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.     

Characteristics of clinical<Emphasis Type="Italic">Acinetobacter</Emphasis> spp. strains

Resistance to 13 antimicrobial agents, resistance to the bactericidal activity of human serum, hydrophobic properties, lipolytic activity and production of histamine were determined in a total of 50 clinicalAcinetobacter spp. strains (A. baumannii, A. lwoffii, A. calcoaceticus, A. haemolyticus). None of the tested isolates showed resistance to meropenem and none ofA. lwoffii, A. calcoaceticus andA. haemolyticus strains were resistant to amikacin. Forty-six strains (92 %) manifested resistance to ampicillin, 90 % to cefuroxime, 68 % to ciprofloxacin, 58 % to piperacillin, gentamicin and cotrimaxazole, 50 % to cefotaxime, 44 % to amikacin, 42 % to ceftazidime, 38 % to piperacillin/tazobactam, 24 % to netilmicin and 16 % to ampicillin/sulbactam. In particular,A. baumannii andA. calcoaceticus strains showed considerable antibiotic resistance. Thirty-one isolates (62 %) showed serum resistance; intermediate sensitivity was found in 19 isolates (38 %). The majority of the strains (72 %) demonstrated a strongly hydrophobic character; 16 % of isolates exhibited moderate hydrophobic properties. All strains showed lipolytic activity; production of histamine was detected in 14 of 43 strains examined.     

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.     

Resistance of urinary tract infection pathogens and choice of antibacterial therapy in pediatric urologic practice]

The data on antibiotic resistance of the main uropathogens isolated from patients with urinary tract infection in an urologic department (319 isolates) and outpatient and diagnostic units (360 isolates) are presented. It was shown that by the antibiotic resistance the Escherichia coli isolates from the urologic department patients and outpatients did not practically differ: 44.1 and 47.8% of the isolates were resistant to ampicillin, 26.7 and 23.4% were resistant to amoxycillin/clavulanate, 28.9 and 24.9% were resistant to co-trimoxazole and 26.5% was resistance to cefuroxime (outpatients). The basic differences referred to Pseudomonas aeruginosa: resistance to ceftazidime in 38.5% of the isolates and resistance to gentamicin in 36.2% of the isolates. The activity against P. aeruginosa could be arranged as follows in the decreasing order: amikacin = meropenem > imipenem > cefepime = cefoperazone/sulbactam > gentamicin = ceftazidime. Resistance of P. aeruginosa to fluoroquinolones (ciprofloxacin and levofloxacin) remained low (7.4 and 8.0% respectively). No ampicillin resistance was revealed in the isolates of Enterococcus faecalis.     

耐亚胺培南铜绿假单胞菌对左氧氟沙星的耐药性观察

目的对比研究左氧氟沙星和常用的12种抗生素对92株耐亚胺培南铜绿假单胞菌的耐药性.方法药敏试验采用K-B纸片扩散法.结果左氧氟沙星对耐亚胺培南菌株的耐药率为43.48%;显著低于头胞噻肟、头胞西丁、头胞他定、头胞哌酮、氧氟沙星和洛美沙星(P＜0.02或P＜0.001);和诺氟沙星、环丙沙星、阿米卡星、舒普深、妥布霉素的耐药率无差异([ WTBX P＞0.05).结论左氧氟沙星对耐亚胺培南铜绿假单胞菌有良好的抗菌活性.     

Biochemical determinants of aminoglycoside resistance in Gr- microorganisms isolated from urocultures

The investigation was focused on 60 strains of Gr- microorganisms isolated from urocultures and resistant to gentamicin and/or amikacin. Resistance evaluation by the method of Bauer--Kirby with respect to 7 aminoglycoside aminocyclitols (streptomycin, spectinomycin, kanamycin, gentamicin, tobramycin, sisomicin, netilmicin and amikacin) as well as determination of minimal inhibitory concentrations revealed that the most frequently occurring resistance phenotype was streptomycin kanamycin gentamicin sisomicin tobramycin (91.66% tested microorganisms). Approximately 50% of all tested organisms were found to be susceptible to netilmicin. Assays for aminoglycoside-modifying enzymes using 32P ATP and 14C ATP confirmed APH(3')(5")--I and AAD(2") as resistance determinants regarding 4,6-substituted deoxystreptamines. Acetyltransferase determination by the method of Shannon and Phillips and that by van de Klundert et al. most frequently assumes for the formation of AAC(3)-II and AAC(3)-I. Assays utilizing radioactive labels in amikacin-resistant strains determine the enzymes APH(3') and AAD(2")-II.     

