Candidal infections of ventriculoperitoneal shunts.

Although ventriculoperitoneal (VP) shunt infection is a common complication of shunt procedures, fungal infection is considered to be rare. In the present study, we performed retrospective analysis of six cases in which candida infection occurred. In all these six cases, VP shunt was performed in children for hydrocephalus and the onset of symptoms varied between seven days to one month after the surgical procedure was performed. The commonest clinical signs and symptoms were fever (100%), vomiting (100%), and altered sensorium (50%). The commonest isolate was Candida albicans (66.66%) followed by Candida parapsilosis and Candida glabrata in one case each. All the patients were successfully treated with Amphotericin B and there was no mortality recorded.

Introduction

Ventriculoperitoneal (VP) shunt is one of the commonest procedures in neurosurgical practice. Infection is still the most common complication of shunt procedures in children.[1] However, fungal infection is still considered to be rare. Only few cases have been reported.[1-4] The clinical manifestations are subtle and insidious. The commonest fungal infection reported, of the central nervous system (CNS), is candidal meningitis.[1-5] We undertook a retrospective analysis of six cases from which the Candida species were isolated from ventriculoperitoneal shunt fluids.

Materials and Methods

A retrospective analysis of six cases of candidal infection of the VP shunt was carried out in children ranging from newborns to six months. The data collected included age, sex, underlying predisposing factors, and clinical manifestations. The VP shunt fluid was processed with the help of a microscopic examination and the cultures were performed on Blood agar, MacConkey's agar, and Sabouraud's Dextrose agar (SDA). When a colony appeared on SDA, the yeast was identified using the Germ tube test, the growth pattern on Cornmeal agar (CMA) and Tobacco agar, and sugar assimilation tests.

Results

Out of the 24 suspected cases of VP shunt infections, the Candida species were isolated in six (25%) cases. All the patients were in the age group of neonate to six months. Shunt infection was defined as an isolation of the organism from the ventricular fluid, shunt tube, and reservoir, along with signs or symptoms suggestive of shunt infection or malfunction. All the patients had undergone the shunt procedure under an antibiotic cover, with a combination of augmentin, gentamicin, ceftriaxone or ciprofloxacin. All the six cases were premature babies with birth weight ranging from 1000 to 2000 grams, their median gestational age being 26 weeks. All these patients had VP shunts as treatment for hydrocephalus. The time of onset of clinical presentation ranged between seven days to one month after placement of the shunt. The clinical manifestation was fever (100%), vomiting (100%), and altered sensorium in 50% of the cases. Cerebrospinal fluid (CSF) analysis showed neutrophilic pleocytosis. Gram staining of the fluid showed a presence of yeast cells in only three (50%) cases. Out of the six isolated Candida species, the commonest was Candida albicans 66.6% (4/6) followed by Candida parapsilosis and Candida glabrata in one case each. In all the six cases no bacteria were isolated from the fluid. Patients were given intravenous Amphotericin B and all the patients responded and no mortality was noted in the study.

Discussion

Meningitis caused by Candida species is a serious condition that may result in significant morbidity and mortality if not recognized and treated effectively.[6] Although candida meningitis remains rare, its frequency has increased in the last few years, particularly in patients undergoing neurosurgical procedures such as VP shunts.[1-6] Infection is a common complication of ventriculoperitoneal shunt (VP) placement. Infection of VP shunts varies between 2 to 27%.[78] CNS shunt infection is a cause of significant morbidity, causing malfunction and chronic ill health, and a few cases may even turn fatal. Shunt associated infections are most frequently caused by Coagulase Negative Staphylococcus (CONS) (65%) followed by Gram negative bacteria.[7] Candida is the causative agent in 1% of these infections.[9] However, this reported incidence of VP shunt infection might be underestimated, considering that some of the cultures, negative for bacterial culture, might have a fungal etiology. Higher percentage of candidal infection of the VP shunt is reported in our study.

