Comparative in vitro activity of three new quinolone antibiotics against recent clinical isolates

Viral antigen nanoparticles for discriminated and quantitative detection of different subtypes of anti-virus immunoglobulins

The aim of this study is to develop a novel method for the accurate diagnosis of the infection status of viral diseases, which requires discriminated and quantitative detection of different anti-virus immunoglubulin subtypes. Considering hepatitis A as a representative model disease, viral antigen nanoparticles (vAgNPs) were designed and synthesized by genetically presenting hepatitis A virus (HAV) antigens on the surface of human heavy chain ferritin (hFTH) nanoparticles to detect anti-HAV antibodies with discriminating immunoglobulin subtypes M and G (IgM and IgG, respectively). The vAgNPs also display multi-copies of hexa-histidine peptide (H6) on their surface to chemisorb gold ions (Au3+), which is vital for the autonomous generation of quantitatively meaningful detection signals. The quantitative level of anti-HAV IgM or IgG in 30 patient sera was successfully analyzed using the vAgNPs of HAV, which was performed through label-free one-step-immunoassay based on the self-enhancement of optical signals from gold nanoparticles clustered on the viral antigen nanoparticles. The diagnostic performance was compared with that of enzyme-linked immunosorbent assay (ELISA), which did not enable accurate quantitative assay due to the poor linearity between the antibody concentration and detection signal. Furthermore, these vAgNP-based immunoassays did not produce any false negative/positive signals, indicating 100% sensitivity and 100% specificity.

Antibiotic resistance of urinary pathogens isolated from patients attending The Toronto Hospital between 1986 and 1990

A study was carried out on 1523 urinary isolates obtained at The Toronto Hospital, Canada's largest tertiary care establishment, over three 1-month periods in 1986, 1987 and 1990. Escherichia coli was the most frequently isolated organism, with Enterococcus spp. the second most common isolate in 1986 and 1987, and Streptococcus spp. in 1990. Pseudomonas aeruginosa isolates were found to be resistant to many of the antimicrobial agents tested. Resistance patterns were found to commonly prescribed ampicillin, co-trimoxazole and, to some extent, the new fluoroquinolones, ciprofloxacin and norfloxacin. These results are relevant to the treatment and management of urinary tract infections in patients attending a tertiary care hospital.

Comparative in-vitro activity of fourteen antibiotics against clinical isolates of enterococci

The in-vitro antibacterial activities of fourteen antimicrobial agents, including ampicillin, amikacin, Augmentin, ceftazidime, cefotaxime, ceftriaxone, ciprofloxacin, erythromycin, gentamicin, penicillin G, piperacillin, rifampicin, streptomycin and vancomycin, were compared against 195 enterococcal strains isolated from clinical specimens received at the King Abdulaziz University Hospital in Saudi Arabia. The antibacterial susceptibility was determined by the minimal inhibitory concentration (MIC) using an agar dilution method. Ampicillin, Augmentin and vancomycin exhibited the greatest activity, inhibiting 90% of the tested strains (MIC90) at 2 micrograms/ml, followed by penicillin G and piperacillin with MIC90 of 4 micrograms/ml. Erythromycin, third generation cephalosporins, aminoglycosides and rifampicin, on the other hand, had poor activity against enterococci with MIC90s well above the obtainable serum concentrations. The clinical implications of resistance to aminoglycosides and the alternative antimicrobial therapy in serious enterococcal infections are discussed in the text.

Rubella vaccination

Rubella vaccination programmes aim to prevent congenital rubella infections. Previously differing programmes have now converged according to the following principle: First vaccination should be given at the age of 15 months (together with measles and mumps vaccine) to both boys and girls, in order to diminish the circulation of the wild virus. Teenage girls require (re-)vaccination to ensure their immunity. Also non-immune women have to be identified and vaccinated before they become pregnant. A low acceptance rate increases the risk of infection of pregnant women, independent of the vaccination omitted. As a rule natural and vaccine-induced immunity prevents congenital rubella infections. These infections are exceedingly rare in children born to immune mothers, and are always caused by the wild virus. This minimal risk will disappear only with the eradication of rubella virus, still a distant goal in countries offering vaccination only on a voluntary basis.