Susceptibility to selected antibiotics of Yersinia enterocolitica 03 strains, carrying and not carrying plasmid pYV

A total of 199 clinical strains of Yersinia enterocolitica serotype O3, biotype 4 were tested for their susceptibility to antibiotics (158 strains carried the virulence plasmid pYV and 41 strains did not). 114 isolates were tested by standard disk diffusion method for 21 antibiotics. Almost all tested strains were resistant to ampicillin and cefazolin and susceptible to amoxycillin/clavulanate, cefaclor, cefamandole, cefuroxime, cefotaxime, ceftriaxone, aztreonam, imipenem, gentamicin, amikacin, netilmicin, tetracycline, doxycycline, chloramphenicol, ciprofloxacin, sulphamethoxazole, co-trimoxazole, trimethoprim and furazolidone. In addition minimal inhibitory concentrations (MICs) of 15 antibiotics were determined by agar dilution method for all 199 strains (158 plasmid positive and 41 strains plasmid negative). Third-generation cephalosporins such as cefotaxime and ceftriaxone and a fluoroquinolone (ciprofloxacin) were the most active antimicrobial agents, tested followed by aztreonam, imipenem, trimethoprim, tetracycline, gentamicin, chloramphenicol, amoxycillin/clavulanate, cefaclor, cefuroxime, amikacin, furazolidone and sulphamethoxazole. The present study demonstrated a high susceptibility of clinical strains of Y. enterocolitica to most of the tested antibiotics. In general, there was no significant difference between susceptibility of virulence plasmid pYV positive and virulence plasmid negative strains to antibacterial agents.     

Antibiotic sensitivity of pneumonia pathogens in newborns and problems of antibacterial therapy of the pathologic process]

The results of the bacteriological investigation of the secretion from the trachea, large bronchi and fauces of 36 newborns (including 27 preterms) with severe pneumonia were analyzed. 20 of them were born of women with complicating somatic, obstetric and gynecologic histories: candidiasis, herpes genitalis, chronic endometritis, adnexitis or chronic pyelonephritis that could be the risk of the fetus intranatal infection. During the acute period of pneumonia in the newborns within the first 4-8 days of life mainly Pseudomonas aeruginosa was isolated (51.3 per cent), Staphylococcus epidermidis, S. haemolyticus and Enterococcus faecalis were less frequent (18.9, 8.1 and 5.4 per cent, respectively). Klebsiella pneumoniae, Streptococcus anhaemolyticus and other organisms were extremely rare. On the whole the gramnegative microflora predominated. The study of the antibiotic susceptibility showed that the majority of the P. aeruginosa isolates were susceptible to amikacin and polymyxin B, the isolates susceptible to ceftazidime were less frequent, 20-25 per cent of the isolates were susceptible to ciprofloxacin, cefoperazone and imipenem and practically no isolates were susceptible to gentamicin. The S.epidermidis isolates were susceptible to rifampicin and vancomycin and in rare cases to fusidin and amikacin and resistant to oxacillin. When the treatment course was more than 15 days, the isolates proved to be susceptible to 1/3 of the presently available antibiotics. Because of the host low protective forces, peculiarities of the infection pathways and high frequency of the resistant strains it is valid to include netilmicin, imipenem, cefoperazone and ceftriaxone to the complex therapy of the newborns along with the substitution immunotherapy.     

