Outbreak of Multidrug-Resistant Acinetobacter baumannii ST208 Producing OXA-23-Like Carbapenemase in a Children's Hospital in Shanghai, China.

Aims: Acinetobacter baumannii is notorious for acquiring antibiotic resistance and causing nosocomial infections worldwide. This study aimed to investigate the prevalence and molecular characteristics of A. baumannii isolates obtained from inpatients and the intensive care unit (ICU) environment of a pediatric hospital in Shanghai, China. Methods: Between July 2017 and January 2018, a total of 88 A. baumannii isolates, including three obtained from ICU environmental specimens, were characterized by antibiotic susceptibility, multilocus sequence typing, and resistance genes. Results: Carbapenem-resistant A. baumannii (CRAB) isolates, which were resistant to all the antibiotics tested except colistin, accounted for 69.3% (61/88) of all isolates. Three sequence types (STs) were identified among the CRAB isolates, and the predominant clone was ST208 (93.4%, 57/61), which included three environmental isolates and 54 clinical isolates collected from ICU patients. Carbapenem-susceptible isolates, none of which was multidrug resistant (MDR), showed a more diverse genetic background with three known STs and 21 novel STs identified. Intrinsic blaOXA-51-like and blaAmpC were detected in all isolates, while blaOXA-23-like was only detected in all CRAB isolates. ISAba1-blaOXA-23-like, ISAba1-blaOXA-51-like, and ISAba1-blaAmpC were identified in 69.3% (all CRAB isolates), 0%, and 65.9% (58 CRAB isolates) of all isolates, respectively. Conclusions: A nosocomial outbreak of MDR A. baumannii ST208 producing OXA-23-like carbapenemase occurred, highlighting the necessity for strict infection control interventions in the ICU.

Incidence of community-onset extended-spectrum ß-lactamase-producing Escherichia coli and Klebsiella pneumoniae infections: an 11-year population-based study in Denmark.

Background: Data elucidating trends of community-onset extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae infections remain sparse in low prevalence areas. We conducted a population-based study to determine the incidence, temporal trends and co-resistance of community-onset ESBL infections.Methods: We identified all recorded episodes of E. coli and K. pneumoniae bacteraemia and urinary tract infections in adult patients (>15 years) in the North Denmark Region between 2007-2017. Using population-based registries, we obtained information on demographics and place of acquisition, and investigated the standardized incidence rates and temporal trends of community-onset ESBL infections and the associated patterns of co-resistance.Results: A total of 3741 episodes of community-onset ESBL E. coli or K. pneumoniae infections were observed during the study period, with the annual standardized incidence rate increasing from 7.5 to 105 per 100,000 person-years between 2007-2017. The increase was conveyed primarily by a rise in E. coli urinary tract infections shifting from being mainly healthcare-associated to community-acquired. ESBL-producing isolates increased from 0.5 to 4.0% with considerable co-resistance.Conclusion: The proportion of E. coli and K. pneumoniae isolates producing ESBL have increased considerably in the North Denmark Region. The increasing incidence and frequent co-resistance should raise awareness among physicians responsible for empirical antibiotic treatment.

Application of mini-MLST and whole genome sequencing in low diversity hospital extended-spectrum beta-lactamase producing Klebsiella pneumoniae population.

