Antibiotics sensitivity of "hospital" strains of S. typhimurium]

Sensitivity of Styphimurium strains isolated under conditions of a hospital infection to antibiotics were studied in comparison with the strains of the given serological type isolated from other sources and with the strains of other serological types of groups B, C, D and E. It was shown that the strains causing outbreaks of hospital infections were characterized by polyresistance to 7 out of 9 antibiotics tested. All the Salmonella strains tested were sensitive to gentamicin and about a half of them was sensitive to polymyxin M.     

Antibiotic Resistant Group A Streptococci

A series of Streptococcus pyogenes strains, including strains isolated from patients, mutants which had acquired in vitro resistance to penicillin (Pc), mitomycin C (MC), tetracycline (TC) and chloramphenicol (CM), ultraviolet light induced α hemolytic mutants, as well as β hemolytic mutants (β mutants) derived from α hemolytic mutants (α mutants) were compared as to their antibiotic sensitivity, and physiological, biochemical and serological properties. To obtain β mutants from α mutants the following procedures were employed: (1) serial mouse passage, (2) serial serum-broth transfers, (3) cultivation in heat-killed cultures of parent strains, and (4) cultivation in broth containing bacterial DNA extracted from parent streptococcus cells. From the results obtained these strains could be divided into two major groups, each with two subgroups. Group 1 strains produce soluble hemolysins and are sensitive to Pc. Subgroup 1–1 strains are sensitive to other antibiotics too; subgroup 1–2 are resistant to certain antibiotics other than Pc, bacitracin and MC. Group 2 strains do not produce soluble hemolysins and resistant to Pc. Subgroup 2-1 strains are α hemolytic on horse blood agar and subgroup 2–2 are β hemolytic on the same medium. Pc resistance in group 2 strains was more than 100-fold higher than that of sensitive strains, and was accompanied by MC resistance, but to a lesser degree. Pc resistance in group 2 mutants could be induced by antibiotics other than Pc and also by ultraviolet irradiation. Although group 1 cells retained the characteristics of typical S. pyogenes, group 2 cells, both α and β hemolytic, lost most of the physiological, biochemical and serological properties of this species. The similarity of group 2 strains to group D or group N streptococcal strains in their general properties is discussed.     

Serratia marcescens: Biochemical, Serological, and Epidemiological Characteristics and Antibiotic Susceptibility of Strains Isolated at Boston City Hospital

The biochemical, serological, and epidemiological characteristics of 95 strains of Serratia marcescens isolated at the Boston City Hospital were examined. Several strains were shown to be endemic, and the majority of isolates were cultured from urine or respiratory secretions. Serratia species were highly resistant to polymyxin B and the cephalosporins, and various proportions were also resistant to other antibiotics including kanamycin, but all of the isolates were sensitive to gentamicin. The appearance of resistance to kanamycin and nalidixic acid among endemic strains was demonstrated. The nosocomial nature of Serratia infections, particularly those involving the urinary tract, was confirmed. Many clinical bacteriology laboratories currently fail to identify the nonpigmented strains.     

Phagocytosis of chloramine B sensitive and resistant staphylococci isolated from healthy persons and patients

Phagocytic reaction with respect to antibiotic and chloramine B sensitive and resistant staphylococci isolated from healthy persons and patients, air and stock of medical institutions was studied on albino mice. It was shown that the staphylococcal isolates included strains simultaneously sensitive to antibiotics and chloramine, sensitive to antibiotics and resistant to chloramine, resistant to antibiotics and sensitive to chloramine and simultaneously resistant to antibiotics and chloramine. Activity, intensity and completeness of phagocytosis by leucocytes from mouse abdominal cavity exudates with respect to the staphylococcal strains sensitive to antibiotics and resistant to chloramine, resistant to antibiotics and sensitive to chloramine and simultaneously resistant to antibiotics and chloramine were lower than the values of the phagocytic reaction with respect to the isolates simultaneously sensitive to antibiotics and chloramine. This suggested that not only antibiotic resistance of microbes but also their resistance to disinfectants could be referred to complicating factors of hospital infections.     

