Wide Spectrum Antimicrobial Agent Research Articles

The antimicrobial effect of Limosilactobacillus reuteri as probiotic on oral bacteria: A scoping review

The antimicrobial effect of Limosilactobacillus reuteri as probiotic on oral bacteria: A scoping review

The antimicrobial effect of Limosilactobacillus reuterias probiotic on oral bacteria: A scoping review.

Dysbiosis among oral microbial community in the oral cavity can lead to several oral diseases. Probiotic therapy is known to correct these imbalances. Limosilactobacillus reuteri is one of the most studied strains of probiotics and can control oral microbiota through reuterin, a wide-spectrum antimicrobial agent. The objective of this review was to evaluate the effect of the antimicrobial activity of Limosilactobacillus reuteri on the oral bacteria of humans. This review used PubMed, Scopus, EMBASE, ScienceDirect, and Google Scholar databases as bibliographic resources. Studies with matching keywords were analyzed and screened with PRISMA-ScR recommendations. Sixteen articles were selected for this review, which included a total of 832 patients. Based on this review, Limosilactobacillus reuteri has a strong antibacterial effect against Streptococcus mutans in healthy individuals but is not effective against Lactobacillus. Additionally, it has a significant antibacterial effect against Porphiromonas gingivalis in patients with periodontitis, although its effectiveness is not stable in patients with peri-implant infections. Furthermore, Limosilactobacillus reuterihas varying results against other bacteria, indicating the need for further extensive research to ensure its efficacy.

THE EMPIRIC ANTIMICROBIAL THERAPY: THE COMPARISON OF INITIAL CHOICE WITH THE RESULTS OF MICROBIOLOGICAL INVESTIGATIONS. AN OBSERVATIONAL STUDY

Introduction: Hospital infections are serious medical problem, causing deterioration in patients’ outcome, prolonged hospital stay and increase costs of hospitalization. Rapid administration of wide spectrum antimicrobial agents is a well known way to increase patient survival rate. Aim: To analyze the efficacy of initial empiric antimicrobial treatment in a large academic hospital. Methods: In this retrospective cohort study, the initial choice of empiric therapy was compared with the results of the microbiological investigation and the susceptibility/resistance of isolated pathogens. Results: Between February 1, 2018 and February 1, 2020, a total number of 267 samples were analyzed. Amongst all 267 samples 163 (61%) were positive and 104 (39%) were negative. In those 163 samples 247 pathogens were isolated. In empirical therapy the most frequently administered antibiotic was meropenem (55/267, 20.6%), vancomycin (16/267, 6%), meropenem with vancomycin (14/267, 5.2%), ceftazidime (11/267, 4.1%), and imipenem/cilastatin (5/267, 1.9%). The total number of samples where the empiric therapy corresponded with the results of microbiological tests was 166. There were forty-seven (28.3%) Gram positive bacteria, including 11 MRSA and 1 VRE, and 119 (71.7%) Gram negative pathogens, including 35 K. pneumoniae ESBL+, 12 A. baumannii, and 2 E. coli ESBL+. In 81 cases, the isolated pathogens were resistant to empirically administered drugs. The empiric antimicrobial therapy complied with the results of microbiological analyses in 67.2% (166/247) of cases. Conclusion: In our center, meropenem and vancomycin seem to be a good choice in empiric therapy.

Solubility Enhancement of Rifabutin by Co-solvency Approach

Rifabutin is wide spectrum antimicrobial agent, effective in the treatment of infection caused by M. tuberculosis, M. avium and M. Leprae and also used in the treatment of multidrug resistant TB. Rifabutin is very poorly water soluble drug (0.19mg/ml) with high permeability. For enhancement of solubility of a hydrophobic drug has a significant role in the development of a liquid dosages form. The main purpose of this study was to improve the solubility of Rifabutin by co solvency method. Different blends were prepared by usinf different solvents and surfactants in different proportions have been used to enhance the solubility of Rifabutin like water, phosphate buffer, ethanol, propylene glycol and PEG 400, Tween 80 and Brij 35. In thisit was found that the blend 90% PEG and 10% co solvents (ethanol and propylene glycol) give highest solubility and among the surfactant systems, Tween 80 had shown enhanced solubility of Rifabutin. Solubility of rifabutin was determined by preparing saturated solutions of rifabutin in pure solvents and in mixture of co solvents with or without surfactants. It observed that the blend of 90% PEG and 10% ethanol and propylene glycol had shown the better improvement of solubility when compared with the other solvents and co solvents as it caused a noteworthy enhancement in solubility of Rifabutin that was 1.6803 mg/ml.The above observations lead to propose that the addition of small amount of polar solvent enhances the solubility of drug.Thus, the study generated an important array of data to compare the effect of these cosolvents on the aqueous solubility of rifabutin.

