Biology subjects

Jelocnik, M.

Publications and source records attributed to Jelocnik, M..

3 recordsLinked to original sources

bioRxiv2025

Prevalence of Pseudomonas aeruginosa in Australian wild birds, native wildlife, livestock and domestic animals

The ESKAPE pathogen, Pseudomonas aeruginosa, poses a serious threat to medical, veterinary, and agricultural practices globally. Understanding P. aeruginosa prevalence in wild bird populations, livestock, and domestic animals is vital for evaluating potential infection reservoirs. In this study, we screened 1,669 DNA samples obtained between 2010 and 2023 from healthy and diseased wild birds (n= 1,101), domestic animals (n= 269), livestock (n= 133), kangaroos (n= 39,) and koalas (n= 127) from Southeast Queensland, Australia, for both P. aeruginosa and overall bacterial load using an ecfX-16S rRNA duplex real-time PCR assay. P. aeruginosa-positive samples were also screened for the two most common fluoroquinolone resistance genotypes, GyrA Thr83Ile and GyrA Asp87Asn. Overall, only 1.8% samples were P. aeruginosa positive, a lower rate than reported in international studies. Livestock samples showed the highest P. aeruginosa prevalence (4.5%, n= 6), primarily horses (7.4%, n= 5), with wild birds (1.5%, n= 17), koalas (1.6% n= 2), and domestic animals (1.9%, n= 5) having the next highest rates. In contrast, no P. aeruginosa positive samples were identified in cattle (n= 45) or kangaroos (n= 39). Nearly all positive wild bird samples originated from eye swabs (94%, n=16). No additional correlation between swab site, health status, or admission cause was identified. The GyrA Thr83Ile variant was seen in 2/30 (6.6%) P. aeruginosa-positive samples, both of horse origin. Our findings provide important insight into the epidemiology of P. aeruginosa in Australian wildlife and domestic animal populations. Further prevalence studies, particularly covering a broader geographical region, are warranted to better elucidate nationwide P. aeruginosa carriage, infection, and fluoroquinolone resistance rates.

microbiology↗

bioRxiv2024

Development of shuttle vector-based transformation systems for Chlamydia pecorum and Chlamydia caviae

Chlamydia (C.) abortus, C. caviae and C. pecorum are obligate intracellular, zoonotic pathogens, which have all been associated with community-acquired pneumonia in humans. C. abortus is the causative agent of enzootic ovine abortion in small ruminants and can lead to miscarriage in women. C. caviae causes conjunctivitis in guinea pigs, while C. pecorum is found in livestock, resulting in economic losses and contributing to the decline of the koala population in Australia. Studying the biology of these bacteria has been challenging due to a dearth of genetic tools. This study aimed to establish transformation systems for C. abortus and C. pecorum using shuttle vectors and to expand upon already existing protocols for C. caviae. Shuttle vectors comprised the cryptic plasmid of the chlamydial species of interest, the pUC19 origin of replication (ori), a beta-lactamase (bla), and genes that mediate heterologous expression of fluorescent proteins (GFP, mNeonGreen, mScarlet). A C. suis-tailored transformation protocol and a previously established protocol for C. psittaci, C. trachomatis and C. pneumoniae were applied. While C. pecorum and C. caviae transformation experiments were successful, transformation of C. abortus remained ineffective. Shuttle vectors yielded stable transformants over several passages in the presence and absence of selective antibiotics while the fluorescence intensity of GFP was superior compared to mNeonGreen. Finally, we co-cultured GFP- and mScarlet-expressing C. pecorum strains demonstrating that both fluorophores can be detected in the same cell or even inclusion, possibly promoting homologous recombination. These findings open new avenues into our understanding of interstrain and interspecies co-infection dynamics both in vitro and in vivo.

microbiology↗

bioRxiv2020

Chlamydia gallinacea: genetically armed as a pathogen however a phenotypical commensal?

Chlamydia gallinacea is an obligate intracellular bacterium that has recently been added to the family of Chlamydiaceae. C. gallinacea is genetically diverse, widespread in poultry and a suspected cause of pneumonia in slaughterhouse workers. In poultry, C. gallinacea infections appear asymptomatic, but studies about the pathogenic potential are limited. In this study two novel sequence types of C. gallinacea were isolated from apparently healthy chickens. Both isolates (NL_G47 and NL_F725) were closely related to each other and showed 99.1% DNA sequence identity to C. gallinacea Type strain 08-1274/3. To gain further insight in the pathogenic potential, infection experiments in embryonated chicken eggs and comparative genomics with Chlamydia psittaci were performed. C. psittaci is an ubiquitous zoonotic pathogen of birds and mammals, and infection in poultry can result in severe systemic illness. In experiments with embryonated chicken eggs C. gallinacea induced mortality was observed, potentially strain dependent but lower compared to C. psittaci induced mortality. Comparative analyses confirmed all currently available C. gallinacea genomes possess the hallmark genes coding for known and potential virulence factors as found in C. psittaci albeit to a reduced number of orthologues or paralogs. The presence of (potential) virulence factors and the observed mortality in embryonated eggs indicates C. gallinacea should rather be considered as a (conditional) pathogen than an innocuous commensal. ImportanceChlamydiaceae are a family of bacteria comprising human and animal pathogens including the recently recognized Chlamydia gallinacea. C. gallinacea is widespread in poultry without causing clinical signs, which raises questions about its pathogenic potential. To assess this potential, two novel C. gallinacea strains were isolated, tested in infection experiments in embryonated chicken eggs and compared to C. psittaci. C. psittaci infection in poultry can result in severe systemic illness, depending on the conditions, and infections can be transmitted to humans. In the experiments C. gallinacea infection induced mortality of the embryo, but to a lower extent than infection with C. psittaci. Subsequent genome comparisons confirmed both C. gallinacea strains possess potential virulence genes typical for chlamydia, but fewer than C. psittaci. These results indicate C. gallinacea does have a pathogenic potential which warrants further research to elucidate its role as a poultry pathogen.

microbiology↗