Protective effects of different lyoprotectants on survival of clinical bacterial isolates in a hospital biobank.

Nowadays the significant role of biobanks in medical, diagnostic, industrial, and environmental research is well known. Bacterial biobanks could be used as a good resource for designing new treatments, biomedical and industrial researches, and laboratory diagnostics. To have a collection of bacteria from clinical samples and maintain their long-term viability, their preservation needs appropriate protective agents, like cryoprotectants and lyoprotectants. In this study, we collected and characterized Gram-negative and Gram-positive bacteria carrying important antibiotic resistance markers from different clinical samples of hospitalized children. Sucrose (10%), skimmed milk (10%), skimmed milk plus sodium glutamate (10% + 1%), and bovine serum albumin (BSA, 10%) were used as lyoprotectants during the freeze-drying procedure. The survival rate of the lyophilized samples was calculated by dilution plating and measuring the colony forming unit (CFU) after 3 months of storage. The culture analysis results indicated that 25 of the 27 studied bacterial genera (Dilutions 10-3 to 10-6), including Shigella, Methicillin-resistant S. aureus, Acinetobacter spp., Escherichia spp., Pseudomonas spp., Klebsiella spp., Enterococcus spp., were recovered in cultured fractions from all preservation conditions, while 2 genera were only detected in a single preservation condition (2/27, 7.4%). Based on the results, sucrose (10%) and skimmed milk (10%) presented the most protective features. The survival rates varied significantly according to types of the bacteria. Collectively, our results showed a diversity in the recovery of different bacterial genera after lyophilization. While statistically no significant difference was detected among the studied protective agents, sucrose (10%) and skimmed milk (10%) exhibited more effective lyoprotective properties for both Gram-positive and Gram-negative bacteria among the clinical isolates in our study.

Characterization of Sequence Types and Mechanisms of Resistance to Tigecycline Among Acinetobacter baumannii Isolated from Children.

The present study aimed to investigate the mechanisms of resistance to tigecycline and to determine sequence types of Acinetobacter baumannii isolates recovered from children, using the Multilocus Sequence Typing (MLST). A total of 74 A. baumannii isolates were recovered from patients at one of the children's hospital in Tehran, Iran. Antimicrobial susceptibility testing of the isolates was performed for different classes of antibiotics and minimum inhibitory concentrations of colistin and tigecycline were determined using broth microdilution method and E-test strips, respectively. The presence of ISAba1, AbaR, tet(39), and tetX and the expressions of adeB, adeG, and adeJ efflux pump genes were measured using Polymerase Chain Reaction (PCR) and quantitative real-time PCR (RT-PCR), respectively. The diversity of mutations across the regulatory genes of RND efflux pumps (adeRS, adeL, and adeN) and trm gene were determined using their PCR amplification and DNA sequencing in tigecycline-resistant isolates. In addition, STs of tigecycline-resistant isolates were determined using MLST method. Three A. baumannii isolates were resistant to tigecycline. Several amino acid substitutions were identified in AdeRS, AdeN, and Trm but no alteration was found in AdeL. Nevertheless, adeB, adeG, and adeJ overexpression were observed in 1, 2, and 1 isolates, respectively. The tigecycline-resistant isolates belonged to ST1720 and ST2285. This is the first study reporting on ST2285 in A. baumannii populations. Among 74 isolates, two tigecycline susceptible isolates carried tet(39) gene but no tetX gene was detected. We concluded that mutations in regulatory genes of RND efflux pumps and the trm gene may play some important role in A. baumannii resistance to tigecycline.

Efficacy of 2% metronidazole gel in moderate acne vulgaris.

BACKGROUND: Acne vulgaris is an inflammatory disease of the pilosebaceous units. Various systemic and topical options are available for its treatment. AIMS: This study aimed to evaluate the efficacy of 2% metronidazole gel in acne vulgaris. MATERIALS AND METHODS: Double-blind, randomized, placebo-controlled, split-face clinical trial. Seventy young adults with moderate acne vulgaris received 2% metronidazole gel on the right side of their face and placebo on the left side of their face twice daily for 8 weeks. The number of inflamed and noninflamed facial lesions and side effects of treatment were documented on weeks 1, 2, 4, and 8. The patients' overall satisfaction was recorded at the end of the study. For statistical analysis we used the repeated-measures analysis, the chi-square test, Fisher's exact test, and the independent-samples t-test as appropriate. RESULTS: Counts of inflamed and noninflamed facial lesions were comparable between the two sides at baseline. The number of the lesions was significantly lower on the metronidazole-treated side at all follow-up visits. Erythema and oily face decreased by 85.7% and 87.1%, respectively, on the metronidazole-treated side. Mild burning sensation and dryness on the metronidazole-treated side was reported by 3.4% and 22.9% of the patients, respectively. Eighty-eight percent of the patients were satisfied with the results of treatment on the metronidazole-treated side. CONCLUSIONS: Metronidazole gel (2%) is an effective, safe, and well-tolerated topical medication for moderate acne vulgaris.