Secondary bacterial infections of the respiratory tract in COVID-19 patients.

INTRODUCTION: Secondary Bacterial Infections (SBIs) of the respiratory system are one of the biggest medical concerns in patients undergoing hospitalization with a diagnosis of COVID-19. This study aims to provide relevant data for the initiation of appropriate empirical treatment after examining the etiology and antimicrobial resistance of SBIs in COVID-19 patients under care in the Intensive Care Units (ICUs) in the largest pandemic hospital of our country. METHODOLOGY: Between March 16, 2020 and December 31, 2021, 56,993 COVID patients were hospitalized, of which 7684 were admitted to ICUs. A total of 1513 patients diagnosed with SBIs have been included in this study. During the course of the study, demographic data, clinical course, etiology and antimicrobial resistance data of all patients were collected. RESULTS: The most common causative agents of SBIs were inferred as Acinetobacter baumanii (35.1%), Staphylococcus aureus (15.2%), Klebsiella pneumoniae (12.3%) and Pseudomonas aeruginosa (10.4%). The isolation rates of carbapenem-resistant and colistin-resistant A. baumannii, K. pneumoniae and P. aeruginosa were 83.7%; 42.7%, 79.2%, and 5.6%, 42.7%, 1.7%, respectively. Acinetobacter pittii clustering was seen in one of the ICUs in the hospital. Multidrug resistant 92 (5.4%) Corynebacterium striatum isolates were also found as a causative agent with increasing frequency during the study period. CONCLUSIONS: SBI of the respiratory system is one of the major complications in patients hospitalized with COVID-19. The antimicrobial resistance rates of the isolated bacteria are generally high, which indicates that more accurate use of antibacterial agents is necessary for SBIs in patients hospitalized with COVID-19 diagnosis.

[Evaluation of blood culture practices: Use of system (Epicenter) data]. / Kan kültürü uygulamalarinin degerlendirilmesi: Isletim sistemi (Epicenter) verilerinin kullanimi.

Sepsis is a serious clinical problem and estimated to be responsible for 18 million annual deaths worldwide. Therefore, the use and the rapid processing of blood cultures are important for the transition from empiric therapy to directed therapy. The aim of this study was to assess the best blood culture practices in Turkey. We have examined the collection practices and techniques at four different hospitals, and a total of 165.443 blood culture bottles were evaluated (2013-2015). At the preanalytical phase most of the data which were important and which could support hospital quality systems/practices were not entered into the HIS and EpiCenter system. At the analytical phase loading of the bottles and removal of positive bottles primarily occurred between 6:00 and 9:00 AM but the positivity rate of the bottles showed a homogeneous distribution throughout the day. In other words, there were significant delays at processing positive blood culture bottles related to laboratory workers. The effect of education regarding best practices, transition from single bottle to two bottle cultures was successful in all hospitals. Single bottle usage decreased below 10% in all hospitals. Significantly more positive cultures were detected at multiple cultures when compared with the single bottle collection practice. In retrospective patient records, it was seen that all the laboratories reported the results of Gram staining to the clinics. However, these data were not recorded to the EpiCenter. The contamination rates of Ankara Numune Hospital and Akdeniz University Faculty of Medicine Hospital are 6.2% and 5.4% respectively, contamination rates were not reported in other hospitals. The most common isolates detected in blood cultures were Escherichia coli, Klebsiella pneumoniae, Enterococcus faecium, Staphylococcus aureus, and Acinetobacter baumannii. The mean time for the detection of these organisms were less than 20 hours in the aerobic bottle and anaerobic bottles. A total of 79.6% of facultative anaerobic isolates were detected in both bottles; 9.8% were detected only in the aerobic bottles; 10.6% of the isolates were detected only in the anaerobic bottles. As a result, the educational efforts in Turkey have met with success for transition from collecting single bottle blood culture sets to two bottle blood cultures. However, further efforts are needed to increase the number of blood culture sets collected during a 24 hours' period. In addition, errors at the preanalytical, analytical and postanalytical periods (taking samples, loading bottles into the system and processing positive blood cultures) should be eliminated.

