[Evaluation of in vitro activity of pristinamycin against Haemophilus influenzae]

The activity of pristinamycin against H. influenzae was evaluated using various in vitro tests. Minimal inhibitory concentrations (MICs) were determined by an agar dilution method. The range of MICs was from 0.25 mg/l to 8 mg/l. MIC 50 was 2 mg/l; MIC 90 was 4 mg/l. The activity of component pristinamycin II (PII) is similar to that of pristinamycin and superior to that of component pristinamycin I (PI). Minimal bactericidal concentrations (MBCs) were equal to or two times higher than MICs. Killing curves showed a bactericidal activity obtained after 6 hours at MIC x 2 and MIC x 4 of pristinamycin. Component PII exhibited a bactericidal activity at MIC x 4. The post-antibiotic effect was high with pristinamycin: after two hours of contact with the antibiotic, PAEs were 2 hours with 1 mg/l, from 4 to 6.8 hours with 2 mg/l, and 6.7 hours with 4 mg/l. The PAEs with component PII were from 1 hour to 2 hours at concentrations of 1, 2, or 4 mg/l. Antibiotic resistance to various antibiotics did not influence the antibacterial activity of pristinamycin. At a breakpoint < or = 2 mg/l, more than 85% of the strains were sensitive to pristinamycin. The unimodal distribution of the strains showed the lack of acquired resistance to pristinamycin in these bacterial species.

[Study of susceptibility of Haemophilus influenzae to antibiotics (other than beta-lactams) by using HTM gelose (Haemophilus test medium)]

HTM agar was used for in vitro study for antibiotics activity (other than beta-lactams) on H. influenzae. Tested strains belong to various phenotypes. The zone-size breakpoints were determined according to breakpoints concentrations, distribution of bacterial populations and mechanism of resistance. The following zone-size breakpoints could be suggested: chloramphenicol (30 micrograms) > or = 28 and < 24 mm; kanamycin (30 UI) > or = 18 and < 15 mm; gentamicin (10 UI) > or = 16 and < 14 mm; tetracycline (30 UI) > or = 23 and < 18 mm; doxycycline (30 UI) > or = 20 and < 14 mm; minocycline (30 UI) > or = 20 mm; rifampicin (30 micrograms) > or = 24 and < 20 mm; pristinamycin (15 micrograms) > or = 20 mm; erythromycin (15 UI) > or = 22 and < 18 mm; ciprofloxacin (5 micrograms) > or = 30 mm; trimethoprim and co-trimoxazole > or = 24 and < 20 mm.

[Study of susceptibility of Haemophilus influenzae to beta-lactams by using HTM gelose (Haemophilus test medium)]

HTM agar was used for in vitro study of bêta-lactam antibiotics activity on H. influenzae. Tested strains belong to the three ampicillin phenotypes: sensitive, betalactamase production and ampicillin resistance without production of betalactamase. Using 2 micrograms ampicillin disk, diameters > or = 20 mm and < 20 mm separate ampicillin sensitive and resistant strains. The following zone-size breakpoints could be suggested: ampicillin (10 micrograms) > or = 25 and < 22 mm; amoxicillin (25 micrograms) > or = 26 mm and < 23 mm; ampicillin/sulbactam (10/10 micrograms) > or = 25 mm and < 22 mm; amoxicillin/clavulanic acid (20/10 micrograms) > or = 26 mm and < 23 mm; cefaclor (30 micrograms) > or = 25 mm and < 20 mm; cefuroxime (10 micrograms) > or = 22 mm and < 19 mm; cefixime (10 micrograms) and cefpodoxime (10 micrograms) > or = 26 mm; cefotaxime (30 micrograms) et ceftriaxone (30 micrograms) > or = 30 mm. The zone-size breakpoints concentrations, distribution of bacterial populations, mechanisms of resistance. In vitro study may screen for ampicillin resistance mechanisms.

