Increasing ciprofloxacin resistance among prevalent urinary tract bacterial isolates in Bangladesh

Ciprofloxacin was evaluated along with other commonly used antibiotics against a total of 425 clinical isolates obtained from urine samples. Samples were collected from outdoor patients from different parts of Dhaka city. Susceptibility tests were done by the standardized disk diffusion method. Among the tested drugs, the percent susceptible rates observed were: ciprofloxacin (74%), ampicillin (29%), cephalexin (54%) and trimethoprim-sulfamethoxazole (43%) tested against all organisms; gentamicin (73%) tested against gram-negative organisms and erythromycin (72%) tested against gram-positive organisms. Ciprofloxacin showed better activity against gram-negative isolates (80%) compared to the other antibiotics. However, strains highly resistant to ciprofloxacin were detected among commonly isolated gram-negative urinary pathogens: Escherichia coli (18%), Klebsiella species (19%) and Pseudomonas species (30%). Overall susceptibility rate for gram-positive cocci was significantly low for all the antibiotics tested including ciprofloxacin (62%). Minimal inhibitory concentration (MIC) of ciprofloxacin was measured for all resistant and susceptible urinary tract infection (UTI) isolates. This study indicates emerging ciprofloxacin resistance among most UTI bacterial pathogens. Increasing resistance against ciprofloxacin demands coordinated monitoring of its activity, and rationale use of the antibiotic in UTI.     

Medical mummies: the history of the Burns Collection

Of the 43 Aeromonas spp. isolated from various clinical samples 94% isolates were Beta-lactamase producers. The isolates were tested for sensitivity by disc diffusion method which is commonly used in Pakistan. MIC was determined by using Epsilometer test (E-test) method. More than 80% isolates were sensitive to cephalosporins and quinolones. However, resistance to commonly used antibiotics was very high, 94% isolates were resistant to ampicillin which corresponds to the betalactamase production. More than 60% of the isolates were resistant to cotrimoxazole and 40% to chloramphenicol, hence quinolones and cephalosporins appear to be the drugs of choice for treating serious Aeromonas infections. The MIC range of Aeromonas was best for cefotaxime < 0.06 - 1.0 ug/ml. MIC 90 for cefotaxime was 0.50 ug/ml, for imipenem 0.25 ug/ml and for ciprofloxacin 2.0 ug/ml.     

Emerging quinolone-resistant Salmonella in the United States

We conducted a national survey of antimicrobial resistance in human clinical isolates of Salmonella between July 1, 1994, and June 30, 1995. Every tenth nontyphoidal Salmonella isolate received at state public health laboratories in the United States during this period was tested for resistance to 12 antimicrobial agents, including two quinolones, nalidixic acid, and ciprofloxacin. Emerging quinolone resistance was detected; of 4,008 isolates tested, 21 (0.5%) were resistant to nalidixic acid, and one (0.02%) was resistant to ciprofloxacin. Continued surveillance for quinolone-resistant Salmonella is necessary, particularly after the recent approval of a fluoroquinolone for use in animals intended for food in the United States.     

Comparison of enoxacin versus trimethoprim-sulfamethoxazole in the treatment of patients with complicated urinary tract infection

Given the prevalence of complicated urinary tract infection (UTI) and the resistance patterns of common uropathogens, antimicrobial therapy for complicated UTI must be carefully selected. For patients with complicated UTI who can be treated with oral medication, the quinolones or trimethoprim-sulfamethoxazole (TMP-SMX) are reasonable treatment choices. Enoxacin and TMP-SMX were compared for efficacy, safety, and bacteriologic response in this study. A total of 260 patients with complicated UTI were enrolled in a multicenter, open-label, randomized study and received enoxacin or TMP-SMX. Short-term assessments 5 to 9 days posttherapy and long-term assessments 4 to 6 weeks posttherapy included physical and clinical evaluations, laboratory testing, urine cultures, and susceptibility testing. Although enoxacin and TMP-SMX demonstrated comparable short-term efficacy rates, enoxacin exerted a potent, long-term bacteriologic response, particularly against Escherichia coli. Enoxacin therapy achieved a 94.7% long-term eradication rate against E coli compared with a 76.0% eradication rate against this pathogen with TMP-SMX. Most adverse events were mild, and a comparable incidence (approximately 17%) occurred in both treatment groups. These data indicate that enoxacin is an excellent addition to the armamentarium of agents commonly used in the treatment of patients with complicated UTI.     

