The intrabronchial microbial flora in chronic bronchitis patients: a target for N-acetylcysteine therapy?

Chronic bronchitis is common among smokers, often together with recurrent infectious exacerbations. Streptococcus pneumoniae and Haemophilus influenzae are the pathogens traditionally considered most important. N-acetylcysteine (NAC) treatment has been shown to reduce the number of infectious exacerbations in patients with chronic bronchitis. The mechanism behind this is unknown. We attempted to characterize the intrabronchial bacterial flora in patients with chronic bronchitis in an infection-free interval, and to determine whether pharmacological and immunological factors effected the bacterial occurrence. Twenty two smokers with non-obstructive chronic bronchitis, 19 smokers with chronic bronchitis and chronic obstructive pulmonary disease (COPD) and 14 healthy nonsmokers underwent bronchoscopy. To obtain uncontaminated intrabronchial samples, a protected specimen brush was used. Quantitative bacterial cultures and virus isolations were performed. Significantly positive bacterial cultures (> 1,000 colony-forming units (cfu).ml-1) were found only in the patients. S. pneumoniae and H. influenzae were found in five patients, and only in the patients without NAC treatment. The most common bacterium was alpha-haemolytic streptococcus. Negative cultures were more common in the healthy controls. Of the various factors examined, only NAC medication had an influence on bacterial numbers. Significantly fewer patients with NAC medication had positive cultures (3 out of 16) than in the group of patients without NAC therapy (15 out of 21). Our results confirm that chronic bronchitis in smokers leads to increased intrabronchial bacterial colonization. We could also confirm that 1,000 cfu.ml-1 is an adequate cut-off level for significant bacterial growth when using the protected specimen brush. NAC medication was associated with low bacterial numbers.

[The biological properties of Haemophilus influenza isolated from healthy children and from patients with acute and chronic respiratory diseases]

The comparative study of the biological properties of H. influenzae strains isolated from healthy children and from patients with acute and chronic respiratory diseases has been made, taking into account the biochemical features (biotypes) and adhesive activity of these strains. Differences in various biotypes of H. influenzae strains isolated from patients with bronchopulmonary diseases and from healthy carriers have been established. H. influenzae strains isolated from various sources differ by their adhesive properties: strains isolated from patients with acute bronchopulmonary diseases have the highest adhesive activity, while strains isolated from healthy controls have the lowest adhesive activity. The data thus obtained indicate the possible dependence of the degree and duration of the colonization of the respiratory tract by H. influenzae on the biological properties of these microorganisms. The monitoring of the sensitivity of H. influenzae strains to antibiotics has demonstrated that these strains retain high sensitivity to ampicillin, chloramphenicol, gentamicin and exhibit a tendency towards an increase in resistance to penicillin and erythromycin.

[Bacteremia caused by Haemophilus influenzae with special reference to its relation to HIV infection]

BACKGROUND

The association between infection by Haemophilus influenzae and infection by the human immunodeficiency virus (HIV) has been clearly demonstrated. However, some characteristics of this association still remain poorly defined.

METHODS

The medical records of all adult patients admitted to a general hospital over a period of four years with blood cultures positive for Haemophilus influenzae were reviewed. Patients were grouped according to whether HIV infection or no evidence of HIV infection existed. Clinical and epidemiologic data were collected and compared. The main features of data corresponding to seropositive patients are reported.

RESULTS

Of a total of 29 cases of bacteremia by Haemophilus influenzae, 19 were diagnosed in adults: 5 in patients with HIV infection and 14 in patients without HIV infection. Over the following 18 months one additional case was reported. The incidence (calculated in cases per 100,000 people/year) was 1.9 in the general population, 1.5 in adults, 70 in adults with HIV infection and 360 in AIDS patients. All the cases diagnosed in adults below the age of 30 years were reported in HIV carriers. Five of the 16 (31%) H. influenzae strains tested were resistant to ampicillin, with a significant difference being found between those isolated from HIV positive patients (4/5) and from HIV negative patients (1/11). No patient with HIV infection died during the episode. But five of the HIV negative adults died.

CONCLUSIONS

HIV infection seems to be frequent risk factor for bacteremia by Haemophilus influenzae. It should always be considered on diagnosis in adults under the age of 30. Likewise, the high probability of resistance to ampicillin should also be taken into account for the empiric treatment.

