What Is Going on in Indoor Air Quality of a University Hospital in Northern Cyprus?

Background: There are two main purposes of microbial monitoring of the inanimate hospital environment. One of them is to monitor hygiene standards, and the second is to determine the presence of nosocomial pathogens. This study was aimed to investigate the indoor environment of the different departments of a university hospital. Methods: The prospective study was conducted in a university hospital, a teaching hospital with 143 beds and 30 ICU beds, and a hospital with 6 different wards in Northern Cyprus. Active air sampling was done by using an air IDEAL 3P device. Air samples were taken at 38 points defined before in different parts of the hospital. Results: Our results showed a low level of microorganisms' numbers in microbial airborne communities in a university hospital. Moreover, our results indicated that the temperature of the hospital's indoor environment is not significantly related to the airborne microbial community. On the other hand, our results indicate that the Aspergillus species were mostly isolated in the drug preparation room. Conclusion: The studies have shown that one of the causes of hospital infections is the microorganisms entering the airborne microbial communities. In this case, epidemiology and pathogenesis of airborne microbial communities should be understood.

[Comparative Analyses of IgA Antibody Response of Non-COVID-19 Infected People Over 60 Years Old Following CoronaVac and Pfizer-BioNTech COVID-19 Vaccination]. / COVID-19 Enfeksiyonu Geçirmeyen 60 Yas Üstü Kisilerde CoronaVac ve Pfizer-BioNTech Asisi Sonrasi IgA Antikor Yaniti Karsilastirilmasi.

The formation rate, magnitude, and duration of the antibody-mediated humoral immune response that develops against different viral proteins of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) are considered important in vaccine success. It is known that the response to vaccinations decreases due to immunosenescence in older adults. This study was aimed to investigate the levels of serum IgA response at 1st and 3rd month after vaccination of people over 60 years old who were immunized with CoronaVac and Pfizer-BioNTech. A total of 35 people living in the North Cyprus who have not previously had COVID-19 infection were included in the study. After the 2nd dose of vaccination, serum IgA levels were measured after the 1st and 3rd month with the anti-SARS-CoV-2 IgA (Euroimmun, Lubeck, Germany) kit. The statistical significance was determined as 0.05 in the whole study. SPSS and GraphPad Prism software were used for calculations, analyses and graphs. The possible effect of demographic variables on serum IgA level was compared between the vaccine groups and it was found that there was no statistically significant difference between them. For the IgA titer-positive individuals who had been vaccinated with the Pfizer-BioNTech vaccine, for both 1st and 3rd months were observed to be higher than CoronaVac vaccinated IgA titer-positive individuals. In individuals who received the CoronaVac vaccine, there was a statistically significant change in serum IgA levels between 1st and 3rd months, but there was no statistically significant change in the Pfizer-BioNTech vaccine administered group. When the Pfizer/BioNTech and CoronaVac vaccines were compared with each other in terms of serum IgA antibody titers, it was found that the mean serum IgA levels of the individuals in the Pfizer/BioNTech group were statistically higher at the 1st and 3rd months than the CoronaVac group. Serum IgA titers in both vaccine groups were statistically significantly decreased from 1st month to 3rd month. This study showed that the Pfizer/BioNTech vaccine induced higher SARS-CoV-2 specific serum IgA antibodies than the CoronaVac vaccine and remained seropositive for a longer time in individuals aged 60 years and older. It is believed that the serum IgA levels that were determined may not reflect the serum IgA levels. However, these findings support the studies in other literature, showing that the Pfizer-BioNTech mRNA vaccine induces higher SARS-CoV-2 specific serum IgA antibodies than the inactive CoronaVac vaccine and that it remains seropositive for a longer period of time. This study is important as it is the first study to compare the SARS-CoV-2 IgA antibody responses of individuals over 60 years of age in the Turkish Republic of Northern Cyprus in two different vaccine groups.

Comparative humoral response of mRNA and inactivated vaccines against COVID-19 in healthy adults aged 60 years and older.

