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1.
Ear Nose Throat J ; : 1455613231186891, 2023 Aug 19.
Article in English | MEDLINE | ID: mdl-37596941

ABSTRACT

Nodular fasciitis is a relatively uncommon disorder that occurs in soft tissues and results in a rapidly growing mass predominately found in adults. Proliferative fasciitis is a rarer variant of nodular fasciitis that is typically found in adults over age 40 and is extremely rare in pediatric patients. This case report involves a pediatric patient who presented with a large, posterior, rapidly growing mass on the right ear. This was excised and the subsequent biopsy required several pathology consultations and opinions. Multiple immunohistochemical and molecular studies eventually led to the findings of spindle cell mesenchymal neoplasm, consistent with proliferative fasciitis of pediatric type.

2.
Otolaryngol Head Neck Surg ; 163(2): 280-283, 2020 08.
Article in English | MEDLINE | ID: mdl-32513045

ABSTRACT

OBJECTIVES: The primary objective of this study was to compare the protection afforded by a standard face shield design with a new enhanced design in a controlled setting. METHODS: This study was exempted from review by institutional review board waiver. A flexible fiberoptic endoscopy was placed through stellate openings in the standard face shield and the enhanced face shield. A series of simulated coughs were created with bursts of fluorescein dye through an atomizer tip placed within the test participant's mouth. Ultraviolet lighting illuminated the test area, and areas of dye splatter were noted. RESULTS: Fluorescein dye is easily aerosolized along the lateral inferior aspect of a standard shield with significant contamination of the surrounds. The enhanced face shield maintained a barrier to the aerosolized dye. DISCUSSION: Face shields, rather than face masks, should be considered a preferred alternative for the public and for health care professionals alike, as they address many of the personal protective equipment concerns especially during the COVID-19 pandemic. Otolaryngologists are at high risk from aerosol-generating procedures, such as flexible fiberoptic endoscopy, even when wearing personal protective equipment. Here we describe a uniquely designed face shield to be worn by the patient as another layer of protection for the environment and for medical personnel. IMPLICATIONS FOR PRACTICE: During the course of a flexible fiberoptic endoscopy, medical personnel are safely isolated from potential infectious particles with a newly designed face shield.


Subject(s)
Betacoronavirus , Coronavirus Infections/transmission , Endoscopy , Infectious Disease Transmission, Patient-to-Professional/prevention & control , Personal Protective Equipment , Pneumonia, Viral/transmission , COVID-19 , Endoscopes , Equipment Design , Humans , Pandemics , Proof of Concept Study , SARS-CoV-2
3.
Pediatr Infect Dis J ; 39(9): e226-e233, 2020 09.
Article in English | MEDLINE | ID: mdl-32453194

ABSTRACT

BACKGROUND: The human microbiome evolves rapidly in early life with contributions from various factors such as diet, delivery mode, medical history, antibiotics exposure, genetics, immunomodulators and the environment. A high use of antibiotics in pediatric outpatient settings has been well documented, and improvement in antibiotic selection is required to reduce the risks of antibiotic resistance and disruption of the microbiome. METHODS: We performed an exploratory study using 16S rRNA gene-based sequencing to characterize the gut and nasopharyngeal microbiome of children (n = 50) age 1-6 years of age in a pediatric otolaryngology practice. RESULTS: Relative abundance of Haemophilus and Moraxella were higher in nasopharyngeal swabs, while Prevotella, Bacteroides, Porphyromonas and Faecalibacterium were highly abundant in rectal swabs. The gut microbiome composition in children <2 years old was different compared with children ≥2 years age. Gut bacterial diversity increased with an increase in age of the children. Children taking probiotics had a notable increase in abundance of potentially beneficial gut bacteria such as Bacteroides and Akkermansia. The nasopharyngeal microbiome differed between children who received antibiotics in the 3 months before sample collection compared with those that did not. Haemophilus spp. was highly abundant in children who received antibiotics 3 months before sampling. CONCLUSIONS: The pediatric nasopharyngeal and rectal microbiomes differ in bacterial composition and diversity. The increased abundance of Haemophilus spp. in the nasopharyngeal microbiome of children who received antibiotics during the 3 months before sampling suggests a potential impact of antibiotics in colonization with the otopathogen and may be relevant to clinical practice.