Chiou et al,[1] found that fungi accounted for 17% of shunt infections (8/48) in a retrospective study performed in 1994. Our findings, that is, 25% of shunt infections were due to fungi, is comparable with that study. Even higher infection rates with Candida species, that is, 59% was reported by Viudes et al.[6] and 74% by Fernandez et al.[5]

In our study, all the six patients from whom Candida species were isolated were premature babies with birth weight ranging from 1000 to 2000 grams and the median gestational age was 26 weeks.

Viudes,[6] while studying 15 patients with ages ranging from one year to 65 years, showed that the most common neurosurgical procedure performed was for the treatment of hydrocephalus.

Chiou et al.[1] reported that all the infections due to Candida species occurred in premature babies, as noted in the present study, and the underlying factors were the neurosurgical procedures performed for the treatment of hydrocephalus. Viudes et al.[6] also showed that hydrocephalus was the only underlying procedure performed before the development of shunt infection. Prematurity as an underlying cause was also noted earlier by Lee et al.,[4] one month after the neurosurgical procedure for hydrocephalus was performed.

In one review,[10] 77% of candida infections developed within three months of shunt manipulation, suggesting inoculation of the organism during surgery as suggested by Nguyaen et al.[2] Other risk factors for candida shunt infections and meningitis include administration of broad spectrum antibiotics, prior or concurrent meningitis, cerebrospinal fluid leakage, bowel perforation, and/or abdominal surgery, steroids, and indwelling catheters.[9] In this study, all the patients presented with clinical symptoms from seven days to one month after neurosurgical procedure for hydrocephalus was performed. Transient candidemia and secondary colonization of VP shunts have been suggested by other investigators as a possible source of infecting candida organisms.[11] This might have happened in the cases reported here.

The clinical presentation of a candida shunt infection depends upon the location of infection. Distal shunt infection refers to an infection at the site of the shunt drainage, which is either a vascular site such as the right atrium, the symptoms are nonspecific and include fever and malaise. An infected shunt draining into the peritoneum causes mesothelial inflammation and subsequently decreases drainage. A “shuntoma” can develop when the peritoneum encysts the fluid. Proximal candida shunt infections are manifested by malfunction associated with high intracranial pressure, including headaches, nausea, vomiting, and altered mental status. The most common symptoms of ventriculoperitoneal infections include fever (31%) and meningoencephalitis (21%).[9-11]

Out of the six isolates of the Candida species in the present study, Candida albicans was the most common 66.66% (4/6) cases, while Candida parapsilosis and Candida glabrata were isolated in one case each. Candida albicans has been reported as the predominant isolate in all reports earlier,[1-6] followed by Candida parapsilosis. Other species of candida reported are Candida tropicalis and Candida famata.[

The predominant clinical manifestations in all the individuals in the present study were fever (100%), vomiting (100%), and altered sensorium in 50% of the cases. Sanchez-Patocarreo et al.,[3] in his study, showed that fever was present in 31% of the patients, signs of meningoencephalitis in 21% of the patients, while abdominal symptoms were present in 10% of the cases. In the present study the abdominal symptom present was vomiting in 100% of the cases.

Cerebrospinal fluid analysis showed pleocytosis in all cases that was indistinguishable from bacterial infection. Similar findings were also reported by Nguyaen et al.,[2] but lymphocytic predominance was reported by Sanchez-Patocarreo et al.[3]

All the patients who received Amphotericin B in the present study survived. Amphotericin B is effective against all species of Candida including Candida glabrata, which is inherently resistant to Fluconazole. Hence, identification of the species is important, as this gives a clue to the treating clinician for choosing the proper antifungal agent.

Nguyen et al.[2] reported 11% mortality, while Sanchez-Patocarreo et al.[3] reported mortality in 9% of the cases. A higher mortality of 27% was reported by Viudes et al.[6] No mortality was reported in the present study.

To conclude, this study highlights the importance of early diagnosis and proper treatment of VP shunt fungal infections,,to prevent mortality.