Y-688, a new quinolone active against quinolone-resistant Staphylococcus aureus: lack of in vivo efficacy in experimental endocarditis

Y-688 is a new fluoroquinolone with increased activity against ciprofloxacin-resistant staphylococci. The MICs of Y-688 and other quinolones were determined for 58 isolates of ciprofloxacin-resistant and methicillin-resistant Staphylococcus aureus (MRSA). The MICs at which 50% and 90% of bacteria were inhibited were >/=128 and >/=128 mg/liter, respectively, for ciprofloxacin, 16 and 32 mg/liter, respectively, for sparfloxacin, and 0.25 and 1 mg/liter, respectively, for Y-688. This new quinolone was further tested in rats with experimental endocarditis due to either of two isolates of ciprofloxacin-resistant MRSA (namely, P8/128 and CR1). Infected animals were treated for 3 days with ciprofloxacin, vancomycin, or Y-688. Antibiotics were administered through a computerized pump to simulate human-like pharmacokinetics in the serum of rats. The anticipated peak and trough levels of Y-688 were 4 and 1 mg/liter at 0.5 and 12 h, respectively. Treatment with ciprofloxacin was ineffective. Vancomycin significantly decreased vegetation bacterial counts for both organisms (P less, similar 0.05). In contrast, Y-688 only marginally decreased vegetation bacterial counts (P greater, similar 0.05). Moreover, several vegetation that failed Y-688 treatment grew staphylococci for which the MICs of the test antibiotic were increased two to eight times. Y-688 also selected for resistance in vitro, and isolates for which the MICs were increased eight times emerged at a frequency of ca. 10(-8). Thus, in spite of its low MIC for ciprofloxacin-resistant MRSA, Y-688 failed in vivo and its use carried the risk of resistance selection. The fact that ciprofloxacin-resistant staphylococci became rapidly resistant to this potent new drug suggests that the treatment of ciprofloxacin-resistant MRSA with new quinolones might be more problematic than expected.     

Antibiotic susceptibility of campylobacter isolates from sewage and poultry abattoir drain water

In this study, the in vitro susceptibility of 209 campylobacter strains to the quinolones nalidixic acid, flumequine, ciprofloxacin, enrofloxacin, and to ampicillin, tetracycline and erythromycin was tested by the disk diffusion method. The strains were isolated from poultry abattoir effluent (DWA) and two sewage purification plants (SPA and SPB). Sewage purification plant SPA received mixed sewage, including that from a poultry abattoir, whereas SPB did not receive sewage from any meat-processing industry. The quinolone resistance of the DWA isolates ranged from 28% for enrofloxacin to 50% for nalidixic acid. The strains isolated from the sewage purification plants were more susceptible to the quinolones with a range of 11-18% quinolone resistance for SPB isolates to 17-33% quinolone resistance for SPA isolates. The susceptibility criteria as recommended by National Committee Clinical Laboratory Standards (USA) cannot readily be employed for campylobacter isolates. This investigation shows that the resistance of campylobacter bacteria is highest in the plant receiving sewage from a poultry slaughterhouse. Monitoring of antibiotic resistance of aquatic Campylobacter spp. is important, as surface waters are recognized as possible sources of infection.     

