Search Results (616)

A Streptococcus suis strain isolated from the blood of a patient in Zhejiang Province, China, was analysed using whole-genome sequencing and tested for antimicrobial resistance. The isolated strain was identified as S. suis serotype 2, and classified to ST25 on multilocus sequence typing (MLST). The minimum core genome group of the strain was identified as Group 4, and multilocus variable-number tandem-repeat analysis (MLVA) assigned it as type 2, 4.4, 0, 9, 3, 2, 0, 0. An antimicrobial resistance analysis showed that the strain was resistant to clindamycin, tetracycline, azithromycin, and erythromycin but sensitive to 11 other antibiotics. In a genomic evolution analysis, this isolate clustered on the same branch as North American pig isolate, Chinese pig isolates from Tianjin, and Hubei pig isolates. Full article

Background/Objectives: Campylobacteriosis in human populations is an ongoing issue in both developed and developing countries. Poultry production is recognized as a reservoir for antimicrobial resistance and main source of human Campylobacter infection. Methods: In this study, sixty-five Campylobacter isolates were cultured from fecal samples collected from 17 flocks of broiler chickens in Alberta, Canada over two years (2015–2016). Susceptibility assays and PCR assays were performed to characterize resistance phenotypes and resistance genes. Conjugation assays were used to examine the mobility of AMR phenotypes. Results: Campylobacter jejuni was the predominant species recovered during both years of sampling. There were no Campylobacter coli isolates found in 2015; however, approximately 33% (8/24) of isolates collected in 2016 were Campylobacter coli. The two most frequent antimicrobial resistance patterns in C. jejuni collected in 2015 were tetracycline (39%) and azithromycin/clindamycin/erythromycin/telithromycin resistance (29%). One isolate collected in 2015 has resistance pattern ciprofloxacin/nalidixic acid/tetracycline. The tetO gene was detected in all tetracycline resistant isolates from 2015. The cmeB gene was detected in all species isolates with resistance to azithromycin/clindamycin/erythromycin/telithromycin, and from two isolates with tetracycline resistance. Alignment of the nucleotide sequences of the cmeB gene from C. jejuni isolates with different resistance patterns revealed several single nucleotide polymorphisms. A variety of multi-drug resistance patterns were observed through conjugation experiments. Conclusions: These data suggest that poultry production may serve as a potential reservoir for and source of transmission of multi-drug resistant Campylobacter jejuni and supports the need for continued surveillance. Full article

Antibiotic residues in poultry pose health and resistance risks, necessitating breed-specific WDTs. In this study, the residue elimination patterns of seven antibiotics in Taihang chicken tissues under free-range conditions were studied and the appropriate WDT was formulated. A total of 240 healthy Taihang chickens aged 100 days were randomly divided into 8 groups, each comprising 30 chickens. Chickens in groups 1 to 7 were administered oxytetracycline, chlortetracycline, erythromycin, tylosin, tylvalosin, lincomycin, and tiamulin, respectively. Regarding the administration method, we adopted the highest dose and maximum course of treatment recommended by the Veterinary Pharmacopoeia of the People’s Republic of China. Group 8 served as the control group. Muscle, sebum, liver, and kidney samples were collected at 4 h, 1 d, 2 d, 3 d, 5 d, 7 d, 10 d, 13 d, and 16 d after drug withdrawal. Our results demonstrated that the drug residues after drug withdrawal gradually decreased with the increase in drug withdrawal days, and the elimination rate in the early stage of drug withdrawal was significantly faster than that in the later stage. At 4 h after drug withdrawal, the drug residues in various tissues reached their highest values. In most cases, the drug concentrations in the kidney and liver were higher than those in the muscles and sebum; however, some drugs also exhibited concentration peaks in the sebum. On the first day of drug withdrawal, the amount of residues in various tissues decreased rapidly. In general, the elimination rate of various drugs in the muscles, liver, and kidneys is faster but slower in the sebum. Based on the WDT calculation software WT1.4, the recommended WDTs for oxytetracycline, chlortetracycline, erythromycin, tylosin, tylvalosin, lincomycin, and tiamulin chickens are 4 d, 5 d, 11 d, 8 d, 13 d, 13 d, and 7 d, respectively. These findings support food safety and industry development. Full article