Subject(s)
Bacteria/genetics , Gastrointestinal Microbiome/genetics , Microbiota/genetics , Nasopharynx/microbiology , Bacteria/classification , Child , Child, Preschool , Family Practice/statistics & numerical data , Female , Humans , Infant , Male , Otolaryngology , Qualitative Research , RNA, Ribosomal, 16S/genetics
4.
Diagn Microbiol Infect Dis ; 61(1): 13-20, 2008 May.
Article in English | MEDLINE | ID: mdl-18313879

ABSTRACT

Sinusitis remains 1 of the most common reasons for antimicrobial prescriptions in the United States, with health care costs approaching $4 billion annually. We utilized the serial sinus aspirate sampling (SSAS) technique to obtain daily specimens to evaluate the time course of drug effect in patients with acute maxillary sinusitis. Eighteen patients with a radiologically confirmed acute maxillary sinusitis were enrolled into a study evaluating the relationship between levofloxacin exposure and the time course of antimicrobial effect using SSAS. SSAS was performed daily during therapy for bacteriologic evaluation. Six steady-state levofloxacin concentrations were obtained. Levofloxacin plasma and sinus aspirate concentrations were modeled using Monte Carlo Parametric Expectation Maximization algorithm implemented in S-ADAPT 1.53. Endpoints evaluated included time to resolution of signs and symptoms and time to sinus sterilization. Among the 18 enrolled patients, 15 were clinically evaluable. From these, 1 Streptococcus pneumoniae, 3 Haemophilus influenzae, 1 Moraxella catarrhalis, 1 Corynebacterium spp., and 1 coagulase-negative Staphylococcus organisms were isolated, with the latter 2 organisms being likely contaminants. For the pathogens, levofloxacin MIC values ranged from 0.03 to 2 mg/L. All pathogens were eradicated by the 4th day of therapy. The median and mean time to sinus sterilization (pathogens only) was 1 and 1.4 days, respectively. The median time to resolution of each sign and symptom ranged from 1.5 to 12-19 days, with the 83% of total signs and symptoms resolved by the end of therapy (day 5). The mean plasma area under the concentration-time curve (AUC) (mg x h/L) was 100.1 (n = 14, %CV = 27). Plasma AUC/MIC ratios ranged from 33.9 to 1696 for isolated pathogens. In this pilot SSAS study, levofloxacin rapidly eradicated isolated pathogens from the maxillary sinus.


Subject(s)
Anti-Bacterial Agents/pharmacokinetics , Anti-Bacterial Agents/therapeutic use , Bacterial Infections/drug therapy , Levofloxacin , Maxillary Sinusitis/drug therapy , Ofloxacin/pharmacokinetics , Ofloxacin/therapeutic use , Adult , Bacteria/drug effects , Bacteria/isolation & purification , Bacterial Infections/pathology , Bacterial Infections/physiopathology , Female , Humans , Male , Maxillary Sinus/chemistry , Maxillary Sinus/diagnostic imaging , Maxillary Sinus/microbiology , Maxillary Sinusitis/pathology , Maxillary Sinusitis/physiopathology , Microbial Sensitivity Tests , Middle Aged , Monte Carlo Method , Peroxidase/analysis , Pilot Projects , Plasma/chemistry , Radiography , Time Factors , United States
6.
Diagn Microbiol Infect Dis ; 57(1): 105-7, 2007 Jan.
Article in English | MEDLINE | ID: mdl-17178300
7.
Laryngoscope ; 117(2): 295-8, 2007 Feb.
Article in English | MEDLINE | ID: mdl-17202908

