Sensitivity of bacteria of the genus Acinetobacter to antibiotics and ofloxacin

Between 1989-1989 276 strains of Acinetobacter genus were isolated which contained: Acinetobacter calcoaceticus subsp. anitratus (n = 167), Acinetobacter calcoaceticus subsp. Iwoffi (n- = 83), Acinetobacter haemolyticus (n = 26). Their sensitivity to aminoglycoside antibiotics, beta-lactams, tetracyclines, chloramphenicol, colistin, and ofloxacin was tested. More than 90% of strains were sensitive to colistin and ofloxacin. The sensitivity to remaining antibiotics differentiated depending on species. Acinetobacter anitratus were highly resistant to Ist and IInd generation of cephalosporins, and moreover to penicillins, tetracyclines, and chloramphenicol. Cephalosporins of IIIrd generation were active against 70% of strains with exception of cefoperazone what was also the case for representatives of aminoglycosides as netilmicin and amikacin. Strains of Acinetobacter Iwoffi were in majority sensitive to all antibiotics with exception of cephalothin, cephradine and cefoperazone. More than 90% of Acinetobacter haemolyticus strains were sensitive to gentamicin, carbenicillin, azlocillin, ceftriaxone, cefotaxime and tetracyclines.     

Antibiotic resistance of Pseudomonas aeruginosa strains isolated from patients with infected burns

Sensitivity to 15 drugs of 248 P. aeruginosa strains isolated from patients with infected burns was studied by the method of agar dilution. All of the strains were resistant to polymyxin M, ceporin, erythromycin and oleandomycin. Most of the strains were resistant to streptomycin, monomycin, ampicillin and rifadin. Moderate resistance of the strains to carbenicillin, morphocycline, vibramycin, kanamycin, tetraolean and tetracycline was observed: the maximum concentrations of these antibiotics (128 microgram/ml) inhibited the growth of 85, 69, 63, 51.8, 43.6 and 41.2 per cent of the strains respectively. Gentamicin proved to be most active against the strains of P. aeruginosa and inhibited 87 per cent of the strains when used in the therapeutic doses. The study provided recomendation of the drugs for parenteral and local use in treatment of burns infected with P. aeruginosa.     

Dynamics of drug resistance of Vibrio cholerae isolated from surface water reservoirs in Siberia and the Soviet Far East in 1976-1990]

In the study on antibiotic resistance 1383 strains of El Tor Vibrio cholerae isolated from surface water reservoirs in 12 administrative territories of the Siberia and Far East within a period of 15 years were tested. The following antibiotics were used: ampicillin, streptomycin, monomycin, polymyxin, tetracycline, chloramphenicol, rifampicin and nalidixic acid. The resistance was unstable and its pattern was wave-like according to annual changes in the biological cycle. It was especially evident in regard to ampicillin, streptomycin, monomycin and polymyxin. The highest numbers of the strains were resistant to polymyxin, ampicillin and streptomycin (up to 100 per cent in some years). The lowest numbers of the strains were resistant to chloramphenicol (0.4 per cent) and tetracycline (1.9 per cent). No strains resistant to rifampicin and nalidixic acid were isolated. In some cases the antibiotic resistance level depended on the geographical zone where the strain was isolated. A direct quantitative dependence of the resistance level on the MIC was observed: the lower the MIC of the drug was, the lower the number of the strains resistant to it was. Within the 15-year period there was no general tendency to increase the resistance in V. cholerae to the antibiotics used.     