[In vitro antimicrobial susceptibilities and beta-lactamase production of clinical isolates. beta-Lactamase Study Group in Chubu-area]

Antimicrobial susceptibilities and beta-lactamase production of clinical isolates from 1986 to 1991 except 1988 were determined. beta-Lactamase was detected frequently in Escherichia coli (84.7%), Klebsiella pneumoniae (65.4%), Staphylococcus aureus (62.3%), and not frequently in Haemophilus influenzae (22.4%). Methicillin-resistant S. aureus was also resistant to many antimicrobials except to arbekacin and minocycline, and imipenem showed markedly high activity against methicillin-sensitive S. aureus. Susceptibilities of E. coli and K. pneumoniae to cefuzonam, imipenem and ofloxacin were quite high and that of H. influenzae to ofloxacin and cefuzonam was also very high.

In vitro susceptibility of recently isolated respiratory tract pathogens to minocycline and comparable antibiotics. A multicentre study

The in vitro susceptibility of recently isolated respiratory tract pathogens (217 S. pneumoniae, 202 H. influenzae and 178 M. catarrhalis, has been examined against minocycline, doxycycline, amoxycillin, amoxyclavulanate, cefuroxime, clarithromycin and ciprofloxacin. M. catarrhalis was fully susceptible to all antibiotics except amoxycillin (62% susceptible). H. influenzae showed full susceptibility to minocycline, cefuroxime and ciprofloxacin but different percentages of resistance to the other antibiotics. Among S. pneumoniae isolates resistance was observed to all antibiotics tested between 12% to beta-lactams and 22% to doxycycline.

Susceptibility of clinically significant Haemophilus influenzae strains to oral antimicrobial agents used in Saudi Arabia

The incidence of beta-lactamase production by Haemophilus influenzae strains and their susceptibility to commonly used oral antimicrobial agents were evaluated. From 1990 to 1992, 600 significant isolates of H. influenzae obtained from various hospitals throughout Saudi Arabia were identified, serotyped and tested for beta-lactamase production using cefinase discs and susceptibility to various antibiotics using the agar dilution method. The study revealed that 17% of the strains produced beta-lactamase; 21% of them were type b. The overall level of resistance was 30% to erythromycin, 28% to tetracycline, 14.3% to co-trimoxazole, 6.6% to chloramphenicol, 1.8% to amoxicillin-clavulanate and 1.5% to cefaclor. About 1.3% of the strains that did not produce beta-lactamase were resistant to ampicillin. Resistance of H. influenzae to antibiotics is increasing and in several parts of the world resistance to ampicillin has reached substantial levels particularly in type b strains. Information on resistance is needed for the appropriate selection of initial empiric therapy among patients in whom H. influenzae is a suspected pathogen.

In vivo therapeutic efficacy of cefdinir (FK482), a new oral cephalosporin, against Staphylococcus aureus and Haemophilus influenzae in mouse infection models

Cefdinir (FK482), a new oral cephalosporin, displayed potent oral activity versus induced infections in mice. In studies using beta-lactamase-nonproducing (beta LAC-) and -producing (beta LAC+) Staphylococcus aureus strains, respective PD50s (in mg/kg) were 11 and 24 for preventing subcutaneous abscess and 2.7 and 2.3 for preventing lethal systemic infection. In studies using beta LAC- and beta LAC+ Haemophilus influenzae, respective PD50s were 5.8 and 3.1 for preventing lethal systemic infection. Time-kill studies versus H. influenzae showed that 6- to 12-mg/kg dosing was effective in reducing viable counts of these strains in blood by > or = 100-fold by 24 h after challenge. This in vivo performance was comparable to or exceeded values generated by cefaclor, cefpodoxime proxetil, and ampicillin.

Effect of pre-operative antibiotic treatment on the bacterial content of the tonsil

The impact of 7 days pre-tonsillectomy antibiotics on the aerobic bacterial content of the tonsil was studied in 70 consecutive patients. One group received no antibiotic, one group received pre-operative amoxycillin and the final group, pre-operative cefaclor. The qualitative bacteriology was similar in the three groups Haemophilus influenzae was the predominant isolate present in the centre ('core') of the resected tonsil. Similar numbers of beta-lactamase producers including H. influenzae and Straphylococcus aureus were found in all three groups. Quantitative bacteriology of the tonsil core demonstrated that there was a significant reduction in core tonsil pathogens associated with antibiotic therapy. The most statistically significant difference was between the untreated control group and the cefaclor treated group. We conclude that in patients with established recurrent acute tonsillitis, oral antibiotics penetrate the diseased tonsil and influence the predominant core aerobic microflora.