Ciprofloxacin: chemistry, mechanism of action, resistance, antimicrobial spectrum, pharmacokinetics, clinical trials, and adverse reactions

Ciprofloxacin, considered a benchmark when comparing new fluoroquinolones, shares with these agents a common mechanism of action: inhibition of DNA gyrase. While ciprofloxacin demonstrated a fairly good activity against gram-positive bacteria, it is against gram-negative organisms that it proved to be more potent than other fluoroquinolones. It is the most active quinolone against Pseudomonas aeruginosa, with MIC90s on the order of 0.5 micrograms/ml. When given orally, ciprofloxacin exhibited 70% bioavailability and attained peak serum levels ranging between 1.5 and 2.9 micrograms/ml after a single 500-mg dose. Nineteen percent of an oral dose was excreted as metabolites in both urine and feces. In most cases, body fluids and tissue concentrations equaled or exceeded those in concurrent serum samples. In clinical trials, oral and intravenous ciprofloxacin yielded similar clinical and bacteriologic results compared to standard therapy in a wide array of systemic infections, including lower and upper urinary tract infections; gonococcal urethritis; skin, skin structure, and bone infections; and respiratory tract and gastrointestinal tract infections. Major benefits with the oral form of this quinolone are expected in chronic pyelonephritis and bone infections, and in pulmonary exacerbations in patients with cystic fibrosis. Emergence of ciprofloxacin-resistant microorganisms has been noted in clinical practice, primarily Pseudomonas aeruginosa and Staphylococcus aureus. The most frequent side effects are related to the gastrointestinal tract; but attention should be given to adverse central nervous system effects.

Management of pregnant women with contagious infections at delivery

Since 1970 pregnant women with contagious infections in the country of Stockholm have been delivered at the Danderyd Hospital, the only hospital in the area which has departments of obstetrics and pediatrics as well as infectious diseases. This paper presents data from a prospective study carried out during a period of 10 years (1975-1984). The study includes 303 women and their newborns who for various reasons were transferred to the Department of Infectious Diseases (DID) before or after delivery. A comprehensive microbiological investigation was made in order to establish an etiological diagnosis in all women included in the study. A possible transmission of the infection from the mother to her fetus/child before or after delivery was also investigated. Only 0.17% of the pregnant women in the area needed care at the DID at delivery or in the puerperal period. 9% of the deliveries occurred at another hospital, 32% at the DID and the remaining at the obstetrical department, Danderyd Hospital. The rate of complications, including cesarean sections, was 12%. Of the 165 women suffering from an infectious disease at the time of delivery, 40% had a verified viral disease--in most cases varicella or mumps, 28% had a bacterial infection and for 32% no etiology of the disease could be established. The study population also includes women suspected either to be incubated with a contagious disease or to be carriers of infectious agents, as well as healthy mothers whose newborns were expected to be carriers of infectious agents such as rubella and varicella. None of the women died during the study period but 5 were seriously ill and 3 needed intensive care. The rate of stillbirths was the same as reported among all births in the country of Stockholm but the perinatal mortality rate was significantly higher (see also a following article, ref. 27). Our routines prove the necessity to take special care of pregnant women carrying a contagious infectious agent at term.