Tentative criteria for confirming the in vitro susceptibilities of Haemophilus influenzae and Neisseria gonorrhoeae to two fluoroquinolones (sparfloxacin and levofloxacin), including quality control parameters

Sparfloxacin and levofloxacin were evaluated against 150 Haemophilus influenzae isolates and 149 Neisseria gonorrhoeae isolates in order to define susceptibility testing parameters. Sparfloxacin-susceptible H. influenzae strains were defined as those for which the MICs were < or = 0.25 microgram/ml and the zones were > or = 30 mm, and N. gonorrhoeae susceptible strains were those for which the MICs were < or = 0.03 microgram/ml and the zones were > or = 39 mm (5-micrograms disks). Levofloxacin-susceptible strains of H. influenzae included those for which the MICs were < or = 0.12 microgram/ml and the zones were > or = 32 mm and N. gonorrhoeae susceptible strains were those for which the MICs were < or = 0.12 microgram/ml and the zones were > or = 37 mm (5-micrograms disks). Criteria for a resistant category cannot yet be defined for either quinolone. In multilaboratory studies with different lots of Haemophilus Test Medium, replicate tests with the standard control strain of H. influenzae (ATCC 49247) were evaluated. For sparfloxacin disk tests, the proposed zone size limits were 33 to 42 mm and broth microdilution MIC limits were 0.004 to 0.016 microgram/ml, whereas for levofloxacin tests, zone size limits were 32 to 41 mm and broth microdilution MIC limits were 0.008 to 0.03 microgram/ml. Other multilaboratory studies evaluated tests with supplemented GC agar and N. gonorrhoeae ATCC 49226; for both drugs, zone size limits were 44 to 52 mm and agar dilution MIC limits were 0.004 to 0.016 microgram/ml.

[The bactericidal effect of oxybuprocaine. A possible cause of false negative results in bronchoalveolar lavage]

New approaches in the diagnosis of pneumonia, especially in intensive care units, are quantitative cultures of bronchoalveolar (BAL) fluid or the protected specimen brush. The sensitivity of these methods, however, has often been found to be as low as 50-60%. One possible explanation for the low sensitivity of these diagnostic tools is the antimicrobial activity of local anaesthetics used in bronchoscopy. Therefore, we investigated the bactericidal properties of oxybuprocaine, a topical anaesthetic used for bronchoscopy in our clinic, in order to test the reliability of specimens obtained from BAL. METHODS. The bactericidal activity of oxybuprocaine in concentrations of 1%, 0.1%, 0.05% and 0.01% was tested by constructing time-kill curves for Streptococcus pneumoniae, Hemophilus influenzae, Pseudomonas aeruginosa and Escherichia coli. Five stains of each bacterial species were tested. The inoculum size was 10(4) ml, and bacteria were counted after 10, 20, 30, 60 and 120 min. RESULTS. The resulting time-kill curves are demonstrated in Figs. 1-4. The most sensitive bacteria were S. pneumoniae and H. influenzae, in which significant bactericidal activity could be shown even with a 0.01% solution of oxybuprocaine. E. coli and P. aeruginosa were also inhibited, but only at the highest concentration of 1%. CONCLUSIONS. The use of local anaesthetics before material is taken for culture, e.g. from BAL, may give rise to false-negative results and should therefore be avoided or reduced. For each local anaesthetic used in bronchoscopy, the concentrations that can be used without the risk of false-negative results should be determined.

Beta-lactam susceptibility of Haemophilus influenzae strains showing reduced susceptibility to cefuroxime

Minimum inhibitory concentrations of 13 beta-lactam antibiotics (ampicillin, amoxycillin, amoxycillin/clavulanate, imipenem, cefazolin, cefadroxil, cefaclor, cefuroxime, cefotaxime, cefepime, cefpirome, cefpodoxime and cefixime), were determined for 76 strains of beta-lactamase negative Haemophilus influenzae, isolated over a five year period (1985-1990) that gave reduced zones to cefuroxime on disc testing when compared to the control strain H. influenzae NCTC 11931. MIC90 values for all antibiotics (except imipenem) were approximately ten times higher than the MIC90 values for a susceptible control group. Increased resistance was not associated with any particular biotype, although three biotype III strains were highly resistant to imipenem. More than 50% of strains with reduced susceptibility to beta-lactam antibiotics were isolated from patients with chronic respiratory disease. Published data on the sputum concentration of each antibiotic were compared to the MIC90 values obtained for the susceptible and resistant strains.

