ZpdN, a Plasmid-Encoded Sigma Factor Homolog, Induces pBS32-Dependent Cell Death in Bacillus subtilis.

The ancestral Bacillus subtilis strain 3610 contains an 84-kb plasmid called pBS32 that was lost during domestication of commonly used laboratory derivatives. Here we demonstrate that pBS32, normally present at 1 or 2 copies per cell, increases in copy number nearly 100-fold when cells are treated with the DNA-damaging agent mitomycin C. Mitomycin C treatment also caused cell lysis dependent on pBS32-borne prophage genes. ZpdN, a sigma factor homolog encoded by pBS32, was required for the plasmid response to DNA damage, and artificial expression of ZpdN was sufficient to induce pBS32 hyperreplication and cell death. Plasmid DNA released by cell death was protected by the capsid protein ZpbH, suggesting that the plasmid was packaged into a phagelike particle. The putative particles were further indicated by CsCl sedimentation but were not observed by electron microscopy and were incapable of killing B. subtilis cells extracellularly. We hypothesize that pBS32-mediated cell death releases a phagelike particle that is defective and unstable. IMPORTANCE: Prophages are phage genomes stably integrated into the host bacterium's chromosome and less frequently are maintained as extrachromosomal plasmids. Here we report that the extrachromosomal plasmid pBS32 of Bacillus subtilis encodes a prophage that, when activated, kills the host. pBS32 also encodes both the sigma factor homolog ZpdN that is necessary and sufficient for prophage induction and the protein ComI, which is a potent inhibitor of DNA uptake by natural transformation. We provide evidence that the entire pBS32 sequence may be part of the prophage and thus that competence inhibition may be linked to lysogeny.

Robust Stoichiometry of FliW-CsrA Governs Flagellin Homeostasis and Cytoplasmic Organization in Bacillus subtilis.

Flagellin (Hag) is one of the most abundant proteins in Bacillus subtilis Here we show that each flagellar filament is assembled from ∼12,000 Hag monomers and that there is a cytoplasmic pool of Hag that is restricted to 5% of the total. Hag is thought to be restricted at the level of translation by a partner-switching mechanism involving FliW and the homodimeric RNA-binding protein CsrA (CsrAdimer). We further show that the mechanism of translation inhibition is hypersensitive due to a 1:1 ratio of Hag to FliW, a 1:1 inhibitory ratio of FliW to CsrAdimer, and a nearly 1:1 ratio of CsrAdimer to hag transcripts. Equimolarity of all components couples single-molecule detection of Hag export to compensatory translation and causes cytoplasmic Hag concentrations to oscillate around the level of FliW. We found that stoichiometry is ensured by genetic architecture, translational coupling, and the ability of CsrAdimer to restrict hag transcript accumulation. We further show that homeostasis prevents Hag hyperaccumulation that would otherwise cause severe defects in intracellular architecture, perhaps due to increased molecular crowding. We note that FliW-CsrA-mediated structural homeostasis has similarities to that seen with some toxin-antitoxin systems.IMPORTANCE The intracellular concentration of flagellar filament protein Hag is restricted by the Hag-FliW-CsrA system in B. subtilis Here we show that the Hag-FliW-CsrAdimer system functions at nearly 1:1:1 stoichiometry and that the system is both robust with respect to perturbation and hypersensitive to the Hag intracellular concentration. Moreover, restriction of cytoplasmic Hag levels is important for maintaining proper intracellular architecture, as artificial Hag hyperaccumulation led to generalized spatial defects and a high frequency of minicell production. The Hag-FliW-CsrA system is conserved in the deeper branches of bacterial phylogeny, and we note that the Hag-FliW-CsrA "homeostasis module" resembles a toxin-antitoxin system where, by analogy, CsrA is the "toxin," FliW is the "antitoxin," and Hag is the target.

Lipid chemotaxis and signal transduction in Myxococcus xanthus.

The lipid phosphatidylethanolamine (PE) is the first chemoattractant to be described for a surface-motile bacterium. In Myxococcus xanthus, the specific activity of PE is determined by its fatty acid components. Two active species have been identified: dilauroyl PE and dioleoyl PE. Excitation to dilauroyl PE requires fibril appendages and the presence of two cytoplasmic chemotaxis systems, of which one (Dif) appears to mediate excitation and the other (Frz) appears to mediate adaptation. A possible mechanism for fibril-mediated signal transduction is discussed, along with the potential roles for PE chemotaxis in the context of the M. xanthus life cycle.

