Trends in antimicrobial resistance among clinical isolates of enterococci in a Brazilian tertiary hospital: a 4-year study

INTRODUCTION: In the past two decades members of the genus Enterococcus have emerged as important nosocomial pathogens worldwide. This study prospectively analyzed the distribution of species and trends in antimicrobial resistance among clinical isolates of enterococci in a Brazilian tertiary hospital from 2006-2009. METHODS: Enterococcal species were identified by conventional biochemical tests. The antimicrobial susceptibility profile was performed by disk diffusion in accordance with the Clinical and Laboratory Standards Institute (CLSI). A screening test for vancomycin was also performed. Minimal inhibitory concentration (MIC) for vancomycin was determined using the broth dilution method. Molecular assays were used to confirm speciation and genotype of vancomycin-resistant enterococci (VRE). RESULTS: A total of 324 non-repetitive enterococcal isolates were recovered, of which 87% were E. faecalis and 10.8% E. faecium. The incidence of E. faecium per 1,000 admissions increased significantly (p < 0.001) from 0.3 in 2006 to 2.3 in 2009. The VRE rate also increased over time from 2.5% to 15.5% (p < 0.001). All VRE expressed high-level resistance to vancomycin (MIC >256µg/ mL) and harbored vanA genes. The majority (89.5%) of VRE belonged to E. faecium species, which were characteristically resistant to ampicillin and quinolones. Overall, ampicillin resistance rate increased significantly from 2.5% to 21.4% from 2006-2009. Resistance rates for gentamicin, chloramphenicol, tetracycline, and erythromycin significantly decreased over time, although they remained high. Quinolones resistance rates were high and did not change significantly over time. CONCLUSIONS: The data obtained show a significant increasing trend in the incidence of E. faecium resistant to ampicillin and vancomycin.

Nosocomial infection and characterization of extended-spectrum β-lactamases-producing Enterobacteriaceae in Northeast Brazil

INTRODUCTION: Extended spectrum β-lactamases (ESBLs) are enzymes that degrade β-lactam antibiotics and have been reported to be an important cause of nosocomial infection in worldwide. METHODS: During 2009, 659 enterobacteria strains were isolated from different clinical specimens and tested for ESBL production. The disk approximation test, combined disk method and addition of clavulanic acid were used for phenotypic detection of the ESBL-producing strains and PCR for detection of the blaTEM and blaCTX-M genes. RESULTS: Among the isolates, 125 were ESBL producers. The blaCTX-M and blaTEM genes were detected in 90.4% and 75% of the strains, respectively. Most strains were isolated from urine. Klebsiella pneumoniae was the most prevalent organism. Microorganisms presented high resistance to the antibiotics. CONCLUSIONS: These results support the need for extending ESBL detection methods to different pathogens of the Enterobacteriaceae family because these methods are only currently standardized by the CLSI for Escherichia coli, Klebsiella pneumoniae, Klebsiella oxytoca and Proteus mirabilis. Carbapenems were the antibiotic class of choice for the treatment of infections caused by ESBL-producing Enterobacteriaceae.

Human herpesvirus 6: report of emerging pathogen in five patients with HIV/AIDS and review of the literature

The reactivation of human herpesvirus 6 (HHV-6) in patients with AIDS can result in an acute and severe diffuse meningoencephalitis. We describe the epidemiological, clinical and outcome findings of five patients with diagnosis of HIV/AIDS and central nervous system involvement (CNS) due to HHV-6. Fever was present in all the patients. Meningeal compromise, seizures and encephalitis were present in some of the patients. Polymerase chain reaction (PCR) of cerebrospinal fluid (CSF) specimens was positive for HHV-6 in all the patients. HHV-6 should be included among opportunistic and emerging pathogens that involve the CNS in patients with AIDS.

Manipulation of host cell functions by Salmonella: the role of the bacterial effector protein SteA

Salmonella enterica serovars are Gram-negative facultative intracellular bacterial pathogens that infect a wide variety of animals. Salmonella infections are common in humans, causing usually typhoid fever and gastrointestinal diseases. Salmonella enterica serovar Typhimurium (S. Typhimurium), which is a leading cause of human gastroenteritis, has been extensively used to study the molecular pathogenesis of Salmonella, because of the availability of sophisticated genetic tools, and of suitable animal and tissue culture models mimicking different aspects of Salmonella infections.(...)

