[Outbreaks Due to Parasites: Examples from the World and Türkiye]

Outbreaks due to parasites can occur in various parts of the world and in different periods. These outbreaks can be caused by water and food, as well as by human-to-human or vector-borne transmission. Cryptosporidium spp. and Giardia intestinalis were among the pathogens that affected most people in water-borne outbreaks occurred in the world between 2010-2014. The chlorine resistance of both Cryptosporidium spp. and Giardia spp. leads to the widespread detection of these parasites in waterborne outbreaks. These two protozoans cause self-limiting watery diarrhea in immunocompetent individuals, but they can also cause chronic disease in certain situations. Apart from this, parasites such as Cyclospora spp., Cryptosporidium spp., Giardia intestinalis, Trichinella spp. and Toxoplasma gondii can also cause foodborne outbreaks. In Türkiye, outbreaks related to these parasites have emerged with the neglect of the notification. Some parasites transmitted from person to person can also pose a threat to public health in certain periods. Head lice, the most common examples of such parasites, can cause outbreaks in certain periods. Another example for human-induced parasitic outbreaks is scabies. There has been an increase in scabies rates in the world and in Türkiye, especially due to the Coronavirus disease-2019 (COVID-19) pandemic. In the first period of the pandemic, it was thought that due to the curfew restrictions, family members spending time at home might have led to an increase in the rate of scabies. On the other hand, as a result of the disruption of services due to COVID-19, the cases of malaria, a vector-borne disease, and the resulting deaths increased in 2020 compared to 2019 in the world. Although only imported malaria cases are detected in Türkiye today, there is a potential for an outbreak to occur at any time due to the presence of malaria vectors. An outbreak of imported malaria occurred in Mardin in 2012 due to a lorry driver entering the country from an endemic region. Immigrants that reside in Türkiye pose a risk for some infectious diseases due to the circumstances during migration or the conditions in their living areas. Leishmaniasis, which maintains its importance in the Mediterranean region, is another vector-borne disease and can be detected in Türkiye, especially in regions where immigrants reside. Bed bug infestations, which have increased recently, also closely affect the provision of health services. It is important to implement regular inspections in regions with outbreak potential, and to ensure the continuity of hygiene conditions and health services to prevent a possible outbreak. In case of an outbreak, different centers should cooperate, health authorities and academics should act together, patients and their contacts should be identified quickly and necessary precautions should be taken, the society should be informed and the outbreak should be taken under control in a short time. In this review article, outbreaks caused by parasites were examined under four headings as water, food, human and vector/arthropod-borne and examples from the world and Türkiye were given for these outbreaks.

Antibacterial activity of ciprofloxacin-impregnated 3D-printed polylactic acid discs: an in vitro study

Introduction: Three-dimensional (3D) printing technology allows incorporation of various substances including antibiotics into different structures. This study aimed to evaluate the antibacterial activity of ciprofloxacin-impregnated 3D discs against Escherichia coli. Methodology: Polylactic acid pellets were coated with ciprofloxacin at 1% and 2% concentrations, then filaments were produced from these pellets, and antibiotic-containing discs were obtained using fused deposition modeling 3D printers. The working temperatures during filament extrusion and 3D printing processes were 200 °C and 215 °C, respectively. Therefore, in order to test the thermal stability of ciprofloxacin during these processes, the antibiotic was exposed to 200 °C and 215 °C in an oven, and then tested against E. coli. Following this, efficiencies of antibiotic-coated pellets, filaments and discs against E. coli were determined by diffusion tests. Results: Ciprofloxacin heated at 200 °C and 215 °C was stable and retained its antibacterial activity. Pellets, filaments and discs coated with 1% or 2% concentration of ciprofloxacin produced inhibition zones in the culture plates. Increasing ciprofloxacin concentration did not significantly affect the diameter of inhibition zones (p > 0.05). Ciprofloxacin-containing polylactic acid pellets produced significantly larger inhibition zones than those of filaments and discs (p < 0.0001). The difference in zone diameters around ciprofloxacin-containing filaments and discs was not statistically significant (p > 0.05). Conclusions: Ciprofloxacin-coated polylactic acid-based 3D discs displayed antibacterial activity against E. coli. This suggests that, various polylactic acid-based ciprofloxacin-containing 3D products can be obtained and evaluated for antibacterial activity in future studies.