Antibiotic sensitivity and the characteristics of transmissive R plasmids in Shigella belonging to various species]

Sensitivity of 241 Shigella strains isolated from patients at various regions of the USSR in 1975--1978 was tested with respect to 14 antibiotics by the method of serial dilutions. 90.5 per cent of the isolates proved to be resistant to the antibacterial drugs and the greater part of 75.9 per cent of them had multiple resistance. The resistance of the Shigella was most pronounced and frequent with respect to tetracycline, streptomycin, levomycetin, as well as ampicillin and carbenicillin. Gentamicin, cephaloridin, polymyxin M, kanamycin, monomycin, neomycin and rifampicin were highly active against the Shigella. More than 50 per cent of the isolates were sensitive to levomycetin, ampicillin and carbenicillin. Differences in the frequency of the resistant strains and the spectrum of the antibiotic resistance of different Shigella subgroups (species) were observed. The study of 173 multiple resistant Shigella strains showed that about 67 per cent of the strains had a capacity for transduction of the resistance markers into the recipient cells of E. coli. The conjugative R-plasmids were most frequent in Sh. boydii and Sh. sonnei (95 and 95 per cent respectively), less frequent in Sh. flexneri and Sh. newcastle (68 and 53 per cent respectively) and least frequent in the mannitol negative Shigella (25 per cent). The capacity for transduction of R-plasmids in the strains carrying the determinants of resistance to 2 or 3 antibiotics was higher than in the strains carrying the determinant of resistance to one antibiotic. The clinical Shigella strains tested mainly had transmissive R-plasmids of fi--character (79 per cent).     

Drug resistance of opportunistic enterobacteria isolated from various sources]

Resistance of 159 strains of opportunistic enterobacteria to 9 antibacterial drugs was studied. The strains were isolated from man and cattle. It was shown that the overwhelming majority of the isolates (93 per cent) were polyresistant irrespective of the genus. There was a high frequency of the strains resistant to the widely used antibiotics such as chloramphenicol (73 per cent), ampicillin (73.6 per cent) and rifampicin (95.6 per cent) and sulfanilamides (99.3 per cent). Gentamicin and nalidixic acid proved to be the most active against the cultures: 11.9 and 10 per cent of the resistant strains, respectively. The strains of enterobacteria isolated from different sources had a sensitivity to the antibiotics. Multiple antibiotic resistance to at least 5 drugs, variability of the spectra and high resistance were more characteristic of the isolates from the animals. The necessity of a rational use of antibacterial drugs in veterinary is indicated.     

Level and nature of the drug resistance of Shigella flexneri]

Characteristics of antibiotic resistance of 300 strains of Shigella flexner 2a isolated from patients within 1976--1977 in the regions where these bacteria were very rare for a long period of time were studied. It was shown that most of the isolates were resistant to chloramphenicol (88.1 per cent), tetracycline (94.8 per cent), streptomycin (89.1 per cent), polymyxin M (82.4 per cent) and others. 46.5--61.6 per cent of the isolates were resistant to neomycin antibiotics. A high level of the resistance was also noted: the bactericidal effect was registered in 52.0-74.0 per cent of the cultures at a dose of 500--1000 microgram/ml. 91.4 per cent of the strains possessed multiple dug resistance, 78.8 per cent of them being simultaneously resistant to 4--7 drugs. Transmissive R-plasmids were found in 68.8 per cent of the isolates. After exposure to acridine dyes the plasmid nature of the resistance was confirmed in 72.3 per cent of the cultures. Variability of the r-determinant sets in r-plasmids was noted. Strains (64.9 per cent) carrying r-determinants Tc, Cm, Sm and Tc, Cm were more frequent. Strains with one transmissive r-determinant were usually solitary.     

Drug resistance of the causative agent of Grigo'rev-Shiga dysentery (Shigella dysenteriae 1)isolated in the USSR

Forty strains of S. dysenteriae 1 isolated in the USSR within 1986-1988 were tested for their resistance to 11 antibacterial drugs. It was shown that 92.5-97.5 per cent of the isolates were resistant to chloramphenicol (Cm) and tetracycline (Tc), 22.5 per cent to streptomycin (Sm), 17.5 per cent to nalidixic acid (Nal) and 10 per cent to ampicillin (Ap) and polymyxin (Pm). Resistance to Cm Tc (51.4 per cent) and Cm Tc Nal (13.5 per cent) represented the predominating phenotype. 35 per cent of the strains carried conjugative R plasmids. In the majority of the cases, the determinants of resistance to Cm and Tc were transferred, which must define the high frequency of the strains resistant to Cm and Tc. All the tested strains were sensitive to gentamicin, neomycin, rifampicin, cefamezin and ciprofloxacin. Since the strains of S. dysenteriae 1 proved to be highly sensitive to the tested drugs it appeared possible to consider them as the drugs of choice in etiotropic therapy of patients with dysentery caused by the pathogens of the Grigoryev-Shiga group.     