In vitro selection of Escherichia coli mutants with decreased susceptibility to norfloxacin

In 10 clinical isolates of Escherichia coli the frequency of spontaneous mutation to high levels of resistance to nalidixic acid was greater than 300-fold higher than that to norfloxacin. Norfloxacin resistant mutants could not be detected (mutation frequency: less than 10(-12). However, nalidixic acid resistant mutants of E. coli developed decreased susceptibility to norfloxacin at a rate of approximately 10(-9). Mutants with decreased susceptibility to norfloxacin could also be obtained when the same clinical isolates of E. coli were exposed to norfloxacin in 2 steps. However, mutants with MIC values greater than 8 micrograms/ml for norfloxacin were never obtained even after repeated exposure. Widespread use of cinoxacin or nalidixic acid may select resistant strains and reduce the efficacy of norfloxacin and other 4-quinolones.

Ciprofloxacin

Ciprofloxacin is a new fluorinated quinolone antibiotic with high activity against a wide spectrum of gram-positive and gram-negative bacteria, including methicillin-resistant Staphylococcus aureus, Enterobacteriaceae, and Pseudomonas aeruginosa. Clinical trials using the oral preparation of ciprofloxacin have demonstrated its effectiveness in a wide variety of infections. In addition, extensive clinical trials with the intravenous preparation are underway. In vitro and in vivo studies with ciprofloxacin have reported the incidence of resistant organisms to be very low. In addition, the incidence of ciprofloxacin-related side effects throughout its clinical trials has been minimal. Most reports of side effects have been related to the gastrointestinal tract, such as nausea or vomiting. The incidence of adverse experiences in worldwide clinical trials has been reported to be approximately 6.4 percent.

4-Quinolone drugs affect cell cycle progression and function of human lymphocytes in vitro

Most antibacterial agents do not affect human lymphocyte function, but a few are inhibitory. In contrast, a pronounced increase in the incorporation of [3H]thymidine in the presence of 4-quinolones was observed in these studies. The uptake of [3H]thymidine into DNA (trichloroacetic acid precipitable) was significantly increased in phytohemagglutinin-stimulated human lymphocytes when they were exposed to eight new 4-quinolone derivatives, ciprofloxacin, norfloxacin, ofloxacin, A-56619, A-56620, amifloxacin, enoxacin, and pefloxacin, at 1.6 to 6.25 micrograms/ml for 5 days. Four less antibacterially active 4-quinolones (nalidixic acid, cinoxacin, flumequine, and pipemidic acid) stimulated [3H]thymidine incorporation only at higher concentrations or not at all. Kinetic studies showed that incorporation of [3H]thymidine was not affected or slightly inhibited by ciprofloxacin 2 days after phytohemagglutinin stimulation but was increased on days 3 to 6. The total incorporation of [3H]thymidine from day 1 to day 6 after phytohemagglutinin stimulation was increased by 42 to 45% at 5 to 20 micrograms of ciprofloxacin per ml. Increased [3H]thymidine incorporation was also seen when human lymphocytes were stimulated with mitogens other than phytohemagglutinin. Ciprofloxacin added at the start of the culture had a more pronounced effect on [3H]thymidine incorporation than when added later. In spite of the apparent increase in DNA synthesis, lymphocyte growth was inhibited by 20 micrograms of ciprofloxacin per ml, and cell cycle analysis showed that ciprofloxacin inhibited progression through the cell cycle. In addition, immunoglobulin secretion by human lymphocytes stimulated by pokeweed mitogen for Epstein-Barr virus was inhibited by approximately 50% at 5 micrograms of ciprofloxacin per ml. These results suggest that the 4-quinolone drugs may also affect eucaryotic cell function in vitro, but additional studies are needed to establish an in vivo relevance.

