Normal Respiratory Flora Research Articles

Prognostic implications of initial oropharyngeal bacterial flora in patients with cystic fibrosis diagnosed before the age of two years

To evaluate the significance of early bacteriologic findings in infants and younger children with cystic fibrosis, we divided patients identified at < or = 2 years of age into groups by initial oropharyngeal culture: group NF, normal respiratory flora (n = 17); group SA, Staphylococcus aureus without Pseudomonas aeruginosa (n = 20); group PA, P. aeruginosa without S. aureus (n = 6); group PA/SA, P. aeruginosa and S. aureus (n = 7); and group O, other potentially pathogenic bacteria (n = 31). Follow-up of patients ranged in age from 5.4 to 13 years. At diagnosis, group PA/SA had lower Brasfield scores (p < 0.02) and higher gamma-globulin levels (p < 0.03) than the other groups. Five years after diagnosis, Brasfield scores were significantly lower in groups PA and PA/SA compared with the other groups; mean gamma-globulin levels did not differ significantly among the groups. Groups PA and PA/SA also had evidence of significantly greater obstructive pulmonary disease by spirometry than groups NF and O. Group PA/SA had a 10-year survival estimate of 57%, significantly lower than the 92% to 100% estimates of the other four groups (p < 0.0001). Thus P. aeruginosa in initial oropharyngeal cultures from patients < or = 2 years of age with cystic fibrosis was associated with significantly increased morbidity, and the finding of P. aeruginosa and S. aureus together in initial oropharyngeal cultures with a significantly increased mortality rate during the first 10 years after diagnosis.

Microbiology of acute and chronic sinusitis in children

To determine the bacteriologic cause of acute sinusitis, a sample of sinus secretions must be obtained from one of the paranasal sinuses without contamination by normal respiratory or oral flora that colonize mucosal surfaces. When maxillary sinus aspiration is performed on children who have signs and symptoms of acute sinusitis, bacteria are recovered in high density from 70%. In patients with acute, subacute, or chronic sinusitis who are generally well except for persistent respiratory symptoms, of nasal discharge or cough or both, the usual bacterial isolates are Streptococcus pneumoniae, Haemophilus influenzae, an Moraxella catarrhalis. In contrast, anaerobic organisms and staphylococci should be suspected in patients who have very long-standing symptoms or in those whose symptoms are so severe or complicated that sinus surgery is undertaken.

Identification of type 4 pili in Kingella denitrificans.

Kingella denitrificans is an occasionally pathogenic member of the family Neisseriaceae and is a member of the normal respiratory flora. Electron microscopy, colony morphology types, DNA transformation patterns, and immunoblots suggest that K. denitrificans and K. kingae have type 4 pili. This was confirmed by N-terminal amino acid sequencing for K. denitrificans.

Study on the bacteriological examination of sputum and bronchoscopy specimens from 31 cases with pneumonia due to Chlamydia psittaci

We carried out the bacteriological examination of sputum and bronchoscopy specimens from 31 cases with pneumonia due to C. psittaci. The results obtained were as follows: 1. The positive culture of sputum and bronchoscopy specimens were 38.7% (12/31). 2. The organisms detected from them were 13 strains of gram-negative bacilli, 2 of gram-positive cocci and one gram-positive bacillus. 3. Significant differences were observed in the white blood cell count between the cases of positive culture and those of normal upper respiratory tract flora (p less than 0.05). From the results we conclude that it would be better that we add the proper antimicrobial drugs to chlamydial antibiotics in the treatment of patients with leukocytosis.

An improved screening technique for isolation of Nocardia species from sputum specimens

Three selective isolation media and the paraffin baiting technique were compared with conventional culture (Sabouraud dextrose agar without antibiotic supplement) for the ability to grow and detect nocardiae from simulated sputum specimens. Modified Thayer-Martin medium, incorporating vancomycin, colistin, nystatin and trimethoprim as selective agents, produced the highest recovery rate and with the greatest suppression of normal respiratory tract flora. A clinical evaluation using a screening programme devised for a busy diagnostic microbiology laboratory was performed on 1600 sputum specimens. Inoculating sputum on modified Thayer-Martin medium and extending the initial incubation period of 3 days at 35 degrees C under 10% carbon dioxide to a further 3 weeks at room temperature in a candle jar, led to the diagnoses, which otherwise would have been missed, of pulmonary nocardiosis in 3 patients and pulmonary infections due to Neisseria meningitidis, Pseudomonas cepacia, and Serratia marcescens in a further 22 patients.