Studying bacterial population diversity is important to understand healthcare associated infections' epidemiology and has a significant impact on dealing with multidrug resistant bacterial outbreaks. We characterised the extended-spectrum beta-lactamase producing K. pneumoniae (ESBLp KPN) population in our hospital using mini-MLST. Then we used whole genome sequencing (WGS) to compare selected isolates belonging to the most prevalent melting types (MelTs) and the colonization/infection pair isolates collected from one patient to study the ESBLp KPN population's genetic diversity. A total of 922 ESBLp KPN isolates collected between 7/2016 and 5/2018 were divided into 38 MelTs using mini-MLST with only 6 MelTs forming 82.8% of all isolates. For WGS, 14 isolates from the most prominent MelTs collected in the monitored period and 10 isolates belonging to the same MelTs collected in our hospital in 2014 were randomly selected. Resistome, virulome and ST were MelT specific and stable over time. A maximum of 23 SNV per core genome and 58 SNV per core and accessory genome were found. To determine the SNV relatedness cut-off values, 22 isolates representing colonization/infection pair samples obtained from 11 different patients were analysed by WGS with a maximum of 22 SNV in the core genome and 40 SNV in the core and accessory genome within pairs. The mini-MLST showed its potential for real-time epidemiology in clinical practice. However, for outbreak evaluation in a low diversity bacterial population, mini-MLST should be combined with more sensitive methods like WGS. Our findings showed there were only minimal differences within the core and accessory genome in the low diversity hospital population and gene based SNV analysis does not have enough discriminatory power to differentiate isolate relatedness. Thus, intergenic regions and mobile elements should be incorporated into the analysis scheme to increase discriminatory power.

Phenotypic and Genotypic Characterization of ESBL-, AmpC-, and Carbapenemase-Producing Klebsiella pneumoniae and Escherichia coli Isolates.

OBJECTIVES: Drug resistance among gram-negative bacteria is a worldwide challenge. Due to the importance of drug-resistant Klebsiella pneumoniae and Escherichia coli strains in hospital-acquired infections, we aimed to determine the phenotypic and genotypic characteristics of ESBL-, AmpC-, and carbapenemase-producing isolates obtained from hospitalized patients in Tehran and Ilam (Iran). MATERIALS AND METHODS: In total, 90 K. pneumoniae isolates and 65 E. coli isolates were collected from various infections. Phenotypic identification of bacterial isolates was performed using standard methods. Phenotypic screening of ESBL, AmpC, and carbapenemase enzymes was carried out. Detection of ESBL, AmpC, and carbapenemase genes was also performed by the PCR method. RESULTS: Phenotypic detection tests showed that 36 (40%) K. pneumoniae and 23 (35.4%) E. coli isolates were ESBL producers. Moreover, 18 (20%) and 6 (9.2%) K. pneumoniae and E. coli isolates were AmpC producers, respectively. Modified Hodge test results indicated that 39 (43.3%) K. pneumoniae and 18 (27.7%) E. coli isolates produced carbapenemase. Molecular tests showed that 40% of K. pneumoniae and 36.9% of E. coli isolates were ESBL positive. AmpC was detected in 24.4 and 13.8% of K. pneumoniae and E. coli isolates. Carbapenemase was detected in 34 (37.8%) K. pneumoniae and 13 (20%) E. coli isolates. -Conclusion: In this study, 3 K. pneumoniae isolates simultaneously carried ESBL, AmpC, and carbapenemase genes. Up-to-date strategies such as combination therapy or utilization of new antimicrobial agents might help to combat such drug-resistant organisms.

Paraoxonases and infectious diseases.

The paraoxonases (PON1, PON2 and PON3) are an enzyme family with a high structural homology. All of them have lactonase activity and degrade lipid peroxides in lipoproteins and cells. As such, they play a role in protection against oxidation and inflammation. Infectious diseases are often associated with oxidative stress and an inflammatory response. Infection and inflammation trigger a cascade of reactions in the host, known as the acute-phase response. This response is associated with dramatic changes in serum proteins and lipoproteins, including a decrease in serum PON1 activity. These alterations have clinical consequences for the infected patient, including an increased risk for cardiovascular diseases, and an impaired protection against the formation of antibiotic-resistant bacterial biofilms. Several studies have investigated the value of serum PON1 measurement as a biomarker of the infection process. Low serum PON1 activities are associated with poor survival in patients with severe sepsis. In addition, preliminary studies suggest that serum PON1 concentration and/or enzyme activity may be useful as markers of acute concomitant infection in patients with an indwelling central venous catheter. Investigating the associations between paraoxonases and infectious diseases is a recent, and productive, line of research.