INTRODUCTION: A vaccine against coronavirus disease 2019 (COVID-19) is critically needed for older adults because of the increased morbidity and mortality rates. METHODOLOGY: In this prospective study, we analysed the titre magnitude of the IgG antibodies directed against the SARS-CoV-2 Spike Protein S1 (S1-RBD) antigen in both CoronaVac and Pfizer-BioNTech groups. The samples were tested to detect antibodies that bind to the receptor-binding domain of the spike protein of SARS-CoV-2 using the Enzyme-Linked Immunosorbent Assay (ELISA) technique with SARS-CoV-2 IgG II Quant. The cut-off value was > 50 AU/mL. GraphPad Prism software was used. Statistical significance was defined at p < 0.05. RESULTS: The CoronaVac group (12 females, 13 males) had a mean age of 69.64 ± 1.38 years. The Pfizer-BioNTech group (13 males, 12 females) had a mean age of 72.36 ± 1.44 years. The anti- S1-RBD titre decrease rate from the 1st to the 3rd month for CoronaVac and Pfizer-BioNTech groups was 74.31% and 86.48%, respectively. There was no statistically significant difference in the antibody titre between the 1st month and 3rd month for the CoronaVac group. However, there was a significant difference between the 1st and 3rd month in the Pfizer-BioNTech group. In addition, there was no statistically significant difference in the genders between the 1st and 3rd month of the antibody titres for both the CoronaVac Pfizer-BioNTech group. CONCLUSIONS: The levels of anti-S1-RBD, the preliminary outcome data of our study, represents one piece of the puzzle of humoral response and duration of vaccination protection.

Investigation of Brucella canis and Brucella abortus Seropositivity by In-House Rapid Slide Agglutination Test and In-House ELISA in Northern Cyprus.

The incidence of Brucella canis (B. canis) in humans is unknown in Northern Cyprus. In this study, we investigated the prevalence of B. canis and Brucella abortus (B. abortus) infection in human sera and evaluated the results obtained by agglutination-based techniques using standardized antigens made from B. canis comparatively. All of the subjects were negative in terms of Rose-Bengal plate test. Undiluted serum samples were initially screened by rapid slide agglutination test (RSAT), and those which were found positive were retested in the dilution of 1/25-1/200. Confirmation of the positive results was performed by using 2-mercaptoethanol standard agglutination test (SAT). The test antigen was prepared from the less mucoid M (-) variant of B. canis, and 1/1,048 titered dog antiserum was used as positive control. In 225 serum samples, 3.6% (8/225) was positive by B. canis M (-) RSAT, 4.4 % (10/225) was positive by B. canis M (-) indirect enzyme-linked immunosorbent assay (iELISA). 5.3% (12/225) was positive by B. abortus S99 RSAT and 9.8% (22/225) was positive by B. abortus S99 iELISA. Nine samples were positive by both B. abortus S99 RSAT and B. abortus S99 iELISA. Seven samples were positive by both B. canis M (-) RSAT and B. canis M (-) iELISA. One patient was positive by all methods. It is important to evaluate patient samples with RSAT and iELISA. Until the notification system gives better results to the Ministry of Health, in order to reach the real data for Northern Cyprus, multicenter prevalence determination studies should be done for future.

[Investigation of Leishmania infantum Seroprevalance and Leishmaniasis Knowledge Level in Northern Cyprus]. / Kuzey Kibris'ta Leishmania infantum Seroprevalansinin ve Leysmanyaz Bilgi Düzeyinin Arastirilmasi.