Background/Objectives: European hedgehogs (Erinaceus europaeus) are present in areas where there is human activity; therefore, they can be a source of pathogens for other animals and humans. Methods: Eighteen hedgehog carcasses were collected and analyzed for Staphylococcus spp. Isolated strains were typed and analyzed for exfoliative toxins genes and the phenotypic and genotypic characteristics of antimicrobial resistance. Results: A total of 54 strains were isolated and typed as S. aureus, S. xylosus, S. sciuri, S. pseudintermedius, S. simulans, S. chromogenes, S. epidermidis, S. hyicus, and S. lentus. No strains had the eta and etb genes coding for exfoliative toxins. Overall, 39/54 (72.20%) isolates showed phenotypic resistance to at least one antimicrobial and 21/54 (38.80%) showed more than one resistance. The lowest efficacy was observed for erythromycin, with 40/54 (74.08%) strains classified as intermediate and 6/54 (11.11%) classified as resistant. Among the 29 isolates shown to be penicillin-resistant, 11 (37.93%) were oxacillin-resistant, with a minimum inhibitory concentration (MIC). Among the 54 staphylococcal strains, 2 (3.70%) were resistant to vancomycin, both with an MIC value equal to the maximum concentration of the antibiotic tested (256 μg/mL) and 2 (3.70%) had an intermediate resistance profile with an 8 μg/mL MIC value. No strains had the genes vanA and vanB. Two of the 29 (6.90%) penicillin-resistant strains had the blaZ gene; 8 (27.13%) strains had the mecA gene. Overall, 2/54 (3.70%) isolates were classified as extensively drug-resistant (XDR) and 9/54 (16.66%) were classified as multidrug-resistant (MDR). Conclusions: Hedgehogs can harbor antimicrobial-resistant staphylococci and can be sources of these bacteria for other animals and humans. They can also serve as bioindicators of the pathogens and antimicrobial-resistant bacteria circulating in a given habitat. Full article

Milk is frequently susceptible to contamination by potential pathogens, posing risks to both food safety and public health. Cheesemaking often relies on raw milk, where microbial communities—including Staphylococcus xylosus—can play a dual role: (i) contributing to fermentation and (ii) acting as opportunistic pathogens that can be often present in subclinical mastitis and be subjected to carry over in dairy products. In this study, Staphylococcus xylosus was isolated from raw bovine milk (preclinical mastitis) and identified via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (Biotyper scores: 1.87–2.19). Its susceptibility to erythromycin and to an essential oil blend composed of Myrtus communis, Salvia officinalis, and Cistus ladanifer was evaluated. The essential oil blend produced inhibition zones ranging from 9 mm to 13.3 mm, indicating moderate antibacterial activity. Further Minimum Inhibitory Concentration analysis revealed that Myrtus communis, Salvia officinalis, and the essential oil blend inhibited Staphylococcus xylosus growth at concentrations between 0.5 and 0.25 percent, while Cistus ladanifer required higher levels (1 to 0.5 percent). These findings suggest that selected essential oils—especially in combination—hold promise as complementary antimicrobial agents in food safety and antimicrobial resistance mitigation efforts. Full article

