Hormones Can Influence Antibiotic Susceptibilities Even in Mono- and Co-Culture Conditions

Pseudomonas aeruginosa and Staphylococcus aureus are known as important nosocomial infectious agents also their co-infections are commonly seen in some patient groups. It is well known that host factors such as hormones have roles in modulation of growth, pathogenesis and susceptibilities to antimicrobials. In our study, the influences of norepinephrine (NE) and melatonin (MEL) on antibiotic susceptibilities were examined in mono and co-culture conditions. Methicilin resistant Staphylococcus aureus (MRSA) ATCC 43300 and Pseudomonas aeruginosa ATCC 27853 were investigated to determine the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC) of ciprofloxacin and gentamicin in the absence/presence of NE (0.0017 and 0.04μg/mL) and MEL (6 and 60 pg/mL) by microdilution method in mono and co-culture. It was found that hormones decreased (among 2-64 fold) MIC and MBC values of both antibiotics for MRSA. However, it was shown that hormones had no effect on MIC values of both antibiotics for P. aeruginosa. MIC and MBC values of both antibiotics for co-culture were found to be reduced compared to monoculture of MRSA; were found to be increased compared to monoculture of P. aeruginosa. Whereas, hormones decreased MIC values of both antibiotics in co-culture conditions. Our results suggest that both hormones decreased MIC values and it seems that hormones could influence antibiotic susceptibilities in a strain-dependent manner.

Speciation and Antibiotic Susceptibilities of Coagulase Negative Staphylococci Isolated from Ocular Infections

Coagulase-negative staphylococci (CoNS) are frequently occurring ocular opportunistic pathogens that are not easily identifiable to the species level. The goal of this study was to speciate CoNS and document antibiotic susceptibilities from cases of endophthalmitis (n = 50), keratitis (n = 50), and conjunctivitis/blepharitis (n = 50) for empiric therapy. All 150 isolates of CoNS were speciated using (1) API Staph (biochemical system), (2) Biolog GEN III Microplates (phenotypic substrate system), and (3) DNA sequencing of the sodA gene. Disk diffusion antibiotic susceptibilities for topical and intravitreal treatment were determined based on serum standards. CoNS identification to the species level by all three methods indicated that S. epidermidis was the predominant species of CoNS isolated from cases of endophthalmitis (84–90%), keratitis (80–86%), and conjunctivitis/blepharitis (62–68%). Identifications indicated different distributions of CoNS species among endophthalmitis (6), keratitis (10), and conjunctivitis/blepharitis (13). Antibiotic susceptibility profiles support empiric treatment of endophthalmitis with vancomycin, and keratitis treatment with cefazolin or vancomycin. There was no clear antibiotic choice for conjunctivitis/blepharitis. S. epidermidis was the most frequently found CoNS ocular pathogen, and infection by other CoNS appears to be less specific and random. Antibiotic resistance does not appear to be a serious problem associated with CoNS.

Investigation of antibiotic susceptibilities of Brucella Strains isolated from various clinical samples in eastern Turkey

Background Brucellosis is a worldwide zoonotic disease that causes serious public health problems. This study aimed to identify Brucella strains isolated from various clinical samples by conventional and molecular methods and to determine antimicrobial susceptibilities against doxycycline (DOX), streptomycin (STR), ciprofloxacin (CIP) and rifampicin (RIF) by the gradient strip (E test) test method. Methods A total of 87 Brucella strains isolated from various clinical specimens between 2004 and 2018 were included in this study. While four of the 87 strains included in the study were identified only at the genus level, the remaining 83 strains were identified at the species level by the Real-Time Multiplex PCR (M-RT-PCR) method and conventional methods were used for biotyping. Results According to molecular identification results, 83 strains were identified as B. melitensis by the M-RT-PCR method, with 82 strains identified as Brucella melitensis biovar (bv) 3 and one as B. melitensis bv 1 according to the conventional biotyping method. Among the antibiotics studied, CIP was found to be the most active agent according to the minimum inhibitory concentrations (MIC)90 values. This was followed by DOX and STR, respectively. While all of the isolates were sensitive to CIP, DOX and STR, 18 (20.7%) strains were found to be moderately susceptible to RIF, with the highest values of MIC50 and MIC90. Conclusions In our study, all strains were identified as B. melitensis. DOX, STR, CIP and RIF used in the treatment of brucellosis were found to be effective.

