Ochrobactrum anthropi bacteremia in pediatric oncology patients

The Genus Ochrobactrum as Major Opportunistic Pathogens

Ochrobactrum species are non-enteric, Gram-negative organisms that are closely related to the genus Brucella. Since the designation of the genus in 1988, several distinct species have now been characterised and implicated as opportunistic pathogens in multiple outbreaks. Here, we examine the genus, its members, diagnostic tools used for identification, data from recent Ochrobactrum whole genome sequencing and the pathogenicity associated with reported Ochrobactrum infections. This review identified 128 instances of Ochrobactrum spp. infections that have been discussed in the literature. These findings indicate that infection review programs should consider investigation of possible Ochrobactrum spp. outbreaks if these bacteria are clinically isolated in more than one patient and that Ochrobactrum spp. are more important pathogens than previously thought.

Bacterial isolation from internal organs of rats (Rattus rattus) captured in Baghdad city of Iraq

Aim

Rats are accused in disseminating many zoonotic diseases. This study aimed to isolate and identify bacteria from internal organs of rats captured in Baghdad City, Iraq.

Materials and Methods

A total of 120 black rats (R. rattus) were trapped from different areas in Baghdad city. Rats were kept in individual plastic cages for 3 h before euthanizing. Deep pharyngeal swab, intestinal content, urine, and pieces of the liver and spleen, lung, kidney, and brain were obtained aseptically. The specimens were inoculated into peptone water and incubated at 37°C for 24 h for enrichment. A loopful of each specimen was then subcultured onto MacConkey Agar, Blood Agar, and Mannitol Salt Agar. CHROMagar O157 H7 and CHROMagar Listeria were used to detect Escherichia coli 157:7 and Listeria spp., respectively. Biochemical tests on analytical profile index, microscopic examination, and commercial kit for latex agglutination test for serotyping E. coli O157:H7 were used.

Results

Mixed bacterial isolates were recorded as 116, 52, 36, 28, 18, 6, and 4 from intestinal contents, deep pharyngeal, liver and spleen, urine, lung, brain, and kidney, respectively. Microorganisms included E. coli, Staphylococcus aureus, Streptococcus spp., Bacillus spp., Pseudomonas aeruginosa, Citrobacter freundii, Proteus vulgaris, E. coli O157:H7, Enterobacter cloacae, Listeria spp., Klebsiella spp., Ochrobactrum anthropi, Aeromonas spp., Brucella spp., Pseudomonas fluorescens, Escherichia fergusonii, Micrococcus spp., Morganella spp., Proteus mirabilis, Pseudomonas luteola, and Streptobacillus spp. The highest bacterial prevalence (88; 73.33%) was recorded for E. coli, where 68 isolates were identified from the intestinal contents. Of these, four isolates were E. coli O157:H7.

Conclusion

Rats are important carriers and transmitters of a number of pathogens and can disseminate these microorganisms to humans and animals.

Clinical characteristics of patients with Ochrobactrum anthropi bloodstream infection in a Chinese tertiary-care hospital: A 7-year study

BACKGROUND

Ochrobactrum anthropi has become an emerging pathogen for bloodstream infection (BSI).

METHODS

From January 1st 2010 to June 30th 2017, inpatients with one or more blood cultures positive for O. anthropi isolates at Chinese People's Liberation Army General Hospital in Beijing, China, were enrolled in this study. Clinical and laboratory data were collected by reviewing electronic records.

RESULTS

A total of 11 patients with O. anthropi BSI were identified, of which 10 patients survived. There were 6 males and 5 females, whose age ranged from 2 to 83 years. 7 infections were hospital-acquired. In 8 cases O. anthropi was the only pathogen. The most common symptoms of O. anthropi BSI were fever (100%) and disorders of consciousness (45.5%). All patients had undergone indwelling catheter placement. O. anthropi isolates in this study were most susceptible to levofloxacin (100%), ciprofloxacin (85.7%), imipenem (85.7%) and cotrimoxazole (85.7%), while they were widely resistant to penicillins and cephalosporins.

