• Pediatric Infection and Vaccine
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• v.12 no.2
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• pp.140-148
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• 2005

Purpose : To characterize the epidemiology and clinical features of invasive pneumococcal infections in Korean children. Methods : One hundred ninety four cases of invasive pneumococcal infections diagnosed at the Seoul National University Children's Hospital from October 1985 to December 2003 were analysed retrospectively. All isolates were screened for resistance to penicillin by oxacillin disc diffusion test. Serotypes were determined for 125 isolates. Results : The types of infection were bacteremia without focus 84/194(43%), meningitis 36/194(19%), pneumonia with bacteremia 36/194(19%), peritonitis 24/194(12%), other focal infections 3/194(2%). Fifty seven percent(110/194) of the episodes developed in the immunocompromised and 20%(37/194) were nosocomially acquired. The patients younger than 2 years of age was 60% in the immunocompetent patients and 25% in the immunocompromised patients. The overall case fatality rate was 7%. All the isolates by 1988 were susceptible to penicillin screened by oxacillin disk. Penicillin resistance was first detected in 1989(20%), and then increased rapidly; 89% in 1995, 69% in 1996, and 80~100% thereafter. The seven most frequently isolated serotypes were 23F, 19F, 14, 6B, 6A, 9V and 19A, which accounted for 70% of total isolates. Conclusion : S. pneumoniaeis an important cause of morbidity and mortality in children. Invasive infections caused by S. pneumoniae most often occurred in infants and young children, while they are frequent in older immunocompromised children as well. This is the largest case series on invasive pneumococcal infections in Korean children.

• Parasites, Hosts and Diseases
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• v.27 no.2
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• pp.101-108
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• 1989

This study was performed to observe the role of Pneumocystis carinii as an etiologic agent of interstitial pneumonia in immunocompromised hosts. Total 90 male Sprague-Dawley rats, approxi. mately 150-180 g, were used. Fifteen of them were used as control group and remaining 75 (5 groups) were as immunosuppression groups; group 1 received prednisolone (25 mg/kg twice weekly) only; group 2 Prednisolone and tetracycline (75 mk/kg/day) ; group 3 Prednisolone, tetracycline and trimethoprim-sulfamethoxasole (50~250 mg/kg/day) : group 4 prednisolone and trimethoprim-sulfamethoxasole; and group 5 prednisolone and griseofulvin (300 mg/kg/day) until death. The survival days of each group rat were calculated, and upon death their lungs were removed immediately and then stamp smears were prepared and stained by Giemsa or toluidine blue O. For histopathologic observation, lungs were fixed in 10% formalin, cut into sections and stained with Gomori's methenamine silvei, hematoxylin-rosin, and Brovkn & Brenn stain. The results obtained were as follows: 1. The mean survival time of each group rat was 19.3$\pm$5.2 days (group 1), 41.1$\pm$14.0 days (group 2), 50.5$\pm$18.4 days (group 3), 43.0$\pm$22.9 days (group 4) or 21.8$\pm$5.1 days (group 5). Significant differences were noted between group 1 and group 2(p<0.01), group 1 and group 3 (p<0.01), and group 1 and group 4 (p<0.01), which represented bacterial infections were most fatal in immunocompromised rats. Group 5 revealed no difference in the survival day from group 1, while significant differences were noted between group 2 and group 5(P<0.01), group 3 and group 5(p<0.01), and group 4 and group 5(p<0, 01), which represented little importance of fungal infection as the cause of death of the rats. 2. The first fatality due to p. carinii pneumonia occurred 17 days after the beginning of the immunosuppression. The occurrence rate of P. carinii pneumonia in the decreasing order was 92.9% (group 3), 80.0% (group 2 and group 5), 78.6% (group 4) and 33.3% (group 1). With regard to the pathological stage of P. carinii pneumonia, the stage 1 was 11.3%, the stage 2, 28.3%, and the stage 3, 60.4%. 3. Viewing from the duration of immunosuppression, bacterial pneumonia chieay appeared in 1 month, mixed infections (P. carinii and bacteria, or p. carinii and fungi) in 1~2 months, and pure P. carinii pneumonia after 2 months. The present study revealed that P. carinii pneumonia was the most important cause of death of immunocompromised rats later than 1 month after the start of immunosuppression.

