Antibacterial properties of lidocaine

Amphiphilic Chitosan Porous Membranes as Potential Therapeutic Systems with Analgesic Effect for Burn Care

Eliminating or at least lessening the pain is a crucial aspect of burns management, as pain can negatively affect mental health and quality of life, and it can also induce a delay on wound healing. In this context, new amphiphilic chitosan 3D porous membranes were developed and investigated as burns therapeutic systems with analgesic effect for delivery of lidocaine as local anesthetic. The highly porous morphology of the membranes and the structural modifications were evidenced by scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and infrared spectroscopy (FTIR). Improved compression mechanical properties, long-term hydrolytic degradation (28 days) evaluation and high swelling capacities (ranging from 8 to 22.6 g/g) indicate an increased capacity of the prepared membranes to absorb physiological fluids (burns exudate). Lidocaine in vitro release efficiency was favored by the decreased content of cross-linking agent (reaching maximum value of 95.24%) and the kinetic data modeling, indicating that lidocaine release occurs by quasi-Fickian diffusion. In addition to the in vitro evaluation of analgesic effect, lidocaine-loaded chitosan membranes were successfully investigated and proved antibacterial activity against most common pathogens in burns infections: Staphylococcus aureus and Methicillin-resistant Staphylococcus aureus.

International Society for Heart and Lung Transplantation consensus statement for the standardization of bronchoalveolar lavage in lung transplantation

Bronchoalveolar lavage (BAL) is a key clinical and research tool in lung transplantation (LTx). However, BAL collection and processing are not standardized across LTx centers. This International Society for Heart and Lung Transplantation-supported consensus document on BAL standardization aims to clarify definitions and propose common approaches to improve clinical and research practice standards. The following 9 areas are covered: (1) bronchoscopy procedure and BAL collection, (2) sample handling, (3) sample processing for microbiology, (4) cytology, (5) research, (6) microbiome, (7) sample inventory/tracking, (8) donor bronchoscopy, and (9) pediatric considerations. This consensus document aims to harmonize clinical and research practices for BAL collection and processing in LTx. The overarching goal is to enhance standardization and multicenter collaboration within the international LTx community and enable improvement and development of new BAL-based diagnostics.

Antimicrobial effects of local anaesthetics

After the introduction of cocaine to the medical practice, local anaesthetics (LA) became essential in pain control. LA infiltration along the incision may be used to provide surgical anaesthesia or postoperative analgesia. This study aimed to compare the antimicrobial effects of the topical antimicrobial agent mupirocine with those of the LA lidocaine and the combination of lidocaine and adrenalin. In our study, the in vitro antimicrobial effects of 1 mL sterile saline, 20 mg/mL mupirocine, 20 mg/mL Lidocaine, and 20 mg/mL Lidocaine and Adrenaline were tested against Staphylococcus aureus American type culture collection (ATCC) 29213, Pseudomonas aeruginosa ATCC 27853, and Escherichia coli ATCC 25922 as Group C (Control), Group M (Mupirocine), Group L (Lidocaine), and Group LA (Lidocaine + adrenaline), respectively. S aureus ATCC 29213, P aeruginosa ATCC 27853, and E coli ATCC 25922 were cultured onto Mueller-Hinton agar (Oxoid, UK) plates for 18 to 24 hours at 37°C. Colonies from these plates were suspended in sterile saline and a 0.5 McFarland turbidity standard suspension (corresponding to 1.5 × 10⁸  CFU/mL) of each isolate was prepared. S Aureus ATCC 29213 inhibition zone diameter values of Group M, Group LA, and Group L were significantly higher compared with the group C (P ˂ 0.05). P aeruginosa ATCC 27853 inhibition zone diameter values of Group M and Group LA were significantly higher compared with the group C (P ˂ 0.05). E coli ATCC 25922 inhibition zone diameter values of Group M, Group LA, and Group L were significantly higher compared to the group C (P ˂ 0.05). LA infiltration along the incision may be used to provide surgical anaesthesia or postoperative analgesia. Considering that LAs show antimicrobial effects besides their analgesic effects, they may contribute to preventing the development and reducing the rate of surgical infections, decreasing the requirement to administer antibiotics. However, caution should be exercised not to antagonise the effective treatment of surgical infections, remembering that controversy on the antimicrobial effects of LAs remains in the literature. Therefore, further comprehensive studies with larger patient populations are warranted to demonstrate the antimicrobial effects of LAs.

