Nosocomial Setting Research Articles

A survey of people with ventriculoperitoneal shunts in the community

Background The most common route for shunting in most countries is now ventriculoperitoneal (VP). Reasons for switching from ventriculoatrial (VA) to VP shunting include the need for more revisions and the greater risk of infection in VA shunts. While in the nosocomial setting healthcare workers are very familiar with shunt problems, this might give a skewed impression of their actual prevalence, and the purposes of this survey were firstly to establish the situation regarding VP shunted people in the community not currently receiving medical attention, and secondly to compare them to those in our previous 2006 survey of people with VA shunts.

Nursing Home–Acquired Pneumonia

Nursing home-acquired pneumonia (NHAP) was first described in 1978. Since then there has been much written regarding NHAP and its management despite the lack of well-designed studies in this patient population. The most characteristic features of patients with NHAP are the atypical presentation, which may lead to delay in diagnosis and therapy. The microbial etiology of pneumonia encompasses a wide spectrum that spans microbes recovered from patients with community-acquired pneumonia to organisms considered specific only to nosocomial settings. Decision to transfer a nursing home patient to an acute care facility depends on a host of factors, which include the level of staffing available at the nursing home, patients' advance directives, and complexity of treatment. The presence of risk factors for multidrug-resistant pathogens dictates approach to therapy. Prevention remains the cornerstone of reducing the incidence of disease. Despite the advance in medical services, mortality from NHAP remains high.

Assessment of high-level gentamicin and glycopeptide-resistant Enterococcus faecalis and E. faecium clonal structure in a Portuguese hospital over a 3-year period

This study focussed on the clonal structure and temporal distribution of E. faecalis and E. faecium with high-level resistance to gentamicin (HLGR) and glycopeptides (GR) collected from clinical samples during 2004 to 2006 at a Portuguese Hospital. The findings were an E. faecalis-dominant and epidemic clone (PFGE-AO), the maintenance of a major epidemic E. faecium clone (PFGE-c) and a high prevalence of putative virulence genes--asa1 (aggregation substances), gelE (gelatinase), cylA (cytolysin), esp (enterococcal surface protein), and hyl (hyaluronidase)--most of them significantly associated with the major clones of both species. The E. faecalis GR isolates ST6 and the E. faecium GR isolates ST17, ST18 and ST280 belong to the clonal complexes E. faecalis-CC2 and E. faecium-CC17, which are well adapted to the nosocomial setting and are disseminated worldwide. This study highlights the need for continuous and active surveillance in this Portuguese hospital in order to follow the evolution of these epidemic and persistent clones.

Antimicrobial resistance pattern of Pseudomonas aeruginosa in clinical isolates from ICU patients

Pseudomonas aeruginosa remains one of the most important pathogens in the nosocomial setting, where it is a common causative agent of bacteremia [1,2]. The aim of this study was to evaluate the antimicrobial resistance of Pseudomonas spp. strains isolated from inpatients hospitalized in the ICU of our hospital throughout a 3-year period.

