Corynebacterium Pseudodiphtheriticum Research Articles

Antagonistic Effects of Corynebacterium pseudodiphtheriticum 090104 on Respiratory Pathogens.

In previous studies, it was demonstrated that Corynebacterium pseudodiphtheriticum 090104, isolated from the human nasopharynx, modulates respiratory immunity, improving protection against infections. Here, the antagonistic effect of the 090104 strain on respiratory pathogens, including Streptococcus pneumoniae, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, and Acinetobacter baumannii, was explored. In a series of in vitro studies, the capacity of C. pseudodiphtheriticum 090104, its bacterium-like particles, and its culture supernatants to coaggregate, inhibit the growth, and change the virulent phenotype of pathogenic bacteria was evaluated. The results showed that the 090104 strain was able to exert a bacteriostatic effect on K. pneumoniae and S. pneumoniae growth. In addition, C. pseudodiphtheriticum 090104 coaggregated, inhibited biofilm formation, and induced phenotypic changes in all the respiratory pathogens evaluated. In conclusion, this work demonstrated that, in addition to its beneficial effects exerted by host-microbe interactions, C. pseudodiphtheriticum 090104 can enhance protection against respiratory pathogens through its microbe-microbe interactions. The mechanisms involved in such interactions should be evaluated in future research.

Bacterium-like Particles from Corynebacterium pseudodiphtheriticum as Mucosal Adjuvant for the Development of Pneumococcal Vaccines.

Previously, it was shown that intranasally (i.n.) administered Corynebacterium pseudodiphtheriticum 090104 (Cp) or CP-derived bacterium-like particles (BLPs) improve the immunogenicity of the pneumococcal conjugate vaccine (PCV). This work aimed to deepen the characterization of the adjuvant properties of Cp and CP-derived BLPs for their use in the development of pneumococcal vaccines. The ability of Cp and CP-derived BLPs to improve both the humoral and cellular specific immune responses induced by i.n. administered polysaccharide-based commercial pneumococcal vaccine (Pneumovax 23®) and the chimeric recombinant PSPF (PsaA-Spr1875-PspA-FliC) protein was evaluated, as well as the protection against Streptococcus pneumoniae infection in infant mice. Additionally, whether the immunization protocols, including Cp and CP-derived BLPs, together with the pneumococcal vaccines can enhance the resistance to secondary pneumococcal pneumonia induced after inflammatory lung damage mediated by the activation of Toll-like receptor 3 (TLR3) was assessed. The results showed that both Cp and CP-derived BLPs increased the immunogenicity and protection induced by two pneumococcal vaccines administered through the nasal route. Of note, the nasal priming with the PSPF T-dependent antigen co-administered with Cp or CP-derived BLPs efficiently stimulated humoral and cellular immunity and increased the resistance to primary and secondary pneumococcal infections. The CP-derived BLPs presented a stronger effect than live bacteria. Given safety concerns associated with live bacterium administration, especially in high-risk populations, such as infants, the elderly, and immunocompromised patients, BLPs emerge as an attractive mucosal adjuvant to improve the host response to pneumococcal infections and to enhance the vaccines already in the market or in development.

The Respiratory Commensal Bacterium Corynebacterium pseudodiphtheriticum as a Mucosal Adjuvant for Nasal Vaccines.