Surgical therapy of obstructive sleep apnea in children with severe mental insufficiency.

Obstructive sleep apnea is the underlying cause of a variety of pediatric maladies, including pulmonary hypertension and failure to thrive. In children, unlike adults, obstruction secondary to lymphoid hyperplasia is often encountered; adenotonsillectomy restores airway patency. Patients who fail this procedure, such as children with cerebral palsy and associated muscular hypotonia, may face tracheotomies. We report on 10 pediatric patients with severe mental insufficiency and obstructive sleep apnea in whom palatal hypotonicity and lack of adenotonsillar hypertrophy was identified. Uvulopalatopharyngoplasty was performed in conjunction with adenotonsillectomy to enlarge the diameter of the nasopharyngeal inlet with successful resolution of the obstructive symptoms in eight patients. The remaining two children required more surgery. This procedure is presented as a possible alternative to tracheotomy in selected patients.

Fourth branchial pouch sinus: principles of diagnosis and management.

The fourth branchial pouch sinus is a congenital anomaly which most frequently manifests itself by recurrent episodes of neck abscess or acute suppurative thyroiditis. This lesion usually becomes symptomatic before the age of 10 years and is more common than has previously been suspected. It has been found on the left side in 93% of the 28 cases reported in the English literature. Barium swallow during periods of quiescence and nasopharyngoscopy have frequently been successful in identifying the presence of these embryological remnants. Definitive therapy consists of total excision of the sinus tract, which can be facilitated by direct endoscopic placement of a Fogarty catheter into the sinus lumen before surgical exploration. The embryological basis for the occurrence of these sinuses is discussed.

Cervicofacial mycobacterial adenitis in children: endemic to San Diego?

Nontuberculous mycobacteria (NTM) are an important cause of cervicofacial lymphadenitis in children. A dramatic increase has been seen in confirmed cases of NTM lymphadenitis in San Diego in the past few years. This report encompasses a span of 2 years 9 months, during which 22 children had confirmed NTM infection and another 14 had necrotizing granulomatous lymphadenitis in whom the specific diagnosis of NTM could not be made. This apparent increase in the prevalence of NTM as compared to previous reports in the literature suggests a possible endemic risk for NTM in the San Diego area. These cases are reviewed and our diagnostic and surgical approach to possible NTM infection is described. We also discuss possible explanations for the increasing occurrence of NTM in the San Diego area.

One-stage laryngotracheoplasty.

This article documents the evolution of our approach to the repair of subglottic stenosis in infants. With increasing experience in the management of subglottic stenosis using the anterior cricoid split procedure, we extended our procedure to include older children. This then led to the use of the one-stage procedure for repair of severe and mature subglottic stenosis. We present the results of surgical repair in 13 patients. Extubation was accomplished in 12 of 13 patients using one-stage laryngotracheoplasty.

Split calvarium cranioplasty.

Fronto-orbital deformities secondary to trauma, infection, or surgery create a difficult problem for the reconstructive surgeon. The location of the deformity is particularly critical because it involves the most visible part of the face. Since the skull is rarely able to produce bony regeneration over large areas, numerous alloplastic materials have been used to repair these defects. Complications with these materials are commonplace. Autogenous bone has been used with good results and avoids many of the problems inherent to the use of foreign materials. Rib, scapula, and iliac crest may be used, but they require a separate incision and often provide less than satisfactory cosmetic results. We describe a technique of cranioplasty utilizing split calvarium for repair of frontal bone defects. Cosmesis is excellent, morbidity is minimal, and only one incision is necessary.

Respiratory distress in the neonate. Sequela of a congenital dacryocystocele.

Congenital dacryocystoceles presenting with intranasal extension may precipitate respiratory distress in neonates. Twenty-one children have been described as having congenital dacryocystoceles with intranasal extension, and, of these, 14 had respiratory distress. We present a series of patients with congenital dacryocystoceles who presented with ranging degrees of respiratory distress. Magnetic resonance imaging and computed tomographic scans confirmed the diagnosis. In all cases, the endonasal portion of the cyst was marsupialized endoscopically with complete resolution of symptoms. Pertinent embryology, anatomy, clinical presentation, and treatment are discussed.

Tracheal stenosis in Larsen's syndrome.

