• Pediatric Infection and Vaccine
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• v.18 no.1
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• pp.23-30
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• 2011

Purpose : Acinetobacter baumannii is an aerobic, gram negative coccobacillus. Due to its pathogenicity and ability to accumulate diverse mechanisms of resistance, the importance of this organism is increasing. Many reports have targeted adults, and studies of pediatric patients are limited. This study aims to investigate the current status of A. baumannii infection in children. Methods : From January 2001 to December 2008, 505 patients hospitalized with A. baumannii infection were enrolled. Admission records for underlying disease, duration of hospitalization, previous antibiotic use, location of admission, presence of ventilator care, and resistance to antibiotics were retrospectively reviewed and analyzed. Results : Hemato-oncological disease and neurological disease were 30.6% and 24.3% of all cases; therefore, these were the most common underlying diseases of patients with A. baumannii infection. Prevalence of A. baumannii infection was 78.1% in patients with previous antibiotic use, which was higher than that of the group not using previous antibiotic. And prevalence of multi-drug resistant and pan-drug resistant A. baumannii infection was 76.4% and 38.3% in patients with ICU care, 76.8% and 38.9% with ventilator care, and these were higher than the others. Rate of resistance to all groups of antibiotics showed a gradual increase to over 50% in 2008. Multi-drug resistant A. baumannii was 63.5% and pan-drug resistant A. baumannii was 48.2% of all cases. Conclusion : Prevalence of A. baumannii infection and resistance to antibacterial agents of A. baumannii is increasing. Adequate use of antibiotics and infection control should be emphasized in pediatric patients.

• Clinical and Experimental Pediatrics
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• v.49 no.8
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• pp.882-888
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• 2006

Purpose : Bacteremia is one of the major concerns in the treatment of pediatric cancer patients. This study was to determine the etiologic agents and the pattern of antibiotic susceptibilities in a single tertiary medical center. Methods : We retrospectively reviewed the medical records of the cases of bacteremia in pediatric cancer patients from 1998 to 2005 in Keimyung University Dongsan Medical Center. Results : There were 62 cases of bacteremia from 44 patients. Gram-positive organisms(48.3%) were more common than gram-negative organisms(38.7%) or fungi(13%). Among gram-positive organisms, Staphylococcus epidermidis was the most common etiologic agent(63.3%), followed by Staphylococcus aureus(16.7%), ${\alpha}$-hemolytic Streptococcus(16.7%), and Streptococcus mitis(3.3%). Among gram-negative organisms, Alcaligenes xylosoxidans was the most common agent(41.7%) and the other organisms were Klebsiella pneumoniae(20.8%), Stenotrophomonas maltophilia(12.5%), Acinetobacter baumanii(8.2%), etc. In febrile neutropenic patients, however, K. pneumoniae was the most common cause of gram-negative bacteremia. All of the isolated K. pneumoniae in our center produced extended-spectrum beta-lactamase and were related with high mortality. S. aureus, S. epidermidis, and Streptococcus species were all susceptible to vancomycin and teicoplanin. Most staphylococci were resistant to penicillin and oxacillin. Most of the gram-negative organisms were susceptible to imipenem. Conclusion : Gram-positive organisms were more commonly isolated than gram-negative organisms in pediatric cancer patients like other studies. We could obtained valuable information on the choice of proper antibiotics in our institution. Further studies will be needed to explain the prevalence of A. xylosoxidans in our center.

• Pediatric Infection and Vaccine
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• v.12 no.1
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• pp.67-74
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• 2005

Purpose : The incidence of mortality associated with respiratory difficulties is decreasing nowadays contributed to the development of neonatology. However, complications associated with mechanical ventilator are increasing. This study is to determine clinical manifestations, diagnositc availability of the endotracheal tip culture in patients with Ventilator-Associated Pneumonia(VAP) in neonatal intensive care unit(NICU). Methods : A retrospective analysis of 50 neonates who were admitted to the NICU of Kangnam Sacred Heart Hospital and had given mechanical ventilator from 1 January 2000 to 30 June 2003. VAP group defined as neonates who had pneumonia with mechanical ventilation longer than 48 hours. They were classified into VAP group(n=13) and control group (n=37) and the prevalence, microorganisms cultured from the endotracheal tube tip and risk factors were investigated. Results : The prevalence of VAP was 26.0%(n=13) and the most dominant microorganism cultured in our NICU was methicillin-resistant coagulase negative staphylococcus(MR-CNS) in 4 cases. Other microorganisms were Pseudomonas, Enterobacter, methicillin-resistant Staphylococcus aureus(MRSA) and Klebsiella. Gestational age, birth weight, Apgar score, respiratory distress syndrome, retinopathy of prematurity, bronchopulmonary dysplasia, sepsis, renal failure, pulmonary hemorrhage, pneumothorax were not different significantly between two groups except intraventricular hemorrhage(P<0.001) and patent ductus arteriosus(P<0.05). Duration of hospital stay and mortality rate were also not different significantly. Conclusion : VAP occurred at a significant rate among mechanically ventilated NICU patients. Despite of limitation of encotracheal tip culture, the most common microorganism was MR-CNS. We should be aware of occurrence of VAP in NICU neonate who were with mechanical ventilator and should treat with great care.

