The role of anaerobic bacteria in acute and chronic mastoiditis

A child with recurrent otitis media due to Bacteroides thetaiotaomicron

Brain abscess remains a life-threatening condition. Here, we are reporting a case of brain abscess due to Bacteroides thetaiotaomicron in a previously known case of recurrent otitis media. A 15 years old boy with a history of recurrent otitis media presented with the complaints of right otalgia, headache and fever. Computed Tomography (CT) brain and neck revealed fluid filled right middle ear cavity with bony destruction along the inner cortex of right temporal bone. The abscess was drained and culture showed growth of Bacteroides thetaiotaomicron. This report illustrates the importance of MALDI-TOF MS in the species level identification of anaerobes thereby facilitating the selection of appropriate and prompt adjuvant antibiotic therapy. This timely identification thus led to a favourable outcome in an era of increasing antimicrobial resistance.

Spectrum and treatment of anaerobic infections

Anaerobes are the most predominant components of the normal human skin and mucous membranes bacterial flora, and are a frequent cause of endogenous bacterial infections. Anaerobic infections can occur in all body locations: the central nervous system, oral cavity, head and neck, chest, abdomen, pelvis, skin, and soft tissues. Treatment of anaerobic infection is complicated by their slow growth in culture, by their polymicrobial nature and by their growing resistance to antimicrobials. Antimicrobial therapy is frequently the only form of therapy needed, whereas in others it is an important adjunct to drainage and surgery. Because anaerobes generally are isolated mixed with aerobes, the antimicrobial chosen should provide for adequate coverage of both. The most effective antimicrobials against anaerobes are: metronidazole, the carbapenems (imipenem, meropenem, doripenem, ertapenem), chloramphenicol, the combinations of a penicillin and a beta-lactamase inhibitors (ampicillin or ticarcillin plus clavulanate, amoxicillin plus sulbactam, piperacillin plus tazobactam), tigecycline, cefoxitin and clindamycin.

Children hospitalized due to acute otitis media: how does this condition differ from acute mastoiditis?

OBJECTIVES

To evaluate the clinical picture and microbiological findings of children hospitalized due to acute otitis media and to analyze how it differs from acute mastoiditis.

METHODS

A retrospective review of the medical records of all children (0-16 years) hospitalized due to acute otitis media in the Department of Otorhinolaryngology at the Helsinki University Hospital, between 2003 and 2012. Comparison with previously published data of children with acute mastoiditis (n=56) from the same institute and period of time.

RESULTS

The most common pathogens in the children hospitalized due to acute otitis media (n=44) were Streptococcus pneumoniae (18%), Pseudomonas aeruginosa (16%), Streptococcus pyogenes (14%), and Staphylococcus aureus (14%). One of the most common pathogens of out-patient acute otitis media, Haemophilus influenzae, was absent. Otorrhea was common in infections caused by S. pyogenes and otorrhea via tympanostomy tube in infections caused by P. aeruginosa. In children under 2 years-of-age, the most common pathogens were S. pneumoniae (43%), Moraxella catarrhalis (14%), and S. aureus (7%). S. pyogenes and P. aeruginosa were only found in children over 2 years-of-age. Previous health problems, bilateral infections, and facial nerve paresis were more common in children hospitalized due to acute otitis media, compared with acute mastoiditis, but they also demonstrated lower CRP values and shorter duration of hospital stay. The number of performed tympanostomies and mastoidectomies was also comparatively smaller in the children hospitalized due to acute otitis media. S. aureus was more common and S. pneumoniae, especially its resistant strains, was less common in the children hospitalized due to acute otitis media than acute mastoiditis.

CONCLUSIONS

Acute otitis media requiring hospitalization and acute mastoiditis compose a continuum of complicated acute otitis media that differs from common out-patient acute otitis media. The bacteriology of children hospitalized due to acute otitis media resembled more the bacteriology of acute mastoiditis than that of out-patient acute otitis media. The children hospitalized due to acute otitis media needed less surgical treatment and a shorter hospitalization than those hospitalized due to acute mastoiditis.

Epidemiological characteristics of infections caused by Bacteroides, Prevotella and Fusobacterium species: a prospective observational study

In order to investigate differences among infections due to Gram-negative anaerobic bacteria (Bacteroides, Prevotella and Fusobacterium spp.), clinical, epidemiological, and microbiological data were collected and evaluated from 206 anaerobic infections. The most frequently isolated species was Bacteroides fragilis. The majority of the cases were intra-abdominal infections (49%) followed by skin and soft tissue infections (24.7%). Logistic regression analysis showed that Bacteroides spp. strains were more often isolated from intra-abdominal infections (p = 0.002), whereas Prevotella spp. were isolated more frequently from cases with shorter duration of hospitalization (p = 0.026), and less frequently from bloodstream infections (p = 0.049). In addition, Bacteroides spp. were associated with coinfection due to Enterobacteriaceae species (p = 0.007), whereas Prevotella spp. were associated with coinfection due to Staphylococcus spp. (p = 0.002). Patients with an infection due to B. fragilis, were more frequently admitted in a general surgical ward (p = 0.017), or have been treated with a 2nd generation cephalosporin before anaerobic infection onset (p = 0.05). Total mortality was 10.9% and was associated with bacteremia (p = 0.026), and hematological (p = 0.028), or solid organ malignancy (p = 0.007). Metronidazole resistance was detected only among Prevotella spp. (16.2%) and B. fragilis group (0.8%) isolates. In conclusion, this study indicated differences between infections due to the most frequently isolated Gram-negative anaerobic species, differences that may affect the design and implementation of empirical antimicrobial chemotherapy guidelines.

