Analysis of antibiotic resistance and virulence patterns in Klebsiella pneumoniae isolated from human urinary tract infections in India

In this study, 504 urine samples collected from patients suffering from urinary tract infection (UTIs) were screened for the presence of Klebsiella pneumoniae. The overall occurrence of Klebsiella spp. and K. pneumoniae was found to be 23·2% (117/504) and 16·8% (85/504) respectively. Antibiotic susceptibility testing of 85 K. pneumoniae isolates was carried out by disc diffusion which revealed alarming levels of antibiotic resistance (ABR). Antimicrobial resistance was prominently observed against cefpodoxime (76·47%) followed by ampicillin (70·59%), ceftriaxone (52·94%), cefoxitin (50·59%), amoxyclav (48·24%), ofloxacin (45·88%), cefotaxime (44·71%), cefepime (43·53%) and doxycycline hydrochloride (40%). A small percentage of strains also exhibited resistance to other antimicrobials in the range of 7–35%. Around 77·6% of the isolates were found to be resistant to three or more antibiotic classes and 66·7% of the isolates had multiple antibiotic resistance index values >0·2. Screening of virulence genes in 85 K. pneumoniae isolates revealed that uge gene was the most predominant (11/85, 12·9%), followed by rmpA (9/85, 10·5%), kfu (4/85, 4·7%) and aerobactin genes (2/85, 2·35%). Further, the overall percentage of biofilm producers were found to be 17·65% (15/85). This study warrants hospitals and health care centres to reduce misuse of antibiotics and manage UTI with appropriate treatment after performing antibiotic susceptibility testing.     

仙居县儿童下呼吸道感染肺炎克雷伯菌耐药性分析

目的分析仙居人民医院住院下呼吸道感染患儿临床分离肺炎克雷伯菌的耐药特征,为临床合理用药提供依据。方法选择2012年7月至2013年7月该院下呼吸道感染肺炎克雷伯菌阳性患儿81例。对患儿的临床一般资料进行分析,对临床分离菌株进行细菌鉴定,用18种抗生素进行药敏试验,采用WHONET5．4分析软件进行统计。结果2012年7月至2013年7月共分离出81株肺炎克雷伯菌,ESBLs阳性42株,检出率为51．85％。所有菌株对亚胺培南、厄他培南、左旋氧氟沙星、丁胺卡那100％敏感。对氨苄西林耐药率为100％。ESBLs阴性菌株对氨曲南、头孢曲松、头孢他啶、头孢唑啉、头孢吡肟100％敏感,而ESBLs阳性菌株则100％耐药。ESBLs阴性菌株对其他抗生素的耐药率为氨苄西彬舒巴坦（12．82％）、环丙沙星（2．56％）、头孢替坦（O％）、呋喃妥因（20．51％）、庆大霉素（5．13％）、复方新诺明（17．85％）、妥布霉素（2．56％）、哌拉西林／他唑巴坦（2．56％）;ESBLs阳性菌株对其他抗生素的耐药率为氨苄西林／舒巴坦（73．80％）、环丙沙星（2．38％）、头孢替坦（16．67％）、呋喃妥因（61．90％）、庆大霉素（28．57％）、复方新诺明（54．76％）、妥布霉素（7．14％）、哌拉西林／他唑巴坦（7．14％）。结论本地区患儿中肺炎克雷伯菌耐药性较高,临床应重视病原菌的检测。     

Characteristics ofPseudomonas aeruginosa strains isolated from urinary tract infections

Thirty-three uropathogenic strains ofPseudomonas aeruginosa were investigated for hemolytic activity in both bacterial broth culture filtrates and isolate lyzates, resistance to bactericidal activity of fresh human serum, resistance to six antibiotics and plasmid DNA profile. Twenty-four of the 33 (73%) bacterial filtrates showed lysis of rabbit erythrocytes, as did the three after guinea-pig erythrocyte treatment. Twelve of 33 isolate lysates showed in parallel lysis of both types of erythrocytes used. Serum resistance was found in 17 (52%) isolates, intermediate resistance in 15 (45%) isolates and only one isolate showed serum sensitivity. Resistance to antibiotics was detected as follows (in %): tetracycline 94, kanamycin 79, chloramphenicol 76, septrin 73, ampicillin 64, streptomycin 45, gentamicin 18. None of the isolates investigated showed resistance to colistine. With the exception of one isolate, plasmid DNA was detected in allP. aeruginosa strains.     

