Antibiotic resistance is a major global concern and challenge in the 21st century. Enterobacteriaceae are one of the important pathogens of hospital-acquired infections. With the increasing use of antibiotics in clinical practice, a variety of drug-resistant Enterobacteriaceae, especially multidrug-resistant Enterobacteriaceae have emerged, posing an increasingly serious threat to human health. Bacteria can acquire antibiotic resistance by mutation or horizontal transfer of antibiotic resistance genes, and it is often possible to predict the corresponding resistance phenotype from known mechanism. However, recent findings suggest that genetic background and environmental factors could alter the expression of specific resistance genes and that a given genotype does not always generate the expected resistance phenotype. The genotype-phenotype segregation greatly hampers our ability to predict antibiotic resistance phenotype from a genetic perspective. In this review, we explore the genetic and environmental regulation of the expression of antibiotic resistance genes in a variety of Enterobacteriaceae, with the aim to provide scientific evidence for genetic prediction of antibiotic resistance phenotype and clinical guidance on drug use.
Anti-Bacterial Agents/pharmacology* ; Bacteria ; Cross Infection ; Drug Resistance, Microbial ; Enterobacteriaceae/genetics* ; Humans

Objective: To investigate the epidemiological characteristics of measles outbreak caused by genotype D8 virus in Pinghu city of Zhejiang province, and provide evidence for the control of the outbreak. Methods: The measles outbreak data were collected through National Measles Surveillance System. The outpatient records and admission records were checked, field investigation and outbreak response were conducted. Blood samples in acute phase and swab specimens were collected from the patients for laboratory testing, including serology test, RNA extraction and amplification, measles virus isolation and genotype identification. Software SPSS 17.0 and Excel 2016 were used for data analysis. Results: A total of 10 confirmed measles cases were reported in Pinghu city, and 8 cases were aged >40 years. Six blood samples were collected, in which 5 were measles D8 virus positive and 1 was negative in measles virus detection. There were epidemiological links among 10 cases which occurred in a factory, a hospital and a family at the same time. There was no statistical difference in symptoms among cases caused by D8 virus and H1a virus. After the emergent measles vaccination, the measles outbreak was effectively controlled. Conclusion: Untimely response due to the uneasy detection of measles cases in the early stage, nosocomial infection and weak barrier of measles immunity in adults might be the main reasons for this outbreak. Measles vaccination is effective in the prevention of measles D8 virus infection. It is necessary to strengthen measles genotype monitoring for the tracing of infection source and control of outbreaks.
Adult ; Amplified Fragment Length Polymorphism Analysis ; Child ; Cross Infection ; Disease Outbreaks ; Genotype ; Hospitalization ; Humans ; Measles/virology* ; Measles virus/isolation & purification* ; Outpatients ; Population Surveillance ; RNA, Viral/genetics* ; Sequence Analysis, DNA

OBJECTIVETo analyze the drug resistance and drug resistance genes of imipenem-resistant Pseudomonas aeruginosa (IRPA) strains isolated from burn wards.

METHODSFrom June 2011 to June 2012, 30 strains of IRPA were isolated from wound excretion, sputum, and venous catheter attachment from burn patients hospitalized in Guangzhou Hospital of Integrated Traditional Chinese and Western Medicine. Drug resistance of the IRPA to 12 antibiotics commonly used in clinic, including ceftazidime, amikacin, ciprofloxacin, etc., was tested with K-B paper agar disk diffusion method. Metallo-β-lactamase (MBL)-producing IRPA was detected by synergism test with imipenem-2-mercaptoethanol. Plasmid of IRPA was extracted, and it was inserted into competent cells, producing transformation strains (TSs). Drug resistance of TSs to imipenem and the MBL-producing TSs were detected. The genes blaIMP, blaVIM, blaOXA-1, blaOXA-2 and blaOXA-10 of IRPA and the TSs were detected by polymerase chain reaction. The drug resistance of IRPA producing MBL or OXA enzyme was summed up.

