Effects of ppk1 deletion on the drug susceptibility of uropathogenic Escherichia coli producing ESBLs / 中华预防医学杂志

To investigate the effect and the mechanism of ppk1 gene deletion on the drug susceptibility of uropathogenic Escherichia coli producing extended-spectrum beta-lactamases (ESBLs-UPEC). The study was an experimental study. From March to April 2021, a strain of ESBLs-UPEC (genotype was TEM combined with CTX-M-14) named as UE210113, was isolated from urine sample of the patient with urinary tract infection in the Laboratory Department of Guangzhou Eighth People's Hospital, meanwhile its ppk1 gene knock-out strain Δpk1 and complemented strain Δpk1-C were constructed by suicide plasmid homologous recombination technique, which was used to study the effect of ppk1 gene on ESBLs-UPEC drug sensitivity and its mechanism. The drug susceptibility of UE210113, Δpk1, and Δpk1-C were measured by Vitek2 Compact System and broth microdilution method. The quantitative expression of ESBLs, outer membrane protein and multidrug efflux systems encoding genes of UE210113, Δpk1 and Δpk1-C were performed by using qRT-PCR analysis. By using two independent sample Mann-Whitney U test, the drug susceptibility results showed that, compared with UE210113 strain, the sensitivities of Δpk1 to ceftazidime, cefepime, tobramycin, minocycline and cotrimoxazole were enhanced (Z=-2.121,P<0.05;Z=-2.236,P<0.05;Z=-2.236,P<0.05;Z=-2.121,P<0.05), and the drug susceptibility of Δpk1-C restored to the same as which of UE210113 (Z=0,P>0.05). The expression levels of ESBLs-enconding genes blaTEM and blaCTX-M-14 in Δpk1 were significantly down-regulated compared with UE210113, but the expression was not restored in Δpk1-C. The expression of outer membrane protein gene omp F in Δpk1 was significantly up-regulated, while the expression of omp A and omp C were down-regulated. The results showed that the expression of multidrug efflux systems encoding genes tol C, mdt A and mdtG were down-regulated in Δpk1 compared with UE210113. The expression of all of the outer membrane protein genes and the multidrug efflux systems genes were restored in Δpk1-C. In conclusion,the lost of ppk1 gene can affect the expression of the outer membrane protein and multidrug efflux systems encoding genes of ESBLs-UPEC, which increase the sensitivity of ESBLs-UPEC to various drugs.

Effects of ppk1 deletion on the drug susceptibility of uropathogenic Escherichia coli producing ESBLs / 中华预防医学杂志

To investigate the effect and the mechanism of ppk1 gene deletion on the drug susceptibility of uropathogenic Escherichia coli producing extended-spectrum beta-lactamases (ESBLs-UPEC). The study was an experimental study. From March to April 2021, a strain of ESBLs-UPEC (genotype was TEM combined with CTX-M-14) named as UE210113, was isolated from urine sample of the patient with urinary tract infection in the Laboratory Department of Guangzhou Eighth People's Hospital, meanwhile its ppk1 gene knock-out strain Δpk1 and complemented strain Δpk1-C were constructed by suicide plasmid homologous recombination technique, which was used to study the effect of ppk1 gene on ESBLs-UPEC drug sensitivity and its mechanism. The drug susceptibility of UE210113, Δpk1, and Δpk1-C were measured by Vitek2 Compact System and broth microdilution method. The quantitative expression of ESBLs, outer membrane protein and multidrug efflux systems encoding genes of UE210113, Δpk1 and Δpk1-C were performed by using qRT-PCR analysis. By using two independent sample Mann-Whitney U test, the drug susceptibility results showed that, compared with UE210113 strain, the sensitivities of Δpk1 to ceftazidime, cefepime, tobramycin, minocycline and cotrimoxazole were enhanced (Z=-2.121,P<0.05;Z=-2.236,P<0.05;Z=-2.236,P<0.05;Z=-2.121,P<0.05), and the drug susceptibility of Δpk1-C restored to the same as which of UE210113 (Z=0,P>0.05). The expression levels of ESBLs-enconding genes blaTEM and blaCTX-M-14 in Δpk1 were significantly down-regulated compared with UE210113, but the expression was not restored in Δpk1-C. The expression of outer membrane protein gene omp F in Δpk1 was significantly up-regulated, while the expression of omp A and omp C were down-regulated. The results showed that the expression of multidrug efflux systems encoding genes tol C, mdt A and mdtG were down-regulated in Δpk1 compared with UE210113. The expression of all of the outer membrane protein genes and the multidrug efflux systems genes were restored in Δpk1-C. In conclusion,the lost of ppk1 gene can affect the expression of the outer membrane protein and multidrug efflux systems encoding genes of ESBLs-UPEC, which increase the sensitivity of ESBLs-UPEC to various drugs.