Serological screening of West Nile virus among blood donors in northern Cyprus

BACKGROUND

West Nile virus (WNV) is a neurotropic arbovirus that can also be transmitted through blood transfusion. Even though its geographic distribution has been expanding, there has not yet been any epidemiological data on WNV in northern Cyprus. The aim of our study is to fill this gap by using donated blood samples.

METHODS

Samples collected from the main government hospital blood bank in Nicosia were analyzed by anti-WNV enzyme-linked immunosorbent assay (ELISA) (immunoglobulin M [IgM] and immunoglobulin G [IgG]). Seropositive samples were subjected to plaque reduction neutralization test (PRNT) for confirmation and analyzed by ELISA IgG avidity test and reverse transcription real-time polymerase chain reaction (rRT-PCR).

RESULTS

Of the 760 sera samples, 2 (0.3%) were IgM+ and 31 (4.1%) were IgG+. Neutralization activity was detected in none (0.0%) of the IgM+ and 26 (83.9%) of IgG+ donor specimens. ELISA IgG avidity test reported high avidity in 21 (67.7%) and low avidity in one (3.2%) IgG+ sample. PRNT-confirmed anti-WNV IgG+ samples exhibited only borderline (19.2%) or high avidity (80.8%) values. rRT-PCR results were negative for both IgM+ and IgG+ samples.

CONCLUSION

Anti-WNV antibodies were detected in northern Cyprus among blood donors. The establishment of preventive measures and evaluation of the geographic extent of the WNV in northern Cyprus are highly recommended.

Extended-spectrum β-lactamase, plasmid-mediated AmpC β-lactamase, fluoroquinolone resistance, and decreased susceptibility to carbapenems in Enterobacteriaceae: fecal carriage rates and associated risk factors in the community of Northern Cyprus

Background

Antibiotic-resistant Enterobacteriaceae in the gastrointestinal flora can lead to infections with limited therapeutic options. Also, the resistant bacteria can be transferred from colonized persons to others. The present study was conducted to search the fecal carriage rates of (i) Enterobacteriaceae that produce extended-spectrum β-lactamase (ESBL-E) and/or (ii) plasmid-mediated AmpC β-lactamase (pAmpC-E), (iii) ciprofloxacin-resistant Enterobacteriaceae (CIP-RE), and (iv) carbapenem-intermediate or -resistant Enterobacteriaceae (CIRE) in Northern Cyprus.

Methods

A total of 500 community-dwellers were recruited from consecutive admissions to the clinical laboratories of four hospitals. One rectal swab or stool sample was collected from each participant. A questionnaire was applied to evaluate possible risk factors associated with intestinal colonization of resistant bacteria. The samples were cultured on antibiotic containing media to screen for resistant bacteria colonization. The bacterial colonies that grew on the plates were subjected to further phenotypic tests to confirm the resistance.

Results

Of 500 volunteers, ESBL-E, pAmpC-E, CIP-RE and CIRE carriage were detected in 107 (21.4%), 15 (3.0%), 51 (10.2%) and six (1.2%) participants, respectively. Escherichia coli was the most commonly recovered species among Enterobacteriaceae isolates. A significant proportion of ESBL-producing E. coli isolates (n = 22/107; 20.6%) was found to be co-resistant to CIP (p = 0.000, OR 3.21, 95% CI 1.76-5.87). In this study, higher socioeconomic status (CIP-RE: p = 0.024, OR 1.96, 95% CI 1.09-3.53), presence of gastrointestinal symptoms (CIRE: p = 0.033; OR 6.79, 95% CI 1.34-34.39), antibiotic use (ESBL-E: p = 0.031; OR 1.67, 95% CI 1.04-2.67; and CIRE: p = 0.033; OR 6.40, 95% CI 1.16-35.39), and travelling abroad (pAmpC-E: p = 0.010; OR 4.12, 95% CI 1.45-11.66) were indentified as risk factors.

