Journal of Medical Microbiology

Candida tropicalishas been identified as the most prevalent pathogenic yeast species of theCandida-non-albicansgroup. Historically,Candida albicanshas been the major species responsible for causing candidiasis in immunocompromised and immunocompetent patients. However, infections (candidiasis) due toC. tropicalishave increased dramatically on a global scale thus proclaiming this organism to be an emerging pathogenic yeast. The reasons for this organism's dominance and its resistance to fluconazole have been difficult to elucidate. In addition, the mechanism of this organism's pathogenicity and the consequent immune response remain to be clarified. This paper describes certain predisposing factors potentially responsible for these characteristics and presents a ‘root cause analysis' to explain the increasing prevalence ofC. tropicalisin developed and undeveloped countries, as well as the organism's acquired drug resistance. Control measures against fluconazole resistance in clinical management have also been discussed.

Non-thermal (low-temperature) physical plasma is under intensive study as an alternative approach to control superficial wound and skin infections when the effectiveness of chemical agents is weak due to natural pathogen or biofilm resistance. The purpose of this study was to test the individual susceptibility of pathogenic bacteria to non-thermal argon plasma and to measure the effectiveness of plasma treatments against bacteria in biofilms and on wound surfaces. Overall, Gram-negative bacteria were more susceptible to plasma treatment than Gram-positive bacteria. For the Gram-negative bacteriaPseudomonas aeruginosa,Burkholderia cenocepaciaandEscherichia coli, there were no survivors among the initial 10⁵c.f.u. after a 5 min plasma treatment. The susceptibility of Gram-positive bacteria was species- and strain-specific.Streptococcus pyogeneswas the most resistant with 17 % survival of the initial 10⁵c.f.u. after a 5 min plasma treatment.Staphylococcus aureushad a strain-dependent resistance with 0 and 10 % survival from 10⁵c.f.u. of the Sa 78 and ATCC 6538 strains, respectively.Staphylococcus epidermidisandEnterococcus faeciumhad medium resistance. Non-ionized argon gas was not bactericidal. Biofilms partly protected bacteria, with the efficiency of protection dependent on biofilm thickness. Bacteria in deeper biofilm layers survived better after the plasma treatment. A rat model of a superficial slash wound infected withP. aeruginosaand the plasma-sensitiveStaphylococcus aureusstrain Sa 78 was used to assess the efficiency of argon plasma treatment. A 10 min treatment significantly reduced bacterial loads on the wound surface. A 5-day course of daily plasma treatments eliminatedP. aeruginosafrom the plasma-treated animals 2 days earlier than from the control ones. A statistically significant increase in the rate of wound closure was observed in plasma-treated animals after the third day of the course. Wound healing in plasma-treated animals slowed down after the course had been completed. Overall, the results show considerable potential for non-thermal argon plasma in eliminating pathogenic bacteria from biofilms and wound surfaces.

The acute dental abscess is frequently underestimated in terms of its morbidity and mortality. The risk of potential serious consequences arising from the spread of a dental abscess is still relevant today with many hospital admissions for dental sepsis. The acute dental abscess is usually polymicrobial comprising facultative anaerobes, such as viridans group streptococci and the Streptococcus anginosus group, with predominantly strict anaerobes, such as anaerobic cocci, Prevotella and Fusobacterium species. The use of non-culture techniques has expanded our insight into the microbial diversity of the causative agents, identifying such organisms as Treponema species and anaerobic Gram-positive rods such as Bulleidia extructa, Cryptobacterium curtum and Mogibacterium timidum. Despite some reports of increasing antimicrobial resistance in isolates from acute dental infection, the vast majority of localized dental abscesses respond to surgical treatment, with antimicrobials limited to spreading and severe infections. The microbiology and treatment of the acute localized abscess and severe spreading odontogenic infections are reviewed.

Klebsiella pneumoniaecauses infections in humans especially in immunocompromised patients. About 80 % of nosocomial infections caused byK. pneumoniaeare due to multidrug-resistant strains. The emergence of antibiotic-resistant bacterial strains necessitates the exploration of alternative antibacterial therapies, which led our group to study the ability of bacterial viruses (known as bacteriophages or simply phages) to treat mice challenged withK. pneumoniae. Phage SS specific forK. pneumoniaeB5055 was isolated and characterized, and its potential as a therapeutic agent was evaluated in an experimental model ofK. pneumoniae-mediated lobar pneumonia in mice. Mice were challenged by intranasal (i.n.) inoculation with bacteria (10⁸ c.f.u. ml⁻¹). A single intraperitoneal injection of 10¹⁰ p.f.u. ml⁻¹phage administered immediately after i.n. challenge was sufficient to rescue 100 % of animals fromK. pneumoniae-mediated respiratory infections. Administration of the phage preparation 3 h prior to i.n. bacterial challenge provided significant protection in infected mice, while even 6 h delay of phage administration after the induction of infection rendered the phage treatment ineffective. The results of this study therefore suggest that the timing of starting the phage therapy after initiation of infection significantly contributes towards the success of the treatment.