Inducible clindamycin resistance in Staphylococcus aureus

The resistance to antimicrobial agents among Staphylococci is an increasing problem. The resistance to macrolide can be mediated by msr A gene coding for efflux mechanism or via erm gene encoding for enzymes that confer inducible or constitutive resistance to macrolide, lincosamide and Type B streptogramin. The present study was aimed to find out the percentage of Staphylococcus aureus having inducible clindamycin resistance (iMLS(B)) in our geographic area using D-test. Also, we tried to ascertain the relationship between Methicillin-resistant Staphylococcus aureus (MRSA) and inducible clindamycin resistance, association of these iMLS(B) isolates with community or nosocomial setting and treatment options for these iMLS(B) isolates. A total of 200 non-duplicate Staphylococcus aureus isolates from various clinical samples from both outdoor and indoor patients were studied. Susceptibility to routine antimicrobial agents was carried out using Kirby Bauer method. Methicillin resistance was detected by oxacillin disc on Mueller Hinton agar (MHA) supplemented with 2% NaCl. D-test was performed on all erythromycin-resistant and clindamycin-sensitive Staphylococcus aureus strains to detect inducible clindamycin resistance. Among 200 Staphylococcus aureus strains, 50 (25%) were found to be MRSA and 36 were D-test positive. Also, MRSA isolates showed both higher inducible resistance and constitutive resistance to clindamycin as compared to Methicillin-sensitive Staphylococcus aureus (MSSA). Out of 36 isolates of Staphylococcus aureus showing inducible clindamycin resistance, 24 were from the outpatient department and 12 were recovered from indoor patients. All isolates of Staphylococcus aureus showed 100% sensitivity to vancomycin and linezolid. Clindamycin is kept as a reserve drug and is usually advocated in severe MRSA infections depending upon the antimicrobial susceptibility results. We have reported a higher incidence of iMLS(B) from both community (66.67%) as well as hospital (33.33%) setup. Therefore clinical microbiology laboratory should report inducible clindamycin resistance routinely.

Evaluation of ChromID MRSA for the Detection of Methicillin-resistantStaphylococcus aureus

Background: Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in both nosocomial and community settings, and screening for a carrier is an important infection control practice in many hospitals. We evaluated the sensitivity and specificity of the ChromID MRSA assay (bioMerieux, Marcy I’Etoile, France). Methods: A total of 190 clinical samples were collected from the anterior nares of premature infants in a newborn intensive care unit (N-ICU). Equal volumes (100μL) of the samples were inoculated on mannitol salt agar with oxacillin 6 mg/L (MSAO) and ChromID MRSA after emulsifying the screening swab in brain-heart Infusion broth with oxacillin 6 mg/L (BE). The specimens in BE were subcultured on ChromID MRSA after an overnight incubation. Results: Twenty-one of 190 samples (11%) was positive for MRSA by BE. After a 24 h incubation, the sensitivity/specificity of MSAO was 52%/98% and that of ChromID MRSA was 62%/100%, and at 48 h, the sensitivity/specificity of MSAO was 62%/92% and that of ChromID MRSA was 81%/99%. Conclusion: ChromID MRSA is a useful selective medium for the rapid isolation and identification of MRSA. (Korean J Clin Microbiol 2009;12:169-173)

Increasing prevalence of ESBL-producing Enterobacteriaceae in Europe

Extended-spectrum beta-lactamases (ESBLs) have been increasingly reported in Europe since their first description in 1983. During the 1990s, they were described mainly as members of the TEM- and SHV-beta-lactamase families in Klebsiella pneumoniae causing nosocomial outbreaks. Nowadays, they are mostly found in Escherichia coli that cause community-acquired infections and with increasing frequency contain CTX-M enzymes. Dissemination of specific clones or clonal groups and epidemic plasmids in community and nosocomial settings has been the main reason for the increase in most of the widespread ESBLs belonging to the TEM (TEM-24, TEM-4, TEM-52), SHV (SHV-5, SHV-12) and CTX-M (CTX-M-9, CTX-M-3, CTX-M-14 or CTX-M-15) families in Europe. Co-selection with other resistances, especially to fluoroquinolones, aminoglycosides and sulfonamides, seems to have contributed to the problem. The emergence of epidemic clones harbouring several beta-lactamases simultaneously (ESBLs, metallo-beta-lactamases or cephamycinases) and of new mechanisms of resistance to fluoroquinolones and aminoglycosides warrants future surveillance studies.