RESULTSThe sensitive rates of the 30 strains of IRPA to the 12 antibiotics were equal to or above 60.0%. Six strains of MBL-producing IRPA were screened. Twenty-four TSs were resistant to imipenem, and 6 strains among them were MBL-producing positive. Among the 30 strains of IRPA, 6 strains and their corresponding TSs carried blaVIM; 20 strains and their corresponding TSs carried blaOXA-10; no strain was detected to carry blaIMP, blaOXA-1 or blaOXA-2. Two strains and their corresponding TSs were detected carrying both blaVIM and blaOXA-10. No significant difference of drug resistance was observed between strains producing only MBL or OXA enzyme, with the same high resistance to β-lactam antibiotics and some degree of sensitivity to aminoglycoside antibiotics. Strains producing enzymes MBL and OXA were all resistant to the 12 antibiotics.

CONCLUSIONSIRPA strains isolated from burn wards of Guangzhou Hospital of Integrated Traditional Chinese and Western Medicine are multidrug-resistant, and they mainly produce type B and D carbapenemases.

Burns ; microbiology ; Cross Infection ; microbiology ; Drug Resistance, Multiple, Bacterial ; genetics ; Humans ; Imipenem ; Microbial Sensitivity Tests ; Pseudomonas aeruginosa ; drug effects ; genetics ; isolation & purification

BACKGROUND: We investigated the rates of fecal transmission of extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae (ESBL-E) and carbapenem-resistant Enterobacteriaceae (CRE) among patients admitted to intensive care units (ICUs). METHODS: From June to August 2012, rectal cultures were acquired from all patients at ICU admission. For patients not carrying ESBL-E or CRE at admission, follow-up cultures were performed to detect acquisition. A chromogenic assay was used to screen for ESBL-E and CRE. Bacterial species identification and antibiotic susceptibility tests were performed using the Vitek 2 system (bioMerieux, France). ESBL genotypes were determined by PCR, and clonal relatedness of the isolates was assessed by pulsed-field gel electrophoresis. RESULTS: Out of 347 ICU admissions, 98 patients were found to be carriers of ESBL-E (28.2%, 98/347). Follow-up cultures were acquired from 91 of the patients who tested negative for ESBL-E at admission; the acquisition rate in this group was 12.1% (11/91), although none was a nosocomial transmission. For CRE, the prevalence of fecal carriage was 0.3% (1/347), and the acquisition rate was 2.9% (4/140). None of the CRE isolates were carbapenemase-producers. CONCLUSIONS: The high prevalence of ESBL-E carriage on admission (28.2%), coupled with rare nosocomial transmission and the very low carriage rate of CRE (0.3%), challenge the routine use of active surveillance in non-epidemic settings. Nevertheless, passive surveillance measures, such as rapid and accurate screening of clinical specimens, will be critical for controlling the spread of CRE.
Anti-Bacterial Agents/pharmacology ; Bacterial Proteins/*metabolism ; Carbapenems/*pharmacology ; Carrier State/epidemiology ; Cross Infection/epidemiology/*transmission ; DNA, Bacterial/analysis ; Drug Resistance, Bacterial/drug effects ; Electrophoresis, Gel, Pulsed-Field ; Enterobacteriaceae/enzymology/genetics/*physiology ; Enterobacteriaceae Infections/epidemiology/*transmission ; Feces/*microbiology ; Genotype ; Humans ; Intensive Care Units ; Polymerase Chain Reaction ; Prevalence ; Republic of Korea/epidemiology ; beta-Lactamases/*metabolism

OBJECTIVETo study the clinical and molecular characteristics of methicillin-resistant Staphylococcus aureus (MRSA) infection in children.

METHODA total of 37 MRSA strains were isolated from hospitalized patients in Children's Hospital of Fudan University from March 2009 to November 2011. The clinical characteristics were investigated by a cohort study. Furthermore, the mecA, Panton-Valentine leucocidin (PVL) genes were detected by polymerase chain reaction (PCR), and the genotypes of SCCmec were determined by multiplex PCR.

