In vitro activity of telithromycin (HMR3647), a new ketolide, against clinical isolates of Mycoplasma pneumoniae in Japan

In Vitro Activities and Spectrum of the Novel Fluoroquinolone Lascufloxacin (KRP-AM1977)

Lascufloxacin exhibited a broad spectrum of activity against various clinical isolates. Furthermore, lascufloxacin showed the most potent activity against Gram-positive bacteria among the quinolones tested and incomplete cross-resistance against existing quinolone-resistant strains. Enzymatic analysis indicated that lascufloxacin had potent inhibitory activity against both wild-type and mutated target enzymes. These results suggest that lascufloxacin may be useful in treating infections caused by various pathogens, including quinolone-resistant strains.

Transport of Azithromycin into Extravascular Space in Rats

Recent clinical trials showed a prolonged retention of subinhibitory concentrations of unbound azithromycin in the interstitial fluid of soft tissues despite the fact that azithromycin is extensively distributed in tissues. In these clinical trials, interstitial fluid samples were obtained by using the microdialysis method, and it was established that drug concentrations represent protein-unbound drug concentrations. The present study was designed to measure total azithromycin concentrations in the interstitial fluid of the skin of rats by directly collecting interstitial fluid samples from a pore formed on the skin by a dissolving microneedle array. The total azithromycin concentrations in interstitial fluid of the skin were about 4 to 5 times higher than those in plasma throughout the experimental period, and stasis of the azithromycin concentration in interstitial fluid was observed when the concentration of azithromycin in plasma was at the lower limit of quantification. In addition, the skin/plasma concentration ratio transiently increased after dosing (from 4.3 to 83.1). Our results suggest that azithromycin was trapped inside white blood cells and/or phagocytic cells in not only blood but also interstitial fluid, resulting in a high total azithromycin concentration and the retention of its antimicrobial activity at the primary infection site. The stasis of azithromycin in interstitial fluid and skin would lead to long-lasting pharmacological effects (including those against skin infection) at concentrations exceeding the MIC.

Mycoplasma pneumonia: Clinical features and management

Mycoplasma pneumonia is a common respiratory pathogen that produces diseases of varied severity ranging from mild upper respiratory tract infection to severe atypical pneumonia. Apart from respiratory tract infections, this organism is also responsible for producing a wide spectrum of non-pulmonary manifestations including neurological, hepatic, cardiac diseases, hemolytic anemia, polyarthritis and erythema multiforme. This review focuses on molecular taxonomy, biological characteristics, epidemiology, clinical presentation, radiology and various laboratory tools in diagnosis, differential diagnosis, treatment and prevention of mycoplasma pneumonia.

Intracellular pharmacokinetics of telithromycin, a ketolide antibiotic, in alveolar macrophages

OBJECTIVES

Telithromycin, a ketolide antibiotic, has an antibacterial range that covers intracellular parasitic pathogens that survive or multiply intracellularly in alveolar macrophages. The intracellular pharmacokinetics of TEL in alveolar macrophages was evaluated in vitro.

METHODS

Telithromycin (50 microm) was applied to NR8383 as cultured alveolar macrophages, followed by incubation at 37 degrees C or 4 degrees C. After incubation, the amount of telithromycin in cells was determined.

KEY FINDINGS

Telithromycin exhibited high accumulation in NR8383 and its intracellular accumulation was temperature dependent. Also, telithromycin distributed to the organelles and cytosol in NR8383 and, in particular, it accumulated in the acidic organelle compartments.

CONCLUSIONS

This study suggests that the high accumulation of telithromycin in NR8383 is due to its high influx via active transport systems and trapping in acidic organelles, such as lysosomes. Moreover, this study provides important information for optimizing the treatment of respiratory intracellular parasitic infections based on the intracellular pharmacokinetics of antibiotics and parasitic sites.

In vitro antimycoplasmal activity of six Jordanian medicinal plants against three Mycoplasma species

The in vitro effect of six Jordanian traditional medicine plant methanolic extracts were tested against 32 isolates of Mycoplasma species; Mycoplasma mycoides subsp. mycoides LC (6), Mycoplasma capricolum subsp. capricolum (8) and M. putrefaciens (18), all isolated from either nasal swabs or milk, from sheep and goats in different regions in Jordan. All Mycoplasma species showed susceptibility to Artemisia herba-alba and Artemisia arborescens with MIC ranges from 3.125-12.5 mg/ml. Allium sativum and Punica grantum showed limited activity against some Mycoplasma isolates. Olea europea and Citrullus colocynthis showed no in vitro activity against any of the Mycoplasma species tested. Artemisia herba-alba and Artemisia arborescens may therefore be useful for the treatment of mycoplasma infections.