Emergence of the vanA genotype among Enterococcus gallinarum isolates colonising the intestinal tract of patients in a university hospital in Rio de Janeiro, Brazil

We describe the characteristics of seven unusual isolates of vancomycin-resistant enterococci (VRE) carrying both the vanC1 and vanA genes that were detected during a 3-month survey carried out to investigate the occurrence of faecal carriage of VRE. The isolates were identified as Enterococcus gallinarum and showed high-level resistance to both vancomycin and teicoplanin (minimum inhibitory concentrations >256 μg/mL and 64–96 μg/mL, respectively). All seven isolates were also resistant to chloramphenicol, erythromycin and high levels of gentamicin, and showed intermediate susceptibility to both quinolones tested (ciprofloxacin and norfloxacin). Susceptibility to fosfomycin, rifampicin and tetracycline varied among isolates. High-level resistance to gentamicin was associated with the aac(6′ )- aph(2″ ) gene, and resistance to erythromycin was associated with the erm(B) gene. The seven vanA-carrying E. gallinarum isolates had similar pulsed-field gel electrophoresis (PFGE) profiles. The emergence of multiple antimicrobial resistance, including high-level resistance to glycopeptides, among E. gallinarum points out the need to increase awareness for detection and proper characterisation of these microorganisms, as they may represent potential reservoirs of transmissible, clinically significant resistance genes in nosocomial settings.

Management of invasive candidiasis and candidemia in adult non-neutropenic intensive care unit patients: Part I. Epidemiology and diagnosis

Invasive candidiasis and candidemia are frequently encountered in the nosocomial setting, particularly in the intensive care unit (ICU). To review the current management of invasive candidiasis and candidemia in non-neutropenic adult ICU patients based on a review of the literature and a European expert panel discussion. Candida albicans remains the most frequently isolated fungal species followed by C. glabrata. The diagnosis of invasive candidiasis involves both clinical and laboratory parameters, but neither of these are specific. One of the main features in diagnosis is the evaluation of risk factor for infection which will identify patients in need of pre-emptive or empiric treatment. Clinical scores were built from those risk factors. Among laboratory diagnosis, a positive blood culture from a normally sterile site provides positive evidence. Surrogate markers have also been proposed like 1,3 beta-D: glucan level, mannans, or PCR testing. Invasive candidiasis and candidemia is a growing concern in the ICU, apart from cases with positive blood cultures or fluid/tissue biopsy, diagnosis is neither sensitive nor specific. The diagnosis remains difficult and is usually based on the evaluation of risk factors.

Management of invasive candidiasis and candidemia in adult non-neutropenic intensive care unit patients: Part II. Treatment

Invasive candidiasis and candidemia are frequently encountered in the nosocomial setting particularly in the intensive care unit (ICU). To review the current management of invasive candidiasis and candidemia in non-neutropenic adult ICU patients based on a review of the literature and an European expert panel discussion. Empiric and directed treatment for invasive candidiasis are predicated on the hemodynamic status of the patient. Unstable patients may benefit from broad-spectrum antifungal agents, which can be narrowed once the patient has stabilized and the identity of the infecting species is established. In stable patients, a more classical approach using fluconazole may be satisfactory provided that the patient is not colonized with fluconazole resistant strains or there has been recent past exposure to an azole (<30 days). In contrast, pre-emptive therapy is based on the presence of surrogate markers.

Prevalence ofagrDysfunction among ColonizingStaphylococcus aureusStrains

Mutations in the staphylococcal virulence regulator gene agr frequently occur during Staphylococcus aureus infection. Whether agr-defective strains are fit for colonization, an important prerequisite for infection, is unknown. Screening by means of assays to detect delta-hemolysin activity and agr autoinducing peptide production indicated that 15 ( approximately 9%) of 160 healthy human subjects were colonized with an agr-defective strain or a mixture of agr-positive and -defective S. aureus strains. The presence of identical agr-defective strains in family members suggests that these strains are transmissible. Additionally, carriage of an agr-defective strain was associated with hospitalization, raising the possibility that such strains may be selected in a nosocomial setting.