CONCLUSIONS

O. anthropi BSI usually happens in patients with indwelling catheters, and often begins with no distinctive symptom or laboratory finding. O. anthropi seldom form polymicrobial BSIs. Quinolones and carbapenems are optimal antibiotics for O. anthropi BSI. Catheter removal is essential when O. anthropi BSI happens recurrently.

Brucella vertebral osteomyelitis misidentified as an Ochrobactrum anthropi infection

Ochrobactrum anthropi is a Gram-negative bacillus widely distributed in nature. It is a low virulence and low pathogenic microorganism and human infection by this agent is considered rare. This microorganism can cause bacteremia and in some cases can lead to osteomyelitis and endocarditis. Included in Brucellaceae family, this bacterium is phenotypically and genetically closely related to the Brucella genus and may be misidentified by rapid identification systems. The authors describe a patient admitted to the Infectious Diseases Department with vertebral osteomyelitis initially identified as Ochrobactrum anthropi. Despite appropriate antimicrobial therapy, the blood cultures remained positive and there were no signs of clinical improvement. This raised suspicion of a possible misidentification. It was decided to initiate antimicrobial therapy to include the Brucella genus, with slow but progressive clinical improvement. Samples were sent to Instituto Nacional de Saúde Doutor Ricardo Jorge (INSA) for genotyping, confirming the initial suspicion of misidentification and identifying Brucella melitensis as the causal agent. Timely diagnosis of brucellosis is essential for the correct management and prevention of its consequences for the patient and for safe handling of the laboratory samples, preventing laboratory-acquired infection.

Lessons from mother: Long-term impact of antibodies in breast milk on the gut microbiota and intestinal immune system of breastfed offspring

From birth to adulthood, the gut microbiota matures from a simple community dominated by a few major bacterial groups into a highly diverse ecosystem that provides both benefits and challenges to the host. Currently there is great interest in identifying environmental and host factors that shape the development of our gut microbiota. Breast milk is a rich source of maternal antibodies, which provide the first source of adaptive immunity in the newborn's intestinal tract. In this addendum, we summarize our recent data demonstrating that maternal antibodies in breast milk promote long-term intestinal homeostasis in suckling mice by regulating the gut microbiota and host gene expression. We also discuss important unanswered questions, future directions for research in this field, and implications for human health and disease.

Late-onset Ochrobactrum anthropi sepsis in a preterm neonate with congenital urinary tract abnormalities

Recent trends in late-onset neonatal sepsis have revealed an increase in Gram-negative organisms as causative agents. Ochrobactrum anthropi is an emerging human pathogen that has been reported primarily in immunocompromised hosts, especially those with indwelling catheters or other medical devices. We report the occurrence of late-onset urosepsis secondary to O. anthropi in a preterm neonate with posterior urethral valves and review the salient features of the pathogen and its management.

Cooperativity among secretory IgA, the polymeric immunoglobulin receptor, and the gut microbiota promotes host-microbial mutualism

Secretory IgA (SIgA) antibodies in the intestinal tract form the first line of antigen-specific immune defense, preventing access of pathogens as well as commensal microbes to the body proper. SIgA is transported into external secretions by the polymeric immunoglobulin receptor (pIgR). Evidence is reported here that the gut microbiota regulates production of SIgA and pIgR, which act together to regulate the composition and activity of the microbiota. SIgA in the intestinal mucus layer helps to maintain spatial segregation between the microbiota and the epithelial surface without compromising the metabolic activity of the microbes. Products shed by members of the microbial community promote production of SIgA and pIgR by activating pattern recognition receptors on host epithelial and immune cells. Maternal SIgA in breast milk provides protection to newborn mammals until the developing intestinal immune system begins to produce its own SIgA. Disruption of the SIgA-pIgR-microbial triad can increase the risk of infectious, allergic and inflammatory diseases of the intestine.

