Antibiotics in the treatment of wounds in the victims of the earthquake in the Armenian SSR

Purulent wounds in 88 victims of the Armenian earthquake with the syndrome of long-term squeezing were examined microbiologically and the experience with using antimicrobial drugs for their treatment was analyzed. In all the cases microbial associations were detected, coliform and nonfermenting gram-negative bacilli, enterococci, anaerobes and yeast-like fungi being isolated from 80, 20, 15 and 25 per cent of the patients respectively. 130 bacterial strains were studied in detail. 80 to 100 per cent of the bacterial isolates were resistant to the antibiotics routinely used in surgical practice, i.e. benzylpenicillin, tetracycline, levomycetin, kanamycin, cephalothin and cefazolin and highly sensitive to new antimicrobial drugs belonging to ureidopenicillins (mezlocillin), quinolones (ciprofloxacin) and cephalosporins of the 3rd generation (cefoperazone and ceftazidime). Retrospective estimation of the antibiotic therapy revealed its inadequacy in 55.7 per cent of the patients for the most part because of the isolates resistance. The 19 variants of the antibiotic use prescribed by the physicians mainly included penicillins, aminoglycosides and their combinations (in 67.2 per cent of the cases). The use of the highly efficient drugs of the groups of ureidopenicillins and quinolones was extremely rare which was likely due to lacking of information on the drugs.     

Efficacy of a combination of dioxidine with beta-lactam antibiotics in the prevention and treatment of purulent-inflammatory complications

Schemes for prevention and treatment of purulent inflammatory complications were developed on the basis of in vitro studies on antimicrobial activity of dioxidine and 7 beta-lactam antibiotics such as mezlocillin, carbenicillin, ampicillin, cefotaxime, cefoxitin, cefuroxime and cephalothin under conditions of aero- and anaerobiosis with an account of the isolated microflora, its sensitivity to antibacterial agents and conditions required for vital activity of obligate anaerobes in humans, i.e. decreased partial oxygen pressure, low oxidation-reduction potentials and high tissue concentrations of carbon dioxide. The use of dioxidine in combination with the antimicrobial drugs enabled one to decrease the number of cases with purulent inflammatory complications after large intestine esophagoplasty to 30.4 per cent against 67.5 per cent in the control group of the patients untreated preventively with the antibacterial drugs. The number of cases with similar complications after gastrectomy amounted to 16.1 per cent against 62 per cent in the control. The use of dioxidine+ in combination with ampicillin and cefotaxime in treatment of purulent necrotic affections of the foot in patients with diabetes mellitus enabled one to increase the number of satisfactory outcomes by 32 per cent, to decrease the number of high amputations by 21.9 per cent and to lower the number of deaths more than 2-fold as compared to the results in the control group of the patients subjected to chemotherapy based on sensitivity of the aerobic microflora alone.     

The comparative activity of cefepime and other current antibiotics against microorganisms isolated from patients in pediatric intensive therapy units]

Comparative activity of cefepime, ceftazidime, ceftriaxone, ciprofloxacin, imipenem and piperacillin/tazobactam against isolates from patients of pediatric intensive care units within October-December 1998 was studied. The isolates were identified with the Walkaway-40 System. The antibiotic susceptibility was evaluated by the E-test on the Mueller-Hinton II agar. The data were interpreted in accordance with the NCCLS. The number of the isolates totaled 100. Among them not more than 10 to 12 strains belonged to the same species. 92 per cent of the isolates was susceptible to cefepime and 70 to 75 per cent of the isolates were susceptible to the third generation cephalosporins. Piperacillin/tazobactam proved to be highly susceptible, the number of the isolates resistant and moderately resistant to it being 6 and 1 per cent respectively. The results showed that cefepime was intermediate between the third generation cephalosporins and carbapenems.     