2005～2008年儿童菌痢病原菌与药敏分析及临床意义

目的了解儿童细菌性痢疾病原菌的分布特征及药敏特点,为临床更严谨更规范使用抗生素提供支持与依据。方法对2005年10月至2008年10月57例儿童菌痢的菌型、药敏及耐药性进行分析。结果儿童细菌性痢疾病原菌亚型分类中宋氏痢疾杆菌（D群）占14．0％,福氏痢疾杆菌（B群）占86．0％;痢疾杆菌对常用抗生素耐药率由低到高依次为头孢噻肟,丁胺卡那霉素,庆大霉素,头孢哌酮,头孢三嗪,头孢他啶,头孢唑啉,环丙沙星,氯霉素,复方新诺明,氨苄青霉素;痢疾杆菌单株对多种抗生素的总耐药率为39．2％,多重耐药率为43,9％,且各组间差异无显著性（χ^2=1．608,P=0．996）,痢疾杆菌的耐药问题依然严重。结论新乡市区儿童细菌性痢疾病原菌亚型分类D组已呈明显上升趋势,但总体仍以B群感染为主（86％）;痢疾杆菌的耐药问题依然严重;对儿童菌痢选用抗生素应结合药敏首选头孢噻肟等第三代头孢类抗生素或头孢唑啉,年长儿也可选用丁胺卡那霉素、庆大霉素等氨基苷类,而以环丙沙星为代表的喹诺酮类药物不宜作为儿童尤其7岁以下小儿菌痢的备选药物;氯霉素、复方新诺明及氨苄青霉素已不再作为小儿菌痢的抗菌选择。     

Pseudomonas aeruginosa and beta-lactam resistance phenotypes (Tunisia 1989-1990)]

366 strains of P. aeruginosa were studied. More than half of samples were issued from urology (40%) and general surgery (21%) and samples are mostly urine specimens (46%). The phenotypes of resistance to 3 beta-lactams (respectively ticarcillin, cefotaxime and ceftazidime) showed that 73% of the strains were wild phenotype (SSS-SIS-SRS). The MIC of ticarcillin +/- clavulanic acid, azlocillin, cefoperazone, cefsulodin, cefotaxime and ceftazidime against 93 strains chosen among different phenotypes of resistance showed that ceftazidime is the most active beta-lactam, 93% of strains being inhibited by 16 micrograms/ml. These MIC and iodometric test performed on 33 strains with ticarcillin MIC > 128 mg/l showed that acquired resistance was non enzymatic in 21% of cases and was related to beta-lactamase production in 79% of cases.     

Aminoglycosides resistance in clinical isolates of Staphylococcus aureus from a University Hospital in Bialystok, Poland

Staphylococcus aureus obtained from a University Hospital in Poland were characterized in relation to resistance to aminoglycoside antibiotics and the distribution of the genes encoding the most clinically relevant aminoglycoside modifying enzymes (AMEs). Of a total of 118 S. aureus, 45 (38.1%) isolates were found to be resistant to at least one of the tested antibiotics. All aminoglycoside resistant isolates except one 44 (97.8%) were resistant to kanamycin. The majority of strains 37 (82.2%) and 32 (71.1%) expressed resistance to neomycin and tobramycin, respectively. Eleven strains (24.4%) were resistant to gentamicin or amikacin. All S. aureus strains were sensitive to netilmicin. The most prevalent resistance gene was aac(6')-Ie+aph(2') found in 13 (28.9%) strains and 12 (26.7%) isolates carried ant(4')-Ia gene, whilst aph(3')-IIIa gene was detected in only 7 (15.6%) isolates. Additionally, the ant(6)-Ia and str genes were detected in 14 (31.1%) and 2 (4.4%) strains, respectively. Ten (22.2%) strains resistant to amikacin, tobramycin, kanamycin or neomycin did not harbor any of the above-noted genes.     

嗜麦芽寡养单胞菌临床分布特征与耐药分析

目的了解湖州市中心医院嗜麦芽寡养单胞菌临床分布特征与耐药性。方法采用常规方法分离,用VITE-COMPACT2全自动微生物分析仪进行菌种鉴定,用K—B法进行药敏试验。结果分离到嗜麦芽寡养单胞菌810株,复方新诺明耐药菌株48株（分离率5．9％）。标本来源主要来自ICU室,其次呼吸科,大部分来自痰液标本（约占89．2％）,年龄段以中老年人比率最高。嗜麦芽寡养单胞菌对亚胺培南、美罗培南、头孢吡肟、哌拉西彬他坐巴坦、庆大霉素、妥布霉素、阿米卡星高度耐药;头孢他啶、替卡西林／克拉维酸、环丙沙星耐药率为33．7％～58．2％;头孢哌酮／舒巴坦、左氧氟沙星、米诺环素、复方新诺明耐药率低于30．0％。复方新诺明耐药菌株对头孢哌酮／舒巴坦、左氧氟沙星和米诺环素耐药率分别为60．4％、91．7％和2．0％,对其余抗菌药物耐药率达100．0％。复方新诺明耐药菌株与复方新诺明敏感菌株相比,耐药情况更严重,其中对三、四代头孢菌素、喹诺酮类耐药率显著高于复方新诺明敏感菌株（P〈0．01）;对碳青霉烯类、青霉素类、氨基糖苷类抗菌药物耐药率与复方新诺明敏感菌株相比,差异无统计学意义（P〉0．05）。结论嗜麦芽寡养单胞菌呈高度耐药,对头孢哌酮／舒巴坦、左氧氟沙星、米诺环素、复方新诺明尚敏感,但对复方新诺明耐药的嗜麦芽寡养单胞菌耐药现象更严重。应重视嗜麦芽寡养单胞菌引起的院内感染,尽量减少不必要的侵人性操作,加强抗菌药物的合理规范使用。     

