Virulence of non-β-lactamase-mediated ampicilin-resistant Haemophilus influenzae

Lg, Rubin; Pm, Mendelman; Rm, Rakita; Rosen, Henry

doi:10.1016/0378-1097(91)90389-r

Cited by 3 publications

(5 citation statements)

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“…Rubin et al [21] have suggested that such strains are less virulent than strains without alterations in PBPs, which might explain the low prevalence observed in most studies. While the role in therapeutic failure of such resistant strains has not been clear, ampicillin treatment failed in a patient with meningitis and endocarditis due to a BLNAR strain (ampicillin MIC of 6.25 Ìg/ml) [22].…”

Section: Discussionmentioning

confidence: 72%

“…All ß-lactamase-producing strains thus were ampicillin resistant (ampicillin MICs of 14 Ìg/ml). Although 35 ß-lactamase-negative strains were ampicillin-susceptible (MICs, &0.5 Ìg/ml), 28 ß-lactamase-negative strains (44.4% of all ß-lactamase-negative isolates) Chemotherapy 1999;45: [15][16][17][18][19][20][21] Seki/Kasahara/Ohta/Ohta/Saikawa/ Sumita/Yachie/Fujita/Koizumi …”

Section: Patient Characteristicsmentioning

confidence: 99%

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Increasing Prevalence of Ampicillin- Resistant, Non-Beta-Lactamase-Producing Strains of <i>Haemophilus influenzae</i> in Children in Japan

Seki

Kasahara²,

Ohta³

et al. 1999

Chemotherapy

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Among Haemophilus influenzae isolated from children with respiratory tract infections, the evolution of ampicillin resistance was investigated during 1996 and 1997 in Japan. β-Lactamase production was assessed and minimum inhibitory concentrations (MICs) of eight antimicrobial agents were determined using a broth microdilution method in Mueller-Hinton-lysed horse blood medium. Of 74 H. influenzae, 11 strains (14.9%) produce β-lactamase and were thus highly resistant to ampicillin (MIC of >4.0 µg/ ml). In addition, moderate resistance to ampicillin, defined as an MIC of ≧1.0 µg/ml, was noted in 44.4% of all β-lactamase-negative isolates. These β-lactamase-negative ampicillin-resistant (BLNAR) organisms were resistant to other cephalosporins such as cefpodoxime and cefdinir, while β-lactamase-producing strains were susceptible to them. Cefditoren, cefteram, and minocycline were active against all strains studied, whereas cefaclor and clarithromycin were inactive against all H. influenzae isolates in this study. Results indicate that BLNAR strains have emerged among children with respiratory tract infections in Japan.

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Section: Discussionmentioning

confidence: 72%

Section: Patient Characteristicsmentioning

confidence: 99%

Increasing Prevalence of Ampicillin- Resistant, Non-Beta-Lactamase-Producing Strains of <i>Haemophilus influenzae</i> in Children in Japan

Seki

Kasahara²,

Ohta³

et al. 1999

Chemotherapy

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“…This is in agreement with numerous previous surveillance studies, which have indicated that such observations remain uncommon (11,13,14). It has been postulated that BLNAR is associated with altered penicillin-binding proteins (PBPs) and might be due to a lower virulence of strains with abnormal PBPs (13,16,26).…”

Section: Discussionmentioning

confidence: 99%

Antimicrobial resistance patterns of Haemophilus influenzae isolated from patients with meningitis in São Paulo, Brazil

Casagrande

Vicente

Landgraf

et al. 2000

Braz J Med Biol Res

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From 1989 to 1995, a total of 391 Haemophilus influenzae isolates were recovered from the cerebrospinal fluid (CSF) of hospitalized patients in São Paulo, Brazil. The majority of strains were isolated from infants aged less than 5 years. Strains belonging to biotype I (64.7%), biotype II (34.5%) and biotype IV (0.76%) were detected. Ninety-nine percent of these strains were serotype b. Minimal inhibitory concentration (MIC) was determined for ampicillin, chloramphenicol and ceftriaxone. The ß-lactamase assay was performed for all strains. The rate of ß-lactamase producer strains ranged from 10 to 21.4% during a period of 7 years, with an overall rate of 13.8%. Of the 391 strains analyzed, none was ß-lactamase negative ampicillin resistant (BLNAR). A total of 9.7% of strains showed resistance to both ampicillin and chloramphenicol; however, 4% of them were resistant to ampicillin only and 2% to chloramphenicol. All strains were susceptible to ceftriaxone and the MIC 90 was 0.007 µg/ml, suggesting that ceftriaxone could be an option for the treatment of bacterial meningitis in pediatric patients who have not been screened for drug sensitivity.

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“…Another suggested reason for the limited clinical impact of H. influenzae with altered PBPs has been its virulence. Rubin et al (28) have shown in the infant rat model of bacteremia that the relationship between resistance and virulence in these , purulent effusion behind pars tensa and pars flaccida; o and p, purulent effusion behind pars flaccida;^and _, clear to slightly turbid effusion; ᮀ, no changes. NA, not applicable.…”

Section: Discussionmentioning

confidence: 99%

“…Data on the virulence of these strains are sparse, but it has been suggested that they may have a lower virulence potential. In the infant rat model of bacteremia, a reduced mortality and a reduced magnitude of bacteremia were observed after intraperitoneal inoculation of ampicillin-resistant transformant, nontypeable H. influenzae strains (28). However, both the site of infection and the in vivo proliferation were questioned.…”

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confidence: 99%

Amoxicillin treatment of experimental acute otitis media caused by Haemophilus influenzae with non-beta-lactamase-mediated resistance to beta-lactams: aspects of virulence and treatment

Melhus

Janson

Westman

et al. 1997

Antimicrob Agents Chemother

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Through alterations primarily in the penicillin-binding proteins, a non-beta-lactamase-mediated resistance to beta-lactams has evolved in Haemophilus influenzae. The virulence of these chromosomally changed strains has been questioned. To ascertain whether these alterations involve a reduction in virulence of H. influenzae and whether they could be advantageous for the bacterium during amoxicillin treatment of acute otitis media, a total of 70 Sprague-Dawley rats were challenged with a susceptible recipient strain or a genetically similar resistant transformant strain. Antibiotic therapy was started on day 3 after inoculation, and the animals were monitored by daily otomicroscopy and analysis of bacterial samples from middle ear effusions obtained on day 8, the last day of observation. The animals were also sacrificed on days 4 and 8 and after 2 months for morphological examination. Compared with the susceptible recipient strain, recovery from infections caused by the resistant transformant strain was delayed, and the late structural changes were more severe in the animals challenged with the latter strain. The results of the study indicate that chromosomal alterations mediating a relatively low level of resistance to beta-lactams may be advantageous for H. influenzae during antibiotic treatment of a local infection in the rat, and the alterations may occur without any significant loss of virulence.

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Virulence of non-β-lactamase-mediated ampicilin-resistant Haemophilus influenzae

Cited by 3 publications

References 0 publications

Increasing Prevalence of Ampicillin- Resistant, Non-Beta-Lactamase-Producing Strains of <i>Haemophilus influenzae</i> in Children in Japan

Increasing Prevalence of Ampicillin- Resistant, Non-Beta-Lactamase-Producing Strains of <i>Haemophilus influenzae</i> in Children in Japan

Antimicrobial resistance patterns of Haemophilus influenzae isolated from patients with meningitis in São Paulo, Brazil

Amoxicillin treatment of experimental acute otitis media caused by Haemophilus influenzae with non-beta-lactamase-mediated resistance to beta-lactams: aspects of virulence and treatment

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