• Pediatric Infection and Vaccine
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• v.18 no.1
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• pp.40-47
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• 2011

Purpose : Norovirus infection, a common cause of community-acquired gastroenteritis, can also lead to severe illness in immunocompromised patients. We investigated clinical manifestations of norovirus infection in pediatric cancer patients. Methods : Stool specimens were collected from pediatric patients with gastrointestinal symptoms between November 2008 and September 2009 at Samsung Medical Center, Seoul, Korea. Norovirus infection was identified by reverse-transcription polymerase chain reaction (RT-PCR). A retrospective chart review was performed in pediatric cancer patients who were diagnosed with norovirus infection. Results : Ten patients were diagnosed with norovirus infection by RT-PCR in stool samples. The median age was 0.83 years (range 0.25-5.5 years) and the male to female ratio was 1.5:1 (6 males and 4 females). Underlying diseases were hematologic malignancies (4/10, 40%), neuroblastoma (4/10, 40%), and brain tumors (2/10, 20%). Three patients were infected before hematopoietic cell transplantation (HCT) and four patients after HCT. All patients had diarrhea (10/10, 100%), with a median frequency of diarrhea of 8.5 times/day (range 4-22 times/day). Median virus shedding duration was 72.5 days (range 19-299 days). Four patients with pneumatosis intestinalis were conservatively treated with bowel rest and total parenteral nutrition. One patient with severe diarrhea and bloody stool had concomitant chronic gut graft-versus-host disease (GVHD). Norovirus infection-related mortality was not observed. Conclusion : Norovirus infection can cause significant clinical manifestations with prolonged viral shedding in immunocompromised patients. Norovirus should be considered in pediatric cancer patients with severe gastrointestinal symptoms.

• Tuberculosis and Respiratory Diseases
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• v.67 no.1
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• pp.32-36
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• 2009

We report a case of disseminated Mycobacterium intracellulare infection in a 31-year-old man who had been diagnosed as having dermatomyositis and systemic lupus erythematosus 3-years prior. The patient developed a left pleural effusion M. intracellulare was repeatedly isolated from the pleural fluid. After antimycobacterial treatment, the patient's pleural effusion resolved, but a left knee joint effusion developed newly and M. intracellulare was cultured from the joint fluid. At present, the patient has been taking antimycobacterial medication for 15 months but his left knee joint fluid remains positive for M. intracellulare. To our knowledge, this is the second reported case of disseminated NTM infection in a non-HIV infected patient in Korea.

• Tuberculosis and Respiratory Diseases
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• v.65 no.6
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• pp.537-540
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• 2008

There are few reports of the pleuropulmonary involvement of a non-typhi Salmonella infection in immunocompromised patients with AIDS, malignancy, collagen vascular diseases, extended use of corticosteroids, sickle cell disease, or diabetes. We report a case of a non-immunocompromised patient who presented with concomitant empyema and mediastinitis due to Salmonella without a comorbid disease. A 26-year-old male patient, with a history of pneumonia 5 years earlier and having lived abroad for several years, presented chronic cough and febrile sensation. Pneumonia, empyema and mediastinitis were noted in a chest CT scan and Salmonella enteritidis and ${\beta}-hemolytic$ streptococcus were identified from a culture of the pleural fluid. Initially, he was treated with cefepime, metronidazole and clarithromycin. He was cured clinically and radiographically after an 8 week treatment with antibiotics. In conclusion, this report suggests that S. enteritidis can cause empyema and mediastinitis, albeit rarely.

• Parasites, Hosts and Diseases
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• v.50 no.3
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• pp.199-205
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• 2012

Toxoplasmic encephalitis is caused by reactivation of bradyzoites to rapidly dividing tachyzoites of the apicomplexan parasite Toxoplasma gondii in immunocompromised hosts. Diagnosis of this life-threatening disease is problematic, because it is difficult to discriminate between these 2 stages. Toxoplasma PCR assays using gDNA as a template have been unable to discriminate between an increase or decrease in SAG1 and BAG1 expression between the active tachyzoite stage and the latent bradyzoite stage. In the present study, real-time RT-PCR assay was used to detect the expression of bradyzoite (BAG1)- and tachyzoite-specific genes (SAG1) during bradyzoite/tachyzoite stage conversion in mice infected with T. gondii Tehran strain after dexamethasone sodium phosphate (DXM) administration. The conversion reaction was observed in the lungs and brain tissues of experimental mice, indicated by SAG1 expression at day 6 after DXM administration, and continued until day 14. Bradyzoites were also detected in both organs throughout the study; however, it decreased at day 14 significantly. It is suggested that during the reactivation period, bradyzoites not only escape from the cysts and reinvade neighboring cells as tachyzoites, but also converted to new bradyzoites. In summary, the real-time RT-PCR assay provided a reliable, fast, and quantitative way of detecting T. gondii reactivation in an animal model. Thus, this method may be useful for diagnosing stage conversion in clinical specimens of immunocompromised patients (HIV or transplant patients) for early identification of tachyzoite-bradyzoite stage conversion.