FulminantBranhamella catarrhalistracheitis

Branhamella catarrhalis, a well known commensal of the normal respiratory flora, is being increasingly implicated as an aetiological agent in various acute respiratory and non-respiratory infections. B. catarrhalis has demonstrated a particular predilection for turning pathogenic in the immunocompromised host. Bacterial tracheitis, presenting as an acute airway obstruction, is commonly caused by Staphylococcus aureus and Haemophilus influenzae. The unusual occurrence of a fulminant B. catarrhalis bacterial tracheitis in a previously normal and healthy Indian child is the subject of this communication.

Bacteriology of tonsil surface and core in children.

The tonsils of 97 children undergoing tonsillectomy were studied to determine the correlation between surface culture swab and culture of tonsillar core. In many cases, pathogenic organisms were found in the tonsil core, despite the fact that surface cultures revealed only normal respiratory flora. The tonsil core cultures showed a high incidence of Hemophilus influenzae and Staphylococcus aureus, which was rarely reflected on surface culture. The study indicates that pharyngeal swab cultures do not reliably reflect the presence of pathogens in the tonsil core. The value of parameters such as history of recurrent bouts of tonsillitis and presence of erythema or cryptic debris on physical examination for predicting the differential bacteriology of the tonsil is studied. The implications for treatment of children with adenotonsillar hypertrophy are discussed.

Bacteriologic diagnosis of nosocomial pneumonia following prolonged mechanical ventilation.

Cultures of tracheal secretions, bronchoalveolar lavage (BAL), protected specimen brushes (PSB), and direct lung aspirates were compared with cultures of lung homogenates and histologic findings in 35 baboons after 7 to 10 days of intubation and mechanical ventilation. Six animals received no antibiotics, while the remainder were treated with a variety of prophylactic regimens of intravenous and topical agents. Bacterial contamination at each culture site was expressed as a "bacterial index" (BI), obtained as the sum of the logarithmic concentrations of individual species. In the absence of antibiotics, pneumonias occurred in all animals and were polymicrobial; 56% of organisms in lung tissue were members of the normal upper respiratory tract flora, while 44% were gram-negative bacilli with a mean total bacterial index of 13.94/g. Lobar tissue BI values greater than 6.0/g were found in 77% of lobes containing pneumonias judged by histologic criteria to be moderate or severe in extent, whereas only 7% of lobes with lesser inflammatory changes had similar BI values. The BI values of BAL were linearly related to tissue values, whether the BAL was performed of the same lobe cultured or a different lobe. BAL recovered 74% of all species present in lung tissue compared to 41% by PSB and 56% for needle aspirates. False positive specimens were found with similar frequency with these 3 procedures. Tracheal aspirates revealed 78% of organisms found in lung tissue, but 14 of 35 (40%) of species isolated were not present in lung tissue. BAL provides the best reflection of the lung's bacterial burden, both quantitatively and qualitatively, in the setting of prolonged intubation and ventilation.

Detection of Group A Streptococcus

Eight hundred thirty-seven consecutive throat cultures from pediatric patients were cultured comparatively on conventional sheep blood agar and selective agar containing 1.25 micrograms/ml trimethoprim and 23.75 micrograms/ml sulfamethoxazole. In two sequential studies the sheep blood agar-sulfamethoxazole-trimethoprim plates were significantly (P less than 0.01) more sensitive for Group A Streptococcus (Strep-A) detection than conventional sheep blood agar plates or Todd-Hewitt broth using the fluorescent antibody-antigen detection technique. The selective plates inhibited normal upper respiratory flora but not Strep-A. An incubation time of 18 hours was significantly better than one of 4 hours for the detection of Strep-A antigen in cultures incubated in Todd-Hewitt broth alone or Todd-Hewitt-sulfamethoxazole-trimethoprim broth, resulting in a 24% increase in positives. These studies demonstrate that Strep-A detection in throat swab specimens, by either culture or antigen detection, will be influenced by the use of selective antibiotics and incubation time.

