Clinical Significance of Isolates Known to Be Blood Culture Contaminants in Pediatric Patients

Background and objectives: The objective of this study was to investigate the clinical significance of isolates from blood stream infection known to be blood culture contaminants in pediatric patients. Materials and Methods: Microbiological reports and medical records of all blood culture tests issued from 2002 to 2012 (n = 76,331) were retrospectively reviewed. Evaluation for potential contaminants were done by reviewing medical records of patients with the following isolates: coagulase-negative Staphylococcus, viridans group Streptococcus, Bacillus, Corynebacterium, Micrococcus, Aerococcus, and Proprionibacterium species. Repeated cultures with same isolates were considered as a single case. Cases were evaluated for their status as a pathogen. Results: Coagulase-negative Staphylococcus had clinical significance in 23.8% of all cases. Its rate of being a true pathogen was particularly high in patients with malignancy (43.7%). Viridans group Streptococcus showed clinical significance in 46.2% of all cases. Its rate of being a true pathogen was similar regardless of the underlying morbidity of the patient. The rate of being a true pathogens for remaining isolates was 27.7% for Bacillus and 19.0% for Corynebacterium species. Conclusions: Coagulase-negative Staphylococcus and viridans group Streptococcus isolates showed high probability of being true pathogens in the pediatric population, especially in patients with underlying malignancy.

A Dorsal homolog (FcDorsal) in the Chinese shrimp Fenneropenaeus chinensis is responsive to both bacteria and WSSV challenge

Rel/NFkappaB is a family of transcription factors. In the present study, a Rel/NFkappaB family member, Dorsal homolog (FcDorsal) was cloned from the Chinese shrimp Fenneropenaeus chinensis. The full length cDNA of FcDorsal consists of 1627bp, revealed a 1071bp open reading frame encoding 357 aa. The predicted molecular weight (MW) of the deduced amino acid sequence of FcDorsal was 39.78kDa, and its theoretical pI was 8.85. Amino acid sequence analysis showed that FcDorsal contains a Rel homolog domain (RHD) and an IPT/TIG (Ig-like, plexins and transcriptions factors) domain. The signature sequence of dorsal protein existed in the deduced amino acid sequence. Spatial expression profiles showed that FcDorsal had the highest expression level in the hemocytes and lymphoid organ (Oka). The expression profiles in the hemocytes and lymphoid organ were apparently modulated when shrimp were stimulated by bacteria or WSSV. Both Gram-positive (G(+)) bacteria (Micrococcus lysodeikticus) and Gram-negative (G(-)) bacteria (Vibrio anguillarium) injection to shrimp caused the up-regulation of FcDorsal at the transcription level. DsRNA approach was used to study the function of FcDorsal and the data showed that FcDorsal was related to the transcription of Penaeidin 5 in shrimp. The present data provide clues that FcDorsal might play potential important roles in the innate immunity of shrimp. Through comparison of the expression profiles between FcDorsal and another identified Rel/NFkappaB member (FcRelish) in shrimp responsive to WSSV challenge, we speculate that FcDorsal and FcRelish might play different roles in shrimp immunity.

Micrococcus sedentarius bacteraemia presenting with haemophagocytic syndrome in previously healthy boy

Haemophagocytic syndromes are the clinical manifestation of an increased macrophagic activity with haemophagocytosis. Infection-associated HS was originally described by Risdall in 1979, in viral disease. Since the initial description HS has also been documented in patients with bacterial, parasitic or fungal infections. We describe a case of Micrococcus sedentarius bacteraemia in a previously healthy 10-y-old boy with haemophagocytic syndrome. Species of micrococci are generally considered as non-pathogenic commensals that colonize the skin, mucosae and oropharynx. We report the first case of Microccoccus sedentarius bacteraemia in an immunocompetent host and first case of HS associated with Micrococcus species.

A marine bacterium, Micrococcus MCCB 104, antagonistic to vibrios in prawn larval rearing systems

A marine bacterium, Micrococcus MCCB 104, isolated from hatchery water, demonstrated extracellular antagonistic properties against Vibrio alginolyticus, V. parahaemolyticus, V. vulnificus, V. fluviallis, V. nereis, V. proteolyticus, V. mediterranei, V cholerae and Aeromonas sp., bacteria associated with Macrobrachium rosenbergii larval rearing systems. The isolate inhibited the growth of V. alginolyticus during co-culture. The antagonistic component of the extracellular product was heat-stable and insensitive to proteases, lipase, catalase and alpha-amylase. Micrococcus MCCB 104 was demonstrated to be non-pathogenic to M. rosenbergii larvae.

