European Review for Medical and Pharmacological Sciences 2019; 23(1 Suppl.): 27-38 An overview on upper respiratory tract and bacteriotherapy as innovative therapeutic strategy

L.M. BELLUSSI1, F.M. PASSALI2, M. RALLI3, M. DE VINCENTIIS3, A. GRECO3, D. PASSALI1

1Department of Medicine, and Neuroscience, ENT Clinic, University of Siena, Siena, Italy 2Department of Clinical Sciences and Translational Medicine, Tor Vergata University, Rome, Italy 3Department of Sense Organs, Sapienza University of Rome, Rome, Italy

Abstract. – OBJECTIVE: The aim of this re- List of Abbreviations view is to describe the most common recurring URTI: upper respiratory tract infections; AOM: acute otitis and chronic upper respiratory tract infections media; RSV: respiratory syncytial virus; OME: otitis media (URTI) in children and discuss the role of bac- with effusion, SOM: suppurative otitis media. terial interference and bacteriotherapy in their prevention and treatment. MATERIALS AND METHODS: A literature review has been performed on the following topics: acute otitis media, adenoiditis, tonsilli- Introduction tis, rhinosinusitis, microbiotics and the role of bacterial interference, and bacteriotherapy in Recurring and/or chronic / the prevention and treatment of URTI. infections of the upper respiratory tract are ex- RESULTS: Research studies into the charac- teristics of the microbiological flora and its role tremely frequent in the early years of life while in the pathogenesis of URTI have focused on a children are still developing immune properties. single pathogen, on resistance to and ineffective- Immediately after birth, the upper airway rap- ness of therapies, or on the persistence idly becomes colonized by commensal and poten- of bacterial biofilm. Recent evidence supports a tially : within the first year, central role of the existing microbial ecosystem 50 to 100% of infants are colonized by Strepto- in the pathogenesis of respiratory disease. In coccus pneumoniae, and light of this, new therapeutic approaches include 1 the implantation and persistence within the nor- . In general, colonization mal microflora of relatively innocuous “effector” rises gradually and peaks at 2-3 years of life, then bacteria that can competitively exclude or prevent decreases until 15-16 years, eventually increas- the outgrowth of potentially disease-causing bac- ing again in adults older than 65 years2. Although teria. Recently, a retrospective and observational variable, the colonization rates in healthy adults study demonstrated that S. salivarius 24SMB and are lower than those in children. Colonization is a S. oralis 89a nasal spray could be effective in the prevention of recurrent otitis media in a real-life dynamic phenomenon varying not only from de- setting. Other studies have focused on the role of livery, through childhood, adolescence, adult and bacteriotherapy in children with beneficial effects advanced age, but also according to genetic back- in the prevention of URTI. ground variables, socioeconomic conditions and CONCLUSIONS: The results of previous stud- geographic areas3-5. The upper airway is a major ies on the role of bacteriotherapy in paediat- ecological reservoir of bacterial species: as in the ric URTI suggest that the use of bacterial inter- gut, the early pharyngeal microbiome influences ference phenomena through bacteriotherapy is 6 a feasible, safe approach and deserves proper colonization and respiratory tract health . Protec- consideration as a promising therapeutic strat- tive and potentially pathogenic bacteria have been egy against URTI. isolated in populations of healthy children, such as persistent or transient pathogens of the naso- and Key Words oropharynx. These are: Neisseria, OSAS, Children, Snoring, Multidisciplinary ap- proach. pyogenes, Haemophilus influenzae, Staphylococ- cus aureus, Actinomyces, Bacteroides, Prevotel-

