BACKGROUND: We evaluated the reliability and accuracy of the combined use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) bacterial identification and Vitek 2 antimicrobial susceptibility testing (AST) for bacteria from positive blood culture bottles. METHODS: Direct identification and AST were performed in parallel to the standard methods in monomicrobial positive blood culture bottles. In total, 254 isolates grown on aerobic and/or anaerobic bottles were identified with MALDI-TOF Vitek MS (bioMerieux, France), and 1,978 microorganism/antimicrobial agent combinations were assessed. For isolates from anaerobic bottles, an aliquot of the culture broth was centrifuged, washed, and filtered through a nylon mesh. For isolates from aerobic/pediatric bottles, a lysis step using 9.26% ammonium chloride solution and 2% saponin solution was included. RESULTS: The overall correct identification rate was 81.8% (208/254) and that for gram-positive/gram-negative isolates was 73.9%/92.6%, respectively, and it was 81.8%, 87.6%, and 57.9% for isolates from aerobic, anaerobic, and pediatric bottles, respectively. Identification was not possible in 45 cases, and most of these isolates were streptococci (N=14) and coagulase-negative staphylococci (N=11). Misidentification occurred only in one case. Compared with standard methods, direct AST showed 97.9% (1,936/1,978) agreement with very major error of 0.25%, major error of 0.05%, and minor error of 1.8%. CONCLUSIONS: This simple and cost-effective sample preparation method gives reliable results for the direct identification and AST of bacteria. For the identification of streptococci and coagulase-negative staphylococci, the method should be further improved.
Adult ; Ammonium Chloride/chemistry ; Anti-Infective Agents/*pharmacology ; Child ; Gram-Negative Bacteria/drug effects/*isolation & purification/metabolism ; Gram-Positive Bacteria/drug effects/*isolation & purification/metabolism ; Humans ; Reagent Kits, Diagnostic ; Saponins/chemistry ; *Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization

OBJECTIVETo determine the frequency distribution and antibiotic resistance of pathogens isolated from the cerebrospinal fluid samples of children with bacterial meningitis (BM) and to provide a basis for the timely and effective treatment of childhood BM.

METHODSRetrospective analysis was performed on pathogens isolated from 5097 cerebrospinal fluid samples collected from children in Kunming Children's Hospital between January 2008 and June 2012, as well as drug sensitivity test results. Kirby-Bauer antibiotic testing was used to analyze the sensitivity of these pathogens to commonly used antibiotics.

RESULTSA total of 116 pathogen strains were detected from the 5097 cerebrospinal fluid samples, including 77 (66.4%) Gram-positive strains, 30 (25.9%) Gram-negative strains, and 9 (7.8%) fungal strains, with a positive rate of 2.28%. The six most frequently isolated pathogens were Staphylococcus epidermidis (32 strains, 27.6%), Streptococcus pneumoniae (15 strains, 12.9%), Escherichia coli (15 strains, 12.9%), Staphylococcus haemolyticus (9 strains, 7.8%), Cryptococcus neoformans (8 strains, 6.9%) and Staphylococcus aureus (6 strains, 5.2%). Coagulase-negative staphylococci was the predominant pathogen in neonates and young infants with BM, and its sensitivity rates to penicillin, erythromycin and clindamycin were lower than 40%. Streptococcus pneumoniae had a penicillin sensitivity rate of 13.4%, while sensitivity rates to erythromycin and clindamycin reached 60.0%. No Staphylococcus and Streptococcus pneumoniae pathogens resistant to vancomycin were found. Gram-negative bacilli had relatively high sensitivity rates to imipenem, meropenem, cefoperazone/sulbactam and cefepime.

CONCLUSIONSGram-positive cocci are the predominant pathogens for childhood BM over the past five years. The detected pathogens develop high resistance to commonly used antibiotics. To prevent misdiagnosis, careful attention should be paid to BM caused by Cryptococcus neoformans.

Child ; Child, Preschool ; Drug Resistance, Bacterial ; Female ; Gram-Negative Bacteria ; drug effects ; isolation & purification ; Gram-Positive Cocci ; drug effects ; isolation & purification ; Humans ; Infant ; Infant, Newborn ; Male ; Meningitis, Bacterial ; cerebrospinal fluid ; drug therapy ; microbiology ; Retrospective Studies

OBJECTIVESTo describe the microbiology, antimicrobial susceptibility of patients proven prosthetic joint infection (PJI) after primary total knee arthroplasty (TKA)and to provide reference for the diagnosis and treatment of this complication.