Previously, we demonstrated that nasally administered Corynebacterium pseudodiphtheriticum 090104 (Cp) or its bacterium-like particles (BLPs) increase the resistance of mice against bacterial and viral respiratory pathogens by modulating the innate immunity. In this work, we evaluated the ability of Cp and BLPs to stimulate alveolar macrophages, and to enhance the humoral immune response induced by a commercial vaccine against Streptococcus pneumoniae. In the first set of experiments, Cp or the BLPs were incubated with primary cultures of murine alveolar macrophages and the phagocytic activity, and the production of cytokines was evaluated. The results revealed that Cp and BLPs were efficiently phagocyted by respiratory macrophages and that both treatments triggered the production of TNF-α, IFN-γ, IL-6, and IL-1β. In the second set of experiments, 3-week-old Swiss mice were intranasally immunized at days 0, 14, and 28 with the pneumococcal vaccine Prevenar®13 (PCV), Cp + PCV, or BLPs + PCV. On day 33, samples of bronco-alveolar lavages (BAL) and serum were collected for the study of specific antibodies. In addition, immunized mice were challenged with S. pneumoniae serotypes 6B or 19F on day 33 and sacrificed on day 35 (day 2 post-infection) to evaluate the resistance to the infection. Both Cp + PCV and BLPs + PCV groups had higher specific serum IgG and BAL IgA antibodies than the PCV control mice. In addition, the mice that were immunized with Cp + PCV or BLPs + PCV had lower lung and blood pneumococcal cell counts as well as lower levels of BAL albumin and LDH, indicating a reduced lung damage compared to the control mice. Improved levels of anti-pneumococcal antibodies were also detected in the serum and BAL samples after the challenges with the pathogens. The results demonstrated that C. pseudodiphtheriticum 090104 and its bacterium-like particles are capable of stimulating the respiratory innate immune system serving as adjuvants to potentiate the adaptive humoral immune response. Our study is a step forward in the positioning of this respiratory commensal bacterium as a promising mucosal adjuvant for vaccine formulations aimed at combating respiratory infectious diseases.

Respiratory Commensal Bacteria Increase Protection against Hypermucoviscous Carbapenem-Resistant Klebsiella pneumoniae ST25 Infection.

In a previous work, we demonstrated that nasally administered Corynebacterium pseudodiphtheriticum 090104 beneficially modulated the respiratory innate immune response and improved the protection against Respiratory Syncytial Virus and Streptococcus pneumoniae in mice. In this work, we aimed to evaluate whether the immunomodulatory 090104 strain was able to enhance the resistance against the respiratory infection induced by hypermucoviscous carbapenemase-producing (KPC-2) Klebsiella pneumoniae strains belonging to the sequence type (ST) 25. The nasal treatment of mice with C. pseudodiphtheriticum 090104 before the challenge with multiresistant K. pneumoniae ST25 strains significantly reduced lung bacterial cell counts and lung tissue damage. The protective effect of the 090104 strain was related to its ability to regulate the respiratory innate immune response triggered by K. pneumoniae challenge. C. pseudifteriticum 090104 differentially modulated the recruitment of leukocytes into the lung and the production of TNF-α, IFN-γ and IL-10 levels in the respiratory tract and serum. Our results make an advance in the positioning of C. pseudodiphtheriticum 090104 as a next-generation probiotic for the respiratory tract and encourage further research of this bacterium as a promising alternative to develop non-antibiotic therapeutical approaches to enhance the prevention of infections produced by microorganisms with multiple resistance to antimicrobials such as KPC-2-producing hypermucoviscous K. pneumoniae strains belonging to ST25.

Corynebacterium pseudodiphtheriticum as a Pathogen in Bacterial Co-Infection in COVID-19 Patients on Mechanical Ventilation.

Many studies have been conducted on ventilator-associated complications (VACs) in patients with coronavirus 2019 (COVID-19). However, in these studies, the causative organisms were similar, and there were no reports on VAC corresponding with Corynebacteria. Coryneforms are frequently cultured in cases of polymicrobial infections and are usually considered contaminants in respiratory specimens. However, Corynebacterium pseudodiphtheriticum or C. striatum is known to be a pathogen in lower respiratory tract infections. We report three cases of VAC, probably due to C. pseudodiphtheriticum, in patients with COVID-19. If purulent lower respiratory tract specimens showed coryneform predominantly upon Gram staining, empirical therapy should be started. Furthermore, species identification and drug susceptibility testing should be performed.

Upper Respiratory Tract Microbiome of Australian Aboriginal and Torres Strait Islander Children in Ear and Nose Health and Disease.