Secretory antibodies in breast milk promote long-term intestinal homeostasis by regulating the gut microbiota and host gene expression

Maintenance of intestinal homeostasis requires a healthy relationship between the commensal gut microbiota and the host immune system. Breast milk supplies the first source of antigen-specific immune protection in the gastrointestinal tract of suckling mammals, in the form of secretory IgA (SIgA). SIgA is transported across glandular and mucosal epithelial cells into external secretions by the polymeric Ig receptor (pIgR). Here, a breeding scheme with polymeric Ig receptor-sufficient and -deficient mice was used to study the effects of breast milk-derived SIgA on development of the gut microbiota and host intestinal immunity. Early exposure to maternal SIgA prevented the translocation of aerobic bacteria from the neonatal gut into draining lymph nodes, including the opportunistic pathogen Ochrobactrum anthropi. By the age of weaning, mice that received maternal SIgA in breast milk had a significantly different gut microbiota from mice that did not receive SIgA, and these differences were magnified when the mice reached adulthood. Early exposure to SIgA in breast milk resulted in a pattern of intestinal epithelial cell gene expression in adult mice that differed from that of mice that were not exposed to passive SIgA, including genes associated with intestinal inflammatory diseases in humans. Maternal SIgA was also found to ameliorate colonic damage caused by the epithelial-disrupting agent dextran sulfate sodium. These findings reveal unique mechanisms through which SIgA in breast milk may promote lifelong intestinal homeostasis, and provide additional evidence for the benefits of breastfeeding.

Clinical characteristics of Ochrobactrum anthropi bacteremia

The clinical picture of Ochrobactrum anthropi infection is not well described because the infection is rare in humans and identification of the pathogen is difficult. We present a case of O. anthropi bacteremia that was initially misidentified as Ralstonia paucula and later identified by 16S rRNA sequencing and recA analysis.

Ribosomal RNA sequence analysis of Brucella infection misidentified as Ochrobactrum anthropi infection

A Brucella isolate was identified from purulent material collected during a hip surgery. Two previous blood cultures from the same patient yielded Ochrobactrum anthropi. After rRNA sequencing, all the isolates were identified as Brucella species and subsequently serotyped as Brucella suis. Misidentification of Brucella species remains a problem with bacterial identification systems.

The differential interaction of Brucella and ochrobactrum with innate immunity reveals traits related to the evolution of stealthy pathogens

Background

During evolution, innate immunity has been tuned to recognize pathogen-associated molecular patterns. However, some α-Proteobacteria are stealthy intracellular pathogens not readily detected by this system. Brucella members follow this strategy and are highly virulent, but other Brucellaceae like Ochrobactrum are rhizosphere inhabitants and only opportunistic pathogens. To gain insight into the emergence of the stealthy strategy, we compared these two phylogenetically close but biologically divergent bacteria.

Methodology/Principal Findings

In contrast to Brucella abortus, Ochrobactrum anthropi did not replicate within professional and non-professional phagocytes and, whereas neutrophils had a limited action on B. abortus, they were essential to control O. anthropi infections. O. anthropi triggered proinflammatory responses markedly lower than Salmonella enterica but higher than B. abortus. In macrophages and dendritic cells, the corresponding lipopolysaccharides reproduced these grades of activation, and binding of O. anthropi lipopolysaccharide to the TLR4 co-receptor MD-2 and NF-κB induction laid between those of B. abortus and enteric bacteria lipopolysaccharides. These differences correlate with reported variations in lipopolysaccharide core sugars, sensitivity to bactericidal peptides and outer membrane permeability.

Conclusions/Significance

The results suggest that Brucellaceae ancestors carried molecules not readily recognized by innate immunity, so that non-drastic variations led to the emergence of stealthy intracellular parasites. They also suggest that some critical envelope properties, like selective permeability, are profoundly altered upon modification of pathogen-associated molecular patterns, and that this represents a further adaptation to the host. It is proposed that this adaptive trend is relevant in other intracellular α-Proteobacteria like Bartonella, Rickettsia, Anaplasma, Ehrlichia and Wolbachia.

Ochrobactrum anthropi bacteremia in a preterm infant with meconium peritonitis

Ochrobactrum anthropi is a non-fermenting gram-negative rod that was identified as a pathogenic microorganism during the past decade. O. anthropi is extensively distributed in the environment, and has been found in hospital and environmental water sources. O. anthropi infection is rare in childhood. We report a case of O. anthropi bacteremia in a preterm infant with a peritoneal lavage catheter and meconium peritonitis.