A review and new insights to antimicrobial action of local anesthetics

Local anesthetics (LAs) are medications which can provide analgesia in distinct body regions through the blockade of voltage-gated sodium channels. Besides pain management, the supplemental role of LAs as antimicrobial agents has been documented in several studies. Different databases including PubMed, Scopus, and Web of Science with the name of different local anesthetics and related names for antimicrobial keywords were searched without time limitation. This review summarized different in vitro and in vivo studies regarding antimicrobial effects of different LAs with focuses on antimicrobial applications of most studied LAs, interaction with different agents which combined with LAs, and mechanisms of action and structural dependence of LAs antibacterial effects. Among different LAs, lidocaine is the most studied preparation. Reduction of the incidence of endophthalmitis after intravitreal injection, prophylaxis for surgical wound infections, prevention of the incidence of catheter-associated infections, oral biofilm reduction on the buccal mucosa, and prevention against bacteria that produced nosocomial infection are some examples of lidocaine antimicrobial application. Studies showed that different factors including structure, concentration, duration of exposure, type of microorganism tested, and temperature affect the degree of LA antimicrobial activity. In addition, various agents such as antibiotics, preservatives, opioids, epinephrine, and propofol can combine with LAs and affect their antimicrobial properties through synergistic or antagonistic action. Due to antibacterial activities, LAs could be applied in a clinic for prophylaxis of surgical site infection. In the application of LAs prior to diagnostic procedures caution should be needed; otherwise, when culturing the specimen, they could lead to false negative results.

Does Use of Lidocaine Affect Culture of Synovial Fluid Obtained to Diagnose Periprosthetic Joint Infection (PJI)? An In Vitro Study

Background

Synovial fluid culture (SFC) is recommended as one of the major diagnostic criteria by the Musculoskeletal Infection Society (MSIS) for diagnosing periprosthetic joint infection (PJI). Local anesthetic agents are used for anesthesia and analgesia in some clinical settings to relieve pain. As a local anesthetic, lidocaine is safely used in arthrocentesis to obtain synovial fluid. The goal of this study was to determine if infiltration anesthesia with additive-free lidocaine 2% has antibacterial effects that might interfere with subsequent SFC.

Material/Methods

Eight isolates of reference strains of Staphylococcus aureus, Staphylococcus epidermidis, Staphylococcus hominis, Escherichia coli, Klebsiella pneumoniae, Acinetobacter baumannii, Streptococcus pyogenes, and Candida albicans were incubated on the plates. Each bacterial suspension was formed by 50-fold dilution before the test lidocaine 2% was added. For each strain, bacterial suspension was divided into 2 groups (5 samples each) exposed either lidocaine 2% or sterile non-bacteriostatic 0.45% saline. The antimicrobial property of lidocaine 2% was determined by measuring the bacterial density on agar plates incubated for 24 h and comparing it with controls unexposed to lidocaine 2%.

Results

Exposure to lidocaine 2% negatively affected microbial viability in vitro. Of the lidocaine 2% exposure, reference strains but no Streptococcus pyogenes strain resulted in fewer colony-forming units compared with the sterile saline control. The antibacterial property of lidocaine 2% appears to affect the ability to culture the organism in synovial fluid.

Conclusions

Lidocaine 2% has strong antimicrobial activities against some commonly encountered bacterial strains in PJI. As a result, infiltration anesthesia with additive-free lidocaine 2% before the arthrocentesis procedure may affect the results of SFC. To further evaluate its potential antibacterial usefulness in clinical applications, studies are needed to assess the ability of lidocaine to reduce the risk of iatrogenic infections.

Evaluation of histomorphometric changes in tissue architecture due to fixation delay

Introduction:

All good tissue specimen preparations require complete fixation. The process of tissue handling and processing from patient to paraffin block is too frequently invisible to the pathologists. Many times due to certain emergencies or unavailability of a proper fixative, tissues are kept in different carrying media such as normal saline (NS) or local anesthetic till the availability of a proper fixative solution. This fixation delay can lead to various tissue architectural changes which can affect its diagnostic value.

Aims:

The aim of this study was to assess sectioning ability, staining intensity and microscopic details of tissues kept in different carrying media at different time intervals followed by standard fixation.

Materials and Methods:

Fresh tissue specimen, i.e., goat tongue was collected and its middle portion was retained and was used for study purpose. The tissue was grossed and kept in various carrying media for five different time intervals. Standard formaldehyde fixation was then carried out followed by sectioning and staining. The sections were evaluated histologically under light microscope.

Statistical Analysis:

For sectioning parameter, Fisher's exact test and for staining and microscopic details, Mann–Whitney U-test was used.

