Characterization of a Moraxella species that causes epistaxis in macaques.

Bacteria of the genus Moraxella have been isolated from a variety of mammalian hosts. In a prior survey of bacteria that colonize the rhesus macaque nasopharynx, performed at the Tulane National Primate Research Center, organisms of the Moraxella genus were isolated from animals with epistaxis, or "bloody nose syndrome." They were biochemically identified as Moraxella catarrhalis, and cryopreserved. Another isolate was obtained from an epistatic cynomolgus macaque at the U.S. Army Medical Research Institute of Infectious Diseases. Based on differences in colony and cell morphologies between rhesus and human M. catarrhalis isolates, we hypothesized that the nonhuman primate Moraxella might instead be a different species. Despite morphological differences, the rhesus isolates, by several biochemical tests, were indistinguishable from M. catarrhalis. Analysis of the cynomolgus isolate by Vitek 2 Compact indicated that it belonged to a Moraxella group, but could not differentiate among species. However, sequencing of the 16S ribosomal RNA gene from four representative rhesus isolates and the cynomolgus isolate showed closest homology to Moraxella lincolnii, a human respiratory tract inhabitant, with 90.16% identity. To examine rhesus macaques as potential hosts for M. catarrhalis, eight animals were inoculated with human M. catarrhalis isolates. Only one of the animals was colonized and showed disease, whereas four of four macaques became epistatic after inoculation with the rhesus Moraxella isolate. The nasopharyngeal isolates in this study appear uniquely adapted to a macaque host and, though they share many of the phenotypic characteristics of M. catarrhalis, appear to form a genotypically distinct species.

Alterations in cytokines and effects of dexamethasone immunosuppression during subclinical infections of invasive Klebsiella pneumoniae with hypermucoviscosity phenotype in rhesus (Macaca mulatta) and cynomolgus (Macaca fascicularis) macaques.

Invasive Klebsiella pneumoniae with the hypermucoviscosity phenotype (HMV K. pneumoniae) is an emerging human pathogen that also has been attributed to fatal multisystemic disease in African green monkeys at our institution. Combining a cluster of subclinically infected macaques identified in March and April 2008 and the animals documented during a subsequent survey of more than 300 colony nonhuman primates yielded a total of 9 rhesus macaques and 6 cynomolgus macaques that were subclinically infected. In an attempt to propagate the responsible HMV K. pneumoniae strain, a subset of these animals was immunosuppressed with dexamethasone. None of the treated animals developed clinical disease consistent with the multisystemic disease that affected colony African green monkeys. However, cytokine analysis revealed significant alterations of secreted cytokines in macaques subclinically infected with HMV K. pneumoniae when compared with noninfected macaques, thereby calling into question the suitability of animals subclinically infected with HMV K. pneumoniae for use in immunologic or infectious disease research.

Epidemiology of invasive Klebsiella pneumoniae with hypermucoviscosity phenotype in a research colony of nonhuman primates.

Invasive Klebsiella pneumoniae with hypermucoviscosity phenotype (HMV K. pneumoniae) is an emerging human pathogen that, over the past 20 y, has resulted in a distinct clinical syndrome characterized by pyogenic liver abscesses sometimes complicated by bacteremia, meningitis, and endophthalmitis. Infections occur predominantly in Taiwan and other Asian countries, but HMV K. pneumoniae is considered an emerging infectious disease in the United States and other Western countries. In 2005, fatal multisystemic disease was attributed to HMV K. pneumoniae in African green monkeys (AGM) at our institution. After identification of a cluster of subclinically infected macaques in March and April 2008, screening of all colony nonhuman primates by oropharyngeal and rectal culture revealed 19 subclinically infected rhesus and cynomolgus macaques. PCR testing for 2 genes associated with HMV K. pneumoniae, rmpA and magA, suggested genetic variability in the samples. Random amplified polymorphic DNA analysis on a subset of clinical isolates confirmed a high degree of genetic diversity between the samples. Environmental testing did not reveal evidence of aerosol or droplet transmission of the organism in housing areas. Further research is needed to characterize HMV K. pneumoniae, particularly with regard to genetic differences among bacterial strains and their relationship to human disease and to the apparent susceptibility of AGM to this organism.

Rapid real-time PCR assays for detection of Klebsiella pneumoniae with the rmpA or magA genes associated with the hypermucoviscosity phenotype: screening of nonhuman primates.

The relationship of mucoviscosity-associated (magA) and/or regulator of mucoid phenotype (rmpA) genes to the Klebsiella pneumoniae hypermucoviscosity (HMV) phenotype has been reported. We previously demonstrated that rmpA+ K. pneumoniae can cause serious disease in African green monkeys and isolated rmpA+ and magA+ HMV K. pneumoniae from other species of non-human primates. To rapidly screen African green monkeys/non-human primates for these infections, we developed three real-time PCR assays. The first was K. pneumoniae-specific, targeting the khe gene, while the others targeted rmpA and magA. Primer Express 2 was used with the three K. pneumoniae genes to generate sequence-specific TaqMan/TaqMan-Minor Groove Binder assays. Oral/rectal swabs and necropsy samples were collected; swabs were used for routine culture and DNA extraction. K. pneumoniae colonies were identified on the Vitek 2 with DNA tested using the K. pneumoniae-specific assays. Testing of 45 African green monkeys resulted in 19 khe+ samples from 14 animals with none positive for either rmpA or magA. Of these 19 khe+ samples, five were culture-positive, but none were HMV "string test"-positive. Subsequent testing of 307 non-human primates resulted in 64 HMV K. pneumoniae isolates of which 42 were rmpA+ and 15 were magA+. Non-human primate testing at the U.S. Army Medical Research Institute of Infectious Diseases demonstrated the ability to screen both live and necropsied animals for K. pneumoniae by culture and real-time PCR to determine HMV genotype.

Ertapenem susceptibility of extended spectrum beta-lactamase-producing organisms.

BACKGROUND: Infections caused by multiply drug resistant organisms such as extended spectrum beta-lactamase (ESBL)-producing Escherichia coli and Klebsiella pneumoniae are increasing. Carbapenems (imipenem and meropenem) are the antibiotics commonly used to treat these agents. There is limited clinical data regarding the efficacy of the newest carbapenem, ertapenem, against these organisms. Ertapenem susceptibility of ESBL-producing E. coli and K. pneumoniae clinical isolates were evaluated and compared to imipenem to determine if imipenem susceptibility could be used as a surrogate for ertapenem susceptibility. METHODS: 100 ESBL isolates (n = 34 E. coli and n = 66 K. pneumoniae) collected from 2005-2006 clinical specimens at WRAMC were identified and tested for susceptibility by Vitek Legacy [bioMerieux, Durham, NC]. Ertapenem susceptibility was performed via epsilometer test (E-test) [AB Biodisk, Solna, Sweden]. RESULTS: 100% of ESBL isolates tested were susceptible to ertapenem. 100% of the same isolates were also susceptible to imipenem. CONCLUSION: These results, based on 100% susceptibility, suggest that ertapenem may be an alternative to other carbapenems for the treatment of infections caused by ESBL-producing E. coli and K. pneumoniae. Clinical outcomes studies are needed to determine if ertapenem is effective for the treatment of infection caused by these organisms. However, due to lack of resistant isolates, we are unable to conclude whether imipenem susceptibility accurately predicts ertapenem susceptibility.