Comparison of quantitative polymerase chain reaction, acid fast bacilli smear, and culture results in patients receiving therapy for pulmonary tuberculosis.

Quantitative-competitive polymerase chain reaction (QPCR) was performed on serial sputum samples from 22 consecutive cases of acid fast bacilli (AFB) smear-positive pulmonary tuberculosis. Of 94 specimens, 55, 72, and 83% were positive by culture, AFB smear, and QPCR, respectively. Of 52 culture-positive specimens, 6% were negative by PCR, and 13% were negative by AFB smear. Of 42 culture-negative specimens, AFB smear and QPCR were positive in 55 and 61%, respectively. AFB smear and QPCR results were strongly correlated (r = 0.75, p < 0.001), but each correlated less strongly with culture (r = 0.54, p < 0.005 for smear and r = 0.52, p < 0.005 for QPCR). When patients were classified by microbiologic response, responders tended to have less DNA in their sputum and shorter time to a negative PCR result compared to nonresponders. These data do not suggest a great advantage of QPCR over AFB smear for predicting culture results in patients with pulmonary tuberculosis.

Quantitative-competitive polymerase chain reaction for rapid susceptibility testing of Mycobacterium tuberculosis to isoniazid.

The objective of this study was to determine whether quantitative-competitive polymerase chain reaction (QC-PCR) can be used for rapid susceptibility testing of Mycobacterium tuberculosis (MTB). QC-PCR was used to determine relative amounts of mycobacterial DNA inoculated at different isoniazid (INH) concentrations. A total of six different INH-sensitive (INH-S) and five INH-resistant (INH-R) strains were inoculated in the presence of 0.0, 0.2, 1.0, and 10.0 micrograms/ml of INH. DNA was quantified using QC-PCR at Week 0 and weekly thereafter for 3 weeks. For the QC-PCR, 10-fold dilutions of control (240 bp) DNA having the same primer set as the target DNA (123 bp) were used. The amount of target DNA was estimated by using known amounts of the internal standard. For INH-S isolates there was > or = 1 log difference in DNA concentration in the presence of each INH concentration compared to that of the control within 1 to 3 weeks. In contrast, for INH-R isolates there were no apparent differences in DNA concentration between the control suspensions and those containing 0.2 and 1.0 microgram/ml INH during the 3-week incubation period. The highest INH concentration (10 micrograms/ml), however, did abolish the DNA increase seen in the other MTB suspensions. This preliminary study suggests that by using concentrations of 0.2 or 1.0 microgram/ml of INH, QC-PCR may differentiate INH-R and INH-S MTB isolates within 1 week. This method may be of particular value when applied directly to clinical specimens with varying numbers of bacilli.

Polymerase chain reaction for diagnosis of M. tuberculosis: comparison of simple boiling and a conventional method for DNA extraction.

Although the polymerase chain reaction (PCR) has been used increasingly for rapid diagnosis of tuberculosis (TB) in clinical specimens, no consensus exists regarding DNA extraction protocols. We compared a simple boiling method to a conventional, labor-intensive chemical method using lysozyme and silica particles. The boiling method was performed in less than 30 min; the chemical method required at least 6 h. A total of 82 clinical specimens (mostly respiratory) from 77 patients were obtained after routine processing from the microbiology laboratory. After DNA extraction by each method, PCR was performed to detect the 123-bp segment of IS6110, and results were compared to culture. Of 20 culture-positive specimens, 17 (85%) and 12 (60%) were positive by boiling and chemical methods, respectively. Of 62 culture-negative specimens, 61 (98%) and 57 (92%) were negative by boiling and chemical methods, respectively. The sensitivity was 100 and 92% for the boiling and chemical methods, respectively, for smears containing more than rare AFB. Our results suggest that boiling method of DNA extraction is more sensitive and no less specific than a conventional chemical method. Larger studies including a variety of clinical specimens are necessary to standardize the optimal conditions of PCR for diagnosis of M. tuberculosis.

Salmonella, Shigella, and Campylobacter: common bacterial causes of infectious diarrhea.

Salmonella, Shigella, and Campylobacter species are the most common causes of acute bacterial enteritis in the United States. These pathogens should be considered seriously in children who progress rapidly from secretory to inflammatory diarrhea syndrome or in whom diarrhea persists beyond 5 to 6 days. Furthermore, children who appear more toxic than their state of dehydration would suggest should be suspected of having an acute bacterial etiology for their diarrhea. Systemic, extraintestinal dissemination of these organisms is uncommon, with the exception of salmonella infection during the first year of life and in immunocompromised hosts. In this latter situation, culture of blood and other appropriate body fluids should be considered, along with empiric systemic antibiotic therapy. When antibiotics are warranted in patients with shigella or campylobacter infection, oral therapy is usually sufficient. Careful attention to handwashing and personal hygiene is always appropriate to prevent further spread of these organisms. The very low infectious dose of shigella infection mandates an even more compulsive attention to these latter recommendations when this organism is implicated.