Results:

According to the study, NS is considered as a best carrying media followed by 10% honey and local anesthetic. Two percent hydrogen peroxide cannot be used as a carrying media.

Conclusion:

It was concluded that NS should be given first preference as a carrying media till the availability of a suitable fixative. Clinicians and Pathologists should have to familiarize themselves with the advantages and disadvantages of using various carrying media and the histomorphometric changes associated with delayed fixation which may lead to incorrect diagnosis.

Pharmacological and Combined Interventions to Reduce Vaccine Injection Pain in Children and Adults: Systematic Review and Meta-Analysis

BACKGROUND

This systematic review assessed the effectiveness and safety of pharmacotherapy and combined interventions for reducing vaccine injection pain in individuals across the lifespan.

DESIGN/METHODS

Electronic databases were searched for relevant randomized and quasi-randomized controlled trials. Self-reported pain and fear as well as observer-rated distress were critically important outcomes. Data were combined using standardized mean difference (SMD) or relative risk with 95% confidence intervals (CI).

RESULTS

Fifty-five studies that examined breastfeeding (which combines sweet-tasting solution, holding, and sucking), topical anesthetics, sweet-tasting solutions (sucrose, glucose), vapocoolants, oral analgesics, and combination of 2 versus 1 intervention were included. The following results report findings of analyses of critical outcomes with the largest number of participants. Compared with control, acute distress was lower for infants breastfed: (1) during vaccination (n=792): SMD -1.78 (CI, -2.35, -1.22) and (2) before vaccination (n=100): SMD -1.43 (CI, -2.14, -0.72). Compared with control/placebo, topical anesthetics showed benefit on acute distress in children (n=1424): SMD -0.91 (CI, -1.36, -0.47) and self-reported pain in adults (n=60): SMD -0.85 (CI, -1.38, -0.32). Acute and recovery distress was lower for children who received sucrose (n=2071): SMD -0.76 (CI, -1.19, -0.34) or glucose (n=818): SMD -0.69 (CI, -1.03, -0.35) compared with placebo/no treatment. Vapocoolants reduced acute pain in adults [(n=185), SMD -0.78 (CI, -1.08, -0.48)] but not children. Evidence from other needle procedures showed no benefit of acetaminophen or ibuprofen. The administration of topical anesthetics before and breastfeeding during vaccine injections showed mixed results when compared with topical anesthetics alone. There were no additive benefits of combining glucose and non-nutritive sucking (pacifier) compared with glucose or non-nutritive sucking (pacifier) alone or breastfeeding and sucrose compared with breastfeeding or sucrose alone.

CONCLUSIONS

Breastfeeding, topical anesthetics, sweet-tasting solutions, and combination of topical anesthetics and breastfeeding demonstrated evidence of benefit for reducing vaccine injection pain in infants and children. In adults, limited data demonstrate some benefit of topical anesthetics and vapocoolants.

Antibacterial properties of EMLA and lidocaine in wound tissue biopsies for culturing

If a tissue biopsy from a chronic wound is sampled for culture, the antibacterial properties of local anesthetics may pose a problem in producing false-negative results. The purpose of this study was to investigate the effects of EMLA (AstraZeneca) and lidocaine on common wound pathogenic bacteria. An in vitro study of a total of 25 clinical isolates and ATCC reference strains of Staphylococcus aureus (including methicillin-resistant S. aureus), Escherichia coli, Pseudomonas aeruginosa, and Streptococcus pyogenes was conducted. The isolates were exposed to the local anesthetic drugs (and some of their contents separately) at 35 degrees C over a 24-hour period and time-kill curves were recorded. No culture media were used and saline was used for controls. EMLA was found to have a rapid acting and powerful antibacterial effect and should not be used before culturing tissue samples. Lidocaine 1% was found not to inhibit the bacterial strains when exposure time was held below 2 hours. We conclude that culturing tissue from a wound biopsy is safe within 2 hours when a pure, preservative-free lidocaine 1% solution is used.