The in vitro effect of six antimicrobials against Mycoplasma putrefaciens, Mycoplasma mycoides subsp. mycoides LC and Mycoplasma capricolum subsp. capricolum isolated from sheep and goats in Jordan

Respiratory disease in sheep and goats is a major problem in Jordan and is often associated with Mycoplasma species. Without effective vaccines, control is mainly by chemotherapy, but the uncontrolled use of antimicrobials has led to concerns about the potential development of antimicrobial resistance. The in vitro effect of chloramphenicol, florfenicol, enrofloxacin, tylosin, erythromycin and oxytetracycline was determined against 32 isolates of Mycoplasma species-M. mycoides subsp. mycoides LC (6), M. capricolum subsp. capricolum (8) and M. putrefaciens (18), all isolated from either nasal swabs or milk, from sheep and goats in different regions of Jordan. The antimicrobial susceptibility showed some Mycoplasma species-specific differences, with M. capricolum subsp. capricolum being more susceptible to tylosin and erythromycin. Chloramphenicol and florfenicol were the least effective for all three Mycoplasma species. No trends or significant differences in antimicrobial susceptibilities were observed between sheep and goat isolates, between milk or nasal swab isolates, or between isolates from different regions of Jordan. Some isolates of M. capricolum subsp. capricolum and M. putrefaciens showed higher MIC levels with oxytetracycline, as did two isolates of M. mycoides subsp. mycoides LC with tylosin, possibly indicating signs of development of antimicrobial resistance.

The effect of telithromycin in acute exacerbations of asthma

BACKGROUND

We conducted a double-blind, randomized, placebo-controlled study to evaluate the efficacy of telithromycin in patients with acute exacerbations of asthma.

METHODS

A total of 278 adults with diagnosed asthma were enrolled within 24 hours after an acute exacerbation of asthma requiring short-term medical care. The patients were randomly assigned to receive 10 days of oral treatment with telithromycin (at a dose of 800 mg daily) or placebo in addition to usual care. Primary efficacy end points were a change from baseline over the treatment period in symptoms (as recorded by patients in a diary card) and in the peak expiratory flow in the morning at home. The presence of Chlamydophila pneumoniae or Mycoplasma pneumoniae was ascertained by serologic analysis, polymerase chain reaction, and culture.

RESULTS

Of the two prespecified primary outcomes, only asthma symptoms showed a significantly greater reduction among patients receiving telithromycin than among those receiving placebo. Mean (+/-SD) scores on a test of asthma symptoms (on a 7-point scale, with 0 denoting no symptoms and 6 denoting severe symptoms) were 3.0+/-1.4 at baseline and 1.7+/-1.1 at the end of treatment for the telithromycin group and 2.8+/-1.3 at baseline and 2.0+/-1.0 at the end of treatment for the placebo group. The mean decrease in symptom scores during the treatment period was 1.3 for telithromycin and 1.0 for placebo (mean difference, -0.3; 95 percent confidence interval, -0.5 to -0.1; P=0.004). There was no significant treatment effect on the other primary outcome measure, a change in morning peak expiratory flow. Nausea was more common among patients in the telithromycin group than in the placebo group (P=0.01). Although 61 percent of patients had evidence of infection with C. pneumoniae, M. pneumoniae, or both, there was no relationship between bacteriologic status and the response to asthma treatment.

CONCLUSIONS

This study provides evidence of the benefit of telithromycin in patients with acute exacerbations of asthma; the mechanisms of benefit remain unclear. (ClinicalTrials.gov number, NCT00273520.).

Efficacy and safety of telithromycin 800 mg once daily for 7 days in community-acquired pneumonia: an open-label, multicenter study

Background

Community-acquired pneumonia (CAP) remains a major cause of morbidity and mortality throughout the world. Telithromycin (a new ketolide) has shown good in vitro activity against the key causative pathogens of CAP, including S pneumoniae resistant to penicillin and/or macrolides.

Methods

The efficacy and safety of telithromycin 800 mg orally once daily for 7 days in the treatment of CAP were assessed in an open-label, multicenter study of 442 adults.