METHODSThe medical data of the patients with infected knee arthroplasty, who were managed with revision surgery between January 1995 to December 2011 were reviewed. Twenty-nine cases were identified and majority of the patients were female (23/29). Diagnosis of PJI after primary TKA was between 1 week and 10 years (average 24.3 months). The microbiology and antimicrobial susceptibility were analyzed.

RESULTThe overall positive rate of cultures was 65.5% (19/29). The most common organisms identified were Coagulase-negative Staphylococcus (CNS) (7/19) and Staphylococcus Aureus (SA) (5/19). Rare pathogens of Mycobacterium (2/19) and fungi (1/19) were also identified. Vancomycin was the most effective antibiotics with overall sensitivity rates of 100%.Resistant and rare pathogens were all in type IV infection.

CONCLUSIONSGram-positive bacterias are the main pathogen, resistant and rare pathogens should be payed attention to. Antibiotic treatment for infected TKA should be based on the results of drug susceptibility. Vancomycin allows infected knee arthroplasties before the result.

Aged ; Anti-Bacterial Agents ; pharmacology ; Arthroplasty, Replacement, Knee ; Drug Resistance, Bacterial ; Female ; Gram-Positive Bacteria ; drug effects ; isolation & purification ; Humans ; Knee Prosthesis ; Male ; Microbial Sensitivity Tests ; Middle Aged ; Prosthesis-Related Infections ; microbiology ; Vancomycin ; pharmacology

OBJECTIVETo study the clinical characteristics and antimicrobial resistance of bloodstream infections caused by Gram positive bacteria, so as to provide reference for the rational use of antimicrobial agent.

METHODSOne hundred and eight patients with bloodstream infections of Gram positive bacteria in our hospital from January 2009 to December 2009 were retrospectively reviewed. The clinical manifestations, pathogen types and antimicrobial susceptibility results of pathogens isolated from bloodstream were analyzed.

RESULTSAll patients had fever and 31.89% with rigor, 22.41% of the patients had no local infection lesions, 77.59% had clear infection lesions, including oral infections, respiratory tract infections and soft tissue infections. The pathogen testing showed that 12.82% were staphylococci aureus, 50.42% coagulase-negative staphylococci, 24.8% streptococci, 9.4% enterococci and 2.56% Listeria monocytogenes. Antibiotics resistance of staphylococcus and enterococci in our hospital was severe. The percentage of methicillin-resistant staphylococcus aureus in this investigation was 68.92%. The resistant rates of methicillin-resistant coagulase-negative staphylococci (MRCNS) to the most antimicrobial agents were higher than that methicillin-sensitive coagulase-negative staphylococci. One strain of MRCNS was found resistant to teicoplanin and linezolid, and 1 strain of enterococci resistant to teicoplanin and linezolid.

CONCLUSIONGram positive bacteria shows serious drug resistance, but still keeps highly sensitive to vancomycin, linezolid, teicoplanin and quinupristin/dalfopristin.

Adolescent ; Adult ; Aged ; Child ; Child, Preschool ; Drug Resistance, Bacterial ; Female ; Gram-Positive Bacteria ; drug effects ; isolation & purification ; Gram-Positive Bacterial Infections ; diagnosis ; microbiology ; Hematologic Diseases ; microbiology ; Humans ; Infant ; Male ; Middle Aged ; Retrospective Studies ; Young Adult

OBJECTIVETo analyze the condition of early (≤ 30 d) postoperative pulmonary infection in children after living donor liver transplantation (LDLT).

METHODThe clinical data of 36 cases undergoing LDLT in Children's Hospital of Chongqing Medical University were analyzed retrospectively from June 2006 to December 2009.