Anti-inflammatory properties of local anesthetics and their present and potential clinical implications

Development of new local anesthetic agents has been focused on the potency of their nerve-blocking effects, duration of action and safety and has resulted in a substantial number of agents in clinical use. It is well established and well documented that the nerve blocking effects of local anesthetics are secondary to their interaction with the Na+ channels thereby blocking nerve membrane excitability and the generation of action potentials. Accumulating data suggest however that local anesthetics also possess a wide range of anti-inflammatory actions through their effects on cells of the immune system, as well as on other cells, e.g. microorganisms, thrombocytes and erythrocytes. The potent anti-inflammatory properties of local anesthetics, superior in several aspects to traditional anti-inflammatory agents of the NSAID and steroid groups and with fewer side-effects, has prompted clinicians to introduce them in the treatment of various inflammation-related conditions and diseases. They have proved successful in the treatment of burn injuries, interstitial cystitis, ulcerative proctitis, arthritis and herpes simplex infections. The detailed mechanisms of action are not fully understood but seem to involve a reversible interaction with membrane proteins and lipids thus regulating cell metabolic activity, migration, exocytosis and phagocytosis.

Sensitivity of respiratory bacteria to lignocaine

AIM

Lignocaine, a topical anaesthetic agent, is generally used in variable concentrations usually between 2% and 4% on the vocal cords prior to flexible bronchoscopy and bronchoalveolar lavage (BAL) procedures. The aim of this study was to investigate whether 2% or 1% lignocaine significantly inhibits the growth of organisms commonly found in the respiratory tract, in particular Streptococcus pneumoniae.

METHOD

In order to determine the antibiotic effect of lignocaine on lower respiratory tract flora, five different organisms were examined in vitro using well diffusion, disc diffusion and microbroth dilution against 1% and 2% concentrations of lignocaine.

RESULTS

Antimicrobial activity could not be detected using the well diffusion and the disc diffusion methods, as lignocaine failed to diffuse through the media. The microbroth dilution method showed reproducible bactericidal effect of these respiratory isolates against Streptococcus pneumoniae, Moraxella catarrhalis and Haemophilus influenzae at 2% concentration. Lignocaine 2% showed no growth inhibition against Pseudomonas aeruginosa and Candida albicans. Lignocaine 1% also partially inhibited S. pneumoniae.

CONCLUSION

As lignocaine shows significant inhibition of respiratory pathogens such as Streptococcus pneumoniae even at a concentration of 1%, the lowest concentration possible should be used for flexible bronchoscopy and BAL to maximise the chance of recovery of these organisms.

Comparison of topical lidocaine/prilocaine anesthetic cream and local infiltration of 2% lidocaine for episioplasty in mares

Local anesthesia and tissue inflammation associated with lidocaine infiltration and lidocaine/prilocaine topical anesthetic cream for episioplasty in mares were compared. Twenty-two mares were randomly assigned to lidocaine or lidocaine/prilocaine topical anesthetic cream treatment groups. Perineum and vulva were cleaned, 8-12 g (approximately 1 g/cm per side of vulva) of topical anesthetic cream was applied, and the area was covered by plastic wrap 30 min prior to beginning procedure. Alternately, lidocaine was injected (1 mL) every centimeter just prior to the procedure. Episioplasty was conducted using standard methods, but employing simple interrupted sutures. Horses were not sedated and use of a twitch was recorded. Four millimeter punch biopsies were harvested 1, 3, and 10 days following episioplasty and scored for degree of inflammation by a blinded pathologist. Clinical inflammation scores were assigned when biopsies were obtained. Seven of 11 horses receiving lidocaine infiltration required twitching, but none of the horses that received the anesthetic cream required twitching. Six of 11 and seven of 11 of the lidocaine and anesthetic cream groups, respectively, required twitching for episioplasty. Except for the clinical scores on day 3, no statistical differences for clinical and histopathologic scores between samples from the two treatment groups for a given day were identified. Use of lidocaine/prilocaine topical anesthetic cream was as effective as lidocaine infiltration in providing local anesthesia when performing episioplasty in mares. Its use decreased the need for twitching horses as well as the risk of deformation of the labia caused by lidocaine infiltration.

Quantitative tracheal lavage versus bronchoscopic protected specimen brush for the diagnosis of nosocomial pneumonia in mechanically ventilated patients

BACKGROUND

No gold standard method exists for the diagnosis of ventilator-associated pneumonia despite the availability of multiple techniques.

METHODS

A prospective, crossover study was performed on mechanically ventilated patients meeting with suspected pneumonia. Eighteen paired samples were obtained on 15 patients, comparing the results of quantitative tracheal lavage (QTL) to bronchoscopic protected brush specimen (PSB) by quantitative culture and gram stain examination.

RESULTS

The sensitivity, specificity, positive and negative predictive values, and accuracy are affected by the growth density threshold selected, and whether the same organisms are expected by both methods. There is a significant relationship between QTL and PSB (P = 0.0048; R = 0.632), gram stain and PSB (P <0.001; R = 0.791), and gram stain and QTL (P = 0.0125; R = 0.575), by Spearman rank order correlation.