Sensitivity of 56 strains of Streptococcus group B to 12 antibiotics: its determination by dilution and diffusion in agar

Sensitivity of 56 streptococcal strains of group B to 12 antibiotics was studied with the method of dilution in a special solid medium for cultivation of streptococci and with the method of agar diffusion in the same medium. All the strains were found to be sensitive to chloramphenicol, ristomycin and erythromycin. The predominating majority of the strains were sensitive to beta-lactam antibiotics and lincomycin. All the strains were resistant to aminoglycoside antibiotics, such as streptomycin and gentamicin. More than 85 per cent of the strains were resistant to tetracycline. Strains with multiple resistance to 2-7 antibiotics were detected. Satisfactory correlation between the two methods was observed. It was shown to be clinically advisable to determine the sensitivity of streptococci of group B to beta-lactam antibiotics, erythromycin and lincomycin.     

Antibiotic resistance of Lactobacillus strains]

One hundred and thirty six Lactobacillus strains isolated from poultry and 23 Lactobacillus strains isolated from long-living persons were tested for their antibiotic sensitivity. Occurrence of some type determinants of resistance to aminoglycoside antibiotics and tetracyclines in the Lactobacillus strains resistant to these antibiotics was studied. The majority of the strains from the both collections were resistant to aminoglycosides (73 and 79 per cent, respectively). The isolates from the poultry were characterized by multiple resistance. The isolates from the long-living persons were most frequently resistant to one of two antibiotics. All the tested Lactobacillus strains isolated from the long-living persons were sensitive to tetracyclines. The species composition of the isolates was different. The antibiotic-resistant strains were detected in all the species involved in the study. By hybridization of Lactobacillus colonies with the probes containing various genes of the resistance it was shown that in 14 per cent of the antibiotic-resistant strains belonging to Lactobacillus the antibiotic resistance was controlled by the genes homologous to resistance genes widely distributed in gramnegative organisms. This indicated a possible wide exchange and heterologous expression of the antibiotic resistance determinants between microorganisms of various taxonomic groups.     

Antibiotic sensitivity of Vibrio cholerae 01 isolated from environmental objects]

The sensitivity of 252 Vibrio cholerae-O1 strains isolated from environmental objects to antibiotics of various groups was assayed by the method of serial dilutions on solid media. The biological characteristics of the isolates are presented. The Vibrio cholerae isolates with serological variation were the most frequent (36.6 per cent), so are the cultures detected by their sensitivity to the specific phages (87.5 per cent). It was found that changes in some biological properties of the strains did not coincide with the changes in the antibiotic sensitivity. The isolates were highly sensitive to tetracycline, chloramphenicol, gentamicin, erythromycin and rifampicin and less sensitive to novobiocin and the other aminoglycosides. The sensitivity to the beta-lactams was the lowest. The resistance determinants were detected in single strains (6.3 per cent), the kanamycin and novobiocin resistance determinants being detected in 15 out of the 16 strains tested. The study showed that the cultures of Vibrio cholerae-O1 isolated from the environmental objects generally preserved their sensitivity to the diverse group antibiotics.     

Resistance of different strains of pathogenic staphylococcus to unfavorable environmental factors]

A study was made of the resistance to drying the UV-irradiation, the action of furacillin and chloramine displayed by 60 stains of S. aureus differing by origin (hospital and extrahospital), by the source of discharge (the upper respiratory tracts of carriers and the discharge of the purulent-inflammatory foci of surgical patients), relation to the antibiotics (polyresistant and sensitive) and phage-group reference. It was found that the resistance of staphylococci to the unfavourable factors was not always associated with the listed signs of the strains. In respect to drying a marked resistance was expressed by the hospital strains in comparison with the extrahospital ones, polyresistant in comparison with the sensitive ones, staphylococci of III and I+III phage groups in comparison with the strains of other bacteriophage groups. Strains of the III phage group proved to be the most resistant to the UV-irradiation. Strains isolated from carriers were more resistant to furacillin than staphylococci isolated from the purulent-inflammatory foci. Strains of the III phage group and nontyping had analogous advantages over the cultures of other phage groups.     