Conclusion

The study indicates that resistant Enterobacteriaceae isolates are carried by humans in the community. To prevent further spread of resistance, rational use of antibiotics should be encouraged, and antibiotic resistance should be carefully monitored in Northern Cyprus.

An alternative DNA extraction method for detection of Blastocystis spp. in human fecal samples

Polymerase chain reaction (PCR) is an effective technique for diagnosis of Blastocystis infection. Notably, DNA isolation procedure is extremely critical for the PCR step. In the present study, a recently described extraction procedure, named as the "sand method" was modified and adapted for isolation of Blastocystis DNA. To evaluate its efficacy, the current method and QIAamp DNA Stool Mini Kit (Qiagen) were applied to fresh human stool samples. Our results indicated that, the mean DNA concentrations obtained by the sand method and the commercial kit were 48 and 55 ng/μl, respectively. Also, no DNA inhibitors were detected in two methods. The sand method was capable of detecting 16 parasites per 50 mg feces. DNA samples extracted by both methods were subjected to PCR. Blastocystis spp. were detected in 11 (31.4%) of 35 samples, and perfect agreement (κ: 1.000) was found between the PCR-sand method and PCR-commercial kit method. The samples that were detected positive by PCR-sand method were successfully sequenced, and Blastocystis subtypes (STs) were identified as ST3, ST2 and ST1. In conclusion, the present study indicates that the sand method provides a simple, rapid and inexpensive procedure for reliable extraction of Blastocystis DNA from stool samples.

Molecular identification of sulfadoxine-pyrimethamine resistance in malaria infected women who received intermittent preventive treatment in the Democratic Republic of Congo

Background

Point mutations in Plasmodium falciparum dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) genes which confer resistance to sulfadoxine-pyrimethamine (SP) occur at increasing rates. The present study aimed to identify Pfdhfr and Pfdhps mutations in P. falciparum isolates recovered from women who received two doses of SP during pregnancy in Bandundu, the Democratic Republic of Congo (DRC).

Methods

A total of 48 women with confirmed P. falciparum infection were enrolled in the study. Finger-prick blood samples that were collected on filter paper at the time of delivery were used for DNA isolation. Pfdhfr and Pfdhps genes were amplified by a nested PCR protocol. DNA sequencing was performed on both strands, and the point mutations were analysed.

Results

All of the 48 (100.0%) P. falciparum isolates carried at least one polymorphism in both genes. The wild-type haplotypes of Pfdhfr (CNCSI [C50, N51, C59, S108, I164]) and Pfdhps (SAKAA [S436, A437, K540, A581, A613]) were not observed in the study. In Pfdhfr, N51I (85.4%), C59R (60.4%), and S108N (100.0%) polymorphisms were detected. Triple mutation (CIRNI) (mutant amino acids are underlined) was the most prevalent (47.9%) Pfdhfr haplotype. In the study, all P. falciparum isolates (100.0%) harboured the A437G allele in Pfdhps gene. Also, K540E and A581G polymorphisms were observed in one (2.1%) isolate. Single mutant haplotype (SGKAA) was detected in 97.9% of the isolates. Mutant Pfdhfr and Pfdhps allele combinations revealed quintuple (CICNI-SGEGA; 2.1%), quadruple (CIRNI-SGKAA; 47.9%), triple (CICNI-SGKAA; 35.4%, CNRNI-SGKAA; 12.5%), and double (CNCNI-SGKAA; 2.1%) haplotypes.

Conclusions

In the study, the rate of SGEGA haplotype was low (2.1%). Although K540E and A581G alleles are more common in Eastern Africa, a distinct lineage of SGEGA is also present in the DRC, which is located in Central Africa. This haplotype is associated with decreased efficacy of SP in pregnant women and infants, therefore, it should be carefully considered in the DRC and SP resistance should be routinely monitored.