Antibiotic susceptibility of clinical isolates of Pseudomonas aeruginosa

Three hundred and twenty two clinical isolates of Pseudomonas aeruginosa collected in Morelia, México, were analyzed for in vitro susceptibility to five antibiotics by agar dilution tests. Antibiotic resistance was shown by 50% of total isolates. Frequencies of resistance were: streptomycin, 47%; gentamicin, 13%; tobramycin, 8%; and carbenicillin, 7%; no amikacin resistance was found. The more common resistance patterns were streptomycin, gentamicin-streptomycin, and tobramycin-gentamicin-streptomycin. Resistance to either tobramycin, gentamicin or carbenicillin was found mainly in pyocin type 10 isolates. The proportion of antibiotic resistant isolates ranged from 37 to 75% in four hospitals, and amounted 24% in three clinical laboratories.     

Influence of an extended incubation period on values of minimum inhibitory concentrations of antibiotics in Stenotrophomonas maltophilia clinical strains

In 106 Stenotrophomonas maltophilia clinical strains the susceptibility to 19 kinds of antibiotics was tested by the broth dilution micromethod at 24 h and 48 h incubation. Isolated strains demonstrated the lowest frequency of resistance to cotrimoxazole (7.5% of resistant strains at 24 h incubation and 18.9% at 48 h), ofloxacin (13.2% and 30.2%), ciprofloxacin (19.8% and 50.9%) and to cefoperazone/sulbactam (20.8% and 37.7%). The smallest growth of the number of resistant strains after extended incubation was recorded in gentamicin (by 10.4%), ceftazidime (by 11.3%) and cotrimoxazole (by 11.4%). On the contrary, the largest growth of resistance was demonstrated in cefoperazone and ciprofloxacin (by 31.1%). Average values of the growth of minimum inhibitory concentrations (MICs) were lowest in ciprofloxacin and ofloxacin (2.3 times) and highest in piperacillin/tazobactam (4.5 times) and piperacillin (5.0 times). As far as the stability of MIC is concerned, the largest occurrence of strains with the MIC growth doubled as a maximum was found in ceftazidime (78.4%), ofloxacin (76.1%) and ciprofloxacin (75.3%), the smallest in piperacillin/tazobactam (43.2%) and piperacillin (38.9%). The importance of incubation extended to 48 h during the testing of S. maltophilia strains was noted for correctly setting their susceptibility to antibiotics.     

Antibiotic utilization and Pseudomonas aeruginosa resistance in intensive care units

Pseudomonas aeruginosa is one of the most frequent and dangerous pathogens involved in the etiology of severe nosocomial infections. A retrospective observational study was conducted at all intensive care units of the University Hospital in Olomouc, Czech Republic (155 ICU beds). Complete antibiotic utilization data of the ICUs in the period of 1999 to 2008 were processed according to ATC/DDD system and expressed in defined daily doses per 100 bed-days (DBD). Utilization of meropenem, imipenem, ciprofloxacin, ofloxacin, pefloxacin, gentamicin, amikacin, ceftazidime, cefoperazone, cefoperazone/sulbactam and piperacillin/tazobactam was measured. Pseudomonas aeruginosa strains were isolated from clinical material obtained from patients hospitalized in ICUs. During the ten-year period, utilization of the entire group of antibiotics monitored grew. It increased from 23.52 DBD in 1999 to 27.48 DBD in 2008 with a peak of 33.04 DBD in 2007. P. aeruginosa accounted for as much as 42% of pneumonias and 23% of surgical wound infections. Our results show that P. aeruginosa strains became gradually resistant to all antibiotics used in the treatment of the infections caused by them, with the exception of amikacin and piperacillin/tazobactam.     