Larsen's syndrome is known to have an association with laryngomalacia and tracheomalacia. We report a case of Larsen's syndrome with respiratory difficulty due to a tracheal stenosis. To our knowledge, this association has not previously been reported.

Neonatal otitis media. An update.

Neonatal otitis media may be an isolated infection or part of a more complex sepsis syndrome. Because early studies suggested that the microbiologic characteristics of neonatal otitis media included a high risk of gram-negative coliforms and Staphylococcus aureus, tympanocentesis was recommended routinely. Subsequent studies have supported empiric medical therapy in selected patients, reserving tympanocentesis for patients in whom medical treatment fails. Because of these conflicting recommendations, records from 37 neonates with otitis media who underwent tympanocentesis from 1986 through 1991 were studied retrospectively. Cultures in one outpatient (11%) and four inpatients (13%) yielded Escherichia coli, all of which were sensitive to amoxicillin. No cultures of S aureus were identified. Sterile cultures and pneumococcus isolates were found most frequently. No septic or intracranial complications were noted. All patients were discharged on regimens of routine antibiotics for otitis media.

The prognostic value of endotracheal tube-air leak following tracheal surgery in children.

In an effort to determine if the endotracheal tube-leak pressure has prognostic value in relation to a successful outcome after one-stage laryngotracheal reconstruction or cricoid split surgery, a retrospective analysis was performed on 17 children who had undergone such surgery. The daily leak pressures, length of intubation, and ultimate outcome of attempts at extubation were noted. One hundred percent of patients with a leak pressure of less than 20 cm H2O on the day before extubation were successfully extubated. In contrast, the failure rate was 100% in children extubated with a leak of greater than 30 mm H2O. The difference between these two groups was statistically significant (chi 2, 13.03). Sixty percent of patients with leak pressures in the range of 21 to 30 cm H2O were successfully extubated. The endotracheal tube-leak pressure is a parameter that has prognostic value, and should be considered in determining when to extubate children who have undergone tracheal reconstructive surgery.

Actinomycosis in obstructive tonsillar hypertrophy and recurrent tonsillitis.

A quantitative analysis of adenoid and tonsillar specimens from 460 patients was performed. The patients underwent tonsillectomy or adenotonsillectomy for either recurrent tonsillitis or obstructive tonsillar hypertrophy. Histologic preparations revealed Actinomycetes as statistically more prevalent in the obstructive population. The presence of Actinomycetes in the adenotonsillar core of this diagnostic group may indicate an etiologic role for this organism in tonsillar and adenoidal hypertrophy.

Skull metastases from follicular thyroid carcinoma.

Distant metastatic disease from thyroid carcinoma is becoming a rare problem. Physicians and the public are increasingly aware of minimally invasive methods of early diagnosis of thyroid malignancy, such as fine-needle aspiration with cytologic examination. Total thyroidectomy itself has become less associated with morbidity than it once was. We describe three patients with follicular thyroid carcinoma metastatic to the skull who were seen recently. Two of these patients had masses neglected for 20 and 50 years, respectively. The management of this disease entity is discussed.

Clinical update on 10 children treated with intralesional cidofovir injections for severe recurrent respiratory papillomatosis.

OBJECTIVES: To continue assessment of the benefits and risks of intralesional administration of cidofovir, an acyclic nucleoside phosphonate, for treating severe recurrent respiratory papillomatosis (RRP) in pediatric patients, and to discuss guidelines for larger prospective multi-institutional studies of the use of cidofovir. DESIGN: Prospective case series. SETTING: Tertiary care children's hospital. PATIENTS: A total of 10 patients with severe RRP (defined as requiring debulking procedures to maintain airway patency at least once a month) underwent intralesional cidofovir therapy. The original 5 patients have received more than 1 year of follow-up since their last cidofovir injection, and 5 subsequent patients have been treated with a revised injection protocol. INTERVENTION: Microsuspension laryngoscopy with intralesional injection of cidofovir after repetitive carbon dioxide laser treatments and mechanical debulking of papillomas. MAIN OUTCOME MEASURES: Papilloma stage at the time of serial laryngoscopies. Histologic examination of biopsy specimens of laryngeal tissue obtained 1 year or more after last cidofovir injection. RESULTS: There was evidence of marked improvement in the 4 of the 5 new patients enrolled under the revised injection protocol, continuation of a disease-free state in 1 of the original 5 patients, and sustained improvement in 4 of the 5 original patients, resulting in a significantly reduced interval of intervention. CONCLUSIONS: Intralesional cidofovir therapy continues to show benefit in the treatment of severe RRP in pediatric patients. Safety profiles have not been fully established, but current histologic data are reassuring.