ABSTRACT

OBJECTIVE: To define carriage of bacterial respiratory pathogens in children undergoing pressure equalization tube placement. STUDY DESIGN: Nasopharyngeal cultures were performed during tube placement. Antibiotic susceptibilities and serotypes of pneumococci were determined. RESULTS: Sixty-nine Streptococcus pneumoniae, 72 Haemophilus influenzae (41% beta-lactamase positive), and 39 Moraxella catarrhalis (all beta-lactamase positive) were isolated from 201 children. Overall, 42% of pneumococci were nonsusceptible to penicillin, and 34.8% were resistant to macrolides. In relation to the pneumococcal conjugate vaccine, 17.4% were vaccine, 31.9% vaccine-related, and 50.7% nonvaccine serotypes. CONCLUSION: Twenty-five percent of children colonized with pneumococci carried antibiotic resistant nonvaccine serotypes rarely detected before the introduction of pneumococcal conjugate vaccine, including serotype 19A isolates (7%) resistant to all oral agents tested and type 35B isolates (12%) nonsusceptible to penicillin and cefuroxime. SIGNIFICANCE: Pneumococcal colonization suggests replacement of vaccine serotypes with vaccine related and nonvaccine serotypes, many of which are resistant to common oral antimicrobials.


Subject(s)
Haemophilus influenzae/isolation & purification , Middle Ear Ventilation , Moraxella catarrhalis/isolation & purification , Nasopharynx/microbiology , Pneumococcal Vaccines , Streptococcus pneumoniae/isolation & purification , Vaccines, Conjugate , Adolescent , Anti-Bacterial Agents/pharmacology , Cefuroxime/pharmacology , Cephalosporin Resistance , Child , Child, Preschool , Drug Resistance, Bacterial , Female , Humans , Infant , Macrolides/pharmacology , Male , Otitis Media/surgery , Otitis Media with Effusion/surgery , Penicillin Resistance , Serotyping , Streptococcus pneumoniae/classification
8.
Ear Nose Throat J ; 101(9_suppl): 5S, 2022 11.
Article in English | MEDLINE | ID: mdl-36907995
9.
Pediatr Infect Dis J ; 25(2): 181-2, 2006 Feb.
Article in English | MEDLINE | ID: mdl-16462302

ABSTRACT

A 10-kg 9-month-old infant with recurrent, unresponsive otitis media presented with bilateral acute otitis media caused by Streptococcus pneumoniae type 19A, resistant to all oral agents and intermediately susceptible to ceftriaxone. Treatment with myringotomies and intramuscular ceftriaxone, 50 mg/kg/d for 5 days, was unsuccessful. The patient responded to pressure equalization tubes and local ciprofloxacin with dexamethasone drops.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Ceftriaxone/therapeutic use , Ear, Middle/microbiology , Otitis Media/drug therapy , Otitis Media/microbiology , Pneumococcal Infections/drug therapy , Streptococcus pneumoniae/drug effects , Anti-Bacterial Agents/administration & dosage , Anti-Bacterial Agents/pharmacology , Ceftriaxone/administration & dosage , Ceftriaxone/pharmacology , Cephalosporin Resistance , Humans , Infant , Injections, Intramuscular , Male , Pneumococcal Infections/microbiology , Treatment Failure
10.
Otolaryngol Head Neck Surg ; 134(1): 10-7, 2006 Jan.
Article in English | MEDLINE | ID: mdl-16399173

ABSTRACT

OBJECTIVE: Compare two dosage strengths of levofloxacin in the treatment of acute bacterial sinusitis. STUDY DESIGN AND SETTING: Multicenter clinical trial comparing levofloxacin 750 mg for 5 days vs levofloxacin 500 mg for 10 days. RESULTS: Sinus fluid samples were obtained by antral puncture (59.2%) or by sinus endoscopy (40.8%). Among microbiologically evaluable patients, 91.4% (139/152) of patients receiving levofloxacin 750 mg achieved clinical success vs 88.6% (132/149) of patients receiving levofloxacin 500 mg (95% CI -10.0, 4.2). Clinical success rates by pathogen were above 90% in both treatment groups for the 3 typical pathogens of acute sinusitis: Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis. The safety profile of the 2 dosage strengths was similar. CONCLUSION: Levofloxacin 750 mg for 5 days is noninferior to levofloxacin 500 mg for 10 days. SIGNIFICANCE: Levofloxacin 750 mg for 5 days represents a safe and effective treatment regimen for acute bacterial sinusitis. EBM RATING: A-1b.