Leishmaniasis is an infectious disease caused by Leishmania parasites, transmitted by sand flies and common in the Mediterranean region. Cyprus is located in the east of Mediterranean Sea and is considered endemic for Leishmaniasis. In our study, it was aimed to investigate Leishmania infantum IgG seropositivity in healthy volunteers living in different regions of Northern Cyprus and to determine the risk factors for Leishmaniasis and measure the level of public knowledge about the disease. A total of 300 healthy volunteers (farmer/livestock: 100, hunter: 100, control group: 100) from five different regions of Northern Cyprus were included in the study, including Nicosia, Kyrenia, Famagusta, Morphou/Lefka, and Trikomo/Karpasia. The participants' blood was drawn and prepared questionnaire forms were filled out. Collected blood was centrifuged and the serum samples were separated and stored at -80ºC until the day of the test. All serum samples were tested for L.infantum IgG specific antibodies using the ELISA method (NovaTec, Immundiagnostica GmbH, Germany) in accordance with the manufacturer's recommendations. L.infantum IgG positivity was found to be 4.7% (14/300). The mean ages of L.infantum IgG positive and negative participants were 43.64 ± 11.74 and 42.17 ± 14.32 respectively. There was no statistically significant relationship between seropositivity and age (p= 0.706). The positivity rate was found to be significantly higher in hunters and farmers/livestocks compared with the control group (p= 0.020). In addition, it was determined that having a dog and the number of dogs owned were significantly associated with Leishmaniasis (p= 0.017, p= 0.020, respectively). On the other hand, 77% (231/300) of the volunteers included in our study had no prior knowledge about the disease. When compared to the other study groups, it was determined that hunters had the most knowledge of the Leishmaniasis infection (p= 0.001). Moreover, it was observed that as the education level of the participants increased, the level of knowledge about the disease also increased in parallel (p≤ 0.001). According to the results in our study, L.infantum IgG seropositivity was undeniably high in the healthy population living in Northern Cyprus. It is clear that outdoor activities such as hunting or dealing with farming/livestock are risk factors for the disease. In this context, it is apparent that more clear results will be obtained about the prevalence of the disease with the conduction of large-scale epidemiological studies. As a result, we concluded that especially risk groups should be informed about the current status of Leishmaniasis infection and necessary precautions should be taken.

In Vitro Analysis of Microbiologic Sealing of Two Different Fixed Implant-Supported Prosthesis Designs Cemented By Four Different Dental Cements.

PURPOSE: Despite the high success rate of implant-supported fixed restorations in dentistry, there is a lack of evidence on the marginal seal for dental cement. Thus, this study aimed to evaluate the marginal seal of implant-supported crowns and partial dentures cemented using four different dental cements. MATERIALS AND METHODS: The study evaluated the marginal seal of implant-supported crowns and partial dentures cemented using zinc phosphate, resin-modified glass-ionomer, self-adhesive resin, and noneugenol, acrylic-urethane polymer-based temporary dental cements. After cementation and thermal cycling procedures, the samples were incubated in Escherichia coli suspension for 5 days at 37°C under an aerobic environment. After debonding the restorations under sterile conditions, sterile cotton swabs were used to obtain microbial samples from the inner surface of each restoration and abutment surface. To analyze the contamination, each sample was immersed in a brain-heart infusion culture medium and incubated at 37°C for 24 hours, and then, the colony-forming units were counted and recorded. RESULTS: Regarding the number of colonies for Escherichia coli, the results revealed no substantial difference between the crowns and the fixed partial restorations (P = .25). However, the differences in the level of contamination between the cement groups were significant (P ≤ .001). The self-adhesive resin cement samples showed the lowest level of contamination, followed by the zinc phosphate and resin-modified glass-ionomer cements. The difference in the level of contamination between these groups was not significant. The temporary cement group exhibited significantly higher numbers of bacterial colonies in comparison to the other cement groups. CONCLUSION: Self-adhesive resin cement has better biologic properties for retaining implant-supported restorations than other types of dental cement.

Automated detection of Mycobacterium tuberculosis using transfer learning.

INTRODUCTION: Quantitative analysis of Mycobacterium tuberculosis using microscope is very critical for diagnosing tuberculosis diseases. Microbiologist encounter several challenges which can lead to misdiagnosis. However, there are 3 main challenges: (1) The size of Mycobacterium tuberculosis is very small and difficult to identify as a result of low contrast background, heterogenous shape, irregular appearance and faint boundaries (2) Mycobacterium tuberculosis overlapped with each other making it difficult to conduct accurate diagnosis (3) Large amount of slide can be time consuming and tedious to microbiologist and which can lead to misinterpretations. METHODOLOGY: To solve these challenges and limitations, we proposed an automated-based detection method using pretrained AlexNet to trained the model in 3 sets of experiments A, B and C and adjust the protocols accordingly. We compared the detection of tuberculosis using AlexNet Models with the ground truth result provided by microbiologist and analyzed inconsistencies between network models and human. RESULTS: 98.15 % accuracy, 96.77% sensitivity and 100% specificity for experiment A, 98.09% accuracy, 98.59% sensitivity and 97.67% specificity for experiment B and 98.73% testing accuracy, 98.59 sensitivity, 98.84% specificity ofr experiment C which sound robust and promising. CONCLUSIONS: The results indicated that network performance was successful with high accuracies, sensitivities and specificities and it can be used to support microbiologist for diagnosis of tuberculosis.

