Stephan Kohlhoff

Emergence of Resistance to Rifampin and Rifalazil in Chlamydophila pneumoniae and Chlamydia trachomatis

ABSTRACT Although rifamycins have excellent activity against Chlamydophila pneumoniae and Chlamydia trachomatis in vitro, concerns about the possible development of resistance during therapy have discouraged their use for treatment of chlamydial infections. Rifalazil, a new semisynthetic rifamycin with a long half-life, is the most active antimicrobial against C. pneumoniae and C. trachomatis in vitro, indicating its potential for treatment of acute and chronic C. pneumoniae and C. trachomatis infections. We investigated the effect of serial passage of two C. pneumoniae isolates and two serotypes of C. trachomatis in subinhibitory concentrations of rifalazil and rifampin on the development of phenotypic and genotypic resistance. C. trachomatis developed resistance to both antimicrobials within six passages, with higher level resistance to rifampin (128 to 256 μg/ml) and lower level resistance to rifalazil (0.5 to 1 μg/ml). C. pneumoniae TW-183 developed only low-level resistance to rifampin (0.25 μg/ml) and rifalazil (0.016 μg/ml) after 12 passages. C. pneumoniae CWL-029 failed to develop resistance to either drug. Two unique mutations emerged in the rpoB gene of rifampin (L456I) and rifalazil (D461E)-resistant C. pneumoniae TW-183. A single mutation (H471Y) was detected in both rifampin- and rifalazil-resistant C. trachomatis UW-3/Cx/D, and a unique mutation (V136F) was found in rifalazil-resistant BU-434/L2. No mutations were detected in the entire rpoB gene of rifampin-resistant BU-434/L2. This is the first description of antibiotic resistance-associated mutations in C. pneumoniae and of rifampin resistance in C. trachomatis not associated with mutations in the rpoB gene.

In vitro activity of CEM-101, a new fluoroketolide antibiotic, against Chlamydia trachomatis and Chlamydia (Chlamydophila) pneumoniae.

ABSTRACT The in vitro activities of CEM-101, telithromycin, azithromycin, clarithromycin, and doxycycline against 10 isolates each of Chlamydia trachomatis and Chlamydia (Chlamydophila) pneumoniae were tested. The MIC at which 90% of the isolates of both C. trachomatis and C. pneumoniae were inhibited and the minimal bactericidal concentration at which 90% of the isolates were killed by CEM-101 were 0.25 μg/ml (ranges, 0.125 to 0.5 μg/ml for C. trachomatis and 0.25 to 1.0 μg/ml for C. pneumoniae).

Infection with Simkania negevensis in Brooklyn, New York.

Background: Simkania negevensis is a Chlamydia-like intracellular organism that is prevalent in populations from a wide range of geographic areas. The role of the organism in respiratory disease in the United States is unknown. Objective: To study the association between infection with S. negevensis and bronchiolitis, pneumonia or asthma in Brooklyn, New York. Materials and Methods: Pediatric and adult inpatients/outpatients with bronchiolitis, pneumonia or asthma were recruited, and a similar number of healthy control subjects were enrolled. Nasopharyngeal swabs were obtained for culture of S. negevensis and Chlamydia pneumoniae and polymerase chain reaction detection of S. negevensis. Sera were obtained for measurement of antibodies to S. negevensis and C. pneumoniae. Results: One hundred eighty-eight patients and 110 healthy control subjects were enrolled. S. negevensis serologic assays were positive for 18% of patients, compared with 29% of control subjects (P = 0.09). S. negevensis DNA was detected by PCR for 17% of case subjects and 23% of control subjects (P = 0.25). S. negevensis was isolated by culture for 1 patient with bronchiolitis. C. pneumoniae IgG and S. negevensis IgG were found to increase with increasing age, ie, 14%, 50% and 78% (C. pneumoniae) and 13%, 17% and 33% (S. negevensis) for subjects 0–18 months, 18 months–18 years and older than 18 years of age, respectively. Conclusion: S. negevensis was not a significant respiratory pathogen in Brooklyn, NY, during the period of the study.