Effects of ciprofloxacin on eucaryotic pyrimidine nucleotide biosynthesis and cell growth

Several of the new 4-quinolones significantly increase the incorporation of [3H]thymidine into the DNA of mitogen-stimulated human lymphocytes. This study suggests that ciprofloxacin inhibits de novo pyrimidine biosynthesis, thereby resulting in a compensatory increase in the uptake of pyrimidine precursors through salvage pathways, and that additional effects may affect eucaryotic cell growth. Incorporation of deoxyuridine, uridine, and orotic acid as well as thymidine was increased in the presence of ciprofloxacin, one of the antibacterially most active of the new 4-quinolones. In contrast, the uptake was decreased in very high concentrations of the drug. Culture in HAT (hypoxanthine, aminopterine, thymidine) medium, which blocks de novo thymidylate synthesis, abrogated the increase in [3H]thymidine incorporation induced by ciprofloxacin. Ciprofloxacin also failed to increase the uptake of [14C]hypoxanthine or leucine, indicating a selective effect on pyrimidine and not on purine nucleotide biosynthesis. N-(Phosphonacetyl)-L-aspartate, an inhibitor of pyrimidine nucleotide biosynthesis, also increased [3H]thymidine incorporation in phytohemagglutinin-stimulated lymphocytes in a fashion similar to ciprofloxacin. The growth of several cell lines was partially inhibited by ciprofloxacin at 20 micrograms/ml and completely inhibited at 80 to 160 micrograms/ml. Growth inhibition by ciprofloxacin could not be restored by the addition of uridine to the medium. Chromosome breaks, gene amplification, or other genetic alterations could not be detected in human lymphocytes incubated with up to 25 micrograms of ciprofloxacin per ml.

Identification of Streptococcus faecalis and Streptococcus faecium and susceptibility studies with newly developed antimicrobial agents

Identification and susceptibility studies were performed on 301 blood and urine Streptococcus faecalis and Streptococcus faecium isolates. Strep Trio-Tubes S4, S5, and S3 (Carr-Scarborough Microbiologicals, Inc.) were compared with conventional methods for accuracy and rapidity. Of 282 isolates identified as S. faecalis, 98% were identified by species in 4 h with Trio-Tubes; the same percentage of isolates analyzed by conventional methods were identified in 24 h. All 14 S. faecium isolates (approximately 5% of the total number of isolates) were identified by Trio-Tubes in 24 h. In vitro MIC susceptibility testing of the isolates was performed by the Dynatech 2000 microdilution technique (Dynatech Laboratories, Inc.). Several newly developed antimicrobial agents, including imipenem (a carbapenem) and some of the quinolone drugs, i.e., CI-934, ciprofloxacin, A-56619, A-56620, amifloxacin, norfloxacin, and enoxacin, were tested, as were ampicillin, erythromycin, and vancomycin. Both ampicillin and vancomycin showed good activity against S. faecalis, with MICs for 90% of isolates tested (MIC90S) of 1 and 2 micrograms/ml, respectively; with S. faecium, ampicillin exhibited an MIC90 of 16 micrograms/ml and vancomycin exhibited an MIC90 of 2 micrograms/ml. Of the newer antimicrobial agents, imipenem and CI-934 exhibited the greatest activity against S. faecalis strains, with MIC90S of 2 and 0.5 micrograms/ml, respectively. MBCs against the isolates were determined with CI-934, with 90% of S. faecalis strains showing MBCs of 1 microgram/ml or less.

Ofloxacin. A review of its antibacterial activity, pharmacokinetic properties and therapeutic use

Ofloxacin is one of a new generation of fluorinated quinolones structurally related to nalidixic acid. It is an orally administered broad spectrum antibacterial drug active against most Gram-negative bacteria, many Gram-positive bacteria and some anaerobes. Ciprofloxacin is the only other quinolone with superior in vitro antibacterial activity. However, the pharmacokinetic profile of ofloxacin is superior to that of ciprofloxacin, with more rapid absorption and a peak serum concentration several times higher. Moreover, ofloxacin achieves high concentrations in most tissues and body fluids. The results of clinical trials with ofloxacin have confirmed the potential for use in a wide range of infections, which was indicated by its in vitro antibacterial and pharmacokinetic profiles. It has proven effective against a high percentage of infections caused by Gram-negative organisms, slightly less effective against Gram-positive infections, and effective against some anaerobic infections. Clinical efficacy has also been confirmed in a variety of systemic infections as well as in acute and chronic urinary tract infections, and ofloxacin has generally appeared to be at least as effective as alternative orally administered antibacterial drugs. Ofloxacin is well tolerated and, although experience with the drug in clinical practice to date is limited, bacterial resistance does not appear to develop readily. Thus, ofloxacin is an orally active drug which offers a valuable alternative to other broad spectrum antibacterial drugs.

