Clindamycin, erythromycin, and roxithromycin inhibit the proinflammatory interactions of Pseudomonas aeruginosa pigments with human neutrophils in vitro

Clindamycin: A Comprehensive Status Report with Emphasis on Use in Dermatology

Clindamycin is a lincosamide antibiotic that has been used as a topical, oral, or injectable formulation for over five decades. It exhibits a narrow spectrum of microbiologic activity, primarily against gram-positive and anaerobic bacteria. In dermatology, clindamycin has been used primarily as a topical agent, usually for the treatment of acne vulgaris. Despite questions surrounding antibiotic resistance and/or its relative contribution to antibiotic treatment efficacy, a large body of data support the therapeutic value of topical clindamycin for acne vulgaris. As a systemic agent, clindamycin is used orally to treat a variety of cutaneous bacterial infections, and sometimes for acne vulgaris, with oral treatment for the latter less common in more recent years. The modes of action of clindamycin are supported by data showing both its anti-inflammatory and antibiotic mechanisms, which are discussed here along with pharmacokinetic profiles and structure-activity relationships. The diverse applications of clindamycin for multiple disease states, its efficacy, and safety considerations are also reviewed here, including for both topical and systemic formulations. Emphasis is placed on uses in dermatology, but other information on clindamycin relevant to clinicians is also discussed.

Antibiotic Resistance Patterns of Pseudomonas spp. Isolated From Raw Milk Revealed by Whole Genome Sequencing

Psychrotrophic bacteria in raw milk are most well known for their spoilage potential and the economic losses they cause to the dairy industry. Food-related psychrotrophic bacteria are increasingly reported to have antibiotic resistance features. The aim of this study was to evaluate the resistance patterns of Pseudomonas spp. isolated from bulk-tank milk. In total, we investigated the antibiotic susceptibility profiles of 86 Pseudomonas spp. isolates from raw milk. All strains were tested against 15 antimicrobial agents. Pseudomonas isolates were most highly resistant to imipenem (95.3%), followed by trimethoprim-sulfamethoxazole (69.8%), aztreonam (60.5%), chloramphenicol (45.3%), and meropenem (27.9%). Their multiple antibiotic resistance (MAR) index values ranged from 0.0 to 0.8. Whole-genome sequencing revealed the presence of intrinsic resistance determinants, such as BcI, ampC-09, blaCTX-M, oprD, sul1, dfrE, catA1, catB3, catI, floR, and cmlV. Moreover, resistance-nodulation-cell division (RND) and ATP-binding cassette (ABC) antibiotic efflux pumps were also found. This study provides further knowledge of the antibiotic resistance patterns of Pseudomonas spp. in milk, which may advance our understanding of resistance in Pseudomonas and suggests that antibiotic resistance of Pseudomonas spp. in raw milk should be a concern.

Efficacy of concomitant administration of clarithromycin and acetylcysteine in bronchiolitis obliterans in seventeen sulfur mustard-exposed patients: An open-label study

BACKGROUND

Victims of sulfur mustard (SM) gas exposure experience different types of chronic pulmonary disease, manifested as cough, sputum production, and dyspnea. Conventional therapies (eg, immunosuppressive drugs, corticosteroids) have not been effective in these patients.

OBJECTIVE

This study was carried out to determine the efficacy of concomitant administration of the macrolide clarithromycin and the mucolytic agent acetylcysteine in the treatment of bronchiolitis obliterans in SM-exposed patients.

METHODS

This open-label clinical study was conducted at the Research Center of Chemical Injuries, Baqiyatallah Medical Sciences University, Tehran, Iran. Clarithromycin and acetylcysteine were administered concomitantly for 6 months to male SM-exposed patients with chronic bronchitis and bronchiolitis obliterans who were nonresponsive to conventional treatments. Efficacy analysis included symptom assessment and pulmonary function tests (forced expiratory volume in 1 second [FEV1], forced vital capacity [FVC], and FEV1/FVC ratio) using spirometry, performed at baseline and after 2 and 6 months of treatment.

RESULTS

Seventeen male patients (mean [SD] age, 38.3 [5.3] years [range, 31-50 years]; mean [SD] body weight, 77.9 [15.7] kg) were included in the study. Cough and sputum production were each found in 10 of 17 patients (58.8%) at baseline and were improved in all 10 patients after the administration of clarithromycin and acetylcysteine. FEV1 and FVC also were improved, by mean (SD) 10.6% (9.7%) (P < 0.001 vs baseline) and 12.9% (13.6%) (P = 0.001 vs baseline). No significant change in FEV1/FVC ratio was found.

CONCLUSIONS

In this study of concomitant administration of clarithromycin and acetylcysteine for the treatment of bronchiolitis obliterans in SM-exposed patients, symptoms and pulmonary function were improved. These results may have been related to the therapeutic effects of a macrolide antibiotic on chronic bronchitis and bronchiolitis obliterans in these patients. Based on the results of this study, we recommend this treatment for chemical warfare victims with recurrent exacerbation of bronchitis who do not respond to conventional treatment.

Macrolide antibiotics in food-animal health

Several 14- and 16-membered-ring macrolide antibiotics have acquired important roles in the modern production of food animals. Macrolide antibiotics exhibit many similar antimicrobial properties whether used in veterinary or human medicine. In addition to their direct inhibitory action on micro-organisms, macrolides exert a variety of subinhibitory concentration (sub-MIC) effects that are being increasingly recognised as important factors in the explanation of therapeutic results. Macrolides achieve wide tissue distribution and high intracellular concentrations that contribute prominently to their efficacy. Another important factor governing efficacy is the complex interaction between macrolides, micro-organisms, and phagocytes that may enable the host defence system to enhance the antibiotic's inhibitory action. A potential role for macrolides in modulating inflammatory processes has also been recognised. In both sub-MIC effects and interactions with the host immune system, different macrolides exert different responses that may reinforce or oppose each other. This complexity of responses requires additional studies in appropriate disease states and animal species in order to elucidate a more comprehensive understanding and explanation of in vivo outcomes.

