Novel Providencia xianensis sp. nov.: A multidrug-resistant species identified in clinical infections.

Providencia genus is known to harbor certain opportunistic pathogens capable of causing human infections. Here, we report two strains of multidrug-resistant bacteria initially identified as Providencia rettgeri by mass spectrometry, but genome analysis revealed their ANI (79.84-84.20%) and dDDH (21.1-25.6%) values to fall below the accepted species threshold for known Providencia species. We therefore propose that these isolates be recognized as a novel species, Providencia xianensis sp. nov. Alarmingly, both strains, isolated from locations far apart, exhibited resistance to last-resort antibiotics, indicating their possible wide distribution, underscoring the urgency for immediate attention and enhanced surveillance for this emerging multidrug-resistant pathogen.

Antibacterial activities of inorganic agents on six bacteria associated with oral infections by two susceptibility tests.

The antibacterial effects of six inorganic antibacterial agents were assessed using broth dilution and agar dilution tests on six pathogenic bacteria associated with oral infectious diseases: Streptococcus mutans (ATCC 25175), S. mutans (Ingbritt), Actinomyces viscosus (ATCC 15987), Lactobacillus casei (ATCC 393), Staphylococcus aureus (ATCC 29213) and Candida albicans (ATCC 90028). The results of the broth dilution test were significantly lower than those of the agar dilution test (F=38.290; P<0.01). The six inorganic agents notably inhibited the growth of tested common oral bacteria in vitro. Among them, Longbei inorganic antibiotic powder was the strongest antibacterial agent, followed by ZnO whisker antibacterial complex (ZnOw) AT-83, IONPURE-H, basic magnesium hypochlorite, ZnOw AT-88 and Antim-AMS2. The broth dilution test appears to be more suitable for testing insoluble inorganic agents.

An outbreak of a nosocomial NDM-1-producing Klebsiella pneumoniae ST147 at a teaching hospital in mainland China.

A total of 1,870 nonduplicate clinical Enterobacteriaceae from 13 teaching hospitals located in 11 provinces of mainland China from 2011 to 2012 were screened for the presence of the blaNDM gene. The high-throughput MiSeq sequencing method and comparative genomics were used to analyze the genetic environment of blaNDM among these isolates. Three blaNDM-1-carrying Klebsiella pneumoniae (0.16%, 3/1,870), isolated from a teaching hospital in Xi'an, exhibited high levels of resistance to all ß-lactams, but remained susceptible to amikacin, tigecycline, and polymyxin B. These three isolates, belonging to ST147, presented an identical pulsed-field gel electrophoresis pattern. The IncX3 plasmid, pNDM-SX04 (KC876051) showed 99% identity with plasmid pNDM-HN380 (JX104760). Comparative analysis of the genetic environment of blaNDM-1 with previously published plasmids revealed the same 7,830-bp basic mobile element, which may have been derived from Acinetobacter spp. Partial ISAba125, ISAba125 promoter, blaNDM-1, and bleMBL could serve as the minimal mobile vehicle facilitating horizontal transfer of the blaNDM-1 gene. To our knowledge, this is the first report of an outbreak of blaNDM-1-carrying ST147 K. pneumoniae. Although the prevalence spread by the blaNDM-1 gene prevalence is at a low frequency in mainland China, a dynamic national surveillance of this gene is needed due to its potential transferability.

In vitro drug resistance of clinical isolated Brucella against antimicrobial agents.

OBJECTIVE: To explore the antibiotic resistance of Brucella melitensis and instruct rational use of antimicrobial agents in clinical treatment of Brucella infection. METHODS: Bacteria were cultured and identified by BACTEC9120 and VITEK II automicrobic system. E-test was used to detect the minimal inhibitory concentration (MIC) of antimicrobial agents in the drug susceptivity experiment. RESULTS: A total of 19 brucella strains (all Brucella melitensis) were isolated from 19 patients, who had fever between January 2010 and June 2012, and 17 samples were blood, one was bone marrow, the other sample was cerebrospinal fluid. The MIC range of ceftazidime was 2.0-8.0 mg/L, rifampicin was 0.06-2.0 mg/L, amikacin was 4.0-12.0 mg/L, levofloxacin was 2.0-8.0 mg/L, doxycycline was 8.0-32.0 mg/L, sulfamethoxazole-trimethoprim was 4.0-16.0 mg/L, ampicillin was 1.5-2.0 mg/L and gentamicin was 0.50-0.75 mg/L. CONCLUSIONS: The drugs used in this experiment cover common drugs for treating Brucella. Meanwhile, the results are consistent with clinical efficacy. It is suggested personalized regimen according to patients' status in treatment of Brucella.