Molecular characteristics of the omp A gene of serotype B Chlamydia trachomatis in Qinghai Tibetan primary school students

To study the molecular characteristics of Chlamydia trachomatis, the major outer membrane protein gene(omp A) of C. trachomatis from primary school students with trachoma residing in the Qinghai Tibetan area was sequenced and compared with the same serotype in Gen Bank. In Jianshetang Primary School and Galeng Central Primary School in the Galeng Tibetan Township of Qinghai Haidong Sala Autonomous County, scraped samples were collected from the upper tarsal conjunctiva and lower conjunctival sac of both eyes of 45 students with trachoma, stored at 4°C, and transported to Beijing Tongren Hospital by air within 24 h. The samples were screened for C. trachomatis by real-time PCR. The omp A gene from the C. trachomatis-positive samples was amplified by nested PCR. The serotype was confirmed by National Center for Biotechnology Information(NCBI) BLAST search and homology analysis. The entire omp A gene sequence was compared with the corresponding gene sequences of serotype B strains available in Gen Bank. Of the 45 students aged 6–13 years with trachoma, 26 C. trachomatis-positive students were identified by the initial real-time PCR screening(average age,(9.09±1.63) years; sex ratio, 1.0), accounting for 57.78%(26/45). The cycle threshold values for real-time PCR were 16.79–37.77. Half(13/26) of C. trachomatis-positive students had a bacterial copy number of >105. The compliance rate of the omp A gene sequences with the C. trachomatis serotype B strains in Gen Bank was up to 99%. Two novel genetic mutations were found when the omp A gene was compared with those of the 11 serotype B strains in Gen Bank. The two non-synonymous mutations were located at(i) position 271 in the second constant domain, an adenine(A) to guanine(G) substitution(ACT?GCT), changing the amino acid at position 91 from threonine to alanine(Thr?Ala) in all 26 strains; and(ii) position 887 in the fourth variable domain, a cytosine(C) to thymine(T) substitution(GCA?GTA), changing the amino acid at residue 296 from alanine to valine(Ala?Val) in four of the 26 strains. Six mutations were identified relative to ATCC VR-573. The strains could be divided into two gene clusters according to the mutation at nucleotide position 887: CQZ-1(China Qinghai Tibetan-1) and CQZ-2(China Qinghai Tibetan-2). We thus detected two novel serotype B mutant strains of C. trachomatis among study subjects with trachoma.

Characteristics of pathogenic microorganisms found in 99 cases of conjunctivitis from the Qinghai Tibetan area

Dear Editor,Morbidity associated with conjunctivitis is higher in developing countries,particularly among children,because of the poorer standards of living(Azari and Barney,2013;Yetman and Coody,1997).Presently,little is known regarding the microorganisms that cause conjunctivitis in the remote area of Chinese Tibet.In particular,it is difficult to monitor and control the occurrence of conjunctivitis in children from this area.Conjunctivitis has two forms:acute and chronic.

Study of infectious conjunctivitis among children in rural areas of Qinghai province

Infectious conjunctivitis is no longer a common eye disease in cities and developed areas, but in remote mountainous regions of China where living conditions are relatively under-developed, the occurrence of infectious conjunctivitis remains a public health issue. Here, we evaluate the ratio of infectious conjunctivitis among primary school students in the rural areas of Xunhua, Huangyuan, and Huzhu Counties in the Qinghai province of China, and report the microorganisms involved in causing infection. Of the 765 eligible primary school students, 694 participated to this study(a response rateof 90.7%), 381 boys and 313 girls, with a mean age of 7.52 years(range 7–9 years). A clinical diagnosis of infectious conjunctivitis was returned for 238 of the 694 children examined. The ratio of infectious conjunctivitis in Xunhua County(46.64%) was higher compared to that in Huangyuan(26.67%; P=0.03) and Huzhu Counties(23.61%; P=0.02). The leading cause of conjunctivitis was bacterial, followed by chlamydial and viral. Our results show that there is a high ratio of infectious conjunctivitis among rural primary school students in Qinghai province.

Mechanism study of trans-lamina cribrosa pressure difference correlated to optic neuropathy in individuals with glaucoma

Glaucoma is the second leading cause of blindness after cataract worldwide.However,among irreversible blinding eye diseases,glaucoma is the primary cause(Liang et al.,2011).To date,most studies have indicated that glaucoma is not only an ocular disease,but also an optic nerve disease.In particular,primary open-angle glaucoma(POAG)is characterized by insidious onset,painless visual impairment,and complicated pathological mechanism,and patients with such condition require long-term follow-up.However,the underlying cause of POAG remains unclear,and there are several theories about its exact etiology.Some mechanisms have presented underlying optic nerve damage,which include the mechanical theory,vascular theory,and the in・volvement of other factors.