Corresponding Author: Massimo Ralli, MD; e-mail: [email protected] 27 L.M. Bellussi, F.M. Passali, M. Ralli, M. de Vincentiis, A. Greco, D. Passali la, Porphyromonas, Peptostreptococci, and Fu- children, such as acute otitis media, adenoiditis sobacterium spp7,8. Pathogens enter the host by and , and rhinosinusitis, and discuss the colonizing the nasopharyngeal mucosal epitheli- role of bacterial interference and bacteriotherapy um, but identifiable disease occurs in only a small in their prevention and treatment. percentage of persons who are colonized. To date, research into the characteristics of the microbiological flora and their role in the patho- Materials and methods genesis of recurring and chronic upper respirato- ry tract infections (URTI) has focused on a single A literature review has been performed on ar- pathogen, on resistance to and ineffectiveness ticles retrieved from PubMed and Scopus on the of antibiotic therapies, or, more recently, on the following topics: acute otitis media, adenoiditis, presence/persistence of bacterial biofilm9. The tonsillitis, rhinosinusitis, microbiotics and the worldwide emergency of bacterial resistance to role of bacterial interference, and bacteriotherapy has led to the need for new methods of in the prevention and treatment of URTI. combating bacterial infections10. This emergency is aggravated by the long delay in the develop- ment of new antibacterial agents. If the design Results of new agents proves to be in the right direction, such progress would not resolve all current resis- Acute Otitis Media tance problems; in addition, it should be remem- Acute otitis media (AOM) is the most common bered that the use of antibacterial agents selects bacterial in young children, with con- not only resistant bacteria but may also negatively sequences on hearing and associated symptoms affect normal bacterial flora even if with differ- that in some cases may also affect behavior and ent degree of interference11. The administration language development14,15. Large amounts of an- of antimicrobial agents disrupts normal human tibiotics are prescribed for this pathology, espe- flora, further reducing our defense against in- cially for those children with recurring episodes. fections12. Modern molecular culture-indepen- The peak incidence of AOM is at 1­2 years of age15. dent approaches to chronic respiratory diseases The majority of AOM episodes occur concurrent- have opened a promising scenario on microbial ly with, or soon after, viral URTI. Chonmaitree et communities associated with the human body al16 found a high prevalence of symptomatic viral and their role in health and diseases, but consen- URTI among young children; >60% of cases were sus does not yet exist on the microbial ecology complicated by AOM and/or otitis media with ef- associated with chronic diseases. Last-century fusion (OME). In addition to young age and im- theories about the mechanisms involved in infec- mature Eustachian tube function, specific viral tious episodes viewed the lymphatic vessels and infection, such as adenovirus, respiratory syncy- the immune cells of the mucosa grouped in the tial virus (RSV), coronavirus and viral load, are specific area named Waldeyer’s ring as the most predictors of URTI complicated by AOM. important line of defense of our body from ex- The risk of developing another episode within ternal attacks. Lymphoid tissue in Waldeyer’s one month after the onset of the primary infection ring structures (namely adenoids, palatine tonsils, is estimated at 35%; in the majority of cases (75%) tubal tonsils and lingual tonsils) is predominantly the new episodes are infections by new bacterial characterized by crypts and mucosal irregulari- strains, suggesting an underlying susceptibility to ties, rendering them more susceptible to antigenic recurrent AOM. The remaining 25% are from ei- responses through the acquired immunity mecha- ther re-infection with the same bacterial strain or nisms. Nowadays, the upper airway microbiome, treatment failure17. including saprophytic, commensal, pathogenic About 5% of children are “prone” to otitis me- bacteria, fungi, and viruses, is considered the first dia, defined as three episodes within a 6-month line of defense of our body; when the inflamma- time span or 4 events within 12 months18. More re- tory response to pathogenic stimuli starts, a sit- cently, the definition of “stringent otitis prone” was uation of disequilibrium or dysbiosis opens the proposed when the clinical diagnosis is confirmed door to clinically evident infection and recurring/ by bacterial culture of the middle ear fluid19. chronic disease 13. The aim of this review is to Bacterial culture confirmation is of the utmost describe the most common recurring and chron- importance: signs and symptoms are often aspe- ic inflammations of the upper respiratory tract in cific and empiric clinical diagnosis doesn’t allow