Identification and antimicrobial susceptibilities of Ochrobactrum spp

Ochrobactrum (O.) anthropi is an opportunistic emerging pathogen closely related to the genus Brucella. Identification and differentiation from brucellae and other Ochrobactrum spp. using routine biochemical test systems is not reliable due to the high phenotypic similarity. In this study, antibiotic susceptibilities of 103 Ochrobactrum isolates were determined using Etest for 19 clinically relevant antimicrobial agents. Ochrobactrum strains were highly resistant to beta-lactam antibiotics, susceptible to ciprofloxacin, and 97.1% were susceptible to trimethoprim/sulfamethoxazole. It was also demonstrated that biochemical reaction profiles of the API and BD Phoenix 100 systems for identifying Ochrobactrum isolates can only be used on the genus level. Our in vitro data suggest that combinations of antimicrobial agents including ciprofloxacin and/or trimethoprim/sulfamethoxazole may be useful for empirical treatment of Ochrobactrum infections.

Genetic diversity and phylogenetic relationships of bacteria belonging to the Ochrobactrum-Brucella group by recA and 16S rRNA gene-based comparative sequence analysis

The genetic diversity and phylogenetic interrelationships among 106 Ochrobactrum strains (O. anthropi: 72, O. intermedium: 22, O. tritici: 5, O. oryzae: 2, O. grignonense: 2, O. gallinifaecis: 1, O. lupini: 2), the type strains of the eight Brucella species and other closely related taxa were studied by recA and rrs gene (16S rRNA) comparative sequence analysis. Both markers correctly delineated the various Ochrobactrum species; however, resolution at the subspecies level was considerably higher in the recA gene-based approach. Phylogenetic analyses using neighbor-joining, parsimony, and maximum likelihood algorithms generated trees with similar topologies but the overall branching order, and also the order of the subclades, were not stable in either assay, which could be explained by generally high recA and rrs sequence similarities. Ochrobactrum and Pseudochrobactrum formed separate clades distinct from other Alphaproteobacteria with Bartonella, Agrobacterium, and Rhizobium as the closest relatives. O. gallinifaecis was the most distinct member, when compared to the type species O. anthropi, with rrs and recA similarities of 96.2% and 81.4%. Brucella species were indistinguishable, exhibiting high rrs and recA gene similarities of 98.6% and 85.5% compared with Ochrobactrum intermedium. At the protein level, all RecA sequences among the various Ochrobactrum species and between Ochrobactrum and Brucella were highly similar with only a few amino acid substitutions. O. anthropi and O. tritici were indistinguishable by means of their RecA proteins. A set of initially biochemically classified strains did not cluster within their assigned species and they either grouped within other known species or grouped as potential novel Ochrobactrum species. In further investigations, these strains were reclassified and described as novel species. In summary, Ochrobactrum is a highly diverse genus comprising several novel species. We recommend recA- in addition to rrs gene-analysis for correct species allocation and subtyping of novel Ochrobactrum isolates.

Microbiological quality of indoor and outdoor swimming pools in Greece: investigation of the antibiotic resistance of the bacterial isolates

During 1997-2005, the microbiological quality and susceptibility of bacterial isolates of swimming pool waters were investigated. A total of 462 water samples were collected from three indoor swimming pools (a teaching pool, a competition public pool, a hydrotherapy pool) and two outdoor swimming pools (a hotel semi-public and a residential private pool) in Northwestern Greece. All water samples were analyzed for the presence of bacteria, protozoa and fungi and susceptibility tests were performed for the bacterial isolates. Sixty-seven percent of the examined water samples conformed to the microbiological standards and 32.9% exceeded at least one of the indicated limits. Out of 107 bacterial isolates, 38 (35.5%) resistant strains were detected. Multi-resistant Pseudomonas alcaligenes, Leuconostoc, and Staphylococcus aureus (isolated from the teaching pool), Staphylococcus wernerii, Chryseobacterium indologenes and Ochrobactrum anthropi (isolated from the competition pool), Pseudomonas aeruginosa, P. fluorescens, Aeromonas hydrophila, Enterobacter cloacae, Klebsiella pneumoniae and S. aureus (isolated from the hydrotherapy pool) and A. hydrophila (isolated from the hotel pool) were detected. The swimming pool with the poorest microbiological quality (THC 500 cfu/ml in 12.1% of the samples, P. aeruginosa counts 1500 cfu/100 ml in 6% of the samples) and the highest prevalence of multi-resistant isolates (73.6%) was the hydrotherapy pool. No Cryptosporidium or Giardia cysts and no Legionella, Mycobacteria and Salmonella were detected, but there were isolations of Candida albicans, Aspergillus spp., Mucor spp., Alternaria spp., Rhizopus spp., Trichophyton spp., and Penicillium spp.