CONCLUSIONS

QTL may have a role for diagnosing and directing treatment of ventilator-associated pneumonia, allowing reservation of bronchoscopic PSB for secondary, high risk and refractory cases.

Sharp wound debridement in local anaesthesia using EMLA cream: 6 years' experience in 1084 patients

Sharp debridement is the most efficient method for clearing the woundbed in the exudation and granulation phase of wound healing. At our clinic the anaesthetic lidocaine-prilocaine cream, EMLA, has been used as an analgesic for sharp debridement since 1994. A review of patients' records was conducted, including ulcer size, dose of cream used, analgesic efficacy and complications. During a 6-year period a total of 1084 patients were treated for leg ulcers, decubitus ulcers, abscess revisions, anal and coccyx fistulae, postoperative wounds, diabetic ulcers and burns. Doses ranging from 3 to 150 g cream were applied for 45-60 min. In all patients except three the analgesia was adequate for debridement. We observed no allergic reactions, no clinical symptoms of local anaesthetic toxicity or methaemoglobinaemia. In 12 patients (1.1%) a burning sensation was reported directly after the application of EMLA cream to the ulcer, which, however, subsided within 15-20 min. In our experience, sharp debridement in percutaneous analgesia with EMLA is efficient, economical, safe, and tolerable for the patient.

Non-preserved 1% lidocaine solution has less antibacterial properties than currently available anaesthetic eye-drops

PURPOSE

Some anaesthetics inhibit bacterial growth, and thus may lead to low rates of positive cultures from bacterial keratitis. Antibacterial properties of lidocaine were compared with those of oxybuprocaine or tetracaine, either in current commercial eye lotions or in extemporaneous solutions.

METHODS

Forty-eight bacterial strains were used to determine the minimum inhibitory and bactericidal concentrations of four commercial eye lotions containing oxybuprocaine or tetracaine, of a non-ophthalmic 1% lidocaine commercial solution and of extemporaneously prepared solutions of oxybuprocaine, tetracaine, lidocaine and benzalkonium.

RESULTS

Most strains had their growth inhibited by 0.2% oxybuprocaine or 0.4% tetracaine, which corresponds to a 1/2 dilution of the commercial eye-drops. Bacterial growth was still observed with a 1% lidocaine solution.

CONCLUSIONS

Currently available anaesthetic eye-drops that are used before corneal specimen collection may lead to false-negative bacterial cultures. Conversely, a non-preserved 1% lidocaine solution might be more appropriate in corneal specimen collection.

Antimicrobial effects of lidocaine in bronchoalveolar lavage fluid

The antimicrobial activity of lidocaine in bronchoalveolar lavage fluid (BAL(f)) was investigated. Clinical respiratory isolates were added to BAL(f) suspensions containing lidocaine and to normal saline. The growth of two of four isolates of Streptococcus pneumoniae was significantly reduced in the presence of lidocaine-BAL(f) compared with controls in saline. Growth of Moraxella catarrhalis isolates was reduced in normal saline when compared with BAL(f) containing lidocaine. There was no effect upon the growth of Haemophilus influenzae, Pseudomonas aeruginosa and Candida albicans isolates. The recovery of isolates of S. pneumoniae may be reduced below the critical threshold of 10(5) cfu/mL during bronchoscopy when using lidocaine as a local anaesthetic.

The effect of lidocaine on bacterial growth in propofol

Extrinsically contaminated propofol has been associated with multiple infectious complications. Injection of propofol is associated with pain that is diminished by the addition of lidocaine. Lidocaine has antibacterial properties at high concentrations, but low concentrations of lidocaine (0.1%) have not been studied. We examined the growth rates of Staphylococcus aureus, Serratia marcescens, Pseudomonas aeruginosa, and Candida albicans in propofol containing disodium edeteate with and without added lidocaine 0.1% 2, 5, and 24 h after inoculation. There was no significant difference in the number of colony-forming units between propofol with and without added lidocaine at any time after inoculation.

IMPLICATIONS

The addition of lidocaine to propofol in concentrations clinically effective in reducing pain on injection had no effect on microbial growth. Adherence to strict aseptic technique is further emphasized.