28 Upper respiratory tract infections and bacteriotherapy differentiation of OME (i.e. the presence of fluid 2. Epidemiologic studies have shown that the risk in the middle ear without signs or symptoms of of S. pneumoniae colonization differs according to acute infection) from AOM, which could limit whether H. influenzae, M. catarrhalis, and Staph- unnecessary antibiotic use and microbial flora al- ylococcus aureus are also present26-28. Bacteri- terations. OME often resolves spontaneously, and um-bacterium interaction may also impact AOM only rarely may insertion of a tympanostomy tube incidence. Simultaneous colonization by multiple be required for fluid drainage20. AOM pathogens is associated with a greater risk Disease etiology and pathogenesis are of AOM than the risk associated with colonization multi-factorial and begin with colonization of by a single AOM pathogen 29,30. Members of the mucosal surfaces in the upper respiratory tract by normal flora, such as alpha-hemolytic streptococ- AOM pathogens21. ci, inhibit the growth of AOM pathogens in vitro31. The most common bacteria associated with Healthy children are more likely than children with AOM are , Haemophi- AOM to be colonized by alpha-hemolytic strep- lus influenzaeand, less often, Moraxella catarrh- tococci32-34. Lower numbers of alpha-hemolytic alis and group A β-streptococci15. These bacteria streptococci have been found in the nasopharynx originate and diffuse from the nasopharynx to the of children who are prone to otitis media compared middle ear cavity by way of the Eustachian tube. with those who are not prone and in those with Secretory otitis media (SOM) is the most com- SOM compared with healthy children15. Collec- mon sequela of AOM; it is characterized by per- tively, these data indicate that certain commensals sistence of effusion in the middle ear cavity20. One influence the risk of AOM pathogen colonization or more of S. pneumoniae, H. influenzae, or M. and the subsequent risk of disease 21. catarrhalis are found in approximately 30% of pa- tients with suppurative otitis media (SOM)15,22. A Adenoiditis/Tonsillitis strong correlation between the nasopharyngeal flo- The adenoids are believed to play a role in ra and middle ear infections has been found. Naso- several infectious and non-infectious pathologies pharyngeal colonization by H. influenzae, S. pneu- of upper airways35. Since the 1980s, it has been moniae and/or M. catarrhalis in the first year of clear that they are implicated in the etiology of life is associated with an increased risk of recurrent OMA36-41, rhinosinusitis36,39,42, adenotonsillitis43 AOM or SOM compared with children who remain and chronic nasal obstruction44,45. The adenoids free of colonization. The factors that influence col- in healthy children contain potential respiratory onization are multiple and not entirely clear. There pathogens43,46. The nasopharynx and adenoids of is no doubt that the local host immune response healthy individuals, unlike subjects with recur- plays an important regulatory role in the traffick- rent URTI, are generally colonized by aerobic ing of pathogens in the upper airway. Other factors and anaerobic microorganisms that are able to in- influencing nasopharyngeal carriage rates are: age, terfere with the growth of potential pathogens47,48. season, type of child day care, number of siblings, Exposure to antimicrobial therapy can alter acute respiratory illness, diet (breast-feeding vs. the colonization patterns and select for resistant bottle-feeding), and sleeping position. In adults, organisms. Production of β-lactamase is one of other factors are implicated: presence of children the major mechanisms of resistance of these or- at home or at the workplace, chronic obstructive ganisms. Maintaining the beneficial effects of pulmonary disease, obesity, immunosuppression, normal flora by avoiding unnecessary exposure allergic conditions, and acute sinusitis2. to antimicrobial therapy may be a useful tool in In children with recurrent AOM potential preventing colonization of the adenoids and/or pathogens may constitute > 90% of the total bacte- tonsils by potential pathogens35. rial count15,22. In contrast, among healthy children Adenoids are liable to inflammatory changes viridans streptococci are predominant23. Data from (viral, allergic) and frequently are infected con- Syrjanen et al24 show that S. pneumoniae carriage comitantly with the tonsils. Acute adenoiditis is lower during health (13-43%) than during AOM may occur alone or in association with rhinitis or episodes, reaching 97-100% carriage in pneu- tonsillitis. Chronic adenoiditis may result from mococcal AOM. Otitis-prone children tend to be repeated acute attacks or from persistent infec- colonized more often than non-otitis-prone chil- tion. Adenoid hypertrophy is defined as an en- dren25. In addition, nasopharyngeal colonization largement of the adenoids, which may be simple with antibiotic-resistant bacteria is associated with or inflammatory, and may be linked to infection. an increased incidence of unresolved otitis media Recurring adenotonsillitis is often a bacterial-vi-