RESULTOf 36 cases without preoperative respiratory disease, 17 were boys, 19 were girls. Their age ranged from 2 months to 14 years. Pulmonary infection developed in 24 patients, of whom 4 cases died (17%) and 3 deaths were related to pulmonary infection. Pulmonary infection occurred in 17 of 20 infants (85%) and 10 of 11 cases (91%) with liver function of Child-Pugh grade C. Twenty cases (83%) developed pulmonary infection within first 2 weeks after LDLT. Totally 65 pathogenic strains of microorganisms were isolated, in which Gram-negative bacteria, Gram-positive bacteria and fungi were 46 strains, 5 strains, 14 strains respectively. The most frequently isolated bacteria were Pseudomonas aeruginosa (14 strains), Klebsiella pneumoniae (8 strains) and Acinetobacter baumannii (8 strains). Pseudomonas aeruginosa showed a resistance rate of almost 100% to cotrimoxazole, tetracycline, chloramphenicol, ampicillin, the first, the second and some of the third generation cephalosporins. Klebsiella pneumoniae producing extended spectrum beta-lactamase had a resistance rate of almost 100% to beta-lactams except carbapenems. Acinetobacter baumannii was exquisitely susceptible to carbapenems, but showed a high resistance to penicillins and cephalosporins. Candida albicans, which was the most common fungus, showed a susceptibility rate of 100% to amphotericin B. In the LDLT recipients of pulmonary infection, cytomegalovirus (CMV) infections occurred in 2 patients and Epstein Barr virus (EBV) infection in 1 patient.

CONCLUSIONThe incidence of early postoperative pulmonary infection was high in children undergoing LDLT, especially in infants. And the mortality should not be ignored. The high risk period for infection was within the first 2 weeks after operation. The pathogens were mainly Gram-negative bacteria, which showed high and multidrug resistance.

Adolescent ; Anti-Bacterial Agents ; therapeutic use ; Antifungal Agents ; therapeutic use ; Bacterial Infections ; drug therapy ; etiology ; microbiology ; Child ; Child, Preschool ; Drug Resistance, Bacterial ; Female ; Gram-Negative Bacteria ; drug effects ; isolation & purification ; Gram-Positive Bacteria ; drug effects ; isolation & purification ; Humans ; Infant ; Liver Transplantation ; Living Donors ; Lung Diseases ; drug therapy ; etiology ; microbiology ; Male ; Postoperative Complications ; drug therapy ; epidemiology ; etiology ; Retrospective Studies ; Risk Factors

OBJECTIVE: To investigate the bacterial distribution and resistance to antibiotics in culture-positive urine, and to provide reference for rational use of antibiotics in clinical practice. METHODS: Distribution and antibiotic resistance to pathogens in 658 culture-positive patients from Jan. 1, 2007 to Dec. 31, 2008 were analyzed. RESULTS: (1)Pathogenic strains from the 658 patients were collected from the urine specimen in the survey, which included Gram-negative bacilli (70.82%), Gram-positive cocci (26.14%) and fungi (3.04%). The distribution rate of Escherichia coli declined from 68.91% in 2008 to 63.43% in 2007 (P>0.05), and Enterococcus rose from 3.37% to 7.67% (P>0.05), but the difference was not significant. The proportion of Gram-negative bacilli (especially the E.coli) from patients in the Emergency Department and Out-patient Department was higher than that from in-patients, and the proportion of K. pneumonia and Gram-positive bacteria was lower than in-patients, both with significant differences (P<0.05). (2) The resistance rate of E. coli and K. pneumonia to quinolones was 28.57%-56.25%, and the resistance rate to 3rd generation cephalosporin was 38.78%-65.78%, respectively. The resistance rate of Gram-positive cocci to quinolones and 3rd generation cephalosporin was both higher than 50%, and was 11.05% to Vancomycin. CONCLUSION Gram-negative bacilli such as E. coli and K. pneumonia are predominant organism in the urinary tract infections, but proportion of Gram-positive bacteria has increased in recent years. Attention needs to be paid to the overall and severe bacterial resistance in the urinary tract infections and rational use of antibiotics.
Adult ; Anti-Infective Agents, Urinary ; pharmacology ; Drug Resistance, Bacterial ; Escherichia coli ; drug effects ; isolation & purification ; Female ; Gram-Negative Bacteria ; isolation & purification ; Gram-Positive Bacteria ; isolation & purification ; Humans ; Male ; Retrospective Studies ; Urinary Tract Infections ; drug therapy ; microbiology ; Urine ; microbiology

OBJECTIVETo investigate the distribution and the drug resistance pattern of pathogenic bacteria isolated from pediatric cases suffering from wounds infection following the Wenchuan earthquake.