Treatment of chlamydial infections: 2014 update

Introduction: Chlamydiae are obligate intracellular bacterial pathogens whose entry into mucosal epithelial cells is required for intracellular survival and subsequent growth. The life cycle of Chlamydia spp. and the ability to cause persistent, often subclinical infection, has major ramifications for diagnosis and treatment of Chlamydia trachomatis and C. pneumoniae infections in humans. Areas covered: This paper reviews the current literature on the antimicrobial susceptibilities and treatment of genital infections due to C. trachomatis and respiratory infections due to C. pneumoniae published since 2011. Expert opinion: Chlamydiae are susceptible to antibiotics that interfere with DNA and protein synthesis, including tetracyclines, macrolides and quinolones, which are the compounds that have been most extensively studied and used for treatment of human infection. Since our original review was published in 2011, there have been some major advances in diagnostic tests for C. trachomatis and the introduction of the first FDA-approved test for the detection of C. pneumoniae in respiratory samples. However, the options for treating chlamydial infections have largely remained the same. There are a small number of new drugs currently in preclinical development and early clinical trials that may have a role in the treatment of chlamydial infections.

Treatment of chlamydial infections.

Introduction: Chlamydiae are obligate intracellular bacterial pathogens whose entry into mucosal epithelial cells is required for intracellular survival and subsequent growth. The life cycle of Chlamydia spp. and the ability to cause persistent, often subclinical infection, has major ramifications for diagnosis and treatment of C. trachomatis and C. pneumoniae infections in humans. Areas covered: This up-to-date review describes the current state of knowledge of antimicrobial susceptibilities and treatment of genital infections due to C. trachomatis and respiratory infections due to C. pneumoniae. Expert opinion: Chlamydiae are susceptible to antibiotics that interfere with DNA and protein synthesis, including tetracyclines, macrolides and quinolones, which are the compounds that have been most extensively studied and used for treatment of human infection. Treatment of individuals with C. trachomatis genital infection prevents sexual transmission and complications, including pelvic inflammatory disease. Treatment of pregnant women will prevent the transmission of infection to infants during delivery. The benefits of treatment of respiratory infections due to C. pneumoniae are more difficult to assess, primarily because of the lack of FDA-approved, specific diagnostic tests for detection of the organism in clinical samples. The majority of published studies have relied on serology for diagnosis, making it difficult to assess microbiologic efficacy.

Asthmatic children have increased specific anti-Mycoplasma pneumoniae IgM but not IgG or IgE-values independent of history of respiratory tract infection.

Background: Bronchial asthma is exacerbated by Mycoplasma pneumoniae–induced upper respiratory tract infections (URTIs) in children. Specific IgM and IgG isotypes are involved in the immune response to M. pneumoniae, but little is known about the role of specific IgE antibodies against M. pneumoniae in asthma. Objective: To investigate the role of IgM-, IgG- and IgE-specific antibody responses to M. pneumoniae in children with persistent asthma in relationship to history of URTI within the past 6 months. Methods: Total or specific anti–M. pneumoniae IgM, IgG and IgE antibody responses were studied in stable asthmatic pediatric patients (M. pneumoniae positive and negative) without current exacerbation and nonasthmatic controls (N = 23 and 13, respectively) (UniCAP total IgE Fluoroenzymeimmunoassay, enzyme-linked immunosorbent assay). Results: Values of specific IgM correlated with specific IgG (Spearman correlation, rho = 0.61, P < 0.0001) but not with specific IgE anti–M. pneumoniae antibodies (AMA) in asthmatic subjects compared with nonasthmatic controls. However, concentrations of specific IgG correlated with specific IgE AMA (rho = 0.49, P = 0.0017). Asthmatic subjects had higher levels of specific IgM AMA levels compared with nonasthmatics (median [interquartile range]: 0.57 [1.00] versus 0.21 [0.19]; Kruskal–Wallis test, P = 0.0008). In addition, IgM positivity was significantly higher in asthmatic compared with nonasthmatic subjects (39.1% versus 0.0%; Fisher’s exact test, P = 0.01). These results were independent of URTI history in the past 6 months, which was not associated with higher IgM, IgG or IgE AMA levels compared with no URTI history (P = 0.25–0.64). Conclusions: Increased specific IgM anti–M. pneumoniae responses may indicate an important role for M. pneumoniae infection in asthma.