Instant Typing Is Essential to Detect Transmission of Extended-Spectrum Beta-Lactamase-Producing Klebsiella Species.

BACKGROUND: Infections with multidrug-resistant (MDR) microorganisms are an increasing threat to hospitalized patients. Although rapid typing of MDR microorganisms is required to apply targeted prevention measures, technical barriers often prevent this. We aimed to assess whether extended-spectrum beta-lactamase (ESBL)-producing Klebsiella species are transmitted between patients and whether routine, rapid typing is needed. METHODS: For 43 months, the clonality of all ESBL-producing Klebsiella isolates from patients admitted to Erasmus MC University Medical Center in Rotterdam, the Netherlands was assessed with Raman spectroscopy. A cluster was defined as n ≥ 2 patients who had identical isolates. Primary patients were the first patients in each cluster. Secondary patients were those identified with an isolate clonally related to the isolate of the primary patient. RESULTS: Isolates from 132 patients were analyzed. We identified 17 clusters, with 17 primary and 56 secondary patients. Fifty-nine patients had a unique isolate. Patients (n = 15) in four out of the 17 clusters were epidemiologically related. Ten of these 15 patients developed an infection. CONCLUSIONS: Clonal outbreaks of ESBL-producing Klebsiella species were detected in our hospital. Theoretically, after Raman spectroscopy had detected a cluster of n ≥ 2, six infections in secondary patients could have been prevented. These findings demonstrate that spread of ESBL-producing Klebsiella species occurs, even in a non-outbreak setting, and underscore the need for routine rapid typing of these MDR bacteria.

Dominance of CTX-M-type extended-spectrum ß-lactamase (ESBL)-producing Escherichia coli isolated from patients with community-onset and hospital-onset infection in China.

OBJECTIVE: To investigate CTX-M genotypes among extended-spectrum ß-lactamase-producing Escherichia coli (ESBL-EC) isolated from patients with community-onset and hospital-onset infections in China, their clonality and the distribution of CTX-M variants in different specimens of community-onset and hospital-onset infections. METHODS: ESBL-EC isolates were collected from general hospitals from 2011 to 2012 in China. Broth microdilution method antimicrobial susceptibility testing of 16 antibiotics was performed. Clinical data from community-onset and hospital-onset infections due to ESBL-EC were analyzed. ESBL-encoding genes were amplified by PCR and sequenced, and multilocus sequence typing (MLST) was performed for a random selection of predominant CTX-M type strains identified. RESULTS: A total of 1,168 ESBL-EC isolates were obtained from various clinical specimens, 41.7% of which were responsible for causing community-onset infections. The presence of urinary calculi was higher in community-onset infections, whereas malignancy, cardiovascular and cerebrovascular diseases, dementia, chronic renal disease, diabetes mellitus and surgical treatment were found to have higher proportions in hospital-onset infections. There was no significant difference in trauma between community-onset and hospital-onset infections. 96.2% of the isolates were detected to harbor blaCTX-M genes. blaCTX-M-1 group and blaCTX-M-9 group were detected at 40.7% and 48.7% respectively, and both positive group accounted for 10.6%. blaCTX-M-55 (24.8%) and blaCTX-M-15 (18.2%) were the major genotypes in blaCTX-M-1 group while blaCTX-M-14 (46.8%) was predominant in blaCTX-M-9 group. A comparison of blaCTX-M distribution in different specimens between ESBL-EC causing community-onset and hospital-onset infection showed no significant difference. A total of 229 isolates were tested for MLST. ST131 (14%) was the predominant type. ST648, ST405 and ST1193 were also detected. CONCLUSIONS: Community-onset ESBL-EC has emerged as a common pathogen in China. CTX-M-14 is the most commonly encountered, CTX-M-55 and CTX-M-15 have spread rapidly. ST131 is the predominant clonal group, and the great diversity of CTX-M-producing isolates of E. coli has emerged in China.

Detection of carbapenemase-producing enterobacteriaceae in the baltic countries and st. Petersburg area.