METHODSOf the ninety-eight injured children, 50 had wound infection diagnosed by clinical examination. Specimens for culture were collected from the fifty injured children and the results of bacterial identification and antibiotic resistance were retrospectively reviewed.

RESULTSIn the fifty injured children with wound infection, microbial growth was detected in 31 (62.0%) and 21 children suffered from mixed infections (the infection rate was 67.7%). Ninety-nine pathogens were isolated, gram positive bacteria accounted for 16.16% (16 strains), Gram negative bacteria accounted for 81.82% (81 strains), and fungus 2.02% (2 strains). Staphylococcus aureus (5 strains, 5.05%), Enterococcus faecalis (3 strains, 3.03%) and Enterococcus faecium (2 strains, 2.02%) were the primary Gram-positive bacteria identified and Gram-negative infections typically included Acinetobacter baumanii (27 strains, 27.27%), Enterobacter cloacae (18 strains, 18.18%) and Pseudomonas aeruginosa (13 strains, 13.13%). Acinetobacter baumanii was the most common organism isolated from wounds. Duration of being szeged and complications had a significant association with wound infection with Acinetobacter baumanii. Drug sensitivity tests displayed that the isolated bacteria were highly resistant to common antibiotics. One strain of Acinetobacter baumanii-calcoaceticus complex and six strains of Acinetobacter baumanii were resistant to all common antibiotics including imipenem/cilastatin. Vancomycin-resistant Gram-positive bacteria were not identified.

CONCLUSIONFollowing the Wenchuan earthquake disaster, wound infection profiles of pediatric patients were significantly different, Acinetobacter baumanii was the main common organism isolated from wounds in contrast to the previous low isolation rate. The isolated bacteria were highly and multiple drug resistant and it was difficult to treat. Knowing the distribution and the drug resistance pattern of pathogen is of paramount importance in guiding the clinical treatment.

Adolescent ; Child ; Child, Preschool ; Disasters ; Drug Resistance, Bacterial ; Earthquakes ; Female ; Gram-Negative Bacteria ; drug effects ; isolation & purification ; Gram-Positive Bacteria ; drug effects ; isolation & purification ; Humans ; Male ; Microbial Sensitivity Tests ; Wound Infection ; microbiology ; Wounds and Injuries ; microbiology

OBJECTIVETo analyze the characteristic of bacterial infections, and the relationship between antibiotics treatment and bacterial infections after liver transplantation, and to prevent antibiotic-resistant bacterial infections.

METHODS86 liver transplant recipients were retrospected. Different indexes including limited daily dose, the frequency of medication, drug use index were used to evaluate the rationality of the use of antibiotics, three-dimensional test was used to explore extended-spectrum beta-lactamase and AmpC enzyme of Gram-negative bacteria.

RESULTSThe major pathogens of infection after liver transplantation were Enterococcus faecalis, Enterobacter cloacae, fungi and E. coli. Pre-operative antibiotic utilization rate was 83.7%, it was mainly a single use of antibiotics; After- operative antibiotic usage was 100.0%, it was mainly joint use of two or three antibiotics; The top 3 antibiotics used were cephalosporins, the combined enzyme inhibitors and penicillin. Antibiotics with drug utilization index (DUI) more than 1.1 included ampicillin and Lalin proxy. 43.3% and 31.8% of Gram -Negative bacteria produced ESBLs and AmpC, respectively, while 21.3% Gram -Negative bacteria produced two enzymes.

CONCLUSIONThere is high incidence of bacterial infections after liver transplantation. The use of antibiotics is high dose, high-frequency and reasonable; High resistance of bacterial infections was prone to develop and the prevention of the high resistance of bacterial infections is very important.