Results

Of 149 microbiologically evaluable patients, 57 (9 bacteremic) had Streptococcus pneumoniae. Of the 57 S pneumoniae pathogens isolated in these patients, 9 (2 bacteremic) were penicillin- or erythromycin-resistant; all 57 were susceptible to telithromycin and were eradicated. Other pathogens and their eradication rates were: Haemophilus influenzae (96%), Moraxella catarrhalis (100%), Staphylococcus aureus (80%), and Legionella spp. (100%). The overall bacteriologic eradication rate was 91.9%. Of the 357 clinically evaluable patients, clinical cure was achieved in 332 (93%). In the 430 patients evaluable for safety, the most common drug-related adverse events were diarrhea (8.1%) and nausea (5.8%).

Conclusion

Telithromycin 800 mg once daily for 7 days is an effective and well-tolerated oral monotherapy and offers a new treatment option for CAP patients, including those with resistant S pneumoniae.

Telithromycin for the treatment of acute exacerbations of chronic bronchitis

Pooled data from three randomized, double-blind, multi- centre studies evaluated the efficacy and tolerability of telithromycin 800 mg once daily for 5 days vs. standard comparators (10-day amoxicillin-clavulanate 500/125 mg three times daily, clarithromycin 500 mg or cefuroxime axetil 500 mg twice daily) in the outpatient treatment for acute exacerbations of chronic bronchitis. Per-protocol clinical cure rates at post-therapy/test of cure (days 17-24) were 86.0 and 85.8% for telithromycin and comparators, respectively, and 79.1 and 78.7%, respectively, at late post-therapy (days 31-36). Clinical cure rates were comparable for patients at increased risk, including those of > or =65 years and those with severe infection or significant airway obstruction (telithromycin, > or =77.1%; comparators, > or =75.0%). Telithromycin was well tolerated. Most adverse events considered possibly related to study medication were gastrointestinal and of mild intensity. In conclusion, 5-day telithromycin therapy is as effective and well tolerated as 10-day treatment with standard comparators.

Ketolides: an emerging treatment for macrolide-resistant respiratory infections, focusing on S. pneumoniae

Resistance to antibiotics in community acquired respiratory infections is increasing worldwide. Resistance to the macrolides can be class-specific, as in efflux or ribosomal mutations, or, in the case of erythromycin ribosomal methylase (erm)-mediated resistance, may generate cross-resistance to other related classes. The ketolides are a new subclass of macrolides specifically designed to combat macrolide-resistant respiratory pathogens. X-ray crystallography indicates that ketolides bind to a secondary region in domain II of the 23S rRNA subunit, resulting in an improved structure-activity relationship. Telithromycin and cethromycin (formerly ABT-773) are the two most clinically advanced ketolides, exhibiting greater activity towards both typical and atypical respiratory pathogens. As a subclass of macrolides, ketolides demonstrate potent activity against most macrolide-resistant streptococci, including ermB- and macrolide efflux (mef)A-positive Streptococcus pneumoniae. Their pharmacokinetics display a long half-life as well as extensive tissue distribution and uptake into respiratory tissues and fluids, allowing for once-daily dosing. Clinical trials focusing on respiratory infections indicate bacteriological and clinical cure rates similar to comparators, even in patients infected with macrolide-resistant strains.

Telithromycin

Telithromycin, the first member of the ketolide antibacterials, has good activity against community-acquired respiratory pathogens, including multiple-drug-resistant strains of Streptococcus pneumoniae. Telithromycin 800 mg once daily has been US FDA approved for the treatment of acute bacterial sinusitis (ABS; treatment duration 5 days), acute bacterial exacerbations of chronic bronchitis (AECB; 5 days) and mild-to-moderate community-acquired pneumonia (CAP; 7-10 days). In patients with CAP, telithromycin was as effective as amoxicillin 1000 mg three times daily for 10 days, clarithromycin 500 mg twice daily for 10 days or trovafloxacin 200 mg once daily for 7-10 days. In patients with AECB, telithromycin was as effective as a 10-day regimen of amoxicillin/clavulanic acid 500/125 mg three times daily, cefuroxime axetil 500 mg twice daily or clarithromycin 500 mg twice daily. In patients with ABS, telithromycin was as effective as a 10-day course of amoxicillin/clavulanic acid 500/125 mg three times daily or cefuroxime axetil 250 mg twice daily. Telithromycin was generally well tolerated and most adverse events were of mild-to-moderate severity and transitory. The most common adverse events with telithromycin were diarrhoea and nausea (10.8% and 7.9% of 2702 patients in clinical trials); these events occurred in 8.6% and 4.6% of 2139 comparator-treated patients.