The spread of carbapenemase-producing Enterobacteriaceae is a global problem; however, no exact data on the epidemiology of carbapenemase in the Baltic countries and St. Petersburg area is available. We aimed to evaluate the epidemiology of carbapenemase-producing Escherichia coli and Klebsiella pneumoniae in the Baltic States and St. Petersburg, Russia, and to compare the different methods for carbapenemase detection. From January to May 2012, all K. pneumoniae (n = 1983) and E. coli (n = 7774) clinical isolates from 20 institutions in Estonia, Latvia, Lithuania, and St. Petersburg, Russia were screened for carbapenem susceptibility. The IMP, VIM, GIM, NDM, KPC, and OXA-48 genes were detected using real-time PCR and the ability to hydrolyze ertapenem was determined using MALDI-TOF MS. Seventy-seven strains were found to be carbapenem nonsusceptible. From these, 15 K. pneumoniae strains hydrolyzed ertapenem and carried the bla NDM gene. All of these strains carried integron 1 and most carried integron 3 as well as genes of the CTX-M-1 group. No carbapenemase-producing E. coli or K. pneumoniae strains were found in Estonia, Latvia, or Lithuania; however, NDM-positive K. pneumoniae was present in the hospital in St. Petersburg, Russia. A MALDI-TOF MS-based assay is a suitable and cost-effective method for the initial confirmation of carbapenemase production.

[Epidemiologic diagnostic of nosocomial suppurative-septic infections of Pseudomonas etiology based on intraspecies typing of causative agent].

AIM: Scientific justification of optimization of epidemiologic diagnostic of suppurative-septic infection (SSI) caused by Pseudomonas aeruginosa based on comparability of antibiotic sensitivity and beta-lactamase production. MATERIALS AND METHODS: Intraspecies typing of 37 P. aeruginosa strains isolated during microbiological monitoring of 106 patients and 131 objects of clinical environment of surgical and obstetrician hospitals by using a complex ofphenotypic and molecular-biological methods including determination of sensitivity to antibiotics by serial dilutions method and PCR-diagnostics with determination of TEM, SHV, CTX, OXA, MBL, VIM genes was performed. RESULTS: P. aeruginosa strains combined into groups by isolation location during studies turned out to be heterogeneous by sensitivity to antibiotics and beta-lactamase production that allowed to form subgroups of strains by focality attribute. Isolates recovered from different SSI foci had significant differences in minimal inhibitory concentration (MIC) reaching 1024 times. MIC parameter within subgroups did not exceed 8 - 16 consequent dilutions. CONCLUSION: Use of a complex of phenotypic and molecular-biologic methods of causative agent typing including determination of sensitivity to antibiotics by serial dilutions method and evaluation of beta-lactamase production allowed to establish a mechanism of development of SSI epidemic process caused by P. aeruginosa, detect origins and reservoirs of infection in hospital, modes and factors of transmission and reach maximum justification of epidemiologic control and prophylaxis measures of localization of foci of nosocomial infections of pseudomonas etiology.

AmpC ß-lactamases in nosocomial isolates of Klebsiella pneumoniae from India.