Evaluation of the invasive techniques for diagnosing bacterial respiratory infections

Bacterial community-acquired respiratory infections are usually sustained by strains highly responsive to antibiotic therapy. Thus, the clinical approach is based on an empirical treatment and does not require the isolation of the causative pathogen and the determination of the bacterial susceptibility to antibiotics. On the other hand, Gram-negative bacteria, most commonly multidrug resistant, frequently affect immunocompromised and nosocomial patients and their identification in cultures is absolutely necessary for proper antibacterial treatment. To this aim, two conventional methods are used, i.e. the blood culture, which is positive only in 20% of pneumonia cases, and the sputum culture, which is not invasive but easily contaminated by oropharyngeal flora. Consequently, invasive techniques for sampling the pathologic specimen, such as the BAL and the PSB, performed with the help of fiberoptic bronchoscope, are needed. The diagnostic power and the limits of both these techniques are analyzed. Moreover, the opportunity to obtain quantitative cultures, which may discriminate between contamination and infection is considered.

Bronchoscopic diagnosis of pneumonia

Lower respiratory tract infections are characterized by significant morbidity and mortality but also by a relative inability to establish a specific etiologic agent on clinical grounds alone. With the recognized shortcomings of expectorated or aspirated secretions toward establishing an etiologic diagnosis, clinicians have increasingly used bronchoscopy to obtain diagnostic samples. A variety of specimen types may be obtained, including bronchial washes or brushes, protected specimen brushings, bronchoalveolar lavage, and transbronchial biopsies. Bronchoscopy has been applied in three primary clinical settings, including the immunocompromised host, especially human immunodeficiency virus-infected and organ transplant patients; ventilator-associated pneumonia; and severe, nonresolving community- or hospital-acquired pneumonia in nonventilated patients. In each clinical setting, and for each specimen type, specific laboratory protocols are required to provide maximal information. These protocols should provide for the use of a variety of rapid microscopic and quantitative culture techniques and the use of a variety of specific stains and selective culture to detect unusual organism groups.

Antibacterial activity of lidocaine in combination with a bicarbonate buffer

BACKGROUND

The antibacterial properties of lidocaine have been previously described. Recent reports indicated that the addition of NaHCO3 to lidocaine reduces the pain associated with the injection. This study was conducted to determine the antibacterial activity of lidocaine buffered with NaHCO3.

METHODS

Rates of killing of six species of bacteria were determined in the presence of buffered and unbuffered lidocaine. When bacteria were incubated with lidocaine buffered with NaHCO3 at either 25, 50, or 100 mEq/L, there was a decrease of > 99% of all bacteria tested over the 6 hours of the assay. This dramatic rate of killing was not observed in the unbuffered control preparations.

RESULTS

The results of this study indicate that NaHCO3 enhances the killing effect that has been described for lidocaine alone. The inability to recover common pathogenic bacteria from biopsy specimens could be the result of exposure to local anesthetic agents such as lidocaine that are buffered with NaHCO3.

The effect of antibiotic therapy on recovery of intracellular bacteria from bronchoalveolar lavage in suspected ventilator-associated nosocomial pneumonia

Intracellular bacteria (ICB) within recovered cells (> 7 percent) obtained via bronchoalveolar lavage (BAL) have been described as predictive of subsequent positive quantitative protected specimen brush (PSB) cultures in patients not receiving antibiotics. To determine the effect of prior or current antibiotic therapy on ICB relative to subsequent PSB culture, we prospectively evaluated 49 consecutive episodes of clinically suspected ventilator-associated pneumonia in 36 patients. Three patient groups were defined based on antibiotic administration: group 1 (current antibiotics), n = 31, samples obtained from patients currently receiving antibiotics; group 2 (recent antibiotics), n = 5, samples obtained from patients who received antibiotics > 48 h but < 72 h prior to sampling; and group 3 (no antibiotics), n = 13, samples from patients receiving no previous antibiotics within 7 days prior to sampling. Overall, PSB cultures (> or = 10(3) cfu/ml) were positive in 14 of 49 (29 percent) samples. In group 1, 2 of 31 (6 percent) samples were positive while 5 of 5 (100 percent) samples in group 2, and 7 of 13 (54 percent) in group 3 were positive. The presence or absence of ICB accurately predicted both positive and negative PSB cultures in 43 of 49 episodes. Of 43 correct predictions, 34 were negative predictions (negative ICB, negative PSB culture). The vast majority of these (29) were obtained from group 1, patients currently receiving antibiotics. In contrast, of nine positive predictions (+ICB, +PSB) virtually all (seven) occurred in group 3, patients receiving no antibiotics. In group 3, 13 of 13 PSB cultures were accurately predicted, either positive or negative, by the presence or absence of ICB. Of seven positive PSB cultures in groups 1 and 2, only 2 (28 percent) were accurately predicted by ICB. From both samples, the cultured organism was resistant to all administered antibiotics. These data suggest both prior and current antibiotic therapy reduces recovery of ICB from BAL and reduces predictive accuracy of ICB for subsequent positive PSB cultures. However, negative prediction by ICB for subsequent negative PSB cultures was good. In contrast, ICB obtained from patients not receiving antibiotics are highly predictive of subsequent PSB culture results, both positive and negative. We do not recommend BAL for evaluation of ICB in patients currently receiving antibiotics or with a recent history of antibiotic use.

