Mode of antibacterial action of cefprozil, a new cephalosporin, on Escherichia coli, Serratia marcescens and Morganella morganii

The mode of antibacterial action of cefprozil (CFPZ, BMY-28100), a newly developed cephalosporin, was investigated using Escherichia coli K12, Serratia marcescens IFO 12648 and Morganella morganii IFO 3848 as test organisms, in comparison with the action of cefaclor (CCL). The minimum inhibitory concentrations (MICs) of CFPZ for these organisms were 1.56, 800 and 25 micrograms/ml, whereas those of CCL were 1.56, 800 and 100 micrograms/ml, respectively. The addition of a subinhibitory concentration (1/4 MIC) of ethylenediaminetetraacetic acid (EDTA), which damages the permeability barrier of the outer membrane, markedly reduced the MICs of CFPZ for E. coli and S. marcescens, compared with those of CCL, whereas the MICs of both antibiotics for M. morganii were hardly affected by the presence of EDTA. CFPZ was more stable to beta-lactamase activities from these organisms than CCL. The cross-linking reactions of peptidoglycan synthesis catalyzed by the ether-treated cells from these organisms were inhibited by a lower concentration of CFPZ than of CCL.

[Antimicrobial susceptibilities of clinical isolates of Morganella-proteus-providencia group of bacteria]

We examined in vitro susceptibilities of 3,109 isolates belonging to 5 species of Proteeae to 2 penicillins, 5 cephems and 2 aminoglycosides. The isolates were collected from 69 hospital laboratories throughout Japan between 1986 and 1988. Minimal inhibitory concentrations were determined using the agar dilution method with inoculation of 10(8) cells/ml of bacteria. Proteus mirabilis had marked susceptibilities to the penicillins and cephems tested. Proteus vulgaris and Morganella morganii were similar in their susceptibilities to ampicillin (ABPC), piperacillin (PIPC), cefazolin (CEZ), cefotiam (CTM), latamoxef, gentamicin (GM) and netilmicin (NTL), but M. morganii was slightly more resistant to cefmetazole and ceftizoxime (CZX) than P. vulgaris. Providencia rettgeri also had a susceptibility pattern similar to that of P. vulgaris, except that P. rettgeri showed higher resistances to CZX, GM and NTL. Providencia stuartii had a very similar susceptibility pattern to P. rettgeri, but P. stuartii was much more resistant to GM and NTL than the latter. Some major differences on susceptibilities were clearly evident among the 5 species of Proteeae tested. Notable species-specific differences included higher susceptibilities of P. mirabilis to ABPC, PIPC, CEZ and CTM than others and stronger resistances of P. rettgeri and P. stuartii to GM and NTL.

[In vitro sensitivity of gram-negative bacteria isolated from urinary tract infections to various antibiotics]

This study was done on the outpatients and hospitalized patients who were suffering from urinary tract infections in Türkiye Yüksek Ihtisas Hospital. 500 positive cultures were evaluated. E. coli was the predominant organism and it is followed by Klebsiella and Coliform bacteria. The sensitivity of the isolated bacteria were tested against various antibiotic discs using disc diffusion method. The sensitivity of the bacteria to the used antibiotics were as follows: Ceftazidime 96%, ofloxacin 95.6%, piperacillin 56.4%, amoxycillin + clavulanic acid 81.2%, amikacin 82.2%.

Enhancement of in-vitro activity of ofloxacin and gentamicin by rat serum

Normal rat serum shows antibacterial activity because of the presence of endogenous substances. The aim of this research was to study some aspects of the interaction between this biological fluid and some antibiotics, in order to demonstrate possible synergistic activity. Serum is able to lower the minimum inhibitory concentration of gentamicin and ofloxacin against some Gram-negative microorganisms. This can be explained by the presence of lysozyme, antibodies, beta-lysin and other complementary factors that are able to cooperate with these antibiotics.

