Hospital-acquired Isolates Research Articles

Surveillance of Antibiotic Resistance among Hospital- and Community-Acquired Toxigenic Clostridium difficile Isolates over 5-Year Period in Kuwait.

Clostridium difficile infection (CDI) is a leading and an important cause of diarrhea in a healthcare setting especially in industrialized countries. Community-associated CDI appears to add to the burden on healthcare setting problems. The aim of the study was to investigate the antimicrobial resistance of healthcare-associated and community-acquired C. difficile infection over 5 years (2008–2012) in Kuwait. A total of 111 hospital-acquired (HA-CD) and 35 community-acquired Clostridium difficile (CA-CD) clinical isolates from stool of patients with diarrhoea were studied. Antimicrobial susceptibility testing of 15 antimicrobial agents against these pathogens was performed using E test method. There was no evidence of resistance to amoxicillin-clavulanic acid, daptomycin, linezolid, piperacillin-tazobactam, teicoplanin and vancomycin by both HA-CD and CA-CD isolates. Metronidazole had excellent activity against CA-CD but there was a 2.9% resistance rate against HA-CD isolates. Ampicillin, clindamycin, levofloxacin and imipenem resistance rates among the HC-CD vs. CA-CD isolates were 100 vs. 47.4%; 43 vs. 47.4%; 100 vs. 100% and 100 vs. 89%, respectively. An unexpected high rifampicin resistance rate of 15.7% emerged amongst the HA-CD isolates. In conclusion, vancomycin resistance amongst the HA-CD and CA-CD isolates was not encountered in this series but few metronidazole resistant hospital isolates were isolated. High resistance rates of ampicillin, clindamycin, levofloxacin, and imipenem resistance were evident among both CA-CD and HA-CD isolates. Rifampicin resistance is emerging among the HA-CD isolates.

Antimicrobial susceptibility and molecular characteristics of methicillin-resistant Staphylococcus aureus in a Japanese secondary care facility.

Methicillin-resistant Staphylococcus aureus (MRSA) is prevalent in Japan, and the Staphylococcus cassette chromosome mec (SCCmec) type II is common among hospital-acquired MRSA isolates. Information pertaining to MRSA characteristics is limited, including SCCmec types, in primary or secondary care facilities. A total of 128 MRSA isolates (90 skin and soft tissue isolates and 38 blood isolates) were collected at a secondary care facility, Kawatana Medical Center, from 2005 to 2011. Antimicrobial susceptibility testing for anti-MRSA antibiotics and molecular testing for SCCmec and virulence genes (tst, sec, etb, lukS/F-PV) were performed. Strains positive for lukS/F-PV were analyzed by multilocus sequence typing and phage open-reading frame typing. SCCmec typing in skin and soft tissue isolates revealed that 65.6% had type IV, 22.2% had type II, 8.9% had type I, and 3.3% had type III. In blood isolates, 50.0% had type IV, 47.4% had type II, and 2.6% had type III. Minimum inhibitory concentrations, MIC(50)/MIC(90), against vancomycin, teicoplanin, linezolid, and arbekacin increased slightly in SCCmec II isolates from skin and soft tissue. MICs against daptomycin were similar between sites of isolation. SCCmec type II isolates possess tst and sec genes at a greater frequently than SCCmec type IV isolates. Four lukS/F-PV-positive isolates were divided into two clonal patterns and USA300 was not included. In conclusion, SCCmec type IV was dominant in blood, skin, and soft tissue isolates in a secondary care facility in Japan. Because antimicrobial susceptibility varies with the SCCmec type, SCCmec typing of clinical isolates should be monitored in primary or secondary care facilities.

Antimicrobial Susceptibilities of Aerobic and Facultative Gram-Negative Bacilli from Intra-abdominal Infections in Patients from Seven Regions in China in 2012 and 2013.

