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J D Cavallo

Publications and source records attributed to J D Cavallo.

49 records · Page 3Linked to original sources
PubMed1995

[Bactericidal activity of 6 antibiotics and 3 combinations against 6 strains of Salmonella isolated from blood].

The bactericidal activity of 6 antibiotics and 3 combinations was evaluated against 6 Salmonella strains isolated from blood: 3 sensitive to all antibiotics tested (1 Salmonella Typhi, 1 Salmonella Paratyphi A et 1 Salmonella Enteritidis) and 3 harbouring a TEM penicillinase (1 Salmonella Typhi, 1 Salmonella Virchow et 1 Salmonella Typhimurium). MICs of 6 antibiotics, ceftriaxone, cefotaxime, cefoperazone, ciprofloxacin, amikacin and chloramphenicol were determined by microdilution method in Mueller Hinton broth. The bactericidal activity of these antibiotics and 3 combinations (ciprocloxacin + ceftriaxone, ciprofloxacin + amikacin and ceftriaxone + amikacin) was determined by the killing curve method with 10(6) cfu/ml inocula and 4 x MIC for antibiotics concentrations. Chloramphenicol, only tested on typho-paratyphi strains, had only a bacteriostatic effect at 24 hours. Amikacin and ciprofloxacin had a faster and better bactericidal activity than cephalosporins. Combinations were either additive or synergistic. Those including amikacin had the best results, but any can be proposed for initial treatment of severe Salmonella infections in immunosuppressed patients.

Amikacin↗
PubMed1995

[Comparative activity of azithromycin against 100 strains of Neisseria gonorrhoeae].

Azithromycin is a new semisynthetic, acid stable C15 macrolid. In our study, we compared in vitro activity of azithromycin with 6 other antibiotics usually recommended for treatment of N. gonorrhoeae infections: erythromycin, ampicillin, amoxicillin, ceftriaxone, spectinomycin, ciprofloxacin. 100 strains have been selected: 95 clinical strains with different resistance patterns: 60 susceptible to beta-lactams, 25 PPNG, 10 chromosomal decreased susceptibility to beta-lactams. Among these strains, 13 had a decreased susceptibility to erythromycin (MIC: 2 and 4 mg/l) and 5 WHO reference strains: A: spectinomycin resistance, B: wild phenotype, C: chromosomal decreased susceptibility to penicillin and tetracycline, D: chromosomal resistance to penicillin and erythromycin+chromosomal decreased susceptibility to chloramphenicol, E: beta-lactamase producing strain (PPNG) and decreased susceptibility to tetracycline. MICs have been determined by GC agar dilution method. Azithromycin is more active than erythromycin on all N. gonorrhoeae patterns with a two log 10 difference for MIC50 and MIC90 (p < 0.0001). Because of pharmacokinetic properties and activity against Chlamydia trachomatis and urogenital mycoplasms often associated with N. gonorrhoeae, azithromycin is a good alternative for the treatment of genital infections.

Anti-Bacterial Agents↗
PubMed1995

[Antibiotic sensitivity to epidemic strains of Vibrio cholerae and Shigella dysenteriae 1 isolated in Rwandan refugee camps in Zaire].

Multiresistance or epidemic enteric bacteria to antibiotics greatly complicates treatment, and in some cases prophylaxis, of severe invasive gastroenteritis. During the summer of 1994, two epidemics of diarrhea, one due to Vibrio cholerae and the other to Shigella dysenteriae 1 isolated from the Goma and Bukavu camps was determined by measurement of the Agar Minimal Inhibitory Concentration. Multiresistance to tetracyclins, aminopenicillins, trimethoprimsulfamethoxazole, and nifuroxazide was observed. After intensive treatment mutant forms of both bacteria resistant to nalidixic acid rapidly appeared. Only fluoroquinolones remained active on these mutant strains, but the availability of this agent in Africa is restricted due to cost. The most effective way of preventing resistance is to limit the spread of enteric infections by health education and improvement of hygiene. This can be difficult during wartime.

Cholera↗
PubMed1994

[In vitro activity of meropenem and seven other beta-lactam antibiotics against K.pneumoniae and enterobacteriaceae producing beta-lactamases with extended spectrum].

