Reinfections from SARS-CoV-2: A Retrospective Study from the Gyncentrum Genetic Laboratory in Sosnowiec, Poland, April 2020 to July 2022.

BACKGROUND The increasing number of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reinfections has opened a new research direction related to analyzing long-term immune response and accurately characterizing individual cases of reinfection to understand its mechanism and estimate the risk of widespread reinfection both locally and globally. This retrospective study from the Gyncentrum Genetic Laboratory in Sosnowiec, Poland aimed to evaluate reinfections from SARS-CoV-2 between April 2020 and July 2022. MATERIAL AND METHODS The study extended the previously published report on SARS-CoV-2 infection cases in Poland by analyzing 8041 reinfections diagnosed with real-time reverse transcription-polymerase chain reaction (RT-PCR) assay. Data were collected on the amount of time elapsed from the first infection to the next and, based on these data, all results were divided into several groups for statistical analysis: 0-44, 45-90, 91-200, 201-310, 311-420, and >420 (days). RESULTS The study showed that of the 8041 patients who experienced reinfection, the vast majority (5505) became reinfected more than 310 days after the original infection, even though the average time between infections was 354.3 days. Statistical analysis revealed that the risk of SARS-CoV-2 reinfection increases with time and that this relationship becomes statistically significant after the 200th day following the initial infection (p<0.01). CONCLUSIONS We have shown that acquired immunity to SARS-CoV-2 infection is relatively short-lived - it starts diminishing about 6 months after the initial positive test. Moreover, the risk of reinfection is very high more than 1 year after the initial infection.

Clinical significance of asymptomatic [i]Clostridium difficile[/i] colonisation in patients undergoing antibiotic treatment.

BACKGROUND: [i]Clostridium difficile[/i] infections become a serious problem in terms of nosocomial infections, as well as a consequence of common use of antibiotics. AIM: The aim of the study was to evaluate [i]Clostridium difficile[/i] carriage in patients admitted to the Clinical Department of Infectious Diseases and Hepatology without acute or chronic diarrhea and to assess the impact of antibiotic treatment on the development of enteritis in hospital. Other factors that may affect the risk of infection were also analyzed. RESULTS: Fourteen patients (14%) were carriers of [i]Clostridium difficile[/i] at admission. Second assessment taken after fourteen days of antibiotic treatment showed decrease in GDH antigen prevalence to eight subjects (12.1%). Three patients (3%) had diarrhea during hospitalization, and the toxins A and/or B were found in them. CONCLUSIONS: The frequency of [i]Clostridium difficile[/i] carriage among adults in Poland may be underestimated. Screening for Clostridium difficile GDH antigen may be useful although do not provide definite prognosis of symptomatic disease during ceftriaxone treatment. The risk of Clostridium difficile infection may be reduced mainly by rationalizing antibiotic therapy and following appropriate procedures.

Lymphocyte-To-Monocyte Ratio as the Best Simple Predictor of Bacterial Infection in Patients with Liver Cirrhosis.