AgO Nanowires: Synthesis, Characterization and Bioactivity

This study is focused on Nanostructured AgO due to its novel properties. Here AgO-NWs manufactured bylow-cost, fast green synthesis using curcumin extract. AgO-NWs structures were characterized by FESEMfield emission electron microscope scanning. Uniform distribution can be seen for the AgO -NWs. TheAgO -NWs thin film exhibits a promising giant third-order nonlinearity and ultrafast character. It behavesas a tunable refraction and absorption character the exciting energy is varied in the range of 80–120 mJ.Silver is a wide-spectrum natural antimicrobial agent that applies to patented wound dressings with broadapplications. Today, AgO -NWs have attracted attention in Biophotonic Sensor. Here, AgO-NWs used to asantimicrobial agent against common infecting pathogenic microbes E-coli. The results demonstrated that theAgO-NWs against pathogenic bacterial organisms, they have possible antimicrobial activity and could beregarded as an alternative antibacterial agent.

Development of Silver Nanoparticles/Gelatin Thermoresponsive Nanocomposites: Characterization and Antimicrobial Activity.

Skin and soft tissue infections involve microbial invasion of the skin and underlying soft tissues. To overcome this problem, nanocomposites were obtained using gelatin as a biopolymer scaffold and silver nanoparticles as a wide spectrum antimicrobial agent. Water and glycerol have been used as solvents for the gelatin hydrogel synthesis. This mixture led to a stable and homogeneous biomaterial with improved mechanical properties. Silver nanoparticles were characterized using SEM, EDS and TEM. Moreover, the AgNp/gelatin nanocomposite obtained using these nanoparticles was characterized using SEM and FTIR. Moreover, mechanical and swelling properties were studied. The storage modulus was 3000 Pa for gelatin hydrogels and reached 5800 Pa for AgNp/gelatin nanocomposite. Silver nanoparticles have been studied as an alternative to antibiotics. Importantly, the rate of silver release was modulated as a function of the temperature of the nanocomposite. Thus, the silver release from the nanocomposites at 24 °C and 38 °C was analyzed by atomic absorption spectroscopy. The silver release reached 25% after 24 h at 24 °C, while a 75% release was achieved at 38°C in the same period, showing the material thermoresponsive behavior. AgNp/gelatin nanocomposite showed a deleterious effect over 99.99% of Pseudomonas aeruginosa and Staphylococcus aureus, leading to a material with antimicrobial properties. AgNp/gelatin nanocomposite with improved mechanical properties and silver nanoparticles as a source of silver ions has been synthesized. The properties of the nanocomposite with controlled silver delivery result in a more efficient topical pharmaceutical form for wound healing applications.

A review on efficacy and tolerability of tea tree oil for acne

Acne is common problem acquired generally after puberty. It ranges from mild to moderate: papules, pustules, nodules to severe cyst. Various natural therapy can be employed for treatment of acne including Tea tree oil (TTO). Tea tree oil has wide spectrum anti-microbial agent showing in treatment of acne. Usually it is utilized in various topical preparations. It contains more than 80-90% monoterpenes namely terpinen-4-ol, -cymene, α-terpinene, limonene 1,8-cineol, α-terpineol, terpinolene,  1,8-cineol, sabinene and  α-pinene,  The European cosmetic Association recommended not more than 1% use of tea tree oil in cosmetic preparations. In this review, we listed various efficacy and tolerability studies along with challenges in application of tea tree oil in cosmetics and dermatological preparations. TTO is a moderate sensitizer and upon oxidation it increases in its allergenic potency. This is a comprehensive review of using Tea tree oil against various microbial species. Various studies revealed the use of TTO as anti-bacterial, anti-fungal, anti- oxidant agent. TTO is effective treatment option that can further be utilized in preparation of novel formulations like liposomes, ethosomes along with combination with other anti-microbial and anti-oxidant agents. Keywords: Acne, Tea-tree oil, Application, Antioxidant, Nano particles.