To evaluate the antimicrobial susceptibility of Gram-negative bacilli that caused hospital-acquired and community-acquired intra-abdominal infections (IAIs) in China between 2012 and 2013, we determined the susceptibilities to 12 antimicrobials and the extended-spectrum β-lactamase (ESBL) statuses of 3,540 IAI isolates from seven geographic areas in China in a central laboratory using CLSI broth microdilution and interpretive standards. Most infections were caused by Escherichia coli (46.3%) and Klebsiella pneumoniae (19.7%). Rates of ESBL-producing E. coli (P = 0.031), K. pneumoniae (P = 0.017), and Proteus mirabilis (P = 0.004) were higher in hospital-acquired IAIs than in community-acquired IAIs. Susceptibilities of enterobacteriaceae to ertapenem, amikacin, piperacillin-tazobactam, and imipenem were 71.3% to 100%, 81.3% to 100%, 64.7% to 100%, and 83.1% to 100%, respectively, but imipenem was ineffective against P. mirabilis (<20%). Although most ESBL-positive hospital-acquired isolates were resistant to third- and fourth-generation cephalosporins, the majority were susceptible to cefoxitin (47.9% to 83.9%). Susceptibilities of ESBL-positive isolates to ampicillin-sulbactam (<10%) were low, whereas susceptibilities to ciprofloxacin (0% to 54.6%) and levofloxacin (0% to 63.6%) varied substantially. The prevalences of cephalosporin-susceptible E. coli and K. pneumoniae were higher in the northeastern and southern regions than in the central and eastern regions, reflecting the ESBL-positive rates in these areas, and were lowest in the Jiangsu-Zhejiang (Jiang-Zhe) area where the rates of carbapenem resistance were also highest. Ertapenem, amikacin, piperacillin-tazobactam, and imipenem are the most efficacious antibiotics for treating IAIs in China, especially those caused by E. coli or K. pneumoniae. Resistance to cephalosporins and carbapenems is more common in the Jiang-Zhe area than in other regions in China.

Community- versus healthcare-acquired bloodstream infections at Groote Schuur Hospital, Cape Town, South Africa.

Bloodstream infections (BSIs) cause considerable morbidity and mortality. The epidemiology of bacterial infections differs in community and hospital settings. Regular surveillance and reporting of pathogens and antimicrobial susceptibility can assist in appropriate management of BSIs. To describe the distribution of organisms and of antibiotic susceptibility among isolates from blood cultures at a tertiary academic hospital during a 1-year period, stratifying by place of infection acquisition. This was a retrospective descriptive study of bloodstream isolates from cultures from adults (&gt;13 years of age) routinely submitted between 1 October 2011 and 30 September 2012 to the clinical laboratory at Groote Schuur Hospital, Cape Town, South Africa. Community-acquired infections were compared with healthcare-acquired infections, defined as infections developing at least 48 hours after admission or within 3 months of admission to a healthcare facility. Frequencies and proportions of infecting organisms are presented, along with susceptibility results for selected pathogens. The hospital-acquired isolates were stratified by ward (emergency, general medical or general surgical ward or intensive care unit (ICU)) to determine organism frequency and susceptibility patterns by hospital ward. Among adults, 740 non-duplicate pathogens were isolated from BSIs. Nearly three-quarters of infections were healthcare acquired. Enterobacteriaceae and non-fermentative Gram-negative bacilli were predominant among healthcare-acquired pathogens (39.2% and 28.5%, respectively), while Enterobacteriaceae and Gram-positive organisms were the most common among community-acquired pathogens (39.2% and 54.3%, respectively). The majority of community-acquired Enterobacteriaceae were highly susceptible to antibiotics (gentamicin 95.6%, ceftriaxone 96.1% and ciprofloxacin 92.2%), whereas 64.6% of healthcare-associated isolates were susceptible to gentamicin, 58.5% to ceftriaxone and 70% to ciprofloxacin. All community-acquired Staphylococcus aureus isolates v. 52.4% of healthcare-acquired isolates were susceptible to cloxacillin. The susceptibility of healthcare-acquired Pseudomonas aeruginosa and Acinetobacter baumanii complex isolates was &lt;80% to all antibiotics with the exception of colistin. Klebsiella spp., S. aureus and Escherichia coli were the commonest causes of healthcare-acquired infections in all areas outside of the ICUs, whereas Acinetobacter was common in the ICUs and rare in all other areas. The distinction between community- and healthcare-acquired infections is critical in antibiotic selection because narrow-spectrum agents can be utilised for community-acquired infections. The considerable antibiotic resistance of healthcare-acquired pathogens highlights the importance of infection prevention and control. This type of surveillance could be incorporated into routine laboratory practice.