In vitro activities of ABT-773 and other antimicrobials against human mycoplasmas

The in vitro susceptibilities of 103 Mycoplasma pneumoniae isolates, 14 Mycoplasma hominis isolates, 12 Mycoplasma fermentans isolates, and 24 Ureaplasma species to ABT-773, an investigational ketolide, and seven other agents were determined. For M. pneumoniae, the ABT-773 MIC at which 90% of isolates are inhibited (MIC(90); <or=0.001 microg/ml) was comparable to those of azithromycin, clarithromycin, and erythromycin and at least 128-fold lower than those of levofloxacin, gatifloxacin, moxifloxacin, and doxycycline. For M. fermentans, the ABT-773 MIC(90) (<or=0.008 microg/ml) was 2- to 128-fold lower than those of all other agents tested. For M. hominis, the ABT-773 MIC(90) (0.031 microg/ml) was equivalent to that of moxifloxacin, 2-fold lower than those of gatifloxacin and clindamycin, and 16-fold lower than that of levofloxacin. ABT-773 was equally active against doxycycline-susceptible and doxycycline-resistant organisms. The ABT-773 MICs (0.016 microg/ml) for Ureaplasma species were the lowest of those of any drug tested. The MIC(90) was 4- to 64-fold lower than those of clarithromycin, azithromycin, and erythromycin and >or=16-fold lower than those of all three fluoroquinolones. Minimal bactericidal concentrations determined for a subgroup of organisms were <or=0.063 micro g/ml for M. pneumoniae and 0.25 microg/ml for M. fermentans, but they were several dilutions higher for M. hominis and Ureaplasma spp. ABT-773 has great potential for further study for the treatment of infections due to mycoplasmas and ureaplasmas.

The ketolides: a critical review

Ketolides are a new class of macrolides designed particularly to combat respiratory tract pathogens that have acquired resistance to macrolides. The ketolides are semi-synthetic derivatives of the 14-membered macrolide erythromycin A, and retain the erythromycin macrolactone ring structure as well as the D-desosamine sugar attached at position 5. The defining characteristic of the ketolides is the removal of the neutral sugar, L-cladinose from the 3 position of the ring and the subsequent oxidation of the 3-hydroxyl to a 3-keto functional group. The ketolides presently under development additionally contain an 11, 12 cyclic carbamate linkage in place of the two hydroxyl groups of erythromycin A and an arylalkyl or an arylallyl chain, imparting in vitro activity equal to or better than the newer macrolides. Telithromycin is the first member of this new class to be approved for clinical use, while ABT-773 is presently in phase III of development. Ketolides have a mechanism of action very similar to erythromycin A from which they have been derived. They potently inhibit protein synthesis by interacting close to the peptidyl transferase site of the bacterial 50S ribosomal subunit. Ketolides bind to ribosomes with higher affinity than macrolides. The ketolides exhibit good activity against Gram-positive aerobes and some Gram-negative aerobes, and have excellent activity against drug-resistant Streptococcus pneumoniae, including macrolide-resistant (mefA and ermB strains of S. pneumoniae). Ketolides such as telithromycin display excellent pharmacokinetics allowing once daily dose administration and extensive tissue distribution relative to serum. Evidence suggests the ketolides are primarily metabolised in the liver and that elimination is by a combination of biliary, hepatic and urinary excretion. Pharmacodynamically, ketolides display an element of concentration dependent killing unlike macrolides which are considered time dependent killers. Clinical trial data are only available for telithromycin and have focused on respiratory infections including community-acquired pneumonia, acute exacerbations of chronic bronchitis, sinusitis and streptococcal pharyngitis. Bacteriological and clinical cure rates have been similar to comparators. Limited data suggest very good eradication of macrolide-resistant and penicillin-resistant S. pneumoniae. As a class, the macrolides are well tolerated and can be used safely. Limited clinical trial data suggest that ketolides have similar safety profiles to the newer macrolides. Telithromycin interacts with the cytochrome P450 enzyme system (specifically CYP 3A4) in a reversible fashion and limited clinically significant drug interactions occur. In summary, clinical trials support the clinical efficacy of the ketolides in upper and lower respiratory tract infections caused by typical and atypical pathogens including strains resistant to penicillins and macrolides. Considerations such as local epidemiology, patterns of resistance and ketolide adverse effects, drug interactions and cost relative to existing agents will define the role of these agents. The addition of the ketolides in the era of antibacterial resistance provides clinicians with more options in the treatment of respiratory infections.