[Antimicrobial activity of amoxicillin versus amoxicillin/clavulanic acids. In vitro study against S aureus, H influenzae and A baumanii strains]

The aim of this study was to compare in vitro activity, measuring minimal inhibitory concentration, of amoxicillin or its combination with clavulanic acid against 109 strains of Acinetobacter baumanii, 104 strains of Hemophilus influenzae and 94 strains of Staphylococcus aureus. All these were obtained from different hospitals of the Santiago Metropolitan Region. Amoxicillin-clavulanic acid association did not improve the activity of amoxicillin against Acinetobacter. The association was not active against methicillin resistant strains of S aureus; instead, it significantly increased the activity of amoxicillin against methicillin susceptible strains. All the H influenzae strains were susceptible to the combination.

[Invasive Haemophilus influenzae type B infections in infancy (1981-1990)]

We report the epidemiology of invasive Haemophilus influenzae type B infections. The study is based on 58 children and was carried out during the years from 1981 to 1990. Sixty-three percent of the patients had meningitis, 10.3% had arthritis, 10.3% had epiglottitis, 8.6% had cellulitis and 6.9% had pneumonia. Thirteen percent of the cases were children who were less than 6 months old, 34.4% were less than 12 months old, 70.6% were less than 24 months of age and 93% were less than 4 years old. Among the latter, 90% of the children with epiglottis or pneumonia were 24 months or older compared with 16% of the patients with meningitis, arthritis or cellulitis (p < 0.001). Sixty-three percent of the isolated strains of Haemophilus influenzae type B were resistant to ampicillin and 19.2% of the strains were resistant to ampicillin and chloramphenicol.

Molecular characterization of resistance plasmids in epidemiologically unrelated strains of multiresistant Haemophilus influenzae

Thirty-three epidemiologically unrelated strains of ampicillin-chloramphenicol-resistant isolates of Haemophilus influenzae (22 type b, 11 unencapsulated), isolated over 10 years in Belgium, were compared with 53 ampicillin-resistant chloramphenicol-susceptible isolates (22 type b, 31 unencapsulated). All ampicillin-chloramphenicol-resistant and 76% of ampicillin-resistant chloramphenicol-susceptible strains were resistant to tetracycline, kanamycin, or both. Resistance to these antibiotics was specified by a 37- to 44-MDa conjugative plasmid. The genetic relatedness of these plasmids and of those in multiresistance strains from Spain was investigated. Plasmids specifying ampicillin-chloramphenicol-tetracycline-kanamycin resistance in Belgium or in Spain had highly related restriction fragment patterns. By homoduplex analysis, they had similar molecular organization and contained a structure identical to Tn10-TnCm, a transposon previously identified in chloramphenicol-tetracycline-resistant H. influenzae. Plasmids coding for different resistance phenotypes had less resemblance by restriction endonuclease analysis; however, study of heteroduplex molecules indicated they shared a high proportion of core sequences. These findings support the hypothesis of independent transposition events resulting in resistance plasmids of close molecular organization.

Haemophilus test medium versus Mueller-Hinton broth with lysed horse blood for antimicrobial susceptibility testing of four bacterial species

Studies were undertaken to determine whether broth microdilution susceptibility tests could be standardized by using a single medium for testing fastidious respiratory pathogens. Mueller-Hinton broth with lysed horse blood and the broth version of Haemophilus Test Medium (HTM) were directly compared. Ten orally administered agents were found to give essentially identical results in both media but minor differences were noted. Because the test are easier to read when HTM broth is used, that medium is to be preferred for routine testing of Haemophilus influenzae, Streptococcus pneumoniae, Streptococcus pyogenes and Moraxella catarrhalis isolates by the microdilution procedure.