Elimination of mercury,cadmium and antibiotic resistance fromAcinetobacter lwoffi andMicrococcus sp. at high temperature

Resistance determinants for HgCl2 and CdCl2 were eliminated along with a number of antibiotic resistance factors from Acinetobacter lwoffi and Micrococcus sp. at 44 degrees C. These organisms were orginally resistant to HgCl2, merbromin, CdCl2, Pb(NO3)2, benzylpenicillin, erythromycin, carbenicillin, tetracycline and sulfadiazine. Four different types of mutants from A. lwoffi (type I to IV) and one type of mutant from Micrococcus sp. (type V) were obtained, depending on the loss of particular resistance factors for HgCl2, merbromin, CdCl2 and antibiotics. In general, frequency of elimination of all the missing markers was very low (in the range of 10(-3) per bacterium). However, the missing determinants did not revert spontaneously.     

Sensitivity of clinical strains of facultatively anaerobic bacteria to antimicrobial drugs

Six hundred and sixty five samples of clinical materials from patients with various pyoinflammatory diseases were tested for obligatory anaerobes. Anaerobes were detected in 148 samples which amounted to 22.3 per cent of the total number of the samples and to 33.2 per cent of the samples with microbial growth. A total of 171 strains of obligatory anaerobes were isolated. Among them 58.5, 24.5, 16.4 and 0.6 per cent were nonsporulating gramnegative bacilli, grampositive cocci, grampositive bacilli and gramnegative cocci respectively. Sensitivity of the isolated anaerobes was tested with the disk diffusion method. The most active drugs against the tested strains were: nitroxoline, rifampicin, metronidasole, erythromycin, carbenicillin and cefotaxim (4.2, 4.5, 9.3, 10.6, 11.5 and 11.7 per cent of the resistant strains respectively). Gentamicin, polymyxin M, novobiocin and cefazoline were the least active drugs (94.6, 78.9, 65.4 and 50.0 per cent of the resistant strains respectively). Metronidasole, levomycetin, nitroxolin, rifampicin and furazolidone showed the highest activity against bacteroids of the fragilis group (0, 0, 0, 8 and 12.5 per cent of the resistant strains respectively) while gentamicin, polymyxin M, cefazolin, oxacillin, novobiocin and penicillin showed the lowest activity (100, 100, 100, 100, 87.0 and 66.7 per cent of the resistant strains respectively).     

Antibiotic sensitivity and pathogenetic factors of hospital strains of Pseudomonas aeruginosa isolated from patients treated in a resuscitation unit]

Strains of Pseudomonas aeruginosa were isolated from patients treated in the Centre of Thermal Affections in 1985-1989. It was shown that 72.9, 59.3, 33.8 and 54.2 per cent of the isolates were sensitive to cefotaxime, tobramycin, gentamicin and polymyxin, respectively. The study of pathogenicity factors of the isolates revealed that 83 per cent of the strains produced thermolabile enterotoxin, 79.6 per cent of the strains had adhesive activity and 71.1 per cent of the strains produced hemolysin. The study detected combinations of various pathogenicity factors. 42.3 per cent of the isolates had both adhesive and enterotoxigenic properties. Adhesiveness and hemolytic activity were shown by 13.5 per cent of the strains. 16.9 per cent of the strains produced both enterotoxin and hemolysin. Adhesive activity, enterotoxigenicity and hemolysin production were observed in 6.7 per cent of the strains. It was noted that the strains of P. aeruginosa resistant to polymyxin mainly produced enterotoxin (18.6 per cent) and those resistant to cefotaxime had adhesive activity (34.0 per cent).     