Clinical interpretation of beta-lactamase-producing strains of Branhamella catarrhalis in sputum Gram's stain and culture.

Branhamella catarrhalis has been implicated previously as a cause of bronchopulmonary infections. Sputum Gram's stain and culture results suggesting significant infection with beta-lactamase-producing strains of B. catarrhalis were correlated with a retrospective chart review of eight pediatric and ten adult patients. Preexisting pulmonary disease was observed in 12 patients; 5 had a history of aspiration; and 13 were intubated. Clinically, ten patients had pneumonia, five had bronchitis, and three manifested no disease. Only three sputum specimens grew a pure culture of B. catarrhalis, and six specimens yielded B. catarrhalis in the presence of normal upper respiratory flora. Analysis of broth microdilution susceptibility test results showed that 90% of the strains were inhibited at the following minimum inhibitory concentrations (MICs90): ampicillin, 8 micrograms/mL; cefotaxime, 0.5 microgram/mL; cefoxitin, 0.5 microgram/mL; cephalexin, 4 micrograms/mL; cephalothin, 8 micrograms/mL; chloramphenicol, 1 microgram/mL; clindamycin, 4 micrograms/mL; erythromycin, 0.25 microgram/mL; methicillin, 16 micrograms/mL; mezlocillin, 16 micrograms/mL; moxalactam less than or equal to 0.6 microgram/mL; penicillin, 16 micrograms/mL; piperacillin, 8 micrograms/mL; tetracycline, less than or equal to 0.3 microgram/mL; and trimethoprim/sulfamethoxazole, 1.6/30 micrograms/mL. Therapy may have been adequate in only eight (44%) of the cases. However, all but four of the patients, who died of unrelated causes, exhibited resolution of disease. The data indicate that Gram's stain and culture results of sputum specimens suggesting B. catarrhalis bronchopulmonary infection should be interpreted with caution by clinicians.

Community-acquired Pneumonia Caused by Mixed Aerobic Bacteria

Mixed bacterial pneumonia caused by organisms other than anaerobes has been infrequently reported. We describe six cases and review the literature. Two patients had co-infection with S pneumoniae and L pneumophila. Two were infected with S pneumoniae and K pneumoniae and the others simultaneously harbored M tuberculosis and N asteroides. The first two sets of patients had bacteria isolated from usually sterile sites (blood and lung), while the latter harbored repeatedly isolated organisms not usually felt to be part of the normal respiratory flora. Mixed infection may help explain the substantial mortality still seen from pneumonia. This is especially true if Legionella, mycobacteria, or Nocardia species are encountered where routine smears and cultures may not aid in the diagnosis. Poor clinical response to specific antibacterial therapy in pneumonia should trigger further investigation for other potential pathogens.

Improved recovery of group A beta-hemolytic streptococci with a new selective medium.

A new selective group A streptococcus agar (ssA) (BBL Microbiology Systems, Cockeysville, Md.) was evaluated for the recovery and direct plate identification of group A beta-hemolytic streptococci (GABHS) in comparison with sheep blood agar (SBA). A total of 265 GABHS were recovered from 1,116 throat swab specimens on both media, with detection rates of 98.9 and 91.7% for ssA and SBA, respectively. Primary bacitracin disk susceptibility tests were performed on 549 specimens, and presumptive identifications were possible for 81.4% of the GABHS on ssA, as compared with 44.2% on SBA. All of the 120 GABHS recovered from another 567 specimens were identified by a coagglutination method after overnight incubation on ssA, whereas only 70.2% were identified at this interval on SBA. The major advantage of the ssA was the inhibition of normal respiratory flora, permitting improved recovery and rapid identification of GABHS.

Acute Suppurative Parotitis Caused by Anaerobic Bacteria: Report of Two Cases

Staphylococcus aureus is the predominant pathogen in acute suppurative parotitis. Although anaerobic bacteria are prevalent in the normal oral and upper respiratory tract flora and frequently are involved in oral and facial infections, they have seldom been isolated from patients with suppurative parotitis. It may be that a role for anaerobes in parotitis has not been documented because of inadequate specimen transport or anaerobic culture techniques. We describe two cases of acute suppurative parotitis in which cultures yielded anaerobic bacteria. In one case, no aerobes were isolated; in the other, the anaerobe was the predominant organism numerically.