Effect of Photoactivated Hypericin on Growth and Antibiotic Susceptibility of Hospital-Related Staphylococcus aureus and Enterococcus sp. Clinical Strains

Resistance against commonly used antibiotics is a serious clinical problem in recent medical practice. There exist several bacterial strains in which the possibilities of their inhibition are very limited due to multidrug resistance. Antimicrobial photodynamic therapy (aPDT) represents an option how to effectively suppress the growth of resistant pathogens. In this work we have studied interactions of potent photosensitizer hypericin (Hyp) with hospital-related gram positive (Gram+) and gram negative (Gram-) bacterial strains and the effects of photodynamic activated Hyp on bacterial susceptibility and/or resistance of these strains to antibiotics. We demonstrated a significant influence of photoactivated Hyp on growth of Staphylococcus aureus and Enterococcus sp. We have also shown that it is extremely important to use the effective concentrations of Hyp for aPDT, which completely inhibit the growth of microorganisms. Otherwise, there appears an increase in resistance, probably due to the activation of efflux mechanisms, which are involved in the efflux of Hyp and antibiotics as well.

A Binomial Model Approach: Comparing the R0 Values of SARS-CoV-2 rRT-PCR Data from Laboratories across Northern Cyprus

Northern Cyprus has implemented relatively strict measures in the battle against the outbreak of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The measures were introduced at the beginning of the COVID-19pandemic, in order to prevent the spread of the disease. One of these measures was the use of two separate realtime reverse transcription polymerase chain reaction (rRT-PCR) tests for SARS-CoV-2 referred to as the doublescreening procedure, which was adopted following the re-opening of the sea, air and land borders for passengersafter the first lockdown. The rRT-PCR double screening procedure involved reporting a negative rRT-PCR testwhich was carried in 72 to 120 h before departure whilst presenting no known symptoms of the COVID-19and performing a second rRT-PCR test at the point of arrival. This study compares the results of SARS-CoV-2rRT-PCR tests performed on incoming flight passengers from the 1st July to 9th of September 2020 to NorthernCyprus. The rRT-PCR test results collected by the Near East University (NEU) DESAM COVID-19 laboratory werecompared with the rRT-PCR test results collected by the Ministry of Health and/or private COVID-19 laboratoriesin Northern Cyprus. This comparative study was conducted using binomial distribution. In addition, by applyingthe Susceptible-Exposed-Infected-Removed (SEIR) model to Northern Cyprus, overall basic reproduction number(R0) value of the COVID-19 was analysed for the same time period to act as a threshold for this comparison.In both the statistical and SEIR mathematical model, R0 was calculated. It was assumed that, the more similarthe R0 results of NEU DESAM COVID-19 laboratory and other laboratories were with the overall R0 value ofNorthern Cyprus, the more reliable the results would be. We calculated that the median R0 values of the NEUDESAM COVID-19 laboratory and other laboratories performing the SARS-CoV-2 rRT-PCR on air passengersduring the studied period to be 0.96 and 1.29, respectively, compared to Northern Cyprus median R0 value whichwas 0.99. The rRT-PCR screening results from the NEU DESAM COVID-19 laboratory were closely aligned withthe screening results of Northern Cyprus whereas the screening results reported by other laboratories were not in afit with the regional pattern. This study also aimed to point out the importance of the rRT-PCR screening procedure since asymptomatic positive SARS-CoV-2 cases entery to Northern Cyprus was inhibited and this prevented thespread of the disease within the population.

Near Future Perspective of ESBL-Producing Klebsiella pneumoniae Strains Using Mathematical Modeling

While antibiotic resistance is becoming increasingly serious today,there is almost no doubt that more challenging times await us in the future.Resistant microorganisms have increased in the past decades leading to limited treatment options,along with higher morbidity and mortality.Klebsiella pneumoniae is one of the significant microorganisms causing major public health problems by acquiring resistance to antibiotics and acting as an opportunistic pathogen of healthcare-associated infections.The production of extended spectrumbeta-lactamases(ESBL)is one of the resistance mechanisms of K.pneumoniae against antibiotics.In this study,the future clinical situation of ESBL-producing K.pneumoniae was investigated in order to reflect the future scenarios to understand the severity of the issue and to determine critical points to prevent the spread of the ESBL-producing strain.For evaluation purposes,SIS-type mathematical modeling was used with retrospective medical data from the period from 2016 to 2019.Stability of the disease-free equilibrium and basic reproduction ratios were calculated.Numerical simulation of the SISmodel was conducted to describe the dynamics of non-ESBL and ESBL-producing K.pneumoniae.In order to determine the most impactful parameter on the basic reproduction ratio,sensitivity analysis was performed.A study on mathematical modeling using data on ESBL-producing K.pneumoniae strains has not previously been performed in any health institution in Northern Cyprus,and the efficiency of the parameters determining the spread of the relevant strains has not been investigated.Through this study,the spread of ESBL-producing K.pneumoniae in a hospital environment was evaluated using a different approach.According to the study,in approximately seventy months,ESBL-producing K.pneumoniae strains will exceed non-ESBL K.pneumoniae strains.As a result,the analyses showed that hospital admissions and people infected with non-ESBL or ESBL-producing K.pneumoniae have the highest rate of spreading the infections.In addition,it was observed that the use of antibiotics plays a major role in the spread of ESBL-producing K.pneumoniae compared to other risk factors such as in-hospital transmissions.As amatter of course,recoveries fromKlebsiella infections were seen to be the most effective way of limiting the spread.It can be concluded from the results that although the use of antibiotics is one of themost effective factors in the development of the increasing ESBL-producing K.pneumoniae,regulation of antibiotic use policy could be a remedial step together with effective infection control measures.Such steps may hopefully lead to decreased morbidity and mortality rates as well as improved medical costs.