Damage to tissue defenses by EMLA cream

EMLA is a new topical agent that safely anesthetizes intact skin. The purpose of this study was to determine if this cream could be safely used for anesthetizing wounds. This investigation evaluated the potential toxicity of EMLA cream in wounds by measuring its effect on host defenses and on the biology of wound repair. In contaminated wounds, EMLA cream elicited an exaggerated inflammatory response that damaged host defenses, inviting the development of infection. As a result of these investigations, we do not recommend the use of EMLA cream in wounds.

Cocaine hydrochloride and benzoylecgonine have no in vitro inhibitory effect against Neisseria gonorrhoeae

We evaluated 72 clinical Neisseria gonorrhoeae isolates for in vitro susceptibility to cocaine hydrochloride and its metabolite benzoylecgonine and to penicillin, tetracycline, erythromycin, ceftriaxone, and ofloxacin. Although there was a wide range of susceptibilities to the antimicrobial agents, cocaine and its major metabolite, benzoylecgonine, had no demonstrable antigonococcal activity. Cocaine use is frequently associated with outbreaks of sexually transmitted disease. We hypothesized that the dramatically decreasing incidence of gonorrhea over the past 15 years may be in part due to pharmacological effects of cocaine. However, since cocaine and its metabolite have no in vitro antigonococcal activity, this hypothesis is unlikely.

Utility of bronchoscopic sampling techniques for cryptococcal disease in AIDS

Although cryptococcal pneumonia is a well recognized complication of the acquired immunodeficiency syndrome, optimal diagnostic approaches remain to be defined. During a 32-month period (October 1984 to June 1987), 11 patients were diagnosed with CP at our institution. The diagnosis was established in all 11 patients from specimens obtained via fiberoptic bronchoscopy (ten) and/or double-lumen catheter lavage (one). Direct stains of sedimented bronchoalveolar lavage were positive for organisms characteristic of Cryptococcus neoformans in nine of 11 patients. Transbronchial biopsies were positive (special histologic stains) in six of eight patients; bronchial washings were positive (direct smear) in seven of ten patients, the bronchial brushings were positive on stain in six of nine patients, and in one patient, a Wang transbronchial needle aspirate was positive on stain. Fungal cultures were positive on the BAL in seven of 11 patients, and on the bronchial washings in four of ten patients; the TBBx culture samples were all negative (zero of three). The serum cryptococcal antigen titer was elevated (median = 1:1024) in all eight patients in which it was assayed. Our data suggest that BAL and bronchial washings have a combined sensitivity on smear equal to that of TBBx and superior to that of TBBx fungal culture. The TBBx does not appear to be necessary in this setting. In addition, an elevated serum cryptococcal antigen titer appears to be an important adjunct in the evaluation of pulmonary infiltrates in AIDS.

Diagnostic fiberoptic bronchoscopy and protected brush culture in patients with community-acquired pneumonia

A model for performing fiberoptic bronchoscopy as a supplement to noninvasive diagnostic methods, in patients with community-acquired pneumonia, was prospectively studied. Twenty-four patients underwent bronchoscopy, seven pilot patients and 17 of 277 (6 percent) consecutive patients with CAP. Indications for FOB were early therapy failure (less than or equal to 72h)(n = 7), late therapy failure (greater than 72h)(n = 11), or before start of antibiotic therapy in severely ill or immunocompromised patients (n = 6). Samples were obtained by aspiration of bronchial secretion and with a protected brush catheter from which quantitative cultures with a detection level of 10(4) colony forming units per ml were performed. Results concluded that FOB, with the use of quantitative PB-cultures, offered a safe and specific diagnostic tool, which on special indications, can be of great value in the management of patients with CAP.

Bacterial arthritis: are fever, rigors, leucocytosis and blood cultures of diagnostic value?

