Sinus Aspirates Research Articles

Immune response to Fusobacterium nucleatum and Prevotella intermedia in patients with chronic maxillary sinusitis.

Our objective was to study the immune response to 2 anaerobic bacteria in patients with chronic maxillary sinusitis. Immunoglobulin G class antibody titers to Fusobacterium nucleatum and Prevotella intermedia were measured by enzyme-linked immunosorbent assay. Serum levels in the patients were determined on the day sinus aspiration for culture was done, and 75 to 90 days later, after completion of antimicrobial therapy, Prevotella intermedia was isolated from 16 aspirates, and F. nucleatum from 12. Median antibody levels at day 1 for F. nucleatum and P. intermedia were significantly higher in patients whose serum aspirates harbored these organisms than at days 75 to 90 in those who were cured (p < .05). However, the levels stayed elevated in the 5 patients who did not improve. The elevated antibody levels to F. nucleatum and P. intermedia, known oral pathogens, suggest a potential pathogenic role for these organisms in chronic maxillary sinusitis.

Alternative to endoscopic sinus surgery in the management of pediatric chronic rhinosinusitis refractory to oral antimicrobial therapy

We determined the safety, feasibility, and efficacy of a treatment regimen consisting of maxillary sinus aspiration and irrigation with or without adenoidectomy, followed by culture-directed intravenous antibiotics and oral prophylaxis, for children with chronic rhinosinusitis refractory to oral antimicrobial therapy. Twenty-seven children (age 1–12 years, mean 6.7 years) with symptomatic (mean duration 16 months) and computed tomography-proven sinus disease, which persisted despite at least 1 month of oral antibiotics, were treated. Twenty-four patients (89%) had complete resolution of their presenting symptoms after intravenous therapy; in 3 (11%), intravenous therapy failed and endoscopic sinus surgery was required. Follow-up data were available for 26 of the children (96%); 23 of them had initial complete resolution. At last follow-up (mean 282 days, range 26–1095 days), 10 of these 23 patients (44%) remained asymptomatic, and 13 (57%) had had at least one other episode of sinusitis (mean 1.0, range 1–3) treated with oral antibiotics, with resolution. Treatment-related complications included superficial thrombophlebitis (7%), diarrhea (7%), intravenous catheter guide-wire kink requiring venotomy (4%), and serum sickness–like syndrome (4%). These preliminary results suggest that this treatment plan is relatively safe and feasible and that it may be a reasonable alternative to endoscopic sinus surgery in children with chronic rhinosinusitis unresponsive to orally administered antimicrobial therapy. (Otolaryngol Head Neck Surg 1999;120:219-24.)

Azithromycin versus amoxicillin/clavulanate in the treatment of acute sinusitis

Purpose: To compare the efficacy and tolerability of a 3-day course of azithromycin with a 10-day course of amoxicillin/clavulanic acid in the treatment of acute sinusitis in adults. Patients and Methods: One hundred adult patients with acute sinusitis were included in an open, randomized study. Clinical diagnosis of sinusitis was confirmed by nasal endoscopy, sinus radiography, and (when possible) by culture of sinus aspirate. Patients were randomized to receive azithromycin (500 mg once daily for 3 days) or amoxicillin/clavulanate (625 mg every 8 hours for 10 days). Results: A significantly faster resolution of signs and symptoms of sinusitis was observed in the azithromycin-treated patients. By the end of therapy (days 10–12), 95% of the patients in the azithromycin group and 74% in the amoxicillin/clavulanate group were cured. The remaining patients' conditions were improved. By the follow-up visit, cure was achieved in 98% of the azithromycin-treated patients, and 91 % of the amoxicillin/clavulanate-treated patients. Treatment failure was observed in three patients from the amoxicillin/clavulanate group, and relapse occurred in one patient from each group. Bacteriologic eradication was achieved in 23 of 23 and 21 of 24 patients treated with azithromycin and amoxicillin/clavulanate, respectively. Both drugs were well tolerated. Two patients (4%) from the azithromycin group and five patients (10%) from the amoxicillin/clavulanate group reported mild gastrointestinal disturbances. Conclusions: In adults with acute sinusitis, a 3-day course of azithromycin was as effective and well tolerated as a 10-day course of amoxicillin/clavulanic acid. A significantly simpler dosage regimen and faster clinical effect were the advantages of azithromycin.