Bacterial pathogens and their antimicrobial susceptibility in Kumasi, Ghana

Between January, 1994 and June, 1996 a survey of bacterial isolates from clinical specimens and their antimicrobial susceptibility was performed at the Komfo Anokye Teaching Hospital, Microbiology Department, Kumasi, Ghana. A total of 11,380 bacterial isolates were cultured from eight different specimens. The sites of origin were wounds 32.2%, urine 28.1%, ear, nose and throat 3.6%, sputum 2.5% and aspirates 2.5%. Gram-negative bacteria accounted for 7955 (69.9%) isolates, the main species were Escherichia coli 47.1%, Pseudomonas spp. 16.8%, Proteus spp 14.6%, Klebsiella spp 10.2%, Neisseria gonorrhoeae 4.2%, Gram-positive bacteria contributed 3425 ((30.1%) of isolates, with Staphylococcus aureus 54.6% being the most predominant followed by Coagulase negative Staphylococcus 18.1%, Streptococcus pneumoniae 13.7% and Beta-haemolytic streptococci 4.1%. Escherichia coli showed 88% and 82% resistance to ampicillin and cotrimoxazole respectively with 78% being susceptible to gentamicin. Cefuroxime resistance in Gram-negative bacilli was 5%. As much as 30.6% and 21.7% of Streptococcus pneumoniae isolates were resistant to Penicillin and chloramphenicol respectively. Ten per cent of Staphylococcus aureus strains were susceptible to penicillin and 18% were resistant to flucloxacillin.     

Are clinical laboratories in California accurately reporting vancomycin-resistant enterococci?

In order to determine whether hospital-based clinical laboratories conducting active surveillance for vancomycin-resistant enterococci in three San Francisco Bay area counties (San Francisco, Alameda, and Contra Costa counties) were accurately reporting vancomycin resistance, five vancomycin-resistant enterococcal strains and one vancomycin-susceptible beta-lactamase-producing enterococcus were sent to 31 of 32 (97%) laboratories conducting surveillance. Each strain was tested by the laboratory's routine antimicrobial susceptibility testing method. An Enterococcus faecium strain with high-level resistance to vancomycin (MIC, 512 microg/ml) was correctly reported as resistant by 100% of laboratories; an E. faecium strain with moderate-level resistance (MIC, 64 microg/ml) was correctly reported as resistant by 91% of laboratories; two Enterococcus faecalis strains with low-level resistance (MICs, 32 microg/ml) were correctly reported as resistant by 97 and 56% of laboratories, respectively. An Enterococcus gallinarum strain with intrinsic low-level resistance (MIC, 8 microg/ml) was correctly reported as intermediate by 50% of laboratories. A beta-lactamase-producing E. faecalis isolate was correctly identified as susceptible to vancomycin by 100% of laboratories and as resistant to penicillin and ampicillin by 68 and 44% of laboratories, respectively; all 23 (74%) laboratories that tested for beta-lactamase recognized that it was a beta-lactamase producer. This survey indicated that for clinically significant enterococcal isolates, laboratories in the San Francisco Bay area have problems in detecting low- to moderate-level but not high-level vancomycin resistance. Increasing accuracy of detection and prompt reporting of these isolates and investigation of cases are the next steps in the battle for control of the spread of vancomycin resistance.     

Comparison of three commercial MIC systems, E test, fastidious antimicrobial susceptibility panel, and FOX fastidious panel, for confirmation of penicillin and cephalosporin resistance in Streptococcus pneumoniae

The performances of three commercial broth microdilution MIC assays adapted for use with fastidious organisms--the E test (ET), Fastidious Antimicrobial Susceptibility panel (FAS), and FOX Fastidious panel (FOX)--were compared with a MIC using Mueller-Hinton broth with 5% lysed horse blood (MHLHB) to confirm penicillin and cephalosporin resistance in clinical isolates of Streptococcus pneumoniae. Of the isolates screened for penicillin resistance, 5 (12.8%) were categorized as susceptible, 16 (41.0%) were categorized as intermediate, and 18 (46.2%) were categorized as resistant by MHLHB. Only the isolates exhibiting intermediate-to-resistant MICs were included in the comparison. Agreement within +/- 1 log2 dilution was found in 91, 21, and 76% of the ET, FAS, and FOX MICs, respectively, compared with the MHLHB MIC. No very major or major discrepancies occurred with the ET or FOX; however, two very major interpretive errors occurred with the FAS. Agreement between the ET and MHLHB for cefotaxime, ceftriaxone, and cefuroxime was 88, 85, and 100%, respectively. Less than 50% of cephalosporin MICs categorized as > 0.5 microgram/ml by MHLHB were detected by FAS or FOX. Of the methods compared, the ET was the most reliable alternative for susceptibility testing of pneumococci.     

