Initiation Of Antimicrobial Therapy Research Articles

Answer to March 2014 Photo Quiz

Answer: Bacteremia caused by Tsukamurella tyrosinosolvens. The isolate was definitively identified as Tsukamurella tyrosinosolvens via DNA sequence analysis of the 16S rRNA gene. Similar to those of aerobic actinomycetes such as Gordonia spp., Rhodococcus spp., and Nocardia spp., cell walls of Tsukamurella spp. contain mycolic acids and allow for a weakly positive reaction upon modified acid-fast staining (1). The longer bacillary form of Tsukamurella spp. potentiates preliminary differentiation from Gordonia spp. (short coryneform bacilli) and Rhodococcus spp. (some coccoid forms) (1). Additional phenotypic delineation of Tsukamurella spp. can be guided with demonstration of growth in lysozyme (also Nocardia spp.) and specialized characterization of mycolic acid and menaquinone chemistry. However, molecular techniques, particularly those centered on gene sequencing, are necessary for definitive identification of aerobic actinomycetes to both the genus and species levels (1). Tsukamurella spp. have been documented to be etiologies of clinical disease, with reports increasing in recent years. Within a 12-year period at a university hospital, Liu et al. (2) rank ordered isolates of T. tyrosinosolvens, Tsukamurella spumae, and Tsukamurella pulmonis in the context of keratitis or catheter-related bloodstream infection. On rare occasions, Tsukamurella paurometabola has also been implicated in clinical disease (1). Specific to T. tyrosinosolvens, a recent report by Karunakaran et al. (3) typified a common clinical presentation. A catheter-related bloodstream infection in a 51-year-old hematology patient was resolved via catheter removal and an imipenem regimen. T. tyrosinosolvens has also been implicated in cerebellar abscess (4) and presentations of respiratory disease (5, 6). The two preceding citations shared an underlying status of immunosuppression, ranging from antecedent lung transplantation to delivery of chemotherapeutic agents by a central venous catheter. The cerebellar abscess presented in an immunocompetent patient with predisposing chronic otitis media that was refractory to penicillin and cephalosporin agents. Antimicrobial susceptibility testing was not performed on this isolate, due to the inconclusive utility of the Clinical and Laboratory Standards Institute standards for testing aerobic actinomycetes other than Nocardia spp. (7). Liu et al. (2), in a limited data set, suggested that T. pulmonis yielded higher MICs for clindamycin, erythromycin, vancomycin, and tetracycline than other Tsukamurella spp. Antimicrobials with lower MICs across multiple species included gentamicin, levofloxacin, and ciprofloxacin. Similar to data reported by Karunakaran et al. (3), our patient defervesced quickly upon removal of the peripherally inserted central catheter (PICC) line and initiation of antimicrobial therapy. The patient was discharged to home on parenteral vancomycin therapy. (See page 711 in this issue [doi:10.1128/JCM.03462-12] for photo quiz case presentation.)

Shigellemia in a post renal transplant patient: a case report and literature review

Shigellemia is a complication of shigellosis that occurs generally in malnourished children. In adults, shigellemia is usually seen in immunocompromised individuals. Here we report the first case of shigellemia in a renal transplant patient from India. The patient had history of diarrhea, which was treated symptomatically. Subsequently, the patient developed high-grade fever and blood culture was positive for Shigella flexneri. Recovery was uneventful after the initiation of antimicrobial therapy. In a country like India with high prevalence of shigellosis, screening for Shigella in the pre-transplant period may minimize the morbidity and prolonged hospital stay associated with the complication of septicemia.