Comparative study of the antibacterial activity of aminoglycoside antibiotics and their combinations with carbenicillin against Pseudomonas aeruginosa

Antibacterial activity of 7 aminoglycoside antibiotics and combinations of tobramycin or gentamicin with carbenicillin was studied with respect to 33 clinical strains of Ps. aeruginosa. Tobramycin, sisomicin, gentamicin and amicacin showed high levels of antibacterial activity. Tobramycin and sisomicin were 3-4 and 2 times more effective than gentamicin. 100 per cent of the Ps. aeruginosa isolates was sensitive to tobramycin and amicacin. The number of the isolates sensitive to sisomicin and gentamicin amounted to 97 and 94 per cent respectively. The respective numbers for streptomycin and kanamycin were 32 and 11 per cent. No monomycin sensitive isolates were detected. Combination of tobramycin or gentamicin with carbenicillin increased the antibacterial activity of the aminoglycoside antibiotics by 2-16 times and that of carbenicillin by 2-32 times. The synergistic effect of gentamicin or tobramycin with carbenicilin was observed with respect to 50 and 58 per cent of the isolates respectively. No antagonistic effect was detected on the combined use of the antibiotics. The majority of the isolates (96 per cent) were sensitive to combinations of carbenicillin in a concentration of 50 micrograms/ml with tobramycin or gentamicin in concentrations of 0.15 or 0.3 micrograms/ml respectively.     

Comparative characteristics of the antibioticograms and biological properties of the staphylococci isolated from patients with various eye diseases]

A total of 1488 examinations of the conjunctival content of patients with various ophthalmic diseases were performed within 5 years (1973--1977). 989 (66.4 per cent) cultures were isolated. Staphylococci were isolated in 79.2 per cent of the patients irrespective of the diagnosis. The plasma-coagulating strains were isolated in 43.6 per cent of the patients with acute conjunctivitis. The plasma-negative staphylococci were more frequent in chronic conjunctivitis (83.5 per cent). A total of 188 strains were studied according to 18 tests. Determination of the antibiotic sensitivity showed that the number of the benzylpenicillin and tetracycline resistant strains among the plasma-coagulating staphylococci was higher in the patients with acute ophthalmic diseases. In chronic conjunctivitis no differences in the antibiotic sensitivity of the plasma-coagulating and plasma-negative strains were noted. Similar antibiotic sensitivity of all plasma-negative staphylococci irrespective of the diagnosis was found. High biological activity of the plasma-negative staphylococci was shown: 74.1 per cent of the isolates possessed phosphatase, 59.8 per cent possessed protease and 88.4 per cent a lysozyme-like enzyme. The strains isolated in chronic conjunctivitis produced protease more frequently that those isolated in acute ophthalmic diseases.     

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).     

Component composition and admixtures of related compounds in commercial preparations with an erythromycin base

Chromatographic purity of erythromycin base preparations manufactured in the USSR with various technological procedures and those of 4 foreign firms was studied. All the preparations studied in addition to the main component of erythromycin A contained 5 to 7 per cent of erythromycin C and about 1.5 to 3.5 per cent of a non-identified component possessing a somewhat lower chromatographic mobility than erythromycin C. The admixture of 0.5--1 per cent of anhydroerythmycin was found in many erythromycin preparations. The preparations of some foreign firms contained also a number of additional substances. It was shown that the antimicrobial activity of anhydroerythromycin was 50-60 times lower than that of erythromycin. Direct correla;ion between the level of the antimicrobial activity of the market prepaetions of erythromycin and the level of its chemical purity was noted.     

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.     

Isolation and characterization of endophytic Streptomyces strains from surface-sterilized tomato (Lycopersicon esculentum) roots

AIMS: To isolate endophytic Streptomyces strains from tomato and examine their antimicrobial activity. METHODS: Endophytic Streptomyces strains were isolated using surface-sterilization methods and identified by morphological characteristics. Antimicrobial activities were measured by the agar plate sensitivity method. Antifungal activity in vivo was measured by seedling mortality in infested soils. RESULTS: Twenty-one per cent of endophytic streptomycete isolates produced antibacterial metabolites and 41% produced antifungal metabolites in S medium. Sixty-five per cent of the most frequently isolated strains inhibited the growth of Rhizoctonia solani by the antibiosis assay but only 32% produced metabolites active against R. solani in S medium. Growth promotion and enhanced disease resistance of seedlings inoculated with Streptomyces sp. strain S30 were observed in tomato but not in cucumber seedlings. CONCLUSIONS: Endophytic Streptomyces spp. strains were successfully isolated using stringent methods and strain S30 promoted growth and enhanced resistance to R. solani in tomato seedlings. SIGNIFICANCE AND IMPACT OF THE STUDY: Endophytic streptomycetes showing antifungal activity in vitro and in vivo may indicate the potential for their use as biocontrol agents particularly of R. solani disease of tomato seedlings.     

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.     