Expression of Panton-Valentine Leukocidin mRNA among Staphylococcus aureus Isolates Associates with Specific Clinical Presentations

Panton-Valentine leukocidin (PVL; gene designation lukF/S-PV) is likely an important virulence factor for Staphylococcus aureus (S. aureus), as qualitative expression of the protein correlates with severity for specific clinical presentations, including skin and soft tissue infections (SSTIs). Development of genetic approaches for risk-assessment of patients with S. aureus infections may prove clinically useful, and whether lukF/S-PV gene expression correlates with specific clinical presentations for S. aureus has been largely unexplored. In the present study, we quantified lukS-PV mRNA among 96 S. aureus isolates to determine whether expression levels correlated with specific clinical presentations in adults and children. Expression level of lukS-PV mRNA among isolates from skin and soft tissue infections (SSTIs) was significantly greater than among isolates from blood stream infection (BSIs), and expression level of lukS-PV mRNA among BSI isolates from children was significantly greater than for BSI isolates among adults. Moreover, expression level of lukS-PV mRNA among community-acquired (CA) isolates was significantly greater than for hospital-acquired (HA) isolates. These data justify additional studies to determine the potential clinical utility for lukS-PV mRNA quantification as a predictive tool for severity of S. aureus infection.

Investigation of the Presence of Panton-Valentine Leukocidin and Clonal Relationship of Community- and Hospital-Acquired Clinical Isolates of Staphylococcus aureus

Staphylococcus aureus is one of the most important pathogens that cause community- and hospital-acquired infections by its toxins and enzymes. Panton-Valentine leukocidin (PVL), a cytotoxin which is especially produced by community-acquired S.aureus strains that cause soft tissue and skin infections and pneumonia. PVL leads to the destruction on polymorphonuclear cells by necrosis or induce apoptosis, so that it has great importance in the virulence of the organism. PVL can also exacerbate the clinical course of S.aureus infections and may lead to severe complications. Studies show that community-acquired PVL-positive S.aureus strains have become prevalent in hospital environments. In this study, we aimed to investigate the presence of PVL from hospital- and community-acquired S.aureus strains and to determine the clonal relationship between the PVL-positive strains. A total of 265 S.aureus strains isolated from different clinical samples (wound, blood, tracheal aspirate, urine, drainage, catheter, parasynthesis fluid) of which 88 were community-acquired and 177 were hospital-acquired according to the CDC criteria were included in the study. Methicillin resistance of the strains were investigated by conventional methods, the presence of PVL and mecA gene regions by polymerase chain reaction, and clonal relationship among the PVL positive S.aureus strains by pulsed-field gel electrophoresis (PFGE). Community-acquired 12.5% (11/88) and hospital-acquired 43% (76/177) of the strains were found resistant to methicillin. Community-acquired (CA) strains were most commonly isolated from wound samples (86%), while 34% of hospital-acquired (HA) strains were isolated from wound, and 33% were from blood samples. The rate of PVL positivity among CA- and HA-strains were found as 15% and 3%, respectively. Hospital-acquired PVL-positive strains were isolated from the samples originating from pediatric (n= 1) and neurology inpatient clinics and intensive care unit (n= 3). Thirty nine percent of PVL-positive CA-S.aureus strains were isolated from samples originated from internal medicine, 23% from general surgery, 15% from dermatology, 15% from orthopedic surgery and 8% from pediatrics outpatient clinics. Ninety two percent of PVL-positive CA-S.aureus strains have been isolated from wound samples, while 67% of HA-S.aureus strains from wound and 33% from blood samples. Five PVL-positive HA- methicillin-sensitive S.aureus strains were found clonally-related with each other by PFGE. When the macrorestriction patterns were evaluated according to Tenover criteria; three of those isolates were indistinguishable, and two were clonally unrelated. There was no clonal relationship between community-acquired strains. In conclusion we observed that PVL could be detected not only in community-acquired strains but also in hospital-acquired strains. The spread of PVL-positive strains in the hospital environment and even create epidemics, increases the risk of mortality and morbidity. Epidemiological studies will help us to understand the clonal spread of CA and HA-S.aureus strains.