Identification of Novel Cryptic Multifunctional Antimicrobial Peptides from the Human Stomach Enabled by a Computational–Experimental Platform

Novel approaches are needed to combat antibiotic resistance. Here, we describe a computational-experimental framework for the discovery of novel cryptic antimicrobial peptides (AMPs). The computational platform, based on previously validated antimicrobial scoring functions, indicated the activation peptide of pepsin A, the main human stomach protease, and its N- and C-terminal halves as antimicrobial peptides. The three peptides from pepsinogen A3 isoform were prepared in a recombinant form using a fusion carrier specifically developed to express toxic peptides in Escherichia coli. Recombinant pepsinogen A3-derived peptides proved to be wide-spectrum antimicrobial agents with MIC values in the range 1.56-50 μM (1.56-12.5 μM for the whole activation peptide). Moreover, the activation peptide was bactericidal at pH 3.5 for relevant foodborne pathogens, suggesting that this new class of previously unexplored AMPs may contribute to microbial surveillance within the human stomach. The peptides showed no toxicity toward human cells and exhibited anti-infective activity in vivo, reducing by up to 4 orders of magnitude the bacterial load in a mouse skin infection model. These peptides thus represent a promising new class of antibiotics. We envision that computationally guided data mining approaches such as the one described here will lead to the discovery of antibiotics from previously unexplored sources.

Fermentation, Extraction and Characterization of Antimicrobial Agent from Marine Saccharomonospora viridis AHK 190

S TUDY is aimed to ferment, isolate and characterize a significant antimicrobial metabolite from the marine thermophilic, Saccharomonospora viridis AHK 190. Maximum yield of a wide spectrum antimicrobial agent was optimized and fermented by Saccharomonospora viridis AHK 190. Extraction, purification and molecular formula elucidation of the fermented agent were also assayed. A diversity of human microbial pathogens was applied as indicators in the antibiosis assay. Thin layer chromatography technique was employed for partial purification of the antimicrobial agent. Spectral and elemental analysis studies were as well screened for molecular formula elucidation of the purified compound. Actinomycete optimum growth and maximum antibiotic fermentation were confirmed after 3 days of incubation at 55oC under the effect of pH at 8.0 and shaking at 180 rpm. In addition, maximum antibiotic production was achieved with galactose, aspartic acid, 3.0% NaCl and 0.11% K2HPO4; while pyridoxine, starch, 5.0% NaCl and 0.11% K2HPO4 encouraged the actinomycete optimum growth. Elucidated molecular formula of the under-test antimicrobial compound was found as C31H34O4S3 of molecular weight = 567. It is of a new chemical formula different from other current main classes of antibiotics.

Novel Series of Quaternary Ammonium Surfactants Based on 2,3-Dihydro- [1,4]dioxino[2,3-b]pyridin-7-ol Ring: Synthesis, Analysis and Antimicrobial Evaluation

Background: The quaternary ammonium compounds (QAC) are the important group of chemical individuals with widespread usage in many fields of industry or science. The surface-active cationic surfactants are well known disinfection agents. Its effectivity against gram-positive, gramnegative bacteria, yeasts and some viruses is already used in many preparations. On the other hand, the emergence of resistance is the cause of an increasing necessity of new substances. Methods: The series of 5-alkyl-7-hydroxy-2,3-dihydro-[1,4]dioxino[2,3-b]pyridin-5-ium bromides has been synthesized as a novel potential antimicrobial agent. Reaction of the nucleophilic substitution type has been used. The novel compounds have been tested as disinfection agents against bacteria and fungi. The microdilution broth method was utilized for antimicrobial evaluation. Standard MTT test was used for cytotoxic evaluation. Results: We have prepared 5 new compounds based on 2,3-dihydro-[1,4]dioxino[2,3-b]pyridin-7-ol with different length of lipophilic alkyl chain on the quaternary nitrogen (C10-18). The compounds were characterized with analytical data (NMR, HRMS) and evaluated as wide spectrum antimicrobial agents against pathogenic fungal and bacterial strains. We have observed the efficacy towards microbial cells of C12 and C14 compounds for only several antimicrobial strains (Staphylococcus aureus, Candida krusei, Candida glabrata, Trichophyton mentagrophytes). Conclusion: We report on the preparation and characterization of a set of novel cationic surfactant-like compounds based on 2,3-dihydro-[1,4]dioxino[2,3-b]pyridin-7-ol. The novel compounds have been evaluated as wide spectrum antimicrobial agents against pathogenic fungal and bacterial strains. Only two compounds with alkyl chain C12 and C14 showed significant activity against microbes. So, these two compounds should be considered as the potential disinfectants with the selective effect against certain bacterial and fungal strains, not as wide spectra antimicrobial agents. Keywords: Cationic surfactants, quaternary ammonium compounds, synthesis, antimicrobial activity, disinfectants, fungal strain.

