Talaromyces marneffei infection in an HIV infected patient with hematological malignancy - first report from Turkey.

T.marneffei, encountered mostly in Southeast Asia, leads to a systemic infection, especially in immunocompromised individuals such as HIV-infected patients with low CD4 level. A 32-year-old male patient, residing in Hong Kong for the last two years, admitted with fever, cough, weakness, and weight loss. Physical examination revealed bilateral cervical and axillary multiple lymph nodes and hepatosplenomegaly. Screening of the pancytopenic patient revealed HIV infection. Histopathological examination of the cervical lymph node revealed plasmoblastic lymphoma. Blood and urine cultures remained sterile. Antiretroviral therapy was started. Fungal hyphae were detected in Gram staining of hemocultures taken in the third week due to ongoing fever, and antifungal therapy was started empirically. Red pigment around colonies on Sabouraud dextrose agar and microscopic appearance arose suspicion of Talaromyces spp. T.marneffei was identified by ITS 1-4 sequence analysis. Chemotherapy was started when fungemia was controlled. On the fifth day of chemotherapy, the patient's general condition deteriorated, broad-spectrum antibiotics were started and the patient was transferred to ICU. The cultures remained sterile and he expired five days later. In conclusion, although talaromycosis is not endemic in Turkey, it should be considered in patients with travel history to endemic regions and/or an underlying immunosuppressive disease such as HIV infection.

Incidence, Risk Factors, and Prognosis of Bloodstream Infections in COVID-19 Patients in Intensive Care: A Single-Center Observational Study.

BACKGROUND: Critically ill COVID-19 patients are prone to bloodstream infections (BSIs). AIM: To evaluate the incidence, risk factors, and prognosis of BSIs developing in COVID-19 patients in the intensive care unit (ICU). METHODS: Patients staying at least 48 h in ICU from 22 March 2020 to 25 May 2021 were included. Demographic, clinical, and laboratory data were analyzed. RESULTS: The median age of the sample (n = 470) was 66 years (IQR 56.0-76.0), and 64% were male. The three most common comorbidities were hypertension (49.8%), diabetes mellitus (32.8%), and coronary artery disease (25.7%). Further, 252 BSI episodes developed in 179 patients, and the BSI incidence rate was 50.2 (95% CI 44.3-56.7) per 1000 patient-days. The source of BSI is central venous catheter in 42.5% and lower respiratory tract in 38.9% of the episodes. Acinetobacter baumannii (40%) and carbapenem-resistant Klebsiella pneumoniae (21%) were the most common pathogens. CRP levels were lower in patients receiving tocilizumab. Multivariable analysis revealed that continuous renal replacement therapy, extracorporeal membrane oxygenation, and treatment with a combination of methylprednisolone and tocilizumab were independent risk factors for BSI. The estimated cumulative risk of developing first BSI episode was 50% after 6 days and 100% after 25 days. Of the 179 patients, 149 (83.2%) died, and a statistically significant difference (p < 0.001) was found in the survival distribution in favor of the group without BSI. CONCLUSION: BSI is a common complication in COVID-19 patients followed in the ICU, and it can lead to mortality. Failure in infection control measures, intensive immunosuppressive treatments, and invasive interventions are among the main factors leading to BSIs.

Association of SARS-CoV-2 IgG Antibody Levels with Clinical/Laboratory Characteristics in COVID-19 Patients: Data from a Turkish Study.