[Pharmacokinetic, bacteriological and clinical studies on cefditoren pivoxil in children]

Pharmacokinetic, bacteriological and clinical studies on cefditoren pivoxil (CDTR-PI, ME 1207) were performed in children. The results were as follows: 1. A total of 18 patients (19 infections) were treated with CDTR-PI. The doses ranged 2.1-3.2 mg/kg, and it was orally administered 3 times daily, for 4-10 days. Clinical efficacies of CDTR-PI in 18 patients with 19 bacterial infections (3 with tonsillitis, 1 with bronchitis, 7 with pneumonia, 1 with acute maxillary sinusitis, 4 with otitis media, 1 with urinary tract infection, 2 with skin and soft tissue infection) were evaluated as excellent in 13 infections and as good in 6 infections with an efficacy rate of 100%. Twelve causative strains of 5 species were found in 11 patients. Streptococcus pneumoniae in 2 cases out of 3, Haemophilus influenzae in 4/4, Staphylococcus aureus in 2/2, Haemophilus parainfluenzae in 2/2 and Escherichia coli in 1/1 were eradicated. Two patients had mild diarrhea but did not need specific treatment. Severe adverse reaction was not observed in any of the 18 patients. 2. MICs of CDTR were examined against 4 clinically isolated S. pneumoniae strains. Two strains of S. pneumoniae were relatively resistant to penicillins. 3. Pharmacokinetic studies Peak serum CDTR concentrations in 3 patients were 2.38 micrograms/ml, 0.72 micrograms/ml and 2.25 micrograms/ml at a dose of CDTR-PI 3 mg/kg orally administered at 30-minute after meal.(ABSTRACT TRUNCATED AT 250 WORDS)

Haemophilus influenzae infection of human respiratory mucosa in low concentrations of antibiotics

We examined the effects of 0.25 and 0.5 minimal inhibitory concentrations (MIC) of amoxicillin, loracarbef, and ciprofloxacin on the interaction of a clinical isolate of nontypable Haemophilus influenzae (NTHi) with human adenoid organ culture. Adenoid tissue was embedded in agar so that only the mucosal surface was exposed. Minimum essential medium containing NTHi with or without antibiotics was added to the organ culture and incubated with 5% CO2 at 37 degrees C for 24 h. The organ cultures (n = 6) were assessed for several parameters by light microscopy (LM) and transmission electron microscopy (TEM). Bacterial viable counts after 24 h were not significantly different in all organ cultures. Compared with uninfected controls at 24 h, infection with NTHi caused significant (p < 0.05) damage to epithelium as assessed by LM: reduced ciliary beat frequency (CBF), disruption of epithelium integrity, and reduced number of ciliated sites. TEM showed extrusion of cells from the epithelial surface, loss of cilia from ciliated cells, cytoplasmic blebbing, and mitochondrial damage. In the presence of 0.25 and 0.5 MIC of all three antibiotics, the mucosal damage was significantly less (p < 0.05). We conclude that in the presence of sub-MIC levels of amoxicillin, loracarbef, and ciprofloxacin, NTHi infection causes less functional (CBF) and structural damage.

[A clinical study on cefditoren pivoxil granules in the pediatric field]

The clinical efficacy of cefditoren pivoxil (CDTR-PI, ME 1207) was evaluated in 45 patients with various infections. CDTR-PI was administered after meals at a dose of 3 mg/kg t.i.d. to most patients. The clinical efficacy rate was 95.3%. As side effects, diarrhea occurred in 2 patients. Cefditoren showed excellent antibacterial activities against Haemophilus influenzae, Streptococcus pyogenes and Streptococcus pneumoniae, and was more effective against Staphylococcus aureus than other cephems.