The expression of Panton-Valentine leukocidin gene and its correlation with agrA among different clinical isolates of Staphylococcus aureus

Objective To investigate the correlation between expression of Panton-Valentine leukocidin gene and accessory gene regulator among different clinical isolates of Staphylococcus aureus. Methods All non-duplicate Staphylococcus aureus clinical isolates were isolated from various clinical specimens of the patients at 4 hospitals from January 2003 to December 2010.Panton-Valentine leukocidin genes among Staphy lococcus aureus clinical isolates were detected by PCR and DNA sequencing.The expressions of lukS-PV and agr A were determined by real-time PCR. Results Nintysix S.aureus isolates including 58 hospital-acquired and 28 community-acquired isolates were positive for PVL genes,among which 54 from blood,33 from pus and 9 from sputum.Ten isolates cannot be classified due to lack of information.Sixty-seven and 29 PVL-positive isolates were isolated from the specimens of adults and children.The median relative quantities of luk SmRNA of the isolates from pus and blood were 1.500 and 0.818.The quantity of lukSmRNA among the isolates from pus was significantly higher than that from blood (U=634,P=0.025).The median relative quantities of luk SmRNA of the isolates from children and adults were 1.292 and 0.540,respectively.The quantity of lukSmRNA among the isolates from children was significantly higher than that from adults (U=660,P=0.013).The median relative quantities of lukSmRNA among community-acquired and hospital-acquired isolates were 1.034 and 0.536,respectively.The quantity of lukSmRNA among community-acquired isolates was significantly higher than that from hospital-acquired isolates (U=338,P=0.012).The correlation coefficients between lukSmRNA and agr Am RNA of total isolates,pus isolates and blood isolates were 0.592 (P<0.01),0.810 (P<0.01) and 0.543 (P<0.01),respectively.While the correlation coefficients of those among the isolates from children and adults were 0.804 (P<0.01) and 0.476 (P<0.01).The correlation coefficients of those among the isolates from community-acquired and hospital-acquired isolates were 0.767 (P<0.01) and 0.556 (P<0.01). Conclusions The quantity of lukSmRNA of Staphylococcus aureus isolates from pus was significantly higher than that from blood.The agr may have positive regulation effect on the expression of lukS/F-PV,especially among the isolates from pus and children.(Chin J Lab Med,2013,36:313-317) Key words: Staphylococcus aureus; Bacterial toxins; Exotoxins; Leukocidins; Bacterial proteins

Decreasing incidence of Staphylococcus aureus bacteremia over 9 years: Greatest decline in community-associated methicillin-susceptible and hospital-acquired methicillin-resistant isolates

The impact of community-associated methicillin-resistant Staphylococcus aureus (CA-MRSA) emergence on the epidemiology of S aureus bacteremia (SAB) is not well documented. This was an observational study of adult (aged ≥18 years) inpatients with SAB in a single 808-bed teaching hospital during 2002-2003, 2005-2006, 2008-2009, and 2010 with period-stratified SAB rate, onset mode, patient characteristics, and outcome. We encountered a total of 1,098 cases over the entire study period. The rate decreased steadily over time (from 6.64/10(3) discharges in 2002-2003 to 6.49/10(3) in 2005-2006, 5.24/10(3) in 2008-2009, and 5.00/10(3) in 2010; P= .0001), with a greater decline in community-associated cases (0.99/10(3), 0.77/10(3), 0.58/10(3), and 0.40/10(3), respectively; P= .0005) compared with health care-associated cases (5.65/10(3), 5.72/10(3), 4.66/10(3), and 4.60/10(3), respectively; P= .005). The decline was principally in MSSA (3.11/10(3), 2.21/10(3), 2.24/10(3), and 1.75/10(3), respectively; P= .00006), including both community-associated (P=.0002) and health care-associated cases (P= .006). Although overall rate changes in MRSA were not significant (P= .09), hospital-onset MRSA decreased markedly (P < .00001), whereas CA-MRSA increased (P= .03). The all-cause 100-day mortality rate did not change significantly (25.6% for 2002-2003, 25.2% for 2005-2006, 28.1% for 2008-2009, and 32.2% for 2010; P= .10). Differences in MSSA/MRSA-associated mortality decreased (20.1% vs 30.6%, P= .03 for 2002-2003; 18.1% vs 28.9%, P= .05 for 2005-2006; 21.7% vs 32.9%, P= .05 for 2008-2009; and 29.3% vs 34.9, P= .5 for 2010). SAB incidence is decreasing, with the greatest decline in community-associated MSSA and hospital-onset MRSA cases. Most health care-associated cases currently are community-onset. MRSA/MSSA-related mortality is comparable. These changes are likely related to the emergence of CA-MRSA and the inpatient-to-outpatient shift in health care.