BACKGROUND: COVID-19 causes clinical manifestations ranging from asymptomatic infection to multi-organ failure. It is reported that those with severe disease have higher anti-SARS-CoV-2 antibody titers compared to asymptomatic or mild cases. We evaluated the correlation of antibody responses with laboratory and clinical indicators in COVID-19 patients. METHODS: Seventy-nine male and 66 female patients (mean age: 39) with at least one positive SARS-CoV-2 RT-PCR test and SARS-CoV-2 IgG antibody result after acute infection were included. RESULTS: Seventy-six (52%), 45 (31%), and 24 (17%) patients had mild, moderate, and severe clinical findings, respectively. Patients with high body mass index and advanced age had significantly more severe disease (p < 0.001). A significant correlation was found between the increase in lymphopenia, C-reactive protein, ferritin, D-dimer, and lactate dehydrogenase and the severity of clinical findings (p = 0.0001). SARS-CoV-2 IgG antibody test was positive in 128 (88.3%) patients. A significant correlation was found between disease severity and antibody levels in the comparison of all groups (p < 0.001). CONCLUSIONS: Long-term monitoring of immune responses will be required to determine the appropriate time for the administration of new vaccines.

A pan-resistant Myroides odoratimimus catheter-related bacteremia in a COVID-19 patient and review of the literature.

Myroides spp. are opportunistic environmental Gram-negative bacteria. These affect mostly immunocompromised hosts and generally lead to soft tissue, and urinary tract infections. Bacteremia most commonly develop secondary to soft tissue or catheter related infections and may lead rarely to mortality. Myroides spp. are generally suscetible to fluoroquinolones, piperacillin/tazobactam, trimethoprim/sulfamethoxazole, carbapenems or tetracyclines however, pan-resistant isolates and multiple resistance genes have been reported in clinical isolates of Myroides spp. We report a pan-resistant Myroides odoratimimus bacteremia in a patient with severe COVID-19 ending with fatality and in this context a review of reported Myroides bacteremias are also described. In this study, a 64-year old male patient with history of coronary artery bypass was admitted to ICU with severe COVID-19 pneumonia accompanied by pneumomediastinum and pneumopericardium. Continous renal replacement therapy and extracorporeal membraneous-oxygenation were initiated due to acute renal failure and persistent hypercarbia/hypoxia, respectively. Within four weeks of hospitalization various episodes of bacteremia developed and multiple antibiotics were used. On the 5th week of follow-up, acute phase reactants increased and empirical broad spectrum antibiotics were initiated. Blood culture revealed Gram-negative rods. The patient became hypotensive and despite maximum medical care he was lost due to cardiac arrest. M. odoratimimus was identified by MALDI-TOF and the bacterium was pan-resistant. According to Center for Genomic Epidemiology results the strain was identified as M. odoratimimus PR63039 and the genome analysis revealed antibiotic resistance genes associated with resistance to beta-lactams (bla OXA-347, bla MUS-1, bla EBR-1), tetracyclines (tetX), sulfonamides (sul2), macrolides (ereD), (ermF).

The effect of methotrexate monotherapy on treatment-resistant idiopathic granulomatous mastitis patients.

BACKGROUND: Idiopathic granulomatous mastitis (IGM) is a disease of unknown etiology, involving a chronic inflammatory process, characterized by noncaseating granuloma formation. IGM can mimic a tumor clinically and radiologically. Since we are a tertiary referral center, most of our patients (n = 56, 87.5%) are secondary admissions who have previously had antibiotics and steroid treatments; therefore, we accept these patients as resistant cases. Here, we aim to present our single-center series of 64 patients with resistant IGM who underwent methotrexate monotherapy. To the best of our knowledge, our study includes the highest number of patients described in the literature with IGM who have undergone this treatment. METHODS: This study included 64 patients, 56 of which were resistant cases, diagnosed with IGM between January 2013 and January 2020 at Istanbul University Cerrahpasa, Cerrahpasa Medical Faculty, General Surgery Breast Outpatient Clinic that were followed-up at least once. These patients were administered oral methotrexate monotherapy 15 mg/week for 24 weeks, and in relapsed cases, the treatment was up to 20 mg/week for 1 year. Folic acid 10 mg/week was given as a supplement to all patients. RESULTS: Complete recovery was observed in 52 (81.25%) of the 64 patients. Follow-up was discontinued by 4 patients. The dose was increased and the duration of treatment was extended up to 1 year when relapse was observed in 8 patients and complete response was then obtained in these cases. Only 3 patients (4.69%) experienced side effects and were switched to subcutaneous treatment due to nausea. CONCLUSION: Considering the high patient compliance, low recurrence, minimal side effects, and overall success of the treatment, we believe that methotrexate monotherapy may be used in treatment-resistant IGM patients and may also be the first choice for first-line treatment in the future.