BACKGROUND & OBJECTIVES: AmpC ß-lactamases are clinically significant since these confer resistance to cephalosporins in the oxyimino group, 7-α methoxycephalosporins and are not affected by available ß-lactamase inhibitors. In this study we looked for both extended spectrum ß-lactamases (ESBL) and AmpC ß-lactamases in Klebsiella pneumoniae clinical isolates. METHODS: One hundred consecutive, non-duplicate clinical isolates of K. pneumoniae collected over a period of one year (June 2008 - June 2009) were included in the study. An antibiotic susceptibility method was used with 10 antibiotics for Gram-negative infections which helped in screening for ESBL and AmpC ß-lactamases and also in confirmation of ESBL production. The detection of AmpC ß-lactamases was done based on screening and confirmatory tests. For screening, disc diffusion zones of cefoxitin <18 mm was taken as cefoxitin resistant. All cefoxitin resistant isolates were tested further by AmpC disk test and modified three dimensional test. Multiplex-PCR was performed for screening the presence of plasmid-mediated AmpC genes. RESULTS: Of the 100 isolates of K. pneumoniae studied, 48 were resistant to cefoxitin on screening. AmpC disk test was positive in 32 (32%) isolates. This was also confirmed with modified three dimensional test. Indentation indicating strong AmpC producer was observed in 25 isolates whereas little distortion (weak AmpC) was observed in 7 isolates. ESBL detection was confirmed by a modification of double disk synergy test in 56 isolates. Cefepime was the best cephalosporin in synergy with tazobactam for detecting ESBL production in isolates co-producing AmpC ß-lactamases. The subsets of isolates phenotypically AmpC ß-lactamase positive were subjected to amplification of six different families of AmpC gene using multiplex PCR. The sequence analysis revealed 12 CMY-2 and eight DHA-1 types. INTERPRETATION & CONCLUSIONS: Tazobactam was the best ß-lactamase inhibitor for detecting ESBL in presence of AmpC ß-lactamase as this is a very poor inducer of AmpC gene. Amongst cephalosporins, cefepime was the best cephalosporin in detecting ESBL in presence of AmpC ß-lactamase as it is least hydrolyzed by AmpC enzymes. Cefepime-tazobactam combination disk test would be a simple and best method in detection of ESBLs in Enterobacteriaceae co-producing AmpC ß-lactamase in the routine diagnostic microbiology laboratories.

Metallo beta-lactamase producing pseudomonas species--a major cause of concern among hospital associated urinary tract infection.

Multidrug resistant pseudomonas strains are isolated in high frequency from urinary samples in hospitalised patients. With the occurrence of extended spectrum beta-lactamases (ESBLs) and metallo beta-lactamase (MBL)-producing Pseudomonas aeruginosa being increasingly reported worldwide, this study evaluated the resistance pattern of pseudomonad strains to carbapenam and other antipseudomonal antibiotics isolated from patients with hospital associated urinary tract infections along with clinical usefulness of various MBL screening methods (combined disc diffusion test, E-test and modified Hodge test). Presence of ESBL and AmpC beta-lactamases in the isolates was also determined. Of the 87 isolates, 81 (93.1%) were Pseudomonas aeruginosa, 4 (4.6%) were Pseudomonas putida, 2 (2.3%) were Burkholderia cepacia. Thirty-one isolates (35.6%) were resistant to imipenem and 61% of these 31 isolates, were MBL producers by combined disc diffusion test, while 48% were detected by E-test method. Overall, in 30% and 54% strains, production of AmpC and ESBL respectively was observed.

Heat resistance mediated by a new plasmid encoded Clp ATPase, ClpK, as a possible novel mechanism for nosocomial persistence of Klebsiella pneumoniae.

Klebsiella pneumoniae is an important opportunistic pathogen and a frequent cause of nosocomial infections. We have characterized a K. pneumoniae strain responsible for a series of critical infections in an intensive care unit over a two-year period. The strain was found to be remarkably thermotolerant providing a conceivable explanation of its persistence in the hospital environment. This marked phenotype is mediated by a novel type of Clp ATPase, designated ClpK. The clpK gene is encoded by a conjugative plasmid and we find that the clpK gene alone renders an otherwise sensitive E. coli strain resistant to lethal heat shock. Furthermore, one third of a collection of nosocomial K. pneumoniae isolates carry clpK and exhibit a heat resistant phenotype. The discovery of ClpK as a plasmid encoded factor and its profound impact on thermal stress survival sheds new light on the biological relevance of Clp ATPases in acquired environmental fitness and highlights the challenges of mobile genetic elements in fighting nosocomial infections.

Prevalence and antibiotic resistance pattern of metallo-beta-lactamase-producing Pseudomonas aeruginosa from burn patients--experience of an Indian tertiary care hospital.

