Differential Blood Cultures Research Articles

Protocolo diagnóstico y tratamiento de las bacteriemias relacionadas con dispositivos intravasculares

Catheter-related bacteremias (CRB) are one of the most frequent causes of bacteremia and are potentially avoidable. They can be produced through various mechanisms, such as intraluminal, extraluminal, or infusion fluid contamination. Their microbiology varies and although staphylococci are predominant, enterococci, Candida spp., and gram-negative bacillus (GNB), including multiresistant germs, are also frequent. For their diagnosis, it is fundamental to conduct differential blood cultures to evaluate the differential growth time. Their empirical treatment will depend on the risk factors of infection by GNB or multiresistant bacteria. In short-term catheter bacteremias or bacteremias due to aggressive microorganisms (Staphylococcus aureus, Candida spp., or multiresistant GNB), the catheter must be removed. In CRB due to long-term catheters with less virulent microorganisms in stable patients (for example, coagulase-negative staphylococci), sealing it is an option, though always individualized to each patient.

Infectious complications in home parenteral nutrition: A long-term study with peripherally inserted central catheters, tunneled catheters, and ports.

Home parenteral nutrition (HPN) has become a common therapy, with tunneled central venous catheters (CVCs) being the preferred route of administration. Peripherally inserted central catheters (PICCs) have been used increasingly, but whether they should be preferred over other types of CVCs is still controversial. The aim of this study was to evaluate catheter-related complications of CVC in patients receiving HPN. All patients treated at our center for HPN from 2007 to 2017 were prospectively included. A specialized intravenous therapy team took care of these patients. Catheter-related bloodstream infections (CRBSI) were confirmed with positive, simultaneous, differential blood cultures drawn through the CVC and peripheral vein and then semiquantitative or quantitative culture of the catheter tip. In all, 151 patients received HPN during the 11-y study period. Of these patients, 95 were women (63%) and 55 were men (37%), with a mean age of 58 ±13 y. Twenty-six were non-cancer patients (17%) and the remaining 125 patients had an underlying malignancy (83%). Regarding the CVC, 116 were PICCs, 18 Hickman, and 36 ports. Confirmed CRBSI per catheter-days showed 0.15 episodes per 1000 catheter-days for PICCs, 0.72 for Hickman, and 2.02 for ports. PICCs had less-confirmed CRBSIs per 1000 catheter-days than ports (φ = 0.54, P = 0.005), but no difference between PICCs and Hickman was found (φ = 0.32, P = 0.110). Confirmed episodes of CRBSI (2 versus 13%, χ2 = 6.625, P = 0.036) were more frequent with multilumen catheters. In our setting, single-lumen PICC and Hickman catheters showed low infectious complications.

Role of Peripherally Inserted Central Catheters in Home Parenteral Nutrition

Home parenteral nutrition (HPN) has become a common therapy, with tunneled central venous catheters (CVCs) being preferred for its administration. Peripherally inserted central catheters (PICCs) are not currently recommended for long-term HPN, although evidence to support this statement is scarce. The authors aimed to evaluate the outcomes of HPN, focusing on CVC-related complications. All patients attended at the authors' center for HPN from 2007-2011 were prospectively included. HPN composition aimed at 20-35 kcal/kg/d, 3-6 g/kg/d of glucose, 1.0 g/kg/d of amino acids, and <1 g/kg/d of lipids. HPN was infused in an intermittent schedule, mostly at night. Catheter-related bloodstream infections (CRBSIs) were confirmed with positive semi-quantitative or quantitative culture of the catheter or simultaneous differential blood cultures drawn through the CVC and peripheral vein. Seventy-two patients received HPN, with 79 implanted CVCs (48 PICCs, 10 Hickman, and 21 ports). Mean catheter-days were 129.1 for PICCs, 98.5 for Hickman, and 67.7 for ports (P = .685). When analyzing CRBSIs, ports had 44, Hickman had 20, and PICC had 0 episodes per 1000 catheter-days (P = .078). Only PICCs showed less incidence of CRBSIs vs ports (P = .043). Multivariate logistic regression, correcting by catheter-days, patients' age and sex, underlying disease, and type of catheter, showed that only catheter-days (P = .031) was a predictor for CRBSIs (P = .007, Nagelkerke R= = 0.246). PICCs are similar in terms of catheter-related complications to other CVCs for the administration of HPN, especially for oncology patients with HPN lasting <6 months.

Parenteral nutrition line sepsis: the difficulty in diagnosis

Parenteral nutrition (PN) line sepsis is a common and yet poorly managed complication in hospitalised patients receiving PN. Making a clinical diagnosis is difficult as the clinical picture can be very non-specific and definitions of what constitutes line infection can vary. Once there is clinical suspicion, proving it with microbiological techniques is not an exact science. Traditional techniques have required the removal of the PN line to allow microbiologists to perform analysis of it for infection. This has obvious drawbacks as it is often not easy to replace the line in these patients and the line is often later proven not to be the source of the sepsis. Although the gold-standard technique still requires removal of the line, there has been development in the field of diagnosis line infection while conserving the line. These include intra-luminal brushings of the line, differential blood cultures and simple swabs of the line hub. These techniques are not as sensitive but reduce the problems caused by removing and re-inserting the line in these patients. The definition of PN line sepsis varies between institutions. Rates can be expressed as a true number of cases, or can be expressed correctly as a number of cases per 1000 line days to standardise rates between units of differing sizes. Rates can also be altered if the diagnostic criteria are too strict or too lax. Accurate diagnosis of PN line sepsis remains difficult in modern medical practice.

