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Cystic fibrosis (CF) is characterized by early structural lung disease caused by pulmonary infections. The nasopharynx of infants is a major ecological reservoir of potential respiratory pathogens. To investigate the development of nasopharyngeal microbiota profiles in infants with CF compared with those of healthy control subjects during the first 6 months of life. We conducted a prospective cohort study, from the time of diagnosis onward, in which we collected questionnaires and 324 nasopharynx samples from 20 infants with CF and 45 age-matched healthy control subjects. Microbiota profiles were characterized by 16S ribosomal RNA-based sequencing. We observed significant differences in microbial community composition (P < 0.0002 by permutational multivariate analysis of variance) and development between groups. In infants with CF, early Staphylococcus aureus and, to a lesser extent, Corynebacterium spp. and Moraxella spp. dominance were followed by a switch to Streptococcus mitis predominance after 3 months of age. In control subjects, Moraxella spp. enrichment occurred throughout the first 6 months of life. In a multivariate analysis, S. aureus, S. mitis, Corynebacterium accolens, and bacilli were significantly more abundant in infants with CF, whereas Moraxella spp., Corynebacterium pseudodiphtericum and Corynebacterium propinquum and Haemophilus influenzae were significantly more abundant in control subjects, after correction for age, antibiotic use, and respiratory symptoms. Antibiotic use was independently associated with increased colonization of gram-negative bacteria such as Burkholderia spp. and members of the Enterobacteriaceae bacteria family and reduced colonization of potential beneficial commensals. From diagnosis onward, we observed distinct patterns of nasopharyngeal microbiota development in infants with CF under 6 months of age compared with control subjects and a marked effect of antibiotic therapy leading toward a gram-negative microbial composition.

We conducted patient chart reviews and whole-genome sequencing of wound specimens containing presumptive Corynebacterium ulcerans from Vancouver, British Columbia, Canada, during July 2019-July 2023. Sequencing confirmed 8/14 isolates were C. ramonii and identified 2 distinct clusters. Molecular methods should be used to clinically differentiate potential toxin-producing Corynebacterium spp.

Corynebacterium striatum is part of microbiota of skin and nasal mucosa of humans and has been increasingly reported as the etiologic agent of community-acquired and nosocomial diseases. Antimicrobial multidrug-resistant (MDR) C. striatum strains have been increasingly related to various nosocomial diseases and/or outbreaks worldwide, including fatal invasive infections in immunosuppressed and immunocompetent patients. Although cases of infections by C. striatum still neglected in some countries, the improvement of microbiological techniques and studies led to the increase of survival of patients with C. striatum nosocomial infections at different levels of magnitude. Biofilm formation on abiotic surfaces contributes for the persistence of virulent C. striatum and dissemination of antimicrobial resistance in hospital environment. Besides that, empirical antibiotic therapy can select multi-resistant strains and transfer intra and interspecies genes horizontally. In this study, a worldwide survey of C. striatum human infections and nosocomial outbreaks was accomplished by the analysis of clinical–epidemiological and microbiological features of reported cases from varied countries, during a 44-year period (1976–2020).

We report 2 human Corynebacterium silvaticum infections in Germany with axillary lymphadenitis and abscess formation; in 1 case the infection likely originated from a slaughtered wild boar. This recently described member of the diphtheria toxin gene-bearing C. diphtheriae species complex might be a new zoonotic pathogen.

We reviewed Corynebacterium spp. infection cases reported in South Africa during 2015-2023. We analyzed 84 isolates from 83 patients with C. diphtheriae, as well as 1 C. belfantii and 3 C. ulcerans isolates. Among C. diphtheriae cases, we observed respiratory diphtheria (26/83 patients [31%]), endocarditis (14/83 [17%]), cutaneous diphtheria (22/83 [27%]), nonspecific respiratory illnesses (5/83 [6%]), and asymptomatic carriage (16/83 [19%]). The median patient age was 19 (range 0-88) years. Diphtheria-tetanus-pertussis vaccination was incomplete for 26% (5/19) or unknown for 68% (13/19) of children 0-9 years of age. C. diphtheriae was intermediately resistant to penicillin (82/84 [98%] isolates; MIC 0.5 μg/mL) but susceptible to erythromycin (83/84 [99%] isolates; MIC 0.25 μg/mL). Eighteen unique sequence types were identified, corroborating C. diphtheriae heterogeneity. Toxin-producing strains were detected among cutaneous and respiratory diphtheria cases, indicating all forms of disease require monitoring and prompt public health action to curb transmission.