Multidrug-resistant North American pulsotype 2 Clostridium difficile was the predominant toxigenic hospital-acquired strain in the province of Manitoba, Canada, in 2006–2007

The objective of the current study was to determine whether the antimicrobial susceptibility profile or genotype of hospital-acquired isolates of Clostridium difficile differed from isolates causing community-acquired disease. Five hundred diarrhoeal stool samples (one >2 ml sample per patient) from patients across Manitoba, Canada, in 2006-2007 that were reported as C. difficile toxin positive were cultured, resulting in 432 isolates of toxin-positive C. difficile for analysis. Of these 432 isolates, acquisition status could be determined for 235 (54.4%); 182 (77.4%) isolates were hospital acquired and 53 (22.6%) were community acquired. North American pulsotype (NAP) designations based on SmaI PFGE could be defined for 52.3% of the 432 isolates, with NAP2 (n=122) being the most common. Ninety-one per cent (71/78) of NAP2 isolates were recovered from patients with hospital-acquired C. difficile disease. Other NAP types and isolates with non-NAP-type PFGE patterns were less frequently associated with hospital-acquired disease. Community-acquired disease (35.3% of isolates) was associated with a wide variety of NAP types. NAP2 isolates were homogeneous (85.5% had SmaI PFGE pattern 0003) and demonstrated low susceptibility to moxifloxacin (6.6%) and clindamycin (1.6%) compared with non-NAP2 isolates (64.1-93.2% moxifloxacin susceptible; 14.1-28.2% clindamycin susceptible). All isolates of C. difficile in Manitoba were susceptible to metronidazole, piperacillin-tazobactam, amoxicillin-clavulanate and meropenem. NAP2 isolates of toxigenic C. difficile were approximately three times more common than NAP1 isolates (28.2 vs 9.1%) in Manitoba in 2006-2007, and these isolates demonstrated high levels of clonality and multidrug resistance, and were associated with hospital acquisition.

Molecular Epidemiology of Methicillin-Resistant Staphylococcus aureus in Israel: Dissemination of Global Clones and Unique Features

From 2006 to 2009, 315 clinical methicillin-resistant Staphylococcus aureus (MRSA) isolates were collected from 5 hospitals across Israel. Most isolates (64%) were related to the global clones spa types t001-SCCmec-I (SCCmec-I stands for staphylococcal cassette chromosome mec type I) (n = 99; 31%), t002-SCCmec-II (n = 82; 26%), and t008-SCCmec-IV (n = 21; 7%), five of which were identified as MRSA strain USA-300. Seventeen strains unique to Israel were identified. SCCmec types IV and V were common among hospital-acquired isolates.

Antimicrobial susceptibilities of urinary extended-spectrum beta-lactamase-producing Escherichia coli and Klebsiella pneumoniae to fosfomycin and nitrofurantoin in a teaching hospital in Taiwan

Urinary tract infections (UTIs) caused by extended-spectrum β-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae have become clinical problems because of limited therapeutic options. The role of fosfomycin in the era of growing bacteria resistance has been widely discussed recently. In this study, we aimed to know the local antimicrobial susceptibilities, fosfomycin susceptibility in particular, of urinary ESBL-producing E coli and K pneumoniae isolates in Taiwan. We collected 200 urine isolates, including 134 ESBL-producing E coli (ESBL-EC) and 66 ESBL-producing K pneumoniae (ESBL-KP) isolates from July 2008 to December 2009 in a university-affiliated teaching hospital in Taiwan. We used disk diffusion method to determine susceptibility to fosfomycin. Fosfomycin may have lower susceptibility when using disk diffusion method compared with agar dilution method. Broth microdilution test was also used to determine minimal inhibitory concentrations (MICs) and susceptibilities to other antimicrobial agents. Imipenem was active against ESBL-EC and ESBL-KP. Fosfomycin had good susceptibility to ESBL-EC (95.5%), including in hospital-acquired isolates, but lower antimicrobial activity against ESBL-KP (57.6%). Trimethoprim-sulfamethoxazole had the highest resistance rate to ESBL-EC and ESBL-KP. Comparing with non-hospital-acquired isolates, hospital-acquired ESBL-KP was associated with significantly lower susceptibility of gentamicin (13.3% vs. 66.7%), trimethoprim-sulfamethoxazole (8.9% vs. 38.1%), ciprofloxacin (26.7% vs. 61.9%), and amikacin (46.1% vs. 81.0%) (p<0.05). The resistance of some strains to ciprofloxacin was significantly associated with lower susceptibilities of gentamicin (32.6% in ESBL-EC), nitrofurantoin (2.4% in ESBL-KP) and trimethoprim-sulfamethoxazole (9.8% in ESBL-KP) (p<0.05) but not accompanied with decreasing susceptibility of fosfomycin. Fosfomycin had the excellent activity against ESBL-EC but not ESBL-KP in this study. Based on the study findings, we suggest that fosfomycin can be a therapeutic option for UTIs with ESBL-EC. Nitrofuranoin was actively against ESBL-EC. Nitrofurantoin may be an alternative option for uncomplicated UTIs with ESBL-EC in Taiwan.