Sinusitis in neurologically impaired children

The microbiologic features of infected sinus aspirates in nine children with neurologic impairment were studied. Anaerobic bacteria, always mixed with aerobic and facultative bacteria, were isolated in 6 (67%) aspirates and aerobic bacteria only in 3 (33%). There were 24 bacterial isolates, 12 aerobic or facultative and 12 anaerobic. The predominant aerobic isolates were Klebsiella pneumoniae, Escherichia coli, and Staphylococcus aureus (2 each) and Proteus mirabilis, Pseudomonas aeruginosa, Haemophilus influenzae, Moraxella catarrhalis, and Streptococcus pneumoniae (1 each). The predominant anaerobes were Prevotella sp. (5), Peptostreptococcus sp. (4), Fusobacterium nucleatum (2), and Bacteroides fragilis (1). β-Lactamase–producing bacteria were isolated from 8 (89%) patients. Organisms similar to those recovered from the sinuses were also isolated from tracheostomy site and gastrostomy wound aspirates in five of seven instances. This study demonstrates the uniqueness of the microbiologic features of sinusitis in neurologically impaired children, in which, in addition to the organisms known to cause infection in children without neurologic impairment, facultative and anaerobic gram-negative organisms that can colonize other body sites are predominant. (Otolaryngol Head Neck Surg 1998;119:357-60.)

Diagnosis and management of sinusitis in children

Acute bacterial sinusitis is a common clinical problem. The usual predisposing events are either viral upper respiratory infection or allergic inflammation. Patients present with either persistent or severe respiratory symptoms. Subacute and chronic sinusitis are characterized by very protracted respiratory symptoms that include nasal discharge, cough, or both. A precise diagnosis of bacterial sinusitis is made when sinus aspiration is performed and yields pus and bacteria in high colony count. Images, either plain radiographs or computer tomographic scans, can be used to confirm the diagnosis of bacterial sinusitis in patients whose signs and symptoms suggest the diagnosis. Streptococcus pneumoniae, Haemophilus influenzae , and Moraxella catarrhalis are the usual pathogens retrieved from patients with acute, subacute, and recurrent acute sinusitis. These same pathogens cause acute exacerbations of chronic sinusitis. In patients with chronic persistent sinusitis, the role of bacterial agents is less clear. The prescription of antimicrobials is the backbone of the medical management of acute bacterial sinusitis. Clinical improvement is prompt in nearly all children treated with an appropriate agent.

Microbiology of nosocomial sinusitis in mechanically ventilated children.

To assess the bacteriology of nosocomial sinusitis in mechanically ventilated children. Retrospective review of sinus aspirate specimens obtained from 20 children with nosocomial sinusitis. The specimens were processed for aerobic and anaerobic bacteria. A total of 58 isolates (2.9 per specimen), 30 aerobic or facultative (1.5 per specimen) and 28 anaerobic (1.4 per specimen), were recovered. Aerobes only were present in 8 patients (40%), anaerobes only in 5 (25%), and mixed aerobic and anaerobic flora in 7 (35%). The predominant aerobes were Pseudomonas aeruginosa (6 isolates), Staphylococcus aureus (5 isolates), Escherichia coli (3 isolates), and Klebsiella pneumoniae (3 isolates). The predominant anaerobes were Peptostreptococcus species (8 isolates), Prevotella species (6 isolates), and Fusobacterium species (4 isolates). Forty-one beta-lactamase bacteria were recovered from 14 specimens (70%). Thirty isolates similar to the sinus isolates were also recovered from the trachea, 6 from blood culture specimens, and 6 from other sites. Anaerobes were more commonly isolated from sinus aspirate samples obtained after 18 days of mechanical ventilation (21 vs 7, P<.05 by chi2). This study demonstrates the polymicrobial aerobic-anaerobic flora of nosocomial sinusitis in mechanically ventilated children.

Endoscopically guided sinonasal cultures: A direct comparison with maxillary sinus aspirate cultures

Endoscopically guided sinonasal cultures: A direct comparison with maxillary sinus aspirate cultures

Endoscopically Guided Sinonasal Cultures: A Direct Comparison with Maxillary Sinus Aspirate Cultures

Endoscopically Guided Sinonasal Cultures: A Direct Comparison with Maxillary Sinus Aspirate Cultures

Comparative Efficacy and Tolerability of Clarithromycin and Cefaclor in the Treatment of Outpatients with Acute Maxillary Sinusitis