ABSTRACTThe objective of this study was to examine the nasal microbiota in relation to otitis media (OM) status and nose health in Indigenous Australian children. Children 2 to 7 years of age were recruited from two northern Australian (Queensland) communities. Clinical histories were obtained through parent interviews and reviews of the medical records. Nasal cavity swab samples were obtained, and the children’s ears, nose, and throat were examined. DNA was extracted and analyzed by 16S rRNA amplicon next-generation sequencing of the V3/V4 region, in combination with previously generated culture data. A total of 103 children were recruited (mean age, 4.7 years); 17 (16.8%) were healthy, i.e., normal examination results and no history of OM. The nasal microbiota differed significantly in relation to OM status and nose health. Children with historical OM had greater relative abundance of Moraxella, compared to healthy children, despite both having healthy ears at the time of swabbing. Children with healthy noses had greater relative abundance of Staphylococcus aureus, compared to those with rhinorrhea. Dolosigranulum was correlated with Corynebacterium in healthy children. Haemophilus and Streptococcus were correlated across phenotypes. Ornithobacterium was absent or was present with low relative abundance in healthy children and clustered around otopathogens. It correlated with Helcococcus and Dichelobacter. Dolosigranulum and Corynebacterium form a synergism that promotes upper respiratory tract (URT)/ear health in Indigenous Australian children. Ornithobacterium likely represents “Candidatus Ornithobacterium hominis” and in this population is correlated with a novel bacterium that appears to be related to poor URT/ear health.IMPORTANCE Recurring and chronic infections of the ear (OM) are disproportionately prevalent in disadvantaged communities across the globe and, in particular, within Indigenous communities. Despite numerous intervention strategies, OM persists as a major health issue and is the leading cause of preventable hearing loss. In disadvantaged communities, this hearing loss is associated with negative educational and social development outcomes, and consequently, poorer employment prospects and increased contact with the justice system in adulthood. Thus, a better understanding of the microbial ecology is needed in order to identify new targets to treat, as well as to prevent the infections. This study used a powerful combination of 16S rRNA gene sequencing and extended culturomics to show that Dolosigranulum pigrum, a bacterium previously identified as a candidate protective species, may require cocolonization with Corynebacterium pseudodiphtheriticum in order to prevent OM. Additionally, emerging and potentially novel pathogens and bacteria were identified.

16S rDNA PCR for the aetiological diagnosis of culture-negative infective endocarditis

Culture-negative infective endocarditis (IE) accounts for 7-31% of all cases. Metagenomics has contributed to improving the aetiological diagnosis of IE patients undergoing valve surgery. We assessed the impact of 16S ribosomal DNA gene polymerase chain reaction (16S rDNA PCR) in the aetiological diagnosis of culture-negative IE. Between January 2016 and January 2020, clinical data from culture-negative IE patients were reviewed retrospectively. Identification of bacteria was performed using 16S rDNA PCR in heart valve specimens. 36 out of 313 patients (12%) with culture-negative IE had their valve tissue specimens submitted for 16S rDNA PCR. 16S rDNA PCR detected and identified bacterial nucleic acid in heart valve tissue significantly more frequently compared to valve culture alone 25(70%) vs 5(12%); p < 0.05. Mean age was 57years (SD 18) and 80% were male. Native and aortic valve were involved in 76% and 52% of cases, respectively. Streptococcus spp. (n 15) were the most commonly detected organisms, followed by bacteria of the HACEK group (Haemophilus parainfluenzae 2, Aggregatibacter actinomycetemcomitans 1), nutritionally variant streptococci (Abiotrophia defectiva 2), and one each of Staphylococcus aureus, Corynebacterium pseudodiphtheriticum, Helcococcus kunzii, Neisseria gonorrhoeae, Tropheryma whipplei. 16S rDNA PCR may be a useful diagnostic tool for the identification of the causative organism in culture-negative IE. Efforts towards a shorter turnaround time for results should be consider and further studies assessing the clinical impact of this technique in culture-negative IE are needed.

Study of Normal Flora in the Pharynx of Healthy Children.

To improve our current understanding of normal flora in children, we investigated bacterial isolates from the pharynx and nasopharynx of 173 and 233 healthy children, respectively. The bacterial isolation rates were compared among three age groups: infants (<1 year), toddlers (1-5 years), and school-aged children (6-15 years). Gram-positive cocci were the predominant bacteria in the pharynx (Streptococcus mitis/oralis, 87.3%; Streptococcus salivarius, 54.3%; Rothia mucilaginosa, 41.6%; Staphylococcus aureus, 39.3%). Among infants, S. salivarius and Neisseria subflava, which are related to the development of teeth, were significantly lower than in the other age groups (P <0.0001, S. salivarius; P <0.01, N. subflava). With the exception of Corynebacterium pseudodiphtheriticum (44.2%, gram-positive rods), gram-negative rods largely predominated the nasopharynx (Moraxella catarrhalis, 32.1%; Moraxella nonliquefaciens, 28.3%). Among toddlers, M. catarrhalis and Streptococcus pneumoniae, which are the most common pathogens in acute otitis media, were significantly higher than in the infant group (P <0.05). Among the bacterial species implicated in pediatric respiratory infections, Streptococcus pyogenes was isolated in 3.5% of the pharyngeal samples. S. pneumoniae and Haemophilus influenzae were isolated in 22.3% and 17.2% of the nasopharyngeal samples, respectively. In conclusion, the normal flora of the respiratory tract differs not only by the sampling site but also by the age group.