[Investigation of oxacillinase genes in nosocomial multidrug-resistant Acinetobacter baumannii isolates by multiplex PCR and evaluation of their clonal relationship with Rep-PCR]. / Nozokomiyal çok ilaca dirençli Acinetobacter baumannii izolatlarinda oksasilinaz genlerinin multipleks PCR ile arastirilmasi ve klonal iliskilerinin Rep-PCR ile degerlendirilmesi.

Acinetobacter baumannii is a major nosocomial pathogen which can cause infections with high morbidity and mortality in hospitalized patients. In recent years A.baumannii has become a serious clinical problem because of the development of resistance to many antibiotics, and especially to carbapenems. The aims of this study were to investigate the oxacillinase genes responsible for carbapenem resistance in multidrug resistant (MDR) A.baumannii strains and to evaluate the clonal relationship between these strains. A total of 62 MDR A.baumannii strains isolated from various clinical specimens (24 tracheal aspirate, 14 wound, 10 blood, 7 urine, 2 abscess, 2 sputum, 2 catheter tip, 1 pleural fluid) of hospitalized patients in intensive care units (n= 42) and other inpatient clinics (n= 20) between February-March 2012, were included in the study. Identification and antibiotic susceptibility of A.baumannii isolates were performed by Vitek-2 automated system (bioMérieux, France), and the identified bacteria were confirmed by Maldi Biotyper (Bruker Daltonics, Germany) system. Imipenem, meropenem, colistin and tigecycline were additionally tested by E-test strips (bioMérieux, France). The presence of carbapenemase-producing OXA genes (blaOXA-23-like, blaOXA-40-like, blaOXA-51-like and blaOXA-58-like) were detected by multiplex PCR (hyplex® CarbOxaID test system, Amplex Diagnostics, Germany) and the clonal relationship between isolates were investigated by rep-PCR method (DiversiLab, bioMérieux, France). In our study, all isolates were found resistant to ampicillin-sulbactam, piperacillin, piperacillin-tazobactam, ceftazidime, cefepime, imipenem, meropenem, ciprofloxacin, levofloxacin and tetracycline, while the resistance rates for amikacin, gentamicin, trimethoprim-sulfamethoxazole, netilmicin and tigecycline were 88.7%, 88.7%, 82.3%, 43.5% and 27.4%, respectively. All A.baumannii isolates were susceptible to colistin. All of the strains were positive for blaOXA-23-like and blaOXA-51-like genes, while blaOXA-40-like and blaOXA-58-like genes were not detected in any of them. Simultaneous cultures from environmental samples collected from inpatient clinics in which MDR A.baumannii strains isolated were negative in terms of A.baumannii growth. In evaluation of clonal relationship between isolates, 48 strains (77.4%) showed greater than 95% similarity and formed a big cluster, named Cluster A. The remaining 14 isolates formed 3 small clusters (each had 2 isolates), named Cluster B, C and D, showing greater than 95% similarity. Majority of isolates (58.3%) in Cluster A were from patients in the surgical intensive care unit, and the first isolate from this cluster was also from a patient in the same unit. In our opinion, isolates from Cluster A may have spread to other clinics from surgical intensive care unit through transferred patients or medical and non-medical devices and equipment. Nosocomial MDR A.baumannii isolates in our hospital are highly resistant to antibiotics and all harboured blaOXA-23-like genes. The rep-PCR analysis of these isolates indicated that a large portion of A.baumannii strains were clonally closely related, and they probably from the same source and common ancestor, and separated shortly from each other. This data emphasizes that the choices of treatment are quite limited for inpatients, and the need for improvement of the infection control measures in our hospital.

