for positive blood cultures for GAS through Microsoft SQL Server. Patients with age &lt; 1 8 years, polymicrobial bacteremia, incomplete data, or who were enrolled in hospice and/or died within 48-hours of admission were excluded. Collected variables included: demographics, infection characteristics (syndrome, duration of bacteremia), microbiological characteristics (antimicrobial susceptibility testing; AST), antimicrobial treatment (empiric and final, antitoxin therapy), and clinical outcomes (length of hospital stay [LOS], treatment-associated adverse events, 30-day mortality and infection-related readmission). Results: 250 patients were included (Table 1). More than half were male with median age of 57.5 years. Diabetes mellitus (38%) and chronic kidney disease (23%) were common comorbidities [Table 1]. Persons experiencing homelessness and persons who use injection drugs accounted for 9% and 13% of the cases, respectively. The most common infective syndrome accompanying bacteremia was cellulitis (57%). The majority of patients received vancomycin for empiric therapy (81%) and penicillin (38%) or cephalosporin (36%) for final regimen [Table 2]. A total of 79 GAS isolates (32%) were clindamycin resistant. Clindamycin was included in the empiric regimen of 20 (8%) patients, the final regimen in 44 (18%) of patients, and as antitoxin adjunct therapy in 135 (54%) of patients. A third (33%) of patients received no antitoxin. The average duration of antitoxin therapy was 3.6 days and antimicrobial therapy 19.9 days. The mean LOS was 11.4 days (Table 3). Thirty nine (16%) patients had treatment failure and 8 (3%) experienced C. difficile infection within 30 days of antimicrobial treatment. Thirty-day mortality was 11%; of these, 9% had in-hospital mortality. Conclusions: Invasive GAS infection confers significant morbidity and mortality, and ongoing research is needed to determine the best treatment regimens in the era of increasing clindamycin resistance.

Temporal trends of skin and soft tissue infections caused by methicillin-resistant Staphylococcus aureus in Gabon

BackgroundMethicillin-resistant Staphylococcus aureus (MRSA) is one of the leading causes of mortality due to bacterial antimicrobial resistance. While S. aureus is common in skin and soft tissue infections (SSTI) in Africa, data on MRSA rates are scarce and reports vary widely across the continent (5%-80%). In this study, we describe the proportion of MRSA causing SSTI in Lambaréné, Gabon, over an 11-year period.MethodsWe retrospectively analyzed data from 953 bacterial specimens collected from inpatients and outpatients with SSTI at the Albert Schweitzer Hospital, Lambaréné, Gabon, between 2009 and 2019. We determined temporal changes in the prevalence of MRSA and identified risk factors for SSTI with MRSA.Results68% of all specimens with bacterial growth yielded S. aureus (n = 499/731), of which 7% (36/497) with antimicrobial susceptibility testing were identified as MRSA. Age above 18 years, admission to the surgical ward, and deep-seated infections were significantly associated with MRSA as the causative agent. After an initial decline from 7% in 2009, there was a marked increase in the proportion of MRSA among all S. aureus from SSTI from 3 to 20% between 2012 and 2019. The resistance rate to erythromycin was significantly higher in MRSA than in methicillin-susceptible S. aureus (73% vs. 10%), and clindamycin resistance was detected exclusively in MRSA isolates (8%).ConclusionThe increasing proportion of MRSA causing SSTI over the 11-year period contrasts with many European countries where MRSA is on decline. Continuous surveillance of MRSA lineages in the hospital and community along with antibiotic stewardship programs could address the increasing trend of MRSA.

