Ear Pathogens Research Articles

Streptococcus pneumoniae resistant to penicillin: incidence and potential therapeutic options.

Streptococcus pneumoniae was recovered from 12 (50%) samples of middle ear fluid of 24 consecutive patients with AOME and in mixed culture of middle ear pathogens from one (4%) additional specimen. Two (15.3%) isolates had intermediate resistance to penicillin (minimal inhibitory concentration (MIC) 0.125 and 1.0 micrograms/mL). The antimicrobial susceptibility to various antimicrobials of 30 S pneumoniae strains recovered from patients seen in the last 12 months was also determined. One of the patients with AOME developed bacteremia that resolved uneventfully, whereas the other developed meningitis. MIC90 was determined from penicillin (2 micrograms/mL), erythromycin (> 32 micrograms/mL), cefaclor (32 micrograms/mL), loracarbef (> or = 64 micrograms/mL), cefixime (16 micrograms/mL), ceftibuten (> 64 micrograms/mL), chloramphenicol (16 micrograms/mL), cefpodoxime (4 micrograms/mL), ciprofloxacin (2 micrograms/mL), cephalexin (> or = micrograms/mL), augmentin (2 micrograms/mL), cefprozil (8 micrograms/mL), clindamycin (64 micrograms/mL), TMP-SXT (> 64 micrograms/mL), clarithromycin (32 micrograms/mL), rifampin (0.06 micrograms/mL), cefuroxime (2 micrograms/mL), cefotaxime (0.25 micrograms/mL), vancomycin (0.25 micrograms/mL), and imipenem (0.5 micrograms/mL). Cefprozil, vancomycin, and rifampin inhibited all strains, whereas cefpodoxime, cefuroxime, clindamycin, and clarithromycin exhibited very good activity.

Upper Airway Disorders

PATHOPHYSIOLOGY NASOPHARYNGEAL FLORA IN THE FIRST THREE YEARS OF LIFE IN NORMAL AND OTITIS-PRONE CHILDREN Faden H, Brodsky L, Waz MJ, Stanievich J, Bernstein J, Ogra P. Ann Otol Rhinol Laryngol. 1991;100:612-615 Purpose of the Study The study was conducted to establish the types of middle ear bacterial pathogens found in the nasopharyngeal region of a group of normal children. Study Population A total of 110 demographically similar children aged 2 months to 3 years, who lived in the Greater Buffalo, New York, area, were enrolled in a 3-year prospective study of the natural history of otitis media as it relates to the nasopharyngeal bacterial flora. As the study progressed the group was divided into otitis-prone (OP) and non-otitis-prone (NOP) children. Methods The children had at least one visit every 3 months for the evaluation of the nasal passages and ears. They were examined by the same group of investigators for sick visits. At each visit, whether sick or well, cultures from the nasopharynx were obtained. Findings The OP children, even when well, were found to carry middle ear pathogens, Streptococcus pneumonniae, Moraxella catarrhalis, or nontypeable Haemophilus influenzae, at a rate statistically higher than the NOP group. When they were ill with a respiratory illness, the recovery rate of the same pathogens was again found to a greater degree in the OP children than the NOP ones. Of interest, H influenzae type B was not isolated in any nasopharyngeal culture. Conclusions The study is in general agreement with other published accounts, but the reason for this chronic carriage rate of middle ear pathogens in OP children remains unknown.

Secretory IgA-, IgG- and C3b-coated bacteria in the nasopharynx of otitis-prone and non-otitis-prone children.

The proportions of secretory IgA (SIgA)-, IgG- and C3b-coated bacteria obtained from a well-defined area on the posterior wall of the nasopharynx (NPH) close to the Eustachian tube were determined. Samples taken from 25 otitis-prone (OP) and 25 non-otitis-prone (NOP) children with normal serum levels of IgA and IgG were evaluated using an immunofluorescence assay. Both groups harboured significantly more nasopharyngeal bacteria coated with IgG than with SIgA (p < 0.001). The OP children had significantly fewer SIgA-coated bacteria (p < 0.05) but more C3b-coated bacteria (p < 0.01) in the NPH than the NOP children had. No significant difference was noted between the two groups regarding IgG coating. The occurrence of Branhamella catarrhalis in the NHP was more pronounced in the OP group (p < 0.05). No significant differences in the occurrence of other middle ear pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Staphylococcus aureus) or quantitative dominance of pathogens were noted between the two groups. Deficiency in SIgA coating of the nasopharyngeal bacteria may contribute to the otitis-prone condition.