• Clinical and Experimental Pediatrics
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• v.54 no.3
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• pp.117-122
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• 2011

Purpose: Natural history and consequences of the novel 2009 influenza A H1N1(2009 H1N1) infection in immunocompromised pediatric patients are not yet fully understood. In this study, we investigated the clinical features and outcomes of the 2009 H1N1 infection in pediatric patients with hematological and oncological diseases. Methods: We retrospectively reviewed the medical records of 528 patients who had hematological and oncological diseases and who were treated at 7 referral centers located in the Yeungnam region. Among the 528 patients, 27 with definite diagnosis of 2009 H1N1 infection were the subjects of this study. All patients were divided into the following 3 groups: patients who were receiving chemotherapy (group 1), patients who were immunosuppressed due to a nonmalignant hematological disease (group 2), and patients who were off chemotherapy and had undergone their last chemotherapy course within 2 years from the influenza A pandemic (group 3). Results: All 28 episodes of 2009 H1N1 infection were treated with the antiviral agent oseltamivir ($Tamiflu^{(R)}$), and 20 episodes were treated after hospitalization. Group 1 patients had higher frequencies of lower respiratory tract infection and longer durations of fever and hospitalization as compared to those in group 2. Ultimately, all episodes resolved completely with no complications. Conclusion: These results suggest that early antiviral therapy did not influence the morbidity or mortality of pediatric patients with hematological and oncological diseases in the Yeungnam region of Korea after the 2009 H1N1 infection. However, no definite conclusions can be drawn because of the small sample size.

• Clinical and Experimental Pediatrics
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• v.48 no.3
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• pp.235-250
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• 2005

Acute diarrhea is one of the most common diseases that are seen in pediatric patients. In the management of acute diarrhea, several differential diagnostic criteria should be considered based on clinical and/or laboratory findings. These criteria include : (1) normal variant stool versus diarrhea (2) infectious versus non-infectious condition and (3) bacterial versus non-bacterial etiology. The use of antibiotics should be considered to manage diarrhea caused by bacteria accompanying fever and bloody diarrhea in the following cases : (1) patients with serious clinical course, (2) under three months, (3) immunocompromised patients, (4) patients with nutritional deficiency and (5) patients presenting with moderate-to-severe dehydration. In patients presenting with the symptoms suspected to be bacterial origin, whose clinical course is not serious, antibiotic therapy is not necessary. These patients are easily manageable at OPD level. Moreover, except for some cases in which the use of antibiotics is inevitable, pediatric diarrhea can be managed by providing the suitable foods alone with no necessity of other specific drugs. Accordingly, it is crucial not so much to depend on the drugs as to provide appropriate foods including oral rehydration solution(ORS) with no further episodes of diarrhea. Special attention should be paid to the fact that younger pediatric patients will undergo nutritional deficiency unless acute diarrhea is properly managed.

• Tuberculosis and Respiratory Diseases
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• v.79 no.2
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• pp.74-84
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• 2016

Nontuberculous mycobacteria (NTM) are emerging pathogens that affect both immunocompromised and immunocompetent patients. The incidence and prevalence of NTM lung disease are increasing worldwide and rapidly becoming a major public health problem. For the diagnosis of NTM lung disease, patients suspected to have NTM lung disease are required to meet all clinical and microbiologic criteria. The development of molecular methods allows the characterization of new species and NTM identification at a subspecies level. Even after the identification of NTM species from respiratory specimens, clinicians should consider the clinical significance of such findings. Besides the limited options, treatment is lengthy and varies by species, and therefore a challenge. Treatment may be complicated by potential toxicity with discouraging outcomes. The decision to start treatment for NTM lung disease is not easy and requires careful individualized analysis of risks and benefits. Clinicians should be alert to those unique aspects of NTM lung disease concerning diagnosis with advanced molecular methods and treatment with limited options. Current recommendations and recent advances for diagnosis and treatment of NTM lung disease are summarized in this article.

• Tuberculosis and Respiratory Diseases
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• v.79 no.2
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• pp.101-103
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• 2016

Nocardia species are aerobic, gram-positive pathogens found worldwide in soil. Nocardia is considered an opportunistic pathogen, and its infection mostly occurs in immunocompromised patients. We report a case of Nocardia farcinica induced mediastinitis and pneumonia that occurred in a 64-year-old male patient who had no significant medical history except for hypertension. He visited another hospital with a complaint of dyspnea and left chest wall pain. The symptoms arose 7 days ago without any trauma and they worsened. A mediastinal mass was found on computed tomography scan. After being transferred to our hospital for further evaluation, he was diagnosed with mediastinitis and pneumonia. As N. farcinica was found to be the causative organism by 16S rRNA sequencing, proper antibiotic therapy including trimethoprim/sulfamethoxazole was initiated immediately. After this, the patient improved and he was discharged. If an infection has a disseminating course, nocardiosis cannot be excluded even in immunocompetent patients. Once the diagnosis is established, prompt antibiotic therapy should be performed based on the severity.