When the problem with carbapenem-resistant Enterobacteriaceae (CRE) increases, the older antimicrobial agents such as colistin and fosfomycin are used for the treatment of these infections. In this study, the broth microdilution method for colistin and the agar dilution method for fosfomycin were used for a total of 147 multidrug-resistant (MDR) or extensively drug-resistant (XDR) strains of CRE. The study included Klebsiella pneumoniae (91.16%), Escherichia coli (7.48%), Enterobacter cloacae (0.68%), and Serratia marcescens (0.68%). All these strains produce various types of carbapenemase, including OXA-48, NDM, and KPC. Some of these strains also have three different carbapenemase mechanisms, including OXA-48 (78.23%), NDM (2.04%), and KPC (0.68%) or OXA-48 and NDM (10.88%), or OXA-48 and KPC (0.68%). About 76.19% of the strains and 67.35% of the strains were resistant for colistin and fosfomycin, respectively. A total of 21 out of 35 colistin-susceptible strains were found to be susceptible to fosfomycin. This study showed that the resistance rates of colistin and fosfomycin are high. The MDR and XDR strains of CRE are spreading in our region and thus a monitoring system for CRE should be followed. Moreover, the applicability of antimicrobial stewardship programs should be increased in all inpatient and outpatient settings.

In this study, the presence of genes responsible for the pathogenicity and antibiotic resistance profile of enterococci isolated from various foodstuffs of animal origin was investigated. The percentage prevalence of enterococci was 54.1% (203/375) and the average count was found to be 3.81 log cfu/ml-g. Species-specific primers revealed Enterococcus faecalis as the predominant species carrying one or more virulence-associated traits of efa, gelE, ace, esp and agg genetic markers. Only one E. faecium isolate (from milk) was positive for the esp gene. Regarding antibiotic resistance, the highest frequency of resistance was observed for tetracycline (21.7%), followed by quinupristin/dalfopristin (13.3%), ciprofloxacin (2.0%), penicillin (2.0%), linezolid (1.0%), ampicillin (1.0%), streptomycin (1.0%), and gentamicin (0.5%). Enterococcus faecalis showed a higher prevalence of antibiotic resistance than other enterococci. The percentage of multidrug resistance among the isolates was 3.4%. Twenty-nine E. faecalis isolates (26.6%) carrying one of the virulence-associated traits were at the same time resistant to at least one antibiotic. Our results show that foods of animal origin, including ready-to-eat products, may be reservoirs of antibiotic-resistant and potentially virulent enterococci.

Haemophilus bacteria are normally present in the upper respiratory tract of healthy individuals. However, these bacteria could be opportunistic pathogens especially in children. The present study was conducted to determine beta-lactamase activity of Haemophilus from the throat cultures of children with upper respiratory tract infections. 154 Haemophilus strains were isolated from throat swabs of 208 children whom had upper respiratory tract infections. Among the 154 Haemophilus strains isolated, 117 H. influenzae (76%), 35 H. parainfluenzae (22.7%), and two H. aphrophilus (13%) were identified by API NH. beta-Lactamase activity was positive in 42 isolates of 117 H. influenzae isolates, while it was negative in 75 isolates. beta-Lactamase activity was positive in 20 H. parainfluenzae isolates, and negative in 15. All the H. aphrophilus isolates were beta-lactamase negative. It is known that beta-lactamase positive Haemophilus bacteria are resistant to some antibiotics. Therefore, the antibiotic resistance of Haemophilus was further investigated in relation to beta-lactamase activity. The in vitro antibacterial susceptibilities of Haemophilus strains for ampicillin, sulbactam-ampicillin, trimethoprim-sulfamethoxazole, gentamicin, chloramphenicol and ciprofloxacin were tested by disk diffusion method on chocolate agar. In 42 beta-lactamase-positive H. influenzae isolates, 32 isolates were resistant against ampicillin. In 20 beta-lactamase-positive H. parainfluenzae isolates, 16 were resistant against ampicillin. The two beta-lactamase negative H. aphrophilus were sensitive to ampicillin. Biotypes and serotypes were also investigated. Biotypes of H. influenzae strains were as follows: 40 strains biotype II, 25 strains biotype I, 14 strains biotype III, and 38 strains biotypes VII, VIII, V, and IV. Biotypes of 35 H. parainfluenzae strains were: 6 strains biotype III, 5 strains biotype I, 5 strains biotype IV. Biotypes of remaining 19 isolates were II, VIII, VI and VII. The serotypes of H. influenzae strains were determined by specific antiserums. Serotypes of 117 H. influenzae found were type a, b, c, d, and f.