Microbiological and molecular characterization of nosocomial and community Staphylococcus aureus isolates

This study aimed to evaluate the incidence of Staphylococcus aureus infections in different departments of Belcolle Hospital in Viterbo and the surrounding area between January 2003 and June 2008. Isolates of methicillin-resistant S. aureus (MRSA) recovered in this time interval were characterized by microbiological and molecular methods to evaluate the reliability of simple criteria to distinguish between hospital-acquired and community-acquired isolates. MRSA accounted for 33% of all S. aureus, with a significantly higher prevalence in isolates from nosocomial infections. MRSA isolates were assayed by PCR for the presence of 13 genes associated with virulence, agr type and SCCmec type. Cumulative data were analysed by partial least square discriminant analysis and a clear correlation was demonstrated between genetic profiles and classification of isolates as hospital or community acquired according to simple temporal criteria. Nosocomial MRSA isolates from blood samples showed significantly higher genetic diversity than other nosocomial isolates. Our data confirm the existence of significant differences between community- and hospital-acquired MRSA isolates.

Occurrence and Molecular Characteristics of Methicillin-Resistant Staphylococcus aureus and Methicillin-Resistant Staphylococcus pseudintermedius in an Academic Veterinary Hospital

Recently, methicillin-resistant Staphylococcus aureus (MRSA) and methicillin-resistant Staphylococcus pseudintermedius (MRSP) have been increasingly isolated from veterinarians and companion animals. With a view to preventing the spread of MRSA and MRSP, we evaluated the occurrence and molecular characteristics of each in a veterinary college. MRSA and MRSP were isolated from nasal samples from veterinarians, staff members, and veterinary students affiliated with a veterinary hospital. Using stepwise logistic regression, we identified two factors associated with MRSA carriage: (i) contact with an identified animal MRSA case (odds ratio [OR], 6.9; 95% confidence interval [95% CI], 2.2 to 21.6) and (ii) being an employee (OR, 6.2; 95% CI, 2.0 to 19.4). The majority of MRSA isolates obtained from individuals affiliated with the veterinary hospital and dog patients harbored spa type t002 and a type II staphylococcal cassette chromosome mec (SCCmec), similar to the hospital-acquired MRSA isolates in Japan. MRSA isolates harboring spa type t008 and a type IV SCCmec were obtained from one veterinarian on three different sampling occasions and also from dog patients. MRSA carriers can also be a source of MRSA infection in animals. The majority of MRSP isolates (85.2%) carried hybrid SCCmec type II-III, and almost all the remaining MRSP isolates (11.1%) carried SCCmec type V. MRSA and MRSP were also isolated from environmental samples collected from the veterinary hospital (5.1% and 6.4%, respectively). The application of certain disinfection procedures is important for the prevention of nosocomial infection, and MRSA and MRSP infection control strategies should be adopted in veterinary medical practice.

Antibiotic susceptibility of intra-abdominal infection isolates from Indian hospitals during 2008

A total of 542 clinical isolates of aerobic Gram-negative bacilli from intra-abdominal infections were collected during 2008 from seven hospitals in India participating in the Study for Monitoring Antimicrobial Resistance Trends (SMART). Isolates were from various infection sources, the most common being gall bladder (30.1 %) and peritoneal fluid (31.5 %), and were mostly hospital-associated isolates (70.8 %) as compared to community-acquired (26.9 %). The most frequently isolated pathogens were Escherichia coli (62.7 %), Klebsiella pneumoniae (16.7 %) and Pseudomonas aeruginosa (5.3 %). Extended-spectrum beta-lactamase (ESBL) rates in E. coli and K. pneumoniae were very high, at 67 % and 55 %, respectively. Most isolates exhibited resistance to one or more antibiotics. The most active drugs were generally ertapenem, imipenem and amikacin. However, hospital-acquired isolates in general, as well as ESBL-positive isolates, exhibited lower susceptibilities than community-acquired isolates. Further surveillance monitoring of intra-abdominal isolates from India is recommended.