Antimicrobial Activities and In silico Analysis of Methoxy Amino Chalcone Derivatives

A series of methoxy-4’-amino chalcone derivatives were tested for their antimicrobial activities against Escherichia coli ATCC 25923, Staphylococcus aureus ATCC 25922 and Candida albicans ATCC 10231. Furthermore, their molecular interactions with dihydropteroate synthase (DHPS) of E. coli and S. aureus were studied with a docking experiment. Compound 4 ((E)-1-(4-aminophenyl)-3-(2,3-dimethoxyphenyl)prop-2-en-1-one) exhibited the strongest activity, in which its activity was equal to sulfamerazine and sulfadiazine used as positive controls. In addition, it showed a good potential to be used as a wide spectrum antimicrobial agent. The in silico experiment showed that the prepared compounds had higher affinity to DHPS of S. aureus than to DHPS of E. coli. The tested compounds showed high similarity interaction with hydroxymethylpterin pyrophosphate (natural substrate of DHPS) in building intermolecular interactions.

Impact of Penicillin Nonsusceptibility on Clinical Outcomes of Patients with Nonmeningeal Streptococcus pneumoniae Bacteremia in the Era of the 2008 Clinical and Laboratory Standards Institute Penicillin Breakpoints

To investigate the impact of penicillin nonsusceptibility on clinical outcomes of patients with nonmeningeal Streptococcus pneumoniae bacteremia (SPB), a retrospective cohort study was performed. The characteristics of 39 patients with penicillin-nonsusceptible SPB (PNSPB) were compared to those of a group of age- and sex-matched patients (n = 78) with penicillin-susceptible SPB (PSSPB). Susceptibility to penicillin was redetermined by using the revised Clinical and Laboratory Standards Institute (CLSI) penicillin breakpoints in CLSI document M100-S18. Although the PNSPB group tended to have more serious initial manifestations than the PSSPB group, the two groups did not differ significantly in terms of their 30-day mortality rates (30.8% versus 23.1%; P = 0.37) or the duration of hospital stay (median number of days, 14 versus 12; P = 0.89). Broad-spectrum antimicrobial agents, such as extended-spectrum cephalosporins, vancomycin, and carbapenem, were frequently used in both the PNSPB and PSSPB groups. Multivariate analysis revealed that ceftriaxone nonsusceptibility (adjusted odds ratio [aOR] = 4.88; 95% confidence interval [CI] = 1.07 to 22.27; P = 0.041) was one of the independent risk factors for 30-day mortality. Thus, when the 2008 CLSI penicillin breakpoints are applied and the current clinical practice of using wide-spectrum empirical antimicrobial agents is pursued, fatal outcomes in patients with nonmeningeal SPB that can be attributed to penicillin nonsusceptibility are likely to be rare. Further studies that examine the clinical impact of ceftriaxone nonsusceptibility in nonmningeal SPB may be warranted.

Biochemical studies on the production of Sparsomycin antibiotic by Pseudomonas aeurginosa, AZ-SH-B8 using plastic wastes as fermented substrate

Hundred and twenty microbial isolates could be isolated from different soil samples collected from different localities in Egypt. One of the bacterial cultures AZ-SH-B8 was found to produce a wide spectrum antimicrobial agent when cultivated on plastic wastes. The bacterial culture AZ-SH-B8 could be isolated from a soil sample collected from Sharkia governorate, Egypt. From the taxonomic features, the bacterial isolate AZ-SH-B8 matches with Pseudomonas aeurginosa in the morphological, physiological and biochemical characters and confirmation by using API20E system. Thus, it was given the suggested name P. aeurginosa, AZ-SH-B8. The parameters controlling the biosynthetic process of antimicrobial agent formation includes: innoculum size, different pH values, different temperatures, different incubation period, different carbon and nitrogen sources and different mineral salts concentrations (KNO3, K2HPO4, MgSO4·7H2O and KCl) were fully investigated. The active metabolite was extracted using n-butanol (1:1, v/v) at pH 7.0. The separation of the active ingredient and its purification was performed using both thin layer chromatography (TLC) and column chromatography (CC) techniques. The physico-chemical characteristics of the purified antibiotic viz. color, melting point, solubility, elemental analysis, spectroscopic characteristics and chemical reactions have been investigated. This analysis indicates a suggested empirical formula of C13H21N3O6S2. The minimum inhibition concentrations “MICs” of the purified antimicrobial agent were also determined. The purified antimicrobial agent was suggestive of belonging to Sparsomycin antibiotic produced by P. aeurginosa, AZ-SH-B8.