Antibiotic susceptibility and genotype patterns of Escherichia coli, Klebsiella pneumoniae and Pseudomonas aeruginosa isolated from urinary tract infected patients

Thirty nine isolates of Escherichia coli, twenty two isolates of Klebsiella pneumoniae and sixteen isolates of Pseudomonas aeruginosa isolated from urinary tract infected patients were analyzed by antimicrobial susceptibility typing and random amplified polymorphic DNA (RAPD)-PCR. Antibiotic susceptibility testing was carried out by microdilution and E Test methods. From the antibiotic susceptibility, ten patterns were recorded (four for E. coli, three for K. pneumoniae and three for P. aeruginosa respectively). Furthermore, genotyping showed seventeen RAPD patterns (seven for E. coli, five for K. pneumoniae and five for P. aeruginosa respectively). In this study, differentiation of strains of E. coli, K. pneumoniae and P. aeruginosa from nosocomial infection was possible with the use of RAPD.     

The Yersinia high-pathogenicity island in Escherichia coli and Klebsiella pneumoniae isolated from polymicrobial infections

We examined 12 pairs of strains of Escherichia coli and Klebsiella pneumoniae isolated from mixed infections in human for the presence of the Yersinia high-pathogenicity island (HPI). In one case both isolates carried the HPI, whereas in 11 cases one strain of the pair was HPI-positive. Although there were differences in the organization of the Yersinia HPI, all HPI-positive isolates were able to produce yersiniabactin. The presence of the Yersinia HPI may enhance the capability of strains involved in mixed infections to replicate in iron-deprived conditions in the host.     

Drug resistance and proticinogenic types of Proteus mirabilis isolated from urinary tract infections

Proteus mirabilis strains (88 isolates) from hospitalised patients with urinary tract infection were tested for antibiotic susceptibility, ESBL production and their ability to produce proticin or on their susceptibility to proticin. Antibiotic susceptibility test was performed by standard disc diffusion method according to NCCLS. Proticin typing was made by the standard strain set from the B. W. Senior collection. Most (59%) strains belonged to ESBL producers and were more resistant to antibiotics than ESBL-negative strains. Predominant proticin patterns among the ESBL (+) strains were: P1,2(6)/SO (23%), P1,2/SO (13.5%). Among the ESBL-negative strains more frequent were P6/SO (16.6%), P1,2/SO (13.8%) and P3,6/SO (13.8%) proticin types.     

Susceptibility of chemostat-grown Yersinia enterocolitica and Klebsiella pneumoniae to chlorine dioxide

The resistance of bacteria to antimicrobial agents could be influenced by growth environment. The susceptibility of two enteric bacteria, Yersinia enterocolitica and Klebsiella pneumoniae, to chlorine dioxide was investigated. These organisms were grown in a defined medium in a chemostat and the influence of growth rate, temperature, and cell density on the susceptibility was studied. All inactivation experiments were conducted with a dose of 0.25 mg of chlorine dioxide per liter in phosphate-buffered saline at pH 7.0 and 23 degrees C. The results indicated that populations grown under conditions that more closely approximate natural aquatic environments, e.g., low temperatures and growth at submaximal rates caused by nutrient limitation, were most resistant. The conclusion from this study is that antecedent growth conditions have a profound effect on the susceptibility of bacteria to disinfectants, and it is more appropriate to use the chemostat-grown bacteria as test organisms to evaluate the efficacy of a certain disinfectant.     

Susceptibility of chemostat-grown Yersinia enterocolitica and Klebsiella pneumoniae to chlorine dioxide.

The resistance of bacteria to antimicrobial agents could be influenced by growth environment. The susceptibility of two enteric bacteria, Yersinia enterocolitica and Klebsiella pneumoniae, to chlorine dioxide was investigated. These organisms were grown in a defined medium in a chemostat and the influence of growth rate, temperature, and cell density on the susceptibility was studied. All inactivation experiments were conducted with a dose of 0.25 mg of chlorine dioxide per liter in phosphate-buffered saline at pH 7.0 and 23 degrees C. The results indicated that populations grown under conditions that more closely approximate natural aquatic environments, e.g., low temperatures and growth at submaximal rates caused by nutrient limitation, were most resistant. The conclusion from this study is that antecedent growth conditions have a profound effect on the susceptibility of bacteria to disinfectants, and it is more appropriate to use the chemostat-grown bacteria as test organisms to evaluate the efficacy of a certain disinfectant.     