Upper Respiratory Microbiota in Relation to Ear and Nose Health Among Australian Aboriginal and Torres Strait Islander Children.

We explored the nasal microbiota in Indigenous Australian children in relation to ear and nasal health. In total, 103 Indigenous Australian children aged 2-7 years (mean 4.7 years) were recruited from 2 Queensland communities. Children's ears, nose, and throats were examined and upper respiratory tract (URT) swabs collected. Clinical histories were obtained from parents/medical records. URT microbiota were characterized using culturomics with Matrix assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF MS) identification. Real-time PCR was used to quantify otopathogen (Haemophilus influenzae, Streptococcus pneumoniae, and Moraxella catarrhalis) loads and detect respiratory viruses. Data were analyzed using beta diversity measures, regression modeling, and a correlation network analysis. Children with historical/current otitis media (OM) or URT infection (URTI) had higher nasal otopathogen detection and loads and rhinovirus detection compared with healthy children (all P < .04). Children with purulent rhinorrhea had higher nasal otopathogen detection and loads and rhinovirus detection (P < .04) compared with healthy children. High otopathogen loads were correlated in children with historical/current OM or URTI, whereas Corynebacterium pseudodiphtheriticum and Dolosigranulum pigrum were correlated in healthy children. Corynebacterium pseudodiphtheriticum and D. pigrum are associated with URT and ear health. The importance of the main otopathogens in URT disease/OM was confirmed, and their role relates to co-colonization and high otopathogens loads.

Investigation of a Large Diphtheria Outbreak and Cocirculation of Corynebacterium pseudodiphtheriticum Among Forcibly Displaced Myanmar Nationals, 2017-2019.

Diphtheria, a life-threatening respiratory disease, is caused mainly by toxin-producing strains of Corynebacterium diphtheriae, while nontoxigenic corynebacteria (eg, Corynebacterium pseudodiphtheriticum) rarely causes diphtheria-like illness. Recently, global diphtheria outbreaks have resulted from breakdown of health care infrastructures, particularly in countries experiencing political conflict. This report summarizes a laboratory and epidemiological investigation of a diphtheria outbreak among forcibly displaced Myanmar nationals in Bangladesh. Specimens and clinical information were collected from patients presenting at diphtheria treatment centers. Swabs were tested for toxin gene (tox)-bearing C. diphtheriae by real-time polymerase chain reaction (RT-PCR) and culture. The isolation of another Corynebacterium species prompted further laboratory investigation. Among 382 patients, 153 (40%) tested tox positive for C. diphtheriae by RT-PCR; 31 (20%) PCR-positive swabs were culture confirmed. RT-PCR revealed 78% (298/382) of patients tested positive for C. pseudodiphtheriticum. Of patients positive for only C. diphtheriae, 63% (17/27) had severe disease compared to 55% (69/126) positive for both Corynebacterium species, and 38% (66/172) for only C. pseudodiphtheriticum. We report confirmation of a diphtheria outbreak and identification of a cocirculating Corynebacterium species. The high proportion of C. pseudodiphtheriticum codetection may explain why many suspected patients testing negative for C. diphtheriae presented with diphtheria-like symptoms.

Corynebacterium Species of the Conjunctiva and Nose: Dominant Species and Species-Related Differences of Antibiotic Susceptibility Profiles.