Ochrobactrum anthropi bacteremia in a child with inborn error of mitochondrial fatty acid oxidation

OBJECTIVE

To report an incident of bacteremia caused by Ochrobactrum anthropi.

CASE PRESENTATION AND INTERVENTION

The case of a female child aged 2 years and 10 months with a known history of long-chain 3-hydroxyacyl-coenzyme A dehydrogenase deficiency who developed O. anthropi bacteremia during hospital stay is presented. Patient's history, clinical findings, laboratory and radiological investigations were thoroughly reviewed. The cultured organism was identified using MicroScan WalkAway 96 SI (Dade Behring) as well as by conventional techniques. Imipenem resistance was confirmed by the conventional Kirby-Bauer disk diffusion technique on Muller-Hinton agar with no zone of inhibition around a 10-mug imipenem disk (Hi Media) using the 0.5 McFarland standard.

CONCLUSION

This report shows O. anthropi as a rare nosocomial pathogen that affected a patient who was immunocompromised. The O. anthropi showed multidrug resistance.

Genotyping of Ochrobactrum anthropi by recA-based comparative sequence, PCR-RFLP, and 16S rRNA gene analysis

A recA-PCR restriction fragment length polymorphism assay was developed to study intraspecies variation among Ochrobactrum anthropi. Primers deduced from the known recA gene sequence of the genetically closely related genus Brucella allowed the specific amplification of a 1065 bp recA fragment from each of the 38 O. anthropi and the eight Brucella strains investigated. RecA was also amplified from the type strains of O. intermedium, O. tritici, and O. lupini but could not be generated from O. grignonense and O. gallinifaecis. Subsequent comparative recA sequence- and HaeIII-recA restriction fragment length polymorphism analysis identified nine different genospecies among the tested 38 O. anthropi isolates, whereas the recA sequences of the Brucella spp. were indistinguishable. Furthermore, Brucella spp., O. anthropi, O. intermedium, and O. tritici were clearly separated from each other by means of their recA sequences and HaeIII restriction patterns. Five strains of uncertain species status listed in the Culture Collection University of Göteborg bacterial culture collection as O. anthropi were characterized by recA analysis, and their phylogenetic position within the Brucella-Ochrobactrum group was determined. In summary, recA-sequence analysis provides a new reliable molecular subtyping tool to study the phylogeny of the Ochrobactrum taxon at both the inter- and intraspecies level.

Molecular and phenotypic features for identification of the opportunistic pathogens Ochrobactrum spp

Among the six species characterized within the genus Ochrobactrum, Ochrobactrum anthropi and Ochrobactrum intermedium are currently reported as opportunistic pathogens in humans. Since the species identification is mainly based on 16S rDNA analysis, the aim of this study was to search for other characteristics useful for Ochrobactrum species discrimination. Ribotyping, morphological and biochemical analyses, and antimicrobial susceptibility testing were performed for a panel of 35 clinical isolates, first identified to the species level using 16S rDNA sequencing. Type and reference strains of five Ochrobactrum species were comparatively analysed. Commercial identification systems such as API 20NE and VITEK 2 were tested for their ability to identify Ochrobactrum anthropi and to detect other members of the genus Ochrobactrum. An improved protocol for the identification of Ochrobactrum spp. by routine medical microbiology practices is proposed: isolation of a non-fastidious non-fermenting oxidase-positive Gram-negative rod resistant to all beta-lactams except imipenem indicates the genus Ochrobactrum, and the API 20NE system confirms the genus identification for most strains, whereas the VITEK 2 system using ID-GNB cards was less powerful. Urease activity, the mucoidy of the colonies, growth at 45 degrees C on tryptic soy agar, and susceptibility to colistin, tobramycin and netilmicin should be considered as differential characteristics for identification of O. anthropi and O. intermedium to the species level. However, definitive identification depends on genotyping methods.

