Jiunn-Jong Wu

The emergence of imipenem-resistant Pseudomonas aeruginosa (IRPA) has become a great concern worldwide. The aim of this study was to investigate resistance mechanisms associated with bloodstream isolated IRPA strains in Taiwan. A total of 78 non-duplicated IRPA isolates were isolated from patients with bloodstream infection. The average prevalence of imipenem-resistance in those isolates was 5.9 % during a 10-year longitudinal surveillance in Taiwan. PFGE results showed high clonal diversity among the 78 isolates. VIM-2, VIM-3, OXA-10, and OXA-17 β-lactamases were identified in 2 (2.6 %), 3 (3.8 %), 2 (2.6 %), and 1 (1.3 %) isolates, respectively. Active efflux pumps, AmpC β-lactamase overproduction, and extended-spectrum AmpC cephalosporinases (ESACs) were found in 58 (74.4 %), 25 (32.1 %) and 15 (19.2 %) of IRPA isolates, respectively. oprD mutations with amino acid substitution, shortened putative loop L7, premature stop codon caused by point mutation, frameshift by nucleotide insertion or deletion, and interruption by insertion sequence were found in 19 (24.4 %), 18 (23.1 %), 15 (19.2 %), 14 (17.9 %), and 10 (12.8 %) of isolates, respectively. This study suggests that alterations in the OprD protein and having an active efflux pump are the main mechanisms associated with bloodstream isolated IRPA. Overproduction of AmpC, ESACs, and the presence of VIM- and OXA-type β-lactamases play additional roles in reduced susceptibility to imipenem in P. aeruginosa isolates in Taiwan.

To evaluate the curative effect of external lumbar drainage combined with empirical antibiotics treatment on the postoperative culture negative meningitis. The clinical data of eighty post-operative meningitis patients with cerebrospinal fluid culture negative were retrospectively analyzed according to inclusive and exclusive criteria from January 2013 to December 2014 in Department of Neurosurgery, Tianjin Huanhu Hospital. All patients were composed of 45 male cases and 35 female cases, aging from 9 to 72 years. All patients were divided into two groups according to receiving the different treatment: one group only receiving a intravenously empirical antibiotics treatment (n=40), another group receiving a combined therapy of external lumbar drainage and intravenously empirical antibiotics treatment (n=40). The volume of drainage of cerebrospinal fluid (CSF) were set up from 200 to 300 ml per day. There was no difference in the dosage and interval of the same antibiotics between two groups. The antibiotics usage and therapeutic effect of two groups of patients were observed and analyzed by t-test, Wilcoxon rank test or χ(2) test. The rate of CSF bacterial culture negative was 62.9% (88/140) in the same period. In group of empirical antibiotics treatment, the time of antibiotics treatment was (12.6±3.1) days, the rate of combined with other antibiotics treatment was 40.0% (16/40), the rate of mortality was 15.0% (6/40). However, in group of external lumbar drainage combined with empirical antibiotics treatment, the 3 data were (5.3±1.2) days, 10.0% (4/40), 7.5% (3/40), respectively. The time of antibiotics of the group of empirical antibiotics was longer (t=3.605, P=0.017), while the rate of combined antibiotics and the rate of mortality were lower (χ(2)=3.971, P=0.035; χ(2)=4.136, P=0.027, respectively). The average drainage time was (5.8±1.5) days, 32 patients gained a complete healing only by their first placement, 5 cases need replacement because of occlusion or drainage time more than 14 days. There were no recurrence cases after 3 months' follow-up. The method of external lumbar drainage combined with empirical antibiotics treatment can significantly reduce the dosage and course of antibiotics treatment. It is a simple, safe, efficacious method for the treatment of neurosurgical postoperative bacterial culture negative meningitis.

Matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) and conventional standard methods were compared for time to pathogen identification and impact on clinical outcomes in peritoneal dialysis-related peritonitis patients. The MALDI-TOF MS method identified the causative microorganisms earlier (average time saved, 64 h for all pathogens), and patients had a shorter hospital stay (mean ± standard deviation, 5.2 ± 4.8 days versus 8.2 ± 4.5 days, P = 0.001).

emm typing is the most widely used molecular typing method for the human pathogen Streptococcus pyogenes (group A streptococcus [GAS]). emm typing is based on a small variable region of the emm gene; however, the emm cluster typing system defines GAS types according to the nearly complete sequence of the emm gene. Therefore, emm cluster typing is considered to provide more information regarding the functional and structural properties of M proteins in different emm types of GAS. In the present study, 677 isolates collected between 1994 and 2008 in a hospital in southern Taiwan were analyzed by the emm cluster typing system. emm clusters A-C4, E1, E6, and A-C3 were the most prevalent emm cluster types and accounted for 67.4% of total isolates. emm clusters A-C4 and E1 were associated with noninvasive diseases, whereas E6 was significantly associated with both invasive and noninvasive manifestations. In addition, emm clusters D4, E2, and E3 were significantly associated with invasive manifestations. Furthermore, we found that the functional properties of M protein, including low fibrinogen-binding and high IgG-binding activities, were correlated significantly with invasive manifestations. In summary, the present study provides updated epidemiological information on GAS emm cluster types in southern Taiwan.

Clustered regularly interspaced short palindromic repeats (CRISPR) are the bacterial adaptive immune system against foreign nucleic acids. Given the variable nature of CRISPR, it could be a good marker for molecular epidemiology. Group A streptococcus is one of the major human pathogens. It has two CRISPR loci, including CRISPR01 and CRISPR02. The aim of this study was to analyze the distribution of CRISPR-associated gene cassettes (cas) and CRISPR arrays in highly prevalent emm types. The cas cassette and CRISPR array in two CRISPR loci were analyzed in a total of 332 strains, including emm1, emm3, emm4, emm12, and emm28 strains. The CRISPR type was defined by the spacer content of each CRISPR array. All strains had at least one cas cassette or CRISPR array. More than 90% of the spacers were found in one emm type, specifically. Comparing the consistency between emm and CRISPR types by Simpson’s index of diversity and the adjusted Wallace coefficient, CRISPR01 type was concordant to emm type, and CRISPR02 showed unidirectional congruence to emm type, suggesting that at least for the majority of isolates causing infection in high income countries, the emm type can be inferred from CRISPR analysis, which can further discriminate isolates sharing the same emm type.