[Multiple antibiotic resistance in Haemophilus influenzae related to serogroup B]

AIM

To study the association between multiply antibiotic resistance in Haemophilus influenzae and H. influenzae type B, and to describe levels and patterns of antibiotic resistance.

METHODS

Statistical analysis and susceptibility of 231 H. influenzae strains (52 type B and 179 non-typable ) isolated consecutively from pediatric patients.

RESULTS

Resistance levels for type B and non-typable strains were: Ampicillin, 55.3% vs 28.8%; Chloramphenicol, 44.7% vs 9.2%; Ampicillin plus chloramphenicol, 40.4% vs 7.6%; cotrimoxazole, 89.3% vs 67.4%; resistance to six or more antibiotics, 36.0% vs 3.8%.

CONCLUSION

Multiply antibiotic resistance in H. influenzae is strongly associated with type B strains, with age of 4 or younger, and with isolation from CSF or blood. Resistance is sustained over long periods of time.

The pharmacokinetics, tissue penetration and in-vitro activity of loracarbef, a beta-lactam antibiotic of the carbacephem class

The pharmacokinetics of loracarbef in plasma and a mild inflammatory exudate were studied in human volunteers. After a single oral dose of 400 mg, a mean maximum drug concentration (Cmax) of 17.8 mg/L was achieved in the plasma at 1.2 h (mean Tmax). The mean plasma elimination half-life (T1/2) was 1.3 h. In the inflammatory exudate the mean Cmax was 8.9 mg/L at a mean Tmax of 2.0 h and with a mean T1/2 of 1.7 h. The mean penetration into the inflammatory exudate was 90.1%. The in-vitro activity of loracarbef was determined against Haemophilus influenzae and Moraxella catarrhalis (MIC90s of 4 mg/L and 1 mg/L respectively, regardless of beta-lactamase production), as well as Streptococcus pneumoniae (MIC90 of 2 mg/L). Loracarbef was also active against Escherichia coli, Proteus mirabilis and Klebsiella pneumoniae (MIC90s of < or = 2 mg/L). The in-vitro activity and pharmacokinetics of loracarbef suggest that it would be efficative therapy for patients with community-acquired respiratory and urinary tract infections caused by the most frequently-encountered bacterial pathogens.

Erythromycin, clarithromycin, and azithromycin: use of frequency distribution curves, scattergrams, and regression analyses to compare in vitro activities and describe cross-resistance

MICs of erythromycin, clarithromycin, and azithromycin for 852 recent clinical isolates were determined by broth microdilution methods. Frequency distribution curves, scattergrams, and regression analyses were used to compare in vitro activities and describe cross-resistance. Clarithromycin was the most active drug against Bacteroides spp. but the least active against Haemophilus influenzae. Azithromycin was most active against H. influenzae, Moraxella catarrhalis, Pasteurella multocida, and Fusobacterium spp. but the least active against Streptococcus spp. and Enterococcus spp. All three drugs had equivalent activities against Staphylococcus spp. and gram-positive anaerobes. None of the three drugs was particularly active against members of the family Enterobacteriaceae or nonfermentative gram-negative bacilli, although concentrations of 4 micrograms of azithromycin per ml inhibited some strains of the family Enterobacteriaceae (particularly Escherichia coli and Citrobacter diversus) and Acinetobacter baumannii. Although relative drug activities varied by organism, organisms relatively susceptible to one were relatively susceptible to all and organisms relatively resistant to one were relatively resistant to all; an exception was fusobacteria, which were usually susceptible only to azithromycin. Cross-susceptibility and cross-resistance were, therefore, the rule (except for Fusobacterium spp.), although the percentage of susceptible organisms could be varied considerably on the basis of the selection of breakpoints.