Development of a polymerase chain reaction-probe test for identification of Alloiococcus otitis.

A rapid polymerase chain reaction test was developed for specific identification of the human middle ear pathogen Alloiococcus otitis. Primers for the enzymatic amplification reaction were designed from highly specific sequences within the 16S rRNA gene. In addition, a confirmatory test based on hybridization of the polymerase chain reaction products to a specific internal probe was developed.

Abundant Attachment of Bacteria to Nasopharyngeal Epithelium in Otitis-Prone Children

Attachment of bacteria to nonciliated cells of the nasopharyngeal epithelium was evaluated by immunofluorescence assay in 25 otitis-prone and 25 non-otitis-prone children undergoing ear, nose, or throat surgery under general anesthesia. The bacterial findings were analyzed simultaneously, both qualitatively and quantitatively. In otitis-prone children, there was a significant preponderance of epithelial cells having greater than 50 attached bacteria (P less than .001) and of epithelial cells with attached Streptococcus pneumoniae and Haemophilus influenzae (P less than .05). Also, the occurrence of Branhamella catarrhalis in the nasopharynx was more pronounced in the otitis-prone group (P less than .05). No significant differences in the occurrence of other middle ear pathogens or quantitative dominance of pathogens were noted between the two groups. Abundant attachment of pathogens to the epithelial cells close to the nasopharyngeal orifice of the eustachian tube is of a significant factor for the development of the otitis-prone condition.

Bacterial attachment in vivo to epithelial cells of the nasopharynx during otitis media with effusion.

Epithelial cells were obtained by swabbing the posterior wall of the nasopharynx (NPH) of 15 patients (age one to 6 8/12 years; eight males, seven females) undergoing ENT-surgery under general anaesthesia for otitis media with effusion (OME). Individually matched, ear healthy children served as controls. Bacteria attached to the non-ciliated cells were calculated according to a method described. Furthermore, quantitative and qualitative bacteriological analyses were performed on samples obtained from mucoid middle ear effusion material as well as from the NPH. All patients and controls harboured middle ear pathogens (S. pneumoniae, H. influenzae, B. catarrhalis, or S. aureus) in the NPH. Only 33 per cent of the patients harboured middle ear pathogens in the middle ear effusion and the same pathogen was invariably found in the corresponding NPH. Attachment of bacteria to the non-ciliated cells of the NPH diminished significantly with growing age in the ear healthy control group but not in the OME group. OME is closely correlated to the presence of middle ear pathogens in the NPH and to attachment of bacteria to the epithelial cells in the NPH.

Adherence of Haemophilus influenzae to middle ear mucosa injured by killed H. influenzae.

Repetitive acute otitis media is due to recurrent bacterial infection of middle ear superimposed on chronic otitis media with effusion. Endotoxin, one of the constituents of Haemophilus influenzae, is present in some cases in the middle ear effusion of otitis media with effusion and has been demonstrated experimentally to damage the middle ear mucosa. The aim of this study was to determine the effect of killed H. influenzae on the adherence of H. influenzae and H. parainfluenzae to the middle ear epithelial cells. The numbers of adherent organisms per epithelial cell in ears inoculated previously with killed H. influenzae or with normal saline (0.9% NaCl) were compared. Prior middle ear inoculation of killed H. influenzae enhanced the adherence of H. influenzae to middle ear epithelial cells, but it had little effect on the adherence of H. parainfluenzae. H. influenzae adhered to middle ear epithelial cells in greater numbers than H. parainfluenzae. Results demonstrate that a middle ear pathogen adheres to middle ear epithelial cells presumably damaged by killed H. influenzae, whereas a non-pathogen does not. These findings might partly explain the increased susceptibility of an ear with chronic otitis media with effusion to recurrent infection with H. influenzae.

