[Comparison of Three Different Methods in Investigating the Molecular Epidemiology of Carbapenem-Resistant Acinetobacter baumannii Clinical Isolates]

The aim of the study was to evaluate the relationship between carbapenem-resistant Acinetobacter baumannii isolates carrying oxacillinase-type carbapenemase genes with "international high-risk clones" (IC I, II, and III) by different molecular epidemiological methods and to statistically compare the concordance and discrimination power of the methods. Carbapenem-resistant and moderately susceptible A.baumannii isolates from non-repeating blood cultures of 72 patients were included in the study. The presence of "blaOXA-23 , blaOXA-24 , blaOXA-51 ve blaOXA-58 " genes within OXA-type carbapenemases was detected by polymerase chain reaction (PCR) method and confirmed by DNA sequence analysis. Pulsed f ield gel electrophoresis (PFGE), multilocus sequence typing (MLST) and matrix-assisted laser desorption/ ionization time- of-flight mass spectrometry (MALDI-TOF MS) analyses were performed to evaluate the clonal relations of IC I, II and III clones together with clinical isolates. In the statistical comparison of the methods, discrimination power was evaluated by Simpson index of diversity (SID) and concordance by "Wallace coefficient". All of the isolates were found to carry blaOXA-23 and blaOXA-51 genes. As a result of the bioinformatic analysis of the four isolates selected for sequence analysis; blaOXA-23 and blaOXA-51 genes were detected in the selected isolates, and the analysis of two isolates carrying blaOXA-51 gene showed 99% similarity with blaOXA-92 gene. The isolates were clustered into five pulsotypes (A, B, C, D and E) according to ≥ 85% similarity coefficient by PFGE. The isolates and RUH 875, RUH 134, LUH 5875 strains belonging to high-risk clones ICI, ICII and ICIII, respectively, were divided into five main groups [A (n= 58), B (n= 8), C (n= 4), D (n= 4) and E (n= 1)] and 10 subgroups (A1, A2, A4, A5, A6, A9, B1, B4, C3, D1) by PFGE. IC clone III (E1) and seven strains showed singleton PFGE profiles (A3, A7, A8, B2, B3, C1, C2). ICII was found in A5 subtype, ICI in C1 subtype and ICIII in E1 subtype. By PFGE subtype groups, 18 pulsotypes were determined and ST1, ST2, ST81, ST157 and ST604 sequence types were found in 20 isolates randomly selected from pulsotypes according to MLST Pasteur scheme (cpn60, fusA, gltA, pyrG, recA, rplB, rpoB). Principal component analysis (PCA) of the spectra of 72 A. baumannii isolates and ICI, ICII and ICIII clones was performed by MALDI-TOF MS. In PCA analysis, the cluster distance level was defined as 1.5 and the isolates were divided into three clusters. IC clone I, II and III together with 70 clinical isolates were grouped in one cluster, while two clinical isolates (AB083 and AB0115) formed singleton clusters. There was no significant agreement between MALDI-TOF MS; MLST and PFGE data according to Wallace coefficient. It was found that PFGE method gave significant results in terms of discrimination power with SID coefficient, MALDI-TOF MS PCA analysis had the lowest discrimination power value, and the Wallace coefficient result of PFGE and MLST was concordant. In conclusion, MALDI-TOF MS may not function as a gold standard method like PFGE and MLST for epidemiological analysis in A.baumannii species and the epidemiological typing protocols used for MALDI-TOF MS need to be improved and developed.