Background and aim: The aim of this study was to assess the diagnostic performance of new morphology-related indices and Child-Turcotte-Pugh (CTP) and Model for End-Stage Liver Disease (MELD) scores during hospitalization in predicting the onset of bacterial infection in patients with liver cirrhosis. Material and methods: A total of 171 patients (56.9% males; median age 59 years; total number of hospitalizations 209) with liver cirrhosis were included in this observational study. The diagnosis of cirrhosis was made on the basis of clinical, biochemical, ultrasonic, histological, and endoscopic findings. The neutrophil-to-lymphocyte ratio (NLR), lymphocyte-to-monocyte ratio (LMR), modified aspartate aminotransferase-to-platelet ratio index (APRI), aspartate aminotransferase-to-alanine aminotransferase ratio (AAR), Fibrosis-4 index (FIB-4), platelet-to-lymphocyte ratio (PLR), neutrophil-to-monocyte ratio (NMR), and CTP and MELD scores were calculated for the cases of patients with cirrhosis. Results: Bacterial infection was diagnosed in 60 of the 209 (28.7%) hospitalizations of patients with cirrhosis. The most common infections were urinary tract infection (UTI), followed by pneumonia and sepsis. The more severe the liver failure, the greater the bacterial infection prevalence and mortality. Patients with decompensated liver cirrhosis were infected more often than subjects with compensated cirrhosis (50.0% vs. 12.9%, p = 0.003). The calculated MELD score, CTP, NLR, LMR, AAR, monocyte count, and C-reactive protein (CRP) concentration were also related to the bacterial infection prevalence, and mortality areas under the curve (AUC) were 0.629, 0.687, 0.606, 0.715, 0.610, 0.648, and 0.685, respectively. The combined model with two variables (LMR and CTP) had the best AUC of 0.757. The most common bacteria isolated from patients with UTI were Escherichia coli, Enterococcus faecalis, and Klebsiella pneumonia. Gram-negative bacteria were also responsible for spontaneous bacterial peritonitis (SBP), and together with gram-positive streptococci and staphylococci, these microorganisms were isolated from blood cultures of patients with sepsis. Significant differences were found between CTP classification, MELD score, NLR, LMR, AAR, CRP, and PLR in patients with cirrhosis with, or without, bacterial infection. Conclusions: Bacterial infection prevalence is relatively high in patients with liver cirrhosis. Although all analyzed scores, including the LMR, NLR, aspartate aminotransferase (AST)/alanine aminotransferase (ALT), CRP, CTP, and MELD, allowed the prediction of bacterial occurrence, the LMR had the highest clinical utility, according to the area under the curve (AUC) and odds ratio (OR).

Predictive power of Model for End-Stage Liver Disease and Child-Turcotte-Pugh score for mortality in cirrhotic patients.

AIM OF THE STUDY: To assess the performance of Child-Turcotte-Pugh (CTP) and Model for End-Stage Liver Disease (MELD) scores' kinetics during hospitalization in predicting in-hospital mortality in patients with liver cirrhosis. MATERIAL AND METHODS: One hundred and seventy-four cases of hospitalized liver cirrhosis patients were selected. The diagnosis of cirrhosis was made based on clinical, biochemical, ultrasonic, histological, and endoscopic findings and results. CTP and MELD scores at admission and ΔCTP and ΔMELD were calculated. Univariate and multivariate logistic regression and receiver-operating characteristic (ROC) curve analysis were performed. In the models, odds ratios (ORs) and 95% confidence intervals (CIs) were calculated. The area under the ROC curve (AUC) was used to measure the accuracy. For the optimal cutoff point, sensitivity (SE), specificity (SP), positive predictive value (PPV), and negative predictive value (NPV) were calculated. The Kaplan-Meier method was used to construct survival curves, and the log-rank test was used to compare time to death, with respect to MELD and CTP categories. RESULTS: Among the assessed scores, the highest area under the ROC curve (AUC) in univariate logistic regression analysis was calculated for ΔMELD ≥ 1, followed by ΔCTP ≥ 1, CTP > 8, and MELD > 17. Based on the selected criteria, multivariate models were created that were characterized by an outstanding ability to predict the in-hospital mortality. CONCLUSIONS: In-hospital mortality is relatively high in patients with liver cirrhosis. The combination of CTP and MELD scoring methods, combined with their kinetics, allows for the prediction of short-term mortality.

Bacterial infections and hepatic encephalopathy in liver cirrhosis-prophylaxis and treatment.