Effect of Introducing Procalcitonin on Antimicrobial Therapy Duration in Patients With Sepsis and/or Pneumonia in the Intensive Care Unit

Utilizing procalcitonin (PCT) levels to limit antimicrobial overuse would be beneficial from a humanistic and economic perspective. To assess whether introducing PCT at a teaching hospital reduced antimicrobial exposure in critically ill patients. Patients wereadmitted to the intensive care unit (ICU) for >72 hours with sepsis and/or pneumonia. PCT levels were drawn on admission to the ICU or with new suspected infection, with at least 1 PCT level being drawn at least 48 hours later. Patients were matched in a 1:1 fashion to historical patients on age, Acute Physiology and Chronic Health Evaluation II (APACHE II) score, gender, and primary diagnosis. The primary outcome was duration of initial antimicrobial exposure defined as days from initiation of antimicrobial therapy to the intentional discontinuation of therapy by the physician. Secondary end points included length of stay, readmission to the hospital, and relapse of infection. There were 50 patients in the PCT group and 50 patients in the historical group. The initial duration of antimicrobials was 10 (±4.9) days compared with 13.3 (±7.2), which was statistically significant (P = .0238). The duration of stay in the hospital (13.5 compared with 17.8 days; P = .0299), readmission to the hospital (9 compared with 17; P = .055), and relapse of infection (3 compared with 11; P = .02) were seen less in the PCT group compared with controls. Introducing PCT levels resulted in a shorter duration of initial antimicrobial therapy and was not associated with adverse treatment outcomes.

Clinical Uncertainties in the Approach to Long Term Care Residents With Possible Urinary Tract Infection

Urinary tract infection (UTI) is arguably the most common infection in the long term care (LTC) setting. Making the diagnosis of UTI and deciding when to initiate treatment with antimicrobial therapy is a challenge to all LTC providers. Widespread prevalence of asymptomatic bacteriuria, lack of an accepted clinical or laboratory gold standard to start antibiotics for UTI, and a high prevalence of cognitive impairment in the LTC population all contribute to this challenge. Several consensus based criteria for diagnosing UTI have been published, though these vary from each other owing to different intended purposes. The McGeer and updated Stone criteria are intended for surveillance and benchmarking purposes. The 2005 Loeb criteria represent minimal criteria for the initiation of antimicrobial therapy. Our review focuses on residents without a urinary catheter. The Loeb criteria should be updated, by inclusion of isolated fever in those with profound cognitive impairment as well as scrotal or prostate swelling tenderness to be consistent with the updated McGeer criteria by Stone etal. Urine testing and antimicrobial therapy should not be ordered in those with isolated nonspecific signs or noninfectious symptoms such as fatigue or delirium. Both cavalier urine testing and unnecessary antimicrobial therapy contribute to direct patient harm as well as the rapidly escalating threat of antimicrobial resistance. Observation and monitoring of residents in whom the diagnosis of UTI is unclear is a best practice that should be implemented. Facilities should consider addressing UTI management as part of their quality assurance and performance improvement process.

Conundrum of contagions causing cold in the old: not everybody's got the fever.

Conundrum of contagions causing cold in the old: not everybody's got the fever.

It's not just the antibiotics, it's the treatment.

The recent study by Bloos and colleagues demonstrates that early initiation of antimicrobial therapy is not associated with improved survival in sepsis. We contend that these findings should not be surprising. This study is yet another part of the growing case against early and aggressive antimicrobial therapy and highlights the important roles resuscitation and source control play in the management of the septic patient. We suggest that, whenever possible, antimicrobial therapy should we withheld until objective evidence of infection has been obtained.

Detection of cord blood hepcidin levels as a biomarker for early-onset neonatal sepsis

Early-onset neonatal sepsis (EONS) continues to be a severe condition associated with a high mortality and morbidity. However, symptoms and laboratory markers of this serious condition are nonspecific and currently there are no available standard tests to provide perfect diagnostic accuracy. An early recognition and initiation of antimicrobial therapy are essential in order to prevent morbidity and mortality. Hepcidin, the key regulator of iron homeostasis, is also an acute-phase reactant, which has a critical role in inflammation and contributes to host defense by interfering with microorganism’s access to iron. Since hepcidin expression is induced by interleukin-6 (IL-6), it also plays role in the innate immune system. Recently, endogenous expression of hepcidin by macrophages and neutrophils in response to bacterial pathogens confirmed its role in innate immunity. The clear link between the hepcidin molecule and innate immunity may be used for the detection of EONS. We hypothesized that an increased level of hepcidin in cord blood may be used as a reliable biological marker of EONS and designed a prospective cohort study to test this hypothesis and collected pilot data. Cord blood samples of all infants born between January 2009 and December 2010 at our university hospital were collected after parental consent and a total of 38 infants were enrolled in the study who fulfilled the sepsis criteria. The range of cord blood hepcidin was found to be significantly increased in newborns with EONS (min–max: 118.1–8400ng/mL). To the best of our knowledge, this is the first study to investigate the pathophysiologic relevance of hepcidin in EONS and demonstrate increased levels of hepcidin in cord blood as an acute-phase reactant in response to sepsis.

