Drug-resistant genes and virulence factors of carbepenem-resistant Klebsiella peumoniae / 中华临床感染病杂志

Objective To investigate the resistance mechanism and virulence genes of clinical strains of carbapenem-resistant Klebsiella pneumonia ( CRKP ) .Methods Twenty clinical CRKP strains were collected from Tianjin Medical University General Hospital during May 2014 and May 2015.Vitek-2 Compact system was used for identification of the strains and antibiotic susceptibility test .Modified Hodge Test and EDTA double disk phenotypic test were performed for screening of drug -resistant phenotypes .Drug-resistant genes , capsular serotypes and associated virulence genes were amplified by PCR , and positive products were sequenced and analyzed by DNA sequencing .Results Resistance to beta-lactam antibiotics including cephalosporins and carbapenems was observed in 80.0%and above strains , but more than 70.0%strains were sensitive to tigecycline , amikacin and levofloxacin .KPC gene and NDM gene were found in 7 strains (35.0%) and 8 strains (40.0%), respectively.SHV, the most common extended-spectrumβ-lactamases ( ESBLs ) gene, was found in 16 strains ( 80.0%). DHA plasmid-mediated AmpCβ-lactamase was found in 2 strains (10.0%).Deletions of porin-coding genes OmpK35 and OmpK36 were found in 8 stains ( 40.0%) and 13 strains ( 65.0%), respectively.Carbapenem-resistant genes in combination with ESBLs genes and/or variation of porin was found in 14 strains (70.0%), and ESBLs genes in combination with variation of porin was found in 4 strains (30.0%).Three strains were of capsular serotype K1 and 1 was of K57, and all of them carried KPC genes .Virulence gene rmpA was found in 8 strains and all carried carbapenemases , among which 5 strains with KPC, 2 strains with NDM, 1 strain with both KPC and NDM .Six strains were aerobactin gene positive , among which 4 strains carried KPC genes . FimH-1 was positive in all strains .Conclusions KPC and NDM genes mainly account for resistance in CPKP, and ESBLs with OmpK gene deletion may also be an important cause .Strains with capsular serotypes K1 and K57 carrying KPC genes are common .

Clinical Implications of Pneumococcal Serotypes: Invasive Disease Potential, Clinical Presentations, and Antibiotic Resistance

Streptococcus pneumoniae can asymptomatically colonize the nasopharynx and cause a diverse range of illnesses. This clinical spectrum from colonization to invasive pneumococcal disease (IPD) appears to depend on the pneumococcal capsular serotype rather than the genetic background. According to a literature review, serotypes 1, 4, 5, 7F, 8, 12F, 14, 18C, and 19A are more likely to cause IPD. Although serotypes 1 and 19A are the predominant causes of invasive pneumococcal pneumonia, serotype 14 remains one of the most common etiologic agents of non-bacteremic pneumonia in adults, even after 7-valent pneumococcal conjugate vaccine (PCV7) introduction. Serotypes 1, 3, and 19A pneumococci are likely to cause empyema and hemolytic uremic syndrome. Serotype 1 pneumococcal meningitis is prevalent in the African meningitis belt, with a high fatality rate. In contrast to the capsule type, genotype is more closely associated with antibiotic resistance. CC320/271 strains expressing serotype 19A are multidrug-resistant (MDR) and prevalent worldwide in the era of PCV7. Several clones of MDR serotype 6C pneumococci emerged, and a MDR 6D clone (ST282) has been identified in Korea. Since the pneumococcal epidemiology of capsule types varies geographically and temporally, a nationwide serosurveillance system is vital to establishing appropriate vaccination strategies for each country.

Combined detection of capsule associated protein 10 and virulence-associated DEAD-box RNA helicase 1 in the clinical diagnosis of Cryptococcus neoformans meningitis / 中华传染病杂志

Objective To establish the quantitative detection of capsule associated protein 10 (CAP10)and virulence-associated DEAD-box RNA helicase 1(VAD1)genes in Cryptococcus neoformans (CN) and compare the diagnostic values of single gene test and combined gene test in CN meningitis.MethodsTwenty-three CN meningitis patients with fungal culture or ink staining or CN antigen detection positive in cerebrospinal fluid (CSF) were recruited and patients with craniocerebral trauma were recruited as controls.Standard plasmids were constructed using standard CN strain.Real time fluorescent quantitative polymerase chain reaction (RT-FQ-PCR) was established to detect the mRNA expressions of CAP10 and VAD1 genes in the CSF of patients with CN meningitis,which were compared with the results of CSF ink staining,fungal culture and antigen detection.The diagnostic values of single gene test and combined gene test were compared by chi square test.Results Among 23 CN meningitis patients,22 (95.6％) were CAP10 mRNA positive detected by RT-FQ-PCR,which was significantly higher than both ink staining (16/23,69.6％,x2 =4.167,P＜0.05) and fungal culture (15/23,65.2％,x2=5.143,P＜0.05),respectively; but not significant different from antigen detection (21/23,91.3％,x2=0.500,P＞0.05).There were also no statistical significant differences between combined detection of CAP 10 + VAD1 and CAP 10 or VAD1 single gene test (P＞0.05).ConclusionRT-FQ-PCR detection is successfully established using virulence genes as target,which is superior to the conventional methods.

Study of streptococcus pneumonia capsular polysaccharide antibodies in patients with chronic obstructive pulmonary disease / 中国医师进修杂志

ObjectiveTo study streptococcus pneumonia capsular polysaccharide antibodies of patients with chronic obstructive pulmonary disease(COPD) in acute exacerbation and the feasibility of vaccination for patients with COPD.MethodsThe COPD in acute exacerbation without respiratory failure (RF)(COPD without RF group),COPD in acute exacerbation with RF (COPD with RF group),asthma (asthma group),healthy elderly examination(elderly examination group) and healthy youth examination (youth examination group) were selected,and each group had 15 cases.The levels of streptococcus pneumonia capsular polysaccharide antibodies IgG,IgM and IgA were measured in all groups.Results There was no significant difference in IgG among the five groups (P ＞ 0.05 ).The levels of IgM in COPD without RF group and elderly examination group were significantly lower than those in COPD with RF group,asthma group and youth examination group (0.554 ± 0.309 and 0.538 ± 0.327 vs.0.810 ± 0.387,0.887 ± 0.278 and 0.852 ± 0.305,P ＜ 0.05 ).Although the level of IgA in COPD without RF group was significantly lower than that in youth examination group(0.532 ±0.297 vs.0.930 ±0.502,P ＜0.05),there was no significant difference among the five groups.Conclusion Patients with COPD should inoculate pneumococcal vaccination.