RESULT(1) Among the 37 MRSA isolates, infections with 21 were acquired from hospital (HA-MRSA), and 16 isolates were acquired from community (CA-MRSA). (2) In the study, MRSA frequently caused respiratory tract infection, and most of the strains were isolated from intensive care unit (ICU). (3) CA-MRSA was most frequently associated with skin and soft tissue infections (SSTI), suppurative tonsillitis, even pneumonia and septicemia. HA-MRSA infection was more aggressive, most frequently associated with pneumonia, septicemia, and central nervous system (CNS) infections, such as meningitis. In children with fever caused by HA-MRSA or CA-MRSA infection, HA-MRSA showed a longer duration of fever, for 10.5 days. C-reactive protein (CRP) level caused by HA-MRSA (63.00 mg/L) was higher than CA-MRSA (9.50 mg/L) , and there were statistically significant differences between the groups (t = 2.5670, P < 0.05). However, there were no statistically significant differences between the groups in white blood cell count (WBC) or procalcitonin (PCT) level. (4) Among 37 MRSA isolates, the whole isolates were mecA gene positive (100%). SCCmec genotyping results showed that the most frequent SCCmec types were type III, 17 isolates, the others including type IV 8 isolates, type II1 isolates, nontypable 11 isolates, type I and type V were not found in this group. Therein, among 21 HA-MRSA isolates, SCCmec III was the most common, 15 isolates, type IV 1 isolates, nontypable 5 isolates; among 16 CA-MRSA isolates, SCCmec type IV was the most common, 7 isolates, type III 2 isolates, type II 1 isolate, nontypable 6 isolates. (5) Among the 37 MRSA isolates, 28 were PVL gene positive; and among 21 HA-MRSA isolates, 17 were PVL gene positive; Among 16 CA-MRSA isolates, 11 were PVL gene positive; There were no statistically significant differences between the groups (χ(2) = 0.735, P > 0.05) .

CONCLUSIONCompared with CA-MRSA, HA-MRSA infection was more aggressive, and induced higher C reactive protein; the dominant epidemic strains of CA-MRSA was SCCmec type IV, and HA-MRSA was SCCmec type III; the positive rate of PVL gene was high.

Adolescent ; Anti-Bacterial Agents ; pharmacology ; Bacterial Proteins ; genetics ; Bacterial Toxins ; genetics ; Bacterial Typing Techniques ; Child ; Child, Preschool ; China ; epidemiology ; Cohort Studies ; Community-Acquired Infections ; epidemiology ; microbiology ; Cross Infection ; epidemiology ; microbiology ; DNA, Bacterial ; genetics ; Female ; Genotype ; Humans ; Infant ; Infant, Newborn ; Male ; Methicillin ; pharmacology ; Methicillin Resistance ; genetics ; Methicillin-Resistant Staphylococcus aureus ; classification ; genetics ; isolation & purification ; Penicillin-Binding Proteins ; Staphylococcal Infections ; epidemiology ; microbiology

Acinetobacter baumannii is an important microorganism responsible for a number of nosocomial outbreaks, in particular, in intensive care units (ICUs). We investigated a nosocomial infection caused by multidrug-resistant (MDR) A. baumannii in a neonatal intensive care unit (NICU) in Korea. A. baumannii isolates were characterized using Etest (AB Biodisk, Sweden), two multiplex PCR assays, and multilocus sequence typing (MLST) scheme. PCR and PCR mapping experiments were performed for detecting and characterizing the determinants of antimicrobial resistance. Eight strains isolated from an NICU belonged to European (EU) clone II and revealed only one sequence type (ST), namely, ST357. All the isolates were susceptible to imipenem but were resistant to amikacin, gentamicin, ceftazidime, cefepime, and ciprofloxacin. To the best of our knowledge, this is the first report of a nosocomial infection in an NICU in Korea caused by ST357 MDR/carbapenem-susceptible A. baumannii strains. This result demonstrates that nosocomial outbreaks of MDR/carbapenem-susceptible strains as well as MDR/carbapenem-resistant isolates may occur in NICUs.
Acinetobacter Infections/diagnosis/*microbiology ; Acinetobacter baumannii/drug effects/genetics/*isolation & purification/metabolism ; Anti-Bacterial Agents/pharmacology ; Bacterial Proteins/genetics ; Cross Infection/*microbiology ; DNA, Bacterial/analysis ; *Drug Resistance, Multiple, Bacterial ; Humans ; Imipenem/pharmacology ; Infant, Newborn ; *Intensive Care Units, Neonatal ; Microbial Sensitivity Tests ; Multilocus Sequence Typing ; Multiplex Polymerase Chain Reaction ; Republic of Korea

OBJECTIVETo monitor genotypes and drug-resistance trend of Acinetobacter baumannii (AB) isolated from burn wards.