Sensitivity of antibiotic-resistant strains of Salmonella to new antibiotics and chemotherapeutic agents]

One hundred and sixty two antibiotic resistant strains of Salmonella isolated within 1984-1988 in Leningrad and the Leningrad Region were tested with respect to their sensitivity to new antibiotics and chemotherapeutics developed or being developed in the USSR. At the background of high numbers of circulating Salmonella strains resistant to the routinely used antibiotics such as doxycycline, streptomycin and gentamicin they appeared to be highly sensitive to amikacin, ciprofloxacin, pefloxacin and the 3rd generation cephalosporins i.e. ceftazidime and cefotaxime as well as to thienamycin. These modern antibacterial agents are possibly to be the drugs of choice in etiotropic treatment and chemoprophylaxis of septic acute intestinal infections due to Salmonella strains with multiple resistance. Resistance of individual Salmonella strains to cefotaxime and ceftazidime indicated that it was possible to use their property for additional labeling of the pathogens within a serological type of Salmonella while conducting epidemiological examinations during outbreaks of acute intestinal infections of Salmonella etiology.     

139株空肠弯曲菌耐药性分析

空肠弯曲菌(Campylobacter jejuni)是最常见的食源性病原菌之一。本研究采用微量肉汤稀释法对分离得到的139株空肠弯曲菌(117株为禽源样本分离株,22株为人源样本分离株)进行耐药性检测。通过对最小抑菌浓度(MIC)的判定结果得出:120株(86. 33%)空肠弯曲菌分离株对6类9组临床常用的抗生素表现出不同程度的耐药,其中禽源空肠弯曲菌耐药率为83. 76%,22株人源空肠弯曲菌均表现出耐药性。对喹诺酮类抗生素表现出高度耐药(环丙沙星80. 58%,萘啶酸77. 70%);对四环素类表现为中等耐药(四环素53. 24%);对部分大环内酯类、氨基糖苷类、林可酰胺类表现为低耐药(庆大霉素7. 19%,阿奇霉素5. 76%,克林霉素6. 47%);对酰胺醇类、部分大环内酯类表现为敏感(氟苯尼考0%,红霉素0%、泰利霉素0%)。139株空肠弯曲菌共产生14种耐药谱型,以TET-CIP-NAL谱型最多,占比38. 13%,耐三重及以上抗生素的多重耐药菌株占比53. 24%。禽源菌株中多重耐药占比46. 15%,人源菌株中多重耐药占比90. 91%。研究结果显示空肠弯曲菌耐药现状不容乐观,尤其对喹诺酮类与四环素类抗生素耐药性较为突出,且过半数菌株为多重耐药。本研究为食源性空肠弯曲菌的防控及临床用药提供参考。     

Correlation of Bacterial Lipid Composition with Antibiotic Resistance

The correlation of bacterial lipid composition with antibiotic resistance was investigated with particular emphasis on those organisms in which resistance may be related to membrane or envelope structure or function, as in resistance to tetracyclines and polymyxin. Chloroform-methanol-extractable lipids, phosphatidyl ethanolamine fractions, and both fatty acids of these lipid fractions and total fatty acids were studied by using thin-layer chromatography, gas chromatography, and infrared spectroscopy. Consistent quantitative differences were found between the fatty acid compositions of sensitive and resistant strains. Most notable was the fact that, in gram-negative organisms, resistant strains showed decreases in cyclopropane acids as compared with sensitive strains. These changes were found to be inherent in the strains and not due to growth stage or culture age. No significant qualitative differences were noted. In contrast, no such variation in fatty acid content was observed in penicillin-sensitive and resistant strains of gram-positive cocci. As significant alterations of fatty acid composition were noted in gram-negative strains resistant to antibiotics, we suggest that resistance is correlated to membrane or envelope lipid composition.     