Adolescent ; Adult ; Aged ; Anti-Bacterial Agents ; administration & dosage ; therapeutic use ; Bacterial Infections ; drug therapy ; etiology ; microbiology ; Child ; Child, Preschool ; Drug Resistance, Bacterial ; Female ; Gram-Negative Bacteria ; drug effects ; enzymology ; isolation & purification ; Gram-Positive Bacteria ; drug effects ; enzymology ; isolation & purification ; Humans ; Infant ; Liver Transplantation ; adverse effects ; methods ; Male ; Microbial Sensitivity Tests ; Middle Aged ; Postoperative Complications ; drug therapy ; epidemiology ; microbiology ; Retrospective Studies ; Young Adult ; beta-Lactamases ; biosynthesis

BACKGROUND: Procedures for rapid identification and susceptibility testing by direct inoculation (DI) from positive blood culture bottles into an automated system have not been standardized. This study was purposed to evaluate DI from BACTEC 9240 blood culture system (BD, USA) into MicroScan (Dade Behring, USA) or Phoenix (BD, USA). METHODS: From May to June 2006, bacterial pellets from positive aerobic bottles showing gram-positive cocci (GPC) or gram-negative rods (GNR) of single morphology were directly inoculated to MicroScan PosCombo1A and NegCombo32 and to Phoenix PMIC/ID-107 and NMIC/ID-53. In addition, the automated instruments were also inoculated from subcultures (standard inoculations, SI). Species identification and susceptibilities were compared between DI and SI and between MicroScan and Phoenix. RESULTS: A total of 108, 104, and 78 specimens were tested with MicroScan, Phoenix, and both, respectively. When DI and SI were matched, 94.8% of GPC were correctly identified with MicroScan, compared to 80.7% with Phoenix, and 93.9% of GNR were correctly identified with MicroScan, compared to 95.7% with Phoenix. DI with MicroScan and Phoenix showed correct susceptibilities in 94.6% of 1,150 and 96.5% of 660 tests (with very major error [VME] of 1.1% and 1.1%), respectively, among GPC and in 94.4% of 942 and 96.3% of 781 tests (with VME of 0.6% and 0%), respectively, of GNR. Correlation of identification/susceptibilities between MicroScan and Phoenix using DI were 81.8%/98.0% for Staphylococcus aureus and 100.0%/95.6% for Escherichia coli. CONCLUSIONS: DI warrants a reliable method for identification and susceptibility testing of both GPC and GNR in MicroScan, and those of only GNR in Phoenix.
Automation ; Bacterial Typing Techniques/instrumentation/*methods ; Culture Media ; Gram-Negative Bacteria/*classification/drug effects/isolation & purification ; Gram-Negative Bacterial Infections/blood/*microbiology ; Gram-Positive Bacterial Infections/blood/*microbiology ; Gram-Positive Cocci/*classification/drug effects/isolation & purification ; Humans ; Microbial Sensitivity Tests/instrumentation/*methods ; Reagent Kits, Diagnostic ; Sensitivity and Specificity

OBJECTIVETo analyze the strains of bacteria in burn infection and their resistance to antibiotics in our burn unit in the recent years.

METHODSBacteria were isolated from specimens from the wounds, venous lines, blood, urine and feces of the hospitalized burn patients from January 2003 to December 2005 to analyze the vicissitude of bacteria and their drug resistance.

RESULTSThe number of Gram-negative bacteria (372 strains) was larger than Gram-positive ones (292 strains). Staphylococcus aureus (accounting for 16.7%) was predominant among Gram-positive bacteria, among which methicillin resistant staphylococcus aureus (MRSA) accounted for 82.5%. Among the Gram-negative bacteria, Pseudomonas aeruginosa accounted for 12.5%, and Escherichia coli accounted for 11.1%. The drug resistant ESPL-producing strains of Escherichia coli and Klebsiella pneumoniae accounted for 60.8% and 42.9%, respectively.

CONCLUSIONDrug resistance to antibiotics is a serious problem in a burn unit, calling for monitoring the vicissitude of bacteria strains and antibiotics sensitivity in order to control bacterial infection and dissemination.

Adolescent ; Adult ; Aged ; Anti-Bacterial Agents ; pharmacology ; Bacterial Infections ; microbiology ; Burn Units ; Burns ; microbiology ; Child ; Child, Preschool ; Drug Resistance, Bacterial ; Female ; Gram-Negative Bacteria ; drug effects ; isolation & purification ; Gram-Positive Bacteria ; drug effects ; isolation & purification ; Humans ; Male ; Middle Aged ; Young Adult