Colistin resistance increases 28-day mortality in bloodstream infections due to carbapenem-resistant Klebsiella pneumoniae.

Mortality due to K. pneumoniae bacteremia is on rise, particularly in regions with high rates of carbapenem and colistin resistance. We aimed to define risk factors for colistin resistance and its impact on mortality. Patients diagnosed with "carbapenem-resistant K. pneumoniae (CRKp)" bacteremia between 2014 and 2018 were divided into two groups as "colistin susceptible (ColS)" and "colistin resistant (ColR)" based on broth microdilution method. Retrospective case-control study was conducted to compare characteristics and outcomes. Multiple logistic regression model was used to define independent risk factors for acquired colistin resistance and Cox proportional hazard model for 28-day mortality. A total of 82 patients (39 ColS and 43 ColR) were included. Mean age was 61.5 years, and 50 (61%) were male. Colistin resistance was significantly increased with duration of hospital stay (p = 0.007) and prior colistin use (p = 0.007). Overall, the 28-day mortality rate was 66%. Age (p = 0.014) and colistin resistance significantly increased 28-day (p = 0.009) mortality. Microbiological response to treatment within 7 days favors survival. PFGE analysis revealed an outbreak with K. pneumoniae ST78 and ST45 clones. Patients treated with combined antimicrobials had significantly lower 28-day mortality (p = 0.045) in comparison to monotherapy. However, types of combinations did not show significant superiority on each other. Colistin resistance increases 28-day mortality in CRKp bacteremia. Although combined regimens are more effective than monotherapy, existing antibacterial combinations have no apparent superiority to each other. New treatment options are pivotal.

Change in species distribution and antifungal susceptibility of candidemias in an intensive care unit of a university hospital (10-year experience).

Candidemia is a nosocomial infection mostly found in critically ill patients. Our objectives were to evaluate the change in distribution and resistance profile of Candida spp. isolated from candidemic patients in our intensive care unit over two 5-year periods spanning 15 years and to evaluate the risk factors. Records from the microbiology laboratory were obtained, from January 2004 to December 2008 and from January 2013 to December 2017, retrospectively. Antifungal susceptibility was performed by E-test and evaluated according to EUCAST breakpoints. A total of 210 candidemia cases occurred; 238 Candida spp. were isolated in 197 patients (58.8% male; mean age, 59.2 ± 19.6 years). The most predominant risk factor was central venous catheter use. Species distribution rates were 32%, 28%, 17%, and 11% for C. albicans (n = 76), C. parapsilosis (n = 67), C. glabrata (n = 40), and C. tropicalis (n = 27), respectively. Resistance rate to anidulafungin was high in C. parapsilosis over both periods and increased to 73% in the second period. Fluconazole showed a remarkable decrease for susceptibility in C. parapsilosis (94 to 49%). The prevalence of MDR C. parapsilosis (6%/33%) and C. glabrata (0%/44%) increased in the second period. We observed a predominance of non-albicans Candida spp., with C. parapsilosis being the most frequent and C. glabrata infections presenting with the highest mortality. High level of echinocandin resistance in C. parapsilosis and increasing prevalences of MDR C. parapsilosis and C. glabrata seem emerging challenges in our institution.

Tocilizumab in COVID-19: The Cerrahpasa-PREDICT score.