Nasopharyngeal Flora in the First Three Years of Life in Normal and Otitis-Prone Children

Nasopharyngeal carriage of the three major middle ear pathogens (Streptococcus pneumoniae, nontypeable Hemophilus influenzae, and Moraxella catarrhalis) was evaluated prospectively in a group of 110 children followed up for the first 3 years of life. The findings suggested that nasopharyngeal carriage of middle ear pathogens increases significantly during respiratory illness among the general population of young children; however, otitis-prone children demonstrated a tendency to carry nontypeable H influenzae at an unusually high rate even during health. This propensity to carry nontypeable H influenzae might explain why nontypeable H influenzae is a major cause of recurrent or chronic otitis media.

Is attachment of bacteria to the epithelial cells of the nasopharynx the key to otitis media?

Epithelial cells from the nasopharynx of 42 young healthy individuals were obtained by swabbing. The filtered cellular mixture was stained with acridine orange and bacteria attached to the epithelial cells were counted using a fluorescence microscope. Simultaneously qualitative and quantitative bacteriological analyses were performed. Young individuals (< 2 years) had significantly more attached bacteria than older ones (11–15 years) ( P = 0.0001). The presence of middle ear pathogens in the nasopharynx of young children was significantly more prominent than in the older age groups ( P < 0.001). Attachment of middle ear pathogens to nasopharyngeal epithelial cells of young individuals may predispose to otitis media.

Pharmacotherapy of otitis media.

The clinical manifestations of acute otitis media and otitis media with effusion are the result of abnormal eustachian tube function most often caused by inflammation from infection or allergy. The majority of cases involve bacterial infection of the middle ear caused by Streptococcus pneumoniae, Haemophilus influenzae, or Branhamella catarrhalis. Nearly half of all children will have had at least one episode of acute otitis media by 1 year of age, and over 70% by 3 years of age. The signs and symptoms include pain with rubbing or tugging at the ear, fever, irritability, lethargy, and hearing loss. The primary therapy for acute otitis media and otitis media with effusion is antibiotics with the goal of preventing possible complications and providing symptomatic relief. Amoxicillin remains the initial drug of choice in communities where beta-lactamase-producing strains of the common middle ear pathogens are infrequently isolated. If resistant organisms are prevalent, cefaclor, amoxicillin-clavulanate, or cotrimoxazole should be selected. Adjuvant agents such as decongestants have not been shown to provide additional therapeutic benefit. Children who develop chronic otitis media may require prophylactic antibiotic therapy and insertion of typanostomy tubes.

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.

Secretory IgA-and IgG-coated Bacteria in the Nasopharynx of Children:An immunofluorescence study

Bacterial samples were obtained from the posterior wall of the nasopharynx (NPH) of 18 healthy children (age range 1 to 14 years, 10 males, 8 females) and subjected for immunofluorescence studies using fluorescein-labelled goat anti-human IgG and goat anti-human SIgA antibodies. Quantitative and qualitative bacteriological analyses were performed simultaneously. IgG-coated bacteria in the NPH were observed in 1-year-old subjects and opsonized bacteria seemed to increase in numbers and fluorescence intensity with increasing age. SIgA-coated bacteria appeared later, and intensely fluorescing bacteria were not seen until the age of 3 to 6 years. Thirteen out of the 18 children harboured middle ear pathogens in the NPH, but generally speaking non-pathogens dominated the bacterial flora. Immunoglobulins are of the utmost importance for the mucosal defence system, including protection against bacterial attachment to the epithelial cells (SIgA), and bacteriolysis and opsonization of the bacteria (IgG).

Quantitative analysis of the bacterial findings in otitis media

Qualitative and quantitative bacterial analysis of 200 samples of middle ear effusions collected from patients with current otitis media was performed. When middle ear pathogens (S. pneumoniae, H. influenzae and B. catarrhalis) were found during current acute otitis media or otitis media with effusion infection, the quantity of these bacteria was of the magnitude 10(6)-10(8)/ml and 0-5 x 10(5)/ml effusion material, respectively. Mucopurulent effusion material contained 6 x 10(5)-10(8) bacteria per ml whereas effusion from chronically discharging ears exceeded 10(9) bacteria per ml. Serous effusions did not harbour middle ear pathogens. The appearance of the effusion material was dependent on the number of bacteria involved. Quantification of bacteria in various middle ear effusions offers opportunities to make the diagnosis of various otitis media infections more accurate and readily comparable.