Genomic and environmental factors influence Wolbachia-Drosophila symbiosis

Intracellular, vertically transmitted bacteria form complex and intimate relationships with their hosts. Wolbachia, maternally transmitted α- proteobacteria, live within the cells of numerous arthropod species. Wolbachia are famous master manipulators of insect reproduction: to favour their own spread they can induce male killing, parthenogenesis or cytoplasmic incompatibility. Wolbachia can also protect various insects from pathogens, which makes them a promising tool for the control of vector-borne diseases. Mosquitoes with Wolbachia have already been released in the wild to eliminate dengue. Yet, how Wolbachia manipulate their hosts remains largely unknown.(...)

Fungemia in a university hospital: an epidemiological approach

INTRODUCTION: Fungemia corresponds to the isolation of fungi in the bloodstream and occurs mostly in immunosuppressed patients. The early diagnosis and treatment of these infections are relevant given the serious threat to the affected patients and possible spread to other organs, often becoming fatal. The growing number of fungemia associated with poor prognosis resulted in this research aiming to diagnose and assess the epidemiological aspects of hematogenous infections by fungi. METHODS: The study included 58 blood samples collected within a 1-year period, from patients at the Hospital das Clinicas, Federal University of Pernambuco, by venipuncture in vacuum tubes. Blood samples were processed for direct examination and culture and identification, conducted by observing the macroscopic and microscopic characteristics, as well as physiological characteristics when necessary. RESULTS: Eight (13.8%) episodes of fungemia were identified, accounting for the total sample, and these pathogens were Candida, Histoplasma, Trichosporon, Cryptococcus, and a dematiaceous fungus. C. albicans was the prevalent species, accounting for 37.5% of the cases. Most affected patients were adult males. There was no predominance for any activity, and the risk of acquired immunodeficiency syndrome was the underlying pathology most often cited. CONCLUSIONS: The isolation of fungi considered as emergent species, such as C. membranifaciens and dematiaceous species, highlights the importance of epidemiological monitoring of cases of fungemia in immunocompromised patients, as the therapy of choice depends on the knowledge of the aethiological agent.

Prevalence of enterotoxin-encoding genes and antimicrobial resistance in coagulase-negative and coagulase-positive Staphylococcus isolates from black pudding

INTRODUCTION: Staphylococcal species are pathogens that are responsible for outbreaks of foodborne diseases. The aim of this study was to investigate the prevalence of enterotoxin-genes and the antimicrobial resistance profile in staphylococcus coagulase-negative (CoNS) and coagulasepositive (CoPS) isolates from black pudding in southern Brazil. METHODS: Two hundred typical and atypical colonies from Baird-Parker agar were inoculated on mannitol salt agar. Eighty-two mannitol-positive staphylococci were submitted to conventional biochemical tests and antimicrobial susceptibility profiling. The presence of coagulase (coa) and enterotoxin (se) genes was investigated by polymerase chain reaction. RESULTS: The isolates were divided into 2 groups: 75.6% (62/82) were CoNS and 24.4% (20/82) were CoPS. The biochemical tests identified 9 species, of which Staphylococcus saprophyticus (37.8%) and Staphylococcus carnosus (15.9%) were the most prevalent. Antimicrobial susceptibility tests showed resistance phenotypes to antibiotics widely administered in humans, such as gentamicin, tetracycline, chloramphenicol, and erythromycin. The coa gene was detected in 19.5% (16/82) of the strains and 4 polymorphic DNA fragments were observed. Five CoNS isolates carrying the coa gene were submitted for 16S rRNA sequencing and 3 showed similarity with CoNS. Forty strains were positive for at least 1 enterotoxin-encoding gene, the genes most frequently detected were sea (28.6%) and seb (27.5%). CONCLUSIONS: The presence of antimicrobial resistant and enterotoxin-encoding genes in staphylococci isolates from black pudding indicated that this fermented food may represent a potential health risk, since staphylococci present in food could cause foodborne diseases or be a possible route for the transfer of antimicrobial resistance to humans.