• Tuberculosis and Respiratory Diseases
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• v.64 no.1
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• pp.8-14
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• 2008

Background: Acinetobacter infections are difficult to treat as they often exhibit multiple resistance to the antibiotics that are currently available for the treatment of pneumonia. Colistin is active against gram-negative bacteria, including the multiple drug resistant (MDR) Acinetobacter species. However, intravenous administration of colistin was abandoned because of its nephrotoxicity and neurotoxicity. The aims of this study were to examine the efficacy and safety of colistin administered by aerosol in the treatment of pneumonia caused by MDR Acinetobacter baumannii. Methods: We retrospectively reviewed the medical records of patients admitted to the intensive care unit (ICU) from Dec. 2006 to Aug. 2007 who had been diagnosed as suffering from pneumonia due to MDR Acinetobacter baumannii and had been treated with nebulized colistin. Results: 31 patients received aerosolized colistin. The average duration of the treatment was $14{\pm}7$ days and the daily dose of ranged from 225 mg to 300 mg. All patients received concomitant intravenous antimicrobial agents. The average length of the stay in the ICU was $34{\pm}21$ days and in the hospital $58{\pm}52$ days. The overall microbiological eradication was observed in 25 patients (80.6%). 14 of these (56%) were cured, and 11 (44%) were infected with other microorganisms. The overall crude mortality of the ICU was 48%. Nephrotoxicity and significant bronchial constriction did not occur in any patient during neublized colistin treatment. Conclusion: Nebulized colistin may be a safe and effective option in the treatment of pneumonia due to MDR Acinetobacter baumannii. Its role in therapy warrants further investigation in comparative studies.

• Pediatric Infection and Vaccine
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• v.9 no.2
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• pp.163-174
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• 2002

Background : To delineate the changes in the causative agents of neonatal sepsis and their antimicrobial susceptibilities in the neonatal intensive care unit and nursery of Hanyang University Hospital during the past 10 years. Methods : Hospital records of 15,144 patients hospitalized at the NICU and nursery of Hanyang University Hospital from 1989 to 1998 were reviewed and neonates diagnosed of neonatal sepsis were sorted and included in the study. The study period was divided into Period A(the first 5 years) and Period B(the second 5 years) to analyse causative agents and their antimicrobial susceptibilities. Results : Neonatal sepsis was diagnosed in 170 patients(1.1%{Period A 1.2%, Period B 1.0%}) among the total of 15,144 inpatients. Two hundred isolates(Period A 109 isolates, Period B 91 isolates) were identified in 186 blood cultures(Period A 99 cultures, Period B 87 cultures) from 170 patients(Period A 91 patients, Period B 79 patients). The average age at the onset of the disease, when the initial blood culture was drawn, was 12.3 days old(Period A 8.8 days, Period B 16.3 days), and the proportion of the early onset disease was 34.7% in Period A and 23.0% in Period B, indicating that neonatal sepsis developed earlier during Period A. Among the isolated organisms including Gram positive bacteria[132(66.0%)], Gram negative bacteria [60(30.0%)], and fungi[8(4.0%)], coagulase negative Staphylococcus(CNS) was the most common organism(69/34.5%), followed by Staphylococcus aureus(36/18.0%), Klebsiella pneumoniae(17/8.5%), Enterococcus(12/6.0%), Enterobacter cloacae(8/4.0%), Escherichia coli(6/3.0%), and Pseudomonas aeruginosae(5/2.5%). The isolated fungi were Candida parapsilosis, Candida albicans, and Trichosporon pullulans. CNS, S. aureus and Acinetobacter baumannii were isolated more frequently in Period A compared to Period B. Antimicrobial susceptibilities of CNS and S. aureus to methicillin and the first generation cephalo sporins were decreased in Period B compare to Period A, those to aminoglycosides were increased in Period B, and vancomycin resistant strains were not identified. K. pneumoniae, Enterococcus, E. coli, and P. aeruginosa were isolated less frequently in Period B, compared to Period A. For K. pneumoniae, antimicrobial susceptibilities to the first generation cephalosporins were low in both Periods A and B, those to tobramycin and gentamicin were increased in Period B, and those to amikacin, ceftriaxone, and trimethoprim-sulfamethoxazole were high in both Periods A and B. Antimicrobial susceptibilities of Enterococcous to ampicillin, penicillin, and the first generation cephalosporins were decreased in Period B, but vancomycin resistant strains were not identified. Conclusion : The occurrence rate of neonatal sepsis during the past 10 years in the NICU and nursery of the Hanyang University hospital was 1.1%, and the most common causitive agents were CNS and S. aureus, to which the antimicrobial susceptibilities to the first line drugs decreased in the later half of the study period with no vancomycin resistant isolates identified. Group B Streptococcus known to be the most common agent causing neonatal sepsis was not identified, and K. pneumoniae was isolated more commonly during the later half of the study period without decreased antimicrobial susceptibilities.