In this study, we isolated and identified bacteria from the feces of a diarrheal cynomolgus monkey. The results showed that the isolated strain was P. aeruginosa, named PA/CM-101101. Morphological observations indicated that when cultured on Luria–Bertani (LB) nutrient agar at 37 °C for 24 h, the strain formed smooth, slightly elevated colonies with neat and wavy edges. On acetamide agar at the same temperature and duration, the colonies appeared flat with irregular edges and a faint pink periphery, while the medium changed to rose-red; in LB broth at 37 °C for 24 h, the medium became turbid and yellowish-green. Gram staining revealed that it was negative and rod-shaped, without sporulation characteristics. The 16S rRNA gene sequence analysis showed that the sequence identity of the strain shared more than 98.4% similarity with 11 strains of P. aeruginosa from various sources in GenBank. The animal toxicity test showed that it had a strong pathogenic effect on mice. The results of drug sensitivity tests showed that strain PA/CM-101101 was sensitive to amikacin, azithromycin, cefoperazone, ceftazidime, ceftriaxone, ciprofloxacin, gentamicin, imipenem, levofloxacin, meropenem, norfloxacin, ofloxacin, and polymyxin B; however, it displayed resistance to ampicillin, cefadroxil, cefazolin, erythromycin, and vancomycin. The research findings provide valuable insights for diagnosis and treatment strategies for cynomolgus monkeys. It also provides a reference for molecular epidemiological studies. To our knowledge, this is the first time P. aeruginosa isolated from the diarrhea feces of cynomolgus monkey has been reported. Full article

Background and Aim: Pneumococcal pneumonia is a major cause of death globally, emphasizing the importance of vaccination, especially in low- and middle-income countries. In Iran, the 13-valent pneumococcal conjugate vaccine (PCV13) is available exclusively through private healthcare systems, resulting in a lack of studies on the prevalence of Streptococcus pneumoniae (S. pneumoniae) serotypes among vaccinated children. This research aimed to explore and compare the prevalence of nasopharyngeal pneumococcal carriage, serotype distribution, and antibiotic resistance patterns in healthy PCV13-vaccinated and -unvaccinated children. Methods: From August 2023 to November 2024, a multi-center, cross-sectional observational study was conducted in Tehran, Iran. This study included 204 nasopharyngeal samples collected from children aged from 18 to 59 months, involving both cases of children vaccinated with PCV13 and unvaccinated populations. S. pneumoniae was identified through a combination of culture methods and biochemical tests, confirmed by real-time PCR. Serotyping was achieved using cpsB sequencing, and the minimum inhibitory concentration method was employed to assess antibiotic resistance. Results: This study revealed similar S. pneumoniae carriage rates between PCV13-vaccinated and -unvaccinated Iranian children (20.6% vs. 21.6%). Serotypes 23F and 19F were prevalent in unvaccinated children, while 15B/15C was more prevalent in PCV13-vaccinated children. The included S. pneumoniae serotypes in PCV13 were detected more in the unvaccinated group. PCV13-vaccinated children exhibited no penicillin-resistant pneumococcal isolates, although four isolates were non-susceptible in unvaccinated children. Both groups showed substantial resistance to erythromycin and SXT. Previous respiratory infections, daycare attendance, residence in Tehran, and a history of antibiotic consumption increased the risk of pneumococcal carriage. Conclusions: PCV13 vaccination influences pneumococcal serotype distribution and antimicrobial susceptibility, although there was no significant difference regarding carriage rates between vaccinated and unvaccinated groups. These findings highlight the critical importance of vaccination in reducing invasive serotypes and antimicrobial resistance in children under five years old, emphasizing the importance of national PCV vaccination programs alongside continuous serotype surveillance. Full article

Maternal vaginal and rectal colonization by Streptococcus agalactiae (group B streptococcus, GBS) is the main risk factor for the development of newborn early-onset GBS disease (GBS-EOD). Much effort is in place for its prevention, including the development of vaccines. Currently, both a hexavalent glycoconjugate GBS vaccine against the most prevalent serotypes and a protein subunit vaccine have completed phase two clinical trials. GBS surveillance in both maternal carriage and neonatal disease is therefore important in establishing the coverage of the potential vaccines and in setting up the basis for pre- and post-marketing surveillance. A single-site study was conducted in the years 2020–2021 on the characteristics of 325 GBS strains (serotype distribution; identification of the alpha-like protein family member; and resistance to macrolides, tetracycline, and high-level gentamicin) isolated from the vaginal/rectal site in women in late pregnancy as well as in seven cases of GBS-EOD and one case of GBS-related stillbirth occurring in the same location and time period. The study indicated that the coverage of the developing vaccines was excellent (97.2% for the hexavalent glycoconjugate vaccine and 98.7% for the alpha-like protein subunit vaccine). However, the detection of the serotypes VI, VII, and IX—not covered by current vaccine formulations—accounting for 3.0% of isolates, as well as of negative alpha-like GBS strains from maternal carriage (1.2%), should be closely monitored over time. The high rates of GBS resistance to erythromycin (33.5%) and to clindamycin (29.5% in maternal carriage and 57.1% in GBS-EOD) was mostly due to the ever-increasing spread of the multidrug-resistant ST-17 subclone of serotype III. This finding, along with the newly emerging high-level gentamicin resistance in carriers (4.0%), mainly in serotype IV strains, poses a threat for the continued effectiveness of antibiotic therapy in invasive disease. Full article