Mycobacterium avium-intracellulare pulmonary infection complicated by cutaneous leukocytoclastic vasculitis in a woman with anorexia nervosa

A 53-year-old Caucasian woman with a history of anorexia nervosa developed a bilateral lower extremity rash comprised of palpable red to violaceous, sub-centimeter papular lesions that increased in quantity rapidly. She also noted a 2-month history of non-productive cough. Imaging modalities revealed a thin-walled cavitary lesion in the right lung apex and scattered nodular opacities. Acid fast bacilli (AFB) were found in sputum and subsequently identified by culture as Mycobacterium avium-intracellulare (MAI). Punch biopsies of her skin lesions yielded a histological diagnosis of small-to-medium vessel vasculitis. Stains and cultures for organisms were negative. Her skin lesions resolved quickly after the initiation of antimicrobial therapy for MAI. Hypersensitivity vasculitis associated with an atypical mycobacterial infection is unusual. The postulated underlying mechanism is the deposit of immune complexes and not the bacillus itself. While cutaneous leukocytoclastic vasculitis (CLV) due to MAI is certainly a rare entity, it should be entertained in patients with vasculitic skin lesions and a concomitant pulmonary disease.

Impact of rapid microbial identification directly from positive blood cultures using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry on patient management

AbstractFor septic patients, delaying the initiation of antimicrobial therapy or choosing an inappropriate antibiotic can considerably worsen their prognosis. This study evaluated the impact of rapid microbial identification (RMI) from positive blood cultures on the management of patients with suspected sepsis. During a 6-month period, RMI by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was performed for all new episodes of bacteraemia. For each patient, the infectious disease specialist was contacted and questioned about his therapeutic decisions made based on the Gram staining and the RMI. This information was collected to evaluate the number of RMIs that led to a therapeutic change or to a modification of the patient's general management (e.g. fast removal of infected catheters). During the study period, 277 new episodes of bacteraemia were recorded. In 71.12% of the cases, MALDI-TOF MS resulted in a successful RMI (197/277). For adult and paediatric patients, 13.38% (21/157) and 2.50% (1/40) of the RMIs, respectively, resulted in modification of the treatment regimen, according to the survey. In many other cases, the MALDI-TOF MS was a helpful tool for infectious disease specialists because it confirmed suspected cases of contamination, especially in the paediatric population (15/40 RMIs, 37.50%), or suggested complementary diagnostic testing. This study emphasizes the benefits of RMI from positive blood cultures. Although the use of this technique represents an extra cost for the laboratory, RMI using MALDI-TOF MS has been implemented in our daily practice.

Considerations in the Pharmacologic Treatment and Prevention of Neonatal Sepsis

The management of neonatal sepsis is challenging owing to complex developmental and environmental factors that contribute to inter-individual variability in the pharmacokinetics and pharmacodynamics of many antimicrobial agents. In this review, we describe (i) the changing epidemiology of early- and late-onset neonatal sepsis; (ii) the pharmacologic considerations that influence the safety and efficacy of antibacterials, antifungals, and immunomodulatory adjuvants; and (iii) the recommended dosing regimens for pharmacologic agents commonly used in the treatment and prevention of neonatal sepsis. Neonatal sepsis is marked by high morbidity and mortality, such that prompt initiation of antimicrobial therapy is essential following culture collection. Before culture results are available, combination therapy with ampicillin and an aminoglycoside is recommended. When meningitis is suspected, ampicillin and cefotaxime may be considered. Following identification of the causative organism and in vitro susceptibility testing, antimicrobial therapy may be narrowed to provide targeted coverage. Therapeutic drug monitoring should be considered for neonates receiving vancomycin or aminoglycoside therapies. For neonates with invasive fungal infections, the development of new antifungal agents has significantly improved therapeutic outcomes in recent years. Liposomal amphotericin B has been found to be safe and efficacious in patients with renal impairment or toxicity caused by conventional amphotericin B. Antifungal prophylaxis with fluconazole has also been reported to dramatically reduce rates of neonatal invasive fungal infections and to improve long-term neurodevelopmental outcomes among treated children. Additionally, several large multicenter studies are currently investigating the safety and efficacy of oral lactoferrin as an immunoprophylactic agent for the prevention of neonatal sepsis.