The primary objective of this open, randomised study was to compare the efficacy and tolerability of clarithromycin (500mg twice daily) and cefaclor (500mg 3 times daily) administered for 10 days in the treatment of acute nonodontogenic maxillary sinusitis in adults. Tolerability and efficacy were assessed during therapy (by phone), post-treatment, and at follow-up (30 to 45 days after completion of therapy). Additionally, pretreatment sinus aspirates were cultured to determine which pathogens commonly cause sinusitis in southern Greece. Pathogens most commonly isolated were Streptococcus pneumoniae, 49%; Haemophilus species, 14%; Staphylococcus aureus, 10%; S. pyogenes, 10%; and Moraxella (Branhamella) catarrhalis, 10%. Of the 93 outpatients enrolled, 48 received clarithromycin and 45 received cefaclor, and both agents demonstrated equivalent clinical efficacy, with post-treatment clinical success rates (cure or improvement) of 92.5 and 91.4%, respectively. Both drugs were associated with equivalent recurrence rates at follow-up (15 and 13%, respectively) and tolerability parameters were also comparable, although clarithromycin was associated with a significantly higher incidence of taste perversion than cefaclor (11 vs 2%, p < 0.05) and cefaclor was associated with a higher incidence of skin rash than clarithromycin (7 vs 0%, p < 0.05). Clarithromycin and cefaclor are both well tolerated and effective in the treatment of acute maxillary sinusitis in adults.

Bacterial Findings in Acute Maxillary Sinusitis—European Study

Bacteriology of acute maxillary sinusitis was studied in 569 patients in 16 centers of 6 countries located throughout Europe during 1992–1994 by ENT specialists. Patients with symptoms of acute sinusitis lasting less than 3 weeks with ongoing purulent nasal discharge were included. Diagnosis was verified by sinus x-ray or ultrasonography and a positive aspiration finding in maxillary sinus puncture. One or more pathogens were isolated from the maxillary sinus aspirates of 375 (66%) patients. Fifty-six percent of patients harboured 1 pathogen and 10% multiple pathogenic organisms, respectively. Haemophilus influenzae was the most common pathogen isolated (148 isolates), occurring as a single pathogen in 14% of the patients. The occurrence of H. influenzae was highest in Finnish military hospital patients (43–48%), as compared with the non-military Finnish patients (9–11%) or to patients from other European centers (mean 13%). H. influenzae was more frequently β-lactamase positive in other European centers (22%) than in Finnish centers (7%). Streptococcus pneumoniae was the most common pathogen isolated in other European centers (20%) but second most common in Finnish centers (13%). Moraxella catarrhalis occurred at quite similar frequency among Finnish centers (9–140%), but clearly less often in other centers (mean 4%). S. aureus, which in acute maxillary sinusitis is regarded as a contaminant from the nasal cavity, was more prevalent in other European centers (12%) than in Finnish centers (4%). In patients with acute maxillary sinusitis reliable bacteriological samples should be taken by antral aspiration directly from the diseased sinus.

Microbiology of the Maxillary Sinus in Adults with Chronic Sinus Disease

Antimicrobial therapy is a part of the care of patients with chronic sinus disease (CSD), but the etiologic role of microorganisms in this condition is unclear. Twenty patients with CSD undergoing functional endoscopic sinus surgery who had been off antibiotics for at least 1 week before surgery had a maxillary sinus aspirate for quantitative culture for aerobic bacteria and fungi and a semiquantitative culture from the antrostomy of the same maxillary sinus during endoscopic surgery. Six (30%) of the patients had infection of the maxillary sinus diagnosed by the presence of ≥ 103cfu/mL of organisms in the sinus aspirate (Haemophilus influenzae in two patients and one patient each with Moraxella catarrhalis, α-streptococcus, mixed oropharyngeal flora, or Alternaria sp.). All antrostomy specimens obtained by nasal endoscopy during surgery were positive, but the antrostomy cultures did not correlate with the sinus aspirate cultures from the same sinus. Staphylococcus aureus and/or Gram negative rods in eight antrostomy cultures did not predict the presence of these pathogens in any of the maxillary sinus aspirates. Conversely, the bacteria detected with the quantitative aspirate culture in five of the six infected sinuses were not found in the antrostomy specimen; only the fungal sinus infection correlated with the antrostomy culture. Infection of the maxillary sinuses occurred in patients with both limited and severe disease by CT imaging. About one third of patients with CSD necessitating surgery had microbial infection of the maxillary sinus, but antrostomy cultures obtained via endoscopy did not predict the organisms infecting the sinus.