Antibiotic resistance is one of the most important public health problem and one of the most critical steps in preventing resistance is the monitorization of the resistance. Local, regional and global monitoring enables the spread of antibiotic resistance to be understood more clearly. In this study, it was aimed to evaluate the results of the pilot study for the establishment of molecular-based carbapenem surveillance system in Escherichia coli and Klebsiella pneumoniae isolates and to investigate the carbapenemase epidemiology in Turkey. Hospitals (n= 28) from 26 different statistical level II regions from Turkey were included in the study. The hospitals participated in the study submitted ten carbapenem susceptible and ten carbapenem resistant E.coli and K.pneumoniae isolates to our laboratory that were isolated in two different periiods of six-month either between 1 March-31 August or 1 April-30 September 2019. A total of 509 isolates were collected from 26 of the 28 participating hospitals in the study. Isolates were identified by matrix assisted laser desorptionization-time of flight mass spectrophotometry (MALDI TOF MS) (Bruker Daltonics, Germany) method and antibiotic susceptibility tests for imipenem, meropenem and colistin were studied by broth microdilution. Moreover, susceptibilities to amikacin, amoxicillin-clavulanic acid, ampicillin, aztreonam, cefepime, cefotaxime, ceftazidime, ciprofloxacin, ertapenem, gentamicin, piperacillin-tazobactam, tobramycin and trimethoprim-sulfamethoxazole were determined by disc diffusion method. The resistance genes were investigated in isolates which were found to be phenotypically resistant to carbapenem and colistin, in house method was used to investigate carbapenemase genes and a commercial colistin resistant real-time PCR kit (Biospeedy, Turkey) was used for colistin resistance genes. In total, 493 of the 509 isolates collected from hospitals were identified as E.coli (25.7%, n= 127) and K.pneumoniae (74.3%, n= 366) and included in the study. It was determined that 31% of the isolates evaluated were from community-acquired infections and 69% were either from healthcare-associated infections or from colonization sites. Among the tested isolates, 248 (50.3%) were susceptible to carbapenems and 245 (49.7%) were resistant. The types of carbapenemases in carbapenemase-producing isolates were OXA-48 (52.2%), KPC (16.1%), NDM-1 (15%), OXA-48 + NDM-1 (12.6%), KPC + NDM-1 (2.8%) and VIM (0.5%) and OXA-48+VIM (0.5%). Resistance to colistin was detected in 23.3% of the isolates but mcr1-8 genes were not detected. It was found that all colistin resistant isolates are resistant to at least one of the carbapenems. The importance of a molecular-based antimicrobial resistance surveillance system in our country was demonstrated with this pilot study. It is thought that continuous monitoring of these epidemiological features will contribute to the management of infections due to carbapenemase-producing organisms.

The synergistic activity of eravacycline in combination with colistin on carbapenem-resistant A.baumannii (CRAB) isolates was evaluated in this study. Minimum inhibitory concentrations (MICs) of eravacycline and colistin were determined by the broth microdilution method. MICs values ranged between 1 to 4 mg and 0,5 to 128 mg/L for eravacycline and colistin, respectively. In-vitro synergy between eravacycline and colistin was evaluated by using the chequerboard methodology. Synergistic activity was found in 10 % of the strains, and additive effect in 20 %. No antagonism was detected. Similar activity was also observed in colistin resistant CRAB isolates. The result of this study indicates that eravacycline and colistin combination may be a potential therapeutic option for the treatment of CRAB related infections..