Use of nasopharyngeal isolates of Streptococcus pneumoniae and Haemophilus influenzae from children in Pakistan for surveillance for antimicrobial resistance

Antimicrobial resistance of Streptococcus pneumoniae and Haemophilus influenzae presents a challenge to clinical case management, particularly in programs for acute respiratory tract infection (ARI), including pneumonia, in developing countries. To determine whether nasopharyngeal isolates of S. pneumoniae and H. influenzae from a clinically defined group of children could be used to predict the prevalence of antimicrobial resistance of strains that cause disease, 601 urban children with ARI, 133 healthy urban children and 285 rural children were evaluated in Pakistan. Of the urban children with ARI, 216 (35.9%) were bacteremic, predominantly with S. pneumoniae (108 children) and H. influenzae (100 children). Overall 631 (61.9%) children carried S. pneumoniae and 381 (37.4%) carried H. influenzae. The proportions of nasopharyngeal isolates of both organisms from urban children with ARI resistant to penicillin or ampicillin, trimethoprim/sulfamethoxazole, chloramphenicol and erythromycin were similar to the proportions of resistant blood isolates. Nasopharyngeal isolates from rural children had lower rates of resistance to some antimicrobial agents. These findings suggest that nasopharyngeal isolates of S. pneumoniae and H. influenzae from children with ARI can be used to conduct surveillance for antimicrobial resistance in a defined geographic area. Such surveillance would aid programs in developing countries in making a rational choice of antimicrobial agents for use in clinical management of bacterial diseases, including pneumonia.

Prevalence of potential respiratory disease bacteria in children in Ethiopia. Antimicrobial susceptibility of the pathogens and use of antibiotics among the children

Acute respiratory infections are primary causes of morbidity and mortality in children in developing countries. This project was designed to investigate antimicrobial susceptibility of respiratory tract pathogens isolated from children in rural and city areas, and to contribute to the rational choice of antibiotics for respiratory tract infections in children in Ethiopia. Nasopharynx and throat cultures were taken from all children under five years of age in three study areas representing different levels of contact with health care and accessibility to modern drugs, such as antibiotics. In all, 1126 children were cultured. Haemophilus influenzae and Streptococcus pneumoniae were both found in 85-90% of the children, and beta-haemolytic streptococci group A in 12%. The level of antimicrobial resistance was low. None of the 954 strains of H. influenzae were beta-lactamase producers. Pneumococci were susceptible to penicillin. The use of antibiotics was also low; 11 of 1126 children had antibiotics on the day of culture or the day before. The choice of antibiotics was not limited by resistance, and emphasis could be put on low cost, minimizing adverse drug reactions and ecological impact.

[Antimicrobial activity of cefodizime against fresh clinical isolates]

In order evaluate antimicrobial activities of cefodizime (CDZM), minimum inhibitory concentrations (MIC's) of CDZM and other control drugs were determined against various clinical isolates, that were sent to our center from nation-wide medical institutions or were isolated and identified in our laboratory from various specimens of infected patients. The followings are a summary of the results: 1. Bacterial species with no or few strains resistant to cephems including CDZM included Streptococcus pyogenes, Haemophilus influenzae, Citrobacter diversus, most of Klebsiella pneumoniae and Proteus mirabilis. Some strains of Klebsiella oxytoca were resistant to cephems increases in beta-lactams resistant Streptococcus pneumoniae and cephem resistant Escherichia coli seemed likely. Among Citrobacter freundii, Enterobacter spp., Serratia marcescens, Proteus vulgaris, Morganella morganii and Providencia spp. belonging to a category of so-called "mildly toxic bacteria", high portions of the strains examined were resistant to cephems including CDZM and these strains were also resistant to new quinolones, thus they showed multiple drug resistance. 2. MIC90's of CDZM against Streptococcus spp., H. infleunzae, Moraxella subgenus Branhamella catarrhalis, E. coli, Klebsiella spp. and P. mirabilis, frequently found in daily treatment of infections, were less than < or = 0.025 to 1.56 micrograms/ml. This indicates that CDZM would be expected to have enough antibiotic activity in infections caused by above mentioned bacteria. However, cautions are needed in the treatment of infections by beta-lactam resistant S. pneumoniae, cephem resistant E. coli and cephem resistant K. oxytoca with CDZM. 3. Among the above mentioned "mildly toxic bacteria", many multiple drug resistant strains exist. Therefore, we evaluated an usefulness of concomitant use of CDZM with aminoglycosides in the treatment of infections by these bacteria, using other reports which indicates the usefulness in vitro and in vivo. 4. Antibacterial activities of CDZM we observed in this study seem to indicate that CDZM concentrations in infected areas are maintained at above MIC levels for relatively long periods of time.

[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.