Ethnic Variation in Inflammatory Profile in Tuberculosis

Distinct phylogenetic lineages of Mycobacterium tuberculosis (MTB) cause disease in patients of particular genetic ancestry, and elicit different patterns of cytokine and chemokine secretion when cultured with human macrophages in vitro. Circulating and antigen-stimulated concentrations of these inflammatory mediators might therefore be expected to vary significantly between tuberculosis patients of different ethnic origin. Studies to characterise such variation, and to determine whether it relates to host or bacillary factors, have not been conducted. We therefore compared circulating and antigen-stimulated concentrations of 43 inflammatory mediators and 14 haematological parameters (inflammatory profile) in 45 pulmonary tuberculosis patients of African ancestry vs. 83 patients of Eurasian ancestry in London, UK, and investigated the influence of bacillary and host genotype on these profiles. Despite having similar demographic and clinical characteristics, patients of differing ancestry exhibited distinct inflammatory profiles at presentation: those of African ancestry had lower neutrophil counts, lower serum concentrations of CCL2, CCL11 and vitamin D binding protein (DBP) but higher serum CCL5 concentrations and higher antigen-stimulated IL-1 receptor antagonist and IL-12 secretion. These differences associated with ethnic variation in host DBP genotype, but not with ethnic variation in MTB strain. Ethnic differences in inflammatory profile became more marked following initiation of antimicrobial therapy, and immunological correlates of speed of elimination of MTB from the sputum differed between patients of African vs. Eurasian ancestry. Our study demonstrates a hitherto unappreciated degree of ethnic heterogeneity in inflammatory profile in tuberculosis patients that associates primarily with ethnic variation in host, rather than bacillary, genotype. Candidate immunodiagnostics and immunological biomarkers of response to antimicrobial therapy should be derived and validated in tuberculosis patients of different ethnic origin.

Photo Quiz: An 80-Year-Old Female with Acute Myeloid Leukemia and Induction-Associated Neutropenic Fever

An 80-year-old female presented to Geisinger Medical Center for evaluation of a subacute onset of dyspnea on exertion and was found to have moderate normocytic anemia and mild thrombocytopenia, with the presence of a high percentage of blasts in a peripheral blood smear. She underwent a bone marrow biopsy that showed acute myeloid leukemia. She underwent a transfusion and was discharged home to start induction chemotherapy with a 5-day course of clofarabine. She also received allopurinol, fluconazole, and acyclovir for prophylaxis. During her induction chemotherapy, she developed severe neutropenia and thrombocytopenia associated with fever and malaise that prompted a second hospital admission. At the time of this admission, the patient was hemodynamically stable and found to have moderate mucositis. The remainder of her physical examination was unremarkable, and she was placed on vancomycin, cefepime, and fluconazole. An extensive infectious-disease workup that included two initial sets of blood cultures was initiated, resulting in the isolation of Gram-negative bacilli from two FN anaerobic-blood-culture bottles (bioMerieux, Durham, NC). The hematology service was consulted and initiated therapy with filgrastim and sargramostim to improve her neutropenia. The patient also required transfusions of red blood cells and platelets. Her fever persisted for 10 days, although two additional sets of blood cultures collected 2 days after the initiation of antimicrobial therapy were negative. The patient underwent computed-tomography (CT) scans of her chest, abdomen, and pelvis in an unsuccessful attempt to identify the source of her bacteremia. The causative agent of her bacteremia is shown in Fig. 1. Fig 1 Gram stain of growth from a positive-blood-culture bottle. Magnification, ×1,000 (oil). (For answer and discussion, see page 737 in this issue [doi:10.1128/JCM.01156-12])