29 L.M. Bellussi, F.M. Passali, M. Ralli, M. de Vincentiis, A. Greco, D. Passali ral illness35. Along with recurring tonsillitis, ad- such as S. pneumoniae, H. influenzae and M. ca- enoid hypertrophy and recurring adenotonsillitis tarrhalis, can, however, occur in healthy subjects; constitute adenotonsillary disease characterized it increases significantly in children during respi- by persistent bacterial infection35. ratory diseases and in sinusitis8,34. The nasophar- Periodic episodes of and upper airway ynx of healthy individuals is generally colonized obstruction are the major symptoms of adenoid- by relatively non-pathogenic aerobic and anaer- itis and recurring tonsillitis. obic organisms48,62, some of which are able to in- Recurring or chronic of the ad- terfere with the growth of potential pathogens63. enoids and faucial tonsils leads to chronic activa- This phenomenon is called bacterial interference8. tion of the cell-mediated and humoral immune re- These organisms include, amongst others, aerobic sponses, resulting in hypertrophy of the lymphoid microorganisms such as alpha-hemolytic strepto- tissue. This hypertrophic tissue is the cause for cocci (mostly Streptococcus mitis and Streptococ- the prominent clinical symptoms: obstruction of cus sanguinis)64 and anaerobic bacteria (Prevotella the upper airways, snoring, and sleep apnea for melaninogenica and Peptostreptococcus anaer- adenoiditis or sore throat, dysphagia and halitosis obius)65. The absence of interference between for recurring tonsillitis49. organisms may explain the greater possibility of In adenoids and tonsils, bacteria, mostly Staph- recruiting pathogens in these children. The colo- ylococcus aureus, Haemophilus sp., and Strepto- nization of interfering organisms can play a role in coccus sp., persist predominantly intracellularly preventing colonization by pathogens and the de- and within mucosal biofilms50. As with recurring velopment of URTI, including sinusitis. Exposure tonsillitis and adenoiditis, the most likely mecha- to direct and indirect smoking can increase oral nism for pathogenesis is the endogenous reactiva- colonization with pathogenic bacteria and decrease tion of these persistent pathogenic bacteria51,52. In the number of organisms that interfere with their recent research, biofilm formation was identified growth. The flora of smokers contains fewer aer- as playing a pivotal role in the etiology of numer- obic and anaerobic organisms with interfering ca- ous chronic otorhinolaryngologic infections, such pability and more potential pathogens as compared as chronic rhinosinusitis, chronic otitis media, with nonsmokers66. The high number of pathogens and adenotonsillar disease, which do not respond and the low number of interfering organisms found to conservative antimicrobial treatment49,53,54. in the nasopharynx of smokers reverts to normal Bacteria in biofilms are surrounded by a car- levels after complete cessation of smoking67. bohydrate-containing matrix on or within the ad- The pattern of many URTI, including sinus- enotonsillar epithelium, and communicate with itis, evolves in different phases. The initial phase each other by a process called quorum sensing is often a viral infection that usually lasts up to 10 (QS), which responds to the density of cell pop- days, after which it manifests a complete recovery ulations55,56. Biofilms in the adenoids may act as in most subjects68. However, a small number of reservoir for chronic otitis media and chronic rhi- patients with viral sinusitis may develop second- nosinusitis57. ary acute bacterial infection8. This is generally Thus, adenoidectomy is shown to be a plausi- caused by optional aerobic bacteria (i.e., S. pneu- ble therapy for two diseases: as surgical removal moniae, H. influenzae, and M. catarrhalis)8, also of an infectious source in the nasopharynx and as called “the infernal trio”69. The maxillary sinus first-line therapy for medically refractory, uncom- has 26% of S. pneumoniae, 28% of H. influenzae plicated paediatric rhinosinusitis58,59. and 6% M. catarrhalis, plus 8% of S. aureus70. Conservative treatment of moderate grades of If the episode does not resolve, anaerobic bacte- hypertrophy with bacterial compounds must con- rial flora becomes