The objective of the study is to determine the prevalence of Pseudomonas aeruginosa from burn patients, antibiotic resistance pattern and occurrence of acquired MBL-producing P. aeruginosa among isolates collected from burn patients. In this study, two phenotypic methods were used for the detection of MBL-producing P. aeruginosa: zone enhancement with EDTA-impregnated imipenem and ceftazidime discs, and modified Hodge test. One hundred fifty-four isolates of P. aeruginosa were obtained from July 2007 to July 2008. Infection was increased up to 95% in hospitalized patients for >50 days. Highest infection of 39% was found in patients, who had 41 to 50% of burn area followed by 19% in patients with 31 to 40% of burn area. The most common bacteria isolated were P. aeruginosa (55.0%), followed by Staphylococcus aureus (19.29%) and Klebsiella spp. (11.43%). Sixteen percent isolates of P. aeruginosa were positive for metallo-beta-lactamase production by both methods. Antibiotic resistance pattern of MBL-positive strains showed the highest resistance to ceftazidime (70%) followed by chloramphenicol (68%) and gentamicin (62.5%). Routine detection of MBLs ensuring optimal patient care and careful in vitro testing before antibiotic use may help in the prevention and treatment of burn patients infected with metallo-beta- lactamase-producing P. aeruginosa.

Avaliação fenotípica da enzima Klebsiella pneumoniae carbapenemase (KPC) em Enterobacteriaceae de ambiente hospitalar / Phenotypic research on Klebsiella pneumoniae carbapenemase (KPC) enzyme in Enterobacteriaceae from hospitals

INTRODUÇÃO E OBJETIVO: A resistência bacteriana é problema frequente e importante no ambiente nosocomial. Nesse contexto, várias bactérias apresentam habilidade de desenvolver mecanismos de resistência enzimáticos, destacando-se as Enterobacteriaceae. Nesta família de microrganismos, a produção de Klebsiella pneumoniae carbapenemase (KPC) é um mecanismo emergente, o que justifica sua vigilância constante. MATERIAL E MÉTODO: Este trabalho pesquisou o fenótipo de KPC em 30 isolados clínicos de enterobactérias resistentes a cefalosporinas de terceira geração e sensibilidade diminuída a carbapenem oriundas de dois hospitais (em Porto Alegre e na Grande Porto Alegre, RS). Realizou-se discodifusão com imipenem, meropenem e ertapenem, e 14 cepas com halo < 22 mm para o último antimicrobiano foram submetidas ao teste de Hodge modificado. RESULTADOS: Nenhuma amostra apresentou carbapenemase (Hodge negativo). DISCUSSÃO: Apesar de não ter sido detectada carbapenemase, a resistência aos carbapenens possivelmente pode ser atribuída à presença de betalactamases cromossômicas (AmpC) e/ ou de amplo espectro (ESBL) associada à alteração de permeabilidade nos canais de porina. CONCLUSÃO: Considerando o caráter emergente da KPC, torna-se importante seu rastreamento em isolados de enterobactérias com sensibilidade diminuída ao ertapenem.

INTRODUCTION AND OBJECTIVE: Bacterial resistance is a frequent and important problem in the nosocomial environment. In this context, several bacteria have the ability to develop mechanisms of enzymatic resistance, mainly Enterobacteriaceae. In this family of microorganisms, the production of Klebsiella pneumoniae carbapenemase (KPC) is an emerging mechanism, which should be under constant observation. MATERIAL AND METHOD: This study investigated the phenotype of KPC in 30 clinical isolates of Enterobacteriaceae resistant to third generation cephalosporin and carbapenem from two hospitals (Porto Alegre city and Porto Alegre, RS). It was performed disk diffusion method with imipenem, meropenem and ertapenem. Additionally, 14 strains with halo < 22 mm for the last antimicrobial agent underwent modified Hodge test. RESULTS: No sample showed carbapenemase (Hodge negative). DISCUSSION: Despite the fact there was no carbapenemase, resistance to carbapenems is possibly attributed to the presence of beta-lactamases AmpC and/or ESBL associated with changes in the permeability of porin channels. CONCLUSION: Given the emerging nature of KPC, it is important to trace it in Enterobacteriaceae isolates with decreased susceptibility to ertapenem.