Resistance of bovine and porcine Pasteurella to florfenicol and other antibiotics

The resistance pattern of 221 (89 bovine, 132 porcine) pasteurella strains isolated in 1996 against 16 antibiotics or chemotherapeutics was determined by agar diffusion. Pasteurella haemolytica showed a higher level of resistance compared to Pasteurella multocida; porcine strains were more resistant than bovine strains. Over 90% of porcine Pasteurella multocida were sensible to penicillin G, ampicillin, cephalothin, polymyxin B, enrofloxacin, chloramphenicol and florfenicol. In addition, bovine strains were at least 90% sensible to oxacillin, erythromycin, gentamycin and sulfmethoxazole-trimethoprim. More than 90% of porcine Pasteurella haemolytica were classified as sensible to polymyxin B, enrofloxacin und florfenicol; bovine strains to cephalothin, neomycin und chloramphenicol as well. In 1996, 2 years after the chloramphenicol ban for food rendering animals, only 6.3% of bovine pasteurella strains proved to be resistant against chloramphenicol compared to a 16.27% fraction in 1994. The mean MIC-values of florfenicol against pasteurella spp. were nearly the same in bovine and porcine isolates with 0.53 microgram/ml and 0.52 microgram/ml respectively. Pasteurella haemolytica, however, showed higher MIC-values (0.68 microgram/ml in bovine, 0.70 microgram/ml in porcine isolates) than Pasteurella multocida with 0.47 microgram/ml in bovine and 0.51 microgram/ml in porcine strains. No isolate had a MIC of florfenicol greater than 1.0 microgram/ml, all pasteurella strains were classified sensible to florfenicol.     

Vocim analysis of laryngeal images: is breathiness related to the glottic area?

289 Shigella strains were isolated from children at the paediatrics department of Ankara University. 75% of the isolates were S. sonnei and 24.8% were S. flexneri. Each strain was tested for resistance to 9 antimicrobial agents. 79% of the isolates were resistant to streptomycin (S), 56% to tetracycline (T), 55.7% to trimethoprim-sulfamethoxazole (SXT), 27.7% to ampicillin (Am) and 19.7% to chloramphenicol (C). None of the isolates was resistant to ciprofloxacin, nalidixic acid, cephalothin, ampicillin-sulbactam and ceftriaxone. 56% of the isolates were resistant to 3 or more antimicrobial agents. The most frequent pattern of resistance of S. sonnei and S. flexneri strains was SXT, T, S (39.6%) and Am, SXT, T, S, C (48.6%), respectively (p < 0.0001). These results demonstrate that trimethoprim-sulfamethoxazole should not be used in the treatment of shigellosis.     

Antimicrobial susceptibility patterns of Aeromonas jandaei, A. schubertii, A. trota, and A. veronii biotype veronii

Fifty-six isolates of four Aeromonas species, which have been documented as causative agents of human infections or isolated from human clinical specimens, were subjected to antimicrobial susceptibility testing using a MicroScan WalkAway conventional (overnight incubation) gram-negative panel. The four species tested and the number of isolates of each were as follows: Aeromonas jandaei, 17; A. schubertii, 12; A. trota, 15; and A. veronii biotype veronii, 12. All isolates of A. trota were susceptible to all antimicrobial agents tested, except cefazolin (20% of isolates were resistant) and cefoxitin (13% of isolates were resistant). All isolates of A. schubertii and A. veronii biotype veronii, as well as 88% of A. jandaei isolates, were resistant to ampicillin. Resistance to ampicillin-sulbactam ranged from 25% of A. schubertii strains to 100% of A. veronii biotype veronii strains. Cefazolin resistance ranged from 17% of A. veronii biotype veronii isolates to 59% of A. jandaei isolates. Imipenem resistance was detected in 65% of A. jandaei strains and 67% of A. veronii biotype veronii strains. A. jandaei displayed resistance to piperacillin and ticarcillin in 53 and 71% of the isolates, respectively. A. veronii biotype veronii strains were 100% susceptible to piperacillin and 100% resistant to ticarcillin. These antibiogram data may be useful in establishing the identification of these four species when members of the genus Aeromonas are isolated from human clinical sources.     