Sinusitis in mechanically ventilated patients and its role in the pathogenesis of nosocomial pneumonia.

Nosocomial sinusitis is a complication of endotracheal intubation and mechanical ventilation in critically ill patients. Its incidence is often underestimated because of a lack of clinical signs. It is suspected in patients with nasal discharge or unexplained fever. Its diagnosis is based on radiological examination, by radiograph or computed tomography scan, and microbiological cultures of maxillary sinus aspirate. Maxillary sinusitis is often associated with involvement of the sphenoid, ethmoid, and/or frontal sinuses. Its incidence varies greatly according to diagnostic criteria and the population studied. Infectious sinusitis is less frequent than noninfectious sinusitis, occurring in 20 to 30% of patients intubated for at least seven days. Its incidence is higher in nasotracheally than in orotracheally intubated patients. Other risk factors include nasogastric tubes and head trauma. The main causative agents are gram-negative bacilli, primarily Pseudomonas aeruginosa, Acinetobacter baumannii, and Enterobacteriaceae, but Staphylococcus aureus and yeasts are also common. Patients with nosocomial sinusitis are more likely to develop pneumonia than those without sinusitis. The sinus provides a bacterial reservoir from which organisms may seed the tracheobronchial tree. The association of sinusitis and pneumonia is mainly due to Staphylococcus aureus, Pseudomonas aeruginosa, and Acinetobacter baumannii. The treatment of sinusitis is based on the removal of all nasal tubes, topical decongestants, and maxillary sinus drainage and lavage. The role of intravenous antibiotics is controversial.

Bacteriology and beta-lactamase activity in acute and chronic maxillary sinusitis.

To assess the bacteriology and beta-lactamase enzyme activity in aspirates of 10 acutely and 13 chronically inflamed maxillary sinuses. The predominant organisms isolated in acute sinusitis were Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis, and those found in chronic sinusitis were Prevotella species, Fusobacterium species, and Peptostreptococcus species. Four beta-lactamase-producing organisms (BLPOs) were isolated in four specimens (40%) obtained from acutely inflamed sinuses, and 14 BLPOs were recovered from 10 chronically inflamed sinuses (77%). The predominant BLPOs in acute sinusitis were H influenzae, and M catarrhalis; those in chronic sinusitis were Staphylococcus aureus, Prevotella species, Fusobacterium species, and Bacteroides fragilis. Beta-lactamase activity was detected in 12 (three in acute and nine in chronic sinusitis) of the 14 aspirates that contained BLPOs. The detection of beta-lactamase activity in sinus aspirates provides support for the role of BLPOs in the failure of penicillin therapy in sinusitis.

Evaluation of maxillary sinus aspiration in patients with fever of unknown origin.

The value of diagnostic maxillary sinus aspiration in patients with abnormal findings on sinus radiographs and fever of unknown origin is unclear. To better define indications for this procedure, the results of 51 sinus aspirations in 34 patients with fevers of unknown origin and abnormal findings on sinus radiographs were analyzed retrospectively. Results of aerobic and anaerobic cultures were evaluated in the context of clinical signs and symptoms at the time of the maxillary sinus puncture. Typical symptoms of paranasal sinus disease were found to be the best predictor of a positive culture. Of patients with sinusitis complaints, 86.4% had culture-positive aspirations, whereas only 8.3% of patients without clinical symptoms of sinusitis had culture-positive aspirations. This study indicates that symptoms of sinus disease play an important role in determining the benefit of sinus aspiration in this group of patients.

Twice-daily dosing of loracarbef 200 mg versus 400 mg in the treatment of patients with acute maxillary sinusitis