[Spreading and mechanisms of antimicrobial resistance of microorganisms, producing beta-lactamases. Phenotyping of potential AmpC-beta-lactamases producers of Enterobacteriaceae and molecular mechanisms of resistance to beta-lactams of Enterobacter cloacae strains, isolated in cases of nosocomial infections].

Susceptibility of nosocomial potential AmpC-beta-lactamases producers strains (n=128), isolated from patients admitted to 30 medical centers of 15 various regions of Russia has been investigated. The susceptibility testing was performed by the broth microdilution method. The most active antibacterial agents acting to the investigated strains remained carbapenems (imipenem and meropenem). PCR-based detection of beta-lactamase genes (TEM, SHV, CTX) was investigated in 51 E. cloacae strains. Alone or in various combinations TEM type beta-lactamases have been found in 31 (60.8%) isolates, SHV in 22 (43.1%), and CTX--in 22 (43.1%). There were negative results of TEM, SHV, CTX beta-lactamases genotyping in 13 (25.5%) E. cloacae suspect strains.

Dissemination of class I integron in Acinetobacter baumliannii isolated from ventilator-associated pneumonia patients and their environment.

Multidrug resistant Acinetobacter baumannii has become the most common cause of health care-associated infections at Maharaj Nakhon Si Thammarat Hospital, Thailand. The objective of the study was to detect integrons using PCR-based method from 96 A. baumannii isolates from ventilator-associated pneumonia (VAP) patients and their environment. Antibiotic susceptibility was determined using a disk diffusion technique. Forty-six isolates exhibited integrase genes, with only class I and class II integron detected in 43 and 3 A. baumannii isolates, respectively. Twenty-seven of 52 clinical and 19 of 44 environmental isolates were integron-positive. Detection rate of integron-positive A. baumannii isolated from VAP patients increased from 25% to 83% over the 4 month study period. The majority (91%) of integron-positive A. baumannii showed resistance to 6 or more of 11 antibiotics tested and 72% of class I integron-positive isolates were imipenem-resistant. Thus, class I integron-positive A. baumannii had spread among the VAP patients and into hospital environment, the latter acting as reservoirs of potential pathogens possessing drug resistance genes.

Hospital acquired pneumonia with high-risk bacteria is associated with increased pulmonary matrix metalloproteinase activity.

BACKGROUND: Neutrophil products like matrix metalloproteinases (MMP), involved in bacterial defence mechanisms, possibly induce lung damage and are elevated locally during hospital- acquired pneumonia (HAP). In HAP the virulence of bacterial species is known to be different. The aim of this study was to investigate the influence of high-risk bacteria like S. aureus and pseudomonas species on pulmonary MMP concentration in human pneumonia. METHODS: In 37 patients with HAP and 16 controls, MMP-8, MMP-9 and tissue inhibitors of MMP (TIMP) were analysed by ELISA and MMP-9 activity using zymography in bronchoalveolar lavage (BAL). RESULTS: MMP-9 activity in mini-BAL was increased in HAP patients versus controls (149 +/- 41 vs. 34 +/- 11, p < 0.0001). In subgroup analysis, the highest MMP concentrations and activity were seen in patients with high-risk bacteria: patients with high-risk bacteria MMP-9 1168 +/- 266 vs. patients with low-risk bacteria 224 +/- 119 ng/ml p < 0.0001, MMP-9 gelatinolytic activity 325 +/- 106 vs. 67 +/- 14, p < 0.0002. In addition, the MMP-8 and MMP-9 concentration was associated with the state of ventilation and systemic inflammatory marker like CRP. CONCLUSION: Pulmonary MMP concentrations and MMP activity are elevated in patients with HAP. This effect is most pronounced in patients with high-risk bacteria. Artificial ventilation may play an additional role in protease activation.