Hepatitis B Virus: From Diagnosis to Treatment.

Hepatitis B infection is still a global concern progressing as acute-chronic hepatitis, severe liver failure, and death. The infection is most widely transmitted from the infected mother to a child, with infected blood and body fluids. Pregnant women, adolescents, and all adults at high risk of chronic infection are recommended to be screened for hepatitis B infection. The initial analysis includes serological tests that allow differentiation of acute and chronic hepatitis. Molecular assays performed provide detection and quantification of viral DNA, genotyping, drug resistance, and precore/core mutation analysis to confirm infection and monitor disease progression in chronic hepatitis B patients. All patients with chronic hepatitis B should be treated with antiviral medications and regularly monitored for efficient treatment. The current treatment is based on nucleos(t)ide analogs and pegylated interferons that save lives by decreasing liver cancer death, liver transplant, slow or reverse the progression of liver disease as well as the virus infectivity.

Evaluation of the pol/S Gene Overlapping Mutations in Chronic Hepatitis B Patients in Northern Cyprus.

Mutations associated with the pol and the S gene can emerge as a consequence of the high replication capacity and proofreading deficiencies of hepatitis B virus during replication. The current study was constructed to evaluate primary, partial, compensatory and the escape mutations in chronic hepatitis B patients in Northern Cyprus. The samples of HBsAg positive treatment naïve 100 patients were involved in this study. HBV pol gene region was sequenced, amplified and HBV pol/S gene mutations were determined. The samples of thirty-two patients were excluded because of their low viral load (HBV < 1000 iu/ml). Among the sequenced 68 samples, there was a partial mutation (1.5%) and 36.7% displayed a resistance profile to lamivudine, adevofir, and telbivudine. Immune response escape, vaccine escape, HBIg and diagnosis escape mutations were determined in 24%, 10%, 6%, and 4% samples of the patients, respectively. Additionally, there were six different combined mutations. These data underscored that there is no concern for primary mutations in Northern Cyprus, however, we have identified a compensatory mutation (rtV173M) that may have primary mutation characteristics by combining with other mutation patterns. Additionally, HBsAg escape mutants demonstrated that detection of the S gene together with the pol gene mutations might be beneficial and important to monitor the surveillance of S variants.Mutations associated with the pol and the S gene can emerge as a consequence of the high replication capacity and proofreading deficiencies of hepatitis B virus during replication. The current study was constructed to evaluate primary, partial, compensatory and the escape mutations in chronic hepatitis B patients in Northern Cyprus. The samples of HBsAg positive treatment naïve 100 patients were involved in this study. HBV pol gene region was sequenced, amplified and HBV pol/S gene mutations were determined. The samples of thirty-two patients were excluded because of their low viral load (HBV < 1000 iu/ml). Among the sequenced 68 samples, there was a partial mutation (1.5%) and 36.7% displayed a resistance profile to lamivudine, adevofir, and telbivudine. Immune response escape, vaccine escape, HBIg and diagnosis escape mutations were determined in 24%, 10%, 6%, and 4% samples of the patients, respectively. Additionally, there were six different combined mutations. These data underscored that there is no concern for primary mutations in Northern Cyprus, however, we have identified a compensatory mutation (rtV173M) that may have primary mutation characteristics by combining with other mutation patterns. Additionally, HBsAg escape mutants demonstrated that detection of the S gene together with the pol gene mutations might be beneficial and important to monitor the surveillance of S variants.

A Special Risk Group for Hepatitis E Infection: The First Record of North Cyprus.