Sensitivity of the causative agent of tularemia to antibiotics

Sensitivity of the tularemia causative agent of different geographical races to antibiotics such as streptomycin, tetracycline, gentamicin, rifampicin (20 strains), ampicillin, polymyxin M, erythromycin, oleandomycin (361 strains) and lincomycin (294 strains) was studied. High sensitivity of the tularemi a microbe to streptomycin, tetracycline, rifampicin (MIC of 10 gamma/ml), gentamicin (MIC of 1 gamma/ml) and resistance to 50 gamma of ampicillin and 1000 gamma/ml of polymyxin M were found. Combined use of 50 gamma of ampicillin and 100 gamma/ml of polymyxin M added to the nutrient medium for growth inhibition of the foreign flora on isolation of the tularemia causative agent from the infected material including stable laboratory animal carcases was recommended. Marked differences in sensitivity of the strains of different geographical races to the macrolides and lincomycin were observed. The strains of the non-Arctic and Central Asiatic races were of low resistance to the above drugs (the MIC of erythromycin, oleandomycin and lincomycin were 10--50, 50--400 and 25--100 gamma/ml respectively. Within the holarctic race 40 per cent were low resistant and 60 per cent were highly resistant to these drugs. The above drugs should not be used for treatment of tularemia cases.     

Cefamandole resistance transfer in bacterial strains from two newborn units

Transfer of Cefamandole resistance was demonstrated from strains of Citrobacter freundii as well as from individual strains of Enterobacter cloacae, Acinetobacter anitratus and Klebsiella pneumoniae isolated from patients in two newborn units. In Citrobacter freundii, Cefamandole resistance was transferred always with Cephalotin resistance as well as with a TEM-like beta lactamase (conferring resistance to Ampicillin, Carbenicillin and Azlocillin). Citrobacter freundii strains from Hospital I were completely susceptible to gentamicin, while strains of other species, resistant to Cefamandole plus Cephalotin, were resistant to Gentamicin as well, and transferred this resistance, too. In one Enterobacter cloacae strain from Hospital I, Cefamandole resistance could be separated from resistance to Cephalotin, but only in clones selected with gentamicin and not with any of the cephalosporins. Acinetobacter anitratus strain was also resistant to Cefotaxime, but did not transfer this resistance. It might be concluded that special nosocomial bacteria may carry plasmids conferring a transferable type of resistance to Cefamandole together with resistance to classical cephalosporines. Second cycle of transfers, i.e. between two variants of E. coli K-12 strains confirmed the contransferability of Cefamandole and Cephalotin resistance.     

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.     

Susceptibility of Salmonellae to Cephalosporins and to Nine Other Antimicrobial Agents

Three cephalosporin-related antibiotics and nine other antimicrobial agents were studied for in vitro effectiveness against 54 recently isolated strains of Salmonella. Minimal inhibitory concentrations determined by the plate dilution method demonstrated the following percentages of resistance: ampicillin, 6%; tetracycline, 13%; streptomycin, 52%; sulfadiazine, 94%; cephaloglycin, 96%; and lincomycin, 100%. No strains were resistant to cephalothin, cephaloridine, chloramphenicol, colistimethate, kanamycin, and polymyxin B. The commonest serotype studied, S. typhimurium, showed the greatest antibiotic resistance, with 21% resistant to ampicillin, 36% resistant to tetracycline, and 71% resistant to streptomycin. Cephalothin and cephaloridine were highly effective in vitro but inhibitory concentrations of 20 to 40 mug of cephaloglycin per ml were required for the majority of Salmonella strains.     