[Study on new quinolone-resistant strains isolated from urine--annual changes of its frequency and the relation to drug volume]

There is concerned that the new quinolone-resistant strains have increased along with its widespread usage. We analysed the annual changes in frequency of ofloxacin-resistant strains isolated from urine in the past four years at two different types of hospitals, department of urology in Sapporo Medical College and Muroran City Hospital, since the usage of these agents seem to be related to the annual changes of the frequencies. The results were summarised as follows: 1) In the two hospitals, drug volume of the new quinolones had been increased, in particular, the past six years from 1984. 2) The annual changes in frequency of ofloxacin-resistant Staphylococcus aureus have been increasing from 0 to 41.2 percent in Sapporo Medical College and 16.7 to 96.7 percent in Muroran City Hospital. The frequency of ofloxacin-resistant Pseudomonas aeruginosa also have been increasing from 24 to 66.7 percent in Sapporo Medical College and 37.5 to 81.8 percent in Muroran City Hospital. 3) The frequency of ofloxacin-resistant indole positive Proteus spp. and Serratia marcescens for four years at Sapporo Medical College (indole positive Proteus spp.: 0-1.8 percent, Serratia marcescens: 10-43 percent) was very different from that at Muroran City Hospital (indole positive Proteus spp.: 65-82 percent, Serratia marcescens: 71-100 percent). The difference seems to be caused by the hospital acquired infection.

Antimicrobial activity and beta-lactamase stability of BMY-28232, parent compound of an oral cephalosporin

BMY-28232, an aminothiazolyl imino methoxy cephalosporin which is available as an orally absorbed acetoxyethyl ester, inhibited strains of methicillin-susceptible Staphylococcus aureus, hemolytic streptococci, Streptococcus pneumoniae, Escherichia coli, Klebsiella species, and many strains of Proteus and Providencia stuartii at concentrations less than 1 microgram/ml, including isolates resistant to cephalexin and cefaclor. It had activity similar to that of cefixime, but was more active against methicillin-susceptible staphylococci. BMY-28232 was a poor substrate for beta-lactamases but was destroyed by the new TEM-3 enzyme, and had less activity against Enterobacter species, Citrobacter freundii, and Proteus vulgaris isolates. Methicillin-resistant staphylococci, Pseudomonas species, enterococci, Listeria monocytogenes, Corynebacterium jeikeium, Bacteroides fragilus and some strains of Clostridium species were resistant to BMY-28232.

[Susceptibilities of uropathogenic bacteria to ampicillin, cefazolin, cefmetazole and gentamicin. Nine-year survey of changing patterns of susceptibilities]

We analyzed antibiotic susceptibilities of urinary isolates of Escherichia coli, Klebsiella spp., Proteus mirabilis, and Indole (+) Proteus group to ampicillin (ABPC), cefazolin (CEZ), cefmetazole (CMZ) and gentamicin (GM) in 69 laboratories in 1988 and also studied changing patterns of susceptibilities from 1980 to 1988. Minimal inhibitory concentrations were determined using the agar dilution method (MUELLER-HINTON agar, BBL) with inoculation of 10(6) cfu/ml of bacteria. Ninety to 99% of the strains of E. coli, Klebsiella spp. and P. mirabilis were inhibited at a concentration of 6.25 micrograms/ml of CEZ and CMZ and of 1.56 micrograms/ml of GM. Approximately 80% of the strains of Indole (+) Proteus group were inhibited at concentrations of 6.25 micrograms/ml of CMZ and of 1.56 micrograms/ml of GM. However, resistance to ABPC and CEZ was high, with 83% and 81% of the strains being not inhibited at a concentration of 50 micrograms/ml of ABPC and CEZ, respectively. No significant changes in susceptibilities of the 4 bacteria to the above 4 antibiotics were observed over the 9 year period. No increase was found in the incidence of the resistant strains of the 4 bacteria to CMZ and GM, nor of E. coli and Klebsiella spp. to CEZ.

Effect of 1% mandelic acid as a bladder irrigation fluid in patients with in-dwelling catheters

The effect of 1% mandelic acid bladder washouts on 40 patients who were using in-dwelling catheters was studied. The procedure appeared to benefit those colonised with Pseudomonas species but not those colonised with Proteus species. The subject of bladder irrigation is briefly reviewed.