Neutralization of Wild-Type and Alpha SARS-CoV-2 Variant by CoronaVac® Vaccine and Natural Infection- Induced Antibodies

One of the immune responses desired to be achieved by SARS-CoV-2 vaccination is to create neutralizing antibodies (nAbs), thus preventing the development and spread of infection. The aim of this study was to investigate the seropositivity rate, anti-spike antibody levels, and neutralizing capacity of these antibodies against wild type (WT) and alpha variants in serum samples of individuals who had been naturally infected or vaccinated with CoronaVac®. Total anti-spike antibody levels were determined in all samples. Neutralization assays were performed by the reduction of the cytopathic effect in Vero-E6 cells with infectious WT and alpha SARS-CoV-2 variants. Although both naturally infected and vaccinated individuals were all seropositive for antispike antibodies, 84.8% of the vaccinated group, and 89.3% of the naturally infected group had detectable nAbs. The nAbs titers were significantly higher in the naturally infected group for both WT and alfa variant of the virus as compared to the vaccinated individuals. In this study, it was observed that all individuals became seropositive six weeks after exposure to the vaccine or the virus. Moreover, naturally infected individuals had higher levels of nAbs than those vaccinated. The presence of nAbs against the alpha variant in both naturally infected and vaccinated individuals suggests that these antibodies may also be protective against infections, which may be caused by other variants, such as delta and omicron.

Identification and antifungal susceptibility of Saprochaete clavata from invasive infections in Turkey

Saprochaete clavata is an emerging opportunistic pathogen, that causes life-threatening infections, but there are limited evidence and information about the evaluation of in vitro antifungal susceptibility test results. The aim of this study was to determine S. clavata isolates from clinical specimens and to investigate their in vitro antifungal susceptibility. S. clavata was identified by API ID20C AUX (BioMérieux, Brussels, Belgium), MALDI TOF (Bruker Daltonik, Germany), and ITS gene region sequencing. In vitro susceptibility tests were performed using Sensititre YeastOne (TREK Diagnostic System, East Grinstead, UK). During the study period, 4,736 fungi were isolated from various clinical samples and, S. clavata was identified in eight patients with underlying diseases namely, pancreatic neoplasma, acute myeloid leukaemie, follicular lymphoma, cholelithiasis. Anidulafungin and micafungin minimum inhibitory concentration values were 1-2 and 1-4 mg/L, respectively, while those of the azole group antifungals were much lower. This is the first study in Turkey reporting isolation, identification and antifungal susceptibilities of S. clavata from clinical specimens. Higher MIC values seen in some isolates suggest that continuous monitoring of sensitivity rates and observation of regional differences will thus be useful guides in determining infection control and antifungal use policies.

[Investigation of Plasmid Mediated mcr Colistin Resistance Gene in Clinical Enterobacterales Isolates]