Meropenem is a broad antibacterial spectrum carbapenem with a good activity on betalactam resistant Gram-negative bacilli. 120 non repetitive strains isolated from clinical samples from 1989 to 1992 were selected: 60 K. pneumoniae, 7 E. coli, 2 E. aerogenes and 1 S. marcescens with extended spectrum betalactamases (23 CTX-1, 18 SHV-2, 5 SHV-3, 16 SHV-4, 4 SHV-5, 3 CTX-1 + SHV-4, 1 CAZ-1), 10 K. pneumoniae with broad spectrum TEM-1 enzyme, and 40 K. pneumoniae with only SHV-1 chromosomal betalactamase. Determination of Minimal inhibitory concentrations (MIC) was done by agar dilution method for meropenem and 7 other betalactams (amoxicillin + clavulanic acid 2 mg/l, piperacillin + tazobactam 4 mg/l, cefoxitin, cefotetan, cefotaxime, ceftazidime, imipenem). All antibiotics except amoxicillin + clavulanic acid are active against strains with constitutive penicillinase. For strains with TEM-1 penicillinase, cephamycins, third generation cephalosporins and carbapenems are active. For strains with different extended spectrum betalactamases only cephamycins and carbapenems are efficious. There is no difference according to the period of isolation: 1989-90 or 1991-92. Meropenem has the best in vitro activity (MIC50 = 0.03 mg/l) for all strains independently of the nature of betalactamase.

Anti-Bacterial Agents↗
PubMed1994

[In vitro bactericidal activity of seven antibiotics and four combinations against Neisseria meningitidis].

The authors studied, with a time-kill curve method, in a derived Hafiz medium broth the bactericidal effect of 7 antibiotics and 4 associations against N. meningitidis. Their results show a better bactericidal effect for penicillin G, ampicillin and chloramphenicol. Pefloxacin and ceftriaxon are less efficient. The association ampicillin + chloramphenicol in vitro shows no antagonism and has a good bactericidal activity at the early stages of bactericidal killing with N. meningitidis.

Ampicillin↗
PubMed1994

[Value of the E-test for the determination of the susceptibility to antibiotics of Neisseria meningitidis].

The E-test was evaluated by comparison with the reference agar dilution method on 50 N. meningitidis strains belonging to serotypes A [13], B [17] and C [12] or not agglutinated, isolated in France and Djibouti from cerebrospinal fluid. All strains were sensible by the reference method to penicillin G, cefotaxime, chloramphenicol, ciprofloxacin, doxycyclin, rifampicin. For erythromycin, some strains were intermediate (7/50). N. meningitidis serogroup A ATCC 13077 was used as control. The E-test quantitative accuracy compared with agar dilution results was 80% (+/- 1 log2) or 97% (+/- 2 log2). The E-test generally showed lower inhibitory concentration values than the agar dilution method. Some technical problems appear in our experience: agar plates must be well dried; on 85 mm diameter agar plates only one strip can be tested. The E-test for determination of antibiotic resistance of N. meningitidis is an easy but expensive method, which give reliable results with agar dilution.

Anti-Bacterial Agents↗
PubMed1994

[Determination of the susceptibility of staphylococci and enterococci to plycopeptides by the E-test method].

E-test was evaluated by comparison with the reference agar dilution method on 15 enterococci and 15 staphylococci with variable resistance to glycopeptides and isolated from clinical samples: 15 enterococci with 3 glycopeptide-resistant (2 E. facalis and 1 E. faecium), 1 glycopeptide intermediate E. gallinarum and 11 glycopeptide-sensible E. faecalis; 15 staphylococci with 4 teicoplanine-resistant (1 S. aureus, 1 S. epidermidis and 2 S. hominis), 3 teicoplanin-intermediate (1 S. epidermidis, 2 S. haemolyticus) and 8 teicoplanin sensible strains (6 S. aureus, 1 S. epidermidis and 1 S. hominis). Repeatability (10 determinations by strain) and exactitude were tested for all strains. Our data shows very good results for repeatability and exactitude with the reference method except in the case of coagulase negative staphylococci and teicoplanin. Some technical problems appear in our experience: for staphylococci, a 48 h incubation is necessary to detect teicoplanin-intermediate strains but 24 h is sufficient for enterococci. E-test is expensive, require a strict methodology, but is a good method to detect glycopeptide resistance for staphylococci and enterococci except for coagulase negative staphylococci and teicoplanine.

Bacteriological Techniques↗
PubMed1994

[Value of the score for Gram strains in the diagnosis of bacterial vaginosis].

The interpretation of Gram-stained slides of vaginal swab specimens is evaluated for the diagnosis of bacterial vaginosis and correlated with the isolation bacteria and clinical signs: thin homogeneous vaginal discharge, pH > or = 4.7, amine odor and presence of clue cells. Gram stained smears were scored following a morphotype classification: (a)-Lactobacillus morphotypes (scored 4 to 0), (b)-small Gram negative (G. vaginalis, scored 0 to 4), (c)-curved Gram variable rods (Mobiluncus morphotypes, scored 0 to 2). The scoring system (0 to 10) was a weighted combination of these morphotypes: a+b+c. The criterion for bacterial vaginosis was a score > or = 7, a score of 0 to 6 was considered as no bacterial vaginosis. Samples of 709 women, aged 18 to 84 (mean age = 39.7) were examined. The prevalence of G. vaginalis culture was 12.5%, and Mobiluncus infection occurred in 1.5%. The frequency of M. hominis was diagnosed in 2.8% of women. A score of 7 to 10 on Gram stain was observed in 9.7% in the population. Compared to G. vaginalis culture, Gram stained smear was more sensitive (0.71) than clinical signs of bacterial vaginosis (0.46). The specificity was similar with the two methods. The assessment of G. vaginalis morphotypes was highly correlated with the G. vaginalis culture (p < 0.001, OR = 248). The infection of T. vaginalis or Candida sp. was never associated with a score > or = 7. The Gram-stained smear is a cheap, fast and easy method. It provides good results for diagnosis of bacterial vaginosis.

