Post-antibiotic effect of azithromycin and erythromycin on streptococcal susceptibility to phagocytosis

Ramadan, Mohamed A.; Tawfik, Abdulkader F.; Shibl, Atef M.; Gemmell, C. G.

doi:10.1099/00222615-42-5-362

Cited by 39 publications

(43 citation statements)

References 19 publications

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“…B. pseudomallei is an intracellular pathogen and has been found to be able to resist intracellular killing by phagocytes (13,35). Many studies have demonstrated that subinhibitory concentrations of antibiotics increase the susceptibilities of bacteria to phagocytosis or killing by phagocytes (3,4,27,30). Not only is B. pseudomallei resistant to killing by monocytes, but it also kills monocytes.…”

Section: Discussionmentioning

confidence: 99%

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Modified Virulence of Antibiotic-Induced Burkholderia pseudomallei Filaments

Chen

Sun

Chua

et al. 2005

Antimicrob Agents Chemother

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Melioidosis is a life-threatening bacterial infection caused by Burkholderia pseudomallei. Some antibiotics used to treat melioidosis can induce filamentation in B. pseudomallei. Despite studies on the mechanism of virulence of the bacteria, the properties of B. pseudomallei filaments and their impact on virulence have not been investigated before. To understand the characteristics of antibiotic-induced filaments, we performed in vitro assays to compare several aspects of virulence between normal, nonfilamentous and filamentous B. pseudomallei. Normal, nonfilamentous B. pseudomallei could cause the lysis of monocytic cells, while filaments induced by sublethal concentrations of ceftazidime, ofloxacin, or trimethoprim show decreased lysis of monocytic cells, especially after prolonged antibiotic exposure. The motility of the filamentous bacteria was reduced compared to that of nonfilamentous bacteria. However, the filamentation was reversible when the antibiotics were removed, and the revertant bacteria recovered their motility and ability to lyse monocytic cells. Meanwhile, antibiotic resistance developed in revertant bacteria exposed to ceftazidime at the MIC. Our study highlights the danger of letting antibiotic concentration drop to the MIC or sub-MICs during antibiotic treatment of melioidosis. This could potentially give rise to a temporary reduction of bacterial virulence, only to result in bacteria that are equally virulent but more resistant to antibiotics, should the antibiotics be reduced or removed.

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Section: Discussionmentioning

confidence: 99%

“…Many have reported on the altered adherence and phagocytosis of antibiotic-induced filaments in other bacteria (3,4,27). Decreased phagocytosis of these filaments was likely due to mechanical constraints.…”

Section: Mics and Mbcs Of Antibioticsmentioning

confidence: 99%

Modified Virulence of Antibiotic-Induced Burkholderia pseudomallei Filaments

Chen

Sun

Chua

et al. 2005

Antimicrob Agents Chemother

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“…The other accompanying effects include changes in cell morphology (Hanberger et al, 1993), inhibition of enzyme and toxin production (Shibl et al, 1994), loss of adhesive properties and reduction of cell-surface hydrophobicity (Shibl et al, 1994;Ramadan et al, 1995), and increased susceptibility to host humoral and cellular immunity (Minguez et al, 1994;Ramadan et al, 1995). Many of these effects are probably overlapping and closely linked.…”

Section: (V) Susceptibility Testingmentioning

confidence: 99%

Oral Candidal Infections and Antimycotics

Ellepola

Samaranayake

2000

Critical Reviews in Oral Biology & Medicine

210

236

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The advent of the human immunodeficiency virus infection and the increasing prevalence of compromised individuals in the community due to modern therapeutic advances have resulted in a resurgence of opportunistic infections, including oral candidoses. One form of the latter presents classically as a white lesion of "thrush" and is usually easily diagnosed and cured. Nonetheless, a minority of these lesions appears in new guises such as erythematous candidosis, thereby confounding the unwary clinician and complicating its management. Despite the availability of several effective antimycotics for the treatment of oral candidoses, failure of therapy is not uncommon due to the unique environment of the oral cavity, where the flushing effect of saliva and the cleansing action of the oral musculature tend to reduce the drug concentration to sub-therapeutic levels. This problem has been partly circumvented by the introduction of the triazole agents, which initially appeared to be highly effective. However, an alarming increase of organisms resistant to the triazoles has been reported recently. In this review, an overview of clinical manifestations of oral candidoses and recent advances in antimycotic therapy is given, together with newer concepts, such as the post-antifungal effect (PAFE) and its possible therapeutic implications.

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“…The PAE value of the antibiotic for the isolate was 1 h. In our former experiments the PAE values were significantly different for other species of streptococci -3.4 and 3.5 h for the S. anginosus strains 2 and 2,8 h for the group A streptococcus 15,16 . RAMADAN et al 35 reported that erythromycin and azythromycin induced PAE against group A streptococci -2.4 and 4.3 h respectively -and several other studies have assessed the PAE of antimicrobials on Gram-positive cocci.…”

Section: Discussionmentioning

confidence: 99%

“…In another investigation we also observed that treatment of group A streptococci with penicillin did not influence the cell-surface hydrophobicity as the magnitude of changes in value of angles did not differ significantly 15 . RAMADAN et al 35 showed a decrease of the group A streptococcal cell-surface hydrophobicity during the PAE induced by azythromycin and erythromycin. The alterations could be related to mechanisms such as effects on the bacterial surface, formation of aberrant adhesins, suppression of production of surface adhesins or even absence of expression of these adhesions 1,24.37,41 .…”

Section: Discussionmentioning

confidence: 99%

Cell surface hydrophobicity and adherence of a strain of group B streptococci during the post-antibiotic effect of penicillin

Araújo¹,

Oliveira²,

Mattos³

et al. 2008

Rev. Inst. Med. trop. S. Paulo

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SUMMARYThe minimum inhibitory concentration and post-antibiotic effects of an antimicrobial agent are parameters to be taken into consideration when determining its dosage schedules. The in vitro post-antibiotic effects on cell surface hydrophobicity and bacterial adherence were examined in one strain of group B streptococci. Exposure of the microorganism for 2 h at 37 °C to 1 x MIC of penicillin induced a PAE of 1.1 h. The cell surface charge of the Streptococcus was altered significantly during the postantibiotic phase as shown by its ability to bind to xylene: hydrophobicity was decreased. Bacterial adherence to human buccal epithelial cells was also reduced. The results of the present investigation indicate that studies designed to determine therapeutic regimens should evaluate the clinical significance of aspects of bacterial physiology during the post-antibiotic period.

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Post-antibiotic effect of azithromycin and erythromycin on streptococcal susceptibility to phagocytosis

Cited by 39 publications

References 19 publications

Modified Virulence of Antibiotic-Induced Burkholderia pseudomallei Filaments

Modified Virulence of Antibiotic-Induced Burkholderia pseudomallei Filaments

Oral Candidal Infections and Antimycotics

Cell surface hydrophobicity and adherence of a strain of group B streptococci during the post-antibiotic effect of penicillin

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