Prevalence of resistance phenotypes in Staphylococcus aureus and coagulase-negative isolates of venous ulcers of primary healthcare patients

INTRODUCTION: In venous ulcers, the presence of Staphylococcus aureus and coagulase-negative staphylococcus resistance phenotypes can aggravate and limit the choices for treatment. METHODS: Staphylococcus isolated from 69 patients (98 ulcers) between October of 2009 and October of 2010 were tested. The macrolide, lincosamide, streptogramin B (MLS B) group resistance phenotype detection was performed using the D-test. Isolates resistant to cefoxitin and/or oxacillin (disk-diffusion) were subjected to the confirmatory test to detect minimum inhibitory concentration (MIC), using oxacillin strips (E-test®). RESULTS: The prevalence of S. aureus was 83%, and 15% of coagulase-negative staphylococcus (CoNS). In addition were detected 28% of methicillin-resistant Staphylococcus aureus (MRSA) and 47% of methicillin-resistant coagulase-negative staphylococcus (MRCoNS). Among the S. aureus, 69.6% were resistant to erythromycin, 69.6% to clindamycin, 69.6% to gentamicin, and 100% to ciprofloxacin. Considering the MRSA, 74% were highly resistant to oxacillin, MIC ≥ 256µg/mL, and the MLS Bc constitutive resistance predominated in 65.2%. Among the 20 isolates sensitive to clindamycin, 12 presented an inducible MLS B phenotype. Of the MRCoNS, 71.4%were resistant to erythromycin, ciprofloxacin and gentamicin. Considering the isolates positive for β-lactamases, the MIC breakpoint was between 0.5 and 2µg/mL. CONCLUSIONS: The results point to a high occurrence of multi-drug resistant bacteria in venous ulcers in primary healthcare patients, thus evidencing the need for preventive measures to avoid outbreaks caused by multi-drug resistant pathogens, and the importance of healthcare professionals being able to identifying colonized versus infected venous ulcers as an essential criteria to implementing systemic antibacterial therapy.

Antimicrobial use, incidence, etiology and resistance patterns in bacteria causing ventilator-associated pneumonia in a clinical-surgical intensive care unit

INTRODUCTION : Antimicrobial resistance is an increasing threat in hospitalized patients, and inappropriate empirical antimicrobial therapy is known to adversely affect outcomes in ventilator-associated pneumonia (VAP). The aim of this study was to evaluate antimicrobial usage, incidence, etiology, and antimicrobial resistance trends for prominent nosocomial pathogens causing ventilator-associated pneumonia in a clinical-surgical intensive care unit (ICU). METHODS : Gram-negative bacilli and Staphylococcus aureus causing VAP, as well as their antimicrobial resistance patterns and data on consumption (defined daily dose [DDD] per 1,000 patient days) of glycopeptides, extended-spectrum cephalosporins, and carbapenems in the unit were evaluated in two different periods (A and B). RESULTS: Antimicrobial use was high, mainly of broad-spectrum cephalosporins, with a significant increase in the consumption of glycopeptides (p < 0.0001) and carbapenems (p < 0.007) in period B. For Acinetobacter baumannii and members of the Enterobacteriaceae family, 5.27- and 3.06-fold increases in VAPs, respectively, were noted, and a significant increase in resistance rates was found for imipenem-resistant A. baumannii (p = 0.003) and third-generation cephalosporins-resistant Enterobacteriaceae (p = 0.01) isolates in this same period. CONCLUSIONS: Our results suggest that there is a link between antibiotics usage at institutional levels and resistant bacteria. The use of carbapenems was related to the high rate of resistance in A. baumannii and therefore a high consumption of imipenem/meropenem could play a major role in selective pressure exerted by antibiotics in A. baumannii strains.