Micrococcus-associated central venous catheter infection in patients with pulmonary arterial hypertension

STUDY OBJECTIVES

To determine the incidence of catheter-related infection in patients with pulmonary arterial hypertension (PAH) receiving epoprostenol (EPO), and to note an etiologic role for Micrococcus spp, which is rarely reported as a pathogen in the medical literature.

DESIGN

Observational study.

SETTING

Two PAH specialty treatment centers, Harbor-UCLA Medical Center (Torrance, CA), and the College of Physicians and Surgeons, Columbia University (New York, NY).

PATIENTS

A total of 192 patients with PAH receiving continuous therapy with IV EPO.

INTERVENTIONS

From 1987 to 2000, 192 patients with PAH received infusions of EPO via central venous catheter. Catheter care included regular dressing changes with dry gauze using a sterile procedure, without the use of flushes. Patients were asked to report on known infections and treatments, and symptoms. All infections were verified by a telephone call to the patient, care provider, and microbiology laboratory whenever possible.

MEASUREMENTS AND RESULTS

There were 335,285 catheter days (mean +/- SD, 1,325 +/- 974 catheter days). There were 88 clinical catheter infections with 51 blood culture-positive infections, necessitating catheter removal in 38 instances. The following pathogens were isolated: Staphylococcus aureus (25); Micrococcus spp (14); mixed flora (3); coagulase-negative Staphylococcus spp (2); Corynebacterium spp (2); Serratia marcessens (1); Enterobacter spp (1); Pseudomonas aeruginosa (1); enterococci (1); and unidentified Gram-positive cocci (1). The catheter infection rate was 0.26 per 1,000 catheter days.

CONCLUSIONS

The use of long-term therapy with continuous EPO appears to be associated with a low incidence of catheter-related infections. Micrococcus spp were the second most common etiologic agent. Caregivers managing patients with PAH must be aware of the risk of catheter infection, as it may contribute to the morbidity and mortality associated with the use of EPO. When isolated, Micrococcus spp should not be viewed as a contaminant, but rather as a true pathogen that may require therapeutic intervention.

Acute infection of mice with Smith strain of Staphylococcus aureus

Two serologically distinct variants found in a unique strain of staphylococcus produce coagulase and are phagocytized, but only one is virulent to mice. Only virulent cocci grow rapidly within leukocytes. Leukocyte destruction by the virulent strain and release of many phagocytized cocci precedes mouse death. The leukocidic agent may be delta-hemolysin.

A quantitative study of the kinetics of blood clearance of P32-labelled Escherichia coli and Staphylococci by the reticuloendothelial system

1. The clearance of P³²-labelled heat-killed E. coli and staphylococci from the blood follows an exponential function of the time, and the bacteria are phagocytized principally by the RES of the liver and spleen. 2. The rates of clearance of equivalent number of E. coli from the blood is rapid in rabbits and slow in mice and appears to be related to the level of antibodies in the serum of these animals. 3. Unlike E. coli, staphylococci are cleared rapidly and efficiently by the RES from the blood of mice which have a sufficient level of serum antibody against these bacteria. 4. The numbers of bacteria, phagocytized by the liver or the spleen respectively, depend upon the rate of clearance and the extent of opsonization of the bacteria. Rapidly cleared, well opsonized E. coli are removed almost exclusively by the liver, while less efficiently phagocytized bacteria are also cleared by the spleen in large numbers. 5. The rate of clearance of E. coli and the efficiency with which they are phagocyted by the RES in mice have been shown to be directly related to the level of antibody in the serum. 6. Treatment of mice with S. typhi or Serratia marcescens endotoxins increases the rate of clearance of E. coli from the blood and the level of antibody against E. coli in the serum. The enhanced clearance of E. coli can be transferred to normal mice by the serum of endotoxin-treated mice.

Grading of coagulase-positive staphylococci in the control of hospital cross-infection

The fermentation of mannitol by coagulase-positive staphylococci has been studied. It was found difficult to obtain reproducible results by methods which could be conveniently used in a routine department.

A method of grading based on the fermentation of mannitol has been examined. Organisms of the supposedly most dangerous grade (Grade A) were isolated slightly more frequently from lesions than from carriers, but from all sources a high proportion of strains belonged to this grade.