Epidemiology and Prevalence of Blastocystis spp. in North Cyprus

AbstractThis study was conducted to investigate the prevalence of Blastocystis spp. and its subtypes (STs) in North Cyprus; and to evaluate the presence of this parasite and its STs with respect to demographic, socioeconomic, and epidemiological factors, as well as gastrointestinal symptoms. Stool samples were collected from 230 volunteers. Each participant also filled out a questionnaire. The samples were examined microscopically by native-Lugol and trichrome methods and further tested by polymerase chain reaction (PCR) and sequencing. Prevalence of Blastocystis spp. infection was found to be 10.5%, 10.5%, and 27.8%, by direct microscopy, trichrome method, and PCR, respectively. No other parasites were detected in the specimens except Giardia spp. (n = 2; 0.8%) and Entamoeba coli (n = 1; 0.4%). The most common Blastocystis STs were ST3 (20; 31.2%), ST2 (18; 28.2%), ST1 (8; 12.5%), and ST4 (7; 11%); whereas other STs were identified as ST6 (3; 4.7%), ST7 (2; 3.2%), and non-ST (6; 9.4%). Presence of Blastocystis spp. and its STs was not significantly related to any of the demographic, socioeconomic, and epidemiological factors. Furthermore, no significant association of Blastocystis spp. and its STs with gastrointestinal symptoms was found. This study is the first investigation of the epidemiology of Blastocystis spp. in North Cyprus. Distribution of Blastocystis spp. and its STs among demographic, socioeconomic, and epidemiological factors showed complete homogeneity. Presence of the parasite and its STs was not significantly related with the gastrointestinal symptoms among symptomatic and asymptomatic individuals. These findings suggest that Blastocystis spp. may be part of the intestinal flora in humans.

Is "dried stool spots on filter paper method (DSSFP)" more sensitive and effective for detecting Blastocystis spp. and their subtypes by PCR and sequencing?

PCR and DNA sequencing are currently the diagnostic methods of choice for detection of Blastocystis spp. and their suptypes. Fresh or frozen stool samples have disadvantages in terms of several aspects such as transportation, storage, and existence of PCR inhibitors. Filter paper technology may provide a solution to these issues. The aim of the present study was to detect Blastocystis spp. and their subtypes by employing two different preservation methods: conventional frozen stool (FS) and dried stool spots on filter paper (DSSFP). Concentration and purity of DNA, sensitivity of PCR, and DNA sequencing results obtained from the two methods were also compared. A total of 230 fecal samples were included and separated into two parts: one part of the fecal samples were directly frozen and stored at -20 °C. The remaining portion of the specimens were homogenized with saline and spread onto the filter papers as thin layer with a diameter of approximately 3 cm. After air-dried, the filter papers were stored at room temperature. DSSFP samples were collected by scraping from the filter papers. DNA were extracted by EURx Stool DNA Extraction Kit from both samples. Concentration and purity were measured with Nano-Drop, then PCR and sequencing were conducted for detection of Blastocystis spp. and its genotypes. Pure DNA was obtained with a A260/A280 ratio of 1.7-2.2 in both methods. DNA yield from FS was 25-405 ng/μl and average DNA concentration was 151 ng/μl, while these were 7-339 and 122 ng/μl for DSSFP, respectively. No PCR inhibition was observed in two methods. DNA from DSSFP were found to be stable and PCR were reproducible for at least 1 year. FS-PCR- and DSSFP-PCR-positive samples were 49 (21.3 %) and 58 (25.3 %), respectively (p = 0.078). The 43 specimens were concordantly positive by both FS-PCR and DSSFP-PCR. When the microscopy was taken as the gold standard, sensitivity of DSSFP-PCR and FS-PCR was 95.5 and 86.4 %, while specificity of both tests was 99.4 and 98.3 %, respectively. DNA sequencing results of 19 microscopically confirmed cases were strictly identical (concordance 100 %) in both methods, and ST2:6, ST3:8, ST4:3, and ST6:2 were the detected subtypes. Among the 230 fecal samples, the most predominant subtypes were ST3, ST2, ST4, and ST1 by both FS and DSSFP methods. Concordance of DNA sequencing results obtained from the two methods was noted to be 90.7 %. To our knowledge, this is the first study that demonstrates DNA extraction from DSSFP is more sensitive and effective than the FS method for diagnosis of Blastocystis spp. and their subtypes by PCR and DNA sequencing.