The structure and antibiotic sensitivity of the causative agents of community-acquired infectious diseases of bacterial origin in children]

Four hundred and forty pediatric patients at the age of 7 days to 15 years with various infections admitted to the Hospital within a month were examined. The biological material was inoculated to blood agar on the first days of the patient admittance to the Hospital and after the growth the organisms were isolated and identified. Antibiotic susceptibility of the isolates was assayed with the disk diffusion method. 479 strains in all were tested. The most frequent cases requiring hospitalization and antibiotic therapy were those of respiratory tract infections (54.09 per cent), urinary tract infections (26.36 per cent), cutaneous and subcutaneous fat diseases, gastrointestinal diseases and others (about 25 per cent of the cases in all). The main pathogens were Streptococcus viridans, S.aureus and S.epidermidis, as well as Enterobacteriaceae (chiefly E.coli) whose frequencies were practically equal (in 25-35 per cent of the cases). The Pneumococcus isolates amounted to 6.3 per cent. Nonfermenting bacteria (Pseudomonas aeruginosa and Acinetobacter) and some representatives of Enterobacteriaceae (Citrobacter, Serratia, Morganella) were isolated from 7 per cent of the patients. The frequency of Klebsiella and Enterobacter was about 11 per cent. The main pathogens were tested for their susceptibility to amoxycillin/clavulanic acid, ampicillin, oxacillin and gentamicin. The least active antibiotic was ampicillin. 88.8 per cent of the E.coli isolates and 100 per cent of the Klebsiella, P.mirabilis, Morganella, Citrobacter, Enterobacter and Serratia isolates were resistant to it. 53.2 per cent of the Streptococcus isolates including 64.5 per cent of the Pneumococcus isolates were as well resistant to ampicillin. 59.5 per cent of the Streptococcus isolates (mainly S.viridans and Enterococcus) was susceptible to oxacillin, 22.2 per cent of them being moderately susceptible. 62.5 per cent of the Pneumococcus isolates and 78.1 per cent of the Staphylococcus isolates were also susceptible to oxacillin. The highest susceptibility of the isolates was that to amoxycillin/clavulanic acid, i.e. 90.1 per cent of the strains, 79.9 per cent of them being highly susceptible. All the isolates of Citrobacter, Serratia and Morganella and some isolates of P.aeruginosa, Acinetobacter, Enterobacter, Klebsiella and E.coli were resistant to amoxycillin/clavulanic acid. As for the latter 5 organisms their susceptibility to amoxycillin/clavulanic acid was comparable with that to gentamicin. The susceptibility of the Streptococcus and Staphylococcus isolates to amoxycillin/clavulanic acid was significantly much higher than that to oxacillin, gentamicin and ampicillin: 93 per cent of the Streptococcus isolates (62.7 per cent of the Pneumococcus isolates) and 90.7 per cent of the Staphylococcus isolates.     

Sensitivity of Pseudomonas aeruginosa to Normal Serum and to Polymyxin

Strains of Pseudomonas aeruginosa isolated from clinical material were very variable in their sensitivity to the bactericidal action of normal serum mediated by the complement system. Fifty per cent killing end points ranged from 0.015 ml to greater than 0.4 ml. Most of the strains with relatively greater sensitivity to serum were isolated from patients with cystic fibrosis. Immunization of rabbits resulted in antisera with enhanced levels of bactericidal antibody, except with one strain which was resistant to the bactericidal action of normal serum and antiserum. When P. aeruginosa was cultivated at 41 C instead of at 37 C, it was significantly more sensitive to serum and to several antibiotics, thereby implicating fever as a host defense mechanism in Pseudomonas infections. In contrast to their heterogeneity to serum bactericidal activity, the strains were relatively homogeneous in their sensitivity to polymyxin, with no apparent association between their sensitivity to the two antimicrobial agents.     

Prolonged antibacterial action of polymer coated suture materials]

The antimicrobial activity of capromed, a surgical polymer-coated sutural material containing dioxidine, quinoxidine or gentamicin was studied in vitro and in vivo. Capromed was shown to be active against the hospital strains of S. aureus, E. coli, Proteus spp., Klebsiella spp. and P. aeruginosa. The antimicrobial activity of ADH and AG threads was preserved for 3 to 4 days after implantation. The DH-2 and G-2 threads preserved their activity for 6 to 7 days. It was concluded that the duration of thread antimicrobial activity depended on the properties of the polymer coating the thread. Capromed was applied to 280 operation wounds in 275 patients. There was no wound suppuration in the group of patients after pure operations (n = 62). In the group of patients after conditionally pure operations (n = 130) suppuration was observed in 2 patients (1.3 per cent). In patients with contaminated wounds (n = 88) suppuration in 5 of them (5.7 per cent) was recorded. The total number of the purulent complications after using capromed in surgical operations amounted to 2.5 per cent. In the control group purulent complications were stated in 8.2 per cent of the cases.     