Nonantimicrobial Effects of Antibacterial Agents

One of the major advances in modern medicine was the development of antimicrobial chemotherapy. However, many antibacterial agents have unexpected or undesirable nonantimicrobial effects on humans. Microbes and man share many essentials of life, including DNA, adenosine triphosphate, and other biochemical pathways. Hence, some of these nonantimicrobial effects may also turn out to be pharmacologically useful. Oral hypoglycemic agents (i.e., sulfonylureas) and a certain diuretic agent (acetazolamide) are derivatives of sulfonamides. Erythromycin has been used clinically for its stimulatory effect on gastrointestinal motility. Macrolides, lincosamides, and tetracyclines have been known for their immunomodulatory effects. A tetracycline has been used to treat the syndrome of inappropriate antidiuretic hormone. Aminoglycosides may influence mucus production in patients with cystic fibrosis. Other antimicrobials may have side effects that are not therapeutically useful, such as osmotic diuresis with high-dose beta -lactam administration, neuromuscular blockade of aminoglycosides, dysglycemia of fluoroquinolones, and serotonin syndrome with oxazolidinones.

Therapy with macrolides in patients with cystic fibrosis

Cystic fibrosis affects 1/2500 individuals and is the most common lethal autosomal recessive disease in people of northern European descent. It is characterized by chronic infections with mucoid Pseudomonas aeruginosa and progressive deterioration of respiratory function. Much research has focused on the inflammatory component of the disease. Macrolide antibiotics are postulated to suppress inflammatory mediators and interfere with biofilm formation produced by P. aeruginosa. In vitro studies show promising results, and a limited number of human studies reported improvements in respiratory function with the drugs. Macrolide antibiotics are generally safe and well tolerated and may prove to be effective in patients with cystic fibrosis.

Anti-inflammatory effects of macrolide antibiotics

Macrolides are widely used as antibacterial drugs. Clinical and experimental data, however, indicate that they also modulate inflammatory responses, both contributing to the treatment of infective diseases and opening new opportunities for the therapy of other inflammatory conditions. Considerable evidence, mainly from in vitro studies, suggests that leukocytes and neutrophils in particular, are important targets for modulatory effects of macrolides on host defense responses. This underlies the use of the 14-membered macrolide erythromycin for the therapy of diffuse panbronchiolitis. A variety of other inflammatory mediators and processes are also modulated by macrolides, suggesting that the therapeutic indications for these drugs may be extended significantly in future.

[Macrolides and Pseudomonas aeruginosa infection]

Several unique effects of subinhibitory concentrations of C14 and C15 macrolides on Pseudomonas aeruginosa infection are described in vitro: P. aeruginosa virulence factors inhibition, bacterial biofilm disruption, P. glycoprotein expression upregulation, anti-inflammatory and immunoregulatory effects. Clinical trials in vivo are warranted to assess the potential usefulness of macrolides for treatment of chronic infections caused by P. aeruginosa.

Clindamycin suppresses endotoxin released by ceftazidime-treated Escherichia coli O55:B5 and subsequent production of tumor necrosis factor alpha and interleukin-1 beta

Treatment of septicemia caused by Escherichia coli with ceftazidime (CAZ) may be associated with the development of septic shock due to the release of bacterial lipopolysaccharide. We examined the suppressive effect of clindamycin (CLDM) on CAZ-induced release of endotoxin by cultured E. coli and the subsequent production of inflammatory cytokines (tumor necrosis factor alpha [TNF-alpha] and interleukin-1 beta [IL-1 beta]). E. coli ATCC 12014 was incubated in inactivated horse serum with or without CLDM for 1, 4, or 18 h, followed by the addition of CAZ and collection of the culture supernatant at 0, 1, and 2 h. The concentration of endotoxin in each sample was measured by a chromogenic Limulus test. Another portion of the culture supernatant was added to THP-1 cell culture and incubated for 4 h, and the concentrations of TNF-alpha and IL-1 beta in the supernatant were measured by an enzyme-linked immunosorbent assay. In the control group (no CLDM), CAZ administration resulted in significant increases in endotoxin, TNF-alpha, and IL-1 beta concentrations. Pretreatment of E. coli with CLDM for 4 or 18 h before the addition of CAZ significantly suppressed the concentrations of endotoxin, TNF-alpha, and IL-1 beta in a time-dependent manner. In addition, CAZ treatment transformed E. coli from rodshaped bacteria to filament-like structures, as determined by electron microscopy, while pretreatment with CLDM prevented these morphological changes. Our in vitro studies showed that CAZ-induced release of large quantities of endotoxin by E. coli could be suppressed by prior administration of CLDM.

Effects of erythromycin on chemoattractant-activated human polymorphonuclear leukocytes

1. Erythromycin (2-100 micrograms ml-1) produced a concentration-related inhibition of superoxide generation and elastase release induced by in vitro exposure of human polymorphonuclear leukocytes (PMNs) to the chemotactic peptide N-formylmethionyl-leucyl-phenylalanine (FMLP; 30 nM). 2. By contrast, erythromycin (100 micrograms ml-1) did not alter the leukotriene B4 production elicited by FMLP (30 nM; in the presence of thimerosal 20 microM) or the intracellular calcium changes promoted by FMLP (30 nM; in the absence or presence of thimerosal 20 microM). 3. These results indicate that by reducing chemoattractant-triggered release of oxidative and proteolytic mediators from human PMNs, erythromycin may have clinically useful antiinflammatory effects.