METHODSTwenty-six strains of AB isolated from wound secretion, venous catheter, and blood were collected from burn patients hospitalized in our burn wards from November 2008 to February 2009, and June to September 2010. Homogeneous genotype analysis was performed with repetitive extragenic palindromic PCR, and drug-resistance rate to 13 antibiotics including amikacin, gentamicin, etc., which were commonly used in clinic, was tested by K-B paper disk diffusion. The data of drug-resistance rate were processed with chi-square test.

RESULTS(1) Sixteen AB strains were multi-drug resistant (MDR), 9 AB strains were pan-drug resistant (PDR). Among all strains, the resistance rate to gentamicin, piperacillin, piperacillin/tazobactam, cefuroxime, cefotaxime, ceftazidime, cefepime, ciprofloxacin, imipenem, and meropenem was respectively higher than 90.00%; the resistance rate against cefoperazone/sulbactam was the lowest (11/26, 42.31%). There were obvious difference among the drug-resistance rates of AB strains to 13 antibiotics (with rates from 42.31% to 100.00%, χ(2) = 97.371, P < 0.05). (2) There were 7 genotypes among 26 AB strains, respectively type A (17), type B (3), type C (2), type D (1), type E (1), type F (1), and type G (1). Out of the 17 AB strains in A genotype, 1 strain was from 2008, 1 strain was from 2009, 15 strains were from 2010, and among them 11 strains were collected from wound secretion and 6 strains were obtained from blood and venous catheter.

CONCLUSIONSAB strains in A genotype are dominant in our burn wards in recent years, which are MDR or PDR to commonly used antibiotics. Cefoperazone/sulbactam is the drug of choice for burn patients with AB infection.

Acinetobacter Infections ; epidemiology ; microbiology ; Acinetobacter baumannii ; drug effects ; genetics ; Burns ; microbiology ; Cross Infection ; epidemiology ; microbiology ; Drug Resistance, Multiple, Bacterial ; Genes, Bacterial ; Humans

OBJECTIVETo identify the etiology of an aseptic encephalitis outbreak (ten cases) in a hospital of Xiamen city from 11 to 17 May, 2011.

METHODSA total of ten patients' throat swabs, anal swabs and cerebrospinal fluid were collected and detected by RT-PCR for pan-enterovirus. The samples containing detectable pan-enterovirus were tested by PCR with genotype-specific general primers located in VP1 region of enterovirus genotype A, B and C (HEV-A, B and C). The PCR products of VP1 segment were purified and sequenced, and phylogenetic analysis was performed. Meanwhile, the pathogens in those samples were isolated in Vero cell culture. Homologous analysis of VP1 sequences were carried out for the cultured virus samples and the original clinical samples to identify the outbreak etiology.

RESULTSAmong the ten cases, seven cases were positive for pan-enterovirus nucleic acid. When tested by genotype-specific PCR, the throat and anal swab samples from those 7 patients were positive with HEV-B VP1 primers. Meanwhile, the HEV-B VP1 segments were sequenced and phylogenetic analyzed, which indicated the seven cases were all infected by enterovirus Echo 30. The sequences from those samples had homology of 95.3% - 97.1% with the epidemic strains in Zhejiang, 2004. Out of the seven cases, the sequences of XM2, XM3, XM4, XM8 throat swab samples and XM3, XM6 throat samples showed 99.4% - 100.0% homology which were different from the sequence of XM1, and the homology was 92.8% - 93.4%. Furthermore, the viruses were isolated using Vero cells from XM1, XM2, XM3, XM4 and XM8 throat swab samples, and the VP1 sequence showed more than 99.9% homology with the original specimens.

CONCLUSIONThe local outbreak of aseptic encephalitis was caused by Echo 30 of enterovirus genotype B, and the epidemic strains may have different genetic background.