Analysis of the etiological structure and dynamics of antibiotic resistance in the causative agents of suppurative inflammatory diseases in the patients at a large general hospital

The structure of the causative agents isolated from patients with pyoinflammatory infections in 1980-1983 was analysed. It was shown that the surgical and urological infections were mainly caused by gram-negative bacteria. The other pyoinflammatory infections were mainly due to gram-positive cocci. A relatively high frequency of the strains of gram-negative bacteria, especially among Pseudomonas spp. and Enterobacter spp., resistant to aminoglycoside antibiotics, such as gentamicin, sisomycin and tobramycin with preserved sensitivity to amikacin and netilmicin in the majority of the strains was shown. Among the beta-lactam antibiotics cephotaxim and cephalotin were most active against gram-negative bacteria and staphylococci, respectively. The majority of the antibiotic resistant strains of gram-negative bacteria had analogous structures and levels of resistance to 7-12 antibiotics which might indicate the occurrence of 1-2 resistance plasmids among the clinical strains.     

Resistance to antibiotics and heavy metals of Pseudomonas aeruginosa isolated from natural waters

The resistance patterns of Pseudomonas aeruginosa strains isolated from freshwater and seawater to different antimicrobial agents and heavy metals were studied. It was found that resistance in these environments is linked to the level of faecal pollution. All strains were resistant to ampicillin and tetracycline but sensitive to carbenicillin, amikacin, tobramycin, and colistin, and to the assayed concentrations of silver, cadmium, lead, and molybdenum. Resistance to gentamicin, sulphadiazine, mercury, arsenic, and chromium was variable, so their use as epidemiological markers was considered. There was a close relationship between the degree of pollution and the frequency of heavy metal resistant strains of Ps. aeruginosa. The highest frequencies of resistance to mercury and arsenic were obtained from marine environments with little faecal pollution, where the highest incidence of multi-resistant strains was also observed.     

Resistance to antibiotics and heavy metals of Pseudontonas aeruginosa isolated from natural waters

The resistance patterns of Pseudomonas aeruginosa strains isolated from freshwater and seawater to different antimicrobial agents and heavy metals were studied. It was found that resistance in these environments is linked to the level of faecal pollution. All strains were resistant to ampicillin and tetracycline but sensitive to carbenicillin, amikacin, tobramycin, and colistin, and to the assayed concentrations of silver, cadmium, lead, and molybdenum. Resistance to gentamicin, sulphadiazine, mercury, arsenic, and chromium was variable, so their use as epidemiological markers was considered. There was a close relationship between the degree of pollution and the frequency of heavy metal resistant strains of Ps. aeruginosa. The highest frequencies of resistance to mercury and arsenic were obtained from marine environments with little faecal pollution, where the highest incidence of multi-resistant strains was also observed.     

Inactivation of aminoglycosides by beta-lactams of the penicillin and cephalosporin groups

Interaction of carbenicillin with kanamycin, gentamicin, tobramycin, and amikacin, as well as that of cefotaxime with the same aminoglycosides were studied. It was shown that carbenicillin inactivated aminoglycosides in a patient's plasma, urine, rH 5.3-8.44, and in buffer solutions, pH 3.7, 7.5 and 9.25. The inactivation level was the least in acid media. The mechanism of the inactivation was elucidated: opening of the carbenicillin beta-lactam ring occurred at the start.     

Activity of antibacterial preparations against the causative agent of pseudotuberculosis in vitro

Antibacterial activity of 32 chemotherapeutics against 15 strains of Yersinia ++pseudotuberculosis was studied in vitro. The majority of the strains or 80% were sensitive to penicillins, cephalosporins, monobactams, aminoglycosides, tetracyclins , anzamycins, fluorine derivatives of quinolonecarboxylic acid, levomycetin and a combination of trimethoprim and ++sulfamethoxazole. It was shown that with respect to the Y. pseudotuberculosis strains with multiple antibiotic resistance, the fluorine derivatives of quinolonecarboxylic acid (ciprofloxacin, norfloxacin and enoxacin), tetracyclines, netilmicin, amikacin, cefotaxime and cefazolin were promising for in vivo studies.