Bacteroidaceae Infections↗
PubMed1993

[Evaluation of rapid screening tests in the diagnosis of urinary infections].

Bacterial urine examination is the main bacterial examination used in microbiology laboratories. The comparative interest of urine aspect associated with rapid screening tests (catalase, leucocyte esterase, nitrite) and different urine examination methods (Gram stain of sediment, direct examination on Malassez cell and on centrifuged urine pellet) are evaluated for negative predictive value of urinary tract infection. In out-patient, the association urine aspect-leucocyte esterase has the best negative predictive value for urinary tract infection (99.4%). Either in outpatients or in hospitalized patients, the association Gram stain of sediment-leukocyturia evaluation has the best negative predictive value for urinary tract infection (100%). This data allows in our population to give back negative results without culture.

Bacteriological Techniques↗
PubMed1993

[Antibiotic sensitivity of 140 strains of Shigella isolated in Djibouti].

Shigellae are the most frequently isolated invasive bacteria in Djibouti. 140 clinical strains collected during an eight months period have been studied for their in vitro susceptibility to antibiotics mainly used in treatment and prophylaxis by measure of MIC (agar dilution) for all antibiotics except for trimethoprim-sulfamethoxazole, trimethoprim and sulfamethoxazole (disk diffusion on lysed horse blood medium). Characterization of beta-lactamase is carried out for all strains resistant to amoxicillin and for all S. sonnei. The overall prevalence of resistance to amoxicillin is 41.7% (penicillinase TEM-1, OXA-1 and OXA-3 alone or associated) to tetracyclines 97.1% and to trimethoprim-sulfamethoxazole 51.4%. This prevalence is particularly high for amoxicillin with S. flexneri and for trimethoprim-sulfamethoxazole with S. sonnei. All strains of S. sonnei have a low level chromosomal cephalosporinase without phenotypic expression. Among 68 strains sensitive to trimethoprim-sulfamethoxazole, 39 are resistant to sulfamethoxazole alone. All strains are sensitive to nalidixic acid and fluoroquinolones. These data allows us to recommend fluoroquinolones for treatment and prophylaxis of shigellosis in Djibouti.

Ampicillin↗
PubMed1992

[Rapid diagnosis of malaria. The microwave furnace].

Thick blood is a well known method for malaria diagnosis, very faithful and sensitive, but it could not be used in emergency because it had to dry for many hours. Micro-wave over allows a quick drying (two minutes). Do it can now be used in emergency.

Animals↗
PubMedDate not supplied

Effect of beta-lactam antibiotics on the in vitro development of resistance in Pseudomonas aeruginosa.

OBJECTIVE: To investigate whether stepwise selection of resistance mutations maz mirror the continued bacterial exposure to antibiotics that occurs in the clinical setting. METHODS: We examined the in vitro development of resistance to a number of commonly used antibiotics (cefepime, cefpirome, ceftazidime, cefataxime, piperacillin and imipenem) in Pseudomonas aeruginosa, a significant nosocomial pathogen. Stepwise resistance was assessed by serial passage of colonies located nearest to the inhibition zone on antibiotic-containing gradient plates. RESULTS: The lowest frequencies of spontaneous resistance mutations were found with cefepime and imipenem; these drugs also resulted in the slowest appearance of resistance of spontaneous resistance mutations. In five wild-type P. aeruginosa strains, cefepime-selected isolates required a mean of 30 passages to reach resistance; resistance occurred more rapidly in strains selected with other cephalosporins. P. aeruginosa strains that produced beta-lactamase or non-enzymatic resistance generally developed resistance more rapidly than wild-type strains. For most strains, resistance to all antibiotics except imipenem correlated with increased levels of beta-lactamase activity. Cross-resistance of cephalosporin-selected resistant mutants to other cephalosporins was common,. Cephalosporin-resistant retained susceptibility to imipenem and ciprofloxacin. CONCLUSIONS: From our in vitro study, we can conclude that the rate of development of resistance of P. aeruginosa is lower with cefepime compared with other cephalosporines.

Anti-Bacterial Agents↗