Corynebacterium ulcerans is an emerging zoonotic pathogen which causes diphtheria-like infections. Although C. ulcerans is found in multiple domestic and wild animal species, most human cases are linked with pets. Our ability to decipher cross-host species transmission dynamics and to understand the emergence of clinically relevant clones (e.g., diphtheria toxin-positive) is currently hampered by a limited knowledge of C. ulcerans strain diversity and genome evolution. Here, we explore the genomic population structure and evolution of C. ulcerans with 582 isolates from diverse hosts and geographical locations. A newly developed core genome genotyping scheme captures the population structure of C. ulcerans both at deep and shallow phylogenetic levels, uncovering its main sublineages and offering high strain subtyping resolution for epidemiological surveillance. Additionally, we reveal the diversity and distribution of the diphtheria toxin gene ( tox ), and those of its associated mobile elements. Considering the entire Corynebacterium diphtheriae Species Complex, we find four diphtheria toxin families, five tox -prophage families, and a novel tox -carrying genetic element. We show that some toxin families are shared across Corynebacterium species, revealing tox -prophage cross-species transfer. Our work enhances knowledge on the ecology and evolution of C. ulcerans and provides a genomic framework for tracking the dissemination of emerging sublineages. This study reveals prior undetected transmission events of Corynebacterium ulcerans , suggesting pets play an intermediary role between wildlife and humans. Two main sublineages were identified, showing high positivity rates for the diphtheria toxin.

To report the isolation and significance of C kroppenstedtii, features of patients with GLM, pathologic findings and mechanism, bacteriologic workup, and optimal treatment. Analysis of the cases with C kroppenstedtii at The University of Texas MD Anderson Cancer Center from 2016 to March 2024 for mechanistic insights. During a period of 8 years, isolates of C kroppenstedtii were obtained from 10 women and 7 men. All of the women, with an average age of 34 years (range, 18-61 years), presented with chronic or subacute mastitis, and were subsequently diagnosed with GLM. The men, with an average age of 66 years, had neoplastic diagnoses with the bacterium being commensal in 6 cases. Thus, C kroppenstedtii shows a predilection to infect the female breast (P < .001). Predisposing risks for GLM included childbirth in 8 women and nipple inversion in 2 women. Histopathology revealed xanthogranulomatous inflammation and Gram-positive bacilli within fat droplets or extracellularly. From GLM aspirates or tissue, the liquid culture media and/or anaerobic incubation yielded 9 of 10 isolates. Up to 14 tested strains were susceptible to vancomycin, linezolid, rifampin, and gentamicin. Nine women received extensive antimicrobial therapy.

Corynebacterium striatum ( C. striatum ) is a Gram-positive bacterium commonly colonizing the skin and mucosa in healthy individuals and hospitalized patients. Traditionally regarded as a contaminant, C. striatum is now increasingly recognized as a potential cause of clinical infections, especially after the coronavirus disease pandemic. It has emerged as a pathogen implicated in severe infections, including pneumonia, bacteremia, meningitis, artificial joint infections, abdominal infections, and endocarditis. C. striatum has been reported in lower respiratory tract infections, mostly as a conditioned pathogen in immunocompromised individuals, particularly in those with chronic structural lung diseases, such as chronic obstructive pulmonary disease, leading to severe pneumonia or exacerbation of the existing disease and high mortality. Additionally, C striatum has been implicated in the community-acquired pneumonia among immunocompetent individuals and nosocomial lung infections, with evidence of person-to-person transmission through caregivers. C. striatum may exhibit multidrug resistance. Vancomycin, alone or in combination, is currently considered the most effective treatment for C. striatum . This review highlights the epidemiological characteristics, drug resistance mechanisms, diagnostics approaches, and treatment options for C. striatum lower respiratory tract infections to enhance clinician awareness and improve patient management strategies.

Corynebacterium striatum is a nosocomial opportunistic pathogen increasingly associated with a wide range of human infections and is often resistant to several antibiotics. We investigated the susceptibility of 63 C . striatum isolated at the Farhat-Hached hospital, Sousse (Tunisia), during the period 2011–2014, to a panel of 16 compounds belonging to the main clinically relevant classes of antimicrobial agents. All strains were susceptible to vancomycin, linezolid, and daptomycin. Amikacin and gentamicin also showed good activity (MICs 90  = 1 and 2 mg/L, respectively). High rates of resistance to penicillin (82.5%), clindamycin (79.4%), cefotaxime (60.3%), erythromycin (47.6%), ciprofloxacin (36.5%), moxifloxacin (34.9%), and rifampicin (25.4%) were observed. Fifty-nine (93.7%) out of the 63 isolates showed resistance to at least one compound and 31 (49.2%) were multidrug-resistant. Twenty-nine resistance profiles were distinguished among the 59 resistant C . striatum . Most of the strains resistant to fluoroquinolones showed a double mutation leading to an amino acid change in positions 87 and 91 in the quinolone resistance-determining region of the gyrA gene. The 52 strains resistant to penicillin were positive for the gene bla , encoding a class A β-lactamase. Twenty-two PFGE patterns were identified among the 63 C . striatum , indicating that some clones have spread within the hospital.

Corynebacterium striatum is an emerging nosocomial pathogen. This is the first report showing the presence of three distinct multidrug resistant lineages of C. striatum among patients in a UK hospital. The presence of ErmX, Tet(W), Bla and AmpC proteins, and mutations in gyrA gene are associated with the resistance to clindamycin, doxycycline, penicillin and moxifloxacin, respectively. These strains are equipped with several corynebacterial virulence genes including two SpaDEF-type and a novel pilus gene cluster, which needs further molecular characterisation. This study highlights a need of developing an active surveillance strategy for routine monitoring and preventing potential cross-transmission among susceptible patients.