Nondiphtherial Corynebacterium species are normal residents of human skin and mucosa, including the conjunctiva and nose, but can cause conjunctivitis and keratitis. Recently, resistance against various classes of antibiotics has been reported in Corynebacterium. The present study investigated the type of species and antibiotic susceptibilities of the conjunctival and nasal Corynebacterium species. This study examined 183 strains of Corynebacterium species that were isolated from patients undergoing preoperative examinations for cataract surgery. Species were identified by RNA polymerase β-subunit-encoding gene (rpoB) sequencing. Antibiotic susceptibility tests were performed by the microdilution method according to the Clinical and Laboratory Standards Institute standard method M45. Corynebacterium macginleyi was the most predominant species (84%; 46 of 55) in the conjunctiva. The 2 major species in the nasal cavity were Corynebacterium accolens and Corynebacterium propinquum (44% and 31%, respectively), followed by Corynebacterium pseudodiphtheriticum (8%), Corynebacterium jeikeium (7%), and C. macginleyi (3%). In contrast to other nasal Corynebacterium species, only C. macginleyi showed a high susceptibility to macrolides. However, among nonconjunctival Corynebacterium species, C. propinquum, was unique in having a high resistance rate to levofloxacin (29%), comparable with that observed in C. macginleyi (36%). Penicillin G and tobramycin showed good susceptibility in almost all strains. Drug resistance against fluoroquinolones and macrolides was observed in Corynebacterium species, with the antibiotic susceptibility profiles correlating with differences of the species and niche. Nasal and conjunctival Corynebacterium profiles of drug resistance suggest habitat segregation strictly at the species level.

The Ability of Respiratory Commensal Bacteria to Beneficially Modulate the Lung Innate Immune Response Is a Strain Dependent Characteristic.

We investigated whether the ability of commensal respiratory bacteria to modulate the innate immune response against bacterial and viral pathogens was a shared or strain-specific characteristic. Bacterial strains belonging to the Corynebacterium pseudodiphtheriticum and Dolosigranulum pigrum species were compared by studying their influence in the Toll-like receptor (TLR)-2- and TLR3-triggered immune responses in the respiratory tract, as well as in the resistance to Respiratory Syncytial Virus (RSV) and Streptococcus pneumoniae infections. We demonstrated that nasally administered C. pseudodiphteriticum 090104 or D. pigrum 040417 were able to modulate respiratory immunity and increase the resistance against pathogens, while other strains of the same species did not influence the respiratory immune responses, demonstrating a clear strain-dependent immunomodulatory effect of respiratory commensal bacteria. We also reported here that bacterium-like particles (BLP) and cell walls derived from immunomodulatory respiratory commensal bacteria are an interesting alternative for the modulation of the respiratory immune system. Our study is a step forward in the positioning of certain strains of respiratory commensal bacteria as next-generation probiotics for the respiratory tract.

Infection and colonization by Corynebacterium pseudodiphtheriticum: a 9-year observational study in a university central hospital.

Despite constituting part of the human commensal flora, Corynebacterium pseudodiphtheriticum has been recognized as a potentially infectious agent, most frequently in immunocompromised patients or individuals with other morbidity factors, but significant association to comorbid states remains unproven. This study's purpose was to assess clinical significance, risk factors for infection and antimicrobial susceptibility of C. pseudodiphtheriticum isolates. A retrospective observational study was conducted. Relevance of isolation was determined by clinical, laboratory, and imaging criteria. Forty-nine isolates occurred in 47 episodes. Colonization was assumed in 12% and infection in 78%, of which 51% were nosocomial. Patients with infection were older, with male predominance; both age and gender were statistically significant (p < 0.05) between infection and colonization groups. Although dyslipidemia (58%), arterial hypertension (58%), invasive procedures (56%), and chronic lung disease (50%) were prevalent in the infection group, no comorbidity was a significant risk factor for infection compared with colonization. Charlson comorbidity index showed no statistically difference between groups. Mortality rate was 14% in infection. Respiratory samples were the main isolation product; all tested strains were susceptible to amoxicillin/clavulanate and vancomycin. Resistant strains were observed for clindamycin (77%) and erythromycin (48%). C. pseudodiphtheriticum isolation was associated with infection in most cases. Despite the high prevalence of comorbidities and invasive procedures, no factors other than age and gender were significantly associated with infection. Although C. pseudodiphtheriticum may constitute a contaminant or colonizer in clinical samples, positive cultures in patients with signs and symptoms consistent with infection should not be neglected.