Subject(s)
Anti-Bacterial Agents/administration & dosage , Gram-Negative Bacterial Infections/drug therapy , Gram-Positive Bacterial Infections/drug therapy , Levofloxacin , Ofloxacin/administration & dosage , Sinusitis/drug therapy , Sinusitis/microbiology , Acute Disease , Adult , Aged , Dose-Response Relationship, Drug , Double-Blind Method , Drug Administration Schedule , Female , Humans , Male , Middle Aged , Prospective Studies , Treatment Outcome
11.
Ear Nose Throat J ; 85(8): 500, 502, 504 passim, 2006 Aug.
Article in English | MEDLINE | ID: mdl-16999056

ABSTRACT

We evaluated the efficacy of a new pharmacokinetically enhanced formulation of amoxicillin/clavulanate (2,000/125 mg) twice daily for the treatment of acute bacterial rhinosinusitis (ABRS) caused by Streptococcus pneumoniae, particularly penicillin-resistant S pneumoniae (PRSP; penicillin minimum inhibitory concentrations [MICs]: > or = 2 microg/ml. A total of 2,482 patients received study medication (safety population). Of these, 2,324 were clinically evaluable (efficacy population), and 1,156 of them had at least one pathogen isolated at screening (bacteriology population). S pneumoniae was isolated from 371 patients in the bacteriology population, including 37 with PRSP. Follow-up in the bacteriology population on days 17 through 28 revealed that amoxicillin/clavulanate therapy was successful in 345 of 371 patients with S pneumoniae infection (93.0%) and in 36 of 37patients with PRSP infection (97.3%), including 7 of 8 patients (87.5%) whose amoxicillin/clavulanic acid MICs were 4/2 microg/ml or higher. Pharmacokinetically enhanced amoxicillin/clavulanate was generally well tolerated, as only 2.2% of patients withdrew because of adverse events. This agent represents a valuable new therapeutic option for the empiric treatment of ABRS, particularly in areas where antimicrobial-resistant pathogens (including beta-lactamase-positive organisms) are prevalent, and for the treatment of patients who are at increased risk of infection with PRSP.


Subject(s)
Amoxicillin/therapeutic use , Anti-Bacterial Agents/therapeutic use , Clavulanic Acid/therapeutic use , Penicillin Resistance , Sinusitis/drug therapy , Streptococcal Infections/drug therapy , Streptococcus pneumoniae/drug effects , Acute Disease , Adolescent , Adult , Aged , Aged, 80 and over , Amoxicillin/administration & dosage , Amoxicillin/pharmacology , Anti-Bacterial Agents/administration & dosage , Anti-Bacterial Agents/pharmacology , Clavulanic Acid/administration & dosage , Clavulanic Acid/pharmacology , Drug Therapy, Combination , Female , Humans , Male , Middle Aged , Risk Assessment , Sinusitis/microbiology , Streptococcal Infections/microbiology , Streptococcus pneumoniae/isolation & purification , Treatment Outcome
12.
Ear Nose Throat J ; : 145561321999277, 2021 Apr 05.
Article in English | MEDLINE | ID: mdl-33813899
13.
Clin Infect Dis ; 41 Suppl 2: S167-76, 2005 Jul 15.
Article in English | MEDLINE | ID: mdl-15942883

ABSTRACT

Episodes of acute rhinosinusitis are common among adults and are associated with a significant amount of morbidity. The symptoms of rhinosinusitis are nasal drainage, congestion, and sinus pressure. A bacterial sinus infection is more likely if these symptoms worsen after 5-7 days or do not improve after 10-14 days. The majority of bacterial episodes have been associated with Streptococcus pneumoniae and Haemophilus influenzae. In the current era of increasing resistance to beta -lactams and macrolides, treatment guidelines have been formulated worldwide to assist clinicians in the selection of antibacterials. According to one model, the following antibacterials are most likely to provide desired outcomes (90%-92% predicted clinical efficacy) for adults: respiratory fluoroquinolones (i.e., moxifloxacin, gatifloxacin, and levofloxacin), ceftriaxone, and high-dose amoxicillin-clavulanate (4 g of amoxicillin/day and 250 mg of clavulanate/day). Although the role of the fluoroquinolones in the treatment of this condition is evolving, fluoroquinolones are often recommended as second-line therapy or as first-line therapy for selected patients (e.g., those who received antibacterials in the previous 4-6 weeks or adults with moderate-to-severe disease).