predominant over time8. The sider these bacterial persistence strategies. dynamics of these changes in bacterial flora have been demonstrated by performing serial cultures Rhinosinusitis in patients with maxillary sinusitis71. It could be The upper respiratory tract, including the na- assumed that chronic sinusitis is an extension of sopharynx, serves as a reservoir for pathogens ca- an acute non-resolved infection8. The acute exac- pable of causing URTI, including rhinosinusitis60. erbation of chronic sinusitis is a sudden worsen- Potential pathogens can relocate during a viral re- ing of chronic sinusitis (worsening of symptoms spiratory infection, from the nasopharynx into the in progress or the appearance of new symptoms). sinus cavity, causing a sinusitis61. The nasopharyn- Epithelial cells constitute the first barrier to geal carriage of upper respiratory tract pathogens, pathogenic agents such as viruses or bacteria.

30 Upper respiratory tract infections and bacteriotherapy

Goblet cell mucus secretion prevents the microor- the respiratory microbial community can con- ganisms from sticking to the epithelial cells, thus tribute to the acquisition of new bacterial or viral preventing them from entering the human body. pathogens, the carriage of more potent pathogenic The microorganisms trapped in the mucus are me- bacteria, or a viral co-infection. chanically removed by cilia movements71. It may Subsequently, imbalances in the ecosystem happen that with the progress of the pathogenic may result in excessive growth and invasion of process there is a transient increase in pressure pathogenic bacteria, causing inflammatory or in the sinus cavity due to accumulation of mucus. invasive diseases, particularly in children with Then subsequently, a “negative pressure” may immature immune systems81. Colonization of this develop due to an alteration of sinus ventilation niche is therefore a crucial step in the pathogen- with a rapid absorption of oxygen by the mucosa esis of respiratory disease82. In 1960, Hardin ar- cells72. Such an event worsens local congestion, gued that completely competitive species cannot promotes mucus retention, compromises normal colonize the same ecological niche, indicating gas exchange, reduces both oxygen and pH, pre- that one microorganism has the possibility of ful- vents infectious material and inflammatory debris ly extinguishing another. However, the concept of from occurring, and increases the risk of a second colonization is more complex and dependent on bacterial infection73-76. several factors. For example, skin and any muco- sal surface of the body are colonized directly after birth by a wide range of bacteria82. These bacteri- Discussion al communities evolve into a complex ecosystem during the first years of life, varying considerably Microbiotics and the Role among individuals and over time83,84. of Bacterial Interference Alpha-streptococci dominate the normal flora Recent evidence supports the hypothesis that in the upper respiratory tract and have been the the microbiota of the skin and mucous mem- bacteria attracting the most attention in bacteri- branes constitutes a “superorganism”77. Mutual al interference. Most alpha-streptococci have the benefits for the host and microbes are numerous: ability to emit bacteriocins. These are extracel- microbes utilize a nutrient-rich environment, that lularly released toxins produced by the bacteria is of the host, but in return they play a key role 85 that are able to selectively kill other bacteria. in providing a barrier against potential patho- Some bacteria release bacteriocins with a broad gens. Understanding the interactions within the spectrum, and others release bacteriocins with a human “superorganism” and their consequences very narrow spectrum. Studies have shown that for health and illness requires detailed informa- bacteriocin production is a significant ecological tion on the composition of the microbiome that determinant in colonization. Nearly all-oral al- constitutes the many and distinct ecosystems of pha-streptococci release inhibitory substances86, the human body. but bacterial interference can also occur by dif- The upper respiratory tract is the reservoir of ferent mechanisms such as competition for sites a community of potential and pathogenic patho- at the epithelial cells, competition for specific nu- gens including Streptococcus pneumoniae (pneu- trients, and production of substances that change mococcus), Haemophilus influenzae, Moraxella the pH, like hydrogen peroxide7,87. catarrhalis