Effect of mixing techniques on bacterial attachment and disinfection time of polyether impression material

Objective:

The aim of this study was 2-fold. The first aim was to evaluate the effects of mixing technique (hand-mixing or auto-mixing) on bacterial attachment to polyether impression materials. The second aim was to determine whether bacterial attachment to these materials was affected by length of exposure to disinfection solutions.

Materials and Methods:

Polyether impression material samples (n = 144) were prepared by hand-mixing or auto-mixing. Escherichia coli, Staphylococcus aureus and Pseudomonas aeruginosa were used in testing. After incubation, the bacterial colonies were counted and then disinfectant solution was applied. The effect of disinfection solution was evaluated just after the polymerization of impression material and 30 min after polymerization. Differences in adherence of bacteria to the samples prepared by hand-mixing and to those prepared by auto-mixing were assessed by Kruskal-Wallis and Mann-Whitney U-tests. For evaluating the efficiency of the disinfectant, Kruskal-Wallis multiple comparisons test was used.

Results:

E. coli counts were higher in hand-mixed materials (P < 0.05); no other statistically significant differences were found between hand- and auto-mixed materials. According to the Kruskal-Wallis test, significant differences were found between the disinfection procedures (Z > 2.394).

Conclusion:

The methods used for mixing polyether impression material did not affect bacterial attachment to impression surfaces. In contrast, the disinfection procedure greatly affects decontamination of the impression surface.

[Evaluation of Tetrazolium Violet and Resazurin Assays for Ciprofloxacin Susceptibility Testing of Resistant Mycobacterium tuberculosis Isolates]

Tuberculosis, caused by Mycobacterium tuberculosis, is still a serious public health concern. Antimycobacterial drug resistance which is in an increasing trend worldwide aids to the importance of tuberculosis problem. Fluoroquinolones which exhibit in vitro and in vivo anti-mycobacterial activity, are being recommended by World Health Organization as alternative drugs particularly for the treatment of multidrug resistant tuberculosis. Rapid detection of antimycobacterial resistance is of great importance for the effective treatment of patients with tuberculosis. In this study, we evaluated the efficiency of tetrazolium violet (TV) and resazurin (RES) assays in terms of rapid detection of bacterial growth and ciprofloxacin resistance in M.tuberculosis clinical isolates. Thirty M.tuberculosis isolates which were resistant to at least one of the first-line anti-tuberculosis drugs were tested using TV and RES assays in addition to gold standard agar proportion test. Standard strain M.tuberculosis H37Ra was also included in each run. The tests were performed in four sets as TV and RES were added on day 5, 7, 10 and 12. For the TV assay, any change in colour from yellow to dark purple was recorded as bacterial growth. For the RES assay, any change in colour from blue to pink was recorded as bacterial growth. The optimal incubation period for detection of growth and resistance was 7 days for 25 of 30 bacteria. However, results for five isolates with low inoculum rates were detected on 10th and 12th days. Any change in colour in drug containing media was recorded as resistance to ciprofloxacin. All the susceptibility results were consistent with those obtained from agar proportion method. As indicated by our results, TV and RES assays are rapid and simple tests which could be used for detection of bacterial growth and ciprofloxacin resistance in M.tuberculosis clinical isolates. Widespread use of such colorimetric tests will help to minimize the need of sophisticated expensive susceptibilty test systems particularly in low income countries.