Subject(s)
Anti-Bacterial Agents/therapeutic use , Aza Compounds/therapeutic use , Bacterial Infections/drug therapy , Quinolines/therapeutic use , Rhinitis/drug therapy , Sinusitis/drug therapy , Bacterial Infections/microbiology , Clinical Trials as Topic , Drug Resistance, Microbial , Fluoroquinolones/pharmacology , Fluoroquinolones/therapeutic use , Gatifloxacin , Haemophilus influenzae/drug effects , Haemophilus influenzae/isolation & purification , Humans , Levofloxacin , Meta-Analysis as Topic , Moxifloxacin , Ofloxacin/therapeutic use , Practice Guidelines as Topic/standards , Rhinitis/diagnosis , Rhinitis/microbiology , Rhinitis/physiopathology , Sinusitis/diagnosis , Sinusitis/microbiology , Sinusitis/physiopathology , Streptococcus pneumoniae/drug effects , Streptococcus pneumoniae/isolation & purification
16.
Clin Infect Dis ; 38(11): 1513-20, 2004 Jun 01.
Article in English | MEDLINE | ID: mdl-15156435

ABSTRACT

The relationship between drug exposure and the time course of antimicrobial effect at the primary infection site for acute maxillary sinusitis has not previously been explored. This single-center, open-label study quantified the time course of sinus sterilization, described gatifloxacin exposure at the infection site, and posed the hypothesis that the use of continuous and quantitative time-related end points may allow for better characterization of drug effect with fewer patients than traditional clinical trial approaches. Of the 12 enrolled patients, 10 were clinically evaluable, from whom 7 pathogens were isolated: 4 Streptococcus pneumoniae, 2 staphylococci, and 1 Enterobacter aerogenes. The median predicted 24-h area under the curve (AUC) in sinus aspirates and plasma samples was 54.7 mg x h/L and 30.1 mg x h/L, respectively. The median 24-h AUC ratio for sinus aspirates and plasma samples was 1.51 (range, 0.88-2.23). For patients infected with pneumococci, the median time to sinus sterilization was 50 h. The use of quantitative time-related end points may be useful in evaluating the efficacy of antimicrobial agents with fewer patients.


Subject(s)
Fluoroquinolones/pharmacology , Maxillary Sinusitis/drug therapy , Maxillary Sinusitis/microbiology , Acute Disease , Anti-Bacterial Agents/adverse effects , Anti-Bacterial Agents/pharmacokinetics , Anti-Bacterial Agents/pharmacology , Coagulase , Enterobacter aerogenes/drug effects , Enterobacter aerogenes/isolation & purification , Enterobacteriaceae Infections/diagnosis , Enterobacteriaceae Infections/drug therapy , Female , Fluoroquinolones/adverse effects , Fluoroquinolones/pharmacokinetics , Gatifloxacin , Humans , Male , Middle Aged , Pneumococcal Infections/diagnosis , Pneumococcal Infections/drug therapy , Staphylococcal Infections/diagnosis , Staphylococcal Infections/drug therapy , Staphylococcus/drug effects , Staphylococcus/isolation & purification , Streptococcus pneumoniae/drug effects , Streptococcus pneumoniae/isolation & purification , Treatment Outcome
17.
Am J Med ; 117 Suppl 3A: 23S-28S, 2004 Aug 02.
Article in English | MEDLINE | ID: mdl-15360094

ABSTRACT

Acute bacterial rhinosinusitis (ABRS) is a secondary bacterial infection of the nose and paranasal sinuses, usually preceded by a viral upper respiratory infection or allergy, with symptoms that have not improved after 10 days or that have worsened after 5 to 7 days. Streptococcus pneumoniae and Haemophilus influenzae are the most common causes of ABRS in adults. Increasing rates of antimicrobial resistance among S. pneumoniae and beta-lactamase production among H. influenzae are formidable challenges to the successful treatment of infections caused by these organisms. To this end, various formulations of amoxicillin-clavulanate have been developed, the most recent of which is pharmacokinetically enhanced and provides a total daily dose of 4,000 mg of amoxicillin and 250 mg of clavulanate. This formulation has been shown to be safe and effective in the treatment of infections caused by penicillin-resistant S. pneumoniae (minimum inhibitory concentration 2 microg/mL); the clavulanate component provides adequate coverage of beta-lactamase-producing pathogens.