Quality of blood culture testing - a survey in intensive care units and microbiological laboratories across four European countries

IntroductionBlood culture (BC) testing before initiation of antimicrobial therapy is recommended as a standard of care in international sepsis guidelines and has been shown to reduce intensive care unit (ICU) stay, antibiotic use, and costs in hospitalized patients. Whereas microbiological laboratory practice has been highly standardized, shortfalls in the preanalytic procedures in the ICU (that is indication, time-to-incubation, blood volume and numbers of BC sets) have a significant effect on the diagnostic yield. The objective of this study was to gain insights into current practices regarding BC testing in intensive care units.MethodsQualitative survey, data collection by 138 semi-structured telephone interviews in four European countries (Italy, UK, France and Germany) between September and November 2009 in 79 clinical microbiology laboratories (LABs) and 59 ICUs.ResultsWhereas BC testing is expected to remain the gold standard for sepsis diagnostics in all countries, there are substantial differences regarding preanalytic procedures. The decision to launch BC testing is carried out by physicians vs. ICU nurses in the UK in 92 vs. 8%, in France in 75 vs. 25%, in Italy in 88 vs. 12% and in Germany in 92 vs. 8%. Physicians vs. nurses collect BCs in the UK in 77 vs. 23%, in France in 0 vs. 100%, in Italy in 6 vs. 94% and in Germany in 54 vs. 46%. The mean time from blood collection to incubation in the UK is 2 h, in France 3 h, in Italy 4 h, but 20 h in German remote LABs (2 h in in-house LABs), due to the large number of remote nonresident microbiological laboratories in Germany. There were major differences between the perception of the quality of BC testing between ICUs and LABs. Among German ICU respondents, 62% reported that they have no problems with BC testing, 15% reported time constraints, 15% cost pressure, and only 8% too long time to incubation. However, the corresponding LABs of these German ICUs reported too many false positive results due to preanalytical contaminations (49%), insufficient numbers of incoming BC sets (47%), long transportation time (41%) or cost pressure (18%).ConclusionsThere are considerable differences in the quality of BC testing across European countries. In Germany, time to incubation is a considerable problem due to the increasing number of remote LABs. This is a major issue of concern to physicians aiming to implement sepsis guidelines in the ICUs.

Non-specific inflammatory parameters in patients with pandemic H1N1 influenza

The measurement of non-specific inflammation parameters, such as erythrocyte sedimentation rate (ESR), fibrinogen, C-reactive protein (CRP) and procalctinon (PCT) are very important tools for diagnosis of infections, as well as for monitoring of treatment response. The aim of this study was to determine the significance of non-specific inflammatory parameters in patients with influenza H1N1 infection. ESR, fibrinogen, CRP and PCT were analyzed in patients with influenza H1N1 infection. The diagnosis of influenza H1N1 was established from the nasopharyngeal swabs using Real Time Polymerase Chain Reaction – (RT PCR) method. Chest X-ray was performed to diagnose pneumonia Sixty-three out of 340 hospitalized patients with influenza had pandemic influenza. Their mean age was 34.60±13.82years. They were referred to hospital 1 to 7 (4.06±2.0) days after onset of symptoms. Of these, 46 had pneumonia, while the majority (41 patients) had interstitial pneumonia, and only five had lobar or segmental pneumonia. Patients with pneumonia had significantly higher levels of CRP and PCT in comparison with those without pneumonia. Patients with lobar pneumonia had significantly higher CRP than those with interstitial pneumonia. However, mean values of PCT between interstitial and lobar pneumonia cases did not differ significantly. Interstitial pneumonia was the most common complication of H1N1 infection among our patients. Non-specific parameters of inflammation, especially CRP and PCT were increased in all pneumonia cases, regardless of the etiology. Monitoring of non-specific inflammatory parameters in patients with H1N1 infection allows recognition of patients with complications, their prompt hospitalization and early initiation of antimicrobial therapy.