Characterization of Extended-Spectrum β-Lactamases Produced byEscherichia coliIsolated from Hospitalized and Nonhospitalized Patients: Emergence of CTX-M-15-Producing Strains Causing Urinary Tract Infections

Extended-spectrum beta-lactamase (ESBL)-producing Escherichia coli isolates were obtained from hospitalized and nonhospitalized patients in Belgium between August 2006 and November 2007. The antimicrobial susceptibility of these isolates was determined and their ESBL genes were characterized. Clonal relationships between the CTX-M-producing E. coli isolates causing urinary tract infections were also studied. A total of 90 hospital- and 45 community-acquired cephalosporin-resistant E. coli isolates were obtained. Tetracycline, enrofloxacine, gentamicin, and trimethoprim-sulfamethaxozole resistance rates were significantly different between the community-onset and hospital-acquired isolates. A high diversity of different ESBLs was observed among the hospital-acquired E. coli isolates, whereas CTX-M-15 was dominating among the community-acquired E. coli isolates (n = 28). Thirteen different pulsed-field gel electrophoresis profiles were observed in the community-acquired CTX-M-15-producing E. coli, indicating that multiple clones have acquired the bla(CTX-M-15) gene. All community-acquired CTX-M-15-producing E. coli isolates of phylogroups B2 and D were assigned to the sequence type ST131. The hospital-acquired CTX-M-15-producing E. coli isolates of phylogroups B2, B1, A, and D corresponded to ST131, ST617, ST48, and ST405, respectively. In conclusion, CTX-M-type ESBLs have emerged as the predominant class of ESBLs produced by E. coli isolates in the hospital and community in Belgium. Of particular concern is the predominant presence of the CTX-M-15 enzyme in ST131 community-acquired E. coli.

Molecular genetic characterization of methicillin-resistant Staphylococcus aureus isolates recovered from Moscow clinics

Methicillin-resistant Staphylococcus aureus (MRSA) is the causative agent of nosocomial infections observed worldwide. The goal of this work was to study the genetic variations in MRSA isolates recovered from Moscow clinics and compare various methods of molecular typing (multiplex PCR, SNP genotyping based on the determination of single-nucleotide polymorphisms). A total of 62 epidemiologically unrelated hospital-acquired MRSA isolates were studied. A previously described multiplex PCR assay was utilized for the molecular typing of staphylococcal cassette chromosome mec (SCCmec). SNP genotyping that targets the seven sequences in five housekeeping genes (arcC162, arcC210, aroE132, gmk123, tpi241, tpi243, and yqiL333) was employed. Primer extension was used to screen single nucleotide variants followed by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). Multilocus sequence typing (MLST) was used as a reference assay. Most MRSA isolates (93.6%) were assigned to the clonal complex (CC) 8 disseminated worldwide. Three MRSA isolates (4.8%) proved to belong to CC1. The following correlation was established in this study between SCCmec cassette types and sequence types (STs): ST8-MRSA carried SCCmec type IV and ST239-MRSA carried type-III a SCCmec. Four SNP groups associated with certain SCCmec types were also identified. The developed SNP genotyping assay aided by MALDI-MS enables the rapid genotyping of S. aureus isolates according to their clonal types.

Population-Level Interventions to Reduce the Development and Transmission of Community-Associated Antimicrobial Resistance: A Perspective from the National Collaborating Centre for Infectious Diseases

Antimicrobial resistance (AMR) in bacteria is the end result of a multitude of factors. Some of the key factors beyond innate resistance include antimicrobial selective pressure (1–5), acquisition of a foreign genetic resistance element(s) (1–5), clonal dissemination (1) and new mutations (2,3,5); factors vary for different species and geographical locations. Increased global antimicrobial use is the foremost reason for the spread of AMR in the community setting (1). Social networks of individuals (households, schools and child care facilities) have served both as a reservoir for these bacteria and as a common route for their transmission. Similarly, hospitals, nursing homes and long-term care facilities have also served as reservoirs for antibiotic-resistant organisms, and the discharge of patients from these facilities contributes to the spread of resistance within communities. In addition, the use of antimicrobials in food animals has been an important contributing cause (1).