Loracarbef is an oral synthetic betalactam antibiotic in the new carbacephem class. We conducted a multicenter, randomized, double-blind, parallel-group study to compare the efficacy and safety of loracarbef 200 mg twice daily (BID) and 400 mg BID when given orally for 10 days to patients 12 years of age and older with acute maxillary sinusitis. Because sinus aspirates for culture are not routinely obtained in the management of acute maxillary sinusitis, antimicrobial therapy usually is selected empirically. This study was designed to provide data simulating the usual clinical practice of treatment without sinus aspiration. Two hundred nine patients who met the entry criteria, which included abnormal pretherapy sinus radiographs compatible with acute maxillary sinusitis and symptoms of fewer than 4 weeks' duration, qualified for the clinical analyses. Of the 106 clinically qualified patients assigned to the 200-mg BID group, favorable clinical responses (cure and improvement) were noted in 86 (81.1%) patients. Of the 103 clinically qualified patients assigned to the 400-mg BID group, 84 (81.6%) patients had favorable clinical responses. These results compare favorably with accepted clinical response rates of 70% to 80% for beta-lactams selected on an empiric basis. At the end of the treatment period, favorable radiologic responses (resolved and improved) and favorable clinical responses occurred in 55 (51.9%) of the 106 clinically qualified patients in the 200-mg BID group and in 57 (55.3%) of the 103 clinically qualified patients in the 400-mg BID group. Mean roentgenogram scores for the clinically qualified patients were 2.3 for both groups before therapy and 1.3 and 1.5 after therapy for the 200-mg BID and 400-mg BID groups, respectively. The mean change from pretherapy to posttherapy by patient was 1.0 for the 200-mg BID group and 0.8 for the 400-mg BID group. There were no statistically significant differences between treatment groups in the incidence of specific adverse events reported during therapy. These data suggest that loracarbef 200 mg BID is comparable in efficacy and safety to loracarbef 400 mg BID in the treatment of patients with acute maxillary sinusitis.

Maxillary sinusitis in the surgical intensive care unit: A study using bedside sinus ultrasound

Purpose: This study investigates the incidence of acute maxillary sinusitis (AMS) in the surgical intensive care unit (SICU). Methods: One hundred consecutive patients admitted to the SICU were examined in a prospective observational mode. Bedside sinus ultrasound (SUS) was performed on admission and every 48 hours. Patients with sinus fluid by SUS and unexplained sepsis underwent confirmatory sinus aspiration. Results: The development of fluid in the maxillary sinus was identified in 15 patients by SUS. Acute maxillary sinus occurred in only 1 (1%). Conclusion: This study shows SUS to be a simple, efficient method for determining the presence of maxillary sinus fluid in the SICU. Acute maxillary sinus was an unusual finding. Our policy of avoidance of nasal instrumentation may have contributed to the low incidence of AMS in this high-risk patient population.

Causes of Fever and Pulmonary Densities in Patients with Clinical Manifestations of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia, a leading cause of sepsis in patients with acute respiratory failure, is difficult to distinguish clinically from other processes affecting patients receiving mechanical ventilation. We conducted a prospective study of patients with suspected ventilator-associated pneumonia to identify the causes of fever and densities on chest radiographs and to evaluate the diagnostic yield and efficiency of tests used alone and in combination. The 50 patients entered into the study underwent a systematic diagnostic protocol designed to identify all potential causes of fever and pulmonary densities. Diagnoses responsible for fever were established by strict diagnostic criteria for 45 of the 50 patients. The prevalence of specific conditions and diagnostic yield of individual tests were used to formulate a simplified diagnostic protocol. The diagnostic protocol identified 78 causes of fever (median 2 per patient). Infections were the leading causes of fever and pulmonary densities. Of the 45 patients with fever, 37 had one or more infections identified (67 sources). Most infections (84 percent) were one of four types:pneumonia, sinusitis, catheter-related infection, or urinary tract infection. Ventilator-associated pneumonia occurred in only 42 percent. All but nine infections (87 percent) were directly or indirectly related to insertion of a catheter or a tube. Concomitant infections were frequent (62 percent), particularly in patients with sinusitis (100 percent), catheter-related infections (93 percent), and pneumonia (74 percent). Of concomitant infections, 60 percent were caused by a different pathogen. Noninfectious causes of fever were more common in the 22 patients with adult respiratory distress syndrome. Histologically proved pulmonary fibroproliferation was the only cause of fever in 25 percent of patients with adult respiratory distress syndrome. Radiographic densities were caused by an infection in only 20 patients (19 pneumonia, 1 empyema). In more than 50 percent of the 25 patients without adult respiratory distress syndrome, congestive heart failure, and atelectasis were the sole causes of pulmonary densities, and fever always originated from an extrapulmonary site of infection. Used in combination, bronchoscopy with protected sampling, computed tomographic scan of the sinuses, and cultures of maxillary sinus aspirate, central intravenous or arterial lines, urine, and blood identified 58 of the 78 sources of fever (74 percent). The observations in this study document the complex nature of acute respiratory failure and fever and underscore the need for accuracy in diagnosis. The frequent occurrence of multiple infectious and noninfectious processes justifies a systematic search for source of fever, using a comprehensive diagnostic protocol. A simplified diagnostic protocol was devised based on the diagnostic value of individual tests.

