Dissemination of High-Risk Clones Enterobacterales among Bulgarian Fecal Carriage Isolates.

The gastrointestinal tract is an important reservoir of high-risk Enterobacteria clones and a driver of antimicrobial resistance in hospitals. In this study, patients from six hospitals in four major Bulgarian towns were included in this study. Overall, 205 cefotaxime-resistant isolates (35.3%) of Enterobacterales order were detected in fecal samples among 580 patients during the period of 2017-2019. ESBL/carbapenemase/plasmidic AmpC producer rates were 28.8%, 2.4%, and 1.2%, respectively. A wide variety of ESBLs: CTX-M-15 (41%), CTX-M-3 (24%), CTX-M-27 (11%), and CTX-M-14 (4%) was found. The carbapenemases identified in this study were New Delhi metalo-ß-lactamase (NDM)-1 (5.4%) and Klebsiella carbapenemase (KPC)-2 (1.5%). Most NDM-1 isolates also produced CTX-M-15/-3 and CMY-4 ß-lactamases. They belonged to ST11 Klebsiella pneumoniae clone. The epidemiology typing revealed three main high-risk K. pneumoniae clones (26%)-ST11, ST258, and ST15 and five main Escherichia coli clones-ST131 (41.7%), ST38, ST95, ST405, and ST69. Sixty-one percent of ST131 isolates were from the highly virulent epidemic clone O25b:H4-ST131. Phylotyping revealed that 69% of E. coli isolates belonged to the virulent B2 and D groups. Almost all (15/16) Enterobacter isolates were identified as E. hormaechei and the most common ST type was ST90. Among all of the isolates, a high ESBL/carbapenemases/plasmid AmpC (32.4%) prevalence was observed. A significant proportion of the isolates (37%) were members of high-risk clones including two pan-drug-resistant K. pneumoniae ST11 NDM-1 producing isolates. Due to extensive antibiotic usage during COVID-19, the situation may worsen, so routine screenings and strict infection control measures should be widely implemented.

Urinary tract infections: Should we think about the anaerobic cocci?

Anaerobic cocci are common anaerobic isolates. Numerous genera of anaerobic cocci have been reported in both urinary tract microbiota, mainly of females, and in cases of urinary tract infections (UTIs), predominantly in patients with comorbidities, when no facultatively anaerobic bacteria were detected from the urine samples. UTIs caused by anaerobic cocci have been reported in >7% in some studies. As the routine diagnostic methods may be insufficient to detect and identify the anaerobic cocci in patients with UTIs, enhanced quantitative urine culture (EQUC) can give better results. EQUC is performed by plating urine samples onto different media to be incubated in both aerobic and anaerobic conditions with a prolonged incubation time. Other newer methods such as 16S rRNA gene sequencing, qualitative PCR and Next Generation Sequencing can also be considered. Anaerobic cocci such as Peptoniphilus, Parvimonas, Anaerococcus and Finegoldia spp. were found in patients with bacteremia of urinary source. A fatal outcome has been reported in a diabetic patient with emphysematous pyelonephritis caused by Finegoldia magna and Candida parapsilosis due to a delay in seeking hospital care during the COVID-19 pandemic. In specific cases such as of chronic infections, immunosuppression, comorbidity, advanced age, following urological tract manipulations and negative culture results for usual uropathogens, it may be advisable to use suprapubic aspiration cultured in both aerobic and anaerobic condition or EQUC using media which support the relative slow growing anaerobic cocci as well.

Gardnerella vaginalis in urinary tract infections, are men spared?

Gardnerella vaginalis in association with anaerobes has been linked to bacterial vaginosis in women, while urinary tract infections (UTIs) in men have rarely been reported. The aim of the review was to reveal the significance of G. vaginalis UTIs in men. Prevalence of G. vaginalis UTIs in men varied from 0.5 to >27% according to patients' groups. Most patients had comorbidity such as urolithiasis or stents, transplants, tumors and diabetes, however, infections can also affect immunocompetent patients. We observed G. vaginalis-associated bacteriuria and leukocyturia in a kidney transplant man. Complications of the UTIs such as bacteremia (in 9/11 cases), hydronephrosis (4/11) and abscesses or septic emboli have been reported. Bacterial vaginosis in female partners has been a risk factor for UTIs in males. In women, biofilm Gardnerella phenotype, stabilized by Atopobium vaginae and Prevotella bivia was linked to ≥6-fold higher antibiotic resistance rates compared with the planktonic phenotype. Non-susceptibility to metronidazole and levofloxacin was found also in males. Therefore, if aerobic urine cultures are negative, urine and blood samples from male patients with predisposing factors and clinical signs of UTIs and bacteremia, can be taken. Plates should be incubated for 2-4 days in capnophilic/microaerophilic conditions, however only anaerobic incubation can help with detecting G. vaginalis strains which grow only anaerobically. Susceptibility testing of the isolates is highly important. Briefly, adherent G. vaginalis phenotype can be sexually transmissible. Despite the infrequency of G. vaginalis UTIs in men, the infections should be considered since they are often linked to severe complications.

Activity of delafloxacin versus that of levofloxacin against anaerobic and microaerophilic isolates.

The aim of the study was to comparatively assess delafloxacin and levofloxacin activities against 96 anaerobic and some microaerophilic isolates. Delafloxacin minimal inhibitory concentrations (MICs) were strikingly lower than those of levofloxacin. Delafloxacin MIC90 against clostridia, other Gram-positive rods, anaerobic/microaerophilic cocci and Gram-negative rods were 0.75, 0.032, 0.38 and 0.5 µg/mL, respectively. The highest (≥4 µg/mL) MICs of the newer fluoroquinolone were found in only 4.2% of isolates versus 46.9% by levofloxacin. The present results and the potency in acidic conditions showed delafloxacin advantages over levofloxacin in terms of usefulness for treatment of mixed anaerobic-aerobic infections and activity against Clostridioides (Clostridium) difficile.

Problematic clinical isolates of Pseudomonas aeruginosa from the university hospitals in Sofia, Bulgaria: current status of antimicrobial resistance and prevailing resistance mechanisms.

A total of 203 clinical isolates of Pseudomonas aeruginosa was collected during 2001-2006 from five university hospitals in Sofia, Bulgaria, to assess the current levels of antimicrobial susceptibility and to evaluate resistance mechanisms to antipseudomonal antimicrobial agents. The antibiotic resistance rates against the following antimicrobials were: carbenicillin 93.1 %, azlocillin 91.6 %, piperacillin 86.2 %, piperacillin/tazobactam 56.8 %, ceftazidime 45.8 %, cefepime 48.9 %, cefpirome 58.2 %, aztreonam 49.8 %, imipenem 42.3 %, meropenem 45.5 %, amikacin 59.1 %, gentamicin 79.7 %, tobramycin 89.6 %, netilmicin 69.6 % and ciprofloxacin 80.3 %. A total of 101 of the studied P. aeruginosa isolates (49.8 %) were multidrug resistant. Structural genes encoding class A and class D beta-lactamases showed the following frequencies: bla(VEB-1) 33.1 %, bla(PSE-1) 22.5 %, bla(PER-1) 0 %, bla(OXA-groupI) 41.3 % and bla(OXA-groupII) 8.8 %. IMP- and VIM-type carbapenemases were not detected. In conclusion, the studied clinical strains of P. aeruginosa were problematic nosocomial pathogens. VEB-1 extended-spectrum beta-lactamases appear to have a significant presence among clinical P. aeruginosa isolates from Sofia. Carbapenem resistance was related to non-enzymic mechanisms such as a deficiency of OprD proteins and active efflux.