Physico-chemical characteristics of vernamycin-A antibiotic biosynthesis by streptomyces SP-AZ-SH-29

Seventy-five actinomycete isolates were isolated from different soil samples collected from different localities in Egypt. One of the actinomycete culture AZ-SH-29 from three cultures was found to produce a wide spectrum antimicrobial agent. The actinomycete isolate AZ-SH-29 matches with Streptomyces ramulosus in the morphological, physiological, and biochemical characters. Thus, it was given the suggested name Streptomyces ramulosus-AZ-SH-29. The parameters controlling the biosynthetic process of the antimicrobial agent formation including; different pH values, different temperatures, different incubation period, and different carbon and nitrogen sources, were fully investigated. The active metabolite was extracted using ethyl acetate (1:1, v/v) at pH 7.0. The separation of the active ingredient and its purification were performed using column chromatography (CC) technique. The physico-chemical characteristics of the purified antimicrobial agent have been investigated. This analysis indicates a suggested imperical formula of C20H25N2O5. The minimum inhibition concentrations “MICs” of the purified antibiotic and antiviral test were also determined. The purified antimicrobial agent was suggestive of being belonging to Depsipeptide (Mikamycin) group (Vernamycin-A antibiotic) produced by Streptomyces ramulosus, AZ-SH-29.

Controlled Release of Farmazin from Thermosensitive Gels Based on Poly(N-vinylcaprolactam)

With the aim to prolong the effect of a wide-spectrum antimicrobial agent, Farmazin (tylosine tartrate), this drug was immobilized on a gel of N-vinylcaprolactam-sodium itaconate copolymer, which undergoes a phase transition on heating. The phase transition, accompanied by a change in volume, in aqueous solutions of the pure copolymer gel and that with the immobilized drug was studied.

Alteration of Escherichia coli Topoisomerase IV to Novobiocin Resistance

DNA gyrase and topoisomerase IV (topo IV) are the two essential type II topoisomerases of Escherichia coli. Gyrase is responsible for maintaining negative supercoiling of the bacterial chromosome, whereas topo IV's primary role is in disentangling daughter chromosomes following DNA replication. Coumarins, such as novobiocin, are wide-spectrum antimicrobial agents that primarily interfere with DNA gyrase. In this work we designed an alteration in the ParE subunit of topo IV at a site homologous to that which confers coumarin resistance in gyrase. This parE mutation renders the encoded topo IV approximately 40-fold resistant to inhibition by novobiocin in vitro and imparts a similar resistance to inhibition of topo IV-mediated relaxation of supercoiled DNA in vivo. We conclude that topo IV is a secondary target of novobiocin and that it is very likely to be inhibited by the same mechanism as DNA gyrase.

Effects of topical chlorhexidine applied to the rabbit nasal mucosa

Objective: To search the effects of administration of various concentrations of a wide-spectrum antimicrobial agent, chlorhexidine, to the nasal mucosa. Material and methods: About 0.20, 0.12, 0.06 and 0.03% concentrations of chlorhexidine gluconate were applied to the rabbit nasal mucosa as one puff twice a day throughout 5 days. Another group, treated with serum saline to the nose, behaved as the control group. On the fifth day following drug administration, specimens were taken from nasal mucosa of the rabbits and examined under light microscope. Results: As a result of comparison between drug treated group and control group, with increasing drug concentrations progressively increased neutrophil infiltration in mucosa, ciliary loss in cells, and occasional metaplasia were observed. Conclusion: There is a linear, positive and strong association between concentrations of chlorhexidine and its irritative effects on rabbit nasal mucosa. While 0.20 and 0.12% concentrations of chlorhexidine cause excess irritation on the nasal cavity, 0.06 and 0.03% concentrations of chlorhexidine gluconate causes lower irritation and effects on the animals which have experimentally induced rhinosinusitis must be evaluated.