The relationship between faecal egg count reduction and the lethal dose 50% in the egg hatch assay and larval development assay

The relationship between resistance detected in the faecal egg count reduction test (FECRT) and the lethal dose 50% (LD50) in the egg hatch assay (EHA) for benzimidazoles (BZs) and a larval development assay (LDA) for BZs, levamisole (LEV) and ivermectin (IVM) was examined on 13 sheep farms and 12 goat farms in Denmark. Out of 10 farms where resistance to BZs was detected according to the FECRT, nine (90%) had LD50 values above 0.5 microM thiabendazole (TBZ) (0.1 microg TBZ/ml) in the EHA, indicating resistance to BZs. However, four out of the 12 isolates susceptible to BZs in the FECRT had LD50 values higher than 0.5 microM TBZ in the EHA. For all isolates examined, LD50 values for TBZ in the LDA were lower than in the EHA. Four out of 11 and five out of 12 farms with worm populations resistant to BZs according to the FECRT and EHA respectively, had LD50 values lower than 0.5 microM TBZ in the LDA. Using the same cut-off point for resistant isolates in the LDA as in the EHA (0.5 microM TBZ), these isolates would be considered susceptible to BZs. All 10 isolates susceptible to BZs according to the FECRT and EHA and two isolates with suspect BZ resistance had LD50 values lower than 0.5 microM TBZ in the LDA. The above results indicated fairly good agreement in the detection of BZ resistance between the FECRT, EHA and the LDA. Groups of farms where resistance to LEV was detected according to the FECRT had higher mean LD50 values compared to those with LEV-susceptible or suspected resistant isolates. However, only four out of 12 farms having isolates resistant to LEV had LD50 values higher than 1.2 microM LEV (0.28 microg LEV/ml) recorded previously for a LEV-susceptible strain of Ostertagia circumcincta. This indicated discrepancies in declaring resistance to LEV between the FECRT and the LDA. Isolates from four farms where resistance to IVM was detected in the FECRT had LD50 values higher than the susceptible isolates. These were 2.5 to 7.5 times higher than those recorded previously for IVM-susceptible strains.     

Desiderata for product labeling of medical expert systems

The ability of seventy clinical laboratories in nine European countries to detect glycopeptide resistance in Gram-positive bacteria was investigated. Results of routine tests were compared with those on the same strains by a reference method in national co-ordinating laboratories. In addition, control strains were tested by some of the participants. Errors in reporting susceptibility of Staphylococcus aureus to teicoplanin and vancomycin and coagulase-negative staphylococci to vancomycin were < 1%. With coagulase-negative staphylococci however, 44 (3.4%) teicoplanin susceptible isolates were reported intermediate and six (0.4%) resistant; 18 (58.1%) of 31 teicoplanin intermediate isolates were reported susceptible and five (16.1%) resistant; and six of nine teicoplanin resistant isolates were reported susceptible and two intermediate. All seven isolates of enterococci intermediate to vancomycin were reported susceptible. Distribution of a known vancomycin intermediate strain of E. gallinarum indicated problems with vancomycin susceptibility testing (44.4% reported susceptible, 32.7% intermediate, 32.1% resistant) and identification (only 34.1% correct) of this organism. Two of 28 teicoplanin resistant enterococci and three of 30 vancomycin resistant isolates were reported susceptible. Among other organisms, one resistant Lactobacillus sp. was reported susceptible to teicoplanin and vancomycin. In reporting teicoplanin susceptible organisms, there were fewer errors with comparative/Stokes methods than with most other methods and more errors with the ATB and Sceptor methods than most other methods. None of the methods used were reliable for testing teicoplanin intermediate and resistant coagulase-negative staphylococci or low-level vancomycin resistant enterococci. Alternative methods, such as breakpoint screening, should be considered for detecting glycopeptide resistance.     

