Yukiyoshi Hyo

Role of Ciprofloxacin in Its Synergistic Effect with Fosfomycin on Drug-Resistant Strains of Pseudomonas aeruginosa

Background: The aim of this study was to investigate the synergistic effect of ciprofloxacin (CPFX) and fosfomycin (FOM) on CPFX-resistant Pseudomonas aeruginosa strains. Methods: The synergistic effect was evaluated using the fractional inhibitory concentration index, acute bactericidal effect and morphological observation. Results: In the fractional inhibitory concentration index experiments, the combination of CPFX with FOM showed a synergistic effect in 20 of 74 (27.0%) strains of P. aeruginosa. From the morphological observations, it was determined that CPFX affected the outer membrane structure. CPFX combined with FOM caused striking morphological changes, resulting in bacteriolysis. A time lag experiment suggested that the addition of CPFX prior to FOM produced more pronounced bactericidal activity than the addition of FOM prior to CPFX. Conclusions: These results indicate that the combination of CPFX with FOM induces a synergistic effect on CPFX-resistant P. aeruginosa strains. The role of CPFX is thought to be related to damage of the outer membrane, enhancing FOM penetration.

Stapediovestibular dislocation with pneumolabyrinth.

Traumatic luxation of the stapes into the vestibule is a rare entity, and the disease complicated with pneumolabyrinth is extremely rare. We report the case of a 72-year-old woman with pneumolabyrinth associated with a stapediovestibular dislocation. The patient presented with vertigo and nystagmus following penetrating trauma to the middle ear. High resolution computed tomography scans demonstrated air in the vestibule and dislocation of the stapes. Exploratory tympanotomy demonstrated oozing of the perilymph from the oval window and depression of the stapes into the vestibule. Pneumolabyrinth and stapes luxation detected by high resolution computed tomography should be predictive of a perilymphatic fistula.

Thickening of the cell wall in macrolide-resistant Staphylococcus aureus

Macrolides are widely used at low dosage for long-term therapy of chronic sinusitis. Twenty clinical macrolide-resistant Staphylococcus aureus strains were morphologically compared with 10 clinical macrolide-sensitive strains. PCR amplification was performed to determine the presence of four known macrolide resistance genes. Transmission electron microscopy revealed significantly thicker cell walls in clinical macrolide-resistant strains. Even though the ultrastructural characteristics were shared by all macrolide-resistant strains, they were not associated with the presence or absence of the known macrolide-resistance genes. We also demonstrated that macrolide-resistant mutant strains derived in vitro from a macrolide-sensitive parent strain had thickened cell walls and did not harbor the known macrolide-resistance genes. These results, therefore, revealed that macrolide-resistant S. aureus strains have thickened cell walls as a common ultrastructural characteristic and that cell wall thickening is likely mediated by an unknown gene which is unrelated to any known macrolide resistance gene.

Antimicrobial effects of Burow's solution on Staphylococcus aureus and Pseudomonas aeruginosa

Burow’s solution has been shown to be effective against chronic suppurative otitis media and otitis externa. We demonstrated that Burow’s solution had antibacterial effects against Staphylococcus aureus and Pseudomonas aeruginosa, inducing ultrastructural changes in these bacteria in vitro. S. aureus strain 209P and P. aeruginosa strain IID1130 were treated with 13% Burow’s solution. Viable cell counts were determined to measure bactericidal effects. Ultrastructural changes in cells of both strains were examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Viable cell counting revealed that S. aureus cells treated with Burow’s solution were killed within 30 min. The viable cell count of P. aeruginosa was reduced by 1 × 107 colony-forming units/ml (CFU/ml) after a 60-min treatment. SEM examination of S. aureus revealed blebbing on the surface of bacterial cells, whereas TEM revealed undulating deformation of the bacterial cell wall, diluted cytoplasm, and cell membrane detachment. SEM observations of P. aeruginosa revealed a more apparent undulating deformation of the bacterial cell surface. TEM observations also revealed deformations in the bacterial cell wall and diluted cytoplasm in both bacteria. These findings show that Burow’s solution is active against S. aureus and P. aeruginosa, resulting in damage to the cell wall.