Background: Antibiotic-resistant bacteria, especially Staphylococcus species, are a growing concern in healthcare settings and infections caused by multidrug-resistant strains are difficult to treat. Therefore, it is imperative to explore new treatment methods for these infections such as combinations of natural compounds with antibiotics. Methods: The main objective of this study was to investigate the antimicrobial activity of caffeic acid against staphylococcal strains. The viability of bacterial cells and half maximal inhibitory concentration (IC₅₀) for caffeic acid were also examined. The minimum inhibitory concentration (MIC) of the caffeic acid was determined using a serial microdilution method. To study the combined effect of caffeic acid and erythromycin, the fractional inhibitory concentrations (FICs) were determined. Results: Caffeic acid inhibited the growth of all the tested isolates, with MIC values ranging from 256 to 1024 µg/mL and reduced bacterial cell viability at concentrations corresponding to MIC values. Caffeic acid and erythromycin showed a synergistic effect when used together against three examined strains and had an additive effect against two isolates. However, their combination was indifferent against the seven remaining staphylococci tested. Conclusions: The results of our research demonstrate that caffeic acid has antimicrobial properties against the tested strains. Full article

Background: Campylobacter causes gastroenteritis worldwide with increasing antimicrobial resistance. Furazolidone (FZD) shows potential in resource-poor areas but needs further study. We aimed to assess the in vitro susceptibility of Campylobacter spp. to FZD, ciprofloxacin (CIP), and erythromycin (ERY) in a high-risk pediatric cohort and to evaluate the clinical relevance of resistance patterns using inhibitory quotient (IQ) pharmacodynamics. Methods: A two-phase prospective study (2012–2013, 2014–2015) was conducted at a tertiary pediatric hospital in Lima, Peru. Stool samples from children ≤24 months were cultured on selective media, with Campylobacter isolates identified via conventional bacteriological methods. Antimicrobial susceptibility was determined using Kirby–Bauer disk diffusion and regression-derived minimum inhibitory concentrations (MICs). IQ analysis correlated inhibition zones with therapeutic outcomes. Results: Among 194 Campylobacter isolates (C. jejuni: 28%; C. coli: 72%), resistance to CIP declined from 97.7% (2012–2013) to 83% (2014–2015), while ERY resistance rose from 2.3% to 9.4% (p= 0.002). No FZD resistance was observed, with mean inhibition zones of 52 ± 8 mm (2012–2013) and 43 ± 10.5 mm (2014–2015). MICs for FZD were predominantly <0.125 μg/mL, and all susceptible isolates demonstrated favorable IQ outcomes. Multidrug resistance (≥2 drugs) increased to 6.2% (2014–2015), though all MDR strains retained FZD susceptibility. CLSI and EUCAST breakpoints showed concordance for ERY (p = 0.724) but discordance for CIP (p = 0.022 vs. 0.008). Conclusions: FZD exhibits sustained in vitro efficacy against Campylobacter spp., even among MDR strains, contrasting with escalating fluoroquinolone and macrolide resistance. Full article