Infections are common among patients with liver cirrhosis. They occur more often in cirrhotic patient groups than in the general population and result in higher mortality. One reason for this phenomenon is bacterial translocation from the intestinal lumen that occurs as a consequence of intestinal bacterial overgrowth, increased permeability and decreased motility. The most common infections in cirrhotic patients are spontaneous bacterial peritonitis and urinary tract infections, followed by pneumonia, skin and soft tissue infections. Intestinal bacterial overgrowth is also responsible for hyperammonemia, which leads to hepatic encephalopathy. All of these complications make this group of patients at high risk for mortality. The role of antibiotics in liver cirrhosis is to treat and in some cases to prevent the development of infectious complications. Based on our current knowledge, antibiotic prophylaxis should be administered to patients with gastrointestinal hemorrhage, low ascitic fluid protein concentration combined with liver or renal failure, and spontaneous bacterial peritonitis as a secondary prophylaxis, as well as after hepatic encephalopathy episodes (also as a secondary prophylaxis). In some cases, the use of non-antibiotic prophylaxis can also be considered. Current knowledge of the treatment of infections allows the choice of a preferred antibiotic for empiric therapy depending on the infection location and whether the source of the disease is nosocomial or community-acquired.

Acute liver failure during treatment of interferon alpha 2a chronic hepatitis B and coinfection of parvovirus B19

Parvovirus B19 infection is associated with a broad spectrum of clinical manifestations among which some are well known but others remain controversial. The role of this infection as a cause of acute hepatitis or exacerbation of chronic liver disease requires discussion regarding its significance in a strategy of prevention and treatment of patients with chronic hepatitis. Clinical importance of this infection in patients with chronic hepatitis B treated with pegylated interferon alpha 2a is still unclear but exactly in this population significant complications during treatment may arise. Parvovirus B19 infection is not rare among persons with chronic hepatitis B, therefore searching for co-infection should be placed in standard diagnostic procedures especially in case of exacerbation of chronic hepatitis, pancytopaenia or anaemia of unknown origin. Pegylated interferon alpha 2a still remains a gold standard of therapy of patients with chronic hepatitis B according to European (EASL) and Polish guidelines. We present a case of 35 years old woman treated with pegylated interferon alpha 2a who developed acute liver failure in 23rd week of chronic hepatitis B therapy. An exacerbation of hepatitis with encephalopathy and pancytopaenia have been observed. Parvovirus B19 and HBV co-infection does not increase the frequency of liver function abnormalities in patients with chronic hepatitis B. Further investigations should be done to describe the natural course of co-infection with parvovirus B19 and HBV and to establish possible association between parvovirus B19 infection and chronic hepatitis B and also the influence of interferon alpha 2a on the infections course.

Cerebrospinal fluid ferritin concentration in patients with purulent, bacterial meningitis ­ own observations / Stezenie ferrytyny w plynie mózgowo-rdzeniowym chorych z ropnymi, bakteryjnymi zapaleniami opon i mózgu - obserwacje wlasne

THE AIM: The aim of the study was to evaluate the usefulness of cerebrospinal fluid (CSF) ferritin concentration assessment in adults with purulent, bacterial meningoencephalitis. MATERIAL AND METHODS: The investigation was performed in 18 subjects hospitalized at the Clinical Ward of Infectious Diseases, Medical University of Silesia in Bytom from 2008 through 2012, for purulent, bacterial meningoencephalitis. The patients were divided into two groups, according to severity of their clinical condition: Group I ­ very severe course of the disease, group II ­ moderate and mild course of the disease. In all the individuals, CSF interleukin-6 concentration was evaluated during the first 24 hours of hospitalization. RESULTS: Mean CSF ferritin concentration in patients in very severe clinical condition (group I) was 314.71 ng/mL as compared to 162.13 ng/mL in subjects of group II with moderate and mild course of the disease. The difference between CSF mean concentration of this cytokine was statistically significant (p<0.01). Correlations between CSF ferritin and CSF protein and lactate were determined. The control assays performed in 6 patients from group I revealed only slightly decrease of CSF ferritin level in the fatal course of the disease. In survivals with recovery CSF concentration of this protein was decreased markedly as compared to the initial level. CONCLUSIONS: The obtained results indicate the usefulness of CSF ferritin concentration assessment in estimation of intensity of inflammation in the subarachnoid space, and indirectly, of severity of the patient's clinical condition. The level of this protein concentration also seems to be helpful as a prognostic marker in purulent, bacterial meningoencephalitis.

