尿液中奇异变形杆菌耐药性变迁及监测分析

目的了解尿液中奇异变形杆菌临床分布及耐药性变迁情况,为临床医生合理选用抗生素提供理论依据。方法收集2008年至2012年住院及门诊患者尿液标本中分离的215株奇异变形杆菌,采用VITEK2 Compact全自动微生物分析仪进行鉴定及药敏试验,采用WH0NET 5.4软件进行统计分析。结果2008、2009、2010、2011和2012年分离奇异变形杆菌分别为26株（占12. 2% ）、26株（占12.2% ）、36株（占16. 9% ）、55株（占25. 8% ）和72株（占33. 8% ）,总计215株。奇异变形杆菌对呋喃妥因的耐药率最高,均〉90%,对丁胺卡那霉素和美洛培南的耐药率最低,均为0%,对左旋氧氟沙星的耐药率在2008？2011年均〉50% ,2012年为28.1% ;对哌拉西林/他唑巴坦的耐药率在2008 - 2009年均〉20%,而2010-2012年均〈5% ;头孢替坦、舒普深耐药率均〈7%。结论奇异变形杆菌的分离率从2008 -2012年呈日益增长趋势,提醒我们随着临床上大量使用抗生素,医院的感染率亦不断上升。耐药率从2008-2011年基本呈上升趋势,而在2012年有所下降,这可能与近几年本院临床严格执行抗菌药物的合理应用有关。     

Dynamics of drug resistance in Proteus mirabilis cultures 1970-1985

Resistance of 669 clinical strains of Proteus mirabilis to 18 chemotherapeutic drugs was studied in dynamics within 1970-1985. An increase in the number of cultures resistant to ampicillin and carbenicillin was noted while the number of cultures resistant to cephalosporines did not change. Within the period from 1970 to 1975 there was observed a marked increase in the number of Proteus strains resistant to aminoglycoside antibiotics. After that period their number gradually lowered and in 1985 reached the level of 1970. Beginning from 1973 there were observed a decrease in the number of Proteus chloramphenicol resistant strains and simultaneous occurrence of cultures sensitive to this antibiotic. The predominating number of the tested strains preserved during the whole observation period their resistance to tetracycline, doxycycline, rifampicin, novobiocin, furazolidone and furagin. No increase in the number of Proteus strains with multiple drug resistance including those resistant to 5-7 drugs was noted in the observation periods of 1970-1975, 1980 and 1985. The most frequent were Proteus strains resistant to 2-4 drugs. Among them cultures resistant to chloramphenicol and aminoglycoside antibiotics of the first generation predominated. Grouping of the strains by the same resistance spectra provided dividing the rested cultures of Proteus mirabilis into 69 variants.     

Alternate forms of the resistance factor R1 in Proteus mirabilis

The resistance factor R1 may exist in either of two stable physical states in Proteus mirabilis PM-1. In one case, the R1 deoxyribonucleic acid (DNA) has a buoyant density of 1.711 g/cm(3) and replicates under stringent control. Cells harboring R1 in this form may transfer drug resistance by conjugation. In the other case, R1 DNA shows two buoyant density classes at 1.707 and 1.714 g/cm(3). The 1.714 g/cm(3) component is replicated under a degree of relaxed control, and strains carrying this form generally cannot transfer drug resistance by conjugation. Intracellular amounts of the R factor-coded enzyme, chloramphenicol acetyltransferase, did not correspond to amounts of plasmid DNA in Proteus, and the enzyme was present in lower amounts than in Escherichia coli. It is proposed that the two states of R1 in Proteus may represent stable associated and dissociated forms of the plasmid.     

Specialized transduction of kanamycin resistance in a Providence strain.

Properties of a transducing system with a phage able to transduce a kanamycin-resistance marker of the T compatibility group plasmid R394 at a frequency of 2 times 10(-2)/plaque-forming unit adsorbed are described. The phage was detected in Providence strain P29 transduced to kanamycin resistance by Providence phage PL25 grown on this strain harbouring the R factor. Four P29 transductants, specially selected at the lowest multiplicities of infection of the high frequency transducing (HFT) phage, were defective lysogens. They plated PL25 with an efficiency of I and only one liberated low-titre phage spontaneously or on u.v. induction. The defect in maturation function could be corrected by introduction of a wild PL25 prophage. The transducing phage was serologically frequency was increased by the simultaneous presence of homologous non-transducing phage. Transductants did not transfer the kanamycin-resistance marker by conjugation, and produced kanamycin-sensitive segregants at a moderate rate. These segregants could be transduced to kanamycin resistance by the HFT phage. Irradiation of HFT lysates by u.v. produced an exponential fall in transduction frequency. It was concluded that the defective phage transduced by lysogenization. Kanamycin-resistant transductants could themselves be transduced by streptomycin resistance by PL25 reared on a streptomycin-resistant mutant. Lysogenic transductants produced by the HFT phage did not always liberate HFT phage on u.v. induction. Possible explantations are considered.     

Endonuclease from Proteus mirabilis

Two isoforms of nuclease displaying DNase and RNase activities were found in the culture liquid and periplasm of Proteus mirabilis. The enzyme was isolated from the periplasm and then purified to a functionally homogeneous state. The nuclease was equally potent in cleaving denatured and native DNAs by the endonuclease mechanism and was designated Pm endonuclease. The endonuclease was shown to be a temperature-dependent enzyme with a pH optimum of 10.4-10.6, requiring the presence of bivalent metal ions and inhibited by citrate and ethylenediaminetetraacetate.     