Conformational flexibility determines selectivity and antibacterial, antiplasmodial, and anticancer potency of cationic α-helical peptides

We used a combination of fluorescence, circular dichroism (CD), and NMR spectroscopies in conjunction with size exclusion chromatography to help rationalize the relative antibacterial, antiplasmodial, and cytotoxic activities of a series of proline-free and proline-containing model antimicrobial peptides (AMPs) in terms of their structural properties. When compared with proline-free analogs, proline-containing peptides had greater activity against Gram-negative bacteria, two mammalian cancer cell lines, and intraerythrocytic Plasmodium falciparum, which they were capable of killing without causing hemolysis. In contrast, incorporation of proline did not have a consistent effect on peptide activity against Mycobacterium tuberculosis. In membrane-mimicking environments, structures with high α-helix content were adopted by both proline-free and proline-containing peptides. In solution, AMPs generally adopted disordered structures unless their sequences comprised more hydrophobic amino acids or until coordinating phosphate ions were added. Proline-containing peptides resisted ordering induced by either method. The roles of the angle subtended by positively charged amino acids and the positioning of the proline residues were also investigated. Careful positioning of proline residues in AMP sequences is required to enable the peptide to resist ordering and maintain optimal antibacterial activity, whereas varying the angle subtended by positively charged amino acids can attenuate hemolytic potential albeit with a modest reduction in potency. Maintaining conformational flexibility improves AMP potency and selectivity toward bacterial, plasmodial, and cancerous cells while enabling the targeting of intracellular pathogens.

[Recent developments in SARS vaccine studies]

Severe acute respiratory syndrome (SARS) caused thousands of human infections worldwide and hundreds of deaths in just a few months. Evidence indicates that SARS coronavirus (SARS-CoV) has been circulating from animals to humans since before the 2002-2003 outbreak, suggesting that another pandemic may occur. This possibility has focused continuous action on SARS vaccine research. Inactivated vaccines, viral and bacterial vector vaccines, recombinant protein vaccines, subunit vaccines, DNA vaccines, and live-attenuated virus vaccines have been studied in different animal models. Although different animal models are used in vaccine studies, the most appropriate model for studying SARS is ferret since it develops the typical clinical signs, viral replication patterns and lung pathology compatible with that of SARS pathogenesis in humans. While there is much evidence that various vaccine strategies against SARS are safe and immunogenic, vaccinated animals still display significant disease upon challenge. Moreover, potential vaccine enhancement of SARS have also been shown in some studies. Data from the studies give an important information of the demand for further vaccine development research, especially focusing on mucosal immunization, T-cell immunity and combinations of heterologous vaccines in prime-boost regimens. In this review article developments on SARS vaccines have been discussed under the light of recent literature.

Cotunneling-mediated transport through excited states in the Coulomb-blockade regime

We present finite-bias transport measurements on a few-electron quantum dot. In the Coulomb-blockade regime, strong signatures of inelastic cotunneling occur which can directly be assigned to excited states observed in the nonblockaded regime. In addition, we observe structures related to sequential tunneling through the dot, occurring after it has been excited by an inelastic cotunneling process. We explain our findings using transport calculations within the real-time Green's function approach, including diagrams up to fourth order in the tunneling matrix elements.

[CT stereotactic biopsy in the differential diagnosis of deeply situated intracerebral hematomas]

The diagnosis of intracerebral haematomas, especially of those which are relatively small, occupy little space and are deeply situated, presents considerable problems. The problem is even greater when the expected acute case history and the acute beginning of the symptoms do not occur and unusual localisations are found. The consequences of this are false diagnoses and the treatment of these patients within the framework of blanket diagnosis "intracerebral tumours" or "space occupying processes" without any confirmation of the histological diagnosis. - Using a sample of 26 patients where the histological diagnosis of non-recent intracerebral hemorrhages had been confirmed (out of a series of 818 CT-stereotactically biopsied patients punctured by us from the beginning of 1983 until the end of 1984), the problem of establishing a diagnosis is exposed. - A histological diagnoses should in any case be confirmed before any thorough and deep-reaching therapy is begun, since false diagnoses and misinterpretations can cause serious consequences for the patient.