Efficacy of HCV treatment in Poland at the turn of the interferon era - the EpiTer study.

THE AIM OF THE STUDY: Was to analyze the efficacy achieved with regimens available for chronic hepatitis C (CHC) in Poland between 2013 and 2016. MATERIAL AND METHODS: Data were collected from 29 centers and included 6786 patients with available sustained virologic response (SVR) data between 1 January 2013 and 31 March 2016. RESULTS: The sustained virologic response rate for genotypes (G) 1a, 1b, 2, 3 and 4 was 62%, 56%, 92%, 67% and 56% respectively; 71% patients (n = 4832) were treated with pegylated interferon α (Peg-IFNα) and ribavirin (RBV), with SVR rates of 58%, 49%, 92%, 67% and 55% respectively. The sustained virologic response among 5646 G1 infected patients was the lowest with natural interferon α (7%, n = 70) or PegIFN (50%, n = 3779) with RBV, and improved in those receiving triple regimens of Peg-IFN + RBV combined with boceprevir (47%, n = 485), telaprevir (64%, n = 805), simeprevir (73%, n = 132) or sofosbuvir (70%, n = 23). The sustained virologic response with interferon-free regimens of sofosbuvir and RBV (n = 7), sofosbuvir and simeprevir (n = 53), and ledipasvir and sofosbuvir (n = 64) achieved 86%, 89% and 94% respectively. The highest SVR of 98% was observed with ombitasvir/paritaprevir combined with dasabuvir (n = 227). Patients infected with G3 (n = 896) and G4 (n = 220) received mostly Peg-IFN + RBV with SVR of 67% and 56% respectively. Interferon-free regimens were administered in 18 G3/G4 patients and all achieved an SVR. Sofosbuvir combined with Peg-IFN and RBV was administered to 33 patients with an SVR rate of 94%, and a similar rate was achieved among 13 G2 patients treated with interferon and RBV. CONCLUSIONS: We observed significant differences in efficacy of HCV regimens available in Poland at the turn of the interferon era. The data will be useful as a comparison for therapeutic options expected in the next few years.

Prevalence of HCV genotypes in Poland - the EpiTer study.

THE AIM OF THE STUDY: Was to assess current prevalence of hepatitis C virus (HCV) genotypes in Poland, including their geographic distribution and changes in a given period of time. MATERIAL AND METHODS: Data were collected with questionnaires from 29 Polish centers and included data of patients diagnosed with HCV infection between 1 January 2013 and 31 March 2016. RESULTS: In total, data of 9800 patients were reported. The highest prevalence was estimated for genotype 1b (81.7%), followed by 3 (11.3%), 4 (3.5%), 1a (3.2%) and 2 (0.2%). Genotype 5 or 6 was reported in 6 patients only (0.1%). The highest prevalence of genotype 1 was observed in central (lódzkie, mazowieckie, swietokrzyskie), eastern (lubelskie) and southern (malopolskie, slaskie) Poland. The highest rate for genotype 3 was observed in south-western (dolnoslaskie, lubuskie) and eastern (podlaskie, warminsko-mazurskie and podkarpackie) Poland. Compared to historical data, we observed an increasing tendency of G1 prevalence from 72.0% in 2003 to 87.5% in 2016, which was accompanied by a decrease of G3 (17.9% vs. 9.1%) and G4 (9.0% vs. 3.1%). CONCLUSIONS: Almost 85% of patients with HCV in Poland are infected with genotype 1 (almost exclusively subgenotype 1b), and its prevalence shows an increasing tendency, accompanied by a decrease of genotypes 3 and 4.

