• Journal of Microbiology and Biotechnology
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• v.27 no.7
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• pp.1249-1256
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• 2017

In our search for new sources of bioactive secondary metabolites from Streptomyces sp., the ethyl acetate extracts from endophytic Streptomyces SUK 25 afforded five active diketopiperazine (DKP) compounds. The aim of this study was to characterize the bioactive compounds isolated from endophytic Streptomyces SUK 25 and evaluate their bioactivity against multiple drug resistance (MDR) bacteria such as Enterococcus raffinosus, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumanii, Pseudomonas aeruginosa, and Enterobacter spp., and their cytotoxic activities against the human hepatoma (HepaRG) cell line. The production of secondary metabolites by this strain was optimized through Thornton's medium. Isolation, purification, and identification of the bioactive compounds were carried out using high-performance liquid chromatography, high-resolution mass liquid chromatography-mass spectrometry, Fourier transform infrared spectroscopy, and nuclear magnetic resonance, and cryopreserved HepaRG cells were selected to test the cytotoxicity. The results showed that endophytic Streptomyces SUK 25 produces four active DKP compounds and an acetamide derivative, which were elucidated as $cyclo-({\text\tiny{L}}-Val-{\text\tiny{L}}-Pro)$, $cyclo-({\text\tiny{L}}-Leu-{\text\tiny{L}}-Pro)$, $cyclo-({\text\tiny{L}}-Phe-{\text\tiny{L}}-Pro)$, $cyclo-({\text\tiny{L}}-Val-{\text\tiny{L}}-Phe)$, and N-(7-hydroxy-6-methyl-octyl)-acetamide. These active compounds exhibited activity against methicillin-resistant S. aureus ATCC 43300 and Enterococcus raffinosus, with low toxicity against human hepatoma HepaRG cells. Endophytic Streptomyces SUK 25 has the ability to produce DKP derivatives biologically active against some MDR bacteria with relatively low toxicity against HepaRG cells line.

• Journal of Microbiology
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• v.43 no.3
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• pp.257-259
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• 2005

Although automated continuous-monitoring blood culture systems are both rapid and sensitive, false-positive and false-negative results still occur. The objective of this study, then, was to evaluate negative results occurring with BacT/Alert 3D blood culture systems. A total of 1032 samples were cultured with the BacT/Alert 3D automated blood culture system, using both aerobic (BPA) and anaerobic (BPN) media, and 128 of these samples yielded positive results. A total of 904 negative blood samples were then subcultured in $5\%$ sheep blood agar, eosin methylene blue, chocolate agar, and sabouraud-dextrose agar. Organisms growing on these subcultures were subsequently identified using both Vitek32 (bioMerieux, Durham, NC) and conventional methods. Twenty four $(2.6\%)$ of the 904 subcultures grew on the subculture media. The majority $(83.3\%)$ of these were determined to be gram-positive microorganisms. Fourteen $(58.3\%)$ were coagulase-negative staphylococci, two $(8.3\%)$ were Bacillus spp., one $(4.2\%)$ was Staphylococcus aureus, and one $(4.2\%)$ was identified as Enterococcus faecium. Streptococcus pneumoniae and Neisseria spp. were isolated together in two $(8.3\%)$ vials. Gram-negative microorganisms comprised $12.5\%$ of the subcultures, of which two $(8.3\%)$ were found to be Pseudomonas aeruginosa, and one $(4.2\%)$ was Pseudomonas fluorescens. The other isolate $(4.2\%)$ was identified as Candida albicans. We conclude that the subculture of negative results is valuable in the BacT/Alert 3D system, especially in situations in which only one set of blood cultures is taken.

• Microbiology and Biotechnology Letters
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• v.50 no.1
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• pp.147-156
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• 2022