Sensitivity of Shigella to antibiotics]

Three hundred and twenty two Shigella cultures isolated from dysentery patients within 1986-1989 were tested with the use of standard paper disks for their sensitivity to levomycetin, streptomycin, tetracycline, monomycin, neomycin, kanamycin, erythromycin, gentamicin, carbenicillin, ampicillin, oxacillin, methicillin and doxycycline. The number of the cultures belonging to Shigella sonnei amounted to 85.1 per cent of the total number of the strains studied. 91.9, 89.5, 87.3, 87.3, 80.1 and 80.1 per cent of the cultures were sensitive to gentamicin, kanamycin, carbenicillin, neomycin, levomycetin and ampicillin, respectively. 99.4 per cent of the isolates were resistant to streptomycin and 97.2 per cent were resistant to tetracycline. The sensitivity to erythromycin remained rather high (70.2 per cent). The overwhelming majority of the Shigella sonnei isolates had multiple resistance.     

Enterobacterial sensitivity to beta-lactam antibiotics]

The susceptibility to betalactams of 868 enteric bacteria isolated from the patients at the hospital was studied. The isolated pathogens included: E. coli (549), Klebsiella sp. (195), Serratia sp. (124). Ampicillin and cefazoline demonstrated the lowest activity. Cefotaxime, ceftazidime and imipenem were active against 90 per cent of isolates. Among E. coli isolates the susceptibility to the above mentioned drugs was the following: 95.1, 96.9, 99.3 per cent, among Klebsiella sp.--89.7, 88.7, 97.9 per cent, among Proteus sp.--89.5, 90.3, 91.9 per cent respectively. Thus cefotaxime may be used in antibacterial empiric therapy if Pseudomonas aeruginosa infection is excluded.     

Lactic acid bacteria from healthy oral cavity of Thai volunteers: inhibition of oral pathogens

The aims of the present study were to screen and characterize the antimicrobial lactic acid bacteria which were isolated from healthy oral cavities of Thai volunteers, and to characterize their inhibiting substances. Among 3790 isolates (suspected to be lactic acid bacteria) from 130 volunteers, five showed an appreciable effect against Sarcina lutea ATCC 9341, Bacillus cereus ATCC 11778, Escherichia coli ATCC 25922, Staphylococcus aureus ATCC 6538, Streptococcus mutans DTMU 1, Strep. salivarius DTMU 1, Strep. sanguis DTMU 1, Candida albicans ATCC 13803 and C. albicans DTMU 2, as well as the oral pathogens. These antimicrobial isolates included L17 and N14 which showed the antibacterial activity, D14 which showed the anticandidal activity, and D6 and N8 which showed both the antibacterial and anticandidal activities. The isolates were later found to be facultative anaerobic, Gram-positive, non-spore-forming, non-capsule-forming and catalase-negative bacilli. They could utilize casein but could not hydrolyse starch, and they produced hydrogen peroxide and bacteriocins. Their antimicrobial potentials were found to be affected by pH, catalase, proteolytic enzymes and temperature. The activity was partially inactivated after catalase treatment, significantly declined at pH > or =9.0 or after trypsin and pepsin treatments, and also reduced after heating at > or =100 degrees C. However, the antimicrobial activity of these five isolates was somewhat resistant to heat. When the isolates were tested for their antimicrobial sensitivity, they were shown to be sensitive to a number of antimicrobial agents. The final identification revealed that D6, D14 and N14 were Lactobacillus paracasei subsp. paracasei, and L17 and N8 were Lact. rhamnosus.     