Chemokine CXCL13 concentration in cerebrospinal fluid in patients with neuroborreliosis--own observations.

THE AIM: of the study was to evaluate the usefulness of cerebrospinal fluid chemokine CXCL13 concentration assay in diagnostics of neuroborreliosis in adults. MATERIAL AND METHODS: Investigations were carried out in 22 patients treated for neuroborreliosis , manifested as lymphocytic meningitis, at the Department of Infectious Diseases, Medical University of Silesia, in Bytom between 2011-2013. Based on the presence or absence of anti-borrelial antibodies in the cerebrospinal fluid, the examined individuals were divided into two groups on the day of admission: group I--patients with antiborrelial antibodies in the cerebrospinal fluid (confirmed diagnosis of neuroborreliosis), group II--patients without antiborrelial antibodies in the cerebrospinal fluid (possible diagnosis of neuroborreliosis). In all patients the cerebrospinal fluid CXCL13 level was assessed on the first day of hospitalization. Control tests were performed in both groups after 14 days of therapy with antibiotics. RESULTS: Mean cerebrospinal fluid CXCL13 concentration in group I on the 1st day was 4123 pg/mL, and in group II--3422 pg/mL. Differences in mean concentrations of this chemokine were statistically insignificant. No correlations between examined mean CXCL13 concentrations and other cerebrospinal fluid inflammatory parameters were revealed. The control tests showed the evident decrease of CXCL13 level in cerebrospinal fluid in both groups. Besides, in individuals of group II anti-Borrelia burgdorferi antibodies appeared in cerebrospinal fluid, whereas in group I, the control results of this parameter were similar to preliminary values. CONCLUSION: The obtained results indicate a kind of usefulness of estimation of cerebrospinal fluid chemokine CXCL13 concentration in diagnostics of early, acute neuroborreliosis, manifested as lymphocytic meningitis, especially in case of anti-borrelia antibodies absence in cerebrospinal fluid. Changes in this chemokine concentrations, opposite to cerebrospinal fluid levels of anti-borrelia antibodies, may be prognostic in acute, early neuroborreliosis.

The epidemiological and clinical analysis of Clostridium difficile infections in patients hospitalized due to the infection at the Department of Infectious Diseases in Bytom.

UNLABELLED: Clostridium difficile infections are becoming a more serious problem as hospital-acquired infections and the consequence of common antibiotic therapy, also on an out-patient basis. AIM OF THE STUDY: The aim of the study was the epidemiological and clinical analysis of patients with Clostridium difficile-associated disease (CDAD) at the Clinical Department of Infectious Diseases and Hepatology, Bytom in 2014. MATERIAL AND METHODS: A retrospective analysis of the medical documentation of patients with the diagnosis of CDAD was performed. The study group was comprised of 24 patients. The following factors were analysed: gender, age, recent hospitalization, use of proton-pump inhibitors, H2-receptor inhibitors, use of antibiotics, co-morbidities, and the clinical course with consideration given to additional laboratory tests (CRP, creatinine, WBC count). RESULTS: All patients with diagnosed CDAD had been previously hospitalized and 75% of subjects were treated with antibiotics in the period preceding the onset of the disease. Recurrence of the disease was observed in 29% of cases, on average, 12.5 days after hospital discharge. In 16.7% of patients, CDAD resulted in death. Higher CRP concentrations on admission were observed in patients who died compared to the survivors (91.1 mg/l vs. 33.6 mg/l, p=0.015). Additionally, higher concentrations of CRP and leukocytosis were observed in patients with an unfavourable outcome of the disease. Respiratory insufficiency and hypotension were connected with a higher risk of death. CONCLUSION: Hospitalization, antibiotic therapy, advanced age and co-morbidities may contribute to the occurrence of CDAD. In our study, initially high concentrations of CRP, respiratory insufficiency and hypotension were the predictive factors of a fatal outcome of the disease. The dynamics of changes in the leukocyte value and CRP concentration were of lesser importance.