Impact of the introduction of an automated microbiologic system on the clinical outcomes of bloodstream infections caused by Enterobacteriaceae strains

INTRODUCTION: Enterobacteriaceae strains are a leading cause of bloodstream infections (BSI). The aim of this study is to assess differences in clinical outcomes of patients with BSI caused by Enterobacteriaceae strains before and after introduction of an automated microbiologic system by the microbiology laboratory. METHODS: We conducted a retrospective cohort study aimed to evaluate the impact of the introduction of an automated microbiologic system (Phoenix(tm) automated microbiology system, Becton, Dickinson and Company (BD) - Diagnostic Systems, Sparks, MD, USA) on the outcomes of BSIs caused by Enterobacteriaceae strains. The study was undertaken at Hospital São Paulo, a 750-bed teaching hospital in São Paulo, Brazil. Patients with BSI caused by Enterobacteriaceae strains before the introduction of the automated system were compared with patients with BSI caused by the same pathogens after the introduction of the automated system with regard to treatment adequacy, clinical cure/improvement and 14- and 28-day mortality rates. RESULTS: We evaluated 90 and 106 patients in the non-automated and automated testing periods, respectively. The most prevalent species in both periods were Klebsiella spp. and Proteus spp. Clinical cure/improvement occurred in 70% and 67.9% in non-automated and automated period, respectively (p=0.75). 14-day mortality rates were 22.2% and 30% (p=0.94) and 28-day mortality rates were 24.5% and 40.5% (p= 0.12). There were no significant differences between the two testing periods with regard to treatment adequacy, clinical cure/improvement and 14- and 28-day mortality rates. CONCLUSIONS: Introduction of the BD Phoenix(tm) automated microbiology system did not impact the clinical outcomes of BSIs caused by Enterobacteriaceae strains in our setting.

Active surveillance to determine the impact of methicillin resistance on mortality in patients with bacteremia and influences of the use of antibiotics on the development of MRSA infection

Introduction Methicillin-resistant Staphylococcus aureus (MRSA) is among the most important pathogens of nosocomial infections, mainly in intensive care units (ICUs), and accounts for 40-60% of all healthcare-associated S. aureus infections. We evaluated the incidence of nosocomial infection by S. aureus, identified the risk factors for MRSA infection, and evaluated the effect of resistance to methicillin on mortality in patients. Methods We conducted MRSA surveillance at a university hospital in Brazil from January 1, 2010, to December 31, 2010, and performed a retrospective case-control matched study to evaluate the frequency of subsequent MRSA bacteremia and death among patients. We evaluated and compared the risk factors between patients with MRSA and methicillin-sensitive Staphylococcus aureus (MSSA) infection. Results Sepsis was the most common cause of infection (17.7/1,000 patient-days), followed by surgical site (11.4/1,000 patient-days), pneumonia (4.1/1,000 patient-days), and urinary tract infection (2.4/1,000 patient-days). The significant risk factors were time of hospitalization, use of central vascular catheter (CVC), urinary catheter, nasogastric tube, parenteral nutrition, tracheostomy, mechanical ventilation, and previous antibiotic administration, the latter of which was the only independent risk factor for MRSA infection. Mortality was significantly higher in patients with MRSA. The number of antibiotics tested was not related to increases in the frequency of MRSA/1,000 patient-days. The incidence of mortality attributable to MRSA (bloodstream infection) BSI was 50%. Conclusions Surveillance results showed that the use of high levels of antibiotics was directly related to the development of MRSA infection, and the mortality attributable to MRSA in patients with bacteremia was significant.

Serological cross-reactivity of Trypanosoma cruzi, Ehrlichia canis, Toxoplasma gondii, Neospora caninum and Babesia canis to Leishmania infantum chagasi tests in dogs

Introduction: The aim of this study was to evaluate the serological cross-reactivity between Leishmania sp. and other canine pathogens. Methods: Positive serum samples for Ehrlichia canis, Babesia canis, Toxoplasma gondii, Neospora caninum and Trypanosoma cruzi were tested using three serological methods enzyme linked immunosorbent assay (ELISA), indirect immunofluorescent antibody test (IFAT) and Kalazar Detect™, for canine visceral leishmaniasis. Results: Of the 57 dog samples tested, 24 (42.1%) tested positive using one of the three serological methods: 10/57 (17.5%) for ELISA, 11/57 (19.3%) for IFAT and 3/57 (5.3%) for Kalazar Detect™. Conclusions: Our results demonstrated that the presence of other infectious agents may lead to cross-reactivity on leishmaniasis serological tests.