Prevalence of bacteriocin activities and bacteriocin-encoding genes in enterococcal clinical isolates in Iran

The aim of the project was to isolate and characterize bacteriocin-producing enterococci, as well as determine the prevalence of enterocin structural genes in 187 enterococcal clinical isolates from the northwest of Iran. The isolates were screened for antibacterial activity against 15 different indicator strains. The proteinaceous nature of the antimicrobial substances was confirmed by sensitivity to proteinase K; their stability to heat treatment was tested at 60 °C and 100 °C for 20 and 10 min, respectively. The PCR method was applied to detect previously identified enterocin genes. Our results showed that 38 (20.3%) of the enterococcal isolates were considered to be potential bacteriocinogenic strains. Furthermore, genes encoding diverse bacteriocin are highly distributed among clinical enterococci, and the strains with multi-bacteriocin genes displayed high antimicrobial activity. Enterocin A, enterolysin A, and enterocin L50A/B were the most abundant structural genes detected in bacteriocinogenic strains. This work is the first survey on the prevalence of bacteriocin genes among clinical enterococci in Iran that has isolated a strain with high antimicrobial activity and sensitivity to clinically relevant antibiotics.     

Characteristics of the antibiotic sensitivity of nitrofuran--resistant Gram-negative bacteria of clinical origin]

494 persons with various purulent inflammatory diseases were examined. Gram-negative nitrofuran resistant organisms isolated from the clinical material were found in 22.9 per cent of the cases. Representatives of Enterobacteriaceae, Klebsiella-Enterobacter-Serratia (26.8 per cent), Proteus-Providencia (16.8 per cent) and E. coli-Arizona-Citrobacter (16.1 per cent) predominated. Pseudomonas (32.1 per cent) and Acinetobacter (5.3 per cent) predominated among the aerobic gram-negative bacteria. Sensitivity of 131 strains to 10 chemotherapeutic drugs was determined. 60.4 per cent of the aerobic and 44.2 per cent of the Coli bacteria had multiple drug resistance (to 5 and more drugs). The organisms isolated from the urine and wound excretion were most resistant. Representatives of Pseudomonas and Klebsiella-Enterobacter predominated among the polyresistant cultures. High sensitivity of the isolates to gentamicin, carbenicillin and nalidixic acid was noted.     

Microbiological monitoring for the causative agents of nosocomial infections (exemplified by resuscitation and intensive therapy units)]

More than 900 isolates from at least 1500 patients were tested within 1996-1998. Gram-negative organisms were the main pathogens isolated from patients with different forms of nosocomial complications such as late pneumonia, associated with artificial ventilation of the lungs, and various secondary wound or urinary tract infections. The prevalence of Pseudomonas aeruginosa was stated. Antibioticograms showed that the most active drugs were imipenem (more than 90 per cent of the susceptible isolates) and ticarcillin/clavulanate (48-58 per cent of the susceptible isolates). The activity of ticarcillin/clavulanate (Timentin) was practically the same as that of imipenem against 21 strains of P.aeruginosa isolated from the blood and cerebrospinal fluid of 21 patients with sepsis and 3 patients with secondary purulent meningitis.     

Antimicrobial resistance and virulence genes of Escherichia coli isolates from swine in Ontario

A total of 318 Escherichia coli isolates obtained from diarrheic and healthy pigs in Ontario from 2001 to 2003 were examined for their susceptibility to 19 antimicrobial agents. They were tested by PCR for the presence of resistance genes for tetracycline, streptomycin, sulfonamides, and apramycin and of 12 common virulence genes of porcine E. coli. Antimicrobial resistance frequency among E. coli isolates from swine in Ontario was moderate in comparison with other countries and was higher in isolates from pigs with diarrhea than in isolates from healthy finisher pigs. Resistance profiles suggest that cephamycinases may be produced by > or = 8% of enterotoxigenic E. coli (ETEC). Resistance to quinolones was detected only in enterotoxigenic E. coli (< or = 3%). The presence of sul3 was demonstrated for the first time in Canada in porcine E. coli isolates. Associations were observed among tetA, sul1, aadA, and aac(3)IV and among tetB, sul2, and strA/strB, with a strong negative association between tetA and tetB. The paa and sepA genes were detected in 92% of porcine ETEC, and strong statistical associations due to colocation on a large plasmid were observed between tetA, estA, paa, and sepA. Due at least in part to gene linkages, the distribution of resistance genes was very different between ETEC isolates and other porcine E. coli isolates. This demonstrates that antimicrobial resistance epidemiology differs significantly between pathogenic and commensal E. coli isolates. These results may have important implications with regards to the spread and persistence of resistance and virulence genes in bacterial populations and to the prudent use of antimicrobial agents.