Development of a provincial interactive antibiogram tool for Ontario

Background: Antimicrobial resistance (AMR) is a public health issue with significant impact on health care. Antibiogram development and deployment is a key strategy for managing and preventing AMR. Our objective was to develop an Ontario antibiogram as part of a larger provincial initiative aimed at advancing antimicrobial stewardship in the province. Methods: As part of a voluntary provincial online survey, antibiogram data from 100 of 201 (49.8%) Ontario hospitals were collected and included. All hospitals in Ontario were eligible to participate except those providing only mental health or ambulatory services. Weighted provincial and regional antibiotic susceptibilities (percentages) were conducted using descriptive statistical analyses, and an interactive antibiogram spreadsheet was developed. Respondent-identified barriers to collecting and interpreting antibiogram data are presented descriptively. Results: There was wide regional variability in antimicrobial-resistant organisms across Ontario. Provincial methicillin-resistant Staphylococcus aureus prevalence was 24.6%, ranging from 5.9% to 43.7% regionally. Provincial Escherichia coli resistance to ceftriaxone and ciprofloxacin was 13.8% (regional range 6.0%–25.1%) and 22.5% (regional range 9.8–37.8%), respectively. Klebsiella spp. resistance to ceftriaxone and ciprofloxacin was similar across all health regions, with overall provincial rates of 7.5% and 5.6%, respectively. Conclusions: We have demonstrated that integrating hospital AMR tracking and reporting as part of a larger voluntary provincial antimicrobial stewardship program initiative is a feasible approach to capturing AMR data. The provincial antibiogram serves as a benchmark for the current state of AMR provincially and across health regions.

Preoperative and Intraoperative Culture Results of Patients with Chronic Otitis Media; Is Culture Swab Reliable?

Objective: The aim of this study was to analyze the culture antibiogram results of samples obtained directly from the middle ear and/or mastoid cells in the operating room, and from the external auditory canal in the outpatient. Methods: This study was conducted between 2016-2018 in Microbiology and Otorhinolaryngology Department. Swab cultures were obtained through the external ear canal preoperatively in outpatients. Middle ear swabs and mastoid granulation tissue were collected intraoperatively, respectively. Demographic datas, bacterial identifications and antibiotic susceptibilities were compared in both groups. Results: Two hundred thirty eight patients with chronic otitis media were enrolled in the study. Out of the 238 cases, 86 patients had negative culture results. P. aeruginosa (n=44), Coagulase Negative Staphylococcus (n=33), S. aureus (n=27), Proteus mirabilis (n=16) and E. coli (n=10) were the most common grown bacteria in both groups. Most common identified groups were Gram-positive bacteria (n=92), non-fermenter Gram-negative bacteria (n=55) and Enterobactericeae (n=42). Gram-positive cocci were higher in outpatient group, whereas Enterobactericeae were higher in intraoperative group (p<0.05). Antibiotic susceptibilities of P. aeruginosa and S. aureus were found to be lower especially in the preoperative group (p <0.05). Conclusion: P. aeruginosa was the most common bacteria in both preoperative and intraoperative cultures and high ciprofloxacin resistance of the isolates were remarkable. Although contamination is an issue in samples collected from the external ear canal of outpatients using cotton swabs, similar microorganisms grew in outpatient and intraoperative cultures

Posttraumatic Bacillus cereus Endophthalmitis: Clinical Characteristics and Antibiotic Susceptibilities

Purpose. To report the clinical characteristics, antibiotic susceptibilities, and visual outcomes of patients with posttraumatic endophthalmitis caused by Bacillus cereus. Methods. In this retrospective, noncomparative case series, the medical records of eyes with culture-proven Bacillus cereus endophthalmitis treated from January 2016 to December 2019 at a referral center were reviewed. Clinical features, antibiotic susceptibilities, and visual outcomes were assessed. Results. A total of 19 eyes of 19 patients were identified. Three patients progressed to orbital cellulitis. Vitrectomy was performed in 13 eyes, and 11 required silicone oil tamponade. Finally, seven eyes underwent silicone oil removal surgery during follow-up. Only two patients retained a visual acuity better than FC. Four patients underwent evisceration, and three patients had NLP. The cultured Bacillus cereus was sensitive to levofloxacin, ofloxacin, tobramycin, and neomycin at 100%. Conclusions. The visual outcomes of posttraumatic Bacillus cereus endophthalmitis were generally poor regardless of the prophylactic and therapeutic measures administered. Vitrectomy combined with silicone oil tamponade could help to save the eyeball. Bacillus cereus has a good susceptibility to ofloxacin, levofloxacin, tobramycin, and neomycin; therefore, fluoroquinolones and aminoglycosides can be used to treat Bacillus cereus infection.