Nosocomial infections in a neonatal intensive care unit during 16 years: 1997-2012

Introduction Surveillance of nosocomial infections (NIs) is an essential part of quality patient care; however, there are few reports of National Healthcare Safety Network (NHSN) surveillance in neonatal intensive care units (NICUs) and none in developing countries. The purpose of this study was to report the incidence of NIs, causative organisms, and antimicrobial susceptibility patterns in a large cohort of neonates admitted to the NICU during a 16-year period. Methods The patients were followed 5 times per week from birth to discharge or death, and epidemiological surveillance was conducted according to the NHSN. Results From January 1997 to December 2012, 4,615 neonates, representing 62,412 patient-days, were admitted to the NICU. The device-associated infection rates were as follows: 17.3 primary bloodstream infections per 1,000 central line-days and 3.2 pneumonia infections per 1,000 ventilator-days. A total of 1,182 microorganisms were isolated from sterile body site cultures in 902 neonates. Coagulase-negative staphylococci (CoNS) (34.3%) and Staphylococcus aureus (15.6%) were the most common etiologic agents isolated from cultures. The incidences of oxacillin-resistant CoNS and Staphylococcus aureus were 86.4% and 28.3%, respectively. Conclusions The most important NI remains bloodstream infection with staphylococci as the predominant pathogens, observed at much higher rates than those reported in the literature. Multiresistant microorganisms, especially oxacillin-resistant staphylococci and gram-negative bacilli resistant to cephalosporin were frequently found. Furthermore, by promoting strict hygiene measures and meticulous care of the infected infants, the process itself of evaluating the causative organisms was valuable.

Performance of the Vitek 2 system software version 5.03 in the bacterial identification and antimicrobial susceptibility test: evaluation study of clinical and reference strains of Gram-positive cocci

Introduction. The genera Enterococcus, Staphylococcus and Streptococcus are recognized as important Gram-positive human pathogens. The aim of this study was to evaluate the performance of Vitek 2 in identifying Gram-positive cocci and their antimicrobial susceptibilities. Methods. One hundred four isolates were analyzed to determine the accuracy of the automated system for identifying the bacteria and their susceptibility to oxacillin and vancomycin. Results. The system correctly identified 77.9% and 97.1% of the isolates at the species and genus levels, respectively. Additionally, 81.8% of the Vitek 2 results agreed with the known antimicrobial susceptibility profiles. Conclusion. Vitek 2 correctly identified the commonly isolated strains; however, the limitations of the method may lead to ambiguous findings.

Implementation of a zebrafish health program in a research facility : A 4-year retrospective study

In the past two decades, zebrafish (Danio rerio)-based research has contributed to significant scientific advances. Still, husbandry and health programs did not evolve at the same pace, as evidenced by the absence of general guidelines. Health monitoring is essential to animal welfare, to permit animal exchanges across facilities, to contribute to robust experimental results, and for data reproducibility. In this study, we report a health program implemented in a zebrafish research facility to prevent, monitor, and control pathogen, and disease dissemination. This program includes quarantine, routine health screening of sentinels, and nonroutine screenings of retired animals and sick/moribund individuals. An extensive list of clinical signs, lesions, and pathogens was monitored based on: daily observation of fish, necropsy, histology, and bacterial culture. The results indicate that the combined analysis of sentinels with the evaluation of sick/moribund animals enables a comprehensive description not only of pathogen prevalence but also of clinical and histopathologic lesions of resident animals. The establishment of a quarantine program revealed to be effective in the reduction of Pseudoloma neurophilia frequency in the main aquaria room. Finally, characterization of the colony health status based on this multiapproach program shows a low prevalence of lesions and pathogens in the facility.