Urinary tract infections (UTIs) are one of the most common infections in different age groups, including children. Bacteria are the main etiological agents of UTIs. The aim of the present study was to isolate, identify, and determine the antibiotic susceptibility of bacteria isolated from children with UTIs from Baghdad, Iraq. Three hundred and two urine samples were collected from children aged 6 months to 12 years. The samples were cultured on blood agar and MacConkey agar. The selected colonies were subjected to biochemical tests and antibiotic susceptibility analysis using the Vitek^® 2 Compact automated microbial identification system. In this sample, 299 bacteria were identified, of which, 267 were gram-negative bacteria, and 32 were gram-positive bacteria. Escherichia coli (56%) was the most commonly isolated gram-negative bacteria, followed by Pseudomonas aeruginosa (14%), Enterobacter spp. (10.48%), Klebsiella pneumoniae (9.36%), Proteus spp. (7.8%), Acinetobacter baumannii (1.5%), and Morganella morganii (0.37%). Enterococcus faecalis (62.5%) was the most commonly detected gram-positive bacteria, followed by Staphylococcus aureus (37.5%). E. coli and P. aeruginosa were the most antibiotic-resistant bacteria. Among the tested antibiotics, meropenem showed 100% sensitivity, followed by imipenem (97.4%), amikacin (91.8%), and tobramycin (83.5%). In contrast, the high frequencies of resistance were observed with cefixime (93.2%), cefotaxime (78.7%), and ceftriaxone/cefotaxime (71.2%). In conclusion, carbapenems and aminoglycosides are highly recommended for the empirical treatment of UTIs, while, Quinolones, penicillins, and cephalosporins are not suggested. Frequent antibiotics susceptibility testing are warranted to determine the resistance pattern of UTI bacteria.

• Neonatal Medicine
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• v.17 no.1
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• pp.84-93
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• 2010

Purpose : This study was performed to estimate the incidence of nosocomial sepsis and to identify the most relevant risk factors for nosocomial sepsis in high-risk very low birth weight (VLBW) infants. Methods : A retrospective review of 341 VLBW infants, admitted to the Neonatal Intensive Care Unit of the Eulji University Hospital (Daejeon & Seoul) between January 2002 and June 2009, who survived more than 72 hours was performed. The incidence, causative organisms, risk factors and prognosis of nosocomial sepsis in VLBW infants were analyzed. Results : The incidence of nosocomial sepsis was 16.1% and the onset date of nosocomial sepsis was 21.5$\pm$15.9 days (mean$\pm$SD) after delivery. Staphylococcus aureus (21.3%) was the most common organism in the patients with nosocomial sepsis in VLBW infants. The multiple logistic regression analysis showed that, gestational age [odds ratio (OR), 0.87; 95% CI, 0.83-0.91], umbilical artery catheter use for more than 5 days (OR, 2.2; 95% CI, 1.15-4.46), umbilical venous catheter use for more than 5 days (OR, 2.1; 95% CI, 1.11-4.16), peripheral arterial line use (OR, 2.1; 95% CI, 1.14-4.04) and intravenous intralipids (OR, 4.3;95% CI, 1.13-14.32) were identified as risk factors. Conclusion : The limited usage of intravascular catheter related procedures and the short providence of intravenous nutrition may decrease the incidence of nosocomial sepsis in VLBW infants.

• Korean Journal of Clinical Pharmacy
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• v.12 no.2
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• pp.55-64
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• 2002

Infection is one of the main causes of death in severe burn cases. Treatment of burn patient includes fluid therapy, wound care, complication care and antibiotic therapy for infection. The objective of this study was to evaluate the characteristics of burn patients, the type of isolated microorganisms and their susceptibility, and the systemic antibiotics used. This is a retrospective study of 126 burn patients treated in the Hanil General Hospital from January to December 2001. Total 126 patients were assessed with 103 males and 23 females (4.5:1). The average age was $34.8\pm17.6$ years and extent of burn $(TBSA\;\%)\;was\;24.5\pm18.5\%$. The burn was caused by electric accident $(47.6\%),\;flame\;(29.4\%),\;scalding\;(21.4\%),\;and\;chemical\;accident\;(1.6\%)$. The overall mortality rate was $7.14\%$ (9/126) and all expired patients were males. The average age (n=9) was $48.8\pm15.6$ yrs and the extent of burn was $65.0\pm19.0\%$. The causes of death were due to flame burns $(13.5\%)$ and electric burns $(6.7\%)$. The culture sites of the isolated microorganisms were wound $(85.3\%),\;sputum\;(9.3\%),\;urine\;(2.7\%),\;blood\;(1.3\%)\;and\;catheter\;tip\;(1.3\%)$. Pseudomonas aeruginosa was the most commonly isolated organism $(35\%)$, followed by Staphylococcus aureus $(30.1\%)$, Acinetobacter baumannii $(21.4\%)$, and Enterococcus spp. $(3.9\%)$. The number of systemic antibiotics administered was 4.5. The classes of the antibiotics were cephalosporines $(38.5\%)$, aminoglycosides $(31\%)$, quinolones $(13.3\%)$, penicillins $(12.4\%)$, carbapenems $(2.4\%)$, glycopeptides $(1.9\%)$ and others $(0.6\%)$. In conclusion, most of burn patients had wound infection and Pseudomonas aeruginosa was the most commonly isolated organism. Cephalosporins were administered the most frequently among antibiotics.