Clinical profile of pediatric patients hospitalized with respiratory syncytial virus infection.

To update the clinical profile of pediatric patients hospitalized with RSV infection, we retrospectively reviewed the records of 246 children (male:female ratio 1.44:1) admitted during one season to a tertiary-care hospital. The most common admitting diagnoses were bronchiolitis (37.4%), pneumonia (32.5%), and possible septicemia (13%). Median age was 3 months; median length of stay, three days. Twice as many minorities were admitted with RSV infection as all other admissions during the same year. Family history of asthma, while common (35%), did not affect length of stay or complications. Of the 38 (15%) patients requiring intensive care, 29 (76%) underwent ventilation. Patients with underlying cardiopulmonary disease had more complications, were more likely to require intensive care (about 50%), and had significantly longer hospital stays than others. All three patients (1.2%) who died had congenital heart disease. Common risk factors included young age, chronic cardiopulmonary disease, male sex, and possibly family history of asthma. Although the most typical clinical diagnoses remain bronchiolitis and pneumonia, a systemic illness resembling the sepsis syndrome has emerged at our institution as a significant clinical presentation.

Cefprozil.

Cefprozil is a new, orally bioavailable, cephalosporin with significant activity against the bacteria commonly associated with upper and lower respiratory tract infection, and skin and soft tissue infections. Its absorption and elimination dynamics suggest once- or twice-daily dosing. The low-rate of gastrointestinal and dermatologic side effects associated with cefprozil administration suggest that it may have a significant role in the management of patients with these infections. Children with pharyngitis or urinary tract infection are more appropriately treated with antibiotics having a narrower spectrum of activity. With a variety of newer cephalosporins being marketed in the early 1990s, it will be important for the clinician to examine the data from ongoing comparative clinical trials to determine which antibiotic is best for a patient with a specific infection and whether the added cost justifies its use.

Ribavirin effect on pulmonary function in young infants with respiratory syncytial virus bronchiolitis.

To assess the effect of ribavirin on pulmonary function in infants with respiratory syncytial virus bronchiolitis, we performed a randomized (nonmatched), double blinded, placebo-controlled study of 19 infants with RSV bronchiolitis. Infants with underlying respiratory, cardiac or immunologic disease were excluded. Patients were given ribavirin (10) or placebo (9) via an aerosol generator for 18 hours/day for 3 days. Pulmonary function (dynamic compliance, total lung resistance) was calculated using a pneumotachographic method on Days 1, 2 and 7. Differences between groups on clinical criteria were not found. Approximately one-half of each group showed increased compliance and decreased lung resistance after 24 to 48 hours of therapy. By Day 7 compliance had increased 30% in the placebo group and 210% in the ribavirin-treated infants (P = 0.05). Significant differences in the rate of change of lung resistance were not seen by Day 7. We conclude that previously noted improvements in the early course of respiratory syncytial virus bronchiolitis treated with ribavirin do not appear to be a result of measurable changes in pulmonary function. However, paradoxical increases in airway resistance were not found in patients treated with ribavirin.

Cefepime. Pharmacokinetics and clinical response in patients with cystic fibrosis.

OBJECTIVE: To measure first-dose and steady-state plasma, urine, and sputum concentrations of cefepime and make preliminary assessments of the clinical efficacy of cefepime in patients with cystic fibrosis. DESIGN: Open noncomparative clinical trial. SETTING: Memorial Miller Children's Hospital of Long Beach, Calif. PARTICIPANTS: Twelve patients, aged 4 to 41 years, with a confirmed diagnosis of cystic fibrosis and chronic bronchopulmonary infections. INTERVENTIONS: Patients received cefepime at 50 mg/kg per dose (maximum dose, 2 g per dose) given intravenously every 8 hours. Clinical evaluations, pulmonary function tests, quantitative sputum cultures, and sensitivity testing were performed before, at the end of, and 2 weeks after therapy. MEASUREMENTS AND MAIN RESULTS: Mean (+/- SD) peak plasma concentrations after the first dose were 148.2 (36.6) mg/L; the following other values were included: half-life, 1.59 (0.46) hours; area under the curve, 292 (94) microgram/h per milliliter; total-body clearance, 3.01 (1.46) mL/min per kilogram; volume of distribution at steady state, 0.32 (0.10) L/kg; and percent of dose recovered in urine, 52% (27%). Steady-state and first-dose values were similar. Trough levels varied from 6.4 to 7.2 mg/L. Mean (+/- SD) sputum concentrations at steady state varied from 6.3 (5.4) to 4.8 (2.3) mg/L. At completion of therapy, nine of 10 patients' conditions were improved as indicated by clinical scores (greater than 10 points), forced vital capacity (greater than 10%), and a greater than or equal to 1 log decrease in sputum bacterial concentration. Cefepime was well tolerated in 10 patients, but rash and light-headedness developed in two patients. Pseudomonas aeruginosa minimum inhibitory concentration90 increased from the start (64 mg/L) to the end of therapy (256 mg/L) and was unchanged 2 weeks later. CONCLUSION: Based on these data and the potential advantage of a single agent for the treatment of mixed infections (Staphylococcus aureus and P aeruginosa), comparative clinical trials of cefepime and standard therapy for bronchopulmonary exacerbations in patients with cystic fibrosis appear to be warranted.