Catheter-Related Bloodstream Infection.

Central venous catheters are associated with the vast majority of nosocomial, catheter-related bloodstream infections (CR-BSI). Despite identification of multiple effective methods for preventing CR-BSI, it remains an important clinical problem. Catheters coated with anti-infective substances, such as chlorhexidine and silver sulfadiazine or rifampin and minocycline, have shown promising results in recent clinical trials, but confirmatory studies by different investigators are still needed. Concern has also been raised about widespread use of clinically important antibiotics on catheter surfaces, which may promote the development of antibiotic resistance. More accurate and cost-effective methods of diagnosing CR-BSI are desirable. Recent studies have evaluated endoluminal brush sampling and differential blood culture growth rates, which may provide acceptable accuracy without requiring removal of long-dwelling catheters, but the accuracy of these techniques needs to be confirmed in other studies.

Differential quantitative blood cultures in the diagnosis of catheter-related sepsis in intensive care units.

The aim of this prospective study was to compare differential blood cultures and quantitative catheter tip cultures for the diagnosis of catheter-related sepsis. Over a period of 2 years, 283 central venous catheters were inserted in 190 adult patients. Catheters were removed when they were no longer needed or when infection was suspected. Immediately before removal of the central venous catheters, blood cultures were performed, with blood drawn simultaneously from the catheter and the peripheral vein. After removal, quantitative catheter culture was performed according to the Brun-Buisson modified Cleri technique. Fifty-five quantitative catheter cultures were positive. They were classified as contaminated (n = 18), colonized (n = 23), or infected (n = 14). Differential blood cultures correctly identified 13 infections. With a catheter/peripheral cfu ratio of 8, differential blood cultures had a sensitivity of 92.8% and a specificity of 98.8%. When the catheters were removed because of suspected infection, differential blood cultures had a sensitivity of 92.8% and a specificity of 100%. Differential blood culture, a technique that does not necessitate catheter removal, seems effective in the diagnosis of catheter-related sepsis in patients in the intensive care unit.

Diagnosis of Catheter-related Infections

Catheter-related infections (CRI) are a major cause of febrile episodes in hospitalized patients. Additionally, approximately 40% of primary infections in intensive care patients are directly related to central venous catheters. Despite the clinical significance of CRI diagnostic procedures are still under debate. Clinical diagnosis which includes systemic signs of infection and suppuration at the catheter entry site is altogether a rare event. Therefore, most cases are still diagnosed by laboratory methods. Although the semiquantitative roll-plate technique is widely used and frequently regarded as gold standard, the disadvantages of a post-hoc diagnosis are obvious. In-situ techniques which leave the suspected catheter in place include differential blood cultures, skin and hub cultures and a new method of microscopic screening of blood drawn through the inflicted catheter. However, until now the true value of all these methods still lack unanimous acceptance. Further research is necessary to close the gap between clinical expectations and laboratory results.

Otitic complications.

The prechemotherapy era still remains vivid in the memory of the older physicians, particularly the otologists. Acute infections of the ear with mastoiditis and otitic complications were frequent, dreadful, and often tragic in their outcome. The patient suspected of having a complication of a middle-ear infection was examined carefully and repeatedly, both locally in the region of the involved ear and systemically, in order to detect early signs of spread beyond the middle ear. The otologist was skilled in ophthalmoscopy and neurologic diagnosis and utilized this knowledage.¹Diagnostic measures, such as spinal taps, blood cultures,²Ottenberg differential blood cultures, cultures of ear discharge, and x-rays, were extensively used and their clinical implications clearly understood.^3,4Surgery was the accepted method of treatment and when properly performed was a lifesaving measure. The introduction of the sulfonamides in 1935 and the antibiotics in 1942 brought about a dramatic change in

AN OPERATIVE PROCEDURE SUGGESTED FOR SINUS THROMBOSIS

Despite a notable advance in the surgical treatment of sinus thrombosis, a mortality of from 35 to 50 per cent is still commonly reported by otologists. In the past, late operative intervention could be assigned as an important factor accounting for this high death rate. Today, however, this reason is not tenable. Early diagnosis and operation is the rule. Incomplete operative intervention with resulting metastatic invasion, for one reason or another, undoubtedly contributes to the high mortality of sinus thrombosis. Dr. Libman's 1 investigations on blood culture have been of tremendous importance in the knowledge of systemic infections of otitic origin. The recent differential blood culture studies of Dr. Ottenberg 2 have thrown new light on the modus operandi of systemic invasion in sinus thrombosis. A preponderance of bacteria obtained from one internal jugular vein as compared with the other is suggestive of the presence of a