and , which The microbiome of the upper respiratory tract under certain circumstances become pathogenic niche seems to be influenced by the host genetic agents responsible for infectious diseases78,79. background, age, and environmental factors such In order to cause respiratory diseases, the as social status, antibiotic use, vaccination, sea- bacteria must first colonize the nasopharyngeal sonality, cigarette smoking, social contacts, and niche. The colonization of this niche is a complex number of siblings2,24. Studies88 have shown a de- dynamic process that involves the acquisition and crease in normal flora after antibiotic treatment elimination of species, interactions between mi- in URTI. crobes and between microbes and host, and in- A decreased number of alpha-streptococci, terference by environmental factors. In a state of with interfering efficacy against beta-streptococ- equilibrium, this ecosystem, understood as part ci, have also been found on the tonsils of patients of the “human microbiome”, is presumed to play with recurrent streptococcal pharyngo-tonsillitis, an important beneficial role for the person who compared with healthy individuals89. Grahn and plays the role of host80. However, imbalances in Holm90, in a study of an outbreak of streptococcal

31 L.M. Bellussi, F.M. Passali, M. Ralli, M. de Vincentiis, A. Greco, D. Passali tonsillitis in an apartment house area, have shown less bacteria to counteract pathogenic organisms, that individuals with interfering alpha-strepto- is an alternative and promising way of combating cocci on their tonsils less often acquired strepto- bacterial infections12. coccal pharyngo-tonsillitis than patients lacking these bacteria. Lower numbers of alpha-strepto- The Role of Bacteriotherapy cocci have been found in otitis-prone children The worldwide emergency of bacterial resis- compared with non-otitis prone children33, and tance to antibiotics has led to the need for new in patients with secretory otitis media compared methods of combating bacterial infections10,12. with healthy children34. Tano et al31 and Brook This emergency is aggravated by the long delay in and Gober11 recently found that alpha-strepto- the development of new antibacterial strategies12. cocci in children with recurrent OMA and SOM If the design of new agents proves to be in the had less inhibiting activity against pneumococci right direction,such progress would not solve all and H. influenzae compared with alpha-strep- current resistance problems12. Penicillin-specif- tococci isolated from healthy children. Addi- ic antibiotic therapies99 of streptococcal pharyn- tionally, site-specific factors and characteristics geal infections, in line with current therapeutic of the microorganism itself also play a role. By recommendations and guidelines, fails in about colonizing a niche, a microbe should be able to 35% of treatments: alpha-streptococci bacteria survive local clearance mechanisms (i.e., mucus, are believed to play an important role in preven- ciliae, etc.), attach to the epithelium, rely on lo- tion, colonization, and subsequent infection as a cally available nutrients, and bypass surveillance part of beta-hemolytic streptococci, and their ab- by the host immune system82. Another essential sence in the 3 weeks following antibiotic therapy condition for colonization is to outcompete in- may favor recurrence of episodes and, therefore, habitants that were already present in the upper a failure of treatment100. While targeting resistant respiratory tract91,92. S. pneumoniae, H. influen- bacteria, antibacterial agents also disrupt nor- zae, M. catarrhalis are etiologic agents common- mal human flora, further reducing our defenses ly recognized in URTI and the colonization by against infection12 and, more generally, negatively these species is also very common under healthy affecting normal bacterial flora101. circumstances, with a high colonization rate es- The accessible surfaces of the skin, spleen cav- pecially in children2,26,93-96. However, bacterial ities, upper respiratory tract, gastrointestinal tract commensals are thought to play an important role and vagina of healthy vertebrates are colonized by in preventing respiratory and invasive disease82. microbes immediately after birth102. The process is Sanders et al47 and later Grahn et al97 showed a dynamic, orderly succession of microbial acquisi- that some alpha-streptococci may have an inhib- tions and site-specific eliminations102. Collectively iting capacity on group A streptococci in vitro. known as