Antibiotic susceptibilities of Parachlamydia acanthamoeba in amoebae

Parachlamydia acanthamoeba are intracellular bacteria of amoebae and are considered potential etiological agents of human pneumonia. We have determined the in vitro antibiotic susceptibilities of two strains (strain Bn(9) and Hall's coccus) in Acanthamoeba polyphaga. The two strains were susceptible to tetracyclines, macrolides, and rifampin, but resistant to fluoroquinolones.

Telithromycin: the first of the ketolides

OBJECTIVE

To review the chemistry, spectrum of activity, pharmacology, clinical efficacy, and safety of telithromycin.

DATA SOURCES

A MEDLINE search from 1966 to December 2000 was performed via OVID and PubMed using the following search terms: HMR 3647, HMR3647, Ketek, RU 66647, and telithromycin. An extensive review of retrieved literature, abstracts from international scientific conferences, and minutes from regulatory authority meetings was also performed.

DATA EXTRACTION

Medicinal chemistry, in vitro, animal, and human trials were reviewed for information on the antimicrobial activity, clinical efficacy, pharmacology, and safety of telithromycin.

DATA SYNTHESIS

Several chemical modifications to the macrolide structure have led to the development of telithromycin, the first ketolide antimicrobial that demonstrates improved activity against penicillin- and macrolide/azalide-resistant Streptococcus pneumoniae due to its unique binding to the ribosomal target site. Although telithromycin may be useful in the treatment of community-acquired respiratory tract infections due to its activity against common typical and atypical pathogens, questions concerning its reliable activity against Haemophilus influenzae need to be addressed. Telithromycin's pharmacokinetics permit once-daily dosing for abbreviated periods and good distribution into lung tissue and phagocytic cells. Clinical and bacteriologic cure rates have been similar to those of comparator agents in human efficacy trials; however, the incidence of adverse gastrointestinal events were generally higher with telithromycin patients. Like other macrolides and many newer fluoroquinolones, telithromycin's ability to prolong the QTc interval is a potential safety issue, especially in elderly patients with predisposing conditions or those who are concurrently receiving drugs that are substrates for CYP2D6 and 3A4. Liver function test elevations demonstrated during clinical trials, although not overtly severe, may warrant monitoring in some patients taking multiple hepatically metabolized/cleared agents.

CONCLUSIONS

Telithromycin offers potential advantages over traditional macrolides/azalides for community-acquired respiratory tract infections caused by macrolide-resistant pathogens. Further studies are needed to elucidate its clinical efficacy against H. influenzae, potential drug interactions, and safety in various subpopulations.

Ketolides in the treatment of respiratory infections

The ketolides are a new class of macrolides specifically designed to combat respiratory tract pathogens that have acquired resistance to macrolides. The ketolides are semi-synthetic derivatives of the 14-membered macrolide erythromycin A. There are currently two ketolides in the late stages of clinical development in the US (telithromycin [HMR-364, Kelek; Aventis] and ABT-773 [Abbot Laboratories]), as well as newer compounds in earlier stages of testing. Ketolides have a mechanism of action very similar to that of erythromycin A. They potently inhibit protein synthesis by interacting close to the peptidyl transferase site of the bacterial 50S ribosomal subunit. Ketolides bind to ribosomes with higher affinity than macrolides. The ketolides exhibit good activity against Gram-positive and some Gram-negative aerobes and have are active against macrolide-resistant Streptococcus species, including most mef A and erm B strains of Streptococcus pneumoniae. Ketolides have pharmacokinetics which allow once-daily dosing and extensive tissue distribution with very high uptake into respiratory tissues and fluids relative to serum. Evidence suggests the ketolides are primarily metabolised by the cytochrome P450 (CYP) enzyme system in the liver and that elimination is a combination of biliary, hepatic and urinary excretion. Clinical trial data are only available for telithromycin and have focused on respiratory tract infections (RTIs) including community-acquired pneumonia (CAP), acute exacerbations of chronic bronchitis (AECB), sinusitis and streptococcal pharyngitis. Bacteriological and clinical cure rates have been similar to comparators. Ketolides have similar safety profiles to the newer macrolides. In summary, early clinical trials support the clinical efficacy of the ketolides in common RTIs, including activity against macrolide-resistant pathogens.