Multidrug-resistant tuberculosis. 2. Mechanisms of drug-resistance in Mycobacterium tuberculosis--genetic mechanisms of drug-resistance

Multidrug-resistant Mycobacterium tuberculosis infection is now world wide health problem. However, according to the recent advances of molecular biological technics, some of the genetic mechanisms of drug-resistance of M. tuberculosis has been uncovered. Generally, drug-resistance of M. tuberculosis was caused by point mutations in chromosomal gene. In isoniazid (INH) resistant M. tuberculosis, mutations and genetic deletions in catalase-peroxidase gene (katG), inhA gene, or alkyl hydroperoxide reductase gene were reported. We also found that about 15% of INH-resistant M. tuberculosis isolates lacked katG gene, and these isolates showed highly resistance to INH with MIC > or = 64 micrograms/ml. On the other hand, mutations and other genetic alterations in RNA polymerase beta subunit gene (rpoB) were the major mechanisms of resistance to rifampicin (RFP) with high frequencies of 90% or more. Our evaluation of the relationship between RFP susceptibility and genetic alteration in rpoB gene also showed that 95% of RFP-resistant M. tuberculosis isolates involved genetic alterations in 69 bp core region of rpoB gene. Moreover, these genetic alterations in rpoB gene were suspected as the resistant mechanism to other rifamycin antituberculosis drugs, such as rifabutin and KRM-1648. In addition, it was reported that point mutations in 16S rRNA gene (rrs) and ribosomal protein S12 gene (rpsL) induced M. tuberculosis as streptomycin (SM) resistant phenotype. We analyzed genetic alternations in rpsL gene of clinically isolates of M. tuberculosis, about 60% of SM resistant isolates were shown point mutation in this gene ant they were all high SM-resistant with MIC > or = 256 micrograms/ml. Furthermore, nicotinamidase (pncA) gene, DNA gyrase A subunit (gyrA) gene, and embB gene were reported as the responsible gene to pyrazinamide-, quinolone- and ethambutol-resistance, respectively. Although all mechanisms of drug-resistance were still unclear, these informations are very useful and helpful for development of rapid diagnosis system of drug-resistant M. tuberculosis.     

High-intensity focused ultrasound (HIFU) in the treatment of benign prostatic hyperplasia (BPH)

The prevalence of antibiotic resistant Escherichia coli isolates from faecal samples from 110 veterinarians with different specialties (predominantly working with cattle, swine, poultry, or small animals or working as a non-practitioner, e.g. in government or industry) was investigated. In 22% and 13% of the veterinarians E. coli isolates showed a high level of resistance to oxytetracycline and ampicillin respectively. A significantly higher percentage of cattle practitioners had a high level of antibiotic resistance against ampicillin than did swine practitioners. Furthermore, a significantly higher percentage of poultry practitioners had a high level of antibiotic resistance against oxytetracycline than did swine practitioners and non-practitioners. A significantly higher percentage of practitioners recently (within last 6 months) used antibiotics for personal intake than did the group of non-practitioners. There was no evidence for a relationship between personal intake of antibiotics and the occurrence of a high level of resistance to ampicillin or oxytetracycline. The prevalence of E. coli isolates, that were resistant to several antibiotics was highest in cattle and poultry practitioners and the lowest in swine practitioners. A possible explanation for the observed differences in high level resistance to oxytetracycline and ampicillin between veterinary specialty groups is a difference in exposure to antibiotics during practice.     

Effects of glycemic control on saliva flow rates and protein composition in non-insulin-dependent diabetes mellitus

Records from patients admitted to the surgical or medical department or examined in the respective outpatient departments in a Kuwaiti district hospital were reviewed retrospectively to discern the demographic characteristics of patients with complicated urinary tract infections (UTI), underlying conditions, pathogens and their antimicrobial susceptibility patterns. Kuwaiti nationals constituted the largest group, followed by Egyptians, which in the population of 225 patients studied comprised 41% and 27%, respectively; 65 of these 225 patients (29%) had urinary stones; 33 of the 92 Kuwaiti patients (36%) had diabetes mellitus; 38 of the 60 Egyptian patients (63%) had urinary stones and 18 had bilharziasis (30%). Pathogens were isolated 353 times from 225 patients. Escherichia coli, Klebsiella pneumoniae, Pseudomonas aeruginosa and several other organisms in those patients with bilharziasis, urinary stones, and especially diabetes mellitus, displayed lower susceptibility frequencies to antimicrobials in comparison with other surgical and medical UTI isolates. Surgical and medical UTI organisms showed an overall higher antimicrobial resistance frequency than did UTI organisms from the maternity department or regional clinics. More than half of the population of Kuwaiti consists of expatriates from different countries. Such a population structure can exhibit peculiarities when health is considered. All this should be taken into consideration while dealing with disease management.     