Hepatitis E virus (HEV) is transmitted by a fecal oral route from animals to humans following exposure to the body fluids of infected animals. We investigated the seroprevalence of anti-hepatitis E (anti-HEV) antibodies by monitoring IgG and IgM virus antibodies amongst employees in the animal industry in North Cyprus through a cross-sectional study. Samples were taken from individuals without occupational exposure to animals and from those who worked with animals (doing animal husbandry, veterinary work or butchery). Enzyme-linked immunoassays were used to detect anti-HEV IgG and IgM in the blood samples. The prevalence of anti-HEV IgG antibodies was 3.0% (12/400), while the prevalence of anti-HEV IgM antibodies was 0.25% (1/400). The prevalence of anti-HEV IgG amongst the samples received from females was approximately 2.5-fold higher than samples received from males (2.4%). Anti-HEV IgG was detected amongst 7% of animal husbandry workers and amongst 2% of veterinarians and butchers. The current findings represent the first records of HEV surveillance in Cyprus. We investigated the seroprevalence of anti-HEV by monitoring IgG and IgM virus antibodies amongst employees.Hepatitis E virus (HEV) is transmitted by a fecal oral route from animals to humans following exposure to the body fluids of infected animals. We investigated the seroprevalence of anti-hepatitis E (anti-HEV) antibodies by monitoring IgG and IgM virus antibodies amongst employees in the animal industry in North Cyprus through a cross-sectional study. Samples were taken from individuals without occupational exposure to animals and from those who worked with animals (doing animal husbandry, veterinary work or butchery). Enzyme-linked immunoassays were used to detect anti-HEV IgG and IgM in the blood samples. The prevalence of anti-HEV IgG antibodies was 3.0% (12/400), while the prevalence of anti-HEV IgM antibodies was 0.25% (1/400). The prevalence of anti-HEV IgG amongst the samples received from females was approximately 2.5-fold higher than samples received from males (2.4%). Anti-HEV IgG was detected amongst 7% of animal husbandry workers and amongst 2% of veterinarians and butchers. The current findings represent the first records of HEV surveillance in Cyprus. We investigated the seroprevalence of anti-HEV by monitoring IgG and IgM virus antibodies amongst employees.

High Genetic Diversity among Stenotrophomonas maltophilia Isolates from Single Hospital: Nosocomial Outbreaks or Genotypic Profile Changes during Subcultures.

BACKGROUND: Stenotrophomonas maltophilia is a non-fermentative gram-negative bacillus which is widely recognised as an important nosocomial pathogen causing pneumonia, blood-stream, wound and urinary tract infections, particularly in immunosuppressed patients. The aim of this study was to evaluate a nosocomial outbreak of by S. maltophilia in an intensive care unit of a tertiary hospital and evaluate unexpected multiclonality. METHODS: A total of 11 isolates from respiratory cultures in intensive care unit of a 24 bed tertiary hospital obtained over a one months period and one isolate obtained from the nebuliser during environmental screening were investigated. The bacteria were identified by Phoenix 100 system. The clonal relatedness was evaluated by PFGE and semi-automated repetitive sequence-based PCR. Genotyping tests were repeated for 10 serial subcultures. RESULTS: PFGE and DiversiLab yielded 10 genotypic profiles for 12 isolates. Four to eight different genotypes were observed from 10 subcultures of the same isolate. CONCLUSION: We conclude that, high genetic diversity and supposed multiclonal appearance of the outbreak isolates may be due to changing profiles during subcultures most probably depending on hypermutation.

Effectiveness of non-fluoride and fluoride dentifrices for denture hygiene.

OBJECTIVE: To compare the effectiveness of commonly used herbal/non-fluoride with fluoride dentifrices in order to eliminate pathogenic oral microorganisms from denture base material. MATERIALS AND METHODS: Heat-polymerized acrylic resin specimens (n = 288) were divided into three groups and each group inoculated with three various microorganisms (n = 96 for each) Candida albicans, Staphylococcus aureus and Pseudomonas aeruginosa (P. aeruginosa). Contaminated specimens were randomly assigned to the application of six herbal/non-fluoride and three fluoride dentifrices. These specimens were divided into two groups: negative and positive control (n = 3 for each). All acrylic specimens were incubated at 37 °C for 24 h for samples inoculated with bacterial strains and 37 °C for 48 h for samples inoculated with yeast strains. After the incubation period, all brain-heart infusion broths that contained disinfectant acrylic specimens were cultured on 5% sheep blood agar for bacterial counts and Sabouraud dextrose agar for yeast counts. The number of colony-forming units per millilitre (CFU/mL) were calculated. The results were analysed by Mann-Whitney U and Kruskal-Wallis tests (p = .05). RESULTS: Both herbal/non-fluoride and fluoride dentifrices were effective against Candida albicans. However, fluoride dentifrices were comparatively better than the herbal/non-fluoride dentifrices against Staphylococcus aureus and P. aeruginosa. CONCLUSIONS: Herbal dentifrices could be used, especially among the elderly who lack a degree of manual dexterity during the rinsing of dentifrice chemicals from their dentures.