In vitro susceptibility test practices with Haemophilus influenzae among College of American Pathologists survey participants in the United States

Questionnaire results from 5233 clinical microbiology laboratories participating in the College of American Pathologists (CAP) survey program in the United States were used to establish current standards of practice with respect to in vitro susceptibility testing of Haemophilus influenzae. The results of this CAP survey indicated that the recently developed National Committee for Clinical Laboratory Standards (NCCLS) guidelines for H. influenzae susceptibility tests have been widely adopted, particularly with regard to the medium used to perform susceptibility tests. Haemophilus test medium (HTM) is now the most commonly used medium and there exists a general level of satisfaction (approximately 80%) with medium performance. Specific methodologic recommendations of the NCCLS, however, are often not being followed, for example, length and atmosphere of incubation and means of preparing inocula. beta-Lactamase assays constitute a very commonly employed means of assessing ampicillin activity. Among susceptibility test methods, disk diffusion (82.2%) is much more commonly used compared with broth microdilution (17.8%) procedures. Data are provided regarding the most commonly tested antimicrobials as well as some of the problems encounted when using current NCCLS methods for susceptibility tests with H. influenzae. Finally, the CAP survey questionnaire revealed that many laboratories have applied HTM to susceptibility tests with other fastidious bacteria such as pathogenic Neisseria sp., streptococci, and Moraxella catarrhalis.

Institution-specific patterns of infection and Gram's stain as guides for empiric treatment of patients hospitalized with typical community-acquired pneumonia

STUDY OBJECTIVE

To determine the appropriateness of cefazolin as empiric treatment of typical, as opposed to atypical, bacterial community-acquired pneumonia at our institution.

DESIGN

Combination of retrospective chart review and prospective determination of microbial susceptibilities and cefazolin-associated cost savings.

SETTING

General acute-care referral hospital.

PATIENTS

We evaluated the charts of patients discharged with a diagnosis of community-acquired pneumonia over a 10-year period. Gram's stains and culture results of sputum samples processed over 2 months were analyzed to determine the ability of the stains to predict positive Haemophilus influenzae cultures. The susceptibility and beta-lactamase status of clinical isolates of H. influenzae were determined. Cost savings of cefazolin as empiric treatment for community-acquired pneumonia were evaluated.

MEASUREMENTS AND MAIN RESULTS

The frequency of H. influenzae pneumonia at our institution was 15% of the three major bacterial community-acquired pneumonias. Gram's stain was highly accurate in predicting the presence or absence of Haemophilus sp in sputum. Five patients had positive outcomes with cefazolin treatment despite being diagnosed with H. influenzae pneumonia. The organism isolates demonstrated intermediate sensitivity to cefazolin and 85% were beta-lactamase negative. Our program that encourages empiric use of cefazolin over cefuroxime for typical bacterial community-acquired pneumonia has allowed a modest projected annual cost savings of $24,000.

CONCLUSIONS

We concluded that when Gram's stain of sputum does not show Haemophilus sp in patients with typical bacterial community-acquired pneumonia, empiric treatment with cefazolin is appropriate and results in cost savings.

Composition of the peptidoglycan of Haemophilus influenzae

The composition of the peptidoglycan of Haemophilus influenzae was determined by analyzing glycopeptides generated by M1 muramidase hydrolysis using high pressure liquid chromatography, fast atom bombardment mass spectrometry, and fast atom bombardment collisionally activated dissociation tandem mass spectrometry, and amino acid analysis. The structures of 17 glycopeptides, representing 96% of the total peptidoglycan, were ascertained. Fifteen glycopeptides resembled species described for Escherichia coli peptidoglycan (Glauner, B., and Schwarz, U. (1983) The Target of Penicillin (Hackenbeck, R., ed), Walter de Gruyter, Berlin pp. 29-34) as compared with 9 in common with Bordetella pertussis (Tuomanen, E., Schwartz, J., Sande, S., Light, K., and Gage, D. (1989) J. Biol. Chem. 264, 11093-11098). Substitutions for L-alanine in the fourth position of the stem peptide included glycine, aspartic acid, and serine. The peptidoglycan was 27% cross-linked, 2% of which formed between diaminopimelic acid residues. No species was identified containing lysyl-arginine residues characteristic of lipoprotein. The peptidoglycan of non-beta-lactamase-mediated antibiotic-resistant H. influenzae differed from that of sensitive strains by an increase in the amount of disaccharide tripeptides and a decrease in 1,6-anhydro dimers. Both changes were transformable properties that changed in a stepwise fashion in parallel with the degree of antibiotic resistance.