Review of the 4-quinolones

Improvements in antimicrobial activity and pharmacokinetics have moved the 4-quinolones into the forefront of antibiotic research. The 4-quinolones are analogues of nalidixic acid, and there are presently at least six agents in this group under investigation in the United States. It is difficult to generalize their clinical usefulness, since these agents exhibit different pharmacokinetic profiles, antimicrobial activity (with varied minimum inhibitory concentrations among similar organisms), and dosage regimens. The 4-quinolones are potential therapeutic alternatives for infections caused by a variety of organisms. They include: Neisseria gonorrhoeae; Pseudomonas aeruginosa; Haemophilus influenzae; Staphylococcus aureus; common enteric pathogens (salmonella, shigella, campylobacter, etc); and intracellular bacteria (legionella, chlamydia, mycobacteria, etc). Clinical efficacy has been demonstrated in urinary tract infections, respiratory tract infections, and sexually transmitted diseases. Future studies will undoubtedly demonstrate effectiveness in numerous additional infectious processes. The purpose of this article is to compare the 4-quinolones in regards to pharmacokinetics and spectrum of activity and review the clinical studies involving these agents.

In vitro and in vivo activity of ciprofloxacin against enterococci isolated from patients with infective endocarditis

In vitro activity of ciprofloxacin against 27 strains of enterococci was inoculum dependent. Using inocula of 10(5) to 10(6) or 10(7) to 10(8) CFU of enterococci per ml, the MICs for 50 and 90% of strains tested increased from 1 to greater than or equal to 128 micrograms of ciprofloxacin per ml with the higher inoculum compared with the lower inoculum. The MBC for 50% of strains tested increased from 2 to greater than 128 micrograms/ml and the MBC for 90% of strains tested increased from 8 to greater than 128 micrograms of ciprofloxacin per ml with the lower and higher inocula, respectively. The combination of penicillin-gentamicin was more effective in vitro than the combination of ciprofloxacin-gentamicin against the low or high inoculum of enterococci. Using two strains of enterococci, we studied the efficacy of ciprofloxacin in the treatment of enterococcal experimental endocarditis in rabbits. Ciprofloxacin used alone or combined with gentamicin was significantly less effective (P less than 0.01) than procaine penicillin alone or procaine penicillin combined with gentamicin for the treatment of enterococcal experimental endocarditis. The combination of ciprofloxacin-procaine penicillin was not a more effective therapy than procaine penicillin alone.

Controlled trial of a short and a prolonged course with ciprofloxacin in patients undergoing transurethral prostatic surgery

The efficacy of a short (Group I) and a prolonged (Group II) course with ciprofloxacin was assessed in patients undergoing transurethral prostatic resection for benign hyperplasia or cancer of the prostate and compared with that of controls without antibiotic (Group III). Both regiments significantly reduced the frequency of postoperative bacteriuria (p less than 0.01) and of severe infectious complications (p = 0.004) as compared to the controls. Both regimens were equally effective in preventing perioperative and postoperative acquisition of bacteriuria in patients without bacteriuria at surgery. In patients with bacteriuria before surgery, bacteriuria was found postoperatively in 35% in Group I and 10% in Group II (p = 0.012), but in 82% of the patients in Group III. Ciprofloxacin inhibited all but 7 of 176 bacterial strains at an MIC of less than or equal to 1 microgram/ml. Given orally ciprofloxacin is a valuable alternative antimicrobial for use in conjunction with transurethral prostatic resection. A short course is sufficient for prophylaxis, and adequate therapy is achieved with a prolonged regimen.