Clinical suspicion, positive gram stains and cultures of the synovial fluid are the fundamental criteria for the diagnosis of bacterial arthritis. Bacterial arthritis may, however, show an oligosymptomatic clinical course and thus lead to a delay in diagnosis. The case records of 43 patients with bacterial arthritis were reviewed retrospectively. Rigors (20.9%), fever (40.5%), blood leucocytosis (41.8%) and a shift to the left of blood leucocytes (35%) were found in less than half of all examined patients. Positive cultures of the synovial fluid (71.4%) were far more frequent than positive blood cultures (23.5%). We conclude, that the absence of fever, rigors, blood leucocytosis and positive blood cultures does not rule out the possibility of bacterial arthritis.

Safety and efficacy of using high-dose topical and nebulized anesthesia to obtain endobronchial cultures

We evaluated the safety and efficacy of high-dose topical and nebulized airway anesthesia in normal volunteers and in patients undergoing diagnostic fiberoptic bronchoscopy. Lidocaine solution (4 percent) was used for gargling, for spraying the palate and oropharynx with an atomizer, and for nebulization with an air-powered nebulizer (mean total dose, 1,682 mg) and 2 percent lidocaine (Xylocaine) jelly for anesthetizing nasal passages. In six normal subjects and in eight patients, lidocaine blood levels were measured at baseline, after gargling, after spraying, after nebulization, and then at 5, 10, 15, 30, and 60 min; 19 normal subjects and ten patients underwent the same anesthesia protocol but had no blood drawn. Fiberoptic bronchoscopy was performed in 21 normal volunteers and in 18 patients and cultures obtained using the protected specimen brush. Additional endobronchial lidocaine (mean 256 mg) was given to the 18 patients after collecting the microbiology specimens. Peak lidocaine blood levels remained below 6 micrograms/ml in all cases. Cough and discomfort during bronchoscopic examination was absent or minimal in 17 of 21 normal subjects (80 percent) and in 14 of 18 patients (77 percent) and was severe in only one instance (5 percent). There were no related complications. Using only topical and nebulized anesthesia is safe and effective for performing fiberoptic bronchoscopy, especially when bacterial cultures are to be obtained and endobronchial instillation of lidocaine must be avoided.

The use of fibreoptic bronchoscopy with sterile catheter in the diagnosis of pneumonia

The use of fibreoptic bronchoscopy with sterile catheter sampling of pulmonary secretions was evaluated in 70 patients with a provisional diagnosis of pneumonia. In 37 patients quantitative analysis of the sterile catheter isolates was performed (colony forming units (CFU) per ml). Potential bacterial pathogens were isolated in 37 patients and in the quantitative analysis, 14 of 22 isolates were grown in counts greater than or equal to 10(3) CFU/ml. Sterile catheter increased the bacterial isolation rate as in only 19 patients blood (2) or sputum (18) cultures yielded the same organisms. Sputum cultures showed a 25% false-positive rate in patients with no growth from sterile catheter. Quantitative analysis did not yield any further information in patients receiving antibiotics. Atypical or fungal pneumonia was diagnosed in 22 patients, while ten patients had other pathology simulating pneumonia. Sterile catheter sampling of pulmonary secretions at fibreoptic bronchoscopy proved to be a valuable tool in the diagnosis of bacterial pneumonia.

Use of a bronchoscopic protected catheter technique in the clinical evaluation of a new antibiotic

We prospectively compared the usefulness of a bronchoscopic protected catheter technique with the results from sputum cultures in the evaluation of moxalactam, a new beta-lactam antibiotic. The significance of a given isolate on protected catheter culture was determined by quantitative bacteriology. 32 patients with community-acquired pneumonia were enrolled in the study and 31 grew common lower respiratory tract pathogens from their protected catheter specimen. The most common single pathogens recovered were Streptococcus pneumoniae (11 patients) and Haemophilus influenzae (2). Mixed flora, predominantly anaerobes, were isolated from 15 patients, and 3 patients had mixed aerobic infections. All seven bacteremic cases had the identical organism isolated from the protected catheter specimen, confirming the accuracy of the technique. Comparisons with sputum cultures showed that the predominant organism on sputum culture was the same as that obtained from the protected catheter culture in only 13% of the cases. Sputum cultures revealed either no pathogen or a different pathogen in 23 cases, and no sputum could be obtained in 4. Compared to cultures of expectorated sputum, we found the protected catheter bronchoscopic culture technique to have the following advantages in the bacteriologic evaluation of moxalactam: 1) greater accuracy and sensitivity in bacteremic patients; 2) accurate delineation of the bacteriology of infections; and 3) a higher percentage of patients with evaluable bacteriology leading to greater efficiency during the investigation.