[A study on the carrier state of Haemophilus influenzae in pharynx in healthy children in Beijing Area]

One hundred and fifteen healthy children in 2 kindergartens of Beijing City were enrolled in a study for carrier state of Haemophilus influenzae (HI) in pharynx. Nontypable HI flora was found in 32.2% (37/115) in this group. There were no significant differences of carrier state in sex, age, and season in these children. Antibiotic sensitivity test showed that some HI strains isolated were resistant to ampicillin and tetracycline (5/34 vs 4/34), most strains resistant to SMZ Co (21/34).

A comparative study of cephradine, amoxycillin and phenoxymethylpenicillin in the treatment of acute dentoalveolar infection

A comparative double blind trial was undertaken of the efficacy of cephradine, amoxycillin and phenoxymethylpenicillin in the treatment of acute dentoalveolar abscesses. Patients were admitted to the trial with acute dentoalveolar abscesses with systemic involvement and assessments were made of pain, swelling, temperature and lymphadenopathy. After admission to the trial appropriate surgical therapy was undertaken. The patients were then given either phenoxymethylpenicillin 250 mg four times daily, cephradine 500 mg twice daily or amoxycillin 250 mg three times daily, all for 5 days. The patients were assessed after 2 days and 5 days. All the patients recovered with those taking cephradine showing the best recovery in the first two days of treatment.

Bacterial pneumonia. S pneumoniae and H influenzae are the villains

Bacterial pneumonia isn't what it used to be. The most common causes, Streptococcus pneumoniae and Haemophilus influenzae, are developing strains that are resistant to powerful antibiotics: How do you choose a therapeutic agent? New organisms are being discovered to be culprits in this disease: How do you keep track of them? New drugs are being developed every day: How does that help if initial treatment is almost always empirical? Dr Wisinger identifies the problems and offers advice.

Preincubation of Haemophilus influenzae with subinhibitory concentrations of macrolides: influence on human neutrophil chemiluminescence

Preincubation of Haemophilus influenzae with antibiotics may influence opsonophagocytosis as studied by chemiluminescence. Two strains of H. influenzae (strain 1 [type b] and strain 2 [uncapsulated]) were pretreated with erythromycin, roxithromycin, clarithromycin, and azithromycin for 1 h in Haemophilus test medium (the last 25 min was either without serum or with 10% fresh serum or 10% decomplemented serum). Human neutrophils were stimulated with a pretreated or control inoculum at four different bacterium/neutrophil ratios and tested for luminol chemiluminescence with an LKB luminometer. The results were normalized for bacterium/neutrophil ratio and compared by the two-sided Wilcoxon test. Pretreatment of bacteria with one-half of the MICs of erythromycin, clarithromycin, and roxithromycin produced nonsignificant (P > 0.05) increases in the chemiluminescence response (means of 23% for strain 1 and 4% for strain 2). Pretreatment with azithromycin at one-half of the MIC produced an increase in the chemiluminescence response induced by serum-opsonized strain 1 (320% +/- 36% [mean +/- standard error of the mean]) and strain 2 (107% +/- 20%) (P < 0.05). This increase was concentration dependent: for strain 1, 60% +/- 18% at one-fourth of the MIC to 440% +/- 41% at the MIC; for strain 2, 10% +/- 5% at one-fourth of the MIC to 300% +/- 20% at the MIC. For strain 1, the maximal increase with azithromycin pretreatment (at the MIC) required opsonization with fresh serum. Opsonization with decomplemented serum was associated with a 53% +/- 21% increase; this increase was 28% +/- 3% in the absence of serum. For strain 2, azithromycin reduced the lag phase of the chemiluminescence response induced by the absence of serum but did not alter the chemiluminescence response in the presence of decomplemented serum. A significant contribution of soluble factors in the enhanced response observed with bacteria preincubated with azithromycin was excluded. The increase of the chemiluminescence response with azithromycin pretreatment was probably due to improvement in complement-dependent opsonization for strain 1 and to improvement in both serum-independent and serum-dependent opsonization for strain 2.