Carbapenems are used in the treatment of infections caused by multidrug-resistant bacteria and colistin (polymyxin E) is used as the last choice of antimicrobial agent in those resistant to carbapenems. The worldwide and increased use of colistin, which causes cell death by disrupting the permeability of the cytoplasmic membrane of gram-negative bacteria, raised the problem of resistance. The transferable colistin resistance enzyme mcr, is a phosphoethanolamine transferase that adds phosphoethanolamine to lipid A and modifies lipopolysaccharides, leading to polymyxin resistance. The aim of this study was to investigate some of the most prevalent plasmid mediated colistin and carbapenemase resistance genes in colistin resistant Enterobacterales isolates. Enterobacterales isolates which were isolated in the samples of patients treated in the clinical units between October 2016 and September 2018 in the Karadeniz Technical University Faculty of Medicine Farabi Hospital Medical Microbiology Laboratory were included in the study. In addition to conventional methods, isolates were identified to the species level by MALDI-TOF MS (Bruker Daltonics, Germany). The antibiotic susceptibilities of Enterobacterales isolates were studied by an automated microbiology system (Phoenix, Becton Dickinson, USA) and evaluated according to European Committee on Antimicrobial Susceptibility Testing (EUCAST) criteria. In isolates that are resistant to colistin, and the isolates that are found to be sensitive but should be included in the patient report of the colistin susceptibility test, colistin susceptibility tests were repeated with liquid microdilution method in accordance with EUCAST standards. The presence of extended spectrum beta-lactamase (ESBL), AmpC beta-lactamase and carbapenemase were determined by phenotypic methods according to EUCAST recommendations in colistin resistant Enterobacterales isolates. Furthermore, resistance genes of mcr-1-5, blaOXA-48, blaKPC, blaNDM, blaVIM, blaIMP were detected by polymerase chain reaction (PCR) method, followed by nucleotide sequence analysis of the amplified products. In our study, 14657 Enterobacterales isolates belonging to 7535 patients treated in different clinical units were examined retrospectively. Escherichia coli 61.2% (n= 8968), Klebsiella pneumoniae 22.7% (n= 3334) and Enterobacter cloacae 6.9% (n= 1005) were the most prevalent isolates. Carbapenem resistance was detected in 894 isolates, and 5.8% (n= 412) of 7135 isolates isolated between October 2016 and September 2017; 6.4% (n= 482) of 7522 isolates between October 2017 and September 2018 were found to be resistant. Considering all isolates, colistin resistant isolates were 65 (0.9%) between October 2016 and September 2017 and 97 (1.3%) between October 2017 and September 2018. By including only the first isolates in the study for the same agent growths in different samples of the same patient, 46 colistin resistant isolates were selected. Six isolates which could not be cultivated from stock cultures were excluded from the study material. Thirteen (32.5%) of the 40 colistin resistant Enterobacterales isolates were isolated in 2017 and 27 (67.5%) were isolated in 2018. ESBL was detected in 22, AmpC beta-lactamase was detected in 6, carbapenem resistance was detected in 15 of them by phenotypic methods. As a result of PCR analysis, mcr-1 gene detected in 2 isolates, blaOXA-48 in 2 isolates, blaVIM in 1 isolate, blaKPC and blaOXA-48 in 1 isolate, blaNDM and blaOXA-48 in 5 isolates. These results were confirmed by sequencing of the PCR products. The mcr-1 genes were found in E.coli isolates grown in urine culture samples of 2 women over 65 years of age treated in our hospital. Among the antibiotics tested, only ampicillin resistance was observed in 1 of the patients, whereas ampicillin, amoxicillin-clavulanate and ciprofloxacin resistance were detected in the other. In conclusion, as far as we can reach in the literature our publication is the first study showing the presence of mcr-1 gene in clinical samples in our country and confirmed by DNA sequence analysis. The detection of mcr gene in isolates without multidrug resistance showed once again the importance of colistin susceptibility testing in the laboratories. In addition, the presence of isolates containing more than one resistance genes in our study, suggests that the spread of carbapenem and colistin resistance may be faster than expected.

Determination of Seroprevalence of Borrelia burgdorferi IgG in Adult Population Living in Trabzon

BACKGROUND

Lyme borreliosis is a tick-borne, multi-systemic infectious disease that is thought to be wide spread in Turkey even though studies on its seroprevalence are limited.

AIMS

To determine the seroprevalence of Lyme borreliosis in part of north-eastern Tur-key (in the city of Trabzon), and to identify possible relationships between seropositivity and various factors such as location, gender, age group, occupation, income, and educational level.

STUDY DESIGN

Retrospective cross-sectional study.

METHODS

A total of 884 blood samples collected from provincial and district health centers serving a population of about 800,000 were included in this study. ELISA was used to determine the anti-Borrelia IgG antibody levels in the samples. Samples that yielded positive results by ELISA were further subjected to western blot (WB).

RESULTS

IgG antibodies were found in 128 samples (14.5%). Statistical analysis revealed significant differences between age groups and educational levels in terms of the incidence of seropositivity, whereas location, gender, occupational group and income level had no effect (p<0.001, p<0.001, p=0.948, p=0.645, p=0.131, p=0.080 respectively).

CONCLUSIONS

The risk of contracting Lyme borreliosis in Trabzon is high, and necessary measures need to be taken to avoid the spread of disease.