Significance of Staphylococcus lugdunensis Bacteremia: Report of 28 Cases and Review of the Literature

Staphylococcus lugdunensis endocarditis has been associated with an aggressive course. The aim of this study was to determine factors associated with the development of endocarditis in patients with S. lugdunensis bacteremia. A retrospective analysis of all patients with S. lugdunensis bacteremia in three tertiary care centers in Switzerland was performed. Data regarding medical history, symptoms, and susceptibility of S. lugdunensis isolates were collected. Our results were reviewed in the context of the current literature. A total of 28 patients with S. lugdunensis bacteremia were identified. Of the 13 patients with endocarditis, all were community acquired. Cardiac surgery was performed in 85% of these patients; mortality was 23%, reflecting the aggressive course of this disease. In contrast, in the 15 patients without endocarditis, no complications associated with S. lugdunensis bacteremia were observed. In 73%, a probable source was identified in the form of a venous catheter or other foreign device. Only three of these episodes were community acquired. No difference was observed in susceptibility of the S. lugdunensis isolates to penicillin, which was 77% in endocarditis isolates, and 87% in isolates of bacteremia without endocarditis, respectively. S. lugdunensis bacteremia is associated with endocarditis in up to 50% of patients. Every patient with community-acquired S. lugdunensis bacteremia should be carefully examined for signs of endocarditis. Once S. lugdunensis endocarditis is diagnosed, close monitoring is essential and surgical treatment should be considered early. In the nosocomial setting, endocarditis is far less frequent, and S. lugdunensis bacteremia is usually associated with a catheter or other foreign materials.

Detection of Pseudomonas aeruginosa producing metallo-β-lactamase VIM-2 in a central hospital from Portugal

Pseudomonas aeruginosa remains one of the most important pathogens in the nosocomial setting [1]. P. aeruginosa exhibits intrinsic resistance to several antimicrobial agents. The antipseudomonal β-lactams represent a major weapon against Pseudomonas infections, either for monotherapy or for combination therapy, for which β-lactams almost invariably represent one of the components. Therefore, resistance to these agents constitutes a major challenge for anti-Pseudomonas chemotherapy. Several mechanisms can contribute to β-lactam resistance in P. aeruginosa, including β-lactamase production, outer membrane impermeability and active efflux mediated by RND-type efflux systems [1]. During the last decade, the metallo-β-lactamases (MBLs) have emerged as new threatening mechanisms of broad-spectrum β-lactam resistance in P. aeruginosa. In fact, these enzymes can efficiently degrade virtually all antipseudomonal β-lactams (except aztreonam), while they are not susceptible to therapeutic β-lactamases inhibitors [2]. Based on amino acid sequence homology, these MBLs have been classified into four major types: IMP, VIM, SPM and GIM. Clinical isolates harbouring the MBLs IMP and VIM have been increasingly reported worldwide, mostly in European and Asian countries [2]. This increase in occurrence, types and rate of dissemination of MBLs makes early detection very critical. The benefits of such treatment include the timely implementation of strict infection control practices, as well as clinical guidance. The aim of this study was to determine the presence of these enzymes in imipenem-resistant P. aeruginosa isolates collected at the Centro Hospitalar of Coimbra (CHC), during a two-year period (April 2003 to April 2005) and to ascertain their clonal relationship. CHC is a cluster formed by a central hospital and several specialised units located at distances of less than 8 km, namely, Hospital dos Covoes (central hospital), Instituto Maternal (maternity hospital) and Hospital Pediatrico (paediatric hospital). The Microbiology Laboratory also analysed samples from another hospital (Hospital de Pombal) located 30 km away. Bacterial identification and minimal inhibitory concentrations (MIC) were performed with the MicroScan WalkAway (Dadebehring) system according to the instructions of the manufacturer and API32GN or API PSE systems (bioMerieux). All intermediate strains were considered as nonsusceptible strains. The MICs of β-lactams were also determined by E-test in isolates that presented the enzyme VIM-2. The results were interpreted on the basis of CLSI recommended breakpoints [3]. The screening of MBLs was done by the double combined disk test [4]. Polymerase chain reaction (PCR) analyses for the detection of MBLs genes (blaIMP, blaVIM, blaGIM and blaSPM-1) were carried out for all strains in which the screening test gave positive results [5]. The amplicons were directly sequenced on both DNA strands on an ABI PRISM 377 automated sequencer. The nucleotide and deduced amino acid sequences were analysed with software available online (http://blast.ncbi.nlm.nih.gov/ Eur J Clin Microbiol Infect Dis (2008) 27:1269–1271 DOI 10.1007/s10096-008-0579-2