Vitamin A levels in children with measles in Long Beach, California.

Studies from Africa suggest that vitamin A supplementation may reduce morbidity and mortality rates associated with measles among poorly nourished children. We studied 20 children with measles in Long Beach, Calif., and found that 50% (95% confidence interval; 28% to 72%) were vitamin A deficient. This frequency among presumably well nourished American children supports evaluation of vitamin A status as a part of acute management of measles in the United States.

Comparison of cefprozil with other antibiotic regimens in the treatment of children with acute otitis media.

In two randomized clinical trials in children with otitis media, the efficacy and safety of cefprozil are compared to those of amoxicillin/clavulanate (n = 530) and of cefaclor and cefixime (n = 394). The rate of clinical cure or improvement was similar among patients receiving each drug regimen, ranging from 78% for amoxicillin/clavulanate to 89% for cefaclor; for cefprozil, this rate was 84% and 85% in the two studies, respectively. In the first study, cefprozil was superior to amoxicillin/clavulanate in the satisfactory clinical response rate for Streptococcus pneumoniae (P = .049), but response rates were similar for Haemophilus influenzae and Moraxella catarrhalis. Significantly more patients treated with amoxicillin/clavulanate (P less than .001) in the first study or cefixime (P less than .01) in the second study developed diarrhea than did those treated with cefprozil. We conclude that cefprozil therapy for otitis media in children produces clinical and bacteriologic response rates similar to those seen with amoxicillin/clavulanate, cefixime, or cefaclor. Furthermore, diarrhea was significantly less common with cefprozil than with cefixime or amoxicillin/clavulanate.

In vitro activity of teicoplanin compared with vancomycin against methicillin-resistant Staphylococcus aureus derived from cystic fibrosis sputum.

We evaluated the in vitro activity of teicoplanin compared with vancomycin against methicillin-resistant Staphylococcus aureus (MRSA) derived from cystic fibrosis (CF) sputum. Teicoplanin had a slightly lower median minimum inhibitory concentration (MIC) for these strains (0.25 micrograms/ml) than did vancomycin (0.5 micrograms/ml). Inoculum size increased the MICs similarly for both drugs, and pH variations did not significantly affect their activity. The presence of serum and sputum in the growth media decreased the activity of both drugs, although this was more pronounced for teicoplanin which is highly protein bound. We conclude that teicoplanin has activity against this pathogen and might be evaluated in clinical protocols designed to address this emerging clinical problem.

In vitro activity of sparfloxacin (AT-4140), a new quinolone agent, against invasive isolates from pediatric patients.

Sparfloxacin is a new oral fluoroquinolone agent with putative activity against common pediatric pathogens. Using the broth microdilution method, we evaluated sparfloxacin activity in comparison with those of other antimicrobial agents against 383 pediatric isolates derived from cultures of blood and other normally sterile body fluids. MICs were assessed in Mueller-Hinton broth, serum, and urine, as well as at inoculum sizes of 10(4) to 10(8) CFU/ml. The emergence and stability of resistance and cross-resistance of Pseudomonas aeruginosa (mucoid and nonmucoid) and Staphylococcus aureus to sparfloxacin and ciprofloxacin were evaluated. Inhibitory activity of sparfloxacin against most test organisms was within achievable serum levels. Sparfloxacin was greater than or equal to 2- to 4-fold more active than other quinolones against gram-positive pathogens and 2- to 4-fold less active than ciprofloxacin against P. aeruginosa. Sparfloxacin activity was unaffected by urine and was enhanced by two- to eightfold in human serum. Its potency was not affected by inocula of less than or equal to 10(7) CFU/ml. The frequency of development of spontaneous resistance was similar to that found for other new quinolone agents, and stable resistance emerged only in P. aeruginosa. Sparfloxacin merits additional study against invasive pediatric pathogens.