Child, Preschool ; China ; epidemiology ; Cross Infection ; epidemiology ; virology ; Disease Outbreaks ; Encephalitis ; epidemiology ; virology ; Enterovirus ; genetics ; Enterovirus B, Human ; genetics ; Female ; Genotype ; Humans ; Male ; Molecular Sequence Data

We investigated molecular epidemiology of methicillin-resistant Staphylococcus aureus (MRSA) isolated at 10 intensive care units (ICUs) in Korea. MRSA isolates from bacteremia and nasal colonization were collected prospectively from October 2008 through May 2009 at 10 University-affiliated hospital ICUs. A total of 83 and 175 MRSA strains were isolated from bacteremia and nasal colonization, respectively. Acquired group accounted for 69.9% (n = 58) of bacteremia and 73.1% (n = 128) of nasal colonization. Pulsed-field gel electrophoresis (PFGE) type B (SCCmec type II/ST5) was dominant in the acquired group followed by PFGE type D (SCCmec type IVA/ST72; a community genotype). Seven of 58 (12.1%) acquired bacteremia and 15 of 128 (11.8%) acquired nasal colonizations had SCCmec type IVA/ST72 genotype, which indicated that the community genotype had already emerged as a cause of ICU acquired MRSA infection or colonization. Antibiotic resistance rates to ciprofloxacin, tetracycline, clindamycin and trimethoprim/sulfamethoxazole were 84.4%, 67.1%, 78.1%, and 12.0%, respectively. Susceptibility to ciprofloxacin best predicted a community genotype (sensitivity 96.5%; specificity 96.9%; odds ratio 861; 95% confidence interval 169-4,390, P < 0.001) and the positive predictive value was 90.2%. Among 23 nasal re-colonized strains, 7 MRSA strains (30.4%) were different from the originally colonized strains on the basis of PFGE types.
Adolescent ; Adult ; Aged ; Aged, 80 and over ; Bacteremia/*epidemiology/microbiology ; Cross Infection/epidemiology/genetics ; Drug Resistance, Multiple, Bacterial ; Electrophoresis, Gel, Pulsed-Field ; Female ; Genotype ; Humans ; *Intensive Care Units ; Male ; Methicillin-Resistant Staphylococcus aureus/*genetics/isolation & purification ; Microbial Sensitivity Tests ; Middle Aged ; Molecular Epidemiology ; Molecular Typing ; Nasal Lavage Fluid/*microbiology ; Prospective Studies ; Republic of Korea/epidemiology ; Staphylococcal Infections/*epidemiology/genetics/microbiology

OBJECTIVETo analyse the distribution, drug resistance and epidemiology of pathogenic bacteria in the burn wards of Ruijin Hospital.

METHODSSeventeen strains of Methicillin resistant staphylococcus aureus (MRSA), 52 strains of Pseudomonas aeruginosa (PA), and 11 strains of Acinetobacter baumannii (AB) isolated from the wound secretion, venous catheters, blood, urine and stool etc. were collected from burn patients hospitalized in our department from January 2004 to December 2006. The distribution and the drug resistance profile of bacteria were analyzed, and the homology analysis was performed by randomly amplified polymorphic DNA (RAPD).

RESULTSMRSA, PA and AB were the major strains in our burn wards in recent years, of which Staphylococcus aureus (SA) was the most dominant. During these 3 years, MRSA accounted for 77% (63/82), 85% (63/74), and 75% (74/99), respectively, for SA isolated in this period. MRSA was resistant to Amikacin, Gentamicin, Erythromycin, Clindamycin and Levofloxacin; PA was resistant to Amikacin, Gentamicin, Piperacillin, Ceftazidime, Cefoperazone, Aztreonam and Imipenem; AB was resistant to Amikacin, Gentamicin, Piperacillin, Ceftazidime, Imipenem and Ciprofloxacin. Three bacteria were found to belong to the same type in the RAPD homology analysis.

CONCLUSIONSThere are many kind of multi-drug resistant pathogenic bacteria for nosocomial infection in our burn wards. To control the spread of infection due to above-mentioned 3 bacteria is the focus of nosocomial infection control.

Acinetobacter baumannii ; genetics ; isolation & purification ; Burns ; epidemiology ; microbiology ; Cross Infection ; epidemiology ; microbiology ; Drug Resistance, Multiple, Bacterial ; Genes, Bacterial ; Humans ; Methicillin-Resistant Staphylococcus aureus ; genetics ; isolation & purification ; Microbial Sensitivity Tests ; Molecular Epidemiology ; Pseudomonas aeruginosa ; genetics ; isolation & purification ; Random Amplified Polymorphic DNA Technique ; Sequence Homology