[Comparison of bacteriostatic ability of oleum of Perilla frutescens (L.) Britt., Cinnamomum cassia Presl and Nipagin A]

A comparison of bacteriostatic ability has been carried out among oleum of Perilla frutescens and Cinnamomum cassia, benzoic acid and nipagin A. The result shows that the inhibiting effect of Perilla frutescens and Cinnamomum cassia on microorganisms inoculated and spontaneously contaminated is similar to or obviously superior to nipagin A and benzoic acid.

Synthesis and structure-activity relationships of new 7-[3-(fluoromethyl)piperazinyl]- and -(fluorohomopiperazinyl)quinolone antibacterials

Some novel 6-fluoro-7-substituted-1,4-dihydro-4-oxoquinoline-3-carboxylic acids have been prepared. At the N-1 position "standard" substitution was employed with the ethyl, cyclopropyl, and p-fluorophenyl groups being used. At C-7 the introduction of some novel piperazines was made. Most notably, 2-(fluoromethyl)piperazine (10) and hexahydro-6-fluoro-1H-1,4-diazepine (16, fluorohomopiperazine) at the quinolone C-7 position produced products with similar in vitro antibacterial activity as the ciprofloxacin reference. The in vivo efficacy of 1-cyclopropyl-6-fluoro-7-[3-(fluoromethyl)piperazinyl]-1,4-dihydro-4- oxoquinoline-3-carboxylic acid (20) was excellent with better oral absorption than ciprofloxacin (2).

[Susceptibility of clinically-isolated problem pathogenic bacteria to broad spectrum antibiotics]

The action of broad-spectrum antibiotics investigated by disc diffusion method on 636 problem bacteria such as S. aureus, Enterobacter, Klebsiella, Pseudomonas, E. coli, Proteus that isolated from various clinical specimens. The highest and lowest ratio of susceptibility were as follows: S. aureus were found sensitive 90% to Netilmicin, 27% to Piperacillin, Enterobacter species 78% to Netilmicin, 25% to Piperacillin, Klebsiella 69% to Amikacin, 20% to Piperacillin, Pseudomonas 66% to Amikacin, 5% to Amoxicillin-Clavulanic acid, E.coli 68% to Netilmicin and Ceftriaxone, 32% to Piperacillin, Proteus 70% to Netilmicin, 43% to Piperacillin, S.epidermidis 90% to Amoxicillin-Clavulanic acid, 60% to Piperacillin.

Comparison of ozone and formaldehyde as poultry hatchery disinfectants

Ozone and formaldehyde were compared as poultry hatchery disinfectants in a poultry setter, and evaluated for effectiveness. Escherichia coli, Pseudomonas fluorescens, Salmonella typhimurium, and Proteus spp. were inoculated onto open petri plates and exposed to ozone or onto filter paper strips and exposed to ozone or formaldehyde in a poultry setter. Ozone (1.41 to 1.68% by weight) resulted in significant bacterial reductions of greater than 4 log10 on the open plates and greater than 3 log10 on filter paper strips, whereas formaldehyde (triple strength) resulted in greater than 7 log10 reduction on filter paper strips. Ozone was similarly lethal to organisms on filter paper strips at 90% relative humidity (RH) and 13.9 C, and at 50% RH and 37.7 C. Although under the conditions of this study formaldehyde (triple strength) was more lethal than ozone, ozone killed greater than 99.9% of the starting microbial populations. In the event that formaldehyde can no longer be used in the hatchery, an effective alternative may be ozone.

[Sensitivity to antibiotics of bacterial strains isolated from clinical specimens during the years 1985-1986]