• Archives of Pharmacal Research
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• v.19 no.1
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• pp.46-51
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• 1996

The in vitro activity of LB 10517, a new catechol-substituted cephalosporin, was compared with those of E-1077, cefpirome and ceftazidime 1034 clinical isolates collected in Japan. LB10517 showed a broad-spectrum antibacterial activity against a wide range of grampositive and gram-negative bacteria including non-glucose fermenting rods, Pseudomonas aeruginosa. Against the methicillin-susceptible strains of Staphylococcus aureus (MSSA) and Strptoccus pyogenes, the $MIC_{90}$ values of LB10517 which required to inhibit 90% of the strains wre $3.13\mug/ml\; and\; 0.1\mug/ml$, respectively. It was as active as E-1077 but more active than cefpirome and ceftazidime. Methicillin-resistant strains of S.aureus (MRSA) and Enterococcus spp. were highly resistant to all the test compunds. LB10517 was highly active against most members of the family Enterobacteriaceae, 90% of which were inhibited at a concentration of less than $0.78\mug/ml$, except for Enterobacter cloacae ($1.56\mug/ml$) and Serratia marcescens ($3.13\mug/ml$)Its activity was comparable to those of E-1077 and cefpirome but it was greater than that of ceftazidime. Against Pseudomonas aeruginosa, LB10517 showed the most potent antibacterial activity among the compounds tested. Ninety percent of P. aeruginosa isolates were susceptible at the concentration of $0.39\mug/ml$. Its activity was 32-to 128 fold higher than those of E-1077, cefpirome and ceftazidime. Against imipenem- or ofloxacin-resistant P. aeruginosa, LB10517 with $MIC_{90}\; of\; 6.25 \\mug/ml\; and\; 3.13\mug/ml$, respectively, showed 16-fold more potent activity than the other test compounds. LB10517 showed a relatively high plasma level and long plasma elimination half-life in rats $(t_{1/2}(\beta,\; 52 min)\; and\; dogs\; (t_{1/2}(\beta),\; 103 min)$.

• Journal of Yeungnam Medical Science
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• v.16 no.1
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• pp.60-68
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• 1999

A nationwide survey was conducted to investigate the annual occurrence rate of neonatal sepsis, maternal risk factors in neonatal sepsis, localized infection in neonates, causative organisms in nosocomial infection and the most common causative organism for neonatal sepsis in Korea. Clinical and bacteriological data wele collected from 37 neonatal units to perform retrospective review of the medical records of the newborn infants who were confirmed as having neonatal sepsis and whose blood culture was collected to isolate organisms for one year study period from January to December in 1997. 78,463 neonates were born at 37 hospital in 1997, and 20,869 neonates were admitted to the neonatal units, During this period, 772 episodes of neonatal sepsis were recorded in 517 neonates. The occurrence rate of neonatal sepsis was 0.73%(0~2.95%). Male to female ratio was 1.15:1, and 303 cases(42.1%) were born prematurely. The main pathogens of early onset of sepsis were S. aureus(20%), S. epidermidis(14.4%) and coagulase negative staphylococcus(14. 4%). Gram negative bacilli including Enterobacter spp (7.2%), E. coli(5.1%), Klepstella(4.5%), Pseudomonas(3.7%) and Enterobacter faectum(3.6%) accounted for 24.1% of sepsis. Group B beta-hemolytic streptococcus were isolated only in two cases. Common obstetric factors were PROM(21.1%), difficulty delivery(18.7%), fetal tachycardia(5.3%), chorioamnionitis(4.9%), and maternal fever(4.7%). The main pathogens of late-onset sepsis were S. aureus(22.3%), S. epidermidis(20.4%) and CONS(9.9%). There were 6 cases(1.0%) of Candida sepsis, Frequent focal infections accompanying sepsis were pneumonia(26.1%), urinary tract infection(10.5%), meningitis(8.2%), and arthritis(3.6%), S. epidermidis(22.0%) and s. aureus(21.7%) were also the most common pathogens in 373 nosocomial infection.