the normal microflora or indigenous mi- These data support the importance of bacterial crobiota, these microbes are the body’s first line of interference in maintaining the balance between defense against pathogenic invasion102. resident flora and pathogenic microorganisms2. The basis of replacement therapy is the im- Since these colonizing microorganisms share the plantation and persistence within the normal mi- natural niche with other non-pathogenic microor- croflora of relatively innocuous “effector” bacte- ganisms, it is probable that these species interact ria that can competitively exclude or prevent the with each other even in the absence of pathology. outgrowth of potentially disease-causing bacte- Microorganisms compete for nutrients and space, ria, without significantly disturbing the balance and when microorganisms overwhelm the native of the existing microbial ecosystem102. saprophytes of that niche, they can colonize; da An early attempt to recolonize the high respira- Lilja et al98 documented beta-hemolytic strepto- tory tract ecosystems was documented by Sprunt cocci in tonsillary epithelial cells of patients with and Leidy103, who reported that a single inocula- acute tonsillitis symptoms, as opposed to those tion of intensive-care infants with alpha-strepto- found in asymptomatic patients, where these bac- cocci isolated from normal flora, in order to avoid teria did not adhere to the epithelial cells but were excessive growth of pathogens, helped restore the found only on the surface mucous layer. balance of microflora of most of the infants within Maintaining normal pharyngeal flora can con- 48-72 hours; the authors concluded that this ap- tribute to preventing or reducing recurrent in- proach was safe in the neonatal population. Fur- fections7 or preventing colonization by potential ther studies104-106 evaluated the use of inoculation pathogens7,14. Bacteriotherapy, the use of harm- of the pharyngeal niche with an alpha-streptococ-

32 Upper respiratory tract infections and bacteriotherapy ci pool, in order to prevent relapsed streptococcus tial diagnosis, particularly with respect to otitis pharyngitis. Alpha-streptococci are significantly media with effusion. Moreover, AOM therapy is reduced in subjects suffering from pathologies controversial; many guidelines suggest watchful in the pharyngeal district107 and, conversely, the waiting for mild-to-moderate episodes in children presence of this bacterial family is associated with aged >2 years. However, in clinical practice, anti- a significant reduction in the risk of recurrent in- biotics are frequently prescribed, ignoring guide- fectious diseases in the pharyngeal district108. The lines and their underlying precepts109. Prevention inoculation agent of alpha-streptococci was used of recurrent AOM is even more debated. At pres- in these studies because patients treated with an- ent, no evidence on proposed treatments, conven- tibiotics often have pharyngeal flora that becomes tional and otherwise, is definitively convincing. completely deregulated with the likely deficiency A randomized, double-blind, placebo-con- of alpha-streptococci, which have an interfering trolled clinical trial on efficacy and tolerability of activity against beta-hemolytic streptococci. intranasal administration of Streptococcus sali- Roos et al104 conducted a randomized, double varius 24SMB was conducted in the treatment blind, placebo-controlled study that enrolled 36 pa- of acute otitis in children with a history of acute tients with relapsing streptococcal tonsils, who first recurrent otitis media 110. The study recruited 100 underwent antibiotic therapy for 10 days; 19 patients patients aged between 1 and 5 years with a history were then treated with an oral spray comprising 4 of acute recurrent otitis media (3 episodes in the strains selected from alpha-streptococci, and 17 pa- previous 6 months or 4 episodes in the previous 12 tients received placebo. None of the patients in the months with the last episode in the previous 2-8 intervention group presented a new episode of ton- weeks) and intranasally administered S. salivarius sillitis during the 3-month follow-up period, while 24SMB (n=50) or placebo (n=47) twice daily for 5 7 of 17 patients in the control group had a tonsillitis days per month for 3 consecutive months. Partici- episode (p <0.05); after 3 months of follow-up, 1 pa- pants were followed for 6 months (3 months each tient in the first groupvs. 