Genetic diversity analysis of Penicillium marneffei isolated from AIDS patients in Guangdong, China using randomly amplified polymorphic DNA / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Penicillium marneffei (P. marneffei) is an emerging pathogenic fungus that can cause invasive mycosis in patients with AIDS. The epidemiological features of P. marneffei infection in AIDS patients in Guangdong province remain unclear so far. This study aimed to investigate the genetic diversity within a population of 163 P. marneffei isolates obtained from AIDS patients and search for the dominant clinical strains in Guangdong province.</p><p><b>METHODS</b>One hundred and sixty-three P. marneffei isolates obtained from AIDS patients in Guangdong province during January 2004 and December 2009 were studied by randomly amplified polymorphic DNA (RAPD) using two random primers (H2 and H22). The degree of similarity between samples was calculated through similarity coefficients from RAPD fragment data and the dendrogram was assessed using the unweighted pair group method with arithmetic mean (UPGMA).</p><p><b>RESULTS</b>Two primers showed a high degree of discrimination and good stability. Primer H2 yielded eight different patterns (H2-1 to H2-8) among 163 isolates with the discriminatory power being 0.413. Primer H22 identified seven types (H22-1 to H22-7) among 163 isolates with the discriminatory power being 0.467. Genetic similarity coefficients based on RAPD data among 163 P. marneffei isolates ranged from 0.681 to 0.957, 61.96% of which were no less than 0.83. The discriminatory power of the two primers was 0.524. One hundred and sixty-three P. marneffei isolates were clustered into nine distinct groups (groups I to IX) at the similarity coefficient value of 0.83 and group I was the most common, including 101 strains (61.96%).</p><p><b>CONCLUSION</b>The RAPD analyses could provide important information as to the degree of genetic diversity and the relationship among clinical P. marneffei isolates, revealing genetic polymorphism and dominant strains.</p>

Analysis on clinical and epidemiological characteristics of 1032 patients with Dengue fever in Guangzhou / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the clinical and epidemiological characteristics of Dengue fever (DF) during the Dengue-1 epidemic in Guangzhou.</p><p><b>METHODS</b>Clinical and epidemiological data of 1032 patients with DF from May 2002 to November 2003 were retrospectively analyzed. Dengue virus were isolated by cell culture and typed by reverse transcriptase polymerase chain reaction (RT-PCR).</p><p><b>RESULTS</b>Age of the patients ranged from 55 days to 91 years old (average 34.7 +/- 13.2 years) with sex ratio 1.03:1. Incubation period ranged from 2 to 12 days with mean periods of 5.3 +/- 2.4 days. Most (45.0%) cases appeared in September and the epidemic last from July to November. Dengue outbreak had involved 675 cases in 26 common places. The common manifestations were seen as fever (100%), headache (90.9%), myalgia (68.4%), bone soreness (48.8%), fatigue (79.3%), skin rash (60.1%), positive tourniquet test (45.3%), leukopenia (63.3%) and thrombocytopenia (60.8%), respectively. Dengue virus was isolated from serum of 19 out of 54 patients' and identified as Dengue virus type 1. DNA sequence analyzes on rates of nucleotide homology were 97%, 97% and 98% compared with those of Dengue virus type 1 strain of DF outbreak in Cambodia, in 1997 and 1999 in China.</p><p><b>CONCLUSION</b>The epidemic of DF in Guangzhou in 2002/2003 was caused by Dengue virus type-1 with most patients showing classic type of the disease. Date suggested that change can happen from non-endemic to hypoendemic regions in Guangdong province.</p>