Subject(s)
Amoxicillin-Potassium Clavulanate Combination/pharmacology , Anti-Bacterial Agents/pharmacology , Haemophilus influenzae/drug effects , Penicillin Resistance , Pneumococcal Infections/drug therapy , Rhinitis/drug therapy , Sinusitis/drug therapy , Streptococcus pneumoniae/drug effects , Acute Disease , Adult , Amoxicillin-Potassium Clavulanate Combination/therapeutic use , Anti-Bacterial Agents/therapeutic use , Drug Resistance, Bacterial , Drug Therapy, Combination/pharmacology , Humans , Rhinitis/microbiology , Sinusitis/microbiology
18.
Paediatr Drugs ; 5 Suppl 1: 25-33, 2003.
Article in English | MEDLINE | ID: mdl-14632103

ABSTRACT

In children, acute bacterial rhinosinusitis is a common infection and although rare, carries a potential for serious, life threatening complications. Bacterial rhinosinusitis usually follows a viral infection or allergic rhinitis. Early, effective antibacterial therapy is essential to shorten the duration of infection and illness, to diminish mucosal damage, and to prevent contiguous infectious involvement of the orbit or central nervous system. Because the signs and symptoms of acute bacterial rhinosinusitis are similar to those of viral upper respiratory tract infection, establishing an accurate diagnosis in children poses a clinical challenge. Infection with Streptococcus pneumoniae accounts for 30-66% of episodes of acute bacterial rhinosinusitis in children. Other important pathogens include Haemophilus influenzae (20-30%) and Moraxella catarrhalis (12-28%). In selecting initial antimicrobial therapy, priority should be given to drugs with activity against S. pneumoniae. The oral agents that currently offer the greatest activity against this pathogen include amoxicillin, amoxicillin-clavulanate, cefdinir, cefpodoxime proxetil, and cefuroxime axetil; all are considered appropriate for the initial treatment of acute bacterial rhinosinusitis in children. Amoxicillin is customarily used as first-line therapy for uncomplicated acute bacterial rhinosinusitis. For patients who are allergic to amoxicillin, second- or third-generation oral cephalosporins may be used as first-line therapy. Clarithromycin has been suggested as an alternative to amoxicillin or cephalosporins in beta-lactam allergic patients. Clindamycin may also be indicated as first-line treatment in patients who have culture-proven penicillin-resistant S. pneumoniae. If no clinical response occurs within 72 hours, the choice of a second-line antibiotic is governed by the drug's known antimicrobial efficacy, resistance patterns, dosing schedules, the potential for compliance, and knowledge of the patient's drug allergies. High-dose amoxicillin-clavulanate (90 mg/kg/d of the amoxicillin component) has been recommended for high-risk children (e.g. those in day care, and those who have recently received antibiotics) who show no improvement after treatment with the usual dose of amoxicillin (45 mg/kg/d). Broad-spectrum, third-generation oral cephalosporins, such as cefdinir, should be considered as second-line agents when standard therapy has failed or when patients show hypersensitivity to penicillin. Intramuscular ceftriaxone may be appropriate for patients who fail on a second course of antibiotic treatment.