Sensitivity of 312 strains of staphylococci, 386 strains of streptococci and 1193 strains of aerobic gram-negative bacilli to the selected antibiotics was tested. These strains were isolated from the clinical material at the Clinical Hospital No. 1 in Warsaw within 1985-1986. Staphylococci were sensitive to pristinamycin, cefazolin, fusidic acid, oxacillin, and clindamycin. In 1986, a decrease in the number of strains sensitive to these antibiotics, except cefazolin, was seen. In case of streptococci the most active proved chloramphenicol and gentamicin but a significant decrease in the percentage of sensitive strains was also noted in 1986. The highest number of gram-negative bacilli was sensitive to amikacin, colistin, nalidixic acid, pipemidic acid, and gentamicin. In 1986, a decrease in the percentage of sensitive strains was noted. Amikacin and colistin were the most active against Pseudomonas spp. while amikacin and nalidixic and pipemidic acids--against Proteus spp. Comparison of the results with those obtained in 1981-1984 has shown that the sensitivity of staphylococci changed the most significantly and this change was unfavourable. Gentamicin and amikacin remained the most active against gram-negative bacilli while amikacin and colimycin against Pseudomonas spp. In case of anaerobes the majority of strains was sensitive to chloramphenicol, tetracycline and clindamycin. Metronidazole was active against high percentage of Clostridium spp. and all gram-negative bacilli while the percentage of gram-positive bacilli and cocci was sensitive to metronidazole.

Biocidal activity of ozone versus formaldehyde against poultry pathogens inoculated in a prototype setter

Ozone was evaluated as an alternative hatchery disinfectant to replace formaldehyde in the event that the Environmental Protection Agency regulates the use of formaldehyde under the Toxic Substances Control Act. Cultures of Staphylococcus, Streptococcus, and Bacillus species previously isolated from poultry hatcheries and selected culture collections of Escherichia coli, Pseudomonas fluorescences, Salmonella typhimurium, Proteus species, and Aspergillus fumigatus were spread-plated on open petri plates and independently fumigated with ozone or formaldehyde in a prototype laboratory poultry setter. Ozone (1.52% to 1.65% by weight) resulted in bacterial reductions of greater than 4 to 7 log10 and fungal reductions of greater than 4 log10, whereas formaldehyde achieved reductions of greater than 7 log10 and greater than 5 log10, respectively, after 8 min of exposure to either disinfectant. Potential mutagenic effects were observed in ozonated E. coli colonies resulting in decreased superoxide dismutase activity and increased catalase activity when compared with nonozonated control colonies. In this study ozone reduced microorganism counts but not as much as formaldehyde. Ozone may be used as a disinfectant against selected microorganisms, although further testing under actual hatchery conditions is needed before making recommendations to the industry.

Modification of norfloxacin inhibition of DNA gyrase induced by a 28 KDal DNA binding protein

We have previously studied a clinical isolate of Providencia stuartii which showed high levels of resistance to 4-quinolones, aminoglycoside and beta-lactam antibiotics (Landini et al., 1987). DNA gyrase from this isolate was inhibited for 50% of activity at a concentration of 15 microM of norfloxacin, which is about 5-fold higher compared to the 50% inhibitory concentration for a standard DNA gyrase. It has been described that 4-quinolone inhibition of DNA gyrase is caused by their binding to DNA and by the distortion induced in DNA tertiary structure, and that affinity binding of 4-quinolones is different for DNAs in different structures. In order to detect whether the interaction between pAT 153 and a protein able to modify DNA tertiary structure could affect norfloxacin inhibitory concentrations for DNA gyrase we purified from the clinical isolate of Providencia stuartii a DNA binding protein of about 28 KDal which induces changes in supercoiling degree of DNA. Assays of DNA gyrase activity were performed on the complex pAT 153-DNA binding protein-norfloxacin. Results showed an increase from 15 microM to 20 microM of 50% norfloxacin inhibitory concentration for DNA gyrase when pAT 153 was complexed with the 28 KDal protein.

Surveillance of antibiotic resistance in South East Asia

Antibiotic resistance in Gram-negative bacteria, particularly Salmonella and Shigella, requires surveillance worldwide. This study describes results of surveys in Hong Kong, Bangkok and Kuala Lumpur. All strains were isolated in hospitals which have large community catchment areas in addition to specialised hospital units. The prevalence of resistant strains was high in all areas. Gram-negative bacteria such as Enterobacter associated with hospital infections were resistant to penicillins and cephalosporins, with gentamicin resistance ranging from about 20% in Kuala Lumpur and Hong Kong, to 35% in Bangkok. Ninety-seven percent of Shigella isolated in Thailand were resistant to ampicillin. About 10% of Salmonella were resistant to chloramphenicol in all three centres.

