What causes symptoms suggestive of tuberculosis in HIV-positive people with negative initial investigations?

OBJECTIVE:

To identify the causes of symptoms suggestive of tuberculosis (TB) among people living with the human immunodeficiency virus (PLHIV) in South Africa.

METHODS:

A consecutive sample of HIV clinic attendees with symptoms suggestive of TB (⩾1 of cough, weight loss, fever or night sweats) at enrolment and at 3 months, and negative initial TB investigations, were systematically evaluated with standard protocols and diagnoses assigned using standard criteria. TB was ‘confirmed’ if Mycobacterium tuberculosis was identified within 6 months of enrolment, and ‘clinical’ if treatment started without microbiological confirmation.

RESULTS:

Among 103 participants, 50/103 were preantiretroviral therapy (ART) and 53/103 were on ART; respectively 68% vs. 79% were female; the median age was 35 vs. 45 years; the median CD4 count was 311 vs. 508 cells/mm³. Seventy-two (70%) had ⩾5% measured weight loss and 50 (49%) had cough. The most common final diagnoses were weight loss due to severe food insecurity (n = 20, 19%), TB (n = 14, 14%: confirmed n = 7; clinical n = 7), other respiratory tract infection (n = 14, 14%) and post-TB lung disease (n = 9, 9%). The basis for TB diagnosis was imaging (n = 7), bacteriological confirmation from sputum (n = 4), histology, lumbar puncture and other (n = 1 each).

CONCLUSION:

PLHIV with persistent TB symptoms require further evaluation for TB using all available modalities, and for food insecurity in those with weight loss.

Temporal association of infant immunisation with pneumococcal conjugate vaccine on the ecology of Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus nasopharyngeal colonisation in a rural South African community

BACKGROUND

Immunisation of children with pneumococcal conjugate vaccines (PCV) may affect the bacterial-ecology of the nasopharynx, including colonisation by Streptococcus pneumoniae, Haemophilus influenzae and Staphylococcus aureus. The aim of this study was to evaluate the effect of infant PCV-immunisation on the nasopharyngeal ecology of these potentially pathogenic bacteria in a rural African setting.

METHODS

Two cross sectional surveys were undertaken from May to October in 2009 (Period-1) which coincided with the introduction of 7-valent PCV (PCV7) and in May-October 2011 (Period-2). Consenting household members, where there was a child <2 years of age in residence, had nasopharyngeal swabs undertaken for culture.

RESULTS

From Period-1 to Period-2 in children 0-2 years and 3-12 years, prevalence of overall S. pneumoniae colonisation decreased from 74.9% to 67.0% (p<0.001) and H. influenzae declined among children 3-12 years (55.1-45.3%, p<0.001) but not among those <2 years. The prevalence of S. aureus remained unchanged in all children. Competitive associations were found between S. pneumoniae and S. aureus and between H. influenzae and S. aureus among children. In individuals >12 years, the prevalence of colonisation decreased from 11.2% to 6.8%, 16.7% to 8.8% and 31.2% to 23.7% for S. pneumoniae, H. influenzae and S. aureus, respectively; p<0.001 for all comparions. Synergistic relationships for S. aureus with H. influenzae and S. pneumoniae were observed in both periods among this group.

Comparison of the effects of macrolides, amoxicillin, ceftriaxone, doxycycline, tobramycin and fluoroquinolones, on the production of pneumolysin by Streptococcus pneumoniae in vitro

OBJECTIVES

To compare the effects of subinhibitory concentrations of amoxicillin, ceftriaxone, azithromycin, clarithromycin, erythromycin, telithromycin, clindamycin, ciprofloxacin, moxifloxacin, tobramycin and doxycycline on pneumolysin production by a macrolide-susceptible strain and two macrolide-resistant strains [erm(B) or mef(A)] of Streptococcus pneumoniae.

METHODS

Pneumolysin was assayed using a functional procedure based on the influx of Ca(2+) into human neutrophils.

RESULTS

Only the macrolides/macrolide-like agents caused significant attenuation of the production of pneumolysin, which was evident with all three strains of the pneumococcus.

CONCLUSIONS

Macrolides, at sub-MICs, but not other classes of antibiotic, subvert the production of pneumolysin, even in the presence of (and irrespective of the mechanism of) macrolide resistance in S. pneumoniae.

Clarithromycin alone and in combination with ceftriaxone inhibits the production of pneumolysin by both macrolide-susceptible and macrolide-resistant strains of Streptococcus pneumoniae

OBJECTIVES

To investigate the effects of clarithromycin (0.01-0.5 mg/L) alone or in combination with ceftriaxone (0.1 and 0.25 mg/L) on pneumolysin production by both macrolide-susceptible and -resistant [2 erm(B) positive and 2 mef(A) positive] strains of Streptococcus pneumoniae.

METHODS

The bacteria were cultured for 6 h at 37 degrees C/5% CO(2) in tryptone soy broth, washed, enumerated and resuspended to 0.5-3 x 10(8) cfu/mL in tissue culture medium, RPMI 1640. After 16 h of incubation at 37 degrees C / 5% CO(2), pneumolysin was assayed in the bacteria-free supernatants, as well as in lysates, using a functional assay based on the influx of calcium into human neutrophils.