Sinus Aspirates and Radiographic Abnormalities in Severe Attacks of Asthma

We evaluated the occurrence of abnormalities in paranasal sinus radiographs in acute asthma by taking a radiograph of the sinuses of 110 consecutive patients admitted to a medical ward a total of 149 times for asthma. Maxillary sinus infection was assessed by taking aspirate from radiologically abnormal maxillary sinuses. An abnormal finding in any paranasal sinus was detected on 87% (130 of 149) of admissions and the yield of maxillary aspirate was macroscopically mucous, purulent or mucopurulent in 60% (42 of 70) of aspirates. A positive bacteriological culture was obtained from 23 aspirates and a virus was detected in 15, there being 7 aspirates in which both a bacterium and a virus could be detected. Although the correlation between radiographic findings and the aspirates was not very close we conclude that radiographic abnormalities of the paranasal sinuses are common in acute asthma as are infections of maxillary sinuses with an abnormal radiographic finding. There is an obvious need to look for sinusitis when a patient with an exacerbation of asthma is being evaluated.

Diagnosis of intestinal and disseminated microsporidial infections in patients with HIV by a new rapid fluorescence technique.

To assess the value of a new rapid fluorescence method for the diagnosis of microsporidiosis in HIV seropositive patients. Microsporidian spores in stools were demonstrated by using the fluorochrome stain Uvitex 2B. The new technique was evaluated in three groups of HIV seropositive patients with diarrhoea. Group 1: 19 patients with biopsy confirmed E bieneusi infection (186 stool samples); group 2: 143 consecutive patients from whom faeces were submitted for routine investigation of diarrhoea (318 samples); group 3: 16 patients with small intestinal biopsy specimens negative for microsporidia (55 samples). The new method was used to monitor spore shedding during experimental treatment with paromomycin and albendazole in four patients. Brightly fluorescent spores were detected in all stool samples of patients in group 1. In group 2 16 (11%) patients had spores in their stool samples. E bieneusi was found in 11 patients; in the other five another genus of microsporidia, Encephalitozoon, was recognised. Encephalitozoon spores were also found in the urine of three of these patients and in the maxillary sinus aspirate of two of them, suggesting disseminated infection. The results were confirmed by electron microscopic examination. In group 3 negative biopsy specimens were confirmed by negative stool samples in all cases. Treatment with albendazole and paromomycin did not affect the spore shedding in three patients with E bieneusi infection. By contrast, in a patient with Encephalitozoon sp infection albendazole treatment resulted in clinical improvement together with complete cessation of spore excretion in the stool. The Uvitex 2B fluorescence method combines speed, sensitivity, and specificity for the diagnosis and treatment evaluation of intestinal and disseminated microsporidiosis.

Cefaclor vs amoxicillin in the treatment of acute, recurrent, and chronic sinusitis

The treatment of acute, recurrent, and chronic sinusitis remains controversial because of the presence of a wide variety of aerobic and anaerobic bacteria in the sinuses. This double-blind, randomized trial compared cefaclor with amoxicillin in the treatment of acute, recurrent, and chronic maxillary sinusitis using clinical evaluation, roentgenography, and microbiologic evaluation of antral aspirates. Outpatient office of five otorhinolaryngologists in Salt Lake City, Utah. One hundred eight adult patients with acute, recurrent, or chronic maxillary sinusitis. Oral treatment with cefaclor (500 mg) twice daily or amoxicillin (500 mg) three times daily for 10 days. Clinical response to treatment with cefaclor vs amoxicillin. Fifty-six patients with acute sinusitis, 25 with recurrent sinusitis, and 15 with chronic sinusitis were evaluable. Although multiple organisms were common in each group, patients with acute sinusitis were more likely to have Haemophilus influenzae or Streptococcus pneumoniae, and patients with recurrent or chronic sinusitis were more likely to have anaerobes in sinus aspirate. Whether treated with cefaclor or amoxicillin, clinical improvement occurred in 86% of patients with acute sinusitis and 56% of patients with recurrent sinusitis. Patients with chronic sinusitis were too few to allow statistical analysis of the differences in outcome between them and patients with recurrent or acute sinusitis. Resistance of the cultured organisms to the study drug used was unrelated to treatment outcome. The rate of clinical improvement was high in patients with acute sinusitis but was less favorable in those with recurrent and chronic disease regardless of the study drug used. The susceptibility of organisms isolated to the study drugs was unrelated to outcome.