Survival of enveloped and non-enveloped viruses on surfaces compared with other micro-organisms and impact of suboptimal disinfectant exposure

Survival of enveloped and non-enveloped viruses was compared with that of bacteria, yeasts and mycobacteria when dried on the surface of polyvinyl chloride test carriers in the presence or absence of an organic matrix. The efficacy of glutaraldehyde and accelerated hydrogen peroxide (AHP) disinfectants was evaluated. Reovirus, a non-enveloped virus, persisted and had a RF of 2 after 30 days whereas Enterococcus faecalis had an RF of 4 over the same time period. The other test organisms (Sindbis virus, Pseudomonas aeruginosa, Mycobacterium chelonae and Candida albicans) had variable survivals but none survived as long as 30 days. Both glutaraldehyde and AHP were effective at manufactures' recommended dilutions for high-level disinfection. However, only 7% AHP eliminated a glutaraldehyde-resistant strain of M. chelonae. Breakthrough survival was detected at 0.1% glutaraldehyde and 0.05% AHP for all organisms tested. Our data emphasise the need for effective cleaning and disinfection in nosocomial settings to prevent pathogen transmission.

In vitro synergism of β-lactams with ciprofloxacin and moxifloxacin against genetically distinct multidrug-resistant isolates of Pseudomonas aeruginosa

In vitro combinations of β-lactams with fluoroquinolones against multidrug-resistant (MDR) Pseudomonas aeruginosa were tested. From a total of 200 isolates, 24 genetically distinct isolates defined by pulsed-field gel electrophoresis (PFGE) were selected. The isolates were exposed over time to imipenem, meropenem and ceftazidime as well as to their combinations with ciprofloxacin and moxifloxacin. All isolates were resistant to all agents tested at concentrations equal to their average serum level. Synergy of any of the tested combinations was found in 10 isolates (41.7%). This was shown after 4 h and 6 h of exposure accompanied by re-growth after 24 h. Not all the tested combinations were active against the same isolates. The combinations of imipenem + ciprofloxacin, ceftazidime + ciprofloxacin and imipenem + moxifloxacin were the most active. When time–kill assays were repeated for the latter isolates at antimicrobial concentrations equal to their maximum serum levels, synergy was prolonged to 24 h. The present findings should be interpreted with caution for the management of infections by MDR P. aeruginosa. They underscore the potential interest of reporting synergism between β-lactams and fluoroquinolones in the nosocomial setting when a MDR isolate emerges.

Type IV SCCmec found in decade old Brazilian MRSA isolates

Methicillin-resistant Staphylococcus aureus (MRSA) commonly causes infection in hospitalized patients. Since its appearance in the 1960s, the SCCmec has evolved throughout the years into 5 different types (I-V), each bearing a different set of genes. Infection with MRSA SCCmec types I, II or III is almost exclusively restricted to hospitalised patients. However, recently, community acquired MRSA (CA-MRSA) infections have been reported with increasing frequency, usually caused by a type IV SCCmec MRSA in nosocomial settings. We studied the prevalence of SCCmec types in 50 nosocomial strains collected from 1995 to 1999. The SCCmec complex type and presence of Panton-Valentine leukocidin (PVL) were determined by PCR. Strains had been previously typed by PFGE and were now typed by MLST. We found that 3 of the isolates studied bore a type IVc SCCmec all having different PFGE and MLST profiles (ST3, ST5 and ST88). All strains bearing a type III SCCmec belonged to MLST ST239 (Brazilian/Iberian clone). Only the strain which presented the ST5 profile bore the pvl gene. The type IVc SCCmec strains presented relatively lower levels of resistance to oxacillin in comparison to the type III SCCmec strains. The pattern of dissemination of the type IV SCCmec remains to be elucidated. The finding of strains carrying a type IV SCCmec in the present study among strains isolated at least 7 years ago indicates that clones bearing a type IV SCCmec have been present in Brazil for quite some time, and must have gone by undetected.