Increased concentration of interferon lambda-3, interferon beta and interleukin-10 in the cerebrospinal fluid of patients with tick-borne encephalitis.

Tick-borne encephalitis (TBE) has a wide clinical spectrum, from asymptomatic to severe encephalitis, and host-dependent factors determining the outcome remain elusive. We have measured concentrations of pro-inflammatory/Th1 interferon-γ (IFNγ), immunomodulatory/Th2 interleukin-10 (IL-10), anti-viral type I (IFNß) and type III (IFNλ3) interferons in cerebrospinal fluid (csf) and serum of 18 TBE patients, simultaneously genotyped for polymorphisms associated with the expression of genes IFNL3 (coding IFNλ3), IL10, CD209 and CCR5. IL-10, IFNß and IFNλ3 were up-regulated in csf, with IFNλ3 level higher in patients with the milder clinical presentation (meningitis) than in meningoencephalitis. There was an increased serum IFNß and a tendency for increased serum IL-10 in meningitis patients. Genotype in rs12979860 locus upstream of IFNL3 was associated with IFNλ3 expression and in rs287886 (CD209) - IL-10 expression. IL-10, IFNß and IFNλ3 are expressed and play a protective role in TBE and their expression in TBE patients is associated with genetic polymorphisms.

Cerebrospinal fluid interleukin-6 concentration in patients with purulent, bacterial meningitis - own observations.

AIM: This study aimed at evaluating the usefulness of determining cerebrospinal fluid (CSF) interleukin-6 (IL-6) concentration in adults with purulent, bacterial meningoencephalitis. MATERIALAND METHODS: A study group consisted of 16 patients hospitalized in the Department of Infectious Diseases of the Medical University of Silesia in Bytom in 2008 - 2012 due to purulent, bacterial meningoencephalitis. All of them were classified into two groups based on clinical severity, assessed on admission: group I - severe condition, group II - moderately severe or mild condition. CSF IL-6 concentration was measured in all patients on the first day of hospitalization. RESULTS: Mean concentrations of IL-6 in CSF were assessed at 391.54 pg/mL and 110.51 pg/mL in patients in severe (group I) and moderately severe or mild condition (group II), respectively. Differences between CSF mean concentrations of this cytokine in both groups were statistically significant (p<0.01). No correlations between CSF IL-6 concentrations and other CSF inflammatory parameters were determined. Control testing performed in 5 patients of group I revealed only slight decrease of CSF IL-6 concentration in fatal cases. In case of patients who recovered from disease, IL-6 concentration in CSF was evidently decreased compared to its initial value. CONCLUSIONS: Results suggest the usefulness of determining CSF interleukin-6 concentration to estimate inflammation intensity in the subarachnoid space, and indirectly, patient's clinical severity. IL-6 concentration may be also of prognostic importance in purulent, bacterial meningoencephalitis.

Distribution of HCV genotypes in Poland.