2014—2016年大连地区血流感染肺炎克雷伯菌的耐药性特征分析

目的 分析肺炎克雷伯菌所致血流感染患者的科室分布及其病原菌耐药性特征,为指导临床合理应用抗菌药物,有效控制感染提供依据。方法 选择2014—2016年大连医科大学附属第一医院送检血液标本中分离得到的289株肺炎克雷伯菌,对其进行细菌鉴定、药敏试验及ESBL确认试验,分析肺炎克雷伯菌所致血流感染的科室分布特征及其病原菌耐药性变迁。结果 患者血液中肺炎克雷伯菌检出率以急诊科（24.91%）和ICU为最高（23.88%）。3年中肺炎克雷伯菌对碳青霉烯类抗生素和阿米卡星耐药率较低,均在20.00%左右。产ESBL肺炎克雷伯菌共135株,占46.71%,对常用抗生素的耐药率均显著高于非产ESBL菌株（P<0.01）。碳青霉烯类抗生素耐药菌株对常用抗生素耐药率均高于敏感菌株（P<0.01）,对四环素、复方新诺明和阿米卡星耐药率相对较低,分别为66.10%、66.10%、71.19%。结论 我院2014—2016年患者血液中肺炎克雷伯菌检出率以急诊科和ICU为最高。该菌对碳青霉烯类抗生素及阿米卡星的耐药率较低,碳青霉烯类抗生素耐药菌株对四环素、复方新诺明和阿米卡星尚有一定敏感性。     

Biotyping and resistotyping for epidemiological tracing of the fecal origin of Klebsiella pneumoniae in urinary infections

Twenty-four (82.7%) out of 29 patients suffering from hospital acquired urinary infections by Klebsiella pneumoniae had the same species in their faeces. Biotyping of 24 urinary and 219 fecal strains of K. pneumoniae resulted in 50 different biotypes - an average of four biotypes per fecal sample. Ten patients (34.4%) had the same biotype in urine and faeces without any correlation with previous vesical catheterization (p greater than 0.05). Using resistotyping to four chemical compounds selected among 34 tested substances (brilliant green, malachite green, potassium tellurite and mercuric chloride) 16 different resistotypes were found. Fourteen patients (58.3%) presented the same resistotype in urine and faeces but only in five patients was there correlation with simultaneous biotyping identity. Simultaneous occurrence of identical biotypes or resistotypes in faeces and urine occurred in only 54.2% of cases. However, there was a significant association between resistance ot mercuric and tellurite ions in fecal and urinary strains isolated from the same patient (p less than 0.001).     

Purification and chemical characterization of type 1 pili isolated from Klebsiella pneumoniae

Type 1 pili were purified from a Klebsiella pneumoniae strain isolated from a human urinary tract infection. The pili were removed from the bacteria by mechanical shearing, precipitated out of solution by ammonium sulfate, solubilized in a deoxycholate-containing buffer, and finally purified by gel filtration. Chemical characterization of the isolated pili revealed a single protein subunit (pilin) which had a Mr = 21,500. Amino acid compositional analysis revealed a high content of residues that contribute significantly to secondary structure. Automated sequence analysis of the NH2-terminal region revealed a striking homology (79% identity) with type 1 pili of Escherichia coli. In contrast, NH2-terminal sequence comparison of K. pneumoniae pilin with other previously reported bacterial pilins showed no significant homology. No immunological cross-reactivity was detectable between E. coli and K. pneumoniae pili when tested by Ouchterlony double immunodiffusion or by rocket immunoelectrophoresis. The results of this study, when compared to other studies of bacterial pili, indicate that type 1 pili from members of the Enterobacteriaceae share morphological similarities and that their monomeric subunits are chemically similar. In addition, these results give strong evidence that the type 1 pilins of the enteric bacteria represent a separate class of homologous pilins.     

Starvation and nutrient resuscitation of Klebsiella pneumoniae isolated from oil well waters

Klebsiella pneumoniae isolated from oil well waters reduced in size in response to nutrient starvation. The cells remained viable during starvation and later were able to grow rapidly when stimulated by nutrients. The heterotrophic potential, culture absorbance and extracellular polysaccharide production decreased during cell starvation whereas an initial increase in colony-forming units was observed on agar plates. Transmission electron microscopy (TEM) after 24 d revealed that the cells had changed to small rods or cocci between 0.5 by 0.25 micron and 0.87 by 0.55 micron. When transferred to half-strength brain heart infusion medium, TEM showed cell division and rod-shaped cells after 45 min and full resuscitation within 4 h. Cell response was much slower in sodium citrate medium and resuscitation took 8 h.     

Starvation and nutrient resuscitation of Klebsiella pneumoniae isolated from oil well waters

Klebsiella pneumoniae isolated from oil well waters reduced in size in response to nutrient starvation. The cells remained viable during starvation and later were able to grow rapidly when stimulated by nutrients. The heterotrophic potential, culture absorbance and extracellular polysaccharide production decreased during cell starvation whereas an initial increase in colony-forming units was observed on agar plates. Transmission electron microscopy (TEM) after 24 d revealed that the cells had changed to small rods or cocci between 0.5 by 0.25 μm and 0.87 by 0.55 μm. When transferred to half-strength brain heart infusion medium, TEM showed cell division and rod-shaped cells after 45 min and full resuscitation within 4 h. Cell response was much slower in sodium citrate medium and resuscitation took 8 h.