Antimicrobial Susceptibility Testing for Corynebacterium Species Isolated from Clinical Samples in Romania

Antimicrobial resistance is one of the most important public health issues. Besides classical multidrug resistance species associated with medical care involved in superficial or invasive infections, there are strains less commonly associated with hospital or outpatient setting’s infections. Non-diphtheria Corynebacterium spp. could produce infections in patients with or without immune-compromised status. The aim of our study was to determine the susceptibility to antimicrobial agents to Corynebacterium spp. from clinical samples collected from Romanian hospitalized individuals and outpatients. Twenty Corynebacterium strains were isolated and identified as Corynebacterium striatum (n = 7), Corynebacterium amycolatum (n = 7), C. urealyticum (n = 3), Corynebacterium afermentans (n = 2), and Corynebacterium pseudodiphtheriticum (n = 1). All isolates have been tested for antibiotic susceptibility by standardized disc diffusion method and minimal inhibitory concentration (MIC) tests. Seventeen isolates demonstrated multidrug resistance phenotypes. The molecular support responsible for high resistance to quinolones for ten of these strains was determined by the detection of point mutation in the gene sequence gyrA.

Use of Dipstick Assay and Rapid PCR-DNA Analysis of Nasal Secretions for Diagnosis of Bacterial Sinusitis in Children With Chronic Cough.

BackgroundChronic cough in children is a diagnostic challenge.ObjectiveTo discover the utility of nasal dipsticks and polymerase chain reaction (PCR)-DNA analysis in differentiating bacterial sinusitis from other causes of chronic cough and identifying pathogens from the nasal cavity.MethodWe recruited 22 patients under 15 years of age with cough lasting longer than 4 weeks (group 1), 7 controls with allergic rhinitis (group 2), and 10 controls without respiratory symptoms (group 3). Based on symptoms, the results of nasal secretion assays, and nasal endoscopy, a diagnosis of clinical bacterial sinusitis was made. We identified potential pathogens by quantitative PCR of nasal secretions.ResultsGroup 1A (cough with clinical bacterial sinusitis n = 10): Eight (80%) patients had bacterial sinusitis associated with dominant potential pathogenic bacteria (PPB): Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. Group 1B (cough without clinical bacterial sinusitis n = 12): None had dominant PPB. Group 2 (allergic rhinitis n = 7): None had dominant PPB. Group 3 (asymptomatic n = 10): None had dominant PPB. Twenty to 57% of all groups were colonized with Staphylococcus aureus. Fifty to 70% were colonized with Staphylococcus epidermidis, Corynebacterium pseudodiphtheriticum, and Dolosigranulum pigrum.ConclusionIn children with chronic cough, clinicians can utilize a simple and inexpensive nasal secretion dipstick assay for rapid diagnosis of sinusitis and identify PPB by DNA-PCR test for specific antibiotic treatment.

FORMULATION DEVELOPMENT AND EVALUATION OF pH TRIGGERED IN SITU OPHTHALMIC GEL OF BESIFLOXACIN HYDROCHLORIDE

The aim of the present work was to formulation and evaluation of pH Triggered in-situ Ophthalmic Gel of Besifloxacin Hydrochloride to overcome the drawbacks obtained by conventional eye drop. There are two independent variables were used i.e. Carbopol 934 and HPMC K100. Carbopol 934 were used as gelling agent and HPMC K100 were used as bioadhesive polymer. Besifloxacin Hydrochloride shows activity against a wide range of Gram-positive and negative ocular pathogens: examples are Corynebacterium pseudodiphtheriticum, Moraxella lacunata, Staphylococcus aureus, Staphylococcus epidermidis, Streptococcus pneumoniae and Streptococcus salivarius. The in situ gelling system involves sol-to-gel transition in the cul-de-sac upon instillation to avoid pre corneal elimination. The formulations were prepared by 32 factorial design. The prepared formulations were evaluated for clarity, pH, viscosity, Bioadhesive strength of gel, gel strength gel, Drug Content, In-vitro Drug Release Study, Antibacterial Activity, Isotonicity Evaluation, HET-CAM Test and stability studies. The drug content was in the range of 97-99.57 %. Formulation F5 selected as optimized on the basis of evaluation. It shows highest drug release upto 8hrs. It shows good antibiotic activity against Staphylococcus aureus. The optimized formulation was isotonic with blood cells. It passes sterility test. The optimized formulation passes the ocular irritancy test i.e. HET-CAM Test. The formulation kept for the stability study for 3 months. Short term stability study indicates that room temperature 400±20 was appropriate storage condition for formulations.&#x0D; Keywords: pH Triggered, bioadhesive polymer, Carbopol 934, HPMC K100, HET-CAM Test, Antibacterial Activity.

