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Biomedical subjects

H O Hallander

Publications and source records attributed to H O Hallander.

At least 55 records · Page 3Linked to original sources
PubMed1982

Synergism between aminoglycosides and cephalosporins with antipseudomonal activity: interaction index and killing curve method.

Combinations of gentamicin with cefotaxime, moxalactam, and ceftazidime were tested against 43 bacterial strains, most of them blood isolates. With an interaction index of less than or equal to 0.5 as borderline, synergism was demonstrated against 30 to 40% of the strains by the fractional inhibitory concentration index and against 50 to 70% by the fractional bactericidal concentration index. The reproducibility of the index was within +/- 0.2 for two-thirds of 40 repetitive assays and within +/- 0.4 to 0.5 for all of these assays. Similar results were obtained when netilmicin was substituted for gentamicin. The killing curve system for studying antibiotic synergism was standardized to give results comparable to those obtained with the interaction index. This was achieved when one-half of a previously determined minimum bactericidal concentration was used for single drugs and the amount of antibiotic was at least halved again when drugs were used in combination. An initial bacterial concentration of 10(5) to 10(6) colony-forming units per ml is recommended. Given these conditions, synergism could be defined as a 2-log 10 or more decrease in viable count given by both drugs together, as compared with the more active of the pair after 24 h. Prediction of killing curve results could then be obtained with the fractional bactericidal concentration index. When cephalosporins and gentamicin were combined from the start, the beta-lactam antibiotics were less susceptible to inactivation, as demonstrated in time-killing assays. If one of the antibiotics were added after 24 h, synergism was not demonstrable. The results indicate that the new cephalosporins may be advantageously combined with aminoglycosides.

Aminoglycosides↗
PubMed1981

Comparison of direct and standardized antibiotic susceptibility testing in bacteriuria.

In clinical isolates of bacteria from urine, the antibiotic susceptibility was tested with a direct disc diffusion method in which the inoculum was not primarily standardized. The results were compared with those from parallel tests using standardized inoculum. Of a total 2,272 urine specimens, 700 were accepted for direct susceptibility testing, 189 were not accepted because of mixed culture or indistinct inhibition zones. The overall concordance between the direct and the standardized tests was 95.8% (2,800 observations with 118 discordant results). The direct diffusion method used in this way is time saving and economical and can reliably be used in a clinical microbiological laboratory serving mainly outpatients.

Anti-Bacterial Agents↗
PubMed1980

Collection and transport of specimens for anaerobic culture.

By comparative studies of sampling methods it was shown that specimens should be obtained preferably by aspiration in order to avoid contamination by anaerobic flora. Anaerobic transport systems are recommended, though some anaerobic strains tolerate exposure to air surprisingly well. A gassed-out tube or vial is the method of choice for transporting fluid specimens for anaerobic culture.

Anaerobiosis↗
PubMed1980

Relationship between bacterial contamination and alveolitis after third molar surgery.

The frequency of alveolitis after third molar surgery was studied in three groups of 40 patients each. One group was premedicated with penicillin V, another with scopolamine, and the third group received no premedication. The respective frequencies of alveolitis were 5, 2.5 and 32.5 % (P less than 0.01 and P less than 0.001). The aerobic flora in blood sampled from the socket before suturing was significantly reduced (P less than 0.05) in the penicillin group as compared with the controls. In alveolar blood clot sampled 48 h postoperatively, both aerobes and anaerobes were significantly diminished (P less than 0.01). The concentration of penicillin V in alveolar blood ranged from 0.8 to 9.5 mg/l. The total bacterial content in alveolar blood before suturing showed poor correlation with the development of alveolitis. Abundant growth of aerobes was found, however, in 75 % of the patients with alveolitis, but in only 47 % of those without this complication.

Adolescent↗
PubMed1980

Gentamicin resistance in gram-negative bacilli: occurrence of modifying enzymes and their influence on susceptibility testing.

Among 272 gram-negative bacilli, regarded as strains with reduced susceptibility to gentamicin by the disc test, 156 strains were resistant (greater than or equal to f microgram/ml) by the agar dilution method. Altogether 76% of the 156 strains were cross-resistant to tobramycin, kanamycin, streptomycin and amikacin. Amikacin showed the highest antibacterial activity in vitro. 32 of the resistant strains produced acetylating or adenylylating enzymes, which caused resistance. The production of enzymes was not limited to any genera. Complete cross-resistance to aminoglycoside antibiotics was recorded in 45%, 98% and 22% respectively, of Pseudomonas aeruginosa, Ps. maltophilia and other gram-negative rods. Enzyme-producing strains were not cross-resistant to all aminoglycosides. Changes in MICs and inhibition zones with different inocula among enzyme-producing strains emphasize the importance of standardized inocula in susceptibility testing.

Aminoglycosides↗
PubMed1978

beta-lactamase production by strains of Escherichia coli of intermediate susceptibility to beta-lactam antibiotics. A study of their clinical significance in urinary tract infection.

In a prospective study of patients treated with cephalexin or co-trimoxazole, almost all isolated E. coli strains of intermediate susceptibility to ampicillin or cephalosporin (MIC 2-16 microgram/ml) were shown to produce beta-lactamase detectable with a chromogenic cephalosporin substrate, or by the clover-leaf test or the acidimetric method. When assayed in preparations of sonicated bacteria, the enzyme had a cephalosporinase-substrate profile in a large majority of cases. In order to evaluate the clinical significance of this beta-lactamase production, 48 patients with urinary tract infection (UTI) were treated with cephalexin, an antibiotic hydrolysed by the enzyme. Forty-three additional patients were treated with co-trimoxazole for comparison. A statistically significant difference in cure rate (p less than 0.05) was found after 2 weeks. Six recurrences occurred in the cephalexin group and none in the co-trimoxazole group. However, after six weeks there were 8 and 5 recurrences, respectively (p less than 0.05). There were no differences in beta-lactamase activity or MIC/MBC between initial strains and isolates from recurrent UTI. Thus, the recurrent infections were not due to emergence of resistance.