Disaster preparedness: hospital decontamination and the pediatric patient--guidelines for hospitals and emergency planners.

In recent years, attention has been given to disaster preparedness for first responders and first receivers (hospitals). One such focus involves the decontamination of individuals who have fallen victim to a chemical agent from an attack or an accident involving hazardous materials. Children often are overlooked in disaster planning. Children are vulnerable and have specific medical and psychological requirements. There is a need to develop specific protocols to address pediatric patients who require decontamination at the entrance of hospital emergency departments. Currently, there are no published resources that meet this need. An expert panel convened by the New York City Department of Health and Mental Hygiene developed policies and procedures for the decontamination of pediatric patients. The panel was comprised of experts from a variety of medical and psychosocial areas. Using an iterative process, the panel created guidelines that were approved by the stakeholders and are presented in this paper. These guidelines must be utilized, studied, and modified to increase the likelihood that they will work during an emergency situation.

Isolation and Antimicrobial Susceptibilities of Chlamydial Isolates from Western Barred Bandicoots

ABSTRACT A range of species of Chlamydiales have previously been detected in a variety of Australian marsupials, including koalas and western barred bandicoots. Thirty-seven ocular, urogenital, or nasal swabs were obtained from 21 wild western barred bandicoots. Chlamydia culture and antibiotic susceptibility testing were performed for cycloheximide-treated HEp-2 cells in 96-well microtiter plates. Chlamydia spp. were isolated from 11 specimens from 9 (42.8%) bandicoots. All isolates were identified as Chlamydiales by conventional PCR with 16S and 23S rRNA gene primers specific to Chlamydiales and were confirmed to be Chlamydia pneumoniae by a C. pneumoniae-specific ompA-based real-time PCR assay and 16S rRNA and 23S rRNA gene signature sequence analyses. The MICs of azithromycin, doxycycline, ciprofloxacin, and enrofloxacin for 10 C. pneumoniae isolates from these bandicoots ranged from 0.015 to 1 μg/ml, 0.25 to 1 μg/ml, 0.25 to 2 μg/ml, and 0.25 to 0.5 μg/ml, respectively. The MICs at which 90% of isolates were inhibited and the minimal bactericidal concentrations were within the ranges reported previously for human isolates of C. pneumoniae.

In Vitro Activity of Nemonoxacin, a Novel Nonfluorinated Quinolone Antibiotic, against Chlamydia trachomatis and Chlamydia pneumoniae

ABSTRACT The in vitro activities of nemonoxacin, levofloxacin, azithromycin, and doxycycline were tested against 10 isolates each of Chlamydia trachomatis and Chlamydia pneumoniae. The MICs at which 90% of the isolates of both C. trachomatis and C. pneumoniae were inhibited (MIC90s) were 0.06 μg/ml (range, 0.03 to 0.13 μg/ml). The minimal bactericidal concentrations at which 90% of the isolates were killed by nemonoxacin (MBC90s) were 0.06 μg/ml for C. trachomatis (range, 0.03 to 0.125 μg/ml) and 0.25 for C. pneumoniae (range, 0.015 to 0.5 μg/ml).

In vitro activity of AZD0914, a novel DNA gyrase inhibitor, against Chlamydia trachomatis and Chlamydia pneumoniae.

ABSTRACT The in vitro activities of AZD0914, levofloxacin, azithromycin, and doxycycline against 10 isolates each of Chlamydia trachomatis and Chlamydia pneumoniae were tested. For AZD0914, the MIC90s for C. trachomatis and C. pneumoniae were 0.25 μg/ml (range, 0.06 to 0.5 μg/ml) and 1 μg/ml (range, 0.25 to 1 μg/ml), respectively, and the minimal bactericidal concentrations at which 90% of the isolates were killed (MBC90s) were 0.5 μg/ml for C. trachomatis (range, 0.125 to 1 μg/ml) and 2 μg/ml for C. pneumoniae (range, 0.5 to 2 μg/ml).