The antibiotic sensitivity of Corynebacterium diphtheriaе gravis tox+ in composition of mixed biofilms.

The purpose of study is to determine sensibility of strains of C. diphtheriae gravis tox+ in the composition of mixed biofilms to antibacterial medications. The object of study was strains of Corynebacterium diphtheriae gravis tox+ № 665, Corynebacterium pseudodiphtheriticum (poly-resistant), Corynebacterium pseudodiphtheriticum (antibiotic-resistant). Two mixed biofilms (120- and 720-hours) of strain of Corynebacterium diphtheriae gravis tox+ № 665 with strains of Corynebacterium pseudodiphtheriticum (poly-resistant), Corynebacterium pseudodiphtheriticum (antibiotic-resistant) were formed. The sensibility of typical and biofilm cultures of Corynebacteria to antibiotic medications was established using technique of serial dilution in fluid growth medium on the basis of MPC (mg/l). The typical culture of museum strain C. diphtheriae gravis tox+ № 665, modeling mixed biofilms had a sensitivity to all used antibacterial medications. The analysis of antibiotic resistance of strain of C. diphtheriae gravis tox+ № 665 in content of biofilm with strain С. pseudodiphtheriticum, poly-resistant to four antibacterial medications (cefazolin, kanamycin, azithromycin, ciprofloxacin, IPC from 1.25±0,00 to >5±0,00 mkg/ml) set reduction (p≤0,05) sensitivity 120-hour biofilm cultures of this strain to cefazolin, azithromycin, ciprofloxacin (MIC of 0, 234 and up to ±0,11>5±0,00 ug / ml) established decreasing (p≤0,05) of sensitivity of 120-hours biofilm culture of this strain to cefazolin, azithromycin, ciprofloxacin (MIC from 0, 234±0,11 to >5±0,00 mkg/ml) and 720-hours culture - to all mentioned medications (MIC from 0,312±0,00 to >5±0,00 mkg/ml). The comparison of antibiotics resistance of biofilm cultures of strain C. diphtheriae gravis tox+ № 665 established that indices of MIC of most of antibacterial medications and especially to those that poly-resistant and forming biofilm strain С. рseudodiphtheriticum was resistant, were higher as related to biofilm cultures of diphtheritic bacteria separated from biofilm with antibiotic resistant strain С. рseudodiphtheriticum. The trend was established related to decreasing of antibiotic sensitivity of Corynebacteria at cultivation in content of mixed biofilms with representatives of opportunistic Corynebacteria having polyresistance to antibacterial medications.

A Rare Case of Corynebacterium Endocarditis

A 26-year-old gentleman presented with a 1-month history of fevers, malaise and weight loss. He was born in China and had moved to Australia during his childhood. He was appropriately vaccinated. There was no history of recent dental procedures or illicit drug use. On examination, the temperature was 39 °C. Heart rate, blood pressure and oxygen saturations were normal. There was a pan-systolic murmur over the apex. There were small, non-tender, erythematous macules over both palms consistent with Janeway lesions. Neurological examination was unremarkable. Blood tests revealed raised inflammatory markers (C-reactive protein 87 mg/L). Four separate sets of blood cultures at admission isolated Corynebacterium pseudodiphtheriticum, sensitive to penicillin. Urgent transthoracic echocardiography revealed a large vegetation (11 × 9 mm) attached to the anterior mitral leaflet with associated moderate-severe regurgitation. Left ventricular function was preserved. The patient was commenced on empirical therapy for endocarditis, subsequently rationalised to intravenous benzylpenicillin. Embolic workup revealed multiple cerebral lesions suspicious for mycotic aneurysms and a small subacute infarction in the right frontal lobe. He underwent mechanical mitral valve replacement after 2 weeks of intravenous antibiotic therapy. Valve tissue and subsequent blood cultures were negative and the patient was discharged home following a 6-week admission.

Respiratory Commensal Bacteria Corynebacterium pseudodiphtheriticum Improves Resistance of Infant Mice to Respiratory Syncytial Virus and Streptococcus pneumoniae Superinfection.