Antimicrobial Resistance Patterns of Outpatient Staphylococcus aureus Isolates

Oral non-β-lactam antibiotics are commonly used for empirical therapy of Staphylococcus aureus infections, especially in outpatient settings. However, little is known about potential geographic heterogeneity and temporal trends in the prevalence of S aureus resistance to non-β-lactams in the US. To characterize the spatiotemporal trends of resistance to non-β-lactam antibiotics among community-onset S aureus infections, including regional variation in resistance rates and geographical heterogeneity in multidrug resistance. This cross-sectional study used data from Veterans Health Administration clinics collected from adult outpatients with S aureus infection in the conterminous 48 states and Washington, DC, from January 1, 2010, to December 31, 2019. Data were analyzed from January to November 2023. Resistance to lincosamides (clindamycin), tetracyclines, sulfonamides (trimethoprim-sulfamethoxazole [TMP-SMX]), and macrolides. Spatiotemporal variation of S aureus resistance to these 4 classes of non-β-lactam antibiotics, stratified by methicillin-resistant S aureus (MRSA) and methicillin-sensitive S aureus (MSSA), and subdivided by regions of the US (Northeast, Midwest, South, and West). Trend tests and bivariate mapping were used to determine significant changes in resistant proportions over time and identify counties where rates of resistance to multiple non-β-lactams were high. A total of 382 149 S aureus isolates from 268 214 unique outpatients (mean [SD] age, 63.4 [14.8] years; 252 910 males [94.29%]) were analyzed. There was a decrease in the proportion of MRSA nationwide, from 53.6% in 2010 to 38.8% in 2019. Among MRSA isolates, we observed a significant increase in tetracycline resistance (from 3.6% in 2010 to 12.8% in 2019; P for trend < .001) and TMP-SMX resistance (from 2.6% in 2010 to 9.2% in 2019; P for trend < .001), modest and not significant increases in clindamycin resistance (from 24.2% in 2010 to 30.6% in 2019; P for trend = .34), and a significant decrease in macrolide resistance (from 73.5% in 2010 to 60.2% in 2019; P for trend < .001). Among MSSA isolates, significant upward trends in clindamycin, tetracyclines, and TMP-SMX resistance were observed. For example, tetracycline resistance increased from 3.7% in 2010 to 9.1% in 2019 (P for trend < .001). Regional stratification over time showed that the Northeast had slightly higher rates of clindamycin resistance but lower rates of tetracycline resistance, while the South had notably higher rates of resistance to tetracyclines and TMP-SMX, particularly among MRSA isolates. Bivariate mapping at the county scale did not indicate clear regional patterns of shared high levels of resistance to the 4 classes of antimicrobials studied. In this study of outpatient S aureus isolates, MRSA became less common over the 10-year period, and MRSA isolates were increasingly resistant to tetracyclines and TMP-SMX. Geographic analysis indicated no spatial overlap in counties with high rates of resistance to both tetracyclines and TMP-SMX. Examining the regional spatial variation of antibiotic resistance can inform empirical therapy recommendations and help to understand the evolution of S aureus antibiotic resistance mechanisms.

Rising clindamycin resistance in group A Streptococcus in an Irish healthcare institution.

Group A streptococcus (GAS) can cause serious invasive disease in humans with a high mortality rate. An increase in GAS infections was reported in Ireland in 2022, and this increase has been sustained in 2023 and is paralleled by similar trends in Europe. Rising antimicrobial resistance is a global problem and presents significant challenges to clinicians treating GAS infection. There was a reported increase in clindamycin resistance in GAS isolates in Ireland in 2022. We examined antimicrobial susceptibility patterns of GAS isolates in our institution in 2022. Although all GAS isolates included in our study were susceptible to penicillin, we noted a high clindamycin resistance rate of 28 % in our invasive GAS isolates. We also noted high tetracycline and erythromycin resistance, 43 and 30 %, respectively. Our results could have implications for empiric antimicrobial prescribing guidelines for skin and soft tissue infections, which often include clindamycin as it inhibits the production of many virulence factors associated with GAS. In addition, macrolides are often the first line recommended antibiotic for patients with anaphylaxis to penicillin. This study emphasises the importance of continuous surveillance and antimicrobial susceptibility testing of invasive and non-invasive isolates in order to monitor trends in increasing antimicrobial resistance.

Invasive group A streptococcal disease surveillance in Canada, 2021-2022.

Invasive group A streptococcal (iGAS, Streptococcus pyogenes) disease has been a nationally notifiable disease in Canada since 2000. This report summarizes the demographics, emm types, and antimicrobial resistance of iGAS isolates collected in Canada in 2021 and 2022. The Public Health Agency of Canada's National Microbiology Laboratory collaborates with provincial and territorial public health laboratories to conduct national surveillance of invasive S. pyogenes. Emm typing was performed using the Centers for Disease Control and Prevention emm sequencing protocol or extracted from whole-genome sequencing data. Antimicrobial susceptibilities were determined using Kirby-Bauer disk diffusion according to Clinical and Laboratory Standards Institute guidelines or predicted from whole-genome sequencing data based on the presence of resistance determinants. Overall, the incidence of iGAS disease in Canada was 5.56 cases per 100,000 population in 2021, decreasing from the peak of 8.6 cases per 100,000 population in 2018. A total of 2,630 iGAS isolates were collected during 2022, representing an increase from 2021 (n=2,179). In particular, there was a large increase in isolates collected from October to December 2022. The most predominant emm type overall in 2021 and 2022 was emm49, at 21.5% (n=468) and 16.9% (n=444), respectively, representing a significant increase in prevalence since 2018 (p<0.0001). The former most prevalent type, emm1, increased from 0.5% (n=10) in 2021 to 4.8% (n=125) in 2022; similarly, emm12 increased from 1.0% (n=22) in 2021 to 5.8% (n=151) in 2022. These two types together accounted for almost 25% of isolates collected in late 2022 (October to December). Antimicrobial resistance rates in 2021 and 2022 included: 14.9%/14.1% erythromycin resistance, 4.8%/3.0% clindamycin resistance, and <1% chloramphenicol resistance. The increase of iGAS isolates collected in Canada is an important public health concern. Continued surveillance of iGAS is critical to monitor expanding emm types and antimicrobial resistance patterns.