Liver transplantation in patients with Caroli's disease and recurrent cholangitis

Abstract. Caroli's disease is an uncommon congenital disorder of the intrahepatic biliary tree. It is characterized by multiple and segmental dilatations of the bile ducts. The clinical course of Caroli's disease is often complicated by recurrent episodes of bacterial cholangitis that seriously impair the patient's quality of life. Despite wide spectrum antimicrobial agents, medical treatment of cholangitis is frequently unsuccessful in patients with Caroli's disease due to the persistence of bacteria in dilatated bile ducts. Other therapies, including internal or external biliary drainages and various surgical or endoscopic procedures, have been used in the treatment of Caroli's disease, with poor results. There are no previous reports in the literature of liver transplantation for recurrent cholangitis in patients with Caroli's disease. We present two such cases, in which cholangitis is resolved.

An Unusual Combination of Peptides from the Skin Glands of Ewing's Tree Frog, Litoria ewingi. Sequence Determination and Antimicrobial Activity

The dorsal glandular skin extract of the brown tree frog Litoria ewingi contains six major peptides. The amino acid sequences of the peptides were determined by using a combination of mass spectrometry and automated Edman sequencing. One of the peptides, caerin 1.1 [Gly Leu Leu Ser Val Leu Gly Ser Val Ala Lys His Val Leu Pro His Val Val Pro Val Ile Ala Glu His Leu (NH2)], has been isolated previously from Australian tree frogs of the genus Litoria, and is a wide-spectrum antimicrobial agent. The roles of the other five peptides in the amphibian skin have not, as yet, been determined. The most abundant peptide, uperin 7.1 [Gly Trp Phe Asp Val Val Lys His Ile Ala Ser Ala Val (NH2)], shows structural similarity to the uperin group of antimicrobial peptides isolated from toadlets of the genus Uperoleia (except that uperin 7.1 lacks the final four amino acid residues of uperins from the genus Uperoleia). The significance of this finding hinges upon the distant evolutionary relationship of Litoria and Uperoleia. If the structural similarity implies a single evolutionary origin, it also implies a conservation of structural origin for at least 100 million years. Evolutionary convergence is a more likely explanation for the structural similarity of the peptides from the two genera. A related peptide, uperin 7.1.1, lacks the first two amino acid residues from the N-terminal end of uperin 7.1. Uperin 7.1 exhibits minor antimicrobial activity while uperin 7.1.1. is inactive. The three other peptides are caeridin 7.1 [Gly Leu Leu Asp Met Val Thr Gly Leu Leu Gly Asn Leu (NH2)] and two modified peptides of the tryptophyllin group which we have named tryptophyllin 6.1 [Leu Phe Phe Trp Gly (NH2)] and 7.1 [Ile Phe Phe Phe Pro (NH2)]. Tryptophyllins 6.1 and 7.1 are related to similar peptides isolated from the Australian red tree frog Litoria rubella: such peptides may be neurotransmitters or neuromodulators.

Spontaneous bacterial peritonitis in cystic fibrosis.

Bacterial peritonitis presents with classic symptoms of fever and abdominal pain. Some patients, however, are completely asymptomatic. Death in the short term is considerable, especially in patients with alcoholic cirrhosis. Cystic fibrosis patients occasionally develop biliary cirrhosis and may have secondary hypersplenism, varices, and ascites. These patients should be at risk for spontaneous bacterial peritonitis. Spontaneous bacterial peritonitis is described in two patients with longstanding hepatic cirrhosis secondary to cystic fibrosis. Both had required splenectomy for complications of portal hypertension. This is a previously unreported, but potentially fatal, complication of cystic fibrosis liver disease. Early diagnostic paracentesis is essential so that appropriate acute management, including antimicrobial treatment can be started. In the long term, these patients deserve immediate paracentesis for any evidence of recurrence. Whether the patient is treated with chronic (continuous) antimicrobial prophylaxis or only receives antimicrobial treatment during periods when bacteraemia is possible (for example, dental work, bronchoscopy), it would seem reasonable in patients with cystic fibrosis to use a wide spectrum antimicrobial agent with activity against Pseudomonas aeruginosa, other common Gram negative organisms, and Staphylococcus aureus.