Cytocentrifuge Gram stain method and urine dipstick test as a screening test of bacteriuria / 대한임상병리학회지

BACKGROUND: Rapid detection of bacteriuria is desirable for diagnosis and treatment of urinary tract infections. The aim of this study was to assess the usefulness of the cytocentrifuge Gram stain, uncentrifuged Gram stain, and urinary nitrite, leukocyte esterase to determine the exclusion of urine culture. METHODS: A cytocentrifuge Gram stain procedure and urine dipstick test were performed to screen for bacteriuria using 155 random fresh urine specimens submitted for routine culture. The authors compared the results of the cytocentrifuge Gram stain, urinary nitrite, leukocyte esterase and multiapplication of three tests with the results of culture. Result: Compared with positive urine culture(>105CFU/mL), cytocentrifuge Gram stain had a good negative predictive value(96.0%) and sensitivity(89.1%). The urinary nitrite and leukocyte esterase test had very low sensitivity(27.0%, 45.9%), respectively. The multiapplication of cytocentrifuge Gram stain, urinary nitrite and leukocyte esterase had a excellent negative predictive value(98.9%) and sensitivity(97.3%), and agree with urine culture positive(36/37 cases, 97.3%). CONCLUSION: Multiapplication of urinary cytocentrifuge Gram stain, nitrite and leukocyte esterase test is a useful screening test for the rapid exclusion of bacteriuria and provides rapid morphologic information about suspected pathogens in cases with positive urine culture.

Detection of Penicillin-resistant Streptococcus pneumoniae by Polymerase Chain Reaction / 대한임상병리학회지

BACKGROUND: Resistance to penicillin of Streptococcus pneumoniae in clinical isolates has occurred by the development of altered penicillin-binding proteins (PBPs) that have greatly decreased affinity for antibiotics and has been encountered with increasing frequency in Korea. In this study, the identification of altered PBPs of S. pneumoniae in clinical isolates by using polymerase chain reaction (PCR) and relationship of PCR with the conventional antibiotic susceptibility test of penicillin were evaluated. METHODS: Thirty isolates of S. pneumoniae from clinical specimens were used. Four sets of PCR primers of penicillin-sensitive and -resistant S. pneumoniae were designed to amplify (i) PBP 2BS: a 360 base pair fragment of the PBP 2B gene, (ii) PBP 2BCA: a 350 base pair fragment of the class A mutations present in PBP 2B gene, (iii) PBP 2BCB: a 295 base pair fragment of the class B mutations present in PBP 2B gene, and (iv) PBP 1AR: a 434 base pair fragment of the PBP 1A gene. In addition, a set of primers that amplify 273 base pair of the autolysin gene (ALY) was applied in combination with the above to identify S. pneumoniae. PCR results were compared with antibiotic susceptibility test (disk diffusion test and penicillin MIC). RESULT: Among 30 clinical isolates tested, 80% of isolates were penicillin resistant. The results of antibiotic susceptibility test were same as those of PCR methods. Among 24 penicillin resistant isolates detected by PCR methods, 5 isolates revealed PBP 2BCB gene, but 19 isolates revealed both of PBP 2BCB and 1AR genes. Five isolates with PBP 2BCB gene showed lower range of penicillin MIC (0.19 ~ 1.0 g/mL) than 19 isolates with PBP 2BCB and 1AR genes (0.75 ~ 4.0 g/mL). CONCLUSION: Detection of altered PBP genes of S. pneumoniae by PCR may be performed for the study of penicillin resistance. This study indicates that more altered PBPs in 1AR genes are related with higher MICs.