Corynebacterium pseudodiphtheriticum is a Gram-positive bacterium found as a member of the normal microbiota of the upper respiratory tract. It was suggested that C. pseudodiphtheriticum may be potentially used as a next-generation probiotic for nasal application, although no deep studies were performed in this regard. We hypothesized that human isolate C. pseudodiphtheriticum strain 090104 is able to modulate the respiratory innate immune response and beneficially influence the resistance to viral and bacterial infections. Therefore, in the present study we investigated how the exposure of infant mice to nasal priming with viable or non-viable C. pseudodiphtheriticum 090104 influences the respiratory innate immune response triggered by Toll-like receptor (TLR)-3 activation, the susceptibility to primary Respiratory Synsytial Virus (RSV) infection, and the resistance to secondary Streptococcus pneumoniae pneumonia. We demonstrated that the nasal priming with viable C. pseudodiphtheriticum 090104 differentially modulated TLR3-mediated innate antiviral immune response in the respiratory tract of infant mice, improving their resistance to primary RSV infection, and secondary pneumococcal pneumonia. In association with the protection against RSV-pneumococcal superinfection, we found that viable C. pseudodiphtheriticum improved lung CD3+CD4+IFN-γ+, and CD3+CD4+IL-10+ T cells as well as CD11c+SiglecF+IFN-β+ alveolar macrophages. Of interest, non-viable bacteria did not have the same protective effect, suggesting that C. pseudodiphtheriticum colonization is needed for achieving its protective effect. In conclusion, we present evidence that nasal application of viable C. pseudodiphtheriticum could be thought as an alternative to boost defenses against RSV and secondary pneumococcal pneumonia, which should be further studied and validated in clinical trials. Due to the absence of a long-lasting immunity, re-infection with RSV throughout life is common. Thus, a possible perspective use could be a seasonal application of a nasal probiotic spray to boost respiratory innate immunity in immunocompetent subjects.

Diphtheroids-Important Nosocomial Pathogens.

Diphtheroids are defined as aerobic, non-sporulating, pleomorphic Gram-positive bacilli which are more uniformly stained than Corynebacterium diphtheriae, lack the metachromatic granules and are arranged in a palisade manner. They are usually commensals of the skin and mucous membranes. They differ from C.diphtheriae in biochemical rea-ctions as well as in toxin production. Since, they are usually found as commensals on the skin, they are often considered as mere contaminants when isolated from clinical samples. However, there are increasing reports of these organisms being associated with various infections. Hence, we felt the need to study the common species associated with infections and know the properties of these organisms which are otherwise considered as mere laboratory contaminants. To identify the various species of diphtheroids isolated as pure growth from clinical specimens whose Gram's smear revealed numerous inflammatory cells with Gram positive bacilli and had clinical evidence. A total of 100 isolates of Gram-positive bacilli from 16,242 clinical samples received in the Microbiology Department of Kasturba Medical College were considered for this study from Dec 2013-Dec 2014. Gram-positive bacilli which were seen in the smear along with pus cells, isolated as pure growth and reported as "Corynebacterium spp having clinical significance" were taken for this study while those which were reported as 'Probable skin contaminants' were excluded from this study. Species identification of Gram-positive bacilli was done by biochemical reactions. Antibiotic susceptibility test was done by Kirby-Bauer disk diffusion method. Biofilm production was done by the microtitre plate method of O'Toole and Kolter and statistical analysis was done by using proportion test and Chi-square test. Various species of diphtheroids were isolated from different clinical specimens. C. pseudotuberculosis, C. renale, C. ulcerans, C. striatum, C. minutissimum, Corynebacterium haemolyticum isolated from catheter tips, sputum, tracheostomy secretions and wound infections were highly resistant to many antibiotics while isolates from blood namely C. pseudotuberculosis, C. minutissimum, C. ulcerans and C. renale were nearly sensitive to most of them. It was also interesting to note that there was an increased rate of biofilm production in these isolates. Corynebacterium pseudotuberculosis, Coryne- bacterium ulcerans, Corynebacterium renale, Corynebacterium bovis, Corynebacterium striatum, Corynebacterium minutissimum, Corynebacterium pseudodiphtheriticum and Corynebacterium haemolyticum may survive in the form of biofilms in hospitals and cause multidrug resistant infections. Hence, we need to judiciously identify these organisms, find their antimicrobial susceptibility, treat them and thus prevent infections in hospitals.