The epidemic spread of Salmonella typhimurium phage type 10 in Canada (1970-1979)

The frequency of Salmonella typhimurium phage type 10 across Canada was monitored during the period 1970-1979. Phage type 10 isolations increased from 1.2% in 1970 to 68.8% in 1979 among isolates from human sources and from 1.5 to 30.6% in isolates from nonhuman sources. Examination of food-poisoning outbreaks and a study of the animal-host associations of phage type 10 revealed that contaminated poultry products appear to be the most common sources of human infections. The majority (89.3%) of S. typhimurium phage type 10 strains were sensitive to antibiotics. Of the resistant strains, 73.3% were resistant to single antibiotics and 26.7% were multiresistant. Thirty-three different patterns of antibiotic resistance were observed. A number of the resistance determinants were transferable by conjugation and the R plasmids were found to belong to the incompatibility groups HI1, FII, N, I alpha, and C.     

The antibacterial resistance of the strains making up the components of probiotic preparations

The spectrum of the antibiotic resistance of 21 strains of normal microflora, mainly forming constituents of widely used probiotics to 25 antibacterial preparations. Lactobacillus spp. were prevalent in the strains under test. The spectrum of the antibiotic resistance of lactobacilli varied, the gradation of resistance being more pronounced with respect to strains and not species. Both highly sensitive and highly resistant Lactobacillus strains were found: L. acidophilus (a component of biopreparation "Linex"), L. plantarum 8RA3, L. fermentum 90T4C (probiotic "Lactobacterin"), L. fermentum BL96. Bacteria used as the components of combined preparation "Linex" exhibited the highest resistance to a number of modern antibiotics. Strains of bifidobacteria were found to be highly sensitive to antibiotics.     

253株金黄色葡萄球菌耐药现状分析

目的 了解医院金黄色葡萄球菌临床分布情况及其对常用抗菌药物的耐药率,为临床合理使用抗菌药物提供依据.方法 回顾分析医院2010年5月至2011年4月检出的金黄色葡萄球菌,采用VITEK-AMS全自动微生物分析仪进行菌种鉴定和药敏分析.结果 共检出金黄色葡萄球菌253株,菌株的主要来源为痰130株(51.4％)、血液39株(15.4％)、创面24株(9.5％);菌株主要科室分布前3位是神内科35株(13.8％)、ICU30( 11.8％)、脑外科26株(10.3％);其中耐甲氧西林金黄色葡萄球菌( MRSA)为165株(65.2％),MRSA对多种抗菌药物耐药率＞70.0％,MSSA为88株(34.8％),对除青霉素、红霉素外的大多数抗菌药物敏感,未发现耐万古霉素菌株.结论 MRSA检出率高,耐药现状严重,应加强对金黄色葡萄球菌耐药性的监测,并根据药敏试验结果合理使用抗菌药物.     

Fecal coliforms of wastewater treatment plants: antibiotic resistance, survival on surfaces and inhibition by sodium chloride and ascorbic acid.

Three hundred and sixteen fecal coliform strains isolated from raw sewage and final effluents of two representative wastewater treatment plants were examined for antibiotic resistance. For plant A (which was disinfecting its effluents before discharge), 55% and 41% of the strains isolated from the influent and the effluent, respectively were resistant to one or more antibiotics. For plant B (which was not disinfecting its effluents before discharge), 33% and 58% of the strains isolated from the influent and the effluent, respectively were resistant to one or more antibiotics. A considerable proportion of these bacteria were resistant to three or more antibiotics. NaCl (3%) and ascorbic acid (0.1%) reduced the growth rate of both sensitive and resistant strains, and more inhibitory effects on the sensitive strains than on the resistant strains were observed. All resistant strains tested survived on various types of surfaces (e.g. glass, stainless steel, agar, cabbage, parsley and sand) significantly better than sensitive strains.     

R plasmid distribution in S. typhi isolated on the territory of the left coast of the Ukraine in 1970-1982

A total of 373 strains of S. typhi isolated in 1970-1982 were tested with respect to their sensitivity to 9 antibiotics active against gram-negative bacteria. It was shown that about 1/3 of the isolates were resistant to 1-3 antibiotics. Among the resistant isolates the number of strains resistant to 4-5 and more antibiotics amounted to 12.5 per cent. The plasmid nature of the antibiotic resistance in the isolated strains of S. typhi was shown. Transmissive R plasmids were detected in 13 per cent of the strains studied. Within the last 5 years there was an increase in the proportion of strains with transmissive R plasmids in patients with sporadic typhoid fever or especially in groups of patients with the disease.     