Intralesional cidofovir for recurrent respiratory papillomatosis in children.

OBJECTIVE: To assess the potential benefit of intralesional administration of cidofovir, an acyclic nucleoside phosphonate with activity against several DNA viruses, for treating severe respiratory papillomas in pediatric patients. DESIGN: Prospective case series. SETTING: Tertiary care children's hospitals. PATIENTS: Five pediatric patients with severe recurrent respiratory papillomatosis requiring laryngoscopy with carbon dioxide laser therapy more frequently than once a month to maintain airway patency. Each patient underwent between 12 and 33 laryngoscopies with laser treatment prior to being injected with cidofovir. INTERVENTION: Microsuspension laryngoscopy with intralesional injection of cidofovir (Vistide) in conjunction with mechanical debulking and carbon dioxide laser of papillomas. MAIN OUTCOME MEASURE: Papilloma stage at time of serial laryngoscopies. RESULTS: One patient was disease free and 3 patients demonstrated a dramatic response to adjuvant therapy with cidofovir at the 9-month follow-up visit after the last injection of cidofovir. One patient showed an improvement in papilloma stage that was possibly related to concurrent therapy with interferon. CONCLUSIONS: Intralesional injection of cidofovir seems to be of benefit in the treatment of severe respiratory papillomatosis in pediatric patients. Larger prospective studies with longer follow-up will be required before cidofovir can be considered an accepted means of managing this difficult disease.

Coccidioides immitis subperiosteal abscess of the temporal bone in a child.

A destructive granulomatous lesion of the temporal bone caused by Coccidioides immitis disseminated from a pulmonary lesion was found in a 4-year-old immunocompetent child. To our knowledge, it is the first case of coccidioidomycosis of the temporal bone reported in the world literature. The child presented with pain in her right ear and a 6-month history of intermittent fever, which partially responded to multiple courses of antibiotics. A tender erythematous postauricular swelling consistent with a subperiosteal abscess subsequently developed over 1 month. A mastoidectomy showed granulation tissue with pockets of purulence, and histologic evaluation of the specimen revealed spherules of C immitis, later verified by culture. The patient responded to intravenous amphotericin B therapy, without evidence of disease recurrence. Coccidioides immitis is endemic in regions of the Southwestern United States, with extremely infectious characteristics and relative resistance to medical therapy. Coccidioidomycosis should be considered in the differential diagnosis of a granulomatous lesion of the temporal bone.

The otolaryngologic manifestations of Pelizaeus-Merzbacher disease.

Pelizaeus-Merzbacher disease is a condition of central nervous system dysmyelination. We describe a familial series in which both otologic and laryngologic abnormalities were present. The diagnosis of this invariably fatal disorder can be made on a clinical and/or pathologic basis. As the otolaryngologic manifestations are often the first to appear, the consulting head and neck surgeon may be essential in the initial diagnosis of this hereditary disease.

Acute coalescent mastoiditis in an infant: an emerging trend?

There is some evidence to suggest that the incidence and complications of ACM may be increasing. However, in the current era of widespread access to health care and broad-spectrum antibiotics, an intratemporal or intracranial complication from acute otitis media may not initially be suspected. The reported case is significant in that the patient was very young, had no underlying disease or immunocompromise, and did not have a known antecedent acute otitis media. With the emergence of resistant streptococcal species and prolonged survival in immunocompromised patients, the relative incidence of complications caused by acute otitis media will probably continue to rise, making it imperative that we raise our index of suspicion for previously rare infectious complications of relatively common diseases.

Pediatric airway manifestations of gastroesophageal reflux.

Gastroesophageal reflux (GER) in children may be classified as physiologic or pathologic, depending on its degree and consequences. There are many head and neck complications of GER in pediatric patients, but most numerous are the airway manifestations, including stridor, recurrent croup, exacerbation of subglottic stenosis, laryngeal irritation with or without laryngospasm, chronic cough, and obstructive apnea. Diagnosis may be difficult unless there is a high index of suspicion for GER and awareness of the concept of "silent" GER. We present the common pediatric airway manifestations of GER, illustrated by case reports, and provide a paradigm to assist in the diagnosis and management of children with airway compromise associated with GER.