Variable-Number Tandem Repeat Analysis and Multilocus Sequence Typing Data Confirm the Epidemiological Changes Observed with Staphylococcus aureus Strains Isolated from Bloodstream Infections

Since 2000, our geographical region in France systematically surveys bloodstream infections (BSI) due to Staphylococcus aureus. This survey involves 39 health care institutions (HCIs) encompassing 6,888 short-stay beds and was performed during two 3-month periods during 2007 and 2008. The study periods of this survey identified 292 S. aureus isolates causing BSI. Extensive molecular characterization, including genotyping as well as toxin, agr, and staphylococcal cassette chromosome content determinations, allowed us to describe epidemiological evolution in comparison to that discussed in our previous study. Our main epidemiological observation shows that the incidence of BSI remained constant but that methicillin (meticillin)-resistant S. aureus strains with a wider variety of genetic backgrounds now harbor pyl, as has already been reported in different European countries. We noticed stable numbers of BSI episodes involving community-acquired methicillin-sensitive S. aureus (MSSA), whereas a drastic increase in the number of strains harboring the tst gene was recorded. The increase in the number of tst gene-harboring strains is related to known hospital-acquired MSSA isolates and appears related to epidemic episodes in specific HCIs. Monitoring the increase in prevalence of specific strains helps us understand where the standard precautions are not satisfactorily applied or do not efficiently prevent the spread of epidemic MSSA strains in these HCIs. The recent increases in incidence of these strains call for particular vigilance to avoid the spread of potentially virulent MSSA strains harboring the tst gene and for continuance of this strategy of BSI surveillance.

The battle against multi-resistant strains: Renaissance of antimicrobial essential oils as a promising force to fight hospital-acquired infections

Hospital-acquired infections and antibiotic-resistant bacteria continue to be major health concerns worldwide. Particularly problematic is methicillin-resistant Staphylococcus aureus (MRSA) and its ability to cause severe soft tissue, bone or implant infections. First used by the Australian Aborigines, Tea tree oil and Eucalyptus oil (and several other essential oils) have each demonstrated promising efficacy against several bacteria and have been used clinically against multi-resistant strains. Several common and hospital-acquired bacterial and yeast isolates (6 Staphylococcus strains including MRSA, 4 Streptococcus strains and 3 Candida strains including Candida krusei) were tested for their susceptibility for Eucalyptus, Tea tree, Thyme white, Lavender, Lemon, Lemongrass, Cinnamon, Grapefruit, Clove Bud, Sandalwood, Peppermint, Kunzea and Sage oil with the agar diffusion test. Olive oil, Paraffin oil, Ethanol (70%), Povidone iodine, Chlorhexidine and hydrogen peroxide (H(2)O(2)) served as controls. Large prevailing effective zones of inhibition were observed for Thyme white, Lemon, Lemongrass and Cinnamon oil. The other oils also showed considerable efficacy. Remarkably, almost all tested oils demonstrated efficacy against hospital-acquired isolates and reference strains, whereas Olive and Paraffin oil from the control group produced no inhibition. As proven in vitro, essential oils represent a cheap and effective antiseptic topical treatment option even for antibiotic-resistant strains as MRSA and antimycotic-resistant Candida species.

Countrywide molecular survey of methicillin-resistant Staphylococcus aureus strains in Poland.

The present investigation was undertaken to assess the proportion of methicillin-resistant Staphylococcus aureus (MRSA) strains among hospital-acquired isolates and to determine the clones of MRSA currently circulating in Poland by using a number of molecular techniques. Between January and May 2005, methicillin resistance was investigated among a total of 915 S. aureus isolates collected from 39 hospitals. A total of 208 (22.7%) isolates were positive for the mecA gene by PCR. The molecular characterization of MRSA isolates was carried out by the multiple-locus variable-number tandem repeat fingerprinting, pulsed-field gel electrophoresis, multilocus sequence typing, and staphylococcal chromosomal cassette mec (SCCmec) typing methods. The Hungarian (PFGE B; ST239, SCCmec type III [ST239-III]), Iberian (ST247-I), and Berlin (ST45-IV) clones were predominant, representing approximately 52.9, 11.5, and 10.0% of the MRSA isolates, respectively. A decline in the proportion of earlier MRSA clones, such as ST5-IV (a Pediatric clone), ST80-IV) (a Mediterranean clone), ST239-III (a Polish and Brazilian clone), and ST30-IV (a southwest Pacific clone) was observed. Additionally, the emergence of an MRSA clone with SCCmec type V, possibly representing a community-acquired strain, was observed in two hospitals during this study.