S2 Ethnic Variation in Inflammatory Profile in Tuberculosis

Introduction and objectivesMycobacterium tuberculosis (MTB) emerged as a pathogen in Africa and has co-evolved with humans following the migration to Europe and Asia some 70,000 years ago. Distinct phylogenetic lineages...

Persistent Catheter-Related Staphylococcus aureus Bacteremia after Catheter Removal and Initiation of Antimicrobial Therapy

ObjectivesCatheter-related Staphylococcus aureus bacteremia (CRSAB) occasionally persists despite catheter removal and initiation of appropriate antimicrobial therapy. The aim of this study was to determine the incidence, risk factors, and outcomes of persistent CRSAB after catheter removal and initiation of antimicrobial therapy.MethodsConsecutive patients with CRSAB were prospectively included from over a 41-month period. We compared the clinical features, 40 bacterial virulence genes, and outcomes between patients with persistent CRSAB (i.e., bacteremia for >3 days after catheter removal and initiation of appropriate antimicrobial therapy) and non-persistent CRSAB.ResultsAmong the 220 episodes of CRSAB, the catheter was kept in place in 17 (6%) and removed in 203 (94%) cases. In 43 (21%) of the 203 episodes, bacteremia persisted for >3 days after catheter removal and initiation of antimicrobial therapy. Methicillin resistance (Odds ratio [OR], 9.01; 95% confidence interval [CI], 3.05–26.61; P<0.001), non-catheter prosthetic devices (OR, 5.37; 95% CI, 1.62–17.80; P = 0.006), and renal failure (OR, 3.23; 95% CI, 1.48–7.08; P = 0.003) were independently associated with persistent CRSAB. Patients with persistent CRSAB were more like to experience complication than were those with non-persistent CRSAB (72% vs. 15%; P<0.001). Among all episodes due to methicillin-resistant S. aureus, persistent CRSAB isolates were associated with accessory gene regulator (agr) group II (P = .04), but presence of other bacterial virulence genes, distribution of vancomycin minimum inhibitory concentration distribution, and frequency of vancomycin heteroresistance did not differ between the groups.ConclusionsIn patients with CRSAB, bacteremia persisted in 21% of cases despite catheter removal and initiation of antimicrobial therapy. Methicillin resistance, renal failure, and non-catheter prosthetic devices were independent risk factors for persistent CRSAB, which was associated with a higher rate of complications.

Pneumocystis jiroveci pneumonia in immunocompromised patients: Delayed diagnosis and poor outcomes in non-HIV-infected individuals

Pneumocystis jiroveci pneumonia (PJP) is a life-threatening disease in immunocompromised patients. Improved knowledge about the varied characteristics and management in different populations may guide treatment. We evaluated the clinical characteristics, management, and outcomes of patients with PJP diagnosed by nested polymerase chain reaction at a medical center in southern Taiwan from 2008 to 2011. The risk factors of mortality among non-human immunodeficiency virus (HIV)-infected patients were analyzed. During the study period, there were 43 cases of PJP, and the common underlying diseases were HIV infection (23 patients, median CD4 count: 19/μl) and malignancy. The HIV-infected patients had a younger age (36.9 ± 13.7 vs. 50.2 ± 16.2 years, p = 0.006), a lower body mass index (19.9 ± 2.3 vs. 22.0 ± 3.7 kg/m(2), p = 0.035), a longer duration of symptoms before admission (24 ± 29 vs. 7 ± 15 days, p = 0.035), and a lower pneumonia severity index (56 ± 25 vs. 99 ± 35, p < 0.001) than non-HIV-infected patients. A delay between admission and starting antimicrobial therapy for PJP (10 ± 10 days vs. 1 ± 3 days, p = 0.004) and a high crude mortality (12/20, 60% vs. 2/23, 9%, p = 0.001) were noted in non-HIV-infected patients. In the univariate analysis, the risk factors for mortality were a low lymphocyte count (p < 0.05) and shock during hospitalization (p = 0.004). A delay in the initiation of antimicrobial therapy for PJP and severe pneumonia were more common in the non-HIV-infected patients and were most likely related to the poor prognosis. The utilization of sensitive diagnostic tools to facilitate early diagnosis and treatment may improve the clinical outcomes of non-HIV-infected patients with PJP.