BACKGROUND: Cytokine release syndrome (CRS), characterized by overproduction of proinflammatory cytokines in the course of severe coronavirus disease 2019 (COVID-19), has been suggested as the major cause of mortality. Tocilizumab, a recombinant humanized monoclonal antibody against human IL-6 receptor, poses a therapeutic option for the treatment of CRS leading to severe acute respiratory syndrome in coronavirus-2 (SARS-CoV-2) infection. METHODS: We performed a single-center retrospective study to reveal the outcome of COVID-19 patients on tocilizumab and proposed "the Cerrahpasa-PREDICT score", a new clinical scoring system using clinical and laboratory parameters that would help predicting the 28-day mortality of COVID-19 patients receiving tocilizumab. RESULTS: Eighty-seven patients (median age: 59 years) were included of whom 75.8% were male. Tocilizumab use significantly improved clinical and laboratory parameters. The 28-day mortality rate on tocilizumab was 16.1%. The Cerrahpasa-PREDICT score, consisting of platelet counts, procalcitonin, D-dimer levels, SO2R and the time from symptom onset to tocilizumab administration had a positive predictive value of 94.5% and negative predictive value of 92.9% for anticipating 28-day mortality. CONCLUSIONS: Severe COVID-19 should closely be monitored for the signs of hyperinflammation. We showed that administration of tocilizumab early in the course of the disease (prior to ICU admission) resulted in a favorable outcome. Close monitoring usually aids identifying patients who would benefit from tocilizumab. In this regard, the Cerrahpasa-PREDICT score might serve as a practical tool for estimating the 28-day mortality in COVID-19 patients who received tocilizumab and would facilitate timely recognition of fatal cases to be evaluated for other therapeutic options.

Clinical and microbiological characteristics of Aeromonas bacteremia in Turkey.

We investigated the cases with Aeromonas bacteremia in terms of clinical and microbiological characteristics, underlying disease and mortality rates. Patients with positive blood cultures were included in this research. Aeromonas bacteremia was diagnosed as at least one positive blood culture for Aeromonas species. The bacteremia was defined as community origin if the onset was in the community or within 72 hours of hospital admission. The others were considered as nosocomial. All bacteria were defined as Aeromonas with conventional method. Species identification was verified by VITEK system. Antibiotic susceptibility tests were analyzed with the disc diffusion, E-test method or VITEK system. Thirty-three patients were diagnosed with bacteremia due to Aeromonas spp. Hematologic and solid tumors were the leading underlying conditions, followed by cirrhosis. Two patients (6%) had community-acquired infections. Aeromonas hydrophila was the most common isolated bacterium. The crude mortality rate was 36%. 12 patients died and 6 deaths and 4 deaths were detected in patients with bacteremia caused by A. hydrophila and Aeromonas sobria respectively. All strains were resistant to ampicillin and more than 90% of the strains were susceptible to trimethoprim-sulfamethoxazole, fluoroquinolone, third generation cephalosporins, and carbapenems. Aeromonas sp. is not a frequent cause of bacteremia however, it may lead to high mortality rates, especially in the immunocompromised hosts and patients with liver cirrhosis. Nosocomial Aeromonas bacteremia is not uncommon in these populations. Broad-spectrum cephalosporins, piperacillin-tazobactam, fluoroquinolones, and carbapenems remain as effective antimicrobial agents for therapy of Aeromonas bacteremia.

COVID-19 and Plasmodium ovale Malaria: A Rare Case of Co-Infection.

The COVID-19 pandemic continues to be a major health problem worldwide. Timely diagnosis of co-infections mimicking COVID-19, such as malaria, might be challenging particularly in non-endemic areas. We report the first case of COVID-19 and Plasmodium ovale malaria co-infection from our region aiming to highligt the importance of travel history and prophylaxis in malaria management in the context of pandemic. The galloping sound can sometimes be a harbinger of zebra besides the horse.

An eleven-year cohort of bloodstream infections in 552 febrile neutropenic patients: resistance profiles of Gram-negative bacteria as a predictor of mortality.