Occurrence of middle ear pathogens in the nasopharynx of young individuals:A quantitative study in four age groups

Colonization of middle ear pathogens (S. pneumoniae, H. influenzae and B. catarrhalis), potential pathogens (S. aureus and coagulase-negative staphylococci) and non-pathogens was determined quantitatively on the posterior wall of the nasopharynx (NPH) of children (four age groups: under 2 years, 2-5 years, 6-10 years and 11-15 years). None of the 90 individuals examined was suffering at the time of bacterial sampling from acute otitis media (AOM), sinusitis, or tonsillitis. All individuals under 2 years of age harboured middle ear pathogens in the NPH, but only 40% of the individuals of the oldest age group (p less than 0.001). Furthermore, in the youngest group, 57% of the cases had pathogens in the NPH, which completely dominated the bacterial flora, i.e. constituted more than 90% of the total bacterial count when calculated as CFU/cm2. The corresponding count in the oldest age group was only 20% (p less than 0.01). One important reason for the high incidence of AOM among young children in particular seems to be the noticeable accumulation of middle ear pathogens in huge quantities in the NPH in this age group.

Recovery of a unique bacterial organism in human middle ear fluid and its possible role in chronic otitis media.

The middle ear fluids of 10 children with persistent otitis media with effusion (OME) were found to contain an unclassified, slow-growing, gram-positive organism. Large gram-positive cocci, often present as diplococci or tetrads, were readily seen in each effusion. Culture of the fluid on a blood agar plate required 2 to 5 days of incubation at 37 degrees C and yielded a slow-growing coccus in pure culture in 70% of cases and in mixed culture in 30% of cases. The organism in question was unique and could be distinguished from aerococci, gemellas, enterococci, and micrococci. It grew in 6.5% saline and on bile esculin agar. It did not grow at 45 degrees C or anaerobically. It was uniformly catalase and hippurate positive. It gave negative reactions with tellurite, tetrazolium, and pyruvate and did not utilize any of the carbohydrates tested. Reactions to bile esculin were variable. The episodes of OME associated with the bacterium in question were asymptomatic, had been present from 1 to 8 months, and occurred in children who had previously experienced OME. The middle ear fluids were typically serous or seromucinous and contained inflammatory cells. The data suggest that the gram-positive coccus is a newly described middle ear pathogen and may be responsible, in part, for persistent middle ear effusion. The characteristically slow growth of the organism in vitro could hinder recovery of the organism from clinical specimens and may therefore have prevented its earlier recognition.

The Bacterial Flora of the Nasopharynx, with Special Reference to Middle Ear Pathogens:A Quantitative Study in Twenty Children

Quantification of middle ear pathogens (S. pneumoniae, H. influenzae and B. catarrhalis) and potential pathogens (S. aureus and coagulase-negative staphylococci) adhering to the posterior wall of the nasopharynx was performed in 20 patients of whom 5 were suffering from secretory otitis media (SOM), 5 from recurrent attacks of acute otitis media (rAOM), 5 from attacks of upper respiratory infection (URI) and 5 from blocked nose (BN). While the patients were under general anesthesia a glass cylinder (diameter 1.3 cm) was pressed against the posterior wall of the nasopharynx and swabs were taken from the mucosa delineated by the glass tube. Quantification of the bacteria was performed using blood and chocolate agar plates. Total bacterial counts ranged between 2.6 x 10(4)CFU/cm2 and 4.0 x 10(8)CFU/cm2. In the rAOM group, 4 out of 5 children had bacterial counts in the nasopharynx which constituted of 95% pathogens. Coagulase-negative staphylococci never exceeded 1.9 x 10(5)CFU/cm2.

Colonization of middle ear pathogens in the nasopharyngeal opening of the Eustachian tube during secretory otitis media.

Colonization of middle ear pathogens (S. pneumoniae, H. influenzae and B. catarrhalis) in the nasopharyngeal opening of the Eustachian tube (NO) was charted in 94 patients (170 ears) suffering from secretory otitis media (SOM). Subsequent determination of microorganisms in the middle ear effusion was performed. 76% of the patients had colonization of pathogens in the NO, while pathogens colonized the middle ear cavity (MEC) in 30% of the cases. Predominant pathogen was S. pneumoniae, followed by B. catarrhalis and H. influenzae. When colonizing the MEC, there was a 100% correlation to NO regarding B. catarrhalis, 81% correlation for S. pneumoniae and 57% for H. influenzae. S. aureus and/or coagulase-negative staphylococci were only occasionally found in the NO. Accumulation of a sticky glue effusion material in the middle ear cavity may serve as a barrier against ascending pathogens from the nasopharynx.