[Investigation of the correlation between anti-HCV levels (S/Co) with HCV-RNA in the diagnosis of hepatitis C virus (HCV) infection]. / Hepatit C virus (HCV) enfeksiyonunun tanisinda anti-HCV düzeyi (S/Co) ile HCV-RNA arasindaki korelasyonun arastirilmasi.

Detection of borderline and/or low positive anti-HCV results by enzyme immunoassay (EIA) leads to severe problems in routine laboratories and needs confirmation with nucleic acid amplification tests which can increase the cost. In EIA tests, if the ratio of sample to cut-off (S/Co) is ≥ 1, the sample is accepted as positive according to the manufacturers' instructions. Although over the last decade the application of S/Co values have also applied to HCV-RNA readings, the current study aims to determine whether the S/Co value is adequate and applicable for the anti-HCV EIA test, and to determine whether a correlation exists between HCV-RNA and HCV infections. A total of 658 cases (402 female, 256 male; mean age: 49.4 ± 17.0 years) who were found anti-HCV positive between January 2011-July 2013 were included in the study. Anti-HCV tests were performed by chemiluminescent EIA (Architect i2000SR, Abbott, USA and LiaisonXL Murex, DiaSorin, Italy) and HCV-RNA by real-time PCR (Cobas Ampliprep/Cobas TaqMan HCV, Roche, USA). The mean S/Co value of the cases was 7.3 ± 4.8 (range: 1.00-17.59) and mean HCV-RNA value was 2.3x105 ± 2.1x106 copies/ml. When the anti-HCV S/Co value of varying ranges was compared with HCV-RNA readings a particular trend was noted. In the anti-HCV S/Co values of 1.0-4.0; 4.1-7.0; 7.1-10.0; 10.1-13.0; 13.1-16.0 and ³16.1, HCV-RNA positivity rates were detected as 1.9%, 24.7%,37.1%, 46.7%, 56.4% and 75%, respectively. Statistical analysis indicated an intermediate positive correlation (r= 0.454) between anti-HCV ve HCV-RNA readings (p= 0.000). An adequate S/Co value was accepted as 5.0 based on the ROC analysis, and this value gave a performance confidence level of 95.6% when determining whether a patient is HCV positive. Based on the data of this study it became evident that further EIA testing is not required if the S/Co value is ≥ 5.0, however if the S/Co value is less than 5.0, then further clinical analysis and revaluation of the patient is required.

Evaluating the efficiency of humic acid to remove micro-organisms from denture base material.

OBJECTIVE: To evaluate the efficiency of humic acid substances on removing micro-organisms from denture base materials. BACKGROUND: Old denture wearer needs effective, easy-use and safe denture-cleaning material. MATERIAL AND METHODS: Square-shaped, heat-polymerised acrylic resin specimens (n = 550) were prepared and divided into five groups (n = 110 for each) corresponding to the microbial contamination (Candida albicans, Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, Pseudomonas aeruginosa). Contaminated specimens were randomly assigned to the application of five different denture-cleaning agents as follows (n = 20 for each): Kloroben, Corsodyl, Steradent, Corega, experimental solution with humic acid. Ten specimens were assessed as an experimental control carried out simultaneously for the treatment groups for each micro-organism. It was divided into two groups: negative control and positive control (n = 5 for each). All acrylic specimens were incubated 37°C for 24 h (for bacterial strains) and 37°C for 48 h (for yeast strains). After incubation period, all brain-heart infusion broths (BHI) which contain disinfectant acrylic specimens were cultured on 5% sheep blood agar (for bacteria) and Sabouraud dextrose agar (SDA) for yeast using loop. The numbers of colony-forming units per millilitre (CFU/ml) were calculated. The results were analysed by Mann-Whitney U-test and Kruskal-Wallis tests (p = 0.05). RESULTS: Corsodyl and Kloroben completely eliminated the adherence of all investigated micro-organisms (100%) and showed the highest removal activity compared with other cleaning agents (p < 0.05). There was no statistically significant difference between Corsodyl and Kloroben (p ≥ 0.05), and there was no statistically significant difference between Corega, Steradent and experimental solution (p ≥ 0.05). CONCLUSION: Humic acid could be used as an alternative 'natural' solution for denture-cleaning agent.