Acute mastoiditis in children: a retrospective study of 188 patients

OBJECTIVE

The aim of this study is to define the clinical and bacteriological characteristics of acute mastoiditis (AM) in children in order to optimize diagnostic work-up and treatment.

METHODS

In this retrospective study, 188 children between 3 months and 15 years of age (15±24 months; median±SD) were referred to our pediatric ENT emergency center for AM during a 7-year period (December 2001-January 2008).

RESULTS

Fifty seven percent were male and 43% were female. Clinical follow-up duration was 3.9±0.7 months (mean±SEM). The incidence of AM remained stable during the whole study period. Microbiological samples (n=236) were negative in 33% of cases. The most frequently isolated germs were Streptococcus pneumoniae (51%), Streptococcus pyogenes (11.5%), Anaerobes (6.5%), and coagulase-negative Staphylococcus (6.5%). Paracentesis, puncture of retro auricular abscess under local anesthesia, and peroperative samples all contributed to isolate the involved germ(s). All the patients were hospitalized and received intravenous antibiotics, and 36.2% (n=68) underwent surgery. Several surgical procedures were necessary in 4 cases (2.1%). AM recurrences requiring a second hospitalization were observed in 8 patients (4.3%). The only observed complication was lateral sinus thrombosis (n=6; 3.2%). Surgical failures, requiring more than one surgical procedure, were more frequent in case of: (i) presence of Anaerobes (p≤0.001) or Gram-negative bacteria (p≤0.05) in microbiological samples; (ii) surgical drainage without mastoidectomy (p≤0.001). Recurrences were more frequent in AM due to Streptococcus pneumoniae.

CONCLUSIONS

Based on our findings and on literature data, a protocol was established in order to standardize the management of pediatric AM in our center. The mains points are: no systematic surgery; if surgery is indicated, it must encompass a mastoidectomy; broad-spectrum intravenous antibiotic treatment covering the most commonly involved germs (3rd generation cephalosporin) and secondarily adapted to the results of microbiological samples. If the infection is not controlled after 48 h of intravenous antibiotherapy, a mastoidectomy had to be performed.

The role of anaerobic bacteria in chronic suppurative otitis media in children: implications for medical therapy

This review describes the microbiology, diagnosis and medical management of chronic suppurative otitis media (CSOM) in children highlighting the role of anaerobic bacteria. In studies that employed adequate method for recovery of anaerobic bacteria polymicrobial aerobic and anaerobic flora was isolated from over half of the children with CSOM. The predominant aerobic isolates were Staphylococcus aureus and Pseudomonas aeruginosa and the most frequently isolated anaerobic organisms were Peptostreptococcus, Fusobacterium spp. and pigmented Prevotella and Porphyromonas spp. Several studies illustrated the efficacy of anti-infective agents effective against anaerobic bacteria in the treatment of CSOM. The medical therapy of CSOM should be directed at the eradication of the pathogenic aerobic and anaerobic organisms.

Human infection with Fusobacterium necrophorum (Necrobacillosis), with a focus on Lemierre's syndrome

Human infection with Fusobacterium necrophorum usually involves F. necrophorum subsp. funduliforme rather than F. necrophorum subsp. necrophorum, which is a common pathogen in animals. Lemierre's syndrome, or postanginal sepsis, is the most common life-threatening manifestation. Tonsillitis is followed by septic thrombophlebitis of the internal jugular vein and then a septicemia with septic emboli in lungs and other sites. Recent evidence suggests that F. necrophorum can be limited to the throat and cause persistent or recurrent tonsillitis. F. necrophorum is unique among non-spore-forming anaerobes, first for its virulence and association with Lemierre's syndrome as a monomicrobial infection and second because it seems probable that it is an exogenously acquired infection. The source of infection is unclear; suggestions include acquisition from animals or human-to-human transmission. Approximately 10% of published cases are associated with infectious mononucleosis, which may facilitate invasion. Recent work suggests that underlying thrombophilia may predispose to internal jugular vein thrombophlebitis. Lemierre's syndrome was relatively common in the preantibiotic era but seemed to virtually disappear with widespread use of antibiotics for upper respiratory tract infection. In the last 15 years there has been a rise in incidence, possibly related to restriction in antibiotic use for sore throat.