Campylobacter jejuni and Campylobacter coli are the two main campylobacter species that cause foodborne campylobacteriosis. Recent studies have reported that Campylobacter spp. are prone to developing resistance to antibiotics commonly used for their treatment, with many C. coli strains identified as multidrug-resistant. This study presents the results of the whole-genome sequencing analysis of the multidrug-resistant C. coli strain BCT3 isolated in Greece from a stool specimen of a pediatric patient presenting with diarrhea. The strain was isolated using selective culture media and, based on antimicrobial susceptibility tests, was found to be resistant to ciprofloxacin, tetracycline, erythromycin, azithromycin, clarithromycin, and doxycycline. To further characterize it, we performed whole-genome sequencing, which identified strain BCT3 as C. coli. Moreover, multilocus sequence typing assigned the BCT3 to the sequence type (ST) 872, belonging to clonal complex ST-828. The presence of multiple virulence genes revealed its pathogenic potential. The detection of antimicrobial resistance genes and mutated alleles was indicative of its resistance to fluoroquinolones, macrolides, and tetracyclines, supporting the observed phenotype. To our knowledge, this is the first reported clinical case of such a multidrug-resistant C. coli strain in Greece. Full article

Background and Objectives: The rising prevalence of drug-resistant organisms presents a significant challenge to healthcare, underscoring the importance of implementing effective antimicrobial stewardship programs. The success of these programs depends on access to accurate, evidence-based data reflecting local patterns of antibiotic resistance. This study aims to assess the antimicrobial susceptibility profiles of gram-positive bacteria isolated from pediatric patients in a tertiary care hospital in Egypt. Materials and Methods: We carried out a retrospective study over a five-year period, from January 2018 to December 2022, using microbiology laboratory records. Clinical samples included blood, urine, respiratory secretions, pus, wound, cerebrospinal fluid (CSF), and pleural fluid. The analysis focused on the resistance patterns of gram-positive pathogens identified through routine culture procedures. Antimicrobial susceptibility testing was performed using the Kirby–Bauer disc diffusion method, and vancomycin MIC was confirmed using the VITEK 2 system. Results: A total of 3223 gram-positive bacterial isolates were identified. Staphylococcus aureus, including 82.5% methicillin-resistant strains (MRSA), exhibited high resistance to erythromycin (47.3%) and gentamicin (low potency) (32.1%). Coagulase-negative staphylococci (CoNS) showed the highest erythromycin resistance (up to 88.3%), while Enterococcus spp. demonstrated declining susceptibility to vancomycin, levofloxacin, and erythromycin. Across all isolates, vancomycin and gentamicin (high potency) showed the highest overall susceptibility. Resistance to cotrimoxazole and doxycycline declined over the five-year period. Conclusions: While a decline in resistance was noted for some agents, persistent resistance to key antibiotics (particularly erythromycin and gentamicin) among MRSA and CoNS remains concerning. These findings underscore the importance of targeted antimicrobial stewardship interventions and continuous surveillance to inform empirical therapy in pediatric settings. Full article

Staphylococcus aureus is a significant bacterial pathogen responsible for a wide range of diseases in both humans and animals. This study aimed to investigate nucleotide sequence variations, gene expression patterns, and serum biomarkers, including acute phase proteins (APPs), hormonal fluctuations, and iron profile parameters in sheep affected by pneumonia. Additionally, the study focused on the isolation and characterization of S. aureus from pneumonic sheep, with particular emphasis on the prevalence of methicillin-resistant S. aureus (MRSA) strains. Blood samples were collected from both healthy and pneumonic sheep for gene expression and biochemical analyses, while nasal swabs from pneumonic sheep were used for bacterial isolation and identification. Out of 100 nasal swabs analyzed, 44% tested positive for Staphylococcus spp., and 61.4% of these were confirmed as S. aureus by PCR. The mecA gene, a key marker of methicillin resistance, was identified in 17 isolates (38.6% of the S. aureus-positive samples). MRSA isolates showed complete resistance to amoxicillin, cloxacillin, and erythromycin, and high resistance to penicillin, amoxicillin, and tetracycline; however, all MRSA strains remained fully susceptible to vancomycin. Gene expression analysis revealed that TLR2, CLEC4E, PTX3, CXCL8, and IL15RA were significantly upregulated (p < 0.05) in pneumonic ewes, while SOCS3 expression was markedly downregulated. Sequence analysis of immune-related genes revealed notable nucleotide differences between healthy and affected animals. Furthermore, the pneumonic group exhibited significantly elevated levels of APPs, cortisol, and growth hormone, along with reduced levels of insulin, T3, and T4. These findings underscore the zoonotic risk posed by MRSA and emphasize the need for robust surveillance and antibiotic stewardship to control its spread. The study also highlights the importance of molecular diagnostics in accurately identifying MRSA and elucidating resistance mechanisms, thereby facilitating targeted treatment and informed management strategies. Full article