Infectivity and resistance to antibiotics of bacterial strains isolated from patients hospitalised in intensive care units

The aim of this study was to evaluate the frequency of isolation and antimicrobial resistance testing of bacterial strains isolated from clinical specimens from patients hospitalized in three Intensive Care Units in Wroc?aw. The susceptibility of bacteria (107 strains) to selected antibiotics was determined. The results clearly show that non-fermentative rods were identified as the main agents causing pneumonia (58% of isolates). The second commonest pathogens were Gram-positive cocci (29%). The P. aeruginosa and E. cloacae strains were resistant to ampicillin, amoxicillin/clavulanate, cefuroxime and cefotaxime. All isolates of A. baumanii were susceptible only to imipenem. The rods of K. pneumoniae and E. coli were resistant to ampicillin, about 55% strains of both bacteria were sensitive to other antibiotics, except piperacillin/tazobactam, imipenem and ciprofloxacin. About 90% of methicillin resistant S. epidermidis strains were resistant to all antibiotics, except vancomycin (100% isolates were sensitive). ESBL were detected among E. cloace, K. pneumoniae and E. coli. We found P. aeruginosa rods producing MBL.     

Sensitivity and resistance of a blue-green alga Phormidium mucicola to streptomycin and penicillin

Summary The alga Phormidium mucicola was found quite sensitive to antibiotics. Several strains resistant to streptomycin and penicillin were isolated following single and several contacts of antibiotics respectively. The resistant character remained stable during subcultures in drug-free medium. However, to isolate a fully stable and resistant strain of a concentration of penicillin two additional exposures to the same dose were required, unless otherwise, resistance was gradually lost during subcultures in penicillin-free media. This observation has been attributed to the heterogeneous nature of the resistant clones. Neither streptomycin nor penicillin resistant strains revealed cross-resistance to ultraviolet (u.v.) or to themselves.     

Resistance to antibacterial drugs of Enterobacteriaceae isolated from healthy children and from those with Salmonella infections

A total of 2329 Enterobacteriaceae strains in bacterial associations isolated from healthy children and children with salmonellosis were tested for their resistance to antimicrobial drugs. It was shown that the aerobic microbial associations isolated from the healthy children contained higher numbers of strains sensitive or resistant to 1-3 antibiotics while the microbial associations from the children patients with salmonellosis treated with antibiotics contained higher numbers of strains resistant to 6-8 antibiotics. Resistance of the aerobic bacterial associations was mainly defined by resistance of E. coli and K. pneumoniae. The feces of the healthy children never treated with antimicrobial drugs contained strains resistant to them. The use of the antibiotics in the treatment led to increasing numbers of the resistant bacteria and changing species composition of the bacterial associations.     

猪源大肠杆菌耐药质粒图谱及耐药性分析

目的:探讨猪大肠杆菌的耐药质粒图谱、耐药性及耐药基因之间的关系。方法:从湖南省株洲、益阳的四个猪场分离出9株大肠杆菌,进行质粒电泳图谱分析、用PCR法检测耐喹诺酮类耐药基因Gyr A、Par C和耐四环素类耐药基因Tet A、Tet B,并采用Kirby-bauer法对这9株大肠杆菌进行药敏(18种抗生素)试验。结果:其中9株大肠杆菌含有三条或者三条以上的质粒条带,且其质粒谱型均不相同;9株大肠杆菌均检测出4种耐药基因Gyr A、Par C、Tet A和Tet B;9株大肠杆菌对所选用的抗生素存在不同程度的耐药性,其中7株大肠杆菌对10种或10种以上的抗生素耐药,最高对13种抗生素耐药,氨苄西林、青霉素、阿莫西林、红霉素的耐药率达100%,对四环素、多西环素的耐药率达到88.9%,而多粘菌素B、阿奇霉素、大观霉素耐药率较低。结论:耐药性与质粒条带数、耐药基因之间并无明显的相关性;猪大肠杆菌呈多重耐药之势,在治疗大肠杆菌病时最好根据药敏实验结果选用合适的抗生素。