Opportunistic Pathogens in Diabetic Foot Lesions

Accurate identification of infection in diabetic foot lesions is essential as the alternative can result in complicated medical and/or surgical interventions. The aim should be the differentiation between colonization and infection to avoid premature initiation of antimicrobial therapy. Diabetic foot ulcers provide a suitable environment for a diversity of microorganisms to first contaminate then subsequently colonize the wound. Infection can occur when a pathogenic factor produced by one or more microorganisms exceeds the capacity of the host immune system causing tissue damage and triggering both local and systemic inflammatory responses. The progression from wound colonization to infection is influenced by various factors including type and depth of the wound, blood supply, immune status of the patient. The quantity of microbial flora and pathogenicity expressed by the microorganisms involved will also have an effect.

Development of conventional and real-time multiplex PCR assays for the detection of nosocomial pathogens

Nosocomial infections are major clinical threats to hospitalised patients and represent an important source of morbidity and mortality. It is necessary to develop rapid detection assays of nosocomial pathogens for better prognosis and initiation of antimicrobial therapy in patients. In this study, we present the development of molecular methods for the detection of six common nosocomial pathogens including Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter spp. Conventional multiplex PCR and SYBR Green based real time PCR assays were performed using genus and species specific primers. Blind testing with 300 clinical samples was also carried out. The two assays were found to be sensitive and specific. Eubacterial PCR assay exhibited positive results for 46 clinical isolates from which 43 samples were detected by real time PCR assay. The sensitivity of the assay is about 93.7% in blind test isolates. The PCR results were reconfirmed using the conventional culture method. This assay has the potential to be a rapid, accurate and highly sensitive molecular diagnostic tool for simultaneous detection of Escherichia coli, Staphylococcus aureus, Streptococcus pneumoniae, Klebsiella pneumoniae, Pseudomonas aeruginosa and Acinetobacter spp. This assay has the potential to detect nosocomial pathogens within 5 to 6 hours, helping to initiate infection control measures and appropriate treatment in paediatric and elderly (old aged) patients, pre-and post surgery patients and organ transplant patients and thus reduces their hospitalization duration.

Risk factors for mortality and impact of broad-spectrum cephalosporin resistance on outcome in bacteraemic intra-abdominal infections caused by Gram-negative bacilli

Although several studies have evaluated the association of antimicrobial resistance and mortality in patients with Gram-negative bacteraemia, little is known regarding the impact of antimicrobial resistance on outcome in patients with intra-abdominal infections caused by Gram-negative bacilli (GNB). This study was performed to evaluate the impact of broad-spectrum cephalosporin resistance on outcome in patients with intra-abdominal infections caused by GNB. Data on 365 patients with bacteraemic intra-abdominal infections caused by GNB were obtained from the database of a nationwide surveillance for bacteraemia, and analyzed. Seventy-one of the 365 patients (19.5%) harboured broad-spectrum cephalosporin-resistant infections. When compared with patients with susceptible infections, the group of patients with resistant infections had a lower treatment success rate at 7 days after the initiation of antimicrobial therapy (73.2% vs 85.0%, p = 0.023). However, the 30-day mortality rate for the resistant group was not significantly higher than for the susceptible group (16.9% vs 10.2%, p = 0.112). Multivariable analysis showed that severe sepsis was the most important risk factor associated with mortality (odds ratio 4.91, 95% confidence interval 2.26-10.63), along with underlying liver disease, nosocomial acquisition, underlying solid tumour, and higher Pitt bacteraemia score (all p < 0.05). Antimicrobial resistance and inappropriate initial antimicrobial therapy were not found to be associated with mortality. Our data suggest that antimicrobial resistance and inappropriate initial antimicrobial therapy may not be significant determinants for the prognosis in intra-abdominal infections caused by GNB, for which drainage or decompression procedures of intra-abdominal sources are often necessary.