Ochrobactrum anthropi bacteraemia in immunocompetent children

Ochrobactrum anthropi is an emerging pathogen in immunocompromised patients but infections with the bacterium have very rarely been documented in normal hosts. We report the characteristics of O. anthropi bacteraemia in 11 immunocompetent children, aged 2 months to 7 y, hospitalized in a general hospital during a 5-y period. Children commonly presented with fever, non-specific respiratory or gastrointestinal manifestations, leukocytosis and neutrophilia and had a rapid recovery, even when they did not receive a specific treatment. In 10 cases positive blood cultures were obtained on admission and in all cases subsequent cultures were sterile. In conclusion, O. anthropi may cause bacteraemia in immunocompetent hosts, although further studies are required to clarify whether these isolates represent pseudobacteraemia or whether O. anthropi is a potential pathogen of low virulence.

[Species identification and molecular epidemiology of bacteria belonging to Ochrobactrum genus]

Two species of medical interest belong to the genus Ochrobactrum, Ochrobactrum anthropi and Ochrobactrum intermedium. They are members of the microbiota of soil and an increasing number of works report the isolation of O. anthropi from clinical specimen, especially from immunocompromised patients and nosocomial infection. Involving of each species in human infection is poorly estimated due to unclear differential phenotypic characters. We performed 16S rDNA sequencing for identification of 20 clinical isolates of Ochrobactrum sp. to the species level. Then, we studied the phenotype of each isolate especially, morphology, culture onto different media and at different temperatures, biochemical characters and antibiotics resistance pattern. Colony morphology after growth onto Trypticase-Soy and McConkey agar, culture at 45 degrees C onto Trypticase-Soja agar, presence of urease, and netilmycin, tobramycin and colistin resistance allowed identification of species. Ribotyping using HindIII and EcoRI gave a supplementary criterion for species determination but did not allow typing at the infra-species level. In contrast, Pulsed-Field Gel Electrophoresis showed high degree of polymorphism between strains and proved the clonality of certain isolates. Thus, this method could be a useful tool for molecular epidemiology of Ochrobactrum infections.

Prognostic value of quantitative blood cultures for the outcome of central venous catheters in children

Quantitative blood cultures have been used in order to define catheter-related bloodstream infection (CRBI) in pediatric patients with malignancy and central venous catheters (CVCs). We prospectively followed 32 patients with a total of 38 CVCs for a period of 4 y (14,068 catheter-days). Of a total of 35 cases of bacteremia, 9 were considered to be CRBI (25%). The incidence of bacteremia in our study was 2.48 episodes/1,000 catheter-days and 20/38 CVCs (52%) were affected by bacteremia. The incidence of CRBI was 0.63 episodes/1,000 catheter-days and it was detected in 9/38 CVCs (23%). The catheter salvage rate in cases of bacteremia, irrespective of etiology, was 30/35 (85%). The catheter salvage rate in cases of CRBI was only 4/9 (44%), whereas all the catheters (26/26) in non-catheter-related cases of bacteremia were salvaged. We suggest that the use of quantitative blood cultures is a useful tool for the evaluation of bacteremia in patients with CVCs and is of prognostic value.

Ochrobactrum anthropi bloodstream infection complicating hemodialysis

We report two cases of bacteremia with Ochrobactrum anthropi in patients on hemodialysis. Bacteremia became clinically manifest by recurrent febrile episodes during and after dialysis. In one patient, bacteremia persisted after ciprofloxacin therapy and was cleared only by removal of the dialysis catheter and a 3-week course of gentamicin. The second patient remained intermittently bacteremic for more than 3 months, although the dialysis catheter had been replaced. A MEDLINE search revealed only one previous report of O anthropi bloodstream infection in a patient on hemodialysis, but the pathogen is recognized increasingly as a causative agent of human disease, most importantly in debilitated patients. In contrast to most previously described cases, the two patients reported here had no malignancies and were not on immunosuppressive therapy. Treatment of O anthropi infection is challenging because of widespread and unpredictable resistance to antimicrobial agents and discrepancies between in vitro susceptibility and in vivo efficacy.