It was not possible to correlate the grades to which staphylococci were assigned with their production of diffusible antigens.

In this hospital it seems that the proportion of strains assigned to Grade A has become very much higher than it was 15 years ago.

We thank Prof. R. Knox, Mr J. B. Blaikley, Dr W. H. H. Merivale, and Dr R. H. Gorrill for the help and advice they have given us in the course of this investigation and numerous members of the nursing staff of Guy's Hospital for their co-operation in checking records and answering questions.

Micrococcus folliculitis in HIV-1 disease

Organisms with little pathogenic potential in immunocompetent hosts may produce disease in HIV-1 + patients. We describe three HIV-1 + patients in late disease who presented with pruritic papules with central ulceration over the face and arms. In all the patients the eruptions had been present for months, and the patients did not develop sepsis. Biopsy specimens in all the patients showed large Gram-positive cocci, forming tetrads. Colony morphology, catalase positivity and coagulase negativity, and resistance to nitrofurantoin were used to separate micrococci from staphylococci. Micrococcus species are usually considered normal inhabitants of the skin; however, in patients with HIV-1 disease, Micrococcus species can produce localized cutaneous infections.

Gram-positive, catalase-positive cocci from dry cured Iberian ham and their enterotoxigenic potential

Iberian ham is an uncooked, cured meat product ripened under natural uncontrolled conditions for 18 to 24 months. Gram-positive, catalase-positive cocci are the main microbial population in Iberian ham for most of the ripening time. Since some of these organisms are able to produce enterotoxins, adequate characterization and toxicological study are needed. For this, 1,327 gram-positive, catalase-positive cocci, isolated from Iberian hams at different stages and locations, were characterized by physiological and biochemical tests. Selected isolates were further characterized by guanine-cytosine (G+C) content and restriction enzyme analysis of genes coding for 16S rRNA. The toxigenic potential of these organisms was tested with specific DNA gene probes for staphylococcal enterotoxins A, B, C, and D and confirmed by semiquantitative sandwich enzyme immunoassay. The majority of the isolates were identified as Staphylococcus spp. and Micrococcus spp. Non-identified gram-positive, catalase-positive cocci which were moderately halophilic and showed a 42 to 52% G+C content were detected. A great variety of staphylococcal strains were found within the different species at any sampling time. Two strains of Staphylococcus xylosus, one Staphylococcus cohnii strain, and four of the non-identified organisms with 42 to 52% G+C contents hybridized with some of the DNA probes for C and D staphylococcal enterotoxin genes. S. xylosus hybridizing with C-enterotoxin probe reacted with both C and D enterotoxins in the immunological test. In addition, enterotoxin D was confirmed in the nonidentified strains. Some toxigenic organisms were isolated from the final product, posing a health hazard for the consumer.

[The probable utilization of the protective properties of the vector's saliva by the causative agents of specifically tick-borne infections]

It is proved that in the tick fluid saliva and in the cement plug produced by Rhipicephalus appendiculatus there are bactericidal substances very similar in their activity to the egg lysozyme. The possible role in the transmission and conservation of the specific tick-borne, insensitive to the lysozyme pathogens such as rickettsiae, tick-borne encephalitides virus and borreliae (pathogen of Lyme disease) is discussed. It is supposed, that bactericidal substances in the cement plug protect accumulated in it the tick-borne pathogens (TBE virus, borreliae) from the compete and destructive influence of the vulgar, mainly coccal microflora and from the purulent inflammation, which hinders not only tick feeding but probably specific tick-borne pathogens spreading in the vertebrate host.

[Changes in the chromatin structure under the influence of intranuclear bacteria with antihistone activity]

Computed TV morphodensitometry was used to examine the integration of bacteria into the human nuclear genome. The bacterial strains with antihistone activity were shown to be incorporated into the structure of chromatin structure of an epithelial cell with its network organization impaired. The microscopic analysis of cultured Hep 2 cells by manual scanning indicated that genetically active bacteria were incorporated into the nucleus and nucleolus.

Intracranial suppuration caused by Micrococcus luteus

Micrococcus spp. are commensal organisms colonizing the body surfaces of humans. In a few instances these organisms have been reported to colonize ventricular shunts. We report a patient, with no overt evidence of immunosuppression, in whom Micrococcus luteus was responsible for intracranial suppuration at multiple sites.