Antimicrobial stewardship is of major importance in patients with febrile neutropenia (FN). In this study, we aimed to investigate the trends in resistance and the relationship with mortality rates in patients with FN. The single-center surveillance data of inpatients with FN and diagnosed as microbiologically confirmed bloodstream infections (BSIs) between 2006 and 2016 were reviewed retrospectively. A total of 950 episodes in 552 patients with BSIs were analyzed. Of whom, 55.9% were male, the median age was 43 years, and 35.6% had acute myeloid leukemia. In total, 1016 microorganisms were isolated from blood cultures. Gram-negatives accounted for 42.4% (n = 403) of the episodes. Among Gram-negatives, Enterobacteriaceae accounted for 346 (86%) (E. coli, n = 197; 34% extended-spectrum ß-lactamases (ESBL) producers, and Klebsiella spp., n = 120; 48.3% ESBL producers). Also, 24 (20.0%) of Klebsiella spp. had carbapenemase activity. There were 6 (5.0%) colistin-resistant Klebsiella spp. Thirteen (26.5%) of Pseudomonas spp. and 17 (60.7%) of Acinetobacter spp. had carbapenemase activity. There were 2 (5.6%) colistin-resistant Acinetobacter spp. The 30-day mortality rates were 12.0%, 21.5%, 34.6%, and 29.0% in BSIs due to Gram-positive, Gram-negative bacterial, fungal, and polymicrobial etiology respectively (p = 0.001). BSIs with ESBL-producing (p = 0.001) isolates, carbapenem (p < 0.001), and colistin-resistant isolates (p < 0.001) were associated with increased mortality risk. The tremendous rise in resistance rates among Gram-negatives is dreadfully related to increasing mortality and leads to sharp shifts toward extreme restrictions of unnecessary antibiotic uses. Antimicrobial stewardship in patients with FN requires vigilance and tailoring of treatment upon local surveillance data.

Late presentation among patients with human immunodeficiency virus infection in Turkey.

OBJECTIVE: Late presentation of the patients with human immunodeficiency virus (HIV) infection is associated with less favourable treatment responses, more accelerated clinical progression, and a higher mortality risk. Although HIV prevalence is low in Turkey, it is steadily increasing and the information about late presentation among HIV-positives is limited. We aimed to analyze the status of late presentation among HIV-positive patients in Turkey. METHODS: All newly diagnosed HIV/AIDS patients from 2003 to 2016 were enrolled in this study by five dedicated centres in Istanbul, Turkey. Demographic data, CD4+ counts, and HIV RNA were collected from medical records and were transferred to a HIV database system. Late pre- sentation was defined as presentation for care with a CD4 count < 350 cells/mm3 or presentation with an AIDS-defining event, regardless of the CD4 cell count. A medical literature search was done for the analysis of late presentation in Turkey. RESULTS: The cohort included 1,673 patients (1,440 males, median age 35 years). Among them, 847 (50.6%) had an early diagnosis, with a CD count of more than 350 cells/mm3. The remaining 826 were late presenters. Among late presenters, 427 (25.5% of all, 51.7% of late presenters) presented with advanced HIV disease. Late presenters were more elderly and less educated. The gender seemed comparable between groups. Late presentation was more likely among married patients. Early presenters were more likely among homosexuals, those diagnosed in screening studies, and in lower HIV-RNA viral load category. There has been a decreasing trend among late presenters in 2011-2016 when compared to 2003-2011 period. CONCLUSION: Current data suggest that half of HIV-infected patients present late in Turkey. In our cohort, those presented late were more elderly, less educated, married and had heterosexual intercourse. On admission, late presenters had more HIV-related diseases and were more likely in higher HIV-RNA category. In the cohort, men having sex with men were less likely late presenters. Efforts to reduce the proportion of late presentation are essential for almost every country. The countries should identify the risk factors of late presentation and should improve early diagnosis and presentation for HIV care.