RESULTS

Exposure of not only macrolide-susceptible strains, but also the macrolide-resistant strains, of S. pneumoniae to sub-MICs of clarithromycin resulted in dose-related inhibition of the pneumolysin production, whereas production of the toxin was unaffected by ceftriaxone.

CONCLUSIONS

These observations demonstrate that even in the setting of macrolide resistance the production of pneumolysin, a key virulence factor of the pneumococcus, is attenuated by exposure of this microbial pathogen to clarithromycin.

Impact of conjugate Haemophilus influenzae type b (Hib) vaccine introduction in South Africa

OBJECTIVE

To analyse trends in reported invasive Haemophilus influenzae disease in South Africa within the first five years of introduction of conjugate Haemophilus influenzae type b (Hib) vaccine in the routine child immunization schedule.

METHODS

We used national laboratory-based surveillance data to identify cases of invasive H. influenzae disease between July 1999 and June 2004, and submitted isolates for serotyping and antimicrobial susceptibility testing.

FINDINGS

The absolute number of Hib cases (reported to the national surveillance system) among children below one year of age decreased by 65%, from 55 cases in 1999-2000 to 19 cases in 2003-04. Enhanced surveillance initiated in 2003, identified human immunodeficiency virus (HIV)-infection and incomplete vaccination as contributing factors for Hib transmission. The total number of laboratory-confirmed cases of H. influenzae remained unchanged because non-type b disease was being increasingly reported to the surveillance system concomitant with system enhancements. Children with non-typable disease were more likely to be HIV-positive (32 of 34, 94%) than children with Hib disease (10 of 14, 71%), P = 0.051. Recent Hib isolates were more likely to be multidrug resistant (2% in 1999-2000 versus 19% in 2003-04, P = 0.001).

CONCLUSION

Data from a newly established national laboratory-based surveillance system showed a decrease in Hib disease burden among South African children following conjugate vaccine introduction and identified cases of non-typable disease associated with HIV infection.

Nosocomial outbreak of extended-spectrum beta-lactamase-producing Salmonella isangi in pediatric wards

Since May 2000, extended-spectrum beta-lactamase-producing (ESBL) Salmonella Isangi were isolated from pediatric patients at a tertiary hospital. A total of 41 patients with positive cultures were reviewed, and the majority presented with gastroenteritis, fever, or both. One ESBL phenotype was noted in all isolates, and clonality was confirmed by pulsed-field gel electrophoresis. This is the first report of Salmonella sp. ESBL resistance in our hospital.

Utility of blood cultures and incidence of mycobacteremia in patients with suspected tuberculosis in a South African infectious disease referral hospital

SETTING

A 500-bed government referral institution for patients with tuberculosis and other infectious diseases in Gauteng, South Africa.

OBJECTIVES

To assess the usefulness of BACTEC blood cultures over and above that of other microbiological methods for the diagnosis of tuberculosis in patients who are suspected of suffering from tuberculosis.

DESIGN

Mycobacterial blood cultures were obtained from patients presenting with symptoms suspicious of tuberculosis and where there was no clinical evidence of other infectious etiologies, and from patients who had failed tuberculosis treatment.

RESULTS

Sixteen (22%) of 71 patients included in the study were positive for Mycobacterium tuberculosis on blood culture, while seven (10%) were positive for M. avium complex (MAC). Twelve (75%) of the patients with tuberculosis and positive blood cultures were however also positive for acid-fast bacilli on sputum smears and eight (50%) were initially diagnosed clinically and radiographically as localized pulmonary tuberculosis. Blood cultures positive for mycobacteria were only found among patients with human immunodeficiency virus infection (HIV).

CONCLUSIONS

Bacteremia with M. tuberculosis complex was detected in HIV-infected patients with suspected tuberculosis, even in patients presenting with localized pulmonary infection on initial clinical assessment. Among patients with suspected tuberculosis, blood cultures were useful in diagnosing unsuspected MAC disease, but did not add to the diagnostic yield of conventional tests for tuberculosis used routinely, namely sputum microscopy and culture, or occasional biopsy specimens.

Epidemiology of glycopeptide-resistant enterococci colonizing high-risk patients in hospitals in Johannesburg, Republic of South Africa

Recent cases of infections caused by glycopeptide-resistant enterococci (GRE) have highlighted the emergence of these organisms in the Republic of South Africa. During May 1998 we conducted a prevalence study in four hospitals in Johannesburg and obtained 184 rectal swabs from patients identified as being at high risk for GRE colonization. Twenty enterococcal isolates showing various glycopeptide resistance genotypes were recovered: 3 Enterococcus faecium vanA isolates, 10 E. faecium vanB isolates, 6 E. gallinarum vanC1 isolates, and 1 E. avium vanA isolate. Macrorestriction analysis was used to demonstrate the clonal spread of GRE strains within hospitals. Evidence also demonstrated the likely persistence of the original E. faecium vanA isolate associated with the first confirmed death contributed to by GRE infection in South Africa in March 1997.