Resistance to gentamicin and amikacin of gram-negative organisms isolated from horses

Resistance of gram-negative bacteria to gentamicin has become an increasingly common problem among clinical isolates from human beings. Susceptibility of isolates from horses to gentamicin and amikacin was evaluated for the period from July, 1983 to June, 1985. All isolates of Escherichia coli, and species of Enterobacter, Klebsiella, Proteus, and Pseudomonas examined were susceptible to amikacin, except 2 of the 46 Pseudomonas isolates. In contrast, 13 to 50% of isolates were resistant to gentamicin. Escherichia coli, and Klebsiella, Proteus, and Enterobacter species isolates were highly significantly more susceptible to amikacin (P less than 0.01) than to gentamicin. Pseudomonas spp (P = 0.13) were not significantly different in susceptibility to the 2 drugs. There was significant variation among genera in their susceptibility to gentamicin (P = 0.002), primarily because of the frequency of resistance in isolates of Klebsiella spp and Proteus spp, compared with the other 3 organisms (E coli, Enterobacter spp, and Pseudomonas spp). There was no significant difference of susceptibility to amikacin among the genera studied (P = 0.06).

[Susceptibility of clinical isolates to aztreonam]

In vitro antibacterial activities of 9 antibiotics including aztreonam (AZT) against clinically isolated Gram-negative bacteria were determined using MIC-2000 plus system. Bacteria were isolated from clinical materials in Saga Medical School during a period from May 1987 to March 1988. Summarized results were as follows: 1. AZT showed excellent antibacterial activities against Escherichia coli, Klebsiella pneumoniae, Proteus sp. and Haemophilus influenzae, and MIC80 values of AZT against these organisms were lower than 0.20 microgram/ml. 2. Antibacterial activities of AZT were superior to cephem antibiotics compared against Enterobacter aerogenes, Enterobacter cloacae, Citrobacter freundii and Serratia marcescens. 3. The MIC50 and MIC80 of AZT against Pseudomonas aeruginosa were 12.5 micrograms/ml and 25 micrograms/ml, respectively. 4. AZT did not show any antibacterial activity against Acinetobacter sp. and Xanthomonas maltophilia.

Interaction of the bisbiguanides chlorhexidine and alexidine with phospholipid vesicles: evidence for separate modes of action

Strains of Providencia stuartii with demonstrated resistance towards chlorhexidine did not show such resistance towards either of the related biguanide antiseptics, alexidine or vantocil. Alexidine promoted a significantly faster alteration in the permeability of Escherichia coli cell membranes towards various metal cations than chlorhexidine. Differential thermal analysis of various mixed lipid vesicles and pure phospholipid vesicles showed alexidine to share with vantocil the property of producing lipid phase separation and domain formation. It is suggested that the nature of the end-group on the biguanides affects the ability to produce lipid domains in cell membranes and this this might, in turn, affect activity and resistance patterns observed.

In vitro activity of pefloxacin compared with five other quinolones on nalidixic acid-resistant proteae species

The in vitro activity of pefloxacin, a new fluoroquinolone, was compared with that of 5 other quinolone compounds (nalidixic and pipemidic acids, norfloxacin, ciprofloxacin, and ofloxacin) against 416 strains of Proteae spp. isolated from urine specimens of hospitalized patients with acute urinary tract infections (UTI). Ciprofloxacin was the most active agent. Norfloxacin, ofloxacin, and pefloxacin were similarly active against Proteus strains (MIC90 = 0.39 microgram/ml). Against Providencia spp. pefloxacin and norfloxacin showed similar activity (MIC90 = 3.12 micrograms/ml). There is minimal discrepancy between minimum inhibitory concentrations and minimum bactericidal concentrations exhibited by the quinolones for all urinary tract pathogens tested. Our in vitro studies indicate that pefloxacin is an active antimicrobial agent and suggest that it will prove useful in the treatment of complicated urinary tract infections due to nalidixic acid-resistant Proteae spp.