Evaluation of amoxicillin clavulanate twice daily versus thrice daily in the treatment of otitis media in children. Danish-Swedish Study Group

A total of 311 children who had recurrent otitis media or who had experienced failure of initial treatment of acute otitis media with phenoxymethylpenicillin, amoxicillin, ampicillin esters or cefaclor were entered into a single-blind study in two parallel groups in order to compare the clinical efficacy and safety of amoxicillin/clavulanate suspension given b.i.d. or t.i.d. for seven days. The patients were examined prior to the start of treatment, at an early follow-up visit 9 to 12 days after the start of treatment and at a late follow-up visit about three weeks later. Specimens for bacteriological culture were taken from the nasopharynx at entry, at the early follow-up visit, and at the late follow-up visit if there were symptoms of otitis. Both treatment groups showed a similar response, 90% or more of the patients being cured or showing improvement at the time of the early follow-up visit. The initial nasopharyngeal cultures showed growth of Haemophilus influenzae in 53% of the patients, Moraxella catarrhalis in 43% and Streptococcus pneumoniae in 39%. After treatment, cultures showed elimination of the initial pathogens in 30% of patients in both groups and recolonization in 23% in both groups. Haemophilus influenzae was the bacteria most frequently found in the nasopharynx at the first follow-up visit. Adverse effects, which consisted mostly of gastrointestinal and dermatological reactions, tended to be more common in the b.i.d. group but the difference was not statistically significant.

The in-vitro activity of OPC-17116, a new 5-methyl substituted quinolone

The in-vitro activity of the new 5-methylated fluoroquinolone OPC-17116 was compared with that of other fluoroquinolines and beta-lactams against a total of 690 bacterial strains. With the exception of Klebsiella and Serratia spp., 90% of the Enterobacteriaceae were inhibited by 0.25 mg/L. OPC-17116 inhibited 90% of Serratia spp. at 8 mg/L and Klebsiella spp. at 4 mg/L. Moraxella catarrhalis and Haemophilus influenzae were highly susceptible (MIC90 < or = 0.03 mg/L). Pseudomonas aeruginosa were more susceptible to ciprofloxacin (MIC90 0.25 mg/L) than OPC-17116 (MIC90 1 mg/L). Generally, OPC-17116 was more active than ciprofloxacin against Gram-positive cocci, 90% of Staphylococcus spp. being inhibited by < or = 0.25 mg/L. OPC-17116 displayed greater activity than ciprofloxacin against Chlamydia spp. (MICs < or = 0.12 and < or = 2 mg/L, respectively).

Ecology of Haemophilus influenzae and Haemophilus parainfluenzae in sputum and saliva and effects of antibiotics on their distribution in patients with lower respiratory tract infections

Nine patients with lower respiratory tract infections were used to study in detail the effect of ampicillin or erythromycin on the colonization patterns of Haemophilus influenzae and Haemophilus parainfluenzae in sputum and saliva. H. influenzae was isolated from purulent sputum of eight patients before the start of treatment. Ampicillin was more effective than erythromycin at clearing H. influenzae from sputum and in decreasing purulence. By careful characterization of multiple strains, the changes in biotype distribution and antibiotic susceptibility patterns were shown. Five biotypes of H. influenzae were associated with chest infection, with type II predominating. Mixed biotype infections occurred in five patients. Most saliva contained multiple biotypes of H. parainfluenzae. Neither antibiotic selected resistant haemophili in saliva or sputum. After treatment with ampicillin, the mucoid sputum was colonized with ampicillin-susceptible H. parainfluenzae biotypes previously found in saliva. We postulate that as inflammation decreases at the bronchial mucosa, the ampicillin concentration drops, allowing ampicillin-susceptible oral H. parainfluenzae isolates to seed the residual mucoid sputum.