Urinary tract infections in older adults: associated factors for extended-spectrum beta-lactamase production.

Objective: Urinary tract infections (UTIs) due to extended-spectrum beta-lactamase (ESBL) producing Escherichia coli and Klebsiella pneumoniae are among the leading causes of morbidity and mortality in older adults. Identifying associated factors for ESBL production may contribute to more appropriate empirical treatment. Materials and methods: This was a prospective observational study. Hospitalized patients of age > 65 with community-onset or hospital-acquired upper UTI due to E. coli or Klebsiella pneumoniae were included. A multivariate analysis was performed. Results: A total of 97 patients were included. ESBL prevalence among UTIs with E. coli or Klebsiella pneumoniae was 69.1% (n = 67). CRP values at the time of UTI diagnosis were found to be significantly higher in the ESBL-producing group (p = 0.004). The multivariate analysis revealed that male gender (OR: 2.72, CI: 1.02-7.25), prior recurrent UTI (OR: 3.14, CI: 1.21-8.14), and the development of secondary bacteremia (OR: 4.95, CI: 1.03-23.89) were major associated factors for UTI in older adults due to ESBL-producing E. coli and Klebsiella pneumoniae. Conclusion: Severe UTI in older men with a history of recurrent UTI may be a warning to the clinician for ESBL production in the setting of high ESBL prevalence. Carbapenems may be prioritized in the empirical treatment of patients with known risk factors for ESBL.

Frequency of Human Leukocyte Antigen-B*57:01 Allele Carriers in People Living with HIV/AIDS in Türkiye.

INTRODUCTION: Abacavir is among the first-line initial antiretroviral regimens for most patients living with HIV/AIDS (PLWHA). Although well tolerated, it is associated with hypersensitivity reaction (HSR), which is treatment-limiting and potentially life-threatening. HSR was shown to be associated with the class I MHC allele, HLA-B*57:01. In this study, we aimed to evaluate the prevalence of HLA-B*57:01 in PLWHA in Istanbul, Türkiye. MATERIAL AND METHODS: Five HIV treatment centers in Istanbul included all sequential treatment-- naïve, ≥ 18 years adult PLWHA, between December 2017- December 2021. Demographic, clinical, and laboratory data were collected at baseline and during treatment. HLA-B* 57:01 genotyping was determined with PCR-SSP. RESULTS: Eight hundred sixty-seven PLWHA were included (male:91%, mean age 39.6±11.1 years). 1.6% of patients were found to be HLA-B*57:01 positive. Among HLA-B*57:01 positive patients, 4 were initially given abacavir-containing treatment; they were switched to non-abacavir treatment upon the allele found to be positive. CONCLUSION: Although previous studies reported the HLA-B*57:01 prevalence of PLWHA in Türkiye as 3-3.6%, we have found the prevalence to be 1.6%. The current study includes higher numbers of patients than the previous studies. Furthermore, patients from all over the country apply to the centers in Istanbul; compared to the other studies, which involve patients limited to the relevant regions, it can be assumed that the number in our cohort is more representative of the country. In conclusion, the prevalence of the HLA-B*57:01 allele in PLWHA in this study is relatively low. With evident benefit in preventing abacavir HSR, HLA-B*57:01 should be screened in planning antiretroviral therapy.

Bone Metabolism in Men who Live with HIV Aged 50 years and Over: Impact of Infection Duration.