UNLABELLED: Available data on prevalence of HCV genotypes in Poland are insufficient. The aim of the study was the analysis of distribution of HCV genotypes in Poland over the period of recent 10 years regarding the age of patients and the regions of the country. MATERIAL AND METHODS: Analysis of HCV genotypes in Poland was carried out between 2003 and 2012, and included 14 651 patients from 22 centers where patients with chronic viral hepatitis C are diagnosed and treated. Genotypes were analyzed in age groups (< 20 years of age, 20-40 years of age, > 40 years of age) as well as in populations of HBV and HIV co-infections. RESULTS: Genotype (G) 1 infection was demonstrated in 79.4%, G2 -0.1%, G3- 13.8%, G4- 4.9%, G6-0.09% and mixed infections in 1.6%. There was no infection with genotype 5. The highest prevalence of G1 was observed in the Lódzkie voivodship (89.2%) and the Slaskie voivodship (86.7%) while the lowest one in the Warminsko-mazurskie (62.0%) and the Podlaskie voivodships (68.2%). Genotype 3 most commonly occurs in the Warminsko-mazurskie (28.1%), and the Podlaskie voivodships (23.0%) and is least common in the Malopolskie (7.9%) and the Lódzkie voivodships (9.0%). Genotype 4 is more common in the Kujawsko-pomorskie (11.7%) and the Podlaskie voivodships (8.6%) and relatively less common in the Lubelskie (1.1%) and the Lódzkie voivodships (1.8%). Prevalence of G1 infection in 2003-2004 was 72% and increased up to 85.6% in 2011-2012, that was accompanied by decrease of G3 prevalence from 17% to 8% in this period. In HBV co-infected (n = 83), G1 infection was demonstrated in 85.5%, G3 - in 7.2%, G4 -4.8%, and mixed genotypes in 6%. Among HIV co-infected (n = 391), a much lower prevalence of G1 (33.0%) and a high of G3 (40.4%) as well as G4 (24.0%) were observed. CONCLUSIONS: There is a geographic variability of HCV genotypes prevalence in Poland. Increase of HCV G1 infections and decrease of G3 and G4 were observed in the last 10 years. Genotypes G3 and G4 occur more often in HCV/HIV co-infected than in HCV mono-infected patients.

HIV-1 integrase resistance among antiretroviral treatment naive and experienced patients from Northwestern Poland.

BACKGROUND: HIV integrase inhibitor use is limited by low genetic barrier to resistance and possible cross-resistance among representatives of this class of antiretrovirals. The aim of this study was to analyse integrase sequence variability among antiretroviral treatment naive and experienced patients with no prior integrase inhibitor (InI) exposure and investigate development of the InI drug resistance mutations following the virologic failure of the raltegravir containing regimen. METHODS: Sequencing of HIV-1 integrase region from plasma samples of 80 integrase treatment naive patients and serial samples from 12 patients with observed virologic failure on raltegravir containing treatment whenever plasma vireamia exceeded >50 copies/ml was performed. Drug resistance mutations were called with Stanford DB database and grouped into major and minor variants. For subtyping bootstrapped phylogenetic analysis was used; Bayesian Monte Carlo Marcov Chain (MCMC) model was implemented to infer on the phylogenetic relationships between the serial sequences from patients failing on raltegravir. RESULTS: Majority of the integrase region sequences were classified as subtype B; the remaining ones being subtype D, C, G, as well as CRF01_AE , CRF02_AG and CRF13_cpx recombinants. No major integrase drug resistance mutations have been observed in InI-treatment naive patients. In 30 (38.5%) cases polymorphic variation with predominance of the E157Q mutation was observed. This mutation was more common among subtype B (26 cases, 54.2%) than non-B sequences (5 cases, 16.7%), p=0.00099, OR: 5.91 (95% CI:1.77-22.63)]. Other variants included L68V, L74IL, T97A, E138D, V151I, R263K. Among 12 (26.1%) raltegravir treated patients treatment failure was observed; major InI drug resistance mutations (G140S, Q148H and N155H, V151I, E92EQ, V151I, G163R) were noted in four of these cases (8.3% of the total InI-treated patients). Time to the development of drug resistance ranged from 2.6 to 16.3 months with mean increase of HIV viral load of 4.34 (95% CI:1.86-6.84) log HIV-RNA copies/ml at the time of emergence of the major mutations. Baseline polymorphisms, including E157Q were not associated with the virologic failure on raltegravir. CONCLUSIONS: In InI treatment naive patients polymorphic integrase sequence variation was common, with no major resistance mutants. In the treatment failing patients selection of drug resistance occurred rapidly and followed the typical drug resistance pathways. Preexisting integrase polymorphisms were not associated with the treatment failure.