Adolescent↗
PubMed1977

Pharmacological and clinical study of bacampicillin in acute peritonsillitis--a comparison with ampicillin.

The pharmacological and clinical properties of bacampicillin in three dosage groups were studied in 66 hospitalized patients with unilateral acute peritonsillitis in a comparison with ampicillin. Bacampicillin is a new semisynthetic aminopenicillin which is rapidly converted to ampicillin but is better absorbed. Both drugs were given orally. The mean individual peak serum levels achieved with 200, 400, and 800 mg of bacampicillin in the first morning dose were 4.9, 6.8, and 11.9 mg/liter, respectively, with an almost linear dose response. The peak level of 800 mg of bacampicillin was significantly higher than the 6.8 mg/liter noted after a nearly equimolar dose of 500 mg of ampicillin. A linear relationship was also seen between dose and area under the serum concentration-time curve. Preliminary antibiotic concentration studies in five patients indicated therapeutic levels in peritonsillar pus. Beta-streptococci alone or in combination with anaerobes were isolated from about half of the abscesses, whereas anaerobes were isolated from the other half. Treatment was supplemented by surgical procedures in the majority of cases. The clinical effect was good in all treatment groups, with only one relapse. All beta-streptococci were eliminated during therapy. The total number of gastrointestinal side effects was significantly lower in patients treated with bacampicillin, although the difference in frequency of diarrhea alone was not significant.

Abscess↗
PubMed1977

Group B beta-hemolytic streptococci as an important cause of perinatal mortality.

Bacteriological and pathological examinations of all 73 stillborn infants and 96 infants dying soon after delivery in Västerås, Sweden during the period 1971-1974 are reported. 35 infants had a severe infection. Beta-hemolytic streptococci group B were isolated in 7 cases from different organs. Intrauterine death occurred in 2 cases; 4 liveborn infants showed early signs of respiratory distress, apneic episodes and cyanosis; 1 infant showed signs of intrauterine asphyxia and was severely asphyctic at birth. Thus, infection with group B streptococci occurred in 20% of the infants who succumbed to infections during this period.

Adult↗
PubMed1976

Tone audiometry control of children treated for meningitis with large intravenous doses of ampicillin.

Thirty-seven children treated for bacterial meningitis with ampicillin in high doses were followed up with audiometric control. Defects were recorded in 6 cases. Two of these were ascribed to chronic otosalpingitis. In 4 patients with sensorineural hearing loss, 3 were unilateral, and in only one case was the damage bilateral. Even here there was a previous history of hearing loss. A suggested ototoxicity of ampicillin could not be confirmed.

Ampicillin↗
PubMed1976

Microbiological aspects on peritonsillar abscesses.

In 37 patients with unilateral quinsy put was collected with a syringe technique and bacteriologically examined. Beta-hemolytic streptococci were isolated from 17 abscesses; in 8 of these, however, together with other bacteria, mainly anaerobes. Anaerobic bacteria, often more than one species, were found in 28 abscesses. Streptococcal serology including AST-O, Streptozyme and separate ADNAse test showed high titres or titre rises in 22 out of 30 examined cases. There was one case with beta-hemolytic streptococci in the abscess but negative serology. In the remaining cases a possible primary etiological role of anaerobes is suggested. The effect of combined surgical drainage and treatment with antibiotics (ampicillin or penicillin V) was good.

Bacteriological Techniques↗
PubMed1975

Influence of the collection and transport of specimens on the recovery of bacteria from peritonsillar abscesses.

In 30 patients with peritonsillar abscesses, pus was obtained by aspiration and by taking a swab after incision; bacterial recovery was compared. Although processed in the laboratory within 2 h, swab speciments gave results comparable to syringe specimens in only 9 of 13 patients with beta-hemolytic streptococci and 7 of 25 patients with anaerobic bacteria. Both kinds of microorganisms were lost in some cases but appeared as additional flora in others. The poor results from the swab technique was ascribed to overgrowth of respiratory flora contaminating the sample after incision. In aspirated pus kept in the syringe, or transferred to anaerobic transporters, the microbial flora was unchanged for 24 to 48 h. Some anaerobes also survived on agar slants for 24 h, but specially designed anaerobic transporters are recommended.

Anaerobiosis↗
PubMed1972

Identification of cephalosporin-resistant Staphylococcus aureus with the disc diffusion method.

Methicillin-resistant strains of Staphylococcus aureus, in total 84, representing 16 laboratories in 8 different countries were all resistant to 32 mug of cephalothin per ml with the same typical heteroresistant pattern. With the disc diffusion method, they were easily detected when cephalexin discs were used. With cephalothin discs, on the other hand, 26 to 49% would have been falsely categorized as Group I or II after 24 hr. It is recommended that susceptibility testing of S. aureus to cephalosporins by using the paper disc method be performed with 30-mug cephalexin discs on Mueller-Hinton agar without blood. With an inoculum of 10(6) bacteria/ml, an incubation temperature of 30 C, and an incubation time of 24 hr, a zone of less than 10 mm indicates presumptive heteroresistance. This corresponds to the international recommendation with a minimal inhibitory concentration of 32 mug/ml as the upper limit of Group II.

Cephalosporins↗