BACKGROUND: Early diagnosis and effective antiretroviral therapy (ART) lead to similar life expectancy in people living with HIV (PLWH) compared to the general population. This population faces problems such as decreased bone mineral density (BMD) and increased fracture risk. The aim of this study was to determine the prevalence of osteoporosis in men aged 50 years and over who were PLWH and to determine risk factors and changes in bone metabolism with bone turnover markers. METHODS: 79 male PLWH aged 50 years and over were followed up in our outpatient clinic between May 2021 and October 2021. The patients' demographic, clinical, laboratory, and DEXA data were analyzed. Serum levels of bone turnover markers were measured. RESULTS: The prevalence of osteopenia, osteoporosis, and normal BMD was found to be 55.7%, 13.9%, and 30.4%, respectively. A correlation was found between low BMD and low body mass index, elapsed time since diagnosis of HIV infection, high rate of use of ART, and long usage time of tenofovir disoproxil fumarate + protease inhibitor. A one-year increase in HIV infection duration was associated with an increased risk of low BMD by 1.246. CONCLUSION: Compared to studies conducted on the general population, the prevalence of osteoporosis in male PLWH aged 50 years and older was two times higher. The limited effect of the duration of ART use on low BMD may be due to the patients' histories of replacement therapy. Therefore, to eliminate the negative effects of ART on BMD, it may be beneficial to start replacement therapy when necessary.

Port-related Delftia tsuruhatensis bacteremia in a patient with breast cancer.

Delftia tsuruhatensis is a non-glucose fermenting, oxidase positive, motile, gram-negative bacillus first isolated from activated sludge collected from a domestic wastewater treatment plant in Japan. To the best of our knowledge only one case of infection with Delftia tsuruhatensis exists in the medical literature. This is the second case report of human infection having Delftia tsuruhatensis as a causative agent.

Ecthyma Gangrenosum-like Lesions in a Febrile Neutropenic Patient with Simultaneous Pseudomonas Sepsis and Disseminated Fusariosis.

UNLABELLED: Fusarium spp. is an opportunistic mold that causes disseminated infections in immunocompromised patients. It is important to make a definite diagnosis because of high mortality rates. We present the case of a 27-year-old pregnant woman diagnosed with acute myeloid leukemia with a prolonged febrile neutropenic period. She developed ecthyma gangrenosum-like lesions and simultaneously had Pseudomonas bacteremia and disseminated fusariosis. Histopathological and microbiological features of skin lesions had a critical role in differential diagnosis. Ecthyma gangrenosum-like lesions due to disseminated fusariosis might be easily misdiagnosed as lesions associated with Pseudomonas unless tissue cultures and histopathological examinations are performed. CONFLICT OF INTEREST: None declared.

Waning immunity to inactive SARS-CoV-2 vaccine in healthcare workers: booster required.

AIMS: Despite high vaccination rates, increasing case numbers continue to be reported with the identification of new variants of concern, and the issue of durability of the vaccine-induced immune response remains hot topic. Real-life data regarding time-dependent immunogenicity of inactivated COVID-19 vaccines are scarce. We aimed to investigate the changes in the antibody at the different times after the second dose of the CoronaVac vaccine. METHODS: The study included 175 HCWs vaccinated with inactive CoronaVac (Sinovac Life Sciences, China) SARS-CoV-2 vaccine in two doses. Anti-spike/RBD IgG levels were measured first, third, and sixth months after the second dose. Chemiluminescent microparticle immunoassay (IgG II Quant test, Abbott, USA), which is 100% compatible with plaque reduction neutralization test, was used. RESULTS: Mean age of the participants was 38 ± 11.23 years (range between 22 and 66) of whom 119 (63.9%) were female, and 56 (32%) were male. Dramatic reductions were demonstrated in median antibody levels particularly in the infection-naïve group, comprising 138 HCWs compared to those with prior history of COVID-19 infection (n = 37) (p < 0.001). There was no difference between the two groups in terms of age, gender, blood groups, BMI, and comorbid diseases. CONCLUSIONS: While antibody positivity remained above 90% in the 6th month after two doses of inactivated vaccine in HCWs, the median titers of neutralizing antibodies decreased rapidly. The decrease was more rapid and significant in those with no history of prior COVID-19 infection. In this critical phase of the pandemic, where we are facing the dominance of the Omicron variant after Delta, booster doses have become vital.