Endonuclease from Proteus mirabilis

Two isoforms of nuclease displaying DNase and RNase activities were found in the culture liquid and periplasm of Proteus mirabilis. The enzyme was isolated from the periplasm and then purified to a functionally homogeneous state. The nuclease was equally potent in cleaving denatured and native DNAs by the endonuclease mechanism and was designated Pm endonuclease. The endonuclease was shown to be a temperature-dependent enzyme with a pH optimum of 10.4–10.6, requiring the presence of bivalent metal ions and inhibited by citrate and ethylenediaminetetraacetate.     

Phosphatase from Proteus mirabilis

Cell-free preparations of Proteus mirabiliscontained a phosphatase (EC 3.1.3.1) whose activity surpassed that of alkaline phosphatase from Escherichia coli. Phosphatase was also found in the culture liquid of P. mirabilis. The composition of proteins displaying enzyme activity was assayed by polyacrylamide gel electrophoresis. Enzyme synthesis was studied at various stages of bacterial growth. Biosynthesis of phosphatase in P. mirabilis(similarly to that found in other bacteria) was shown to be induced under conditions of inorganic phosphate deficiency in the medium.     

Phosphatase from Proteus mirabilis

Cell-free preparations of Proteus mirabilis contained a phosphatase (EC 3.1.3.1), whose activity surpassed that of alkaline phosphatase from Escherichia coli. Phosphatase was also found in the culture liquid of P. mirabilis. The composition of proteins displaying enzyme activity was assayed by polyacrylamide gel electrophoresis. Enzyme synthesis was studied at various stages of bacterial growth. Biosynthesis of phosphatase in P. mirabilis (similarly to that in other bacteria) was shown to be induced under conditions of inorganic phosphate deficiency in the medium.     

Biosynthesis of Proteus mirabilis Nuclease

The culture liquid and periplasm of Proteus mirabilis contained nuclease, an enzyme with DNase and RNase activities. The nuclease was most actively synthesized in the early exponential and stationary growth phases. Nuclease synthesis was regulated by nucleic acids (induction by substrate) and inorganic phosphate (end-product inhibition). The synthesis and secretion of nuclease by P. mirabilis was induced by mitomycin C, an inducer of the SOS functions of cells. This suggests the involvement of SOS-response proteins in the regulation of nuclease synthesis.     

The phospholipases of Proteus mirabilis

The method of screening Proteus for phospholipase activity has been worked out. The study of isolated clones of the same strain, used as an example, has revealed that clones differing in their phospholipase activity also differ in virulence and in some parameters of interaction in the host-parasite system. P. mirabilis phospholipases are supposed to be of importance as one of the factors contributing to the invasive properties of these microorganisms at the stage of overcoming the epithelial cell barrier of mucous membranes.     

Fimbriae of uropathogenic Proteus mirabilis

Proteus mirabilis is a common causative agent of cystitis and pyelonephritis in patients with urinary catheters or structural abnormalities of the urinary tract. Several types of fimbriae, which are potentially involved in adhesion to the uroepithelium, can be expressed simultaneously by P. mirabilis: mannose-resistant/Proteus-like (MR/P) fimbriae, P. mirabilis fimbriae (PMF), uroepithelial cell adhesin (UCA), renamed by some authors nonagglutinating fimbriae (NAF), and ambient-temperature fimbriae (ATF). Proteus mirabilis is a common cause of biofilm formation on catheter material and MR/P fimbriae are involved in this process. The considerable serious pathology caused by P. mirabilis in the urinary tract warrants the development of a prophylactic vaccine, and several studies have pointed to MR/P fimbriae as a potential target for immunization. This article reviews P. mirabilis fimbriae with regard to their participation in uropathogenesis, biofilm formation and as vaccine targets.     

Sublethal ciprofloxacin treatment leads to resistance via antioxidant systems in Proteus mirabilis

This study investigates new aspects of the possible role of antioxidant defenses in the mechanisms of resistance to ciprofloxacin in Proteus mirabilis. Four ciprofloxacin-resistant variants (CRVs), selected in vitro by repeated cultures in a sub-minimum inhibitory concentration (MIC) concentration of ciprofloxacin, attained different levels of antibiotic resistance and high Ferric reducing antioxidant power, with 10(-6) frequencies. However, no mutations occurred in positions 83 or 87 of gyrA, 464 or 466 of gyrB, or 78, 80 or 84 of parC, suggesting that resistance took place without these typical mutations in DNA gyrase or topoisomerase IV. Assays with ciprofloxacin and the pump inhibitor carbonyl cyanide m-chlorophenylhydrazone showed that in addition to the antioxidant mechanisms, the influx/efflux mechanism also contributed to the increase in the resistance to ciprofloxacin in one CRV. Moreover, lipid oxidation to malondialdehyde and protein oxidation to carbonyls and advanced oxidation protein products were higher in sensitive than in the resistant strains, as a new factor involved in the mechanisms of resistance in P. mirabilis. The oxidative stress cross-resistance to telluride in CRVs enhanced the role of the antioxidants in the ciprofloxacin resistance of P. mirabilis, which was reinforced during the assays of reduction of susceptibility to ciprofloxacin by glutathione and ascorbic acid.