11 in the control group pre- treatment and follow up). Treated children were sented an episode of tonsillitis. The authors suggest twice as likely not to manifest acute otitis media that recombination with alpha-streptococci offers a at follow up compared to children in the placebo new way of lowering the rate of recurrence in strep- group (30.0% vs. 14.9%; p=0.076). In addition, the tococcal pharyngeal infections. number of children who received antibiotics during Roos et al105 extended their research with a ran- the study period was lower in children treated with domized, double-blind, placebo-controlled, multi- S. salivarius 24SMB compared to those who re- center study involving 130 patients with recurrent ceived placebo. Compared with children who were episodes of streptococcal pharyngeal tonsillitis. not colonized by S. salivarius 24SMB after treat- Patients received antibiotics for 10 days, followed ment, the number of colonized children who ex- by 5 days of topical spray therapy with alpha-strep- perienced any acute otitis was significantly lower. tococci in the intervention group vs. placebo in Similar results were observed considering antibi- the other group. Clinical recurrences (bacteriolog- otic treatment; the number of colonized children ically verified) in the treatment group of patients using antibiotics was significantly lower compared were 2%, vs. 23% of patients treated with place- with non-colonized children. This study, designed bo (p<0.004). The authors conclude that the spray in part to evaluate a nasal delivery device, revealed treatment with alpha-streptococci, used for at least the ability of S. salivarius 24SMB nasal spray to 5 days, significantly reduces the pharyngo-tonsilli- reduce the risk of AOM in children110,111. tis infectious recurrence episodes. Recently, a retrospective and observational Falck et al104 conducted a randomized, dou- study demonstrated that S. salivarius 24SMB and ble-blind, placebo-controlled, multicenter study S. oralis 89a nasal spray could be effective in the involving 342 tonsillitis patients treated with an- prevention of recurrent AOM in a real-life setting. tibiotic therapy for 10 days, then segmented into S. salivarius 24SMB and Streptococcus oralis 89a treatment with topical alpha-streptococci (n=189) nasal spray was administered to 159 children af- and placebo control (n=93). At 75-day follow-up, ter the first AOM episode; 108 children received recurrence rates were treatment group 19% and no bacteriotherapy and served as control. Active control group 30% (p=0.037). No serious adverse treatment consisted of 3 monthly courses: 2 puffs events were reported. per nostril twice/day for a week. The intervention Diagnosis of AOM requires adequate expe- group showed a significant reduction of AOM epi- rience and procedure to ensure precise differen- sodes in comparison with controls (p<0.0001). No-

33 L.M. Bellussi, F.M. Passali, M. Ralli, M. de Vincentiis, A. Greco, D. Passali tably, all actively treated children with the highest Sources of Funding AOM recurrence had a reduction of recurrence, This work was supported by the Italian Society of Rhi- whereas only 50% of the control group children nology. The sponsor provided financial support for costs had reduced recurrent AOM (p<0.0001)112. related to the publication of this article. The sponsor was Interference between normal flora and patho- not involved in the study design, in the collection and in- gens is not limited to acute streptococcal pharyn- terpretation of data, in the writing of the study, or in the gotonsillitis and acute otitis media. Brook and decision to submit the article for publication. Gober113 have shown that the nasopharyngeal flo- ra and nasal flora of non-sinusitis-prone children contain more aerobic and anaerobic organisms Conflict of Interests with interfering capacity compared with the flora The authors declare that they have no conflict of interest. of sinusitis-prone children. The results of these studies suggest that the use of bacterial interference phenomena through bacte- References riotherapy is a feasible, safe approach and deserves proper consideration as a therapeutic strategy. A 1) Raymond J, Le Thomas I, Moulin F, Commeau A, Gendrel basic concept for bacteriotherapy is the persistence D, Berche P. Sequential colonization by streptococ- cus pneumoniae of healthy children living in an in normal microflora of relatively harmless “effica- orphanage. J Infect Dis 2000; 181: 1983-1988. cious” bacteria, which can competitively exclude 2) Garcia-Rodriguez JA, Fresnadillo Martinez MJ. 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