Anti-Infective Treatment of Bacterial Urinary Tract Infections

Bacterial urinary tract infections (UTI) are frequently found in the outpatient as well as in the nosocomial setting. The bacterial UTI can be stratified into uncomplicated and complicated UTI. Antibiotic resistance is continuously increasing in uncomplicated as well as complicated UTI. In uncomplicated UTI efforts are made to use antibiotic substances exclusively for this indication. In complicated UTI as broad spectrum antibiotics are increasingly used, the higher the antimicrobial resistance rates are reported. There are two predominant aims in the antimicrobial treatment of both uncomplicated and complicated UTI: 1.) rapid and effective response to therapy, prevention of complications and prevention of recurrence in the individual patient treated, and 2.) prevention of emergence of resistance to anti-infective agents in the microbial environment. The use of antibiotics has to keep up with the continuous change in antimicrobial resistance and the tailored needs in the individual patient. Antibiotic substances therefore need to become evaluated for each indication and continuously followed for clinical usage. The knowledge of structure-activity relationships of antimicrobial substances and bacterial resistance mechanisms to antibiotics help to use antibiotics better in daily routine and design new derivatives and substances. The aim of this review is to describe the chemistry and structure-activity relationships of current antibiotics and promising substances in development for the treatment of UTI.

“Alert” microrganisms: role of microbiology laboratory

The phenomenom of antibiotic resistance represents today an important problem especially in nosocomial settings with a considerable impact in clinical treatment of infections. We have draft in collaboration with C.I.O. (Comitato infezioni Ospedaliere) and applied in the routine of microbiology laboratory the “Procedura per la gestione dei microrganismi sentinella” (Protocol for the management of “alert microrganisms”). In this study we have investigated the isolation of “alert microrganisms” in our hospital in a period of fifteen months and we have evaluated in time a relative antibiotic resistance.The term “alert microrganisms” is refered to microrganisms with particular antibiotic resistance profiles that are responsible of difficult to treat hospital infections. The study suggests the role of microbiology laboratory in the systematic research of “alert microrganisms” as excellent and economic information source for identify they to level of species and following the antibiotic resistance in time.

Bacterial and Fungal Biofilm Infections

Biofilms are communal structures of microorganisms encased in an exopolymeric coat that form on both natural and abiotic surfaces and have been associated with a variety of persistent infections that respond poorly to conventional antibiotic chemotherapy. Biofilm infections of certain indwelling medical devices by common pathogens such as staphylococci are not only associated with increased morbidity and mortality but are also significant contributors to the emergence and dissemination of antibiotic resistance traits in the nosocomial setting. Current treatment paradigms for biofilm-associated infections of semipermanent indwelling devices typically involve surgical replacement of the device combined with long-term antibiotic therapy and incur high health care costs. This review summarizes the existing data relating to the nature, prevalence, and treatment of biofilm-associated infections and highlights experimental approaches and therapies that are being pursued toward more effective treatments.

Reductions in Workload and Reporting Time by Use of Methicillin-Resistant Staphylococcus aureus Screening with MRSA Select Medium Compared to Mannitol-Salt Medium Supplemented with Oxacillin

Methicillin-resistant Staphylococcus aureus (MRSA) is a significant pathogen in both nosocomial and community settings, and screening for carriers is an important infection control practice in many hospitals. In this retrospective study, we demonstrate that the implementation of an MRSA screening protocol using a selective chromogenic medium (MRSASelect) reduced the workload for this screening test by 63.7% overall and by 12.6% per specimen and reduced the turnaround time for reporting by an average of 1.33 days for all MRSA screening specimens, 1.97 days for MRSA-positive specimens, and 1.3 days for MRSA-negative specimens compared to standard mannitol-salt agar supplemented with 6 mg of oxacillin/liter.