Telithromycin: an oral ketolide for respiratory infections

The ketolides represent a new subclass of antibiotics among the macrolide-lincosamide-streptogramin group. Telithromycin, the first ketolide to be awarded approvable status for clinical use, demonstrates in vitro activity against community-acquired respiratory pathogens including penicillin- and erythromycin-resistant Streptococcus pneumoniae. An extended half-life permits once-daily oral administration. Telithromycin is a substrate for cytochrome P450 (CYP) 3A4 and also inhibits drugs metabolized by CYP3A4. A relatively high frequency of mild-to-moderate gastrointestinal adverse effects has been reported. Similar clinical and microbiologic efficacy has been demonstrated with oral dosing in comparative clinical trials for community-acquired pneumonia, acute sinusitis, acute exacerbations of chronic bronchitis, and pharyngitis. Although limited data on penicillin-resistant S. pneumoniae and erythromycin-resistant Streptococcus pyogenes are available from clinical trials, this drug appears promising for respiratory infections caused by these pathogens.

Susceptibilities of Mycoplasma hominis, M. pneumoniae, and Ureaplasma urealyticum to GAR-936, dalfopristin, dirithromycin, evernimicin, gatifloxacin, linezolid, moxifloxacin, quinupristin-dalfopristin, and telithromycin compared to their susceptibilities to reference macrolides, tetracyclines, and quinolones

The susceptibilities of Mycoplasma hominis, Mycoplasma pneumoniae, and Ureaplasma urealyticum to eight new antimicrobial agents were determined by agar dilution. M. pneumoniae was susceptible to the new glycylcycline GAR-936 at 0.12 microg/ml and evernimicin at 4 microg/ml, but it was resistant to linezolid. It was most susceptible to dirithromycin, quinupristin-dalfopristin, telithromycin, reference macrolides, and josamycin. M. hominis was susceptible to linezolid, evernimicin, and GAR-936. It was resistant to macrolides and the ketolide telithromycin but susceptible to quinupristin-dalfopristin and josamycin. U. urealyticum was susceptible to evernimicin (8 to 16 microg/ml) and resistant to linezolid. It was less susceptible to GAR-936 (4.0 microg/ml) than to tetracycline (0.5 microg/ml). Telithromycin and quinupristin-dalfopristin were the most active agents against ureaplasmas (0.06 microg/ml). The new quinolone gatifloxacin was active against M. pneumoniae and M. hominis at 0.12 to 0.25 microg/ml and active against ureaplasmas at 1.0 microg/ml. The MICs of macrolides were markedly affected by pH, with an 8- to 32-fold increase in the susceptibility of M. pneumoniae as the pH increased from 6.9 to 7.8. A similar increase in susceptibility with increasing pH was also observed with ureaplasmas. Tetracyclines showed a fourfold increase of activity as the pH decreased 1 U, whereas GAR-936 showed a fourfold decrease in activity with a decrease in pH.

Mycoplasma pneumoniae infections

Mycoplasma pneumoniae is a frequent cause of community-acquired respiratory infections in children and adults. Although the organism is felt to be the most frequent 'atypical' pathogen responsible for community-acquired pneumonia in adults, the prevalence of M. pneumoniae varies greatly from study to study, depending on the population and the diagnostic methods used. Recent studies have found the prevalence of M. pneumoniae in adults with pneumonia to range from 1.9 to over 30%. M. pneumoniae is also a frequent cause of outbreaks of respiratory disease in institutional settings. However, the diagnosis of M. pneumoniae infection is hampered by the lack of standardized, rapid, specific methods. This problem was illustrated by the results of an investigation of an outbreak of M. pneumoniae infection in a federal training facility. Accurate diagnosis required a combination of polymerase chain reaction and serology, as IgM antibodies were not present early in the course of the infection in many patients. Several papers evaluating various serological and polymerase chain reaction assays were published during the period of this review. An assessment of the actual performance of these tests was also hampered by the lack of standardized comparative methods. M. pneumoniae is susceptible in vitro to macrolides, tetracyclines and quinolone antibiotics; however, data are limited on the microbiological efficacy of these agents. Several pneumonia treatment studies were published during this period, practically all of them based the diagnosis of M. pneumoniae infection on serology; different methods and criteria were used in each study, and thus the microbiological efficacy could not be assessed. The Infectious Disease Society of America recently stated in their revised Practice Guidelines for the Management of Community-Acquired Pneumonia in Adults that, as there were no diagnostic tests available that reliably and rapidly detect M. pneumoniae, therapy must usually be empirical.