Failure of a single dose of 100 mg ofloxacin in lower urinary tract infections in females

A single dose of 100 mg ofloxacin was compared with a multiple dose of cotrimoxazole in lower urinary tract infections in 137 women. The elimination rate was significantly lower in the single dose treated group of patients in spite of all strains being in vitro susceptible in this group.

Norfloxacin versus co-trimoxazole for treatment of urinary tract infections in adults: microbiological results of a coordinated multicentre study

In a prospective, coordinated, double-blind multicentre trial, outpatients with urinary tract infections were randomized to 7 days b.i.d. treatment with norfloxacin 200 mg or 400 mg or trimethoprim/sulfamethoxazole. The most prevalent species was Escherichia coli (76.6%) followed by Staphylococcus saprophyticus (14.1%), the latter of which showed a marked seasonal variation with peak incidence during late summer. Minimum inhibitory concentrations (MICs) of 11 antibiotics for 651 pre-treatment bacterial strains were studied. Norfloxacin was found to be active against all isolates with MICs less than or equal to mg/l for gram-negative and less than or equal to 8 mg/l for gram-positive isolates. Reduced susceptibility to norfloxacin was seen in 2 strains of E. coli and 1 of Klebsiella pneumoniae from patients with persisting or relapsing infections following treatment with norfloxacin 400 mg b.i.d. Of other antibiotics tested, ampicillin, cephalothin and sulfamethoxazole were found to have poor activity against many gram-negative isolates while nalidixic acid and mecillinam lacked activity against all gram-positives. Cefotaxime, gentamicin, trimethoprim and trimethoprim/sulfamethoxazole were generally highly active against the isolated bacterial strains.

In vitro susceptibility of aerobic gram-negative blood culture isolates to oxolinic acid, norfloxacin, ciprofloxacin, enoxacin, pefloxacin, ofloxacin and oxo-enoxacin

100 gram-negative strains isolated from blood cultures were selected for the evaluation of the in vitro activity of oxolinic acid, norfloxacin, ciprofloxacin, enoxacin, pefloxacin, ofloxacin and oxo-enoxacin. Ciprofloxacin showed the highest intrinsic activity. Oxo-enoxacin, the major metabolite of enoxacin, was 10-15-fold less active than enoxacin. Against Enterobacteriaceae and Vibrionaceae, all fluorinated quinolones except norfloxacin were equally effective, while against non-fermenters, ciprofloxacin and ofloxacin demonstrated greater activity than the others. Resistance to oxolinic acid had a detrimental effect on susceptibility to the new fluorinated quinolones.

Quinolones affect thymidine incorporation into the DNA of human lymphocytes

The incorporation of [3H]thymidine into DNA was increased in phytohemagglutinin-stimulated human lymphocytes exposed to four of the new quinolone derivatives (ciprofloxacin, norfloxacin, ofloxacin, and A 56620) at concentrations achievable in clinical situations. However, proliferation of phytohemagglutinin-stimulated lymphocytes was not influenced by ciprofloxacin at concentrations of 0.5 to 10 micrograms/ml.

Effect of ciprofloxacin on phagocytosis

Certain aspects of the relationship between host defence mechanisms and the new quinoline derivative ciprofloxacin in comparison to norfloxacin and ofloxacin were studied. Ciprofloxacin did not affect chemotaxis of human polymorphonuclear leucocytes in agarose. In leucocytes exposed to ciprofloxacin, norfloxacin and ofloxacin neither the chemiluminescent response to opsonized zymosan and formyl-methionyl-leucyl-phenylalanine nor the phagocytic or bactericidal activity was affected. However, killing of Staphylococcus aureus by human polymorphonuclear leucocytes exposed to subinhibitory concentrations of ciprofloxacin was enhanced. The results show that the quinolines tested do not directly influence phagocytic cells, but a subinhibitory concentration can make bacteria more susceptible to phagocytosis and killing.