Characteristic cell wall ultrastructure of a macrolide-resistant Staphylococcus capitis strain isolated from a patient with chronic sinusitis

Fourteen-membered-ring macrolides have an antiinflammatory effect, in addition to their antibacterial effect, and are widely used at low dosages for long-term therapy for chronic inflammatory disease such as diffuse pan-bronchiolitis and chronic sinusitis. A macrolide-resistant coagulase-negative staphylococcal strain was obtained from the maxillary sinus of a patient with chronic sinusitis, who failed long-term macrolide therapy. The isolated strain was characterized as Staphylococcus capitis and had an MIC for erythromycin greater than 128 μg/ml. Morphological observation demonstrated that this macrolide-resistant S. capitis strain had a thicker cell wall than macrolide-sensitive S. capitis strains. Moreover, the strain was not carrying any other than the four genes that are known mainly to encode for macrolide resistance in S. aureus. Therefore, the strain had an unknown macrolide-resistance mechanism that might be related to cell wall thickening.

Neck swelling from a retropharyngeal abscess caused by penicillin-resistant Streptococcus pneumoniae: a case report.

BackgroundIn small children, retropharyngeal abscesses usually occur after upper respiratory tract infections. Unlike in adults, these abscesses are difficult to diagnose in small children, and can rapidly develop into deep neck or mediastinal abscesses.Case presentationA 2-year-old Japanese boy recently presented to our department with a chief complaint of neck swelling. Physical examination revealed bilateral tonsillitis and swelling of the left posterior pharyngeal wall. Emergency neck computed tomography angiography showed a contrast-enhanced abscess cavity posterior to the left retropharyngeal space, and a low-density area surrounded by an area without contrast enhancement in the posterior neck. The latter was suspected to be a deep neck infection secondary to a retropharyngeal abscess. After surgery, the patient was diagnosed with a retropharyngeal abscess and concurrent cystic lymphangioma. The lesions improved after intraoral incision and drainage, and administration of antibiotics.ConclusionLymphangiomas and retropharyngeal abscesses are both known to be more common in children than in adults. However, we found no other reports of concomitant presentation of lymphangioma and retropharyngeal abscess in the literature.

Nasal septal abscess caused by anaerobic bacteria of oral flora

Although nasal septal abscess (NSA) was formerly common, it has become rare since the development of antibiotics. NSA, if left untreated, can lead to intracranial complications such as meningitis and eventually result in saddle-nose deformity. NSA often occurs after injury, and indigenous skin bacteria such as Staphylococcus aureus are frequently detected. We treated a patient who had injured the upper alveolus in a fall on the stairs and developed NSA two weeks later. Anaerobic bacteria, including Veillonella parvula and Peptostreptococcus sp., were detected. Symptoms were relieved by needle and incisional drainage. Our patient represents a very rare case of NSA in terms of the cause of onset and the detected bacteria. Early drainage can result in good outcomes.

Two cases of thermal burns of the larynx in older men

Cases of thermal burns of the larynx in infants and in patients with mental illness have been reported, but those in older people are rare. We report two cases of thermal burns of the larynx in older people caused by ingestion of microwave-heated food (meat and potato stew or a bean-jam filled bun). Both patients were users of full dentures. Conservative therapy was effective in one patient, while tracheotomy was performed in the other patient at the time of the initial examination. Hot food is expelled from the mouth as a reflective response, preventing thermal burns of the larynx. However, in older individuals, sense perception is impaired and reflexes are slowed. Further, the oral mucosa is protected if full dentures are placed. Therefore, heat is likely to not be perceived and reflexes occur only after the food has reached the larynx, thereby causing thermal burns of the larynx. The number of such cases may increase as the number of older patients rises in the current aging society. Therefore, raising awareness of such cases is important.

Iliopsoas Abscess Possibly due to Klebsiella pneumoniae Infection after Chemoradiotherapy for Hypopharyngeal Cancer

Iliopsoas abscess was once an uncommon condition but now occurs somewhat more frequently due to the increasing number of immunocompromised patients, such as those with diabetes. We encountered a case of iliopsoas abscess following chemoradiotherapy for hypopharyngeal cancer. A 60-year-old man was admitted for a sore throat and left neck swelling. Hypopharyngeal cancer was diagnosed, but the patient refused surgery. After two rounds of chemotherapy, febrile neutropenia developed and chest computed tomography (CT) revealed an iliopsoas abscess. The platelet count was low but recovered after administration of antibiotics and could not be explained by puncture of the abscess. CT-guided drainage eventually improved his symptoms. Even for disorders of the head and neck region, iliopsoas abscess should be suspected in immunocompromised patients who develop a fever. CT and magnetic resonance imaging should be performed at an early stage as it is important to determine whether surgical drainage is indicated.