[The rare genes related to resistance to macrolide-lincosamide and streptogramin B group antibiotics among coagulase-negative staphylococci]. / Koagülaz-Negatif Stafilokoklarda Makrolid-Linkozamid-Streptogramin B Grubu Antibiyotiklere Karsi Nadir Direnç Genlerinin Arastirilmasi

Macrolide-lincosamide-streptogramin B (MLSB) group antibiotics are recommended as first choice in the treatment of staphylococcal infections. All of those drugs bind to the 50S subunit of bacterial ribosomes, thus cross-resistance is a major concern in this group of drugs. The mechanisms associated to resistance are (a) ribosomal methylation due to the methylases encoded by erm genes, (b) active drug efflux due to msrA, msrB, vga, vgb gene activity, (c) enzymatic inactivation of the drug due to the activity of linA, vat, vatB genes. While the most common resistance genes are ermA, ermB, ermC, msrA and msrB genes; linA, vga, vgb, vat and vatB genes have also been found in some studies. In this study it was aimed to investigate the presence of the rare MLSB resistance genes and their coexistence with erm and msr genes in 454 clinical isolates of coagulase-negative staphylococci (CNS). Of them 46.5% (n= 211) were S.hominis, 30.8% (n= 140) were S.epidermidis, 12.1% (n= 55) were S.haemolyticus, 3.5% (n= 16) were S.warnerii and 7% (n= 32) were the other coagulase-negative staphylococcal species. Resistance phenotypes were determined by using D-test method according to the recommendation of Clinical and Laboratory Standards Institute (CLSI). With the D-test 107 (23.6%) strains were determined as M phenotype (resistant to erythromycin and inducible clindamycin resistance was not detected), 92 (20.3%) were iMLSB phenotype (inducible clindamycin resistance was detected by the D-test) and 110 (24.2%) were cMLSB phenotype (constitutive erythromycin and clindamycin resistance was detected). linA, vga, vgb, vat, vatB, ermA, ermB, ermC, msrA, msrB genes were investigated by polymerase chain reaction in all strains showing iMLSB (n= 92) and cMLSB (n= 110) phenotypes and 46 randomly selected strains among 107 strains exhibiting the M phenotype. linA gene was found in 91 (20%) strains as single gene or in combination with erm or msr genes, and vga gene was found in 19 (4.2%) strains. linA gene was found in 52% of iMLSB phenotype, in 26% of cMLSB phenotype and 13% of M phenotype while vga gene was found in 5.4% of iMLSB phenotype, in 12% of cMLSB phenotype and in 0.9% of M phenotype. The most common resistance gene among iMLSB and cMLSB phenotypes was ermC (32.6% and 42.7%, respectively), followed by ermC + linA gene combination (31.5% and 14.5%, respectively). The most frequent gene combination was msrA and msrB in M phenotype (34.8%) and it was followed by a combination of msrA + msrB + linA genes (19.1%). None of the strains revealed presence of vgb, vat and vatB genes. There were no previous reports about the rarely detected resistance genes against MLSB antibiotics in our country. This was the first study which reported the frequency of linA, vga, vgb, vat and vatB genes in MLSB resistant CNS. In conclusion, since linA and vga genes were detected in high frequency in MLSB resistant CNS in this study, it was thought that the investigation of these genes should be included in the further related epidemiologic gene research.

[Phenotypic and genotypic traits of vancomycin-resistant enterococci in a public hospital: the first vanB-positive Enterococcus faecium isolates]. / Bir Devlet Hastanesinde Vankomisine Dirençli Enterokok Suslarinin Fenotipik ve Genotipik Olarak Degerlendirilmesi: Ilk vanB-Pozitif Enterococcus faecium Izolatlari

Thirty eight vancomycin resistant enterococci (VRE) were isolated in one year surveillance study for hospital infection control programme in a state hospital in Ankara, Turkey. All isolates were identified as Enterococcus faecium by VITEK2 system (bioMerieux, France). Vancomycin and teicoplanin resistant 30 strains were defined as vanA phenotype while vancomycin-resistant teicoplanin-susceptible eight strains were defined as vanB phenotype. vanA genes were found in 30 strains while vanB genes were found in five strains by using PCR method. Those five strains were the first vanB positive E.faecium strains in our country. VRE strains revealed six different band patterns by PFGE, while six isolates could not be classified. All isolates with vanB type resistance were found in the same cluster. Source of vanB positive strains was considered as the hemodialysis unit. When the previous national reports related to vancomycin-resistant enterococci were considered, this was the first report of vanB positive E.faecium isolates in our country. This emphasized that both the diversity of VRE and the isolation rate was increasing. In order to eliminate the spread of VRE, effective surveillance studies should be performed and protective measures should be established promptly.