Clinical experience with aztreonam for treatment of infections in children.

The in vitro activity, pharmacokinetics, bactericidal activity, and tissue penetration of aztreonam suggest that it may play a role in therapy for serious gram-negative bacterial infections in children. Several thousand children throughout the world received aztreonam during open or comparative clinical trials for treatment of infections including pyelonephritis, bacteremia, meningitis, skeletal infection, pneumonia, and peritonitis. Cure rates have ranged from 92% to 100%, with relapses seen mainly in children with obstructive renal lesions and those with infections caused by Salmonella. A comparative trial of aztreonam for treatment of neonatal sepsis showed it to be at least as effective as amikacin for this infection. Aztreonam yielded clinical results comparable to those of conventional combined therapy for pulmonary infection in patients with cystic fibrosis. Adverse effects in pediatric trials have been uncommon; fever, diarrhea, or rash occurred in less than 2% of treated children. Reversible laboratory abnormalities have occasionally been noted. On the basis of these data, aztreonam is considered an appropriate alternative agent for the treatment of serious gram-negative bacterial infections in neonates and children. Further comparative clinical trials will delineate specific indications.

Comparative trial of cefprozil vs. amoxicillin clavulanate potassium in the treatment of children with acute otitis media with effusion.

A total of 137 children with acute otitis media with effusion were randomly allocated to treatment with cefprozil (30 mg/kg/day divided into two equal doses), an investigational cephalosporin or amoxicillin clavulanate potassium (40 mg/kg/day divided into three equal doses) for 10 days. The most common pathogens obtained from middle ear cavities by tympanocentesis were Streptococcus pneumoniae (33%), Haemophilus influenzae (19.6%) and Moraxella catarrhalis (8.3%). Patients were scheduled for follow-up visits at midtreatment, at end of therapy and at 30 days. Of the 137 children 122 were evaluable. Five of 60 patients (8.3%) treated with cefprozil and 14 of 62 patients (22.5%) treated with amoxicillin clavulanate potassium were considered therapeutic failures because of persistence of symptoms and/or isolation of the original pathogen or superinfection (P = 0.05). Rates of relapse, reinfection and persistent middle ear effusion as documented by tympanogram were comparable in both groups. When persistent middle ear effusion was analyzed by pneumatic otoscopy, 64 of 103 affected ears (62.1%) treated with cefprozil and 80 of 105 affected ears (76.1%) treated with amoxicillin clavulanate potassium were abnormal (P = 0.04). Loose stools were more common in children treated with amoxicillin clavulanate potassium than in children treated with cefprozil (P = 0.0004). Based on the efficacy results from this study, the lower gastrointestinal side effects and the convenience of twice-a-day dosing, we believe that cefprozil in a dosage of 30 mg/kg/day divided every 12 hours represents a potential alternative for the treatment of acute otitis media with effusion in children.

In-vitro activity of cefprozil (BMY 28100) and loracarbef (LY 163892) against pathogens obtained from middle ear fluid.

We compared the in-vitro activities of cefprozil, a novel oral cephalosporin, and of loracarbef, a new oral carbacephem, with other agents against middle ear fluid isolates obtained from children with acute otitis media. These included Streptococcus pneumoniae, Haemophilus influenzae and Branhamella catarrhalis. Cefprozil activity (MIC50 and MIC90) against S. pneumoniae was 0.25 and 0.50 mg/l; against H. influenzae 8 and 16 mg/l; against B. catarrhalis 2 and 2 mg/l. Loracarbef activity (MIC50 and MIC90) against S. pneumoniae was 1 and 2 mg/l; against H. influenzae 8 and 16 mg/l; against B. catarrhalis 1 and 8 mg/l. Cefprozil was four-fold more active against S. pneumoniae than loracarbef but similar to amoxycillin, amoxycillin/clavulanate, cefaclor, cefixime, cefuroxime and trimethoprim/sulfamethoxazole (TMP/SMX). Against H. influenzae, cefprozil was similar to loracarbef and other agents through less active than TMP/SMX and cefixime. Against B. catarrhalis, cefprozil was four-fold more active than loracarbef, cefaclor and cefixime but similar to the comparative antibiotics. Cefprozil and loracarbef activities were unaffected at pH 6 and 8 or in the presence of human serum, but there was a major diminution of activity for both agents at pH 5 and at inoculum sizes greater than or equal to 10(7) cfu/ml. Cefoprozil and loracarbef have consistent activity against middle ear pathogens and further pharmacokinetic and clinical studies appear warranted.