Unstable atherosclerotic plaque. Pathophysiology and therapeutic guidelines

One hundred fifty clinical isolates of Enterococcus faecalis (88 isolates) and Enterococcus faecium (62 isolates) were tested in vitro for their susceptibility to vancomycin and high-level aminoglycosides (HLA). Remel's Synergy Quad Plates (RSQ) were used as the reference method and compared to Kirby-Bauer disc diffusion test, Vitek GPS-TA card, MicroScan Panel (GP-6), and Etest. Streptomycin susceptibility results for MicroScan GP-6 and RSQ were recorded at 24 and 48 h and all other methods and antibiotics were read at 24 h or less. When compared with the agar screen method, all of the methods demonstrated > 99% agreement. One isolate was falsely sensitive to gentamicin at 24 h, but resistant at 48 h, when tested on both MicroScan and RSQ agar screen. Thirty-nine isolates showed resistance to vancomycin with all methods. These isolates were from three different local hospitals and were identified as E. faecium. Pulse-field gel electrophoresis demonstrated that all of the vancomycin-resistant isolates were derived from the same clone. Of interest is the observation that high-level resistance to aminoglycosides varied between the clonally related isolates.     

Resistance to fluoroquinolones in Escherichia coli isolated from poultry

Quinolone-resistant Escherichia coli strains were isolated from poultry clinical samples in Saudi Arabia. The poultry flocks had been treated with oxolinic acid or flumequine prophylaxis. The measure of the uptake of fluoroquinolones showed that none of the strains had a reduced accumulation of quinolones. The result of complementation with the wild-type E. coli gyrA gene, which restored fluoroquinolone susceptibility, and the isolation of DNA gyrase from six isolates indicated that the resistant strains had an altered DNA gyrase. The minimum effective dose of ciprofloxacin for inhibition of supercoiling catalyzed by the isolated gyrases varied from 0.085 microgram/ml for a susceptible isolate (MIC < 4 micrograms/ml) up to 96 micrograms/ml for the more resistant one (strain 215, MIC > 64 micrograms/ml). For the same two isolates, the minimum effective doses of sparfloxacin varied from 0.17 up to 380 micrograms/ml. The in vitro selection of spontaneous single-step fluoroquinolone-resistant mutants using ciprofloxacin suggested that the more resistant mutants are likely the result of several mutations. These results also show that, as in human medicine, cross-resistance between older quinolones and fluoroquinolones can exist in veterinary isolates and reiterate the need for the prudent use of these drugs.     

Molecular epidemiological analysis of quinolone-resistant Escherichia coli causing bacteremia in neutropenic patients with leukemia in Korea

We analyzed an outbreak of Escherichia coli bacteremia in eight patients with leukemia in a hematology-oncology unit from July to September 1994. The antibiograms and genotypic patterns of the isolates were different, thus suggesting that the outbreak did not originate from a single clone. However, all the isolates were resistant to quinolones, which led us to examine the microbiological records from 1992 to 1994. The incidence of quinolone-resistant E. coli bacteremia in the hematology-oncology unit ranged from 81.8% to 94.6% during this period. We then analyzed 36 more isolates recovered from late 1994 to 1995. Field inversion gel electrophoresis patterns of these isolates were also different. Analysis of the quinolone resistance determining region in gyrA revealed that all the isolates had a double mutation in gyrA. In conclusion, quinolone-resistant E. coli could be an emerging threat to neutropenic patients with leukemia who receive a quinolone prophylactically, and attention must be paid to this trend of resistance.