How Long Do Middle Ear Pathogens Survive in Mucoid Effusion Material?

Middle ear pathogens (S. pneumoniae, H. influenzae, B. catarrhalis, S. aureus and coagulase-negative staphylococci) were injected into 28 samples of mucoid effusion materials taken from 17 patients suffering from secretory otitis media. In every case the effusion material was sticky, hydrophilic and thick and contained no bacteria. S. pneumoniae and H. influenzae survived for only 1-2 days in mucoid effusion material incubated at 37 degrees C, while B. catarrhalis and staphylococci survived for at least 18-36 days when incubated in this medium. It seems that mucoid effusion material filling the middle ear cavity during secretory otitis media has a dual function in providing protection against middle ear infections. Thanks to its physical properties the effusion material hinders bacteria from ascending from the nasopharynx and is a poor substrate for some microorganisms. In contrast, mucoid effusion material is a superior medium for B. catarrhalis and staphylococci.

Relapse of acute purulent otitis media: antibiotic sensitivities of nasopharyngeal pathogens.

The present investigation was conducted to find out if a relapse of acute purulent otitis media is associated with a decreased sensitivity of nasopharyngeal pathogens to commonly used antimicrobial agents. All but one of 63 children with relapse included in this study yielded one or more of the classical middle ear pathogens (Streptococcus pneumoniae, Haemophilus influenzae, Branhamella catarrhalis, S. pyogenes) in their nasopharynx (NPH) secretions. S. pneumoniae was the predominating isolate from NPH (71% of the patients) as well as from middle ear effusion (53%). At a control visit 4 weeks after the start of antibiotic therapy, 91% were NPH carriers of potential pathogens and S. pneumoniae was still the most common isolate (53%). Beta-lactamase was produced by 55% of B. catarrhalis isolates from the NPH specimens on the first visit, but only by 33% of B. catarrhalis isolates on the control visit. Two NPH isolates of H. influenzae produced beta-lactamase. One isolate of S. pneumoniae (serotype 18) was intermediately sensitive to phenoxymethylpenicillin. Generally low MICs were found for erythromycin and cefaclor. H. influenzae isolates were generally sensitive to ampicillin in vitro, but only 1 isolate was fully sensitive to erythromycin. B. catarrhalis isolates were uniformly sensitive to doxycycline and trimethoprim/sulphamethoxazole. No tolerance to penicillin was demonstrated in S. pneumoniae and H. influenzae. The present data indicate that the relapse of acute otitis media is not associated with development of tolerance or resistance to therapeutic antimicrobials commonly used.

Presence of Respiratory Viruses in Middle Ear Fluids and Nasal Wash Specimens From Children With Acute Otitis Media

During a 28-month period, 84 children with acute otitis media were studied by viral and bacterial cultures of middle ear fluid and viral cultures of nasal lavage fluid. Viruses were isolated from the middle ear fluid of 17 (20%) patients. Evidence of viral infection was demonstrated by positive viral cultures of middle ear fluid and/or nasal lavage fluid in 33 (39%) patients. Rhinovirus in one patient and influenza b virus in another were the only pathogens isolated. Influenza virus, enterovirus, and rhinovirus were the most common viruses found in middle ear fluids. Parainfluenza virus, adenovirus, and respiratory syncytial virus were found less often. In 82% of cases, the virus isolated from middle ear fluid was also isolated from nasal lavage fluid, but only 44% of viruses found in nasal lavage fluid were also found in middle ear fluid. Mixed bacterial and combined viral-bacterial infections were common. Only 15% of patients had no pathogen isolated from middle ear fluids. Using tissue culture techniques, we demonstrated that enterovirus and rhinovirus are also common middle ear pathogens. Our data reemphasize the significance of viruses as etiologic agents of acute otitis media and propose several questions regarding the viral-bacterial interactions and the types of viruses involved in the pathogenesis of the disease.