The introduction of pneumococcal conjugate vaccination (PCV) into the Argentinian Childhood National Immunization Program in 2012 marked a significant milestone in public health. Our study aims to assess the impact of this intervention on pneumococcal meningitis cases, serotype distribution, and antimicrobial resistance among pediatric populations from 2013 to 2023. Specifically, we compared the early post-PCV period (2013–2014) to the late post-PCV period (2022–2023). A total of 333 pneumococcal isolates were analyzed between 2013 and 2023. Gold standard pneumococcal serotyping was performed to identify the serotypes associated with infection in children < 6 years in Argentina, and the agar dilution method was carried out to determine their profiles to antimicrobial agents. Our findings underscore the importance of PCV implementation, revealing notable shifts in pneumococcal epidemiology over the study period. The proportions of serotypes 1 (6.7% to 0.0%), 5 (5.6% to 0.0%), and 14 (7.8% to 1.8%) decreased, whereas the proportions of serotypes 10A (3.3% to 10.7%), 15B/C (2.2% to 10.7%), and 24B (0.0% to 8.9%) increased. The top five rated serotypes in the 2022–2023 period were serogroup 24 (21.4%), 10A (10.7%), 15B/C (10.7%), 23B (7.1%), and 12F (5.4%). Regarding antimicrobial resistance, we found that a total of 115/311 isolates (37%) were not suceptible to penicillin, and 2.9% were not suceptible to cefotaxime. Twenty-five percent of the isolates were microbial drug resistant, with resistance to penicillin, erythromycin, tetracycline/doxicycline, and/or cotrimoxazol. Among the PCV13 serotypes, 19A remained the most commonly associated with MDR. The non-PCV13 serotypes, particularly 24F, 24A, and 24B, were prevalent among MDR isolates. The observed trends demonstrate the need for the continued expansion of pneumococcal vaccination policies, including consideration for vaccines offering enhanced indirect protection, thereby extending benefits beyond the pediatric population to encompass adults as well. Such strategies are pivotal in reducing the burden of pneumococcal disease and safeguarding public health. Full article

The emergence of antimicrobial resistance (AMR) in Clostridium difficile (C. difficile), particularly to last-line antibiotics such as linezolid, represents a critical challenge in clinical settings. This study investigates the genomic epidemiology of linezolid-resistant C. difficile, focusing on the distribution and mutational patterns of the chloramphenicol–florfenicol resistance (cfr) gene and its association with multidrug resistance. We analyzed 514 clinical isolates (354 from NCBI Pathogen Detection, 160 from EnteroBase), revealing distinct prevalence patterns among cfr subtypes: cfr(C) was dominant (156/354 NCBI strains; 101/160 EnteroBase strains), whereas cfr(B) frequently harbored missense mutations (p.R247K, p.V294I, and less commonly p.A334T). The cfr(E) subtype was exclusively identified in ribotype 027 (RT027) strains. Notably, cfr(C) exhibited a strong association with RT017, correlating with a conserved 99 bp genomic deletion. Phylogenetic analysis linked cfr-carriage to predominant sequence types (ST1 in NCBI strains, ST37 in EnteroBase isolates). Furthermore, the co-occurrence of cfr with additional AMR genes conferred resistance to macrolides (erythromycin, azithromycin) and tetracyclines, indicating a convergent evolution toward multidrug resistance. These findings underscore the interplay between cfr mutations, hypervirulent ribotypes, and AMR dissemination, necessitating enhanced surveillance to mitigate the spread of resistant C. difficile lineages. Full article