Determination of the Genetic Diversity of Different Bioluminescent Bacteria by Pulsed-Field Gel Electrophoresis (PFGE)

The Wound Microbiology and the Outcomes of the Systemic Antibiotic Prophylaxis in a Mass Burn Casualty Incident

This paper describes the wound microbiology and outcome of using systemic antibiotic prophylaxis (SAP) in mass burn casualties (MBC). The charts of 31 patients (mean age: 21 years, mean burn area: 42% of the total body surface area) injured in a dust explosion were reviewed for 1 month after the burn. Polymicrobial and rare pathogen wound infections (Acinetobacter junii, Aeromonas sobri, et al) were common in MBC due to sterility breech. Following the use of SAP for 2 to 14 days after admission, there was a reduction in wound infection rate from 45% at week 1 postburn to 10% at week 4. In addition, no blood stream infection occurred in the first week after the burns. Multidrug-resistant Acinetobacter baumannii, Klebsiella pneumoniae, and Candida albicans were the top three wound pathogens cultured. Multidrug-resistant microorganism infections were found in 39% of the patients, and the odds ratios for the these infections in burn patients with more than ≥40% total body surface area and in patients receiving two or more classes of antibiotics were 41.7 (95% confidence interval [CI] = 2.1-810.7, P = .01) and 9.9 (95% CI= 1.0-92.7, P = .04), respectively. Although SAP did not prevent wound or blood stream infections, no mortality occurred in our patients. A randomized controlled study is needed to investigate the impact of SAP on burn mortality in MBC.

First Study of Antimicrobial Activity of Ceftazidime-Avibactam and Ceftolozane-Tazobactam Against Pseudomonas aeruginosa Isolated from Patients with Urinary Tract Infection in Tehran, Iran

Purpose

Pseudomonas aeruginosa causes complicated and/or nosocomial UTI. These infections are usually associated with severe and multi-drug resistant P. aeruginosa isolates. As there is no study about the activity of novel antibiotics ceftazidime-avibactam (CZA) and ceftolozane-tazobactam (C/T) against P. aeruginosa isolates in Iran, we aimed to evaluate for the first time the efficacy of these agents against P. aeruginosa isolated from patients with UTI in Iran. Then, the genetic diversity of the resistant isolates was assayed.

Methods

In this study, a total of 200 P. aeruginosa isolates were collected from patients with UTI in Tehran, Iran. Disk diffusion and Minimum Inhibitory Concentration (MIC) methods were applied to determine the resistance of the isolates to CZA, C/T, and the other antibiotics. Extended-spectrum β-lactamases (ESBLs) and Metallo Beta Lactamase (MBL) production were assayed by Combination disk diffusion test (CDDT). Polymerase chain reaction (PCR) was carried out to detect the resistance genes, including beta-lactamases and carbapenemases genes. Finally, genomic analysis of the isolates was performed using the Pulse field gel electrophoresis (PFGE).

Results

Among the isolates, 16 (8%) were resistant to CZA and C/T that MIC confirmed it. The resistant isolates showed high resistance to the other classes of antibiotics. Among the resistant isolates, 31.2% and 75% were ESBL and MBL producers, respectively. The prevalence of bla_OXA10, bla_VIM, bla_OXA48, bla_OXA2, and bla_CTX-M was 100%, 50%, 31.2%, 25%, and 12.5%. Furthermore, two isolates (12.5%) harbored bla_PER and bla_NDM genes. The resistant isolates were grouped into 14 distinct pulsotypes and two shared pulsotypes were found.

Conclusion

Ceftazidime-avibactam and ceftolozane-tazobactam showed high activity against the P. aeruginosa isolated from patients with UTI in Iran. The low rate of resistance to the antibiotics is also alarming and should be considered to avoid further spreading of the antibiotic resistance among the P. aeruginosa and the other bacteria.

Epidemiological and Molecular Investigations on Salmonella Responsible for Gastrointestinal Infections in the Southwest of Shanghai From 1998 to 2017

Purpose

To investigate the characteristics of gastrointestinal infections in Southwest Shanghai.

Methods

Clinical and epidemiological characteristics of patients with Salmonella infections between 1998 and 2017 admitted to the Jinshan Hospital in the Southwest of Shanghai were retrospectively analyzed. A total of 565 isolated Salmonella strains were classified by serotyping and pulsed field gel electrophoresis (PFGE).

Results

From 1998 to 2006, diarrhea was mainly caused by Vibrio parahaemolyticus followed by Shigella and Salmonella. From 2007 to 2010, Vibrio parahaemolyticus infection was the major cause of diarrhea followed by Salmonella and Shigella. From 2011 to 2017, Salmonella infections became the main cause of diarrhea after Vibrio parahaemolyticus. Salmonella infections increased from 2006 on and peaked between May and October, accounting for 82.48% of yearly infections. Patients with Salmonella infections (90.5%) had a history of eating unclean food, abdominal pain (58.05%), diarrhea ≥5 times a day (50.44%), moderate fever (24.96%) and increased fecal leukocytes (41.42%). From 1998 to 2017, infected specimens from clinical cases were dominated by Salmonella enterica serovar Typhimurium (S. Typhimurium) (21.59%) followed by Salmonella enterica serovar Enteritis (S. Enteritidis) (16.81%), Salmonella enterica serotype London (6.55%) and Salmonella group B (13.10%). Other species included Salmonella enterica serovar Thompson, Salmonella enterica serovar Saintpaul, Salmonella group D, Salmonella group C, Salmonella enterica serovar Choleraesuis and Salmonella enterica serovar Aberdeen. The PFGE classification of Salmonella serovars in 2008–2017 demonstrated that S. Enteritidis had 9 PFGE banding patterns and S. Typhimurium 16 with varying degrees of similarity among S. Enteritidis and S. Typhimurium. The results of antibiotic susceptibility tests for the 330 Salmonella strains revealed that fosfomycin had the highest sensitivity rate (97.5%) followed by levofloxacin and ceftriaxone (81%), and ampicillin/sulbactam (78.2%). The resistance to piperacillin and ciprofloxacin was 60.9 and 50.61%, respectively.

Conclusion

The features of onset, epidemiological characteristics and molecular subtyping of Salmonella were conducive to clinical diagnosis, rational use of antibiotics and improved therapeutic efficacy.