Subject(s)
Anti-Bacterial Agents/therapeutic use , Bacterial Infections/drug therapy , Sinusitis/drug therapy , Acute Disease , Adolescent , Bacterial Infections/diagnosis , Bacterial Infections/microbiology , Child , Child, Preschool , Clinical Trials as Topic , Drug Resistance, Bacterial , Haemophilus Infections/diagnosis , Haemophilus Infections/drug therapy , Haemophilus Infections/microbiology , Haemophilus influenzae , Humans , Infant , Moraxella catarrhalis , Moraxellaceae Infections/diagnosis , Moraxellaceae Infections/drug therapy , Moraxellaceae Infections/microbiology , Sinusitis/diagnosis , Sinusitis/microbiology , Streptococcal Infections/diagnosis , Streptococcal Infections/drug therapy , Streptococcal Infections/microbiology , Streptococcus pneumoniae
19.
Clin Lab Med ; 24(2): 419-53, 2004 Jun.
Article in English | MEDLINE | ID: mdl-15177848

ABSTRACT

Antimicrobial resistance among respiratory tract pathogens represents a significant health care threat. Identifying the antimicrobial agents that remain effective in the presence of resistance, and knowing why, requires a thorough understanding of the mechanisms of action of the various agents as well as the mechanisms of resistance demonstrated among respiratory tract pathogens. The primary goal of antimicrobial therapy is to eradicate the pathogen, via killing or inhibiting bacteria, from the site of infection; the defenses of the body are required for killing any remaining bacteria. Targeting a cellular process or function specific to bacteria and not to the host limits the toxicity to patients. Currently, there are four general cellular targets to which antimicrobials are targeted: cell wall formation and maintenance, protein synthesis, DNA replication, and folic acid metabolism. Resistance mechanisms among respiratory tract pathogens have been demonstrated for all four targets. In general, the mechanisms of resistance used by these pathogens fall into one of three categories: enzymatic inactivation of the antimicrobial, prevention of intracellular accumulation, and modification of the target site to which agents bind to exert an antimicrobial effect. Resistance to some agents can be overcome by modifying the dosage regimens (e.g., using high-dose therapy) or inhibiting the resistance mechanism (e.g., b-lactamase inhibitors), whereas other mechanisms of resistance can only be overcome by using an agent from a different class. Understanding the mechanisms of action of the various agents and the mechanisms of resistance used by respiratory tract pathogens can help clinicians identify the agents that will increase the likelihood of achieving optimal outcomes.


Subject(s)
Bacterial Infections/microbiology , Drug Resistance, Bacterial/physiology , Respiratory Tract Infections/microbiology , Anti-Bacterial Agents/pharmacology , Bacteria/drug effects , Haemophilus influenzae/drug effects , Haemophilus influenzae/physiology , Humans , Moraxella catarrhalis/drug effects , Moraxella catarrhalis/physiology , Streptococcus pneumoniae/drug effects , Streptococcus pneumoniae/physiology
20.
Clin Lab Med ; 24(2): 477-502, 2004 Jun.
Article in English | MEDLINE | ID: mdl-15177850

ABSTRACT

The pharmacologic field that studies antimicrobial pharmacokinetics and pharmacodynamics (PK/PD) has had a major impact on the choice and dosing regimens used for many antibiotics especially those used in the treatment of respiratory tract infections. PK/PD parameters are particularly important in light of increasing antimicrobial resistance. Drug pharmacokinetic features, such as serum concentrations over time and area under the concentration-time curve, when integrated with minimum inhibitory concentration (MIC) values of antibiotics against pathogens, can predict the probability of bacterial eradication and clinical success. These pharmacokinetic and pharmacodynamic relationships also are important in preventing the selection and spread of resistant strains and have led to the description of the mutation prevention concentration, which is the lowest concentration of antimicrobial that prevents selection of resistant bacteria from high bacterial inocula. b-lactams are time-dependent agents without significant post-antibiotic effects, resulting in bacterial eradication when unbound serum concentrations exceed MICs of these agents against infecting pathogens for >40% to 50% of the dosing interval. Macrolides, azaolides, and lincosamides are time-dependent agents with prolonged post-antibiotic effects, and fluoroquinolones are concentration-dependent agents, resulting in both cases in bacterial eradication when unbound serum area-under-the-curve to MIC ratios exceed 25 to 30. These observations have led to changes in recommended antimicrobial dosing against respiratory pathogens and are used to assess the role of current agents, develop new formulations, and assess potency of new antimicrobials.


Subject(s)
Anti-Bacterial Agents/pharmacology , Anti-Bacterial Agents/pharmacokinetics , Respiratory Tract Infections/drug therapy , Respiratory Tract Infections/metabolism , Humans , Microbial Sensitivity Tests
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