鳜鱼细菌性病原的分离鉴定及致病性初步研究

对广东省各地区患病的鳜鱼进行病原分离,通过细菌学鉴定和应用VITEK-AMS-60鉴定系统,并以有关的标准菌株为对照,初步鉴定为温和气单胞菌（Aeromonas sobria）、少动假单胞菌（Pseudomonas paucimobilis）、脑膜脓毒性黄杆菌（Flavobacterium meningosepticum）、施氏假单胞菌（Pseudomonas statzeri）、美人鱼弧菌（Vibrio damsela）、鲁氏不动杆菌     

鲍曼不动杆菌对碳青霉烯类抗生素的耐药性及其基因的分析

目的研究23株鲍曼不动杆菌对碳青霉烯类抗生素的耐药情况及对耐药基因分析,为临床用药提供依据。方法用珠海迪尔DL-96鉴定系统进行细菌鉴定及K-B法进行药敏试验,用碳青霉烯酶4种基因的特异性引物对其进行聚合酶链反应(PCR)扩增和基因型分析,并通过网上GenBank进行比对以确定编码酶基因的类型。结果 23株鲍曼不动杆菌对哌拉西林/他唑巴坦、左旋氧氟沙星、丁胺卡那霉素、多黏菌素B的耐药率分别为80%、45%、30%、10%,对其他抗生素的耐药率均在90%以上。携带D类碳青霉烯酶OXA-23基因有18株(78%),携带OXA-51基因有15株(65%),OXA-24、OXA-58基因引物PCR扩增为阴性,随机各抽取3株OXA-23基因阳性株进行测序后通过在网上GenBank比对与OXA-23标准株99%同源,OXA-51基因阳性株与OXA-51标准株98%同源。结论耐碳青霉烯类抗生素的鲍曼不动杆菌对多黏菌素的耐药率最低,其次是丁胺卡那霉素,其中以携带OXA-23型碳青霉烯酶基因为主,应引起临床高度关注,防止在院内广泛传播。     

Antibiotic sensitivity and pyocin dependence of clinical strains of Ps. aeruginosa]

The effect of antibiotics on clinical strains of Ps. aeruginosa was analyzed. It shown that 92 per cent of the strains had multiple resistance to the most of the antibiotics used in the clinic. All the strains were sensitive to gentamicin and polymyxin. The apyocinogenic strains of Ps. aeruginosa were more sensitive to the effect of the antibiotics than the pyocinogenic ones.     

Aminoglycoside-modifying enzymes in clinical isolates ofAcinetobacter calcoaceticus

Aminoglycoside-modifying enzymes were identified in clinical strains ofAcinetobacter calcoaceticus subsp.anitratus (Herellea vaginicola) isolated between 1971 and 1979. Resistance to kanamycin, neomycin, and lividomycin was explained by an aminoglycoside-3′-phosphotransferase enzyme. The resistance of gentamicin was due to an aminoglycoside 3N-acetyltransferase type I enzyme which had not previously been described in this species. Several strains producing both enzymes showed resistance to kanamycin, gentamicin, lividomycin, neomycin, and sisomicin and susceptibility to tobramycin and amikacin.     

替加环素与多粘菌素B对泛耐药鲍曼不动杆菌体外研究

目的为治愈耐舒普深的泛耐药鲍曼不动杆菌（PDR-Ab）提供新药。方法替加环素采用二倍琼脂稀释法,多粘菌素B用E-test条法测分离目标菌株100株的最低抑菌浓度（M IC）,并用WHONET 5.4软件分析数据。结果多粘菌素B对耐舒普深的泛耐药鲍曼不动杆菌株的M IC值分布情况为：1.5 mg/L为2株,1.0 mg/L为9株,0.75 mg/L为9株,0.5 mg/L为38株,0.38 mg/L为34株,0.25 mg/L为8株,均为敏感;替加环素对耐舒普深的泛耐药鲍曼不动杆菌株的M IC值分布情况为：≥32 mg/L为0株、16 mg/L为2株、8 mg/L为3株、4 mg/L为4株、2 mg/L为6株、1 mg/L为9株、0.5 mg/L为30株、0.25 mg/L为33株、0.125 mg/L为9株、0.06 mg/L为2株、0.03 mg/L为2株,敏感率为95.0%,中敏率为3.0%